diff options
| author | Kirill Volinsky <mataes2007@gmail.com> | 2017-11-25 18:26:37 +0300 |
|---|---|---|
| committer | Kirill Volinsky <mataes2007@gmail.com> | 2017-11-25 18:26:37 +0300 |
| commit | 7c7b6e4e4ccb67ea885fce90af3b0167894a30db (patch) | |
| tree | 1d8620742b63be5afe1285b71bb5942abe71aeab /plugins/AdvaImg/src | |
| parent | 867c7e500c975c579796a3047962738774270ee0 (diff) | |
update libpng to 1.6.34
Diffstat (limited to 'plugins/AdvaImg/src')
27 files changed, 524 insertions, 7596 deletions
diff --git a/plugins/AdvaImg/src/LibPNG/ANNOUNCE b/plugins/AdvaImg/src/LibPNG/ANNOUNCE index db2329684f..c25ca741dc 100644 --- a/plugins/AdvaImg/src/LibPNG/ANNOUNCE +++ b/plugins/AdvaImg/src/LibPNG/ANNOUNCE @@ -1,4 +1,4 @@ -Libpng 1.6.31 - July 27, 2017
+Libpng 1.6.34 - September 29, 2017
This is a public release of libpng, intended for use in production codes.
@@ -7,51 +7,24 @@ Files available for download: Source files with LF line endings (for Unix/Linux) and with a
"configure" script
- libpng-1.6.31.tar.xz (LZMA-compressed, recommended)
- libpng-1.6.31.tar.gz
+ libpng-1.6.34.tar.xz (LZMA-compressed, recommended)
+ libpng-1.6.34.tar.gz
Source files with CRLF line endings (for Windows), without the
"configure" script
- lpng1631.7z (LZMA-compressed, recommended)
- lpng1631.zip
+ lpng1634.7z (LZMA-compressed, recommended)
+ lpng1634.zip
Other information:
- libpng-1.6.31-README.txt
- libpng-1.6.31-LICENSE.txt
- libpng-1.6.31-*.asc (armored detached GPG signatures)
-
-Changes since the last public release (1.6.30):
-
- Guard the definition of _POSIX_SOURCE in pngpriv.h (AIX already defines it;
- bug report by Michael Felt).
- Revised pngpriv.h to work around failure to compile arm/filter_neon.S
- ("typedef" directive is unrecognized by the assembler). The problem
- was introduced in libpng-1.6.30beta01.
- Added "Requires: zlib" to libpng.pc.in (Pieter Neerincx).
- Added special case for FreeBSD in arm/filter_neon.S (Maya Rashish).
- Added instructions for disabling hardware optimizations in INSTALL.
- Added "--enable-hardware-optimizations" configuration flag to enable
- or disable all hardware optimizations with one flag.
- Updated CMakeLists.txt to add INTEL_SSE and MIPS_MSA platforms.
- Changed "int" to "png_size_t" in intel/filter_sse2.c to prevent
- possible integer overflow (Bug report by John Bowler).
- Quieted "declaration after statement" warnings in intel/filter_sse2.c.
- Added scripts/makefile-linux-opt, which has hardware optimizations enabled.
- Removed one of the GCC-7.1.0 'strict-overflow' warnings that result when
- integers appear on both sides of a compare. Worked around the others by
- forcing the strict-overflow setting in the relevant functions to a level
- where they are not reported (John Bowler).
- Changed "FALL THROUGH" comments to "FALLTHROUGH" because GCC doesn't like
- the space.
- Worked around some C-style casts from (void*) because g++ 5.4.0 objects
- to them.
- Increased the buffer size for 'sprint' to pass the gcc 7.1.0 'sprint
- overflow' check that is on by default with -Wall -Wextra.
- Added eXIf chunk support.
- Added a minimal eXIf chunk (with Orientation and FocalLengthIn35mmFilm
- tags) to pngtest.png.
+ libpng-1.6.34-README.txt
+ libpng-1.6.34-LICENSE.txt
+ libpng-1.6.34-*.asc (armored detached GPG signatures)
+
+Changes since the last public release (1.6.33):
+ Removed contrib/pngsuite/i*.png; some of these were incorrect and caused
+ test failures.
Send comments/corrections/commendations to png-mng-implement at lists.sf.net
(subscription required; visit
diff --git a/plugins/AdvaImg/src/LibPNG/CHANGES b/plugins/AdvaImg/src/LibPNG/CHANGES index 6447bbb3c6..80f4c771b5 100644 --- a/plugins/AdvaImg/src/LibPNG/CHANGES +++ b/plugins/AdvaImg/src/LibPNG/CHANGES @@ -833,7 +833,7 @@ Version 1.0.7beta11 [May 7, 2000] Removed the new PNG_CREATED_READ_STRUCT and PNG_CREATED_WRITE_STRUCT modes
which are no longer used.
Eliminated the three new members of png_text when PNG_LEGACY_SUPPORTED is
- defined or when neither PNG_READ_iTXt_SUPPORTED nor PNG_WRITE_iTXT_SUPPORTED
+ defined or when neither PNG_READ_iTXt_SUPPORTED nor PNG_WRITE_iTXt_SUPPORTED
is defined.
Made PNG_NO_READ|WRITE_iTXt the default setting, to avoid memory
overrun when old applications fill the info_ptr->text structure directly.
@@ -5908,6 +5908,139 @@ Version 1.6.31rc02 [July 25, 2017] Version 1.6.31 [July 27, 2017]
No changes.
+Version 1.6.32beta01 [July 31, 2017]
+ Avoid possible NULL dereference in png_handle_eXIf when benign_errors
+ are allowed. Avoid leaking the input buffer "eXIf_buf".
+ Eliminated png_ptr->num_exif member from pngstruct.h and added num_exif
+ to arguments for png_get_eXIf() and png_set_eXIf().
+ Added calls to png_handle_eXIf(() in pngread.c and png_write_eXIf() in
+ pngwrite.c, and made various other fixes to png_write_eXIf().
+ Changed name of png_get_eXIF and png_set_eXIf() to png_get_eXIf_1() and
+ png_set_eXIf_1(), respectively, to avoid breaking API compatibility
+ with libpng-1.6.31.
+
+Version 1.6.32beta02 [August 1, 2017]
+ Updated contrib/libtests/pngunknown.c with eXIf chunk.
+
+Version 1.6.32beta03 [August 2, 2017]
+ Initialized btoa[] in pngstest.c
+ Stop memory leak when returning from png_handle_eXIf() with an error
+ (Bug report from the OSS-fuzz project).
+
+Version 1.6.32beta04 [August 2, 2017]
+ Replaced local eXIf_buf with info_ptr-eXIf_buf in png_handle_eXIf().
+ Update libpng.3 and libpng-manual.txt about eXIf functions.
+
+Version 1.6.32beta05 [August 2, 2017]
+ Restored png_get_eXIf() and png_set_eXIf() to maintain API compatability.
+
+Version 1.6.32beta06 [August 2, 2017]
+ Removed png_get_eXIf_1() and png_set_eXIf_1().
+
+Version 1.6.32beta07 [August 3, 2017]
+ Check length of all chunks except IDAT against user limit to fix an
+ OSS-fuzz issue (Fixes CVE-2017-12652).
+
+Version 1.6.32beta08 [August 3, 2017]
+ Check length of IDAT against maximum possible IDAT size, accounting
+ for height, rowbytes, interlacing and zlib/deflate overhead.
+ Restored png_get_eXIf_1() and png_set_eXIf_1(), because strlen(eXIf_buf)
+ does not work (the eXIf chunk data can contain zeroes).
+
+Version 1.6.32beta09 [August 3, 2017]
+ Require cmake-2.8.8 in CMakeLists.txt. Revised symlink creation,
+ no longer using deprecated cmake LOCATION feature (Clifford Yapp).
+ Fixed five-byte error in the calculation of IDAT maximum possible size.
+
+Version 1.6.32beta10 [August 5, 2017]
+ Moved chunk-length check into a png_check_chunk_length() private
+ function (Suggested by Max Stepin).
+ Moved bad pngs from tests to contrib/libtests/crashers
+ Moved testing of bad pngs into a separate tests/pngtest-badpngs script
+ Added the --xfail (expected FAIL) option to pngtest.c. It writes XFAIL
+ in the output but PASS for the libpng test.
+ Require cmake-3.0.2 in CMakeLists.txt (Clifford Yapp).
+ Fix "const" declaration info_ptr argument to png_get_eXIf_1() and the
+ num_exif argument to png_get_eXIf_1() (Github Issue 171).
+
+Version 1.6.32beta11 [August 7, 2017]
+ Added "eXIf" to "chunks_to_ignore[]" in png_set_keep_unknown_chunks().
+ Added huge_IDAT.png and empty_ancillary_chunks.png to testpngs/crashers.
+ Make pngtest --strict, --relax, --xfail options imply -m (multiple).
+ Removed unused chunk_name parameter from png_check_chunk_length().
+ Relocated setting free_me for eXIf data, to stop an OSS-fuzz leak.
+ Initialize profile_header[] in png_handle_iCCP() to fix OSS-fuzz issue.
+ Initialize png_ptr->row_buf[0] to 255 in png_read_row() to fix OSS-fuzz UMR.
+ Attempt to fix a UMR in png_set_text_2() to fix OSS-fuzz issue.
+ Increase minimum zlib stream from 9 to 14 in png_handle_iCCP(), to account
+ for the minimum 'deflate' stream, and relocate the test to a point
+ after the keyword has been read.
+ Check that the eXIf chunk has at least 2 bytes and begins with "II" or "MM".
+
+Version 1.6.32rc01 [August 18, 2017]
+ Added a set of "huge_xxxx_chunk.png" files to contrib/testpngs/crashers,
+ one for each known chunk type, with length = 2GB-1.
+ Check for 0 return from png_get_rowbytes() and added some (size_t) typecasts
+ in contrib/pngminus/*.c to stop some Coverity issues (162705, 162706,
+ and 162707).
+ Renamed chunks in contrib/testpngs/crashers to avoid having files whose
+ names differ only in case; this causes problems with some platforms
+ (github issue #172).
+
+Version 1.6.32rc02 [August 22, 2017]
+ Added contrib/oss-fuzz directory which contains files used by the oss-fuzz
+ project (https://github.com/google/oss-fuzz/tree/master/projects/libpng).
+
+Version 1.6.32 [August 24, 2017]
+ No changes.
+
+Version 1.6.33beta01 [August 28, 2017]
+ Added PNGMINUS_UNUSED macro to contrib/pngminus/p*.c and added missing
+ parenthesis in contrib/pngminus/pnm2png.c (bug report by Christian Hesse).
+ Fixed off-by-one error in png_do_check_palette_indexes() (Bug report
+ by Mick P., Source Forge Issue #269).
+
+Version 1.6.33beta02 [September 3, 2017]
+ Initialize png_handler.row_ptr in contrib/oss-fuzz/libpng_read_fuzzer.cc
+ to fix shortlived oss-fuzz issue 3234.
+ Compute a larger limit on IDAT because some applications write a deflate
+ buffer for each row (Bug report by Andrew Church).
+ Use current date (DATE) instead of release-date (RDATE) in last
+ changed date of contrib/oss-fuzz files.
+ Enabled ARM support in CMakeLists.txt (Bernd Kuhls).
+
+Version 1.6.33beta03 [September 14, 2017]
+ Fixed incorrect typecast of some arguments to png_malloc() and
+ png_calloc() that were png_uint_32 instead of png_alloc_size_t
+ (Bug report by "irwir" in Github libpng issue #175).
+ Use pnglibconf.h.prebuilt when building for ANDROID with cmake (Github
+ issue 162, by rcdailey).
+
+Version 1.6.33rc01 [September 20, 2017]
+ Initialize memory allocated by png_inflate to zero, using memset, to
+ stop an oss-fuzz "use of uninitialized value" detection in png_set_text_2()
+ due to truncated iTXt or zTXt chunk.
+ Initialize memory allocated by png_read_buffer to zero, using memset, to
+ stop an oss-fuzz "use of uninitialized value" detection in
+ png_icc_check_tag_table() due to truncated iCCP chunk.
+ Removed a redundant test (suggested by "irwir" in Github issue #180).
+
+Version 1.6.33rc02 [September 23, 2017]
+ Added an interlaced version of each file in contrib/pngsuite.
+ Relocate new memset() call in pngrutil.c.
+ Removed more redundant tests (suggested by "irwir" in Github issue #180).
+ Add support for loading images with associated alpha in the Simplified
+ API (Samuel Williams).
+
+Version 1.6.33 [September 28, 2017]
+ Revert contrib/oss-fuzz/libpng_read_fuzzer.cc to libpng-1.6.32 state.
+ Initialize png_handler.row_ptr in contrib/oss-fuzz/libpng_read_fuzzer.cc
+ Add end_info structure and png_read_end() to the libpng fuzzer.
+
+Version 1.6.34 [September 29, 2017]
+ Removed contrib/pngsuite/i*.png; some of these were incorrect and caused
+ test failures.
+
Send comments/corrections/commendations to png-mng-implement at lists.sf.net
(subscription required; visit
https://lists.sourceforge.net/lists/listinfo/png-mng-implement
diff --git a/plugins/AdvaImg/src/LibPNG/LICENSE b/plugins/AdvaImg/src/LibPNG/LICENSE index 028d49788f..8248a963e4 100644 --- a/plugins/AdvaImg/src/LibPNG/LICENSE +++ b/plugins/AdvaImg/src/LibPNG/LICENSE @@ -10,7 +10,7 @@ this sentence. This code is released under the libpng license.
-libpng versions 1.0.7, July 1, 2000 through 1.6.31, July 27, 2017 are
+libpng versions 1.0.7, July 1, 2000 through 1.6.34, September 29, 2017 are
Copyright (c) 2000-2002, 2004, 2006-2017 Glenn Randers-Pehrson, are
derived from libpng-1.0.6, and are distributed according to the same
disclaimer and license as libpng-1.0.6 with the following individuals
@@ -130,4 +130,4 @@ any encryption software. See the EAR, paragraphs 734.3(b)(3) and Glenn Randers-Pehrson
glennrp at users.sourceforge.net
-April 1, 2017
+September 29, 2017
diff --git a/plugins/AdvaImg/src/LibPNG/README b/plugins/AdvaImg/src/LibPNG/README index 87edc77615..59b6a5d0ea 100644 --- a/plugins/AdvaImg/src/LibPNG/README +++ b/plugins/AdvaImg/src/LibPNG/README @@ -1,4 +1,4 @@ -README for libpng version 1.6.31 - July 27, 2017 (shared library 16.0)
+README for libpng version 1.6.34 - September 29, 2017 (shared library 16.0)
See the note about version numbers near the top of png.h
See INSTALL for instructions on how to install libpng.
diff --git a/plugins/AdvaImg/src/LibPNG/configure b/plugins/AdvaImg/src/LibPNG/configure deleted file mode 100644 index e69de29bb2..0000000000 --- a/plugins/AdvaImg/src/LibPNG/configure +++ /dev/null diff --git a/plugins/AdvaImg/src/LibPNG/example.c b/plugins/AdvaImg/src/LibPNG/example.c deleted file mode 100644 index d0afe51c81..0000000000 --- a/plugins/AdvaImg/src/LibPNG/example.c +++ /dev/null @@ -1,1066 +0,0 @@ -
-#if 0 /* in case someone actually tries to compile this */
-
-/* example.c - an example of using libpng
- * Last changed in libpng 1.6.24 [August 4, 2016]
- * Maintained 1998-2016 Glenn Randers-Pehrson
- * Maintained 1996, 1997 Andreas Dilger)
- * Written 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
- * To the extent possible under law, the authors have waived
- * all copyright and related or neighboring rights to this file.
- * This work is published from: United States.
- */
-
-/* This is an example of how to use libpng to read and write PNG files.
- * The file libpng-manual.txt is much more verbose then this. If you have not
- * read it, do so first. This was designed to be a starting point of an
- * implementation. This is not officially part of libpng, is hereby placed
- * in the public domain, and therefore does not require a copyright notice.
- *
- * This file does not currently compile, because it is missing certain
- * parts, like allocating memory to hold an image. You will have to
- * supply these parts to get it to compile. For an example of a minimal
- * working PNG reader/writer, see pngtest.c, included in this distribution;
- * see also the programs in the contrib directory.
- */
-
-/* The simple, but restricted, approach to reading a PNG file or data stream
- * just requires two function calls, as in the following complete program.
- * Writing a file just needs one function call, so long as the data has an
- * appropriate layout.
- *
- * The following code reads PNG image data from a file and writes it, in a
- * potentially new format, to a new file. While this code will compile there is
- * minimal (insufficient) error checking; for a more realistic version look at
- * contrib/examples/pngtopng.c
- */
-#include <stddef.h>
-#include <stdlib.h>
-#include <string.h>
-#include <stdio.h>
-#include <png.h>
-#include <zlib.h>
-
-int main(int argc, const char **argv)
-{
- if (argc == 3)
- {
- png_image image; /* The control structure used by libpng */
-
- /* Initialize the 'png_image' structure. */
- memset(&image, 0, (sizeof image));
- image.version = PNG_IMAGE_VERSION;
-
- /* The first argument is the file to read: */
- if (png_image_begin_read_from_file(&image, argv[1]) != 0)
- {
- png_bytep buffer;
-
- /* Set the format in which to read the PNG file; this code chooses a
- * simple sRGB format with a non-associated alpha channel, adequate to
- * store most images.
- */
- image.format = PNG_FORMAT_RGBA;
-
- /* Now allocate enough memory to hold the image in this format; the
- * PNG_IMAGE_SIZE macro uses the information about the image (width,
- * height and format) stored in 'image'.
- */
- buffer = malloc(PNG_IMAGE_SIZE(image));
-
- /* If enough memory was available read the image in the desired format
- * then write the result out to the new file. 'background' is not
- * necessary when reading the image because the alpha channel is
- * preserved; if it were to be removed, for example if we requested
- * PNG_FORMAT_RGB, then either a solid background color would have to
- * be supplied or the output buffer would have to be initialized to the
- * actual background of the image.
- *
- * The fourth argument to png_image_finish_read is the 'row_stride' -
- * this is the number of components allocated for the image in each
- * row. It has to be at least as big as the value returned by
- * PNG_IMAGE_ROW_STRIDE, but if you just allocate space for the
- * default, minimum, size using PNG_IMAGE_SIZE as above you can pass
- * zero.
- *
- * The final argument is a pointer to a buffer for the colormap;
- * colormaps have exactly the same format as a row of image pixels (so
- * you choose what format to make the colormap by setting
- * image.format). A colormap is only returned if
- * PNG_FORMAT_FLAG_COLORMAP is also set in image.format, so in this
- * case NULL is passed as the final argument. If you do want to force
- * all images into an index/color-mapped format then you can use:
- *
- * PNG_IMAGE_COLORMAP_SIZE(image)
- *
- * to find the maximum size of the colormap in bytes.
- */
- if (buffer != NULL &&
- png_image_finish_read(&image, NULL/*background*/, buffer,
- 0/*row_stride*/, NULL/*colormap*/) != 0)
- {
- /* Now write the image out to the second argument. In the write
- * call 'convert_to_8bit' allows 16-bit data to be squashed down to
- * 8 bits; this isn't necessary here because the original read was
- * to the 8-bit format.
- */
- if (png_image_write_to_file(&image, argv[2], 0/*convert_to_8bit*/,
- buffer, 0/*row_stride*/, NULL/*colormap*/) != 0)
- {
- /* The image has been written successfully. */
- exit(0);
- }
- }
-
- else
- {
- /* Calling png_image_free is optional unless the simplified API was
- * not run to completion. In this case if there wasn't enough
- * memory for 'buffer' we didn't complete the read, so we must free
- * the image:
- */
- if (buffer == NULL)
- png_image_free(&image);
-
- else
- free(buffer);
- }
-
- /* Something went wrong reading or writing the image. libpng stores a
- * textual message in the 'png_image' structure:
- */
- fprintf(stderr, "pngtopng: error: %s\n", image.message);
- exit (1);
- }
-
- fprintf(stderr, "pngtopng: usage: pngtopng input-file output-file\n");
- exit(1);
-}
-
-/* That's it ;-) Of course you probably want to do more with PNG files than
- * just converting them all to 32-bit RGBA PNG files; you can do that between
- * the call to png_image_finish_read and png_image_write_to_file. You can also
- * ask for the image data to be presented in a number of different formats. You
- * do this by simply changing the 'format' parameter set before allocating the
- * buffer.
- *
- * The format parameter consists of five flags that define various aspects of
- * the image, you can simply add these together to get the format or you can use
- * one of the predefined macros from png.h (as above):
- *
- * PNG_FORMAT_FLAG_COLOR: if set the image will have three color components per
- * pixel (red, green and blue), if not set the image will just have one
- * luminance (grayscale) component.
- *
- * PNG_FORMAT_FLAG_ALPHA: if set each pixel in the image will have an additional
- * alpha value; a linear value that describes the degree the image pixel
- * covers (overwrites) the contents of the existing pixel on the display.
- *
- * PNG_FORMAT_FLAG_LINEAR: if set the components of each pixel will be returned
- * as a series of 16-bit linear values, if not set the components will be
- * returned as a series of 8-bit values encoded according to the 'sRGB'
- * standard. The 8-bit format is the normal format for images intended for
- * direct display, because almost all display devices do the inverse of the
- * sRGB transformation to the data they receive. The 16-bit format is more
- * common for scientific data and image data that must be further processed;
- * because it is linear simple math can be done on the component values.
- * Regardless of the setting of this flag the alpha channel is always linear,
- * although it will be 8 bits or 16 bits wide as specified by the flag.
- *
- * PNG_FORMAT_FLAG_BGR: if set the components of a color pixel will be returned
- * in the order blue, then green, then red. If not set the pixel components
- * are in the order red, then green, then blue.
- *
- * PNG_FORMAT_FLAG_AFIRST: if set the alpha channel (if present) precedes the
- * color or grayscale components. If not set the alpha channel follows the
- * components.
- *
- * You do not have to read directly from a file. You can read from memory or,
- * on systems that support it, from a <stdio.h> FILE*. This is controlled by
- * the particular png_image_read_from_ function you call at the start. Likewise
- * on write you can write to a FILE* if your system supports it. Check the
- * macro PNG_STDIO_SUPPORTED to see if stdio support has been included in your
- * libpng build.
- *
- * If you read 16-bit (PNG_FORMAT_FLAG_LINEAR) data you may need to write it in
- * the 8-bit format for display. You do this by setting the convert_to_8bit
- * flag to 'true'.
- *
- * Don't repeatedly convert between the 8-bit and 16-bit forms. There is
- * significant data loss when 16-bit data is converted to the 8-bit encoding and
- * the current libpng implementation of conversion to 16-bit is also
- * significantly lossy. The latter will be fixed in the future, but the former
- * is unavoidable - the 8-bit format just doesn't have enough resolution.
- */
-
-/* If your program needs more information from the PNG data it reads, or if you
- * need to do more complex transformations, or minimize transformations, on the
- * data you read, then you must use one of the several lower level libpng
- * interfaces.
- *
- * All these interfaces require that you do your own error handling - your
- * program must be able to arrange for control to return to your own code any
- * time libpng encounters a problem. There are several ways to do this, but the
- * standard way is to use the ANSI-C (C90) <setjmp.h> interface to establish a
- * return point within your own code. You must do this if you do not use the
- * simplified interface (above).
- *
- * The first step is to include the header files you need, including the libpng
- * header file. Include any standard headers and feature test macros your
- * program requires before including png.h:
- */
-#include <png.h>
-
- /* The png_jmpbuf() macro, used in error handling, became available in
- * libpng version 1.0.6. If you want to be able to run your code with older
- * versions of libpng, you must define the macro yourself (but only if it
- * is not already defined by libpng!).
- */
-
-#ifndef png_jmpbuf
-# define png_jmpbuf(png_ptr) ((png_ptr)->png_jmpbuf)
-#endif
-
-/* Check to see if a file is a PNG file using png_sig_cmp(). png_sig_cmp()
- * returns zero if the image is a PNG and nonzero if it isn't a PNG.
- *
- * The function check_if_png() shown here, but not used, returns nonzero (true)
- * if the file can be opened and is a PNG, 0 (false) otherwise.
- *
- * If this call is successful, and you are going to keep the file open,
- * you should call png_set_sig_bytes(png_ptr, PNG_BYTES_TO_CHECK); once
- * you have created the png_ptr, so that libpng knows your application
- * has read that many bytes from the start of the file. Make sure you
- * don't call png_set_sig_bytes() with more than 8 bytes read or give it
- * an incorrect number of bytes read, or you will either have read too
- * many bytes (your fault), or you are telling libpng to read the wrong
- * number of magic bytes (also your fault).
- *
- * Many applications already read the first 2 or 4 bytes from the start
- * of the image to determine the file type, so it would be easiest just
- * to pass the bytes to png_sig_cmp() or even skip that if you know
- * you have a PNG file, and call png_set_sig_bytes().
- */
-#define PNG_BYTES_TO_CHECK 4
-int check_if_png(char *file_name, FILE **fp)
-{
- char buf[PNG_BYTES_TO_CHECK];
-
- /* Open the prospective PNG file. */
- if ((*fp = fopen(file_name, "rb")) == NULL)
- return 0;
-
- /* Read in some of the signature bytes */
- if (fread(buf, 1, PNG_BYTES_TO_CHECK, *fp) != PNG_BYTES_TO_CHECK)
- return 0;
-
- /* Compare the first PNG_BYTES_TO_CHECK bytes of the signature.
- Return nonzero (true) if they match */
-
- return(!png_sig_cmp(buf, (png_size_t)0, PNG_BYTES_TO_CHECK));
-}
-
-/* Read a PNG file. You may want to return an error code if the read
- * fails (depending upon the failure). There are two "prototypes" given
- * here - one where we are given the filename, and we need to open the
- * file, and the other where we are given an open file (possibly with
- * some or all of the magic bytes read - see comments above).
- */
-#ifdef open_file /* prototype 1 */
-void read_png(char *file_name) /* We need to open the file */
-{
- png_structp png_ptr;
- png_infop info_ptr;
- int sig_read = 0;
- png_uint_32 width, height;
- int bit_depth, color_type, interlace_type;
- FILE *fp;
-
- if ((fp = fopen(file_name, "rb")) == NULL)
- return (ERROR);
-
-#else no_open_file /* prototype 2 */
-void read_png(FILE *fp, int sig_read) /* File is already open */
-{
- png_structp png_ptr;
- png_infop info_ptr;
- png_uint_32 width, height;
- int bit_depth, color_type, interlace_type;
-#endif no_open_file /* Only use one prototype! */
-
- /* Create and initialize the png_struct with the desired error handler
- * functions. If you want to use the default stderr and longjump method,
- * you can supply NULL for the last three parameters. We also supply the
- * the compiler header file version, so that we know if the application
- * was compiled with a compatible version of the library. REQUIRED
- */
- png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
- png_voidp user_error_ptr, user_error_fn, user_warning_fn);
-
- if (png_ptr == NULL)
- {
- fclose(fp);
- return (ERROR);
- }
-
- /* Allocate/initialize the memory for image information. REQUIRED. */
- info_ptr = png_create_info_struct(png_ptr);
- if (info_ptr == NULL)
- {
- fclose(fp);
- png_destroy_read_struct(&png_ptr, NULL, NULL);
- return (ERROR);
- }
-
- /* Set error handling if you are using the setjmp/longjmp method (this is
- * the normal method of doing things with libpng). REQUIRED unless you
- * set up your own error handlers in the png_create_read_struct() earlier.
- */
-
- if (setjmp(png_jmpbuf(png_ptr)))
- {
- /* Free all of the memory associated with the png_ptr and info_ptr */
- png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
- fclose(fp);
- /* If we get here, we had a problem reading the file */
- return (ERROR);
- }
-
- /* One of the following I/O initialization methods is REQUIRED */
-#ifdef streams /* PNG file I/O method 1 */
- /* Set up the input control if you are using standard C streams */
- png_init_io(png_ptr, fp);
-
-#else no_streams /* PNG file I/O method 2 */
- /* If you are using replacement read functions, instead of calling
- * png_init_io() here you would call:
- */
- png_set_read_fn(png_ptr, (void *)user_io_ptr, user_read_fn);
- /* where user_io_ptr is a structure you want available to the callbacks */
-#endif no_streams /* Use only one I/O method! */
-
- /* If we have already read some of the signature */
- png_set_sig_bytes(png_ptr, sig_read);
-
-#ifdef hilevel
- /*
- * If you have enough memory to read in the entire image at once,
- * and you need to specify only transforms that can be controlled
- * with one of the PNG_TRANSFORM_* bits (this presently excludes
- * quantizing, filling, setting background, and doing gamma
- * adjustment), then you can read the entire image (including
- * pixels) into the info structure with this call:
- */
- png_read_png(png_ptr, info_ptr, png_transforms, NULL);
-
-#else
- /* OK, you're doing it the hard way, with the lower-level functions */
-
- /* The call to png_read_info() gives us all of the information from the
- * PNG file before the first IDAT (image data chunk). REQUIRED
- */
- png_read_info(png_ptr, info_ptr);
-
- png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
- &interlace_type, NULL, NULL);
-
- /* Set up the data transformations you want. Note that these are all
- * optional. Only call them if you want/need them. Many of the
- * transformations only work on specific types of images, and many
- * are mutually exclusive.
- */
-
- /* Tell libpng to strip 16 bits/color files down to 8 bits/color.
- * Use accurate scaling if it's available, otherwise just chop off the
- * low byte.
- */
-#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
- png_set_scale_16(png_ptr);
-#else
- png_set_strip_16(png_ptr);
-#endif
-
- /* Strip alpha bytes from the input data without combining with the
- * background (not recommended).
- */
- png_set_strip_alpha(png_ptr);
-
- /* Extract multiple pixels with bit depths of 1, 2, and 4 from a single
- * byte into separate bytes (useful for paletted and grayscale images).
- */
- png_set_packing(png_ptr);
-
- /* Change the order of packed pixels to least significant bit first
- * (not useful if you are using png_set_packing). */
- png_set_packswap(png_ptr);
-
- /* Expand paletted colors into true RGB triplets */
- if (color_type == PNG_COLOR_TYPE_PALETTE)
- png_set_palette_to_rgb(png_ptr);
-
- /* Expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel */
- if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
- png_set_expand_gray_1_2_4_to_8(png_ptr);
-
- /* Expand paletted or RGB images with transparency to full alpha channels
- * so the data will be available as RGBA quartets.
- */
- if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS) != 0)
- png_set_tRNS_to_alpha(png_ptr);
-
- /* Set the background color to draw transparent and alpha images over.
- * It is possible to set the red, green, and blue components directly
- * for paletted images instead of supplying a palette index. Note that
- * even if the PNG file supplies a background, you are not required to
- * use it - you should use the (solid) application background if it has one.
- */
-
- png_color_16 my_background, *image_background;
-
- if (png_get_bKGD(png_ptr, info_ptr, &image_background) != 0)
- png_set_background(png_ptr, image_background,
- PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
- else
- png_set_background(png_ptr, &my_background,
- PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
-
- /* Some suggestions as to how to get a screen gamma value
- *
- * Note that screen gamma is the display_exponent, which includes
- * the CRT_exponent and any correction for viewing conditions
- */
- if (/* We have a user-defined screen gamma value */)
- {
- screen_gamma = user-defined screen_gamma;
- }
- /* This is one way that applications share the same screen gamma value */
- else if ((gamma_str = getenv("SCREEN_GAMMA")) != NULL)
- {
- screen_gamma = atof(gamma_str);
- }
- /* If we don't have another value */
- else
- {
- screen_gamma = PNG_DEFAULT_sRGB; /* A good guess for a PC monitor
- in a dimly lit room */
- screen_gamma = PNG_GAMMA_MAC_18 or 1.0; /* Good guesses for Mac systems */
- }
-
- /* Tell libpng to handle the gamma conversion for you. The final call
- * is a good guess for PC generated images, but it should be configurable
- * by the user at run time by the user. It is strongly suggested that
- * your application support gamma correction.
- */
-
- int intent;
-
- if (png_get_sRGB(png_ptr, info_ptr, &intent) != 0)
- png_set_gamma(png_ptr, screen_gamma, PNG_DEFAULT_sRGB);
- else
- {
- double image_gamma;
- if (png_get_gAMA(png_ptr, info_ptr, &image_gamma) != 0)
- png_set_gamma(png_ptr, screen_gamma, image_gamma);
- else
- png_set_gamma(png_ptr, screen_gamma, 0.45455);
- }
-
-#ifdef PNG_READ_QUANTIZE_SUPPORTED
- /* Quantize RGB files down to 8-bit palette or reduce palettes
- * to the number of colors available on your screen.
- */
- if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
- {
- int num_palette;
- png_colorp palette;
-
- /* This reduces the image to the application supplied palette */
- if (/* We have our own palette */)
- {
- /* An array of colors to which the image should be quantized */
- png_color std_color_cube[MAX_SCREEN_COLORS];
-
- png_set_quantize(png_ptr, std_color_cube, MAX_SCREEN_COLORS,
- MAX_SCREEN_COLORS, NULL, 0);
- }
- /* This reduces the image to the palette supplied in the file */
- else if (png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette) != 0)
- {
- png_uint_16p histogram = NULL;
-
- png_get_hIST(png_ptr, info_ptr, &histogram);
-
- png_set_quantize(png_ptr, palette, num_palette,
- max_screen_colors, histogram, 0);
- }
- }
-#endif /* READ_QUANTIZE */
-
- /* Invert monochrome files to have 0 as white and 1 as black */
- png_set_invert_mono(png_ptr);
-
- /* If you want to shift the pixel values from the range [0,255] or
- * [0,65535] to the original [0,7] or [0,31], or whatever range the
- * colors were originally in:
- */
- if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT) != 0)
- {
- png_color_8p sig_bit_p;
-
- png_get_sBIT(png_ptr, info_ptr, &sig_bit_p);
- png_set_shift(png_ptr, sig_bit_p);
- }
-
- /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
- if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
- png_set_bgr(png_ptr);
-
- /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
- png_set_swap_alpha(png_ptr);
-
- /* Swap bytes of 16-bit files to least significant byte first */
- png_set_swap(png_ptr);
-
- /* Add filler (or alpha) byte (before/after each RGB triplet) */
- png_set_filler(png_ptr, 0xffff, PNG_FILLER_AFTER);
-
-#ifdef PNG_READ_INTERLACING_SUPPORTED
- /* Turn on interlace handling. REQUIRED if you are not using
- * png_read_image(). To see how to handle interlacing passes,
- * see the png_read_row() method below:
- */
- number_passes = png_set_interlace_handling(png_ptr);
-#else /* !READ_INTERLACING */
- number_passes = 1;
-#endif /* READ_INTERLACING */
-
-
- /* Optional call to gamma correct and add the background to the palette
- * and update info structure. REQUIRED if you are expecting libpng to
- * update the palette for you (ie you selected such a transform above).
- */
- png_read_update_info(png_ptr, info_ptr);
-
- /* Allocate the memory to hold the image using the fields of info_ptr. */
-
- /* The easiest way to read the image: */
- png_bytep row_pointers[height];
-
- /* Clear the pointer array */
- for (row = 0; row < height; row++)
- row_pointers[row] = NULL;
-
- for (row = 0; row < height; row++)
- row_pointers[row] = png_malloc(png_ptr, png_get_rowbytes(png_ptr,
- info_ptr));
-
- /* Now it's time to read the image. One of these methods is REQUIRED */
-#ifdef entire /* Read the entire image in one go */
- png_read_image(png_ptr, row_pointers);
-
-#else no_entire /* Read the image one or more scanlines at a time */
- /* The other way to read images - deal with interlacing: */
-
- for (pass = 0; pass < number_passes; pass++)
- {
-#ifdef single /* Read the image a single row at a time */
- for (y = 0; y < height; y++)
- {
- png_read_rows(png_ptr, &row_pointers[y], NULL, 1);
- }
-
-#else no_single /* Read the image several rows at a time */
- for (y = 0; y < height; y += number_of_rows)
- {
-#ifdef sparkle /* Read the image using the "sparkle" effect. */
- png_read_rows(png_ptr, &row_pointers[y], NULL,
- number_of_rows);
-#else no_sparkle /* Read the image using the "rectangle" effect */
- png_read_rows(png_ptr, NULL, &row_pointers[y],
- number_of_rows);
-#endif no_sparkle /* Use only one of these two methods */
- }
-
- /* If you want to display the image after every pass, do so here */
-#endif no_single /* Use only one of these two methods */
- }
-#endif no_entire /* Use only one of these two methods */
-
- /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
- png_read_end(png_ptr, info_ptr);
-#endif hilevel
-
- /* At this point you have read the entire image */
-
- /* Clean up after the read, and free any memory allocated - REQUIRED */
- png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
-
- /* Close the file */
- fclose(fp);
-
- /* That's it */
- return (OK);
-}
-
-/* Progressively read a file */
-
-int
-initialize_png_reader(png_structp *png_ptr, png_infop *info_ptr)
-{
- /* Create and initialize the png_struct with the desired error handler
- * functions. If you want to use the default stderr and longjump method,
- * you can supply NULL for the last three parameters. We also check that
- * the library version is compatible in case we are using dynamically
- * linked libraries.
- */
- *png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
- png_voidp user_error_ptr, user_error_fn, user_warning_fn);
-
- if (*png_ptr == NULL)
- {
- *info_ptr = NULL;
- return (ERROR);
- }
-
- *info_ptr = png_create_info_struct(png_ptr);
-
- if (*info_ptr == NULL)
- {
- png_destroy_read_struct(png_ptr, info_ptr, NULL);
- return (ERROR);
- }
-
- if (setjmp(png_jmpbuf((*png_ptr))))
- {
- png_destroy_read_struct(png_ptr, info_ptr, NULL);
- return (ERROR);
- }
-
- /* This one's new. You will need to provide all three
- * function callbacks, even if you aren't using them all.
- * If you aren't using all functions, you can specify NULL
- * parameters. Even when all three functions are NULL,
- * you need to call png_set_progressive_read_fn().
- * These functions shouldn't be dependent on global or
- * static variables if you are decoding several images
- * simultaneously. You should store stream specific data
- * in a separate struct, given as the second parameter,
- * and retrieve the pointer from inside the callbacks using
- * the function png_get_progressive_ptr(png_ptr).
- */
- png_set_progressive_read_fn(*png_ptr, (void *)stream_data,
- info_callback, row_callback, end_callback);
-
- return (OK);
-}
-
-int
-process_data(png_structp *png_ptr, png_infop *info_ptr,
- png_bytep buffer, png_uint_32 length)
-{
- if (setjmp(png_jmpbuf((*png_ptr))))
- {
- /* Free the png_ptr and info_ptr memory on error */
- png_destroy_read_struct(png_ptr, info_ptr, NULL);
- return (ERROR);
- }
-
- /* This one's new also. Simply give it chunks of data as
- * they arrive from the data stream (in order, of course).
- * On segmented machines, don't give it any more than 64K.
- * The library seems to run fine with sizes of 4K, although
- * you can give it much less if necessary (I assume you can
- * give it chunks of 1 byte, but I haven't tried with less
- * than 256 bytes yet). When this function returns, you may
- * want to display any rows that were generated in the row
- * callback, if you aren't already displaying them there.
- */
- png_process_data(*png_ptr, *info_ptr, buffer, length);
- return (OK);
-}
-
-info_callback(png_structp png_ptr, png_infop info)
-{
- /* Do any setup here, including setting any of the transformations
- * mentioned in the Reading PNG files section. For now, you _must_
- * call either png_start_read_image() or png_read_update_info()
- * after all the transformations are set (even if you don't set
- * any). You may start getting rows before png_process_data()
- * returns, so this is your last chance to prepare for that.
- */
-}
-
-row_callback(png_structp png_ptr, png_bytep new_row,
- png_uint_32 row_num, int pass)
-{
- /*
- * This function is called for every row in the image. If the
- * image is interlaced, and you turned on the interlace handler,
- * this function will be called for every row in every pass.
- *
- * In this function you will receive a pointer to new row data from
- * libpng called new_row that is to replace a corresponding row (of
- * the same data format) in a buffer allocated by your application.
- *
- * The new row data pointer "new_row" may be NULL, indicating there is
- * no new data to be replaced (in cases of interlace loading).
- *
- * If new_row is not NULL then you need to call
- * png_progressive_combine_row() to replace the corresponding row as
- * shown below:
- */
-
- /* Get pointer to corresponding row in our
- * PNG read buffer.
- */
- png_bytep old_row = ((png_bytep *)our_data)[row_num];
-
-#ifdef PNG_READ_INTERLACING_SUPPORTED
- /* If both rows are allocated then copy the new row
- * data to the corresponding row data.
- */
- if ((old_row != NULL) && (new_row != NULL))
- png_progressive_combine_row(png_ptr, old_row, new_row);
-
- /*
- * The rows and passes are called in order, so you don't really
- * need the row_num and pass, but I'm supplying them because it
- * may make your life easier.
- *
- * For the non-NULL rows of interlaced images, you must call
- * png_progressive_combine_row() passing in the new row and the
- * old row, as demonstrated above. You can call this function for
- * NULL rows (it will just return) and for non-interlaced images
- * (it just does the memcpy for you) if it will make the code
- * easier. Thus, you can just do this for all cases:
- */
-
- png_progressive_combine_row(png_ptr, old_row, new_row);
-
- /* where old_row is what was displayed for previous rows. Note
- * that the first pass (pass == 0 really) will completely cover
- * the old row, so the rows do not have to be initialized. After
- * the first pass (and only for interlaced images), you will have
- * to pass the current row as new_row, and the function will combine
- * the old row and the new row.
- */
-#endif /* READ_INTERLACING */
-}
-
-end_callback(png_structp png_ptr, png_infop info)
-{
- /* This function is called when the whole image has been read,
- * including any chunks after the image (up to and including
- * the IEND). You will usually have the same info chunk as you
- * had in the header, although some data may have been added
- * to the comments and time fields.
- *
- * Most people won't do much here, perhaps setting a flag that
- * marks the image as finished.
- */
-}
-
-/* Write a png file */
-void write_png(char *file_name /* , ... other image information ... */)
-{
- FILE *fp;
- png_structp png_ptr;
- png_infop info_ptr;
- png_colorp palette;
-
- /* Open the file */
- fp = fopen(file_name, "wb");
- if (fp == NULL)
- return (ERROR);
-
- /* Create and initialize the png_struct with the desired error handler
- * functions. If you want to use the default stderr and longjump method,
- * you can supply NULL for the last three parameters. We also check that
- * the library version is compatible with the one used at compile time,
- * in case we are using dynamically linked libraries. REQUIRED.
- */
- png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,
- png_voidp user_error_ptr, user_error_fn, user_warning_fn);
-
- if (png_ptr == NULL)
- {
- fclose(fp);
- return (ERROR);
- }
-
- /* Allocate/initialize the image information data. REQUIRED */
- info_ptr = png_create_info_struct(png_ptr);
- if (info_ptr == NULL)
- {
- fclose(fp);
- png_destroy_write_struct(&png_ptr, NULL);
- return (ERROR);
- }
-
- /* Set error handling. REQUIRED if you aren't supplying your own
- * error handling functions in the png_create_write_struct() call.
- */
- if (setjmp(png_jmpbuf(png_ptr)))
- {
- /* If we get here, we had a problem writing the file */
- fclose(fp);
- png_destroy_write_struct(&png_ptr, &info_ptr);
- return (ERROR);
- }
-
- /* One of the following I/O initialization functions is REQUIRED */
-
-#ifdef streams /* I/O initialization method 1 */
- /* Set up the output control if you are using standard C streams */
- png_init_io(png_ptr, fp);
-
-#else no_streams /* I/O initialization method 2 */
- /* If you are using replacement write functions, instead of calling
- * png_init_io() here you would call
- */
- png_set_write_fn(png_ptr, (void *)user_io_ptr, user_write_fn,
- user_IO_flush_function);
- /* where user_io_ptr is a structure you want available to the callbacks */
-#endif no_streams /* Only use one initialization method */
-
-#ifdef hilevel
- /* This is the easy way. Use it if you already have all the
- * image info living in the structure. You could "|" many
- * PNG_TRANSFORM flags into the png_transforms integer here.
- */
- png_write_png(png_ptr, info_ptr, png_transforms, NULL);
-
-#else
- /* This is the hard way */
-
- /* Set the image information here. Width and height are up to 2^31,
- * bit_depth is one of 1, 2, 4, 8, or 16, but valid values also depend on
- * the color_type selected. color_type is one of PNG_COLOR_TYPE_GRAY,
- * PNG_COLOR_TYPE_GRAY_ALPHA, PNG_COLOR_TYPE_PALETTE, PNG_COLOR_TYPE_RGB,
- * or PNG_COLOR_TYPE_RGB_ALPHA. interlace is either PNG_INTERLACE_NONE or
- * PNG_INTERLACE_ADAM7, and the compression_type and filter_type MUST
- * currently be PNG_COMPRESSION_TYPE_BASE and PNG_FILTER_TYPE_BASE. REQUIRED
- */
- png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, PNG_COLOR_TYPE_???,
- PNG_INTERLACE_????, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
-
- /* Set the palette if there is one. REQUIRED for indexed-color images */
- palette = (png_colorp)png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH
- * (sizeof (png_color)));
- /* ... Set palette colors ... */
- png_set_PLTE(png_ptr, info_ptr, palette, PNG_MAX_PALETTE_LENGTH);
- /* You must not free palette here, because png_set_PLTE only makes a link to
- * the palette that you malloced. Wait until you are about to destroy
- * the png structure.
- */
-
- /* Optional significant bit (sBIT) chunk */
- png_color_8 sig_bit;
-
- /* If we are dealing with a grayscale image then */
- sig_bit.gray = true_bit_depth;
-
- /* Otherwise, if we are dealing with a color image then */
- sig_bit.red = true_red_bit_depth;
- sig_bit.green = true_green_bit_depth;
- sig_bit.blue = true_blue_bit_depth;
-
- /* If the image has an alpha channel then */
- sig_bit.alpha = true_alpha_bit_depth;
-
- png_set_sBIT(png_ptr, info_ptr, &sig_bit);
-
-
- /* Optional gamma chunk is strongly suggested if you have any guess
- * as to the correct gamma of the image.
- */
- png_set_gAMA(png_ptr, info_ptr, gamma);
-
- /* Optionally write comments into the image */
- {
- png_text text_ptr[3];
-
- char key0[]="Title";
- char text0[]="Mona Lisa";
- text_ptr[0].key = key0;
- text_ptr[0].text = text0;
- text_ptr[0].compression = PNG_TEXT_COMPRESSION_NONE;
- text_ptr[0].itxt_length = 0;
- text_ptr[0].lang = NULL;
- text_ptr[0].lang_key = NULL;
-
- char key1[]="Author";
- char text1[]="Leonardo DaVinci";
- text_ptr[1].key = key1;
- text_ptr[1].text = text1;
- text_ptr[1].compression = PNG_TEXT_COMPRESSION_NONE;
- text_ptr[1].itxt_length = 0;
- text_ptr[1].lang = NULL;
- text_ptr[1].lang_key = NULL;
-
- char key2[]="Description";
- char text2[]="<long text>";
- text_ptr[2].key = key2;
- text_ptr[2].text = text2;
- text_ptr[2].compression = PNG_TEXT_COMPRESSION_zTXt;
- text_ptr[2].itxt_length = 0;
- text_ptr[2].lang = NULL;
- text_ptr[2].lang_key = NULL;
-
- png_set_text(write_ptr, write_info_ptr, text_ptr, 3);
- }
-
- /* Other optional chunks like cHRM, bKGD, tRNS, tIME, oFFs, pHYs */
-
- /* Note that if sRGB is present the gAMA and cHRM chunks must be ignored
- * on read and, if your application chooses to write them, they must
- * be written in accordance with the sRGB profile
- */
-
- /* Write the file header information. REQUIRED */
- png_write_info(png_ptr, info_ptr);
-
- /* If you want, you can write the info in two steps, in case you need to
- * write your private chunk ahead of PLTE:
- *
- * png_write_info_before_PLTE(write_ptr, write_info_ptr);
- * write_my_chunk();
- * png_write_info(png_ptr, info_ptr);
- *
- * However, given the level of known- and unknown-chunk support in 1.2.0
- * and up, this should no longer be necessary.
- */
-
- /* Once we write out the header, the compression type on the text
- * chunk gets changed to PNG_TEXT_COMPRESSION_NONE_WR or
- * PNG_TEXT_COMPRESSION_zTXt_WR, so it doesn't get written out again
- * at the end.
- */
-
- /* Set up the transformations you want. Note that these are
- * all optional. Only call them if you want them.
- */
-
- /* Invert monochrome pixels */
- png_set_invert_mono(png_ptr);
-
- /* Shift the pixels up to a legal bit depth and fill in
- * as appropriate to correctly scale the image.
- */
- png_set_shift(png_ptr, &sig_bit);
-
- /* Pack pixels into bytes */
- png_set_packing(png_ptr);
-
- /* Swap location of alpha bytes from ARGB to RGBA */
- png_set_swap_alpha(png_ptr);
-
- /* Get rid of filler (OR ALPHA) bytes, pack XRGB/RGBX/ARGB/RGBA into
- * RGB (4 channels -> 3 channels). The second parameter is not used.
- */
- png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
-
- /* Flip BGR pixels to RGB */
- png_set_bgr(png_ptr);
-
- /* Swap bytes of 16-bit files to most significant byte first */
- png_set_swap(png_ptr);
-
- /* Swap bits of 1-bit, 2-bit, 4-bit packed pixel formats */
- png_set_packswap(png_ptr);
-
- /* Turn on interlace handling if you are not using png_write_image() */
- if (interlacing != 0)
- number_passes = png_set_interlace_handling(png_ptr);
-
- else
- number_passes = 1;
-
- /* The easiest way to write the image (you may have a different memory
- * layout, however, so choose what fits your needs best). You need to
- * use the first method if you aren't handling interlacing yourself.
- */
- png_uint_32 k, height, width;
-
- /* In this example, "image" is a one-dimensional array of bytes */
-
- /* Guard against integer overflow */
- if (height > PNG_SIZE_MAX/(width*bytes_per_pixel)) {
- png_error(png_ptr, "Image_data buffer would be too large");
- }
- png_byte image[height*width*bytes_per_pixel];
-
- png_bytep row_pointers[height];
-
- if (height > PNG_UINT_32_MAX/(sizeof (png_bytep)))
- png_error (png_ptr, "Image is too tall to process in memory");
-
- /* Set up pointers into your "image" byte array */
- for (k = 0; k < height; k++)
- row_pointers[k] = image + k*width*bytes_per_pixel;
-
- /* One of the following output methods is REQUIRED */
-
-#ifdef entire /* Write out the entire image data in one call */
- png_write_image(png_ptr, row_pointers);
-
- /* The other way to write the image - deal with interlacing */
-
-#else no_entire /* Write out the image data by one or more scanlines */
-
- /* The number of passes is either 1 for non-interlaced images,
- * or 7 for interlaced images.
- */
- for (pass = 0; pass < number_passes; pass++)
- {
- /* Write a few rows at a time. */
- png_write_rows(png_ptr, &row_pointers[first_row], number_of_rows);
-
- /* If you are only writing one row at a time, this works */
- for (y = 0; y < height; y++)
- png_write_rows(png_ptr, &row_pointers[y], 1);
- }
-#endif no_entire /* Use only one output method */
-
- /* You can write optional chunks like tEXt, zTXt, and tIME at the end
- * as well. Shouldn't be necessary in 1.2.0 and up as all the public
- * chunks are supported and you can use png_set_unknown_chunks() to
- * register unknown chunks into the info structure to be written out.
- */
-
- /* It is REQUIRED to call this to finish writing the rest of the file */
- png_write_end(png_ptr, info_ptr);
-#endif hilevel
-
- /* If you png_malloced a palette, free it here (don't free info_ptr->palette,
- * as recommended in versions 1.0.5m and earlier of this example; if
- * libpng mallocs info_ptr->palette, libpng will free it). If you
- * allocated it with malloc() instead of png_malloc(), use free() instead
- * of png_free().
- */
- png_free(png_ptr, palette);
- palette = NULL;
-
- /* Similarly, if you png_malloced any data that you passed in with
- * png_set_something(), such as a hist or trans array, free it here,
- * when you can be sure that libpng is through with it.
- */
- png_free(png_ptr, trans);
- trans = NULL;
- /* Whenever you use png_free() it is a good idea to set the pointer to
- * NULL in case your application inadvertently tries to png_free() it
- * again. When png_free() sees a NULL it returns without action, thus
- * avoiding the double-free security problem.
- */
-
- /* Clean up after the write, and free any memory allocated */
- png_destroy_write_struct(&png_ptr, &info_ptr);
-
- /* Close the file */
- fclose(fp);
-
- /* That's it */
- return (OK);
-}
-
-#endif /* if 0 */
diff --git a/plugins/AdvaImg/src/LibPNG/libpng-manual.txt b/plugins/AdvaImg/src/LibPNG/libpng-manual.txt index e62905ae50..7007673175 100644 --- a/plugins/AdvaImg/src/LibPNG/libpng-manual.txt +++ b/plugins/AdvaImg/src/LibPNG/libpng-manual.txt @@ -1,6 +1,6 @@ libpng-manual.txt - A description on how to use and modify libpng
- libpng version 1.6.31 - July 27, 2017
+ libpng version 1.6.34 - September 29, 2017
Updated and distributed by Glenn Randers-Pehrson
<glennrp at users.sourceforge.net>
Copyright (c) 1998-2017 Glenn Randers-Pehrson
@@ -11,7 +11,7 @@ libpng-manual.txt - A description on how to use and modify libpng Based on:
- libpng versions 0.97, January 1998, through 1.6.31 - July 27, 2017
+ libpng versions 0.97, January 1998, through 1.6.34 - September 29, 2017
Updated and distributed by Glenn Randers-Pehrson
Copyright (c) 1998-2017 Glenn Randers-Pehrson
@@ -688,8 +688,9 @@ where 0x7fffffffL means unlimited. You can retrieve this limit with chunk_cache_max = png_get_chunk_cache_max(png_ptr);
Libpng imposes a limit of 8 Megabytes (8,000,000 bytes) on the amount of
-memory that a compressed chunk other than IDAT can occupy, when decompressed.
-You can change this limit with
+memory that any chunk other than IDAT can occupy, originally or when
+decompressed (prior to libpng-1.6.32 the limit was only applied to compressed
+chunks after decompression). You can change this limit with
png_set_chunk_malloc_max(png_ptr, user_chunk_malloc_max);
@@ -985,8 +986,17 @@ premultiplication. png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
-This is the default libpng handling of the alpha channel - it is not
-pre-multiplied into the color components. In addition the call states
+Choices for the alpha_mode are
+
+ PNG_ALPHA_PNG 0 /* according to the PNG standard */
+ PNG_ALPHA_STANDARD 1 /* according to Porter/Duff */
+ PNG_ALPHA_ASSOCIATED 1 /* as above; this is the normal practice */
+ PNG_ALPHA_PREMULTIPLIED 1 /* as above */
+ PNG_ALPHA_OPTIMIZED 2 /* 'PNG' for opaque pixels, else 'STANDARD' */
+ PNG_ALPHA_BROKEN 3 /* the alpha channel is gamma encoded */
+
+PNG_ALPHA_PNG is the default libpng handling of the alpha channel. It is not
+pre-multiplied into the color components. In addition the call states
that the output is for a sRGB system and causes all PNG files without gAMA
chunks to be assumed to be encoded using sRGB.
@@ -1001,7 +1011,7 @@ early Mac systems behaved. This is the classic Jim Blinn approach and will work in academic
environments where everything is done by the book. It has the shortcoming
of assuming that input PNG data with no gamma information is linear - this
-is unlikely to be correct unless the PNG files where generated locally.
+is unlikely to be correct unless the PNG files were generated locally.
Most of the time the output precision will be so low as to show
significant banding in dark areas of the image.
@@ -1453,7 +1463,7 @@ png_set_rgb_to_gray()). the single transparent color for
non-paletted images (PNG_INFO_tRNS)
- png_get_eXIf(png_ptr, info_ptr, &exif);
+ png_get_eXIf_1(png_ptr, info_ptr, &num_exif, &exif);
(PNG_INFO_eXIf)
exif - Exif profile (array of png_byte)
@@ -3103,9 +3113,9 @@ width, height, bit_depth, and color_type must be the same in each call. single transparent color for
non-paletted images (PNG_INFO_tRNS)
- png_set_eXIf(png_ptr, info_ptr, exif);
+ png_set_eXIf_1(png_ptr, info_ptr, num_exif, exif);
- hist - Exif profile (array of
+ exif - Exif profile (array of
png_byte) (PNG_INFO_eXIf)
png_set_hIST(png_ptr, info_ptr, hist);
@@ -5404,7 +5414,7 @@ Since the PNG Development group is an ad-hoc body, we can't make an official declaration.
This is your unofficial assurance that libpng from version 0.71 and
-upward through 1.6.31 are Y2K compliant. It is my belief that earlier
+upward through 1.6.34 are Y2K compliant. It is my belief that earlier
versions were also Y2K compliant.
Libpng only has two year fields. One is a 2-byte unsigned integer
diff --git a/plugins/AdvaImg/src/LibPNG/libpng.3 b/plugins/AdvaImg/src/LibPNG/libpng.3 deleted file mode 100644 index c2aae81db7..0000000000 --- a/plugins/AdvaImg/src/LibPNG/libpng.3 +++ /dev/null @@ -1,6235 +0,0 @@ -.TH LIBPNG 3 "July 27, 2017"
-.SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.31
-.SH SYNOPSIS
-\fB
-#include <png.h>\fP
-
-\fBpng_uint_32 png_access_version_number \fI(void\fP\fB);\fP
-
-\fBvoid png_benign_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
-
-\fBvoid png_build_grayscale_palette (int \fP\fIbit_depth\fP\fB, png_colorp \fIpalette\fP\fB);\fP
-
-\fBpng_voidp png_calloc (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
-
-\fBvoid png_chunk_benign_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
-
-\fBvoid png_chunk_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
-
-\fBvoid png_chunk_warning (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fImessage\fP\fB);\fP
-
-\fBvoid png_convert_from_struct_tm (png_timep \fP\fIptime\fP\fB, struct tm FAR * \fIttime\fP\fB);\fP
-
-\fBvoid png_convert_from_time_t (png_timep \fP\fIptime\fP\fB, time_t \fIttime\fP\fB);\fP
-
-\fBpng_charp png_convert_to_rfc1123 (png_structp \fP\fIpng_ptr\fP\fB, png_timep \fIptime\fP\fB);\fP
-
-\fBpng_infop png_create_info_struct (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBpng_structp png_create_read_struct (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarn_fn\fP\fB);\fP
-
-\fBpng_structp png_create_read_struct_2 (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fP\fIwarn_fn\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP
-
-\fBpng_structp png_create_write_struct (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarn_fn\fP\fB);\fP
-
-\fBpng_structp png_create_write_struct_2 (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fP\fIwarn_fn\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP
-
-\fBvoid png_data_freer (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIfreer\fP\fB, png_uint_32 \fImask)\fP\fB);\fP
-
-\fBvoid png_destroy_info_struct (png_structp \fP\fIpng_ptr\fP\fB, png_infopp \fIinfo_ptr_ptr\fP\fB);\fP
-
-\fBvoid png_destroy_read_struct (png_structpp \fP\fIpng_ptr_ptr\fP\fB, png_infopp \fP\fIinfo_ptr_ptr\fP\fB, png_infopp \fIend_info_ptr_ptr\fP\fB);\fP
-
-\fBvoid png_destroy_write_struct (png_structpp \fP\fIpng_ptr_ptr\fP\fB, png_infopp \fIinfo_ptr_ptr\fP\fB);\fP
-
-\fBvoid png_err (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
-
-\fBvoid png_free (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP
-
-\fBvoid png_free_chunk_list (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_free_default (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP
-
-\fBvoid png_free_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fInum\fP\fB);\fP
-
-\fBpng_byte png_get_bit_depth (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBpng_uint_32 png_get_bKGD (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fI*background\fP\fB);\fP
-
-\fBpng_byte png_get_channels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBpng_uint_32 png_get_cHRM (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, double \fP\fI*white_x\fP\fB, double \fP\fI*white_y\fP\fB, double \fP\fI*red_x\fP\fB, double \fP\fI*red_y\fP\fB, double \fP\fI*green_x\fP\fB, double \fP\fI*green_y\fP\fB, double \fP\fI*blue_x\fP\fB, double \fI*blue_y\fP\fB);\fP
-
-\fBpng_uint_32 png_get_cHRM_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*white_x\fP\fB, png_uint_32 \fP\fI*white_y\fP\fB, png_uint_32 \fP\fI*red_x\fP\fB, png_uint_32 \fP\fI*red_y\fP\fB, png_uint_32 \fP\fI*green_x\fP\fB, png_uint_32 \fP\fI*green_y\fP\fB, png_uint_32 \fP\fI*blue_x\fP\fB, png_uint_32 \fI*blue_y\fP\fB);\fP
-
-\fBpng_uint_32 png_get_cHRM_XYZ (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, double \fP\fI*red_X\fP\fB, double \fP\fI*red_Y\fP\fB, double \fP\fI*red_Z\fP\fB, double \fP\fI*green_X\fP\fB, double \fP\fI*green_Y\fP\fB, double \fP\fI*green_Z\fP\fB, double \fP\fI*blue_X\fP\fB, double \fP\fI*blue_Y\fP\fB, double \fI*blue_Z\fP\fB);\fP
-
-\fBpng_uint_32 png_get_cHRM_XYZ_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_fixed_point \fP\fI*int_red_X\fP\fB, png_fixed_point \fP\fI*int_red_Y\fP\fB, png_fixed_point \fP\fI*int_red_Z\fP\fB, png_fixed_point \fP\fI*int_green_X\fP\fB, png_fixed_point \fP\fI*int_green_Y\fP\fB, png_fixed_point \fP\fI*int_green_Z\fP\fB, png_fixed_point \fP\fI*int_blue_X\fP\fB, png_fixed_point \fP\fI*int_blue_Y\fP\fB, png_fixed_point \fI*int_blue_Z\fP\fB);\fP
-
-\fBpng_uint_32 png_get_chunk_cache_max (png_const_structp \fIpng_ptr\fP\fB);\fP
-
-\fBpng_alloc_size_t png_get_chunk_malloc_max (png_const_structp \fIpng_ptr\fP\fB);\fP
-
-\fBpng_byte png_get_color_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBpng_uint_32 png_get_compression_buffer_size (png_const_structp \fIpng_ptr\fP\fB);\fP
-
-\fBpng_byte png_get_compression_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBpng_byte png_get_copyright (png_const_structp \fIpng_ptr\fP\fB);\fP
-
-\fBpng_uint_32 png_get_current_row_number \fI(png_const_structp\fP\fB);\fP
-
-\fBpng_byte png_get_current_pass_number \fI(png_const_structp\fP\fB);\fP
-
-\fBpng_voidp png_get_error_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
-
-\fBpng_byte png_get_filter_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBpng_uint_32 png_get_gAMA (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, double \fI*file_gamma\fP\fB);\fP
-
-\fBpng_uint_32 png_get_gAMA_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fI*int_file_gamma\fP\fB);\fP
-
-\fBpng_byte png_get_header_ver (png_const_structp \fIpng_ptr\fP\fB);\fP
-
-\fBpng_byte png_get_header_version (png_const_structp \fIpng_ptr\fP\fB);\fP
-
-\fBpng_uint_32 png_get_eXIf (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fI*exif\fP\fB);\fP
-
-\fBpng_uint_32 png_get_hIST (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fI*hist\fP\fB);\fP
-
-\fBpng_uint_32 png_get_iCCP (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_charpp \fP\fIname\fP\fB, int \fP\fI*compression_type\fP\fB, png_bytepp \fP\fIprofile\fP\fB, png_uint_32 \fI*proflen\fP\fB);\fP
-
-\fBpng_uint_32 png_get_IHDR (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*width\fP\fB, png_uint_32 \fP\fI*height\fP\fB, int \fP\fI*bit_depth\fP\fB, int \fP\fI*color_type\fP\fB, int \fP\fI*interlace_type\fP\fB, int \fP\fI*compression_type\fP\fB, int \fI*filter_type\fP\fB);\fP
-
-\fBpng_uint_32 png_get_image_height (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBpng_uint_32 png_get_image_width (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBpng_int_32 png_get_int_32 (png_bytep \fIbuf\fP\fB);\fP
-
-\fBpng_byte png_get_interlace_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBpng_uint_32 png_get_io_chunk_type (png_const_structp \fIpng_ptr\fP\fB);\fP
-
-\fBpng_voidp png_get_io_ptr (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBpng_uint_32 png_get_io_state (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBpng_byte png_get_libpng_ver (png_const_structp \fIpng_ptr\fP\fB);\fP
-
-\fBint png_get_palette_max(png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBpng_voidp png_get_mem_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
-
-\fBpng_uint_32 png_get_oFFs (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*offset_x\fP\fB, png_uint_32 \fP\fI*offset_y\fP\fB, int \fI*unit_type\fP\fB);\fP
-
-\fBpng_uint_32 png_get_pCAL (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fI*purpose\fP\fB, png_int_32 \fP\fI*X0\fP\fB, png_int_32 \fP\fI*X1\fP\fB, int \fP\fI*type\fP\fB, int \fP\fI*nparams\fP\fB, png_charp \fP\fI*units\fP\fB, png_charpp \fI*params\fP\fB);\fP
-
-\fBpng_uint_32 png_get_pHYs (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*res_x\fP\fB, png_uint_32 \fP\fI*res_y\fP\fB, int \fI*unit_type\fP\fB);\fP
-
-\fBfloat png_get_pixel_aspect_ratio (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBpng_uint_32 png_get_pHYs_dpi (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*res_x\fP\fB, png_uint_32 \fP\fI*res_y\fP\fB, int \fI*unit_type\fP\fB);\fP
-
-\fBpng_fixed_point png_get_pixel_aspect_ratio_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBpng_uint_32 png_get_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBpng_uint_32 png_get_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBpng_voidp png_get_progressive_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
-
-\fBpng_uint_32 png_get_PLTE (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_colorp \fP\fI*palette\fP\fB, int \fI*num_palette\fP\fB);\fP
-
-\fBpng_byte png_get_rgb_to_gray_status (png_const_structp \fIpng_ptr\fP\fB);\fP
-
-\fBpng_uint_32 png_get_rowbytes (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBpng_bytepp png_get_rows (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBpng_uint_32 png_get_sBIT (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_8p \fI*sig_bit\fP\fB);\fP
-
-\fBvoid png_get_sCAL (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, double* \fP\fIwidth\fP\fB, double* \fIheight\fP\fB);\fP
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-\fBvoid png_get_sCAL_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, png_fixed_pointp \fP\fIwidth\fP\fB, png_fixed_pointp \fIheight\fP\fB);\fP
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-\fBvoid png_get_sCAL_s (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, png_charpp \fP\fIwidth\fP\fB, png_charpp \fIheight\fP\fB);\fP
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-\fBpng_bytep png_get_signature (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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-\fBpng_uint_32 png_get_sPLT (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_spalette_p \fI*splt_ptr\fP\fB);\fP
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-\fBpng_uint_32 png_get_sRGB (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int \fI*file_srgb_intent\fP\fB);\fP
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-\fBpng_uint_32 png_get_text (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_textp \fP\fI*text_ptr\fP\fB, int \fI*num_text\fP\fB);\fP
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-\fBpng_uint_32 png_get_tIME (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_timep \fI*mod_time\fP\fB);\fP
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-\fBpng_uint_32 png_get_tRNS (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fI*trans_alpha\fP\fB, int \fP\fI*num_trans\fP\fB, png_color_16p \fI*trans_color\fP\fB);\fP
-
-\fB/* This function is really an inline macro. \fI*/
-
-\fBpng_uint_16 png_get_uint_16 (png_bytep \fIbuf\fP\fB);\fP
-
-\fBpng_uint_32 png_get_uint_31 (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIbuf\fP\fB);\fP
-
-\fB/* This function is really an inline macro. \fI*/
-
-\fBpng_uint_32 png_get_uint_32 (png_bytep \fIbuf\fP\fB);\fP
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-\fBpng_uint_32 png_get_unknown_chunks (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_unknown_chunkpp \fIunknowns\fP\fB);\fP
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-\fBpng_voidp png_get_user_chunk_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
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-\fBpng_uint_32 png_get_user_height_max (png_const_structp \fIpng_ptr\fP\fB);\fP
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-\fBpng_voidp png_get_user_transform_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
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-\fBpng_uint_32 png_get_user_width_max (png_const_structp \fIpng_ptr\fP\fB);\fP
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-\fBpng_uint_32 png_get_valid (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIflag\fP\fB);\fP
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-\fBfloat png_get_x_offset_inches (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
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-\fBpng_fixed_point png_get_x_offset_inches_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
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-\fBpng_int_32 png_get_x_offset_microns (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
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-\fBpng_int_32 png_get_x_offset_pixels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
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-\fBpng_uint_32 png_get_x_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
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-\fBpng_uint_32 png_get_x_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
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-\fBfloat png_get_y_offset_inches (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
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-\fBpng_fixed_point png_get_y_offset_inches_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
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-\fBpng_int_32 png_get_y_offset_microns (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
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-\fBpng_int_32 png_get_y_offset_pixels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
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-\fBpng_uint_32 png_get_y_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
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-\fBpng_uint_32 png_get_y_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
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-\fBint png_handle_as_unknown (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIchunk_name\fP\fB);\fP
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-\fBint png_image_begin_read_from_file (png_imagep \fP\fIimage\fP\fB, const char \fI*file_name\fP\fB);\fP
-
-\fBint png_image_begin_read_from_stdio (png_imagep \fP\fIimage\fP\fB, FILE* \fIfile\fP\fB);\fP
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-\fBint, png_image_begin_read_from_memory (png_imagep \fP\fIimage\fP\fB, png_const_voidp \fP\fImemory\fP\fB, png_size_t \fIsize\fP\fB);\fP
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-\fBint png_image_finish_read (png_imagep \fP\fIimage\fP\fB, png_colorp \fP\fIbackground\fP\fB, void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, void \fI*colormap\fP\fB);\fP
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-\fBvoid png_image_free (png_imagep \fIimage\fP\fB);\fP
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-\fBint png_image_write_to_file (png_imagep \fP\fIimage\fP\fB, const char \fP\fI*file\fP\fB, int \fP\fIconvert_to_8bit\fP\fB, const void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, void \fI*colormap\fP\fB);\fP
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-\fBint png_image_write_to_memory (png_imagep \fP\fIimage\fP\fB, void \fP\fI*memory\fP\fB, png_alloc_size_t * PNG_RESTRICT \fP\fImemory_bytes\fP\fB, int \fP\fIconvert_to_8_bit\fP\fB, const void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, const void \fI*colormap)\fP\fB);\fP
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-\fBint png_image_write_to_stdio (png_imagep \fP\fIimage\fP\fB, FILE \fP\fI*file\fP\fB, int \fP\fIconvert_to_8_bit\fP\fB, const void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, void \fI*colormap)\fP\fB);\fP
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-\fBvoid png_info_init_3 (png_infopp \fP\fIinfo_ptr\fP\fB, png_size_t \fIpng_info_struct_size\fP\fB);\fP
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-\fBvoid png_init_io (png_structp \fP\fIpng_ptr\fP\fB, FILE \fI*fp\fP\fB);\fP
-
-\fBvoid png_longjmp (png_structp \fP\fIpng_ptr\fP\fB, int \fIval\fP\fB);\fP
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-\fBpng_voidp png_malloc (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
-
-\fBpng_voidp png_malloc_default (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
-
-\fBpng_voidp png_malloc_warn (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
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-\fBpng_uint_32 png_permit_mng_features (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fImng_features_permitted\fP\fB);\fP
-
-\fBvoid png_process_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fIbuffer\fP\fB, png_size_t \fIbuffer_size\fP\fB);\fP
-
-\fBpng_size_t png_process_data_pause \fP\fI(png_structp\fP\fB, int \fIsave\fP\fB);\fP
-
-\fBpng_uint_32 png_process_data_skip \fI(png_structp\fP\fB);\fP
-
-\fBvoid png_progressive_combine_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIold_row\fP\fB, png_bytep \fInew_row\fP\fB);\fP
-
-\fBvoid png_read_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBvoid png_read_image (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fIimage\fP\fB);\fP
-
-\fBvoid png_read_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBvoid png_read_png (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fItransforms\fP\fB, png_voidp \fIparams\fP\fB);\fP
-
-\fBvoid png_read_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIrow\fP\fB, png_bytep \fIdisplay_row\fP\fB);\fP
-
-\fBvoid png_read_rows (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fP\fIrow\fP\fB, png_bytepp \fP\fIdisplay_row\fP\fB, png_uint_32 \fInum_rows\fP\fB);\fP
-
-\fBvoid png_read_update_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBint png_reset_zstream (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_save_int_32 (png_bytep \fP\fIbuf\fP\fB, png_int_32 \fIi\fP\fB);\fP
-
-\fBvoid png_save_uint_16 (png_bytep \fP\fIbuf\fP\fB, unsigned int \fIi\fP\fB);\fP
-
-\fBvoid png_save_uint_32 (png_bytep \fP\fIbuf\fP\fB, png_uint_32 \fIi\fP\fB);\fP
-
-\fBvoid png_set_add_alpha (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIfiller\fP\fB, int \fIflags\fP\fB);\fP
-
-\fBvoid png_set_alpha_mode (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImode\fP\fB, double \fIoutput_gamma\fP\fB);\fP
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-\fBvoid png_set_alpha_mode_fixed (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImode\fP\fB, png_fixed_point \fIoutput_gamma\fP\fB);\fP
-
-\fBvoid png_set_background (png_structp \fP\fIpng_ptr\fP\fB, png_color_16p \fP\fIbackground_color\fP\fB, int \fP\fIbackground_gamma_code\fP\fB, int \fP\fIneed_expand\fP\fB, double \fIbackground_gamma\fP\fB);\fP
-
-\fBvoid png_set_background_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_color_16p \fP\fIbackground_color\fP\fB, int \fP\fIbackground_gamma_code\fP\fB, int \fP\fIneed_expand\fP\fB, png_uint_32 \fIbackground_gamma\fP\fB);\fP
-
-\fBvoid png_set_benign_errors (png_structp \fP\fIpng_ptr\fP\fB, int \fIallowed\fP\fB);\fP
-
-\fBvoid png_set_bgr (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_set_bKGD (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fIbackground\fP\fB);\fP
-
-\fBvoid png_set_check_for_invalid_index(png_structrp \fP\fIpng_ptr\fP\fB, int \fIallowed\fP\fB);\fP
-
-\fBvoid png_set_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fP\fIwhite_x\fP\fB, double \fP\fIwhite_y\fP\fB, double \fP\fIred_x\fP\fB, double \fP\fIred_y\fP\fB, double \fP\fIgreen_x\fP\fB, double \fP\fIgreen_y\fP\fB, double \fP\fIblue_x\fP\fB, double \fIblue_y\fP\fB);\fP
-
-\fBvoid png_set_cHRM_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIwhite_x\fP\fB, png_uint_32 \fP\fIwhite_y\fP\fB, png_uint_32 \fP\fIred_x\fP\fB, png_uint_32 \fP\fIred_y\fP\fB, png_uint_32 \fP\fIgreen_x\fP\fB, png_uint_32 \fP\fIgreen_y\fP\fB, png_uint_32 \fP\fIblue_x\fP\fB, png_uint_32 \fIblue_y\fP\fB);\fP
-
-\fBvoid png_set_cHRM_XYZ (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fP\fIred_X\fP\fB, double \fP\fIred_Y\fP\fB, double \fP\fIred_Z\fP\fB, double \fP\fIgreen_X\fP\fB, double \fP\fIgreen_Y\fP\fB, double \fP\fIgreen_Z\fP\fB, double \fP\fIblue_X\fP\fB, double \fP\fIblue_Y\fP\fB, double \fIblue_Z\fP\fB);\fP
-
-\fBvoid png_set_cHRM_XYZ_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_fixed_point \fP\fIint_red_X\fP\fB, png_fixed_point \fP\fIint_red_Y\fP\fB, png_fixed_point \fP\fIint_red_Z\fP\fB, png_fixed_point \fP\fIint_green_X\fP\fB, png_fixed_point \fP\fIint_green_Y\fP\fB, png_fixed_point \fP\fIint_green_Z\fP\fB, png_fixed_point \fP\fIint_blue_X\fP\fB, png_fixed_point \fP\fIint_blue_Y\fP\fB, png_fixed_point \fIint_blue_Z\fP\fB);\fP
-
-\fBvoid png_set_chunk_cache_max (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIuser_chunk_cache_max\fP\fB);\fP
-
-\fBvoid png_set_compression_level (png_structp \fP\fIpng_ptr\fP\fB, int \fIlevel\fP\fB);\fP
-
-\fBvoid png_set_compression_mem_level (png_structp \fP\fIpng_ptr\fP\fB, int \fImem_level\fP\fB);\fP
-
-\fBvoid png_set_compression_method (png_structp \fP\fIpng_ptr\fP\fB, int \fImethod\fP\fB);\fP
-
-\fBvoid png_set_compression_strategy (png_structp \fP\fIpng_ptr\fP\fB, int \fIstrategy\fP\fB);\fP
-
-\fBvoid png_set_compression_window_bits (png_structp \fP\fIpng_ptr\fP\fB, int \fIwindow_bits\fP\fB);\fP
-
-\fBvoid png_set_crc_action (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIcrit_action\fP\fB, int \fIancil_action\fP\fB);\fP
-
-\fBvoid png_set_error_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarning_fn\fP\fB);\fP
-
-\fBvoid png_set_expand (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_set_expand_16 (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_set_expand_gray_1_2_4_to_8 (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_set_filler (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIfiller\fP\fB, int \fIflags\fP\fB);\fP
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-\fBvoid png_set_filter (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImethod\fP\fB, int \fIfilters\fP\fB);\fP
-
-\fBvoid png_set_filter_heuristics (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIheuristic_method\fP\fB, int \fP\fInum_weights\fP\fB, png_doublep \fP\fIfilter_weights\fP\fB, png_doublep \fIfilter_costs\fP\fB);\fP
-
-\fBvoid png_set_filter_heuristics_fixed (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIheuristic_method\fP\fB, int \fP\fInum_weights\fP\fB, png_fixed_point_p \fP\fIfilter_weights\fP\fB, png_fixed_point_p \fIfilter_costs\fP\fB);\fP
-
-\fBvoid png_set_flush (png_structp \fP\fIpng_ptr\fP\fB, int \fInrows\fP\fB);\fP
-
-\fBvoid png_set_gamma (png_structp \fP\fIpng_ptr\fP\fB, double \fP\fIscreen_gamma\fP\fB, double \fIdefault_file_gamma\fP\fB);\fP
-
-\fBvoid png_set_gamma_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIscreen_gamma\fP\fB, png_uint_32 \fIdefault_file_gamma\fP\fB);\fP
-
-\fBvoid png_set_gAMA (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fIfile_gamma\fP\fB);\fP
-
-\fBvoid png_set_gAMA_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIfile_gamma\fP\fB);\fP
-
-\fBvoid png_set_gray_1_2_4_to_8 (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_set_gray_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_set_eXIf (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fIexif\fP\fB);\fP
-
-\fBvoid png_set_hIST (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fIhist\fP\fB);\fP
-
-\fBvoid png_set_iCCP (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_const_charp \fP\fIname\fP\fB, int \fP\fIcompression_type\fP\fB, png_const_bytep \fP\fIprofile\fP\fB, png_uint_32 \fIproflen\fP\fB);\fP
-
-\fBint png_set_interlace_handling (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_set_invalid (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fImask\fP\fB);\fP
-
-\fBvoid png_set_invert_alpha (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_set_invert_mono (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_set_IHDR (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIwidth\fP\fB, png_uint_32 \fP\fIheight\fP\fB, int \fP\fIbit_depth\fP\fB, int \fP\fIcolor_type\fP\fB, int \fP\fIinterlace_type\fP\fB, int \fP\fIcompression_type\fP\fB, int \fIfilter_type\fP\fB);\fP
-
-\fBvoid png_set_keep_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIkeep\fP\fB, png_bytep \fP\fIchunk_list\fP\fB, int \fInum_chunks\fP\fB);\fP
-
-\fBjmp_buf* png_set_longjmp_fn (png_structp \fP\fIpng_ptr\fP\fB, png_longjmp_ptr \fP\fIlongjmp_fn\fP\fB, size_t \fIjmp_buf_size\fP\fB);\fP
-
-\fBvoid png_set_chunk_malloc_max (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIuser_chunk_cache_max\fP\fB);\fP
-
-\fBvoid png_set_compression_buffer_size (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIsize\fP\fB);\fP
-
-\fBvoid png_set_mem_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP
-
-\fBvoid png_set_oFFs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIoffset_x\fP\fB, png_uint_32 \fP\fIoffset_y\fP\fB, int \fIunit_type\fP\fB);\fP
-
-\fBint png_set_option(png_structrp \fP\fIpng_ptr\fP\fB, int \fP\fIoption\fP\fB, int \fIonoff\fP\fB);\fP
-
-\fBvoid png_set_packing (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_set_packswap (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_set_palette_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_set_pCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fIpurpose\fP\fB, png_int_32 \fP\fIX0\fP\fB, png_int_32 \fP\fIX1\fP\fB, int \fP\fItype\fP\fB, int \fP\fInparams\fP\fB, png_charp \fP\fIunits\fP\fB, png_charpp \fIparams\fP\fB);\fP
-
-\fBvoid png_set_pHYs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIres_x\fP\fB, png_uint_32 \fP\fIres_y\fP\fB, int \fIunit_type\fP\fB);\fP
-
-\fBvoid png_set_progressive_read_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIprogressive_ptr\fP\fB, png_progressive_info_ptr \fP\fIinfo_fn\fP\fB, png_progressive_row_ptr \fP\fIrow_fn\fP\fB, png_progressive_end_ptr \fIend_fn\fP\fB);\fP
-
-\fBvoid png_set_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fInum_palette\fP\fB);\fP
-
-\fBvoid png_set_quantize (png_structp \fP\fIpng_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fP\fInum_palette\fP\fB, int \fP\fImaximum_colors\fP\fB, png_uint_16p \fP\fIhistogram\fP\fB, int \fIfull_quantize\fP\fB);\fP
-
-\fBvoid png_set_read_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIio_ptr\fP\fB, png_rw_ptr \fIread_data_fn\fP\fB);\fP
-
-\fBvoid png_set_read_status_fn (png_structp \fP\fIpng_ptr\fP\fB, png_read_status_ptr \fIread_row_fn\fP\fB);\fP
-
-\fBvoid png_set_read_user_chunk_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIuser_chunk_ptr\fP\fB, png_user_chunk_ptr \fIread_user_chunk_fn\fP\fB);\fP
-
-\fBvoid png_set_read_user_transform_fn (png_structp \fP\fIpng_ptr\fP\fB, png_user_transform_ptr \fIread_user_transform_fn\fP\fB);\fP
-
-\fBvoid png_set_rgb_to_gray (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIerror_action\fP\fB, double \fP\fIred\fP\fB, double \fIgreen\fP\fB);\fP
-
-\fBvoid png_set_rgb_to_gray_fixed (png_structp \fP\fIpng_ptr\fP\fB, int error_action png_uint_32 \fP\fIred\fP\fB, png_uint_32 \fIgreen\fP\fB);\fP
-
-\fBvoid png_set_rows (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytepp \fIrow_pointers\fP\fB);\fP
-
-\fBvoid png_set_sBIT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_8p \fIsig_bit\fP\fB);\fP
-
-\fBvoid png_set_sCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, double \fP\fIwidth\fP\fB, double \fIheight\fP\fB);\fP
-
-\fBvoid png_set_sCAL_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, png_fixed_point \fP\fIwidth\fP\fB, png_fixed_point \fIheight\fP\fB);\fP
-
-\fBvoid png_set_sCAL_s (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, png_charp \fP\fIwidth\fP\fB, png_charp \fIheight\fP\fB);\fP
-
-\fBvoid png_set_scale_16 (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_set_shift (png_structp \fP\fIpng_ptr\fP\fB, png_color_8p \fItrue_bits\fP\fB);\fP
-
-\fBvoid png_set_sig_bytes (png_structp \fP\fIpng_ptr\fP\fB, int \fInum_bytes\fP\fB);\fP
-
-\fBvoid png_set_sPLT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_spalette_p \fP\fIsplt_ptr\fP\fB, int \fInum_spalettes\fP\fB);\fP
-
-\fBvoid png_set_sRGB (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fIsrgb_intent\fP\fB);\fP
-
-\fBvoid png_set_sRGB_gAMA_and_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fIsrgb_intent\fP\fB);\fP
-
-\fBvoid png_set_strip_16 (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_set_strip_alpha (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_set_strip_error_numbers (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIstrip_mode\fP\fB);\fP
-
-\fBvoid png_set_swap (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_set_swap_alpha (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_set_text (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_textp \fP\fItext_ptr\fP\fB, int \fInum_text\fP\fB);\fP
-
-\fBvoid png_set_text_compression_level (png_structp \fP\fIpng_ptr\fP\fB, int \fIlevel\fP\fB);\fP
-
-\fBvoid png_set_text_compression_mem_level (png_structp \fP\fIpng_ptr\fP\fB, int \fImem_level\fP\fB);\fP
-
-\fBvoid png_set_text_compression_strategy (png_structp \fP\fIpng_ptr\fP\fB, int \fIstrategy\fP\fB);\fP
-
-\fBvoid png_set_text_compression_window_bits (png_structp \fP\fIpng_ptr\fP\fB, int \fIwindow_bits\fP\fB);\fP
-
-\fBvoid \fP\fIpng_set_text_compression_method\fP\fB, (png_structp \fP\fIpng_ptr\fP\fB, int \fImethod)\fP\fB);\fP
-
-\fBvoid png_set_tIME (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_timep \fImod_time\fP\fB);\fP
-
-\fBvoid png_set_tRNS (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fItrans_alpha\fP\fB, int \fP\fInum_trans\fP\fB, png_color_16p \fItrans_color\fP\fB);\fP
-
-\fBvoid png_set_tRNS_to_alpha (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBpng_uint_32 png_set_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_unknown_chunkp \fP\fIunknowns\fP\fB, int \fP\fInum\fP\fB, int \fIlocation\fP\fB);\fP
-
-\fBvoid png_set_unknown_chunk_location (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIchunk\fP\fB, int \fIlocation\fP\fB);\fP
-
-\fBvoid png_set_user_limits (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIuser_width_max\fP\fB, png_uint_32 \fIuser_height_max\fP\fB);\fP
-
-\fBvoid png_set_user_transform_info (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIuser_transform_ptr\fP\fB, int \fP\fIuser_transform_depth\fP\fB, int \fIuser_transform_channels\fP\fB);\fP
-
-\fBvoid png_set_write_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIio_ptr\fP\fB, png_rw_ptr \fP\fIwrite_data_fn\fP\fB, png_flush_ptr \fIoutput_flush_fn\fP\fB);\fP
-
-\fBvoid png_set_write_status_fn (png_structp \fP\fIpng_ptr\fP\fB, png_write_status_ptr \fIwrite_row_fn\fP\fB);\fP
-
-\fBvoid png_set_write_user_transform_fn (png_structp \fP\fIpng_ptr\fP\fB, png_user_transform_ptr \fIwrite_user_transform_fn\fP\fB);\fP
-
-\fBint png_sig_cmp (png_bytep \fP\fIsig\fP\fB, png_size_t \fP\fIstart\fP\fB, png_size_t \fInum_to_check\fP\fB);\fP
-
-\fBvoid png_start_read_image (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_warning (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fImessage\fP\fB);\fP
-
-\fBvoid png_write_chunk (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIchunk_name\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP
-
-\fBvoid png_write_chunk_data (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP
-
-\fBvoid png_write_chunk_end (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_write_chunk_start (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIchunk_name\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
-
-\fBvoid png_write_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBvoid png_write_flush (png_structp \fIpng_ptr\fP\fB);\fP
-
-\fBvoid png_write_image (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fIimage\fP\fB);\fP
-
-\fBvoid png_write_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBvoid png_write_info_before_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
-
-\fBvoid png_write_png (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fItransforms\fP\fB, png_voidp \fIparams\fP\fB);\fP
-
-\fBvoid png_write_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIrow\fP\fB);\fP
-
-\fBvoid png_write_rows (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fP\fIrow\fP\fB, png_uint_32 \fInum_rows\fP\fB);\fP
-
-\fBvoid png_write_sig (png_structp \fIpng_ptr\fP\fB);\fP
-
-.SH DESCRIPTION
-The
-.I libpng
-library supports encoding, decoding, and various manipulations of
-the Portable Network Graphics (PNG) format image files. It uses the
-.IR zlib(3)
-compression library.
-Following is a copy of the libpng-manual.txt file that accompanies libpng.
-.SH LIBPNG.TXT
-libpng-manual.txt - A description on how to use and modify libpng
-
- libpng version 1.6.31 - July 27, 2017
- Updated and distributed by Glenn Randers-Pehrson
- <glennrp at users.sourceforge.net>
- Copyright (c) 1998-2017 Glenn Randers-Pehrson
-
- This document is released under the libpng license.
- For conditions of distribution and use, see the disclaimer
- and license in png.h
-
- Based on:
-
- libpng versions 0.97, January 1998, through 1.6.31 - July 27, 2017
- Updated and distributed by Glenn Randers-Pehrson
- Copyright (c) 1998-2017 Glenn Randers-Pehrson
-
- libpng 1.0 beta 6 - version 0.96 - May 28, 1997
- Updated and distributed by Andreas Dilger
- Copyright (c) 1996, 1997 Andreas Dilger
-
- libpng 1.0 beta 2 - version 0.88 - January 26, 1996
- For conditions of distribution and use, see copyright
- notice in png.h. Copyright (c) 1995, 1996 Guy Eric
- Schalnat, Group 42, Inc.
-
- Updated/rewritten per request in the libpng FAQ
- Copyright (c) 1995, 1996 Frank J. T. Wojcik
- December 18, 1995 & January 20, 1996
-
- TABLE OF CONTENTS
-
- I. Introduction
- II. Structures
- III. Reading
- IV. Writing
- V. Simplified API
- VI. Modifying/Customizing libpng
- VII. MNG support
- VIII. Changes to Libpng from version 0.88
- IX. Changes to Libpng from version 1.0.x to 1.2.x
- X. Changes to Libpng from version 1.0.x/1.2.x to 1.4.x
- XI. Changes to Libpng from version 1.4.x to 1.5.x
- XII. Changes to Libpng from version 1.5.x to 1.6.x
- XIII. Detecting libpng
- XIV. Source code repository
- XV. Coding style
- XVI. Y2K Compliance in libpng
-
-.SH I. Introduction
-
-This file describes how to use and modify the PNG reference library
-(known as libpng) for your own use. In addition to this
-file, example.c is a good starting point for using the library, as
-it is heavily commented and should include everything most people
-will need. We assume that libpng is already installed; see the
-INSTALL file for instructions on how to configure and install libpng.
-
-For examples of libpng usage, see the files "example.c", "pngtest.c",
-and the files in the "contrib" directory, all of which are included in
-the libpng distribution.
-
-Libpng was written as a companion to the PNG specification, as a way
-of reducing the amount of time and effort it takes to support the PNG
-file format in application programs.
-
-The PNG specification (second edition), November 2003, is available as
-a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2004 (E)) at
-<https://www.w3.org/TR/2003/REC-PNG-20031110/
-The W3C and ISO documents have identical technical content.
-
-The PNG-1.2 specification is available at
-<https://png-mng.sourceforge.io/pub/png/spec/1.2/>.
-It is technically equivalent
-to the PNG specification (second edition) but has some additional material.
-
-The PNG-1.0 specification is available as RFC 2083
-<https://png-mng.sourceforge.io/pub/png/spec/1.0/> and as a
-W3C Recommendation <https://www.w3.org/TR/REC-png-961001>.
-
-Some additional chunks are described in the special-purpose public chunks
-documents at <http://www.libpng.org/pub/png/spec/register/>
-
-Other information
-about PNG, and the latest version of libpng, can be found at the PNG home
-page, <http://www.libpng.org/pub/png/>.
-
-Most users will not have to modify the library significantly; advanced
-users may want to modify it more. All attempts were made to make it as
-complete as possible, while keeping the code easy to understand.
-Currently, this library only supports C. Support for other languages
-is being considered.
-
-Libpng has been designed to handle multiple sessions at one time,
-to be easily modifiable, to be portable to the vast majority of
-machines (ANSI, K&R, 16-, 32-, and 64-bit) available, and to be easy
-to use. The ultimate goal of libpng is to promote the acceptance of
-the PNG file format in whatever way possible. While there is still
-work to be done (see the TODO file), libpng should cover the
-majority of the needs of its users.
-
-Libpng uses zlib for its compression and decompression of PNG files.
-Further information about zlib, and the latest version of zlib, can
-be found at the zlib home page, <https://zlib.net/>.
-The zlib compression utility is a general purpose utility that is
-useful for more than PNG files, and can be used without libpng.
-See the documentation delivered with zlib for more details.
-You can usually find the source files for the zlib utility wherever you
-find the libpng source files.
-
-Libpng is thread safe, provided the threads are using different
-instances of the structures. Each thread should have its own
-png_struct and png_info instances, and thus its own image.
-Libpng does not protect itself against two threads using the
-same instance of a structure.
-
-.SH II. Structures
-
-There are two main structures that are important to libpng, png_struct
-and png_info. Both are internal structures that are no longer exposed
-in the libpng interface (as of libpng 1.5.0).
-
-The png_info structure is designed to provide information about the
-PNG file. At one time, the fields of png_info were intended to be
-directly accessible to the user. However, this tended to cause problems
-with applications using dynamically loaded libraries, and as a result
-a set of interface functions for png_info (the png_get_*() and png_set_*()
-functions) was developed, and direct access to the png_info fields was
-deprecated..
-
-The png_struct structure is the object used by the library to decode a
-single image. As of 1.5.0 this structure is also not exposed.
-
-Almost all libpng APIs require a pointer to a png_struct as the first argument.
-Many (in particular the png_set and png_get APIs) also require a pointer
-to png_info as the second argument. Some application visible macros
-defined in png.h designed for basic data access (reading and writing
-integers in the PNG format) don't take a png_info pointer, but it's almost
-always safe to assume that a (png_struct*) has to be passed to call an API
-function.
-
-You can have more than one png_info structure associated with an image,
-as illustrated in pngtest.c, one for information valid prior to the
-IDAT chunks and another (called "end_info" below) for things after them.
-
-The png.h header file is an invaluable reference for programming with libpng.
-And while I'm on the topic, make sure you include the libpng header file:
-
-#include <png.h>
-
-and also (as of libpng-1.5.0) the zlib header file, if you need it:
-
-#include <zlib.h>
-
-.SS Types
-
-The png.h header file defines a number of integral types used by the
-APIs. Most of these are fairly obvious; for example types corresponding
-to integers of particular sizes and types for passing color values.
-
-One exception is how non-integral numbers are handled. For application
-convenience most APIs that take such numbers have C (double) arguments;
-however, internally PNG, and libpng, use 32 bit signed integers and encode
-the value by multiplying by 100,000. As of libpng 1.5.0 a convenience
-macro PNG_FP_1 is defined in png.h along with a type (png_fixed_point)
-which is simply (png_int_32).
-
-All APIs that take (double) arguments also have a matching API that
-takes the corresponding fixed point integer arguments. The fixed point
-API has the same name as the floating point one with "_fixed" appended.
-The actual range of values permitted in the APIs is frequently less than
-the full range of (png_fixed_point) (\-21474 to +21474). When APIs require
-a non-negative argument the type is recorded as png_uint_32 above. Consult
-the header file and the text below for more information.
-
-Special care must be take with sCAL chunk handling because the chunk itself
-uses non-integral values encoded as strings containing decimal floating point
-numbers. See the comments in the header file.
-
-.SS Configuration
-
-The main header file function declarations are frequently protected by C
-preprocessing directives of the form:
-
- #ifdef PNG_feature_SUPPORTED
- declare-function
- #endif
- ...
- #ifdef PNG_feature_SUPPORTED
- use-function
- #endif
-
-The library can be built without support for these APIs, although a
-standard build will have all implemented APIs. Application programs
-should check the feature macros before using an API for maximum
-portability. From libpng 1.5.0 the feature macros set during the build
-of libpng are recorded in the header file "pnglibconf.h" and this file
-is always included by png.h.
-
-If you don't need to change the library configuration from the default, skip to
-the next section ("Reading").
-
-Notice that some of the makefiles in the 'scripts' directory and (in 1.5.0) all
-of the build project files in the 'projects' directory simply copy
-scripts/pnglibconf.h.prebuilt to pnglibconf.h. This means that these build
-systems do not permit easy auto-configuration of the library - they only
-support the default configuration.
-
-The easiest way to make minor changes to the libpng configuration when
-auto-configuration is supported is to add definitions to the command line
-using (typically) CPPFLAGS. For example:
-
-CPPFLAGS=\-DPNG_NO_FLOATING_ARITHMETIC
-
-will change the internal libpng math implementation for gamma correction and
-other arithmetic calculations to fixed point, avoiding the need for fast
-floating point support. The result can be seen in the generated pnglibconf.h -
-make sure it contains the changed feature macro setting.
-
-If you need to make more extensive configuration changes - more than one or two
-feature macro settings - you can either add \-DPNG_USER_CONFIG to the build
-command line and put a list of feature macro settings in pngusr.h or you can set
-DFA_XTRA (a makefile variable) to a file containing the same information in the
-form of 'option' settings.
-
-A. Changing pnglibconf.h
-
-A variety of methods exist to build libpng. Not all of these support
-reconfiguration of pnglibconf.h. To reconfigure pnglibconf.h it must either be
-rebuilt from scripts/pnglibconf.dfa using awk or it must be edited by hand.
-
-Hand editing is achieved by copying scripts/pnglibconf.h.prebuilt to
-pnglibconf.h and changing the lines defining the supported features, paying
-very close attention to the 'option' information in scripts/pnglibconf.dfa
-that describes those features and their requirements. This is easy to get
-wrong.
-
-B. Configuration using DFA_XTRA
-
-Rebuilding from pnglibconf.dfa is easy if a functioning 'awk', or a later
-variant such as 'nawk' or 'gawk', is available. The configure build will
-automatically find an appropriate awk and build pnglibconf.h.
-The scripts/pnglibconf.mak file contains a set of make rules for doing the
-same thing if configure is not used, and many of the makefiles in the scripts
-directory use this approach.
-
-When rebuilding simply write a new file containing changed options and set
-DFA_XTRA to the name of this file. This causes the build to append the new file
-to the end of scripts/pnglibconf.dfa. The pngusr.dfa file should contain lines
-of the following forms:
-
-everything = off
-
-This turns all optional features off. Include it at the start of pngusr.dfa to
-make it easier to build a minimal configuration. You will need to turn at least
-some features on afterward to enable either reading or writing code, or both.
-
-option feature on
-option feature off
-
-Enable or disable a single feature. This will automatically enable other
-features required by a feature that is turned on or disable other features that
-require a feature which is turned off. Conflicting settings will cause an error
-message to be emitted by awk.
-
-setting feature default value
-
-Changes the default value of setting 'feature' to 'value'. There are a small
-number of settings listed at the top of pnglibconf.h, they are documented in the
-source code. Most of these values have performance implications for the library
-but most of them have no visible effect on the API. Some can also be overridden
-from the API.
-
-This method of building a customized pnglibconf.h is illustrated in
-contrib/pngminim/*. See the "$(PNGCONF):" target in the makefile and
-pngusr.dfa in these directories.
-
-C. Configuration using PNG_USER_CONFIG
-
-If \-DPNG_USER_CONFIG is added to the CPPFLAGS when pnglibconf.h is built,
-the file pngusr.h will automatically be included before the options in
-scripts/pnglibconf.dfa are processed. Your pngusr.h file should contain only
-macro definitions turning features on or off or setting settings.
-
-Apart from the global setting "everything = off" all the options listed above
-can be set using macros in pngusr.h:
-
-#define PNG_feature_SUPPORTED
-
-is equivalent to:
-
-option feature on
-
-#define PNG_NO_feature
-
-is equivalent to:
-
-option feature off
-
-#define PNG_feature value
-
-is equivalent to:
-
-setting feature default value
-
-Notice that in both cases, pngusr.dfa and pngusr.h, the contents of the
-pngusr file you supply override the contents of scripts/pnglibconf.dfa
-
-If confusing or incomprehensible behavior results it is possible to
-examine the intermediate file pnglibconf.dfn to find the full set of
-dependency information for each setting and option. Simply locate the
-feature in the file and read the C comments that precede it.
-
-This method is also illustrated in the contrib/pngminim/* makefiles and
-pngusr.h.
-
-.SH III. Reading
-
-We'll now walk you through the possible functions to call when reading
-in a PNG file sequentially, briefly explaining the syntax and purpose
-of each one. See example.c and png.h for more detail. While
-progressive reading is covered in the next section, you will still
-need some of the functions discussed in this section to read a PNG
-file.
-
-.SS Setup
-
-You will want to do the I/O initialization(*) before you get into libpng,
-so if it doesn't work, you don't have much to undo. Of course, you
-will also want to insure that you are, in fact, dealing with a PNG
-file. Libpng provides a simple check to see if a file is a PNG file.
-To use it, pass in the first 1 to 8 bytes of the file to the function
-png_sig_cmp(), and it will return 0 (false) if the bytes match the
-corresponding bytes of the PNG signature, or nonzero (true) otherwise.
-Of course, the more bytes you pass in, the greater the accuracy of the
-prediction.
-
-If you are intending to keep the file pointer open for use in libpng,
-you must ensure you don't read more than 8 bytes from the beginning
-of the file, and you also have to make a call to png_set_sig_bytes()
-with the number of bytes you read from the beginning. Libpng will
-then only check the bytes (if any) that your program didn't read.
-
-(*): If you are not using the standard I/O functions, you will need
-to replace them with custom functions. See the discussion under
-Customizing libpng.
-
- FILE *fp = fopen(file_name, "rb");
- if (!fp)
- {
- return (ERROR);
- }
-
- if (fread(header, 1, number, fp) != number)
- {
- return (ERROR);
- }
-
- is_png = !png_sig_cmp(header, 0, number);
- if (!is_png)
- {
- return (NOT_PNG);
- }
-
-Next, png_struct and png_info need to be allocated and initialized. In
-order to ensure that the size of these structures is correct even with a
-dynamically linked libpng, there are functions to initialize and
-allocate the structures. We also pass the library version, optional
-pointers to error handling functions, and a pointer to a data struct for
-use by the error functions, if necessary (the pointer and functions can
-be NULL if the default error handlers are to be used). See the section
-on Changes to Libpng below regarding the old initialization functions.
-The structure allocation functions quietly return NULL if they fail to
-create the structure, so your application should check for that.
-
- png_structp png_ptr = png_create_read_struct
- (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
- user_error_fn, user_warning_fn);
-
- if (!png_ptr)
- return (ERROR);
-
- png_infop info_ptr = png_create_info_struct(png_ptr);
-
- if (!info_ptr)
- {
- png_destroy_read_struct(&png_ptr,
- (png_infopp)NULL, (png_infopp)NULL);
- return (ERROR);
- }
-
-If you want to use your own memory allocation routines,
-use a libpng that was built with PNG_USER_MEM_SUPPORTED defined, and use
-png_create_read_struct_2() instead of png_create_read_struct():
-
- png_structp png_ptr = png_create_read_struct_2
- (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
- user_error_fn, user_warning_fn, (png_voidp)
- user_mem_ptr, user_malloc_fn, user_free_fn);
-
-The error handling routines passed to png_create_read_struct()
-and the memory alloc/free routines passed to png_create_struct_2()
-are only necessary if you are not using the libpng supplied error
-handling and memory alloc/free functions.
-
-When libpng encounters an error, it expects to longjmp back
-to your routine. Therefore, you will need to call setjmp and pass
-your png_jmpbuf(png_ptr). If you read the file from different
-routines, you will need to update the longjmp buffer every time you enter
-a new routine that will call a png_*() function.
-
-See your documentation of setjmp/longjmp for your compiler for more
-information on setjmp/longjmp. See the discussion on libpng error
-handling in the Customizing Libpng section below for more information
-on the libpng error handling. If an error occurs, and libpng longjmp's
-back to your setjmp, you will want to call png_destroy_read_struct() to
-free any memory.
-
- if (setjmp(png_jmpbuf(png_ptr)))
- {
- png_destroy_read_struct(&png_ptr, &info_ptr,
- &end_info);
- fclose(fp);
- return (ERROR);
- }
-
-Pass (png_infopp)NULL instead of &end_info if you didn't create
-an end_info structure.
-
-If you would rather avoid the complexity of setjmp/longjmp issues,
-you can compile libpng with PNG_NO_SETJMP, in which case
-errors will result in a call to PNG_ABORT() which defaults to abort().
-
-You can #define PNG_ABORT() to a function that does something
-more useful than abort(), as long as your function does not
-return.
-
-Now you need to set up the input code. The default for libpng is to
-use the C function fread(). If you use this, you will need to pass a
-valid FILE * in the function png_init_io(). Be sure that the file is
-opened in binary mode. If you wish to handle reading data in another
-way, you need not call the png_init_io() function, but you must then
-implement the libpng I/O methods discussed in the Customizing Libpng
-section below.
-
- png_init_io(png_ptr, fp);
-
-If you had previously opened the file and read any of the signature from
-the beginning in order to see if this was a PNG file, you need to let
-libpng know that there are some bytes missing from the start of the file.
-
- png_set_sig_bytes(png_ptr, number);
-
-You can change the zlib compression buffer size to be used while
-reading compressed data with
-
- png_set_compression_buffer_size(png_ptr, buffer_size);
-
-where the default size is 8192 bytes. Note that the buffer size
-is changed immediately and the buffer is reallocated immediately,
-instead of setting a flag to be acted upon later.
-
-If you want CRC errors to be handled in a different manner than
-the default, use
-
- png_set_crc_action(png_ptr, crit_action, ancil_action);
-
-The values for png_set_crc_action() say how libpng is to handle CRC errors in
-ancillary and critical chunks, and whether to use the data contained
-therein. Starting with libpng-1.6.26, this also governs how an ADLER32 error
-is handled while reading the IDAT chunk. Note that it is impossible to
-"discard" data in a critical chunk.
-
-Choices for (int) crit_action are
- PNG_CRC_DEFAULT 0 error/quit
- PNG_CRC_ERROR_QUIT 1 error/quit
- PNG_CRC_WARN_USE 3 warn/use data
- PNG_CRC_QUIET_USE 4 quiet/use data
- PNG_CRC_NO_CHANGE 5 use the current value
-
-Choices for (int) ancil_action are
- PNG_CRC_DEFAULT 0 error/quit
- PNG_CRC_ERROR_QUIT 1 error/quit
- PNG_CRC_WARN_DISCARD 2 warn/discard data
- PNG_CRC_WARN_USE 3 warn/use data
- PNG_CRC_QUIET_USE 4 quiet/use data
- PNG_CRC_NO_CHANGE 5 use the current value
-
-When the setting for crit_action is PNG_CRC_QUIET_USE, the CRC and ADLER32
-checksums are not only ignored, but they are not evaluated.
-
-.SS Setting up callback code
-
-You can set up a callback function to handle any unknown chunks in the
-input stream. You must supply the function
-
- read_chunk_callback(png_structp png_ptr,
- png_unknown_chunkp chunk);
- {
- /* The unknown chunk structure contains your
- chunk data, along with similar data for any other
- unknown chunks: */
-
- png_byte name[5];
- png_byte *data;
- png_size_t size;
-
- /* Note that libpng has already taken care of
- the CRC handling */
-
- /* put your code here. Search for your chunk in the
- unknown chunk structure, process it, and return one
- of the following: */
-
- return (\-n); /* chunk had an error */
- return (0); /* did not recognize */
- return (n); /* success */
- }
-
-(You can give your function another name that you like instead of
-"read_chunk_callback")
-
-To inform libpng about your function, use
-
- png_set_read_user_chunk_fn(png_ptr, user_chunk_ptr,
- read_chunk_callback);
-
-This names not only the callback function, but also a user pointer that
-you can retrieve with
-
- png_get_user_chunk_ptr(png_ptr);
-
-If you call the png_set_read_user_chunk_fn() function, then all unknown
-chunks which the callback does not handle will be saved when read. You can
-cause them to be discarded by returning '1' ("handled") instead of '0'. This
-behavior will change in libpng 1.7 and the default handling set by the
-png_set_keep_unknown_chunks() function, described below, will be used when the
-callback returns 0. If you want the existing behavior you should set the global
-default to PNG_HANDLE_CHUNK_IF_SAFE now; this is compatible with all current
-versions of libpng and with 1.7. Libpng 1.6 issues a warning if you keep the
-default, or PNG_HANDLE_CHUNK_NEVER, and the callback returns 0.
-
-At this point, you can set up a callback function that will be
-called after each row has been read, which you can use to control
-a progress meter or the like. It's demonstrated in pngtest.c.
-You must supply a function
-
- void read_row_callback(png_structp png_ptr,
- png_uint_32 row, int pass);
- {
- /* put your code here */
- }
-
-(You can give it another name that you like instead of "read_row_callback")
-
-To inform libpng about your function, use
-
- png_set_read_status_fn(png_ptr, read_row_callback);
-
-When this function is called the row has already been completely processed and
-the 'row' and 'pass' refer to the next row to be handled. For the
-non-interlaced case the row that was just handled is simply one less than the
-passed in row number, and pass will always be 0. For the interlaced case the
-same applies unless the row value is 0, in which case the row just handled was
-the last one from one of the preceding passes. Because interlacing may skip a
-pass you cannot be sure that the preceding pass is just 'pass\-1'; if you really
-need to know what the last pass is record (row,pass) from the callback and use
-the last recorded value each time.
-
-As with the user transform you can find the output row using the
-PNG_ROW_FROM_PASS_ROW macro.
-
-.SS Unknown-chunk handling
-
-Now you get to set the way the library processes unknown chunks in the
-input PNG stream. Both known and unknown chunks will be read. Normal
-behavior is that known chunks will be parsed into information in
-various info_ptr members while unknown chunks will be discarded. This
-behavior can be wasteful if your application will never use some known
-chunk types. To change this, you can call:
-
- png_set_keep_unknown_chunks(png_ptr, keep,
- chunk_list, num_chunks);
-
- keep - 0: default unknown chunk handling
- 1: ignore; do not keep
- 2: keep only if safe-to-copy
- 3: keep even if unsafe-to-copy
-
- You can use these definitions:
- PNG_HANDLE_CHUNK_AS_DEFAULT 0
- PNG_HANDLE_CHUNK_NEVER 1
- PNG_HANDLE_CHUNK_IF_SAFE 2
- PNG_HANDLE_CHUNK_ALWAYS 3
-
- chunk_list - list of chunks affected (a byte string,
- five bytes per chunk, NULL or '\0' if
- num_chunks is positive; ignored if
- numchunks <= 0).
-
- num_chunks - number of chunks affected; if 0, all
- unknown chunks are affected. If positive,
- only the chunks in the list are affected,
- and if negative all unknown chunks and
- all known chunks except for the IHDR,
- PLTE, tRNS, IDAT, and IEND chunks are
- affected.
-
-Unknown chunks declared in this way will be saved as raw data onto a
-list of png_unknown_chunk structures. If a chunk that is normally
-known to libpng is named in the list, it will be handled as unknown,
-according to the "keep" directive. If a chunk is named in successive
-instances of png_set_keep_unknown_chunks(), the final instance will
-take precedence. The IHDR and IEND chunks should not be named in
-chunk_list; if they are, libpng will process them normally anyway.
-If you know that your application will never make use of some particular
-chunks, use PNG_HANDLE_CHUNK_NEVER (or 1) as demonstrated below.
-
-Here is an example of the usage of png_set_keep_unknown_chunks(),
-where the private "vpAg" chunk will later be processed by a user chunk
-callback function:
-
- png_byte vpAg[5]={118, 112, 65, 103, (png_byte) '\0'};
-
- #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
- png_byte unused_chunks[]=
- {
- 104, 73, 83, 84, (png_byte) '\0', /* hIST */
- 105, 84, 88, 116, (png_byte) '\0', /* iTXt */
- 112, 67, 65, 76, (png_byte) '\0', /* pCAL */
- 115, 67, 65, 76, (png_byte) '\0', /* sCAL */
- 115, 80, 76, 84, (png_byte) '\0', /* sPLT */
- 116, 73, 77, 69, (png_byte) '\0', /* tIME */
- };
- #endif
-
- ...
-
- #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
- /* ignore all unknown chunks
- * (use global setting "2" for libpng16 and earlier):
- */
- png_set_keep_unknown_chunks(read_ptr, 2, NULL, 0);
-
- /* except for vpAg: */
- png_set_keep_unknown_chunks(read_ptr, 2, vpAg, 1);
-
- /* also ignore unused known chunks: */
- png_set_keep_unknown_chunks(read_ptr, 1, unused_chunks,
- (int)(sizeof unused_chunks)/5);
- #endif
-
-.SS User limits
-
-The PNG specification allows the width and height of an image to be as
-large as 2^(31\-1 (0x7fffffff), or about 2.147 billion rows and columns.
-For safety, libpng imposes a default limit of 1 million rows and columns.
-Larger images will be rejected immediately with a png_error() call. If
-you wish to change these limits, you can use
-
- png_set_user_limits(png_ptr, width_max, height_max);
-
-to set your own limits (libpng may reject some very wide images
-anyway because of potential buffer overflow conditions).
-
-You should put this statement after you create the PNG structure and
-before calling png_read_info(), png_read_png(), or png_process_data().
-
-When writing a PNG datastream, put this statement before calling
-png_write_info() or png_write_png().
-
-If you need to retrieve the limits that are being applied, use
-
- width_max = png_get_user_width_max(png_ptr);
- height_max = png_get_user_height_max(png_ptr);
-
-The PNG specification sets no limit on the number of ancillary chunks
-allowed in a PNG datastream. By default, libpng imposes a limit of
-a total of 1000 sPLT, tEXt, iTXt, zTXt, and unknown chunks to be stored.
-If you have set up both info_ptr and end_info_ptr, the limit applies
-separately to each. You can change the limit on the total number of such
-chunks that will be stored, with
-
- png_set_chunk_cache_max(png_ptr, user_chunk_cache_max);
-
-where 0x7fffffffL means unlimited. You can retrieve this limit with
-
- chunk_cache_max = png_get_chunk_cache_max(png_ptr);
-
-Libpng imposes a limit of 8 Megabytes (8,000,000 bytes) on the amount of
-memory that a compressed chunk other than IDAT can occupy, when decompressed.
-You can change this limit with
-
- png_set_chunk_malloc_max(png_ptr, user_chunk_malloc_max);
-
-and you can retrieve the limit with
-
- chunk_malloc_max = png_get_chunk_malloc_max(png_ptr);
-
-Any chunks that would cause either of these limits to be exceeded will
-be ignored.
-
-.SS Information about your system
-
-If you intend to display the PNG or to incorporate it in other image data you
-need to tell libpng information about your display or drawing surface so that
-libpng can convert the values in the image to match the display.
-
-From libpng-1.5.4 this information can be set before reading the PNG file
-header. In earlier versions png_set_gamma() existed but behaved incorrectly if
-called before the PNG file header had been read and png_set_alpha_mode() did not
-exist.
-
-If you need to support versions prior to libpng-1.5.4 test the version number
-as illustrated below using "PNG_LIBPNG_VER >= 10504" and follow the procedures
-described in the appropriate manual page.
-
-You give libpng the encoding expected by your system expressed as a 'gamma'
-value. You can also specify a default encoding for the PNG file in
-case the required information is missing from the file. By default libpng
-assumes that the PNG data matches your system, to keep this default call:
-
- png_set_gamma(png_ptr, screen_gamma, output_gamma);
-
-or you can use the fixed point equivalent:
-
- png_set_gamma_fixed(png_ptr, PNG_FP_1*screen_gamma,
- PNG_FP_1*output_gamma);
-
-If you don't know the gamma for your system it is probably 2.2 - a good
-approximation to the IEC standard for display systems (sRGB). If images are
-too contrasty or washed out you got the value wrong - check your system
-documentation!
-
-Many systems permit the system gamma to be changed via a lookup table in the
-display driver, a few systems, including older Macs, change the response by
-default. As of 1.5.4 three special values are available to handle common
-situations:
-
- PNG_DEFAULT_sRGB: Indicates that the system conforms to the
- IEC 61966-2-1 standard. This matches almost
- all systems.
- PNG_GAMMA_MAC_18: Indicates that the system is an older
- (pre Mac OS 10.6) Apple Macintosh system with
- the default settings.
- PNG_GAMMA_LINEAR: Just the fixed point value for 1.0 - indicates
- that the system expects data with no gamma
- encoding.
-
-You would use the linear (unencoded) value if you need to process the pixel
-values further because this avoids the need to decode and re-encode each
-component value whenever arithmetic is performed. A lot of graphics software
-uses linear values for this reason, often with higher precision component values
-to preserve overall accuracy.
-
-
-The output_gamma value expresses how to decode the output values, not how
-they are encoded. The values used correspond to the normal numbers used to
-describe the overall gamma of a computer display system; for example 2.2 for
-an sRGB conformant system. The values are scaled by 100000 in the _fixed
-version of the API (so 220000 for sRGB.)
-
-The inverse of the value is always used to provide a default for the PNG file
-encoding if it has no gAMA chunk and if png_set_gamma() has not been called
-to override the PNG gamma information.
-
-When the ALPHA_OPTIMIZED mode is selected the output gamma is used to encode
-opaque pixels however pixels with lower alpha values are not encoded,
-regardless of the output gamma setting.
-
-When the standard Porter Duff handling is requested with mode 1 the output
-encoding is set to be linear and the output_gamma value is only relevant
-as a default for input data that has no gamma information. The linear output
-encoding will be overridden if png_set_gamma() is called - the results may be
-highly unexpected!
-
-The following numbers are derived from the sRGB standard and the research
-behind it. sRGB is defined to be approximated by a PNG gAMA chunk value of
-0.45455 (1/2.2) for PNG. The value implicitly includes any viewing
-correction required to take account of any differences in the color
-environment of the original scene and the intended display environment; the
-value expresses how to *decode* the image for display, not how the original
-data was *encoded*.
-
-sRGB provides a peg for the PNG standard by defining a viewing environment.
-sRGB itself, and earlier TV standards, actually use a more complex transform
-(a linear portion then a gamma 2.4 power law) than PNG can express. (PNG is
-limited to simple power laws.) By saying that an image for direct display on
-an sRGB conformant system should be stored with a gAMA chunk value of 45455
-(11.3.3.2 and 11.3.3.5 of the ISO PNG specification) the PNG specification
-makes it possible to derive values for other display systems and
-environments.
-
-The Mac value is deduced from the sRGB based on an assumption that the actual
-extra viewing correction used in early Mac display systems was implemented as
-a power 1.45 lookup table.
-
-Any system where a programmable lookup table is used or where the behavior of
-the final display device characteristics can be changed requires system
-specific code to obtain the current characteristic. However this can be
-difficult and most PNG gamma correction only requires an approximate value.
-
-By default, if png_set_alpha_mode() is not called, libpng assumes that all
-values are unencoded, linear, values and that the output device also has a
-linear characteristic. This is only very rarely correct - it is invariably
-better to call png_set_alpha_mode() with PNG_DEFAULT_sRGB than rely on the
-default if you don't know what the right answer is!
-
-The special value PNG_GAMMA_MAC_18 indicates an older Mac system (pre Mac OS
-10.6) which used a correction table to implement a somewhat lower gamma on an
-otherwise sRGB system.
-
-Both these values are reserved (not simple gamma values) in order to allow
-more precise correction internally in the future.
-
-NOTE: the values can be passed to either the fixed or floating
-point APIs, but the floating point API will also accept floating point
-values.
-
-The second thing you may need to tell libpng about is how your system handles
-alpha channel information. Some, but not all, PNG files contain an alpha
-channel. To display these files correctly you need to compose the data onto a
-suitable background, as described in the PNG specification.
-
-Libpng only supports composing onto a single color (using png_set_background;
-see below). Otherwise you must do the composition yourself and, in this case,
-you may need to call png_set_alpha_mode:
-
- #if PNG_LIBPNG_VER >= 10504
- png_set_alpha_mode(png_ptr, mode, screen_gamma);
- #else
- png_set_gamma(png_ptr, screen_gamma, 1.0/screen_gamma);
- #endif
-
-The screen_gamma value is the same as the argument to png_set_gamma; however,
-how it affects the output depends on the mode. png_set_alpha_mode() sets the
-file gamma default to 1/screen_gamma, so normally you don't need to call
-png_set_gamma. If you need different defaults call png_set_gamma() before
-png_set_alpha_mode() - if you call it after it will override the settings made
-by png_set_alpha_mode().
-
-The mode is as follows:
-
- PNG_ALPHA_PNG: The data is encoded according to the PNG
-specification. Red, green and blue, or gray, components are
-gamma encoded color values and are not premultiplied by the
-alpha value. The alpha value is a linear measure of the
-contribution of the pixel to the corresponding final output pixel.
-
-You should normally use this format if you intend to perform
-color correction on the color values; most, maybe all, color
-correction software has no handling for the alpha channel and,
-anyway, the math to handle pre-multiplied component values is
-unnecessarily complex.
-
-Before you do any arithmetic on the component values you need
-to remove the gamma encoding and multiply out the alpha
-channel. See the PNG specification for more detail. It is
-important to note that when an image with an alpha channel is
-scaled, linear encoded, pre-multiplied component values must
-be used!
-
-The remaining modes assume you don't need to do any further color correction or
-that if you do, your color correction software knows all about alpha (it
-probably doesn't!). They 'associate' the alpha with the color information by
-storing color channel values that have been scaled by the alpha. The
-advantage is that the color channels can be resampled (the image can be
-scaled) in this form. The disadvantage is that normal practice is to store
-linear, not (gamma) encoded, values and this requires 16-bit channels for
-still images rather than the 8-bit channels that are just about sufficient if
-gamma encoding is used. In addition all non-transparent pixel values,
-including completely opaque ones, must be gamma encoded to produce the final
-image. These are the 'STANDARD', 'ASSOCIATED' or 'PREMULTIPLIED' modes
-described below (the latter being the two common names for associated alpha
-color channels). Note that PNG files always contain non-associated color
-channels; png_set_alpha_mode() with one of the modes causes the decoder to
-convert the pixels to an associated form before returning them to your
-application.
-
-Since it is not necessary to perform arithmetic on opaque color values so
-long as they are not to be resampled and are in the final color space it is
-possible to optimize the handling of alpha by storing the opaque pixels in
-the PNG format (adjusted for the output color space) while storing partially
-opaque pixels in the standard, linear, format. The accuracy required for
-standard alpha composition is relatively low, because the pixels are
-isolated, therefore typically the accuracy loss in storing 8-bit linear
-values is acceptable. (This is not true if the alpha channel is used to
-simulate transparency over large areas - use 16 bits or the PNG mode in
-this case!) This is the 'OPTIMIZED' mode. For this mode a pixel is
-treated as opaque only if the alpha value is equal to the maximum value.
-
- PNG_ALPHA_STANDARD: The data libpng produces is encoded in the
-standard way assumed by most correctly written graphics software.
-The gamma encoding will be removed by libpng and the
-linear component values will be pre-multiplied by the
-alpha channel.
-
-With this format the final image must be re-encoded to
-match the display gamma before the image is displayed.
-If your system doesn't do that, yet still seems to
-perform arithmetic on the pixels without decoding them,
-it is broken - check out the modes below.
-
-With PNG_ALPHA_STANDARD libpng always produces linear
-component values, whatever screen_gamma you supply. The
-screen_gamma value is, however, used as a default for
-the file gamma if the PNG file has no gamma information.
-
-If you call png_set_gamma() after png_set_alpha_mode() you
-will override the linear encoding. Instead the
-pre-multiplied pixel values will be gamma encoded but
-the alpha channel will still be linear. This may
-actually match the requirements of some broken software,
-but it is unlikely.
-
-While linear 8-bit data is often used it has
-insufficient precision for any image with a reasonable
-dynamic range. To avoid problems, and if your software
-supports it, use png_set_expand_16() to force all
-components to 16 bits.
-
- PNG_ALPHA_OPTIMIZED: This mode is the same as PNG_ALPHA_STANDARD
-except that completely opaque pixels are gamma encoded according to
-the screen_gamma value. Pixels with alpha less than 1.0
-will still have linear components.
-
-Use this format if you have control over your
-compositing software and so don't do other arithmetic
-(such as scaling) on the data you get from libpng. Your
-compositing software can simply copy opaque pixels to
-the output but still has linear values for the
-non-opaque pixels.
-
-In normal compositing, where the alpha channel encodes
-partial pixel coverage (as opposed to broad area
-translucency), the inaccuracies of the 8-bit
-representation of non-opaque pixels are irrelevant.
-
-You can also try this format if your software is broken;
-it might look better.
-
- PNG_ALPHA_BROKEN: This is PNG_ALPHA_STANDARD; however, all component
-values, including the alpha channel are gamma encoded. This is
-broken because, in practice, no implementation that uses this choice
-correctly undoes the encoding before handling alpha composition. Use this
-choice only if other serious errors in the software or hardware you use
-mandate it. In most cases of broken software or hardware the bug in the
-final display manifests as a subtle halo around composited parts of the
-image. You may not even perceive this as a halo; the composited part of
-the image may simply appear separate from the background, as though it had
-been cut out of paper and pasted on afterward.
-
-If you don't have to deal with bugs in software or hardware, or if you can fix
-them, there are three recommended ways of using png_set_alpha_mode():
-
- png_set_alpha_mode(png_ptr, PNG_ALPHA_PNG,
- screen_gamma);
-
-You can do color correction on the result (libpng does not currently
-support color correction internally). When you handle the alpha channel
-you need to undo the gamma encoding and multiply out the alpha.
-
- png_set_alpha_mode(png_ptr, PNG_ALPHA_STANDARD,
- screen_gamma);
- png_set_expand_16(png_ptr);
-
-If you are using the high level interface, don't call png_set_expand_16();
-instead pass PNG_TRANSFORM_EXPAND_16 to the interface.
-
-With this mode you can't do color correction, but you can do arithmetic,
-including composition and scaling, on the data without further processing.
-
- png_set_alpha_mode(png_ptr, PNG_ALPHA_OPTIMIZED,
- screen_gamma);
-
-You can avoid the expansion to 16-bit components with this mode, but you
-lose the ability to scale the image or perform other linear arithmetic.
-All you can do is compose the result onto a matching output. Since this
-mode is libpng-specific you also need to write your own composition
-software.
-
-The following are examples of calls to png_set_alpha_mode to achieve the
-required overall gamma correction and, where necessary, alpha
-premultiplication.
-
- png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
-
-This is the default libpng handling of the alpha channel - it is not
-pre-multiplied into the color components. In addition the call states
-that the output is for a sRGB system and causes all PNG files without gAMA
-chunks to be assumed to be encoded using sRGB.
-
- png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
-
-In this case the output is assumed to be something like an sRGB conformant
-display preceeded by a power-law lookup table of power 1.45. This is how
-early Mac systems behaved.
-
- png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_GAMMA_LINEAR);
-
-This is the classic Jim Blinn approach and will work in academic
-environments where everything is done by the book. It has the shortcoming
-of assuming that input PNG data with no gamma information is linear - this
-is unlikely to be correct unless the PNG files where generated locally.
-Most of the time the output precision will be so low as to show
-significant banding in dark areas of the image.
-
- png_set_expand_16(pp);
- png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_DEFAULT_sRGB);
-
-This is a somewhat more realistic Jim Blinn inspired approach. PNG files
-are assumed to have the sRGB encoding if not marked with a gamma value and
-the output is always 16 bits per component. This permits accurate scaling
-and processing of the data. If you know that your input PNG files were
-generated locally you might need to replace PNG_DEFAULT_sRGB with the
-correct value for your system.
-
- png_set_alpha_mode(pp, PNG_ALPHA_OPTIMIZED, PNG_DEFAULT_sRGB);
-
-If you just need to composite the PNG image onto an existing background
-and if you control the code that does this you can use the optimization
-setting. In this case you just copy completely opaque pixels to the
-output. For pixels that are not completely transparent (you just skip
-those) you do the composition math using png_composite or png_composite_16
-below then encode the resultant 8-bit or 16-bit values to match the output
-encoding.
-
- Other cases
-
-If neither the PNG nor the standard linear encoding work for you because
-of the software or hardware you use then you have a big problem. The PNG
-case will probably result in halos around the image. The linear encoding
-will probably result in a washed out, too bright, image (it's actually too
-contrasty.) Try the ALPHA_OPTIMIZED mode above - this will probably
-substantially reduce the halos. Alternatively try:
-
- png_set_alpha_mode(pp, PNG_ALPHA_BROKEN, PNG_DEFAULT_sRGB);
-
-This option will also reduce the halos, but there will be slight dark
-halos round the opaque parts of the image where the background is light.
-In the OPTIMIZED mode the halos will be light halos where the background
-is dark. Take your pick - the halos are unavoidable unless you can get
-your hardware/software fixed! (The OPTIMIZED approach is slightly
-faster.)
-
-When the default gamma of PNG files doesn't match the output gamma.
-If you have PNG files with no gamma information png_set_alpha_mode allows
-you to provide a default gamma, but it also sets the ouput gamma to the
-matching value. If you know your PNG files have a gamma that doesn't
-match the output you can take advantage of the fact that
-png_set_alpha_mode always sets the output gamma but only sets the PNG
-default if it is not already set:
-
- png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
- png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
-
-The first call sets both the default and the output gamma values, the
-second call overrides the output gamma without changing the default. This
-is easier than achieving the same effect with png_set_gamma. You must use
-PNG_ALPHA_PNG for the first call - internal checking in png_set_alpha will
-fire if more than one call to png_set_alpha_mode and png_set_background is
-made in the same read operation, however multiple calls with PNG_ALPHA_PNG
-are ignored.
-
-If you don't need, or can't handle, the alpha channel you can call
-png_set_background() to remove it by compositing against a fixed color. Don't
-call png_set_strip_alpha() to do this - it will leave spurious pixel values in
-transparent parts of this image.
-
- png_set_background(png_ptr, &background_color,
- PNG_BACKGROUND_GAMMA_SCREEN, 0, 1);
-
-The background_color is an RGB or grayscale value according to the data format
-libpng will produce for you. Because you don't yet know the format of the PNG
-file, if you call png_set_background at this point you must arrange for the
-format produced by libpng to always have 8-bit or 16-bit components and then
-store the color as an 8-bit or 16-bit color as appropriate. The color contains
-separate gray and RGB component values, so you can let libpng produce gray or
-RGB output according to the input format, but low bit depth grayscale images
-must always be converted to at least 8-bit format. (Even though low bit depth
-grayscale images can't have an alpha channel they can have a transparent
-color!)
-
-You set the transforms you need later, either as flags to the high level
-interface or libpng API calls for the low level interface. For reference the
-settings and API calls required are:
-
-8-bit values:
- PNG_TRANSFORM_SCALE_16 | PNG_EXPAND
- png_set_expand(png_ptr); png_set_scale_16(png_ptr);
-
- If you must get exactly the same inaccurate results
- produced by default in versions prior to libpng-1.5.4,
- use PNG_TRANSFORM_STRIP_16 and png_set_strip_16(png_ptr)
- instead.
-
-16-bit values:
- PNG_TRANSFORM_EXPAND_16
- png_set_expand_16(png_ptr);
-
-In either case palette image data will be expanded to RGB. If you just want
-color data you can add PNG_TRANSFORM_GRAY_TO_RGB or png_set_gray_to_rgb(png_ptr)
-to the list.
-
-Calling png_set_background before the PNG file header is read will not work
-prior to libpng-1.5.4. Because the failure may result in unexpected warnings or
-errors it is therefore much safer to call png_set_background after the head has
-been read. Unfortunately this means that prior to libpng-1.5.4 it cannot be
-used with the high level interface.
-
-.SS The high-level read interface
-
-At this point there are two ways to proceed; through the high-level
-read interface, or through a sequence of low-level read operations.
-You can use the high-level interface if (a) you are willing to read
-the entire image into memory, and (b) the input transformations
-you want to do are limited to the following set:
-
- PNG_TRANSFORM_IDENTITY No transformation
- PNG_TRANSFORM_SCALE_16 Strip 16-bit samples to
- 8-bit accurately
- PNG_TRANSFORM_STRIP_16 Chop 16-bit samples to
- 8-bit less accurately
- PNG_TRANSFORM_STRIP_ALPHA Discard the alpha channel
- PNG_TRANSFORM_PACKING Expand 1, 2 and 4-bit
- samples to bytes
- PNG_TRANSFORM_PACKSWAP Change order of packed
- pixels to LSB first
- PNG_TRANSFORM_EXPAND Perform set_expand()
- PNG_TRANSFORM_INVERT_MONO Invert monochrome images
- PNG_TRANSFORM_SHIFT Normalize pixels to the
- sBIT depth
- PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA
- to BGRA
- PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA
- to AG
- PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
- to transparency
- PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
- PNG_TRANSFORM_GRAY_TO_RGB Expand grayscale samples
- to RGB (or GA to RGBA)
- PNG_TRANSFORM_EXPAND_16 Expand samples to 16 bits
-
-(This excludes setting a background color, doing gamma transformation,
-quantizing, and setting filler.) If this is the case, simply do this:
-
- png_read_png(png_ptr, info_ptr, png_transforms, NULL)
-
-where png_transforms is an integer containing the bitwise OR of some
-set of transformation flags. This call is equivalent to png_read_info(),
-followed the set of transformations indicated by the transform mask,
-then png_read_image(), and finally png_read_end().
-
-(The final parameter of this call is not yet used. Someday it might point
-to transformation parameters required by some future input transform.)
-
-You must use png_transforms and not call any png_set_transform() functions
-when you use png_read_png().
-
-After you have called png_read_png(), you can retrieve the image data
-with
-
- row_pointers = png_get_rows(png_ptr, info_ptr);
-
-where row_pointers is an array of pointers to the pixel data for each row:
-
- png_bytep row_pointers[height];
-
-If you know your image size and pixel size ahead of time, you can allocate
-row_pointers prior to calling png_read_png() with
-
- if (height > PNG_UINT_32_MAX/(sizeof (png_byte)))
- png_error (png_ptr,
- "Image is too tall to process in memory");
-
- if (width > PNG_UINT_32_MAX/pixel_size)
- png_error (png_ptr,
- "Image is too wide to process in memory");
-
- row_pointers = png_malloc(png_ptr,
- height*(sizeof (png_bytep)));
-
- for (int i=0; i<height, i++)
- row_pointers[i]=NULL; /* security precaution */
-
- for (int i=0; i<height, i++)
- row_pointers[i]=png_malloc(png_ptr,
- width*pixel_size);
-
- png_set_rows(png_ptr, info_ptr, &row_pointers);
-
-Alternatively you could allocate your image in one big block and define
-row_pointers[i] to point into the proper places in your block, but first
-be sure that your platform is able to allocate such a large buffer:
-
- /* Guard against integer overflow */
- if (height > PNG_SIZE_MAX/(width*pixel_size)) {
- png_error(png_ptr,"image_data buffer would be too large");
- }
-
- png_bytep buffer=png_malloc(png_ptr,height*width*pixel_size);
-
- for (int i=0; i<height, i++)
- row_pointers[i]=buffer+i*width*pixel_size;
-
- png_set_rows(png_ptr, info_ptr, &row_pointers);
-
-If you use png_set_rows(), the application is responsible for freeing
-row_pointers (and row_pointers[i], if they were separately allocated).
-
-If you don't allocate row_pointers ahead of time, png_read_png() will
-do it, and it'll be free'ed by libpng when you call png_destroy_*().
-
-.SS The low-level read interface
-
-If you are going the low-level route, you are now ready to read all
-the file information up to the actual image data. You do this with a
-call to png_read_info().
-
- png_read_info(png_ptr, info_ptr);
-
-This will process all chunks up to but not including the image data.
-
-This also copies some of the data from the PNG file into the decode structure
-for use in later transformations. Important information copied in is:
-
-1) The PNG file gamma from the gAMA chunk. This overwrites the default value
-provided by an earlier call to png_set_gamma or png_set_alpha_mode.
-
-2) Prior to libpng-1.5.4 the background color from a bKGd chunk. This
-damages the information provided by an earlier call to png_set_background
-resulting in unexpected behavior. Libpng-1.5.4 no longer does this.
-
-3) The number of significant bits in each component value. Libpng uses this to
-optimize gamma handling by reducing the internal lookup table sizes.
-
-4) The transparent color information from a tRNS chunk. This can be modified by
-a later call to png_set_tRNS.
-
-.SS Querying the info structure
-
-Functions are used to get the information from the info_ptr once it
-has been read. Note that these fields may not be completely filled
-in until png_read_end() has read the chunk data following the image.
-
- png_get_IHDR(png_ptr, info_ptr, &width, &height,
- &bit_depth, &color_type, &interlace_type,
- &compression_type, &filter_method);
-
- width - holds the width of the image
- in pixels (up to 2^31).
-
- height - holds the height of the image
- in pixels (up to 2^31).
-
- bit_depth - holds the bit depth of one of the
- image channels. (valid values are
- 1, 2, 4, 8, 16 and depend also on
- the color_type. See also
- significant bits (sBIT) below).
-
- color_type - describes which color/alpha channels
- are present.
- PNG_COLOR_TYPE_GRAY
- (bit depths 1, 2, 4, 8, 16)
- PNG_COLOR_TYPE_GRAY_ALPHA
- (bit depths 8, 16)
- PNG_COLOR_TYPE_PALETTE
- (bit depths 1, 2, 4, 8)
- PNG_COLOR_TYPE_RGB
- (bit_depths 8, 16)
- PNG_COLOR_TYPE_RGB_ALPHA
- (bit_depths 8, 16)
-
- PNG_COLOR_MASK_PALETTE
- PNG_COLOR_MASK_COLOR
- PNG_COLOR_MASK_ALPHA
-
- interlace_type - (PNG_INTERLACE_NONE or
- PNG_INTERLACE_ADAM7)
-
- compression_type - (must be PNG_COMPRESSION_TYPE_BASE
- for PNG 1.0)
-
- filter_method - (must be PNG_FILTER_TYPE_BASE
- for PNG 1.0, and can also be
- PNG_INTRAPIXEL_DIFFERENCING if
- the PNG datastream is embedded in
- a MNG-1.0 datastream)
-
- Any of width, height, color_type, bit_depth,
- interlace_type, compression_type, or filter_method can
- be NULL if you are not interested in their values.
-
- Note that png_get_IHDR() returns 32-bit data into
- the application's width and height variables.
- This is an unsafe situation if these are not png_uint_32
- variables. In such situations, the
- png_get_image_width() and png_get_image_height()
- functions described below are safer.
-
- width = png_get_image_width(png_ptr,
- info_ptr);
-
- height = png_get_image_height(png_ptr,
- info_ptr);
-
- bit_depth = png_get_bit_depth(png_ptr,
- info_ptr);
-
- color_type = png_get_color_type(png_ptr,
- info_ptr);
-
- interlace_type = png_get_interlace_type(png_ptr,
- info_ptr);
-
- compression_type = png_get_compression_type(png_ptr,
- info_ptr);
-
- filter_method = png_get_filter_type(png_ptr,
- info_ptr);
-
- channels = png_get_channels(png_ptr, info_ptr);
-
- channels - number of channels of info for the
- color type (valid values are 1 (GRAY,
- PALETTE), 2 (GRAY_ALPHA), 3 (RGB),
- 4 (RGB_ALPHA or RGB + filler byte))
-
- rowbytes = png_get_rowbytes(png_ptr, info_ptr);
-
- rowbytes - number of bytes needed to hold a row
- This value, the bit_depth, color_type,
- and the number of channels can change
- if you use transforms such as
- png_set_expand(). See
- png_read_update_info(), below.
-
- signature = png_get_signature(png_ptr, info_ptr);
-
- signature - holds the signature read from the
- file (if any). The data is kept in
- the same offset it would be if the
- whole signature were read (i.e. if an
- application had already read in 4
- bytes of signature before starting
- libpng, the remaining 4 bytes would
- be in signature[4] through signature[7]
- (see png_set_sig_bytes())).
-
-These are also important, but their validity depends on whether the chunk
-has been read. The png_get_valid(png_ptr, info_ptr, PNG_INFO_<chunk>) and
-png_get_<chunk>(png_ptr, info_ptr, ...) functions return non-zero if the
-data has been read, or zero if it is missing. The parameters to the
-png_get_<chunk> are set directly if they are simple data types, or a
-pointer into the info_ptr is returned for any complex types.
-
-The colorspace data from gAMA, cHRM, sRGB, iCCP, and sBIT chunks
-is simply returned to give the application information about how the
-image was encoded. Libpng itself only does transformations using the file
-gamma when combining semitransparent pixels with the background color, and,
-since libpng-1.6.0, when converting between 8-bit sRGB and 16-bit linear pixels
-within the simplified API. Libpng also uses the file gamma when converting
-RGB to gray, beginning with libpng-1.0.5, if the application calls
-png_set_rgb_to_gray()).
-
- png_get_PLTE(png_ptr, info_ptr, &palette,
- &num_palette);
-
- palette - the palette for the file
- (array of png_color)
-
- num_palette - number of entries in the palette
-
- png_get_gAMA(png_ptr, info_ptr, &file_gamma);
- png_get_gAMA_fixed(png_ptr, info_ptr, &int_file_gamma);
-
- file_gamma - the gamma at which the file is
- written (PNG_INFO_gAMA)
-
- int_file_gamma - 100,000 times the gamma at which the
- file is written
-
- png_get_cHRM(png_ptr, info_ptr, &white_x, &white_y, &red_x,
- &red_y, &green_x, &green_y, &blue_x, &blue_y)
- png_get_cHRM_XYZ(png_ptr, info_ptr, &red_X, &red_Y, &red_Z,
- &green_X, &green_Y, &green_Z, &blue_X, &blue_Y,
- &blue_Z)
- png_get_cHRM_fixed(png_ptr, info_ptr, &int_white_x,
- &int_white_y, &int_red_x, &int_red_y,
- &int_green_x, &int_green_y, &int_blue_x,
- &int_blue_y)
- png_get_cHRM_XYZ_fixed(png_ptr, info_ptr, &int_red_X, &int_red_Y,
- &int_red_Z, &int_green_X, &int_green_Y,
- &int_green_Z, &int_blue_X, &int_blue_Y,
- &int_blue_Z)
-
- {white,red,green,blue}_{x,y}
- A color space encoding specified using the
- chromaticities of the end points and the
- white point. (PNG_INFO_cHRM)
-
- {red,green,blue}_{X,Y,Z}
- A color space encoding specified using the
- encoding end points - the CIE tristimulus
- specification of the intended color of the red,
- green and blue channels in the PNG RGB data.
- The white point is simply the sum of the three
- end points. (PNG_INFO_cHRM)
-
- png_get_sRGB(png_ptr, info_ptr, &srgb_intent);
-
- srgb_intent - the rendering intent (PNG_INFO_sRGB)
- The presence of the sRGB chunk
- means that the pixel data is in the
- sRGB color space. This chunk also
- implies specific values of gAMA and
- cHRM.
-
- png_get_iCCP(png_ptr, info_ptr, &name,
- &compression_type, &profile, &proflen);
-
- name - The profile name.
-
- compression_type - The compression type; always
- PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
- You may give NULL to this argument to
- ignore it.
-
- profile - International Color Consortium color
- profile data. May contain NULs.
-
- proflen - length of profile data in bytes.
-
- png_get_sBIT(png_ptr, info_ptr, &sig_bit);
-
- sig_bit - the number of significant bits for
- (PNG_INFO_sBIT) each of the gray,
- red, green, and blue channels,
- whichever are appropriate for the
- given color type (png_color_16)
-
- png_get_tRNS(png_ptr, info_ptr, &trans_alpha,
- &num_trans, &trans_color);
-
- trans_alpha - array of alpha (transparency)
- entries for palette (PNG_INFO_tRNS)
-
- num_trans - number of transparent entries
- (PNG_INFO_tRNS)
-
- trans_color - graylevel or color sample values of
- the single transparent color for
- non-paletted images (PNG_INFO_tRNS)
-
- png_get_eXIf(png_ptr, info_ptr, &exif);
- (PNG_INFO_eXIf)
-
- exif - Exif profile (array of png_byte)
-
- png_get_hIST(png_ptr, info_ptr, &hist);
- (PNG_INFO_hIST)
-
- hist - histogram of palette (array of
- png_uint_16)
-
- png_get_tIME(png_ptr, info_ptr, &mod_time);
-
- mod_time - time image was last modified
- (PNG_VALID_tIME)
-
- png_get_bKGD(png_ptr, info_ptr, &background);
-
- background - background color (of type
- png_color_16p) (PNG_VALID_bKGD)
- valid 16-bit red, green and blue
- values, regardless of color_type
-
- num_comments = png_get_text(png_ptr, info_ptr,
- &text_ptr, &num_text);
-
- num_comments - number of comments
-
- text_ptr - array of png_text holding image
- comments
-
- text_ptr[i].compression - type of compression used
- on "text" PNG_TEXT_COMPRESSION_NONE
- PNG_TEXT_COMPRESSION_zTXt
- PNG_ITXT_COMPRESSION_NONE
- PNG_ITXT_COMPRESSION_zTXt
-
- text_ptr[i].key - keyword for comment. Must contain
- 1-79 characters.
-
- text_ptr[i].text - text comments for current
- keyword. Can be empty.
-
- text_ptr[i].text_length - length of text string,
- after decompression, 0 for iTXt
-
- text_ptr[i].itxt_length - length of itxt string,
- after decompression, 0 for tEXt/zTXt
-
- text_ptr[i].lang - language of comment (empty
- string for unknown).
-
- text_ptr[i].lang_key - keyword in UTF-8
- (empty string for unknown).
-
- Note that the itxt_length, lang, and lang_key
- members of the text_ptr structure only exist when the
- library is built with iTXt chunk support. Prior to
- libpng-1.4.0 the library was built by default without
- iTXt support. Also note that when iTXt is supported,
- they contain NULL pointers when the "compression"
- field contains PNG_TEXT_COMPRESSION_NONE or
- PNG_TEXT_COMPRESSION_zTXt.
-
- num_text - number of comments (same as
- num_comments; you can put NULL here
- to avoid the duplication)
-
- Note while png_set_text() will accept text, language,
- and translated keywords that can be NULL pointers, the
- structure returned by png_get_text will always contain
- regular zero-terminated C strings. They might be
- empty strings but they will never be NULL pointers.
-
- num_spalettes = png_get_sPLT(png_ptr, info_ptr,
- &palette_ptr);
-
- num_spalettes - number of sPLT chunks read.
-
- palette_ptr - array of palette structures holding
- contents of one or more sPLT chunks
- read.
-
- png_get_oFFs(png_ptr, info_ptr, &offset_x, &offset_y,
- &unit_type);
-
- offset_x - positive offset from the left edge
- of the screen (can be negative)
-
- offset_y - positive offset from the top edge
- of the screen (can be negative)
-
- unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
-
- png_get_pHYs(png_ptr, info_ptr, &res_x, &res_y,
- &unit_type);
-
- res_x - pixels/unit physical resolution in
- x direction
-
- res_y - pixels/unit physical resolution in
- x direction
-
- unit_type - PNG_RESOLUTION_UNKNOWN,
- PNG_RESOLUTION_METER
-
- png_get_sCAL(png_ptr, info_ptr, &unit, &width,
- &height)
-
- unit - physical scale units (an integer)
-
- width - width of a pixel in physical scale units
-
- height - height of a pixel in physical scale units
- (width and height are doubles)
-
- png_get_sCAL_s(png_ptr, info_ptr, &unit, &width,
- &height)
-
- unit - physical scale units (an integer)
-
- width - width of a pixel in physical scale units
- (expressed as a string)
-
- height - height of a pixel in physical scale units
- (width and height are strings like "2.54")
-
- num_unknown_chunks = png_get_unknown_chunks(png_ptr,
- info_ptr, &unknowns)
-
- unknowns - array of png_unknown_chunk
- structures holding unknown chunks
-
- unknowns[i].name - name of unknown chunk
-
- unknowns[i].data - data of unknown chunk
-
- unknowns[i].size - size of unknown chunk's data
-
- unknowns[i].location - position of chunk in file
-
- The value of "i" corresponds to the order in which the
- chunks were read from the PNG file or inserted with the
- png_set_unknown_chunks() function.
-
- The value of "location" is a bitwise "or" of
-
- PNG_HAVE_IHDR (0x01)
- PNG_HAVE_PLTE (0x02)
- PNG_AFTER_IDAT (0x08)
-
-The data from the pHYs chunk can be retrieved in several convenient
-forms:
-
- res_x = png_get_x_pixels_per_meter(png_ptr,
- info_ptr)
-
- res_y = png_get_y_pixels_per_meter(png_ptr,
- info_ptr)
-
- res_x_and_y = png_get_pixels_per_meter(png_ptr,
- info_ptr)
-
- res_x = png_get_x_pixels_per_inch(png_ptr,
- info_ptr)
-
- res_y = png_get_y_pixels_per_inch(png_ptr,
- info_ptr)
-
- res_x_and_y = png_get_pixels_per_inch(png_ptr,
- info_ptr)
-
- aspect_ratio = png_get_pixel_aspect_ratio(png_ptr,
- info_ptr)
-
- Each of these returns 0 [signifying "unknown"] if
- the data is not present or if res_x is 0;
- res_x_and_y is 0 if res_x != res_y
-
- Note that because of the way the resolutions are
- stored internally, the inch conversions won't
- come out to exactly even number. For example,
- 72 dpi is stored as 0.28346 pixels/meter, and
- when this is retrieved it is 71.9988 dpi, so
- be sure to round the returned value appropriately
- if you want to display a reasonable-looking result.
-
-The data from the oFFs chunk can be retrieved in several convenient
-forms:
-
- x_offset = png_get_x_offset_microns(png_ptr, info_ptr);
-
- y_offset = png_get_y_offset_microns(png_ptr, info_ptr);
-
- x_offset = png_get_x_offset_inches(png_ptr, info_ptr);
-
- y_offset = png_get_y_offset_inches(png_ptr, info_ptr);
-
- Each of these returns 0 [signifying "unknown" if both
- x and y are 0] if the data is not present or if the
- chunk is present but the unit is the pixel. The
- remark about inexact inch conversions applies here
- as well, because a value in inches can't always be
- converted to microns and back without some loss
- of precision.
-
-For more information, see the
-PNG specification for chunk contents. Be careful with trusting
-rowbytes, as some of the transformations could increase the space
-needed to hold a row (expand, filler, gray_to_rgb, etc.).
-See png_read_update_info(), below.
-
-A quick word about text_ptr and num_text. PNG stores comments in
-keyword/text pairs, one pair per chunk, with no limit on the number
-of text chunks, and a 2^31 byte limit on their size. While there are
-suggested keywords, there is no requirement to restrict the use to these
-strings. It is strongly suggested that keywords and text be sensible
-to humans (that's the point), so don't use abbreviations. Non-printing
-symbols are not allowed. See the PNG specification for more details.
-There is also no requirement to have text after the keyword.
-
-Keywords should be limited to 79 Latin-1 characters without leading or
-trailing spaces, but non-consecutive spaces are allowed within the
-keyword. It is possible to have the same keyword any number of times.
-The text_ptr is an array of png_text structures, each holding a
-pointer to a language string, a pointer to a keyword and a pointer to
-a text string. The text string, language code, and translated
-keyword may be empty or NULL pointers. The keyword/text
-pairs are put into the array in the order that they are received.
-However, some or all of the text chunks may be after the image, so, to
-make sure you have read all the text chunks, don't mess with these
-until after you read the stuff after the image. This will be
-mentioned again below in the discussion that goes with png_read_end().
-
-.SS Input transformations
-
-After you've read the header information, you can set up the library
-to handle any special transformations of the image data. The various
-ways to transform the data will be described in the order that they
-should occur. This is important, as some of these change the color
-type and/or bit depth of the data, and some others only work on
-certain color types and bit depths.
-
-Transformations you request are ignored if they don't have any meaning for a
-particular input data format. However some transformations can have an effect
-as a result of a previous transformation. If you specify a contradictory set of
-transformations, for example both adding and removing the alpha channel, you
-cannot predict the final result.
-
-The color used for the transparency values should be supplied in the same
-format/depth as the current image data. It is stored in the same format/depth
-as the image data in a tRNS chunk, so this is what libpng expects for this data.
-
-The color used for the background value depends on the need_expand argument as
-described below.
-
-Data will be decoded into the supplied row buffers packed into bytes
-unless the library has been told to transform it into another format.
-For example, 4 bit/pixel paletted or grayscale data will be returned
-2 pixels/byte with the leftmost pixel in the high-order bits of the byte,
-unless png_set_packing() is called. 8-bit RGB data will be stored
-in RGB RGB RGB format unless png_set_filler() or png_set_add_alpha()
-is called to insert filler bytes, either before or after each RGB triplet.
-
-16-bit RGB data will be returned RRGGBB RRGGBB, with the most significant
-byte of the color value first, unless png_set_scale_16() is called to
-transform it to regular RGB RGB triplets, or png_set_filler() or
-png_set_add alpha() is called to insert two filler bytes, either before
-or after each RRGGBB triplet. Similarly, 8-bit or 16-bit grayscale data can
-be modified with png_set_filler(), png_set_add_alpha(), png_set_strip_16(),
-or png_set_scale_16().
-
-The following code transforms grayscale images of less than 8 to 8 bits,
-changes paletted images to RGB, and adds a full alpha channel if there is
-transparency information in a tRNS chunk. This is most useful on
-grayscale images with bit depths of 2 or 4 or if there is a multiple-image
-viewing application that wishes to treat all images in the same way.
-
- if (color_type == PNG_COLOR_TYPE_PALETTE)
- png_set_palette_to_rgb(png_ptr);
-
- if (png_get_valid(png_ptr, info_ptr,
- PNG_INFO_tRNS)) png_set_tRNS_to_alpha(png_ptr);
-
- if (color_type == PNG_COLOR_TYPE_GRAY &&
- bit_depth < 8) png_set_expand_gray_1_2_4_to_8(png_ptr);
-
-The first two functions are actually aliases for png_set_expand(), added
-in libpng version 1.0.4, with the function names expanded to improve code
-readability. In some future version they may actually do different
-things.
-
-As of libpng version 1.2.9, png_set_expand_gray_1_2_4_to_8() was
-added. It expands the sample depth without changing tRNS to alpha.
-
-As of libpng version 1.5.2, png_set_expand_16() was added. It behaves as
-png_set_expand(); however, the resultant channels have 16 bits rather than 8.
-Use this when the output color or gray channels are made linear to avoid fairly
-severe accuracy loss.
-
- if (bit_depth < 16)
- png_set_expand_16(png_ptr);
-
-PNG can have files with 16 bits per channel. If you only can handle
-8 bits per channel, this will strip the pixels down to 8-bit.
-
- if (bit_depth == 16)
-#if PNG_LIBPNG_VER >= 10504
- png_set_scale_16(png_ptr);
-#else
- png_set_strip_16(png_ptr);
-#endif
-
-(The more accurate "png_set_scale_16()" API became available in libpng version
-1.5.4).
-
-If you need to process the alpha channel on the image separately from the image
-data (for example if you convert it to a bitmap mask) it is possible to have
-libpng strip the channel leaving just RGB or gray data:
-
- if (color_type & PNG_COLOR_MASK_ALPHA)
- png_set_strip_alpha(png_ptr);
-
-If you strip the alpha channel you need to find some other way of dealing with
-the information. If, instead, you want to convert the image to an opaque
-version with no alpha channel use png_set_background; see below.
-
-As of libpng version 1.5.2, almost all useful expansions are supported, the
-major ommissions are conversion of grayscale to indexed images (which can be
-done trivially in the application) and conversion of indexed to grayscale (which
-can be done by a trivial manipulation of the palette.)
-
-In the following table, the 01 means grayscale with depth<8, 31 means
-indexed with depth<8, other numerals represent the color type, "T" means
-the tRNS chunk is present, A means an alpha channel is present, and O
-means tRNS or alpha is present but all pixels in the image are opaque.
-
- FROM 01 31 0 0T 0O 2 2T 2O 3 3T 3O 4A 4O 6A 6O
- TO
- 01 - [G] - - - - - - - - - - - - -
- 31 [Q] Q [Q] [Q] [Q] Q Q Q Q Q Q [Q] [Q] Q Q
- 0 1 G + . . G G G G G G B B GB GB
- 0T lt Gt t + . Gt G G Gt G G Bt Bt GBt GBt
- 0O lt Gt t . + Gt Gt G Gt Gt G Bt Bt GBt GBt
- 2 C P C C C + . . C - - CB CB B B
- 2T Ct - Ct C C t + t - - - CBt CBt Bt Bt
- 2O Ct - Ct C C t t + - - - CBt CBt Bt Bt
- 3 [Q] p [Q] [Q] [Q] Q Q Q + . . [Q] [Q] Q Q
- 3T [Qt] p [Qt][Q] [Q] Qt Qt Qt t + t [Qt][Qt] Qt Qt
- 3O [Qt] p [Qt][Q] [Q] Qt Qt Qt t t + [Qt][Qt] Qt Qt
- 4A lA G A T T GA GT GT GA GT GT + BA G GBA
- 4O lA GBA A T T GA GT GT GA GT GT BA + GBA G
- 6A CA PA CA C C A T tT PA P P C CBA + BA
- 6O CA PBA CA C C A tT T PA P P CBA C BA +
-
-Within the matrix,
- "+" identifies entries where 'from' and 'to' are the same.
- "-" means the transformation is not supported.
- "." means nothing is necessary (a tRNS chunk can just be ignored).
- "t" means the transformation is obtained by png_set_tRNS.
- "A" means the transformation is obtained by png_set_add_alpha().
- "X" means the transformation is obtained by png_set_expand().
- "1" means the transformation is obtained by
- png_set_expand_gray_1_2_4_to_8() (and by png_set_expand()
- if there is no transparency in the original or the final
- format).
- "C" means the transformation is obtained by png_set_gray_to_rgb().
- "G" means the transformation is obtained by png_set_rgb_to_gray().
- "P" means the transformation is obtained by
- png_set_expand_palette_to_rgb().
- "p" means the transformation is obtained by png_set_packing().
- "Q" means the transformation is obtained by png_set_quantize().
- "T" means the transformation is obtained by
- png_set_tRNS_to_alpha().
- "B" means the transformation is obtained by
- png_set_background(), or png_strip_alpha().
-
-When an entry has multiple transforms listed all are required to cause the
-right overall transformation. When two transforms are separated by a comma
-either will do the job. When transforms are enclosed in [] the transform should
-do the job but this is currently unimplemented - a different format will result
-if the suggested transformations are used.
-
-In PNG files, the alpha channel in an image
-is the level of opacity. If you need the alpha channel in an image to
-be the level of transparency instead of opacity, you can invert the
-alpha channel (or the tRNS chunk data) after it's read, so that 0 is
-fully opaque and 255 (in 8-bit or paletted images) or 65535 (in 16-bit
-images) is fully transparent, with
-
- png_set_invert_alpha(png_ptr);
-
-PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
-they can, resulting in, for example, 8 pixels per byte for 1 bit
-files. This code expands to 1 pixel per byte without changing the
-values of the pixels:
-
- if (bit_depth < 8)
- png_set_packing(png_ptr);
-
-PNG files have possible bit depths of 1, 2, 4, 8, and 16. All pixels
-stored in a PNG image have been "scaled" or "shifted" up to the next
-higher possible bit depth (e.g. from 5 bits/sample in the range [0,31]
-to 8 bits/sample in the range [0, 255]). However, it is also possible
-to convert the PNG pixel data back to the original bit depth of the
-image. This call reduces the pixels back down to the original bit depth:
-
- png_color_8p sig_bit;
-
- if (png_get_sBIT(png_ptr, info_ptr, &sig_bit))
- png_set_shift(png_ptr, sig_bit);
-
-PNG files store 3-color pixels in red, green, blue order. This code
-changes the storage of the pixels to blue, green, red:
-
- if (color_type == PNG_COLOR_TYPE_RGB ||
- color_type == PNG_COLOR_TYPE_RGB_ALPHA)
- png_set_bgr(png_ptr);
-
-PNG files store RGB pixels packed into 3 or 6 bytes. This code expands them
-into 4 or 8 bytes for windowing systems that need them in this format:
-
- if (color_type == PNG_COLOR_TYPE_RGB)
- png_set_filler(png_ptr, filler, PNG_FILLER_BEFORE);
-
-where "filler" is the 8-bit or 16-bit number to fill with, and the location
-is either PNG_FILLER_BEFORE or PNG_FILLER_AFTER, depending upon whether
-you want the filler before the RGB or after. When filling an 8-bit pixel,
-the least significant 8 bits of the number are used, if a 16-bit number is
-supplied. This transformation does not affect images that already have full
-alpha channels. To add an opaque alpha channel, use filler=0xffff and
-PNG_FILLER_AFTER which will generate RGBA pixels.
-
-Note that png_set_filler() does not change the color type. If you want
-to do that, you can add a true alpha channel with
-
- if (color_type == PNG_COLOR_TYPE_RGB ||
- color_type == PNG_COLOR_TYPE_GRAY)
- png_set_add_alpha(png_ptr, filler, PNG_FILLER_AFTER);
-
-where "filler" contains the alpha value to assign to each pixel.
-The png_set_add_alpha() function was added in libpng-1.2.7.
-
-If you are reading an image with an alpha channel, and you need the
-data as ARGB instead of the normal PNG format RGBA:
-
- if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
- png_set_swap_alpha(png_ptr);
-
-For some uses, you may want a grayscale image to be represented as
-RGB. This code will do that conversion:
-
- if (color_type == PNG_COLOR_TYPE_GRAY ||
- color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
- png_set_gray_to_rgb(png_ptr);
-
-Conversely, you can convert an RGB or RGBA image to grayscale or grayscale
-with alpha.
-
- if (color_type == PNG_COLOR_TYPE_RGB ||
- color_type == PNG_COLOR_TYPE_RGB_ALPHA)
- png_set_rgb_to_gray(png_ptr, error_action,
- double red_weight, double green_weight);
-
- error_action = 1: silently do the conversion
-
- error_action = 2: issue a warning if the original
- image has any pixel where
- red != green or red != blue
-
- error_action = 3: issue an error and abort the
- conversion if the original
- image has any pixel where
- red != green or red != blue
-
- red_weight: weight of red component
-
- green_weight: weight of green component
- If either weight is negative, default
- weights are used.
-
-In the corresponding fixed point API the red_weight and green_weight values are
-simply scaled by 100,000:
-
- png_set_rgb_to_gray(png_ptr, error_action,
- png_fixed_point red_weight,
- png_fixed_point green_weight);
-
-If you have set error_action = 1 or 2, you can
-later check whether the image really was gray, after processing
-the image rows, with the png_get_rgb_to_gray_status(png_ptr) function.
-It will return a png_byte that is zero if the image was gray or
-1 if there were any non-gray pixels. Background and sBIT data
-will be silently converted to grayscale, using the green channel
-data for sBIT, regardless of the error_action setting.
-
-The default values come from the PNG file cHRM chunk if present; otherwise, the
-defaults correspond to the ITU-R recommendation 709, and also the sRGB color
-space, as recommended in the Charles Poynton's Colour FAQ,
-Copyright (c) 2006-11-28 Charles Poynton, in section 9:
-
-<http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html#RTFToC9>
-
- Y = 0.2126 * R + 0.7152 * G + 0.0722 * B
-
-Previous versions of this document, 1998 through 2002, recommended a slightly
-different formula:
-
- Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
-
-Libpng uses an integer approximation:
-
- Y = (6968 * R + 23434 * G + 2366 * B)/32768
-
-The calculation is done in a linear colorspace, if the image gamma
-can be determined.
-
-The png_set_background() function has been described already; it tells libpng to
-composite images with alpha or simple transparency against the supplied
-background color. For compatibility with versions of libpng earlier than
-libpng-1.5.4 it is recommended that you call the function after reading the file
-header, even if you don't want to use the color in a bKGD chunk, if one exists.
-
-If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid),
-you may use this color, or supply another color more suitable for
-the current display (e.g., the background color from a web page). You
-need to tell libpng how the color is represented, both the format of the
-component values in the color (the number of bits) and the gamma encoding of the
-color. The function takes two arguments, background_gamma_mode and need_expand
-to convey this information; however, only two combinations are likely to be
-useful:
-
- png_color_16 my_background;
- png_color_16p image_background;
-
- if (png_get_bKGD(png_ptr, info_ptr, &image_background))
- png_set_background(png_ptr, image_background,
- PNG_BACKGROUND_GAMMA_FILE, 1/*needs to be expanded*/, 1);
- else
- png_set_background(png_ptr, &my_background,
- PNG_BACKGROUND_GAMMA_SCREEN, 0/*do not expand*/, 1);
-
-The second call was described above - my_background is in the format of the
-final, display, output produced by libpng. Because you now know the format of
-the PNG it is possible to avoid the need to choose either 8-bit or 16-bit
-output and to retain palette images (the palette colors will be modified
-appropriately and the tRNS chunk removed.) However, if you are doing this,
-take great care not to ask for transformations without checking first that
-they apply!
-
-In the first call the background color has the original bit depth and color type
-of the PNG file. So, for palette images the color is supplied as a palette
-index and for low bit greyscale images the color is a reduced bit value in
-image_background->gray.
-
-If you didn't call png_set_gamma() before reading the file header, for example
-if you need your code to remain compatible with older versions of libpng prior
-to libpng-1.5.4, this is the place to call it.
-
-Do not call it if you called png_set_alpha_mode(); doing so will damage the
-settings put in place by png_set_alpha_mode(). (If png_set_alpha_mode() is
-supported then you can certainly do png_set_gamma() before reading the PNG
-header.)
-
-This API unconditionally sets the screen and file gamma values, so it will
-override the value in the PNG file unless it is called before the PNG file
-reading starts. For this reason you must always call it with the PNG file
-value when you call it in this position:
-
- if (png_get_gAMA(png_ptr, info_ptr, &file_gamma))
- png_set_gamma(png_ptr, screen_gamma, file_gamma);
-
- else
- png_set_gamma(png_ptr, screen_gamma, 0.45455);
-
-If you need to reduce an RGB file to a paletted file, or if a paletted
-file has more entries than will fit on your screen, png_set_quantize()
-will do that. Note that this is a simple match quantization that merely
-finds the closest color available. This should work fairly well with
-optimized palettes, but fairly badly with linear color cubes. If you
-pass a palette that is larger than maximum_colors, the file will
-reduce the number of colors in the palette so it will fit into
-maximum_colors. If there is a histogram, libpng will use it to make
-more intelligent choices when reducing the palette. If there is no
-histogram, it may not do as good a job.
-
- if (color_type & PNG_COLOR_MASK_COLOR)
- {
- if (png_get_valid(png_ptr, info_ptr,
- PNG_INFO_PLTE))
- {
- png_uint_16p histogram = NULL;
-
- png_get_hIST(png_ptr, info_ptr,
- &histogram);
- png_set_quantize(png_ptr, palette, num_palette,
- max_screen_colors, histogram, 1);
- }
-
- else
- {
- png_color std_color_cube[MAX_SCREEN_COLORS] =
- { ... colors ... };
-
- png_set_quantize(png_ptr, std_color_cube,
- MAX_SCREEN_COLORS, MAX_SCREEN_COLORS,
- NULL,0);
- }
- }
-
-PNG files describe monochrome as black being zero and white being one.
-The following code will reverse this (make black be one and white be
-zero):
-
- if (bit_depth == 1 && color_type == PNG_COLOR_TYPE_GRAY)
- png_set_invert_mono(png_ptr);
-
-This function can also be used to invert grayscale and gray-alpha images:
-
- if (color_type == PNG_COLOR_TYPE_GRAY ||
- color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
- png_set_invert_mono(png_ptr);
-
-PNG files store 16-bit pixels in network byte order (big-endian,
-ie. most significant bits first). This code changes the storage to the
-other way (little-endian, i.e. least significant bits first, the
-way PCs store them):
-
- if (bit_depth == 16)
- png_set_swap(png_ptr);
-
-If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
-need to change the order the pixels are packed into bytes, you can use:
-
- if (bit_depth < 8)
- png_set_packswap(png_ptr);
-
-Finally, you can write your own transformation function if none of
-the existing ones meets your needs. This is done by setting a callback
-with
-
- png_set_read_user_transform_fn(png_ptr,
- read_transform_fn);
-
-You must supply the function
-
- void read_transform_fn(png_structp png_ptr, png_row_infop
- row_info, png_bytep data)
-
-See pngtest.c for a working example. Your function will be called
-after all of the other transformations have been processed. Take care with
-interlaced images if you do the interlace yourself - the width of the row is the
-width in 'row_info', not the overall image width.
-
-If supported, libpng provides two information routines that you can use to find
-where you are in processing the image:
-
- png_get_current_pass_number(png_structp png_ptr);
- png_get_current_row_number(png_structp png_ptr);
-
-Don't try using these outside a transform callback - firstly they are only
-supported if user transforms are supported, secondly they may well return
-unexpected results unless the row is actually being processed at the moment they
-are called.
-
-With interlaced
-images the value returned is the row in the input sub-image image. Use
-PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
-find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass).
-
-The discussion of interlace handling above contains more information on how to
-use these values.
-
-You can also set up a pointer to a user structure for use by your
-callback function, and you can inform libpng that your transform
-function will change the number of channels or bit depth with the
-function
-
- png_set_user_transform_info(png_ptr, user_ptr,
- user_depth, user_channels);
-
-The user's application, not libpng, is responsible for allocating and
-freeing any memory required for the user structure.
-
-You can retrieve the pointer via the function
-png_get_user_transform_ptr(). For example:
-
- voidp read_user_transform_ptr =
- png_get_user_transform_ptr(png_ptr);
-
-The last thing to handle is interlacing; this is covered in detail below,
-but you must call the function here if you want libpng to handle expansion
-of the interlaced image.
-
- number_of_passes = png_set_interlace_handling(png_ptr);
-
-After setting the transformations, libpng can update your png_info
-structure to reflect any transformations you've requested with this
-call.
-
- png_read_update_info(png_ptr, info_ptr);
-
-This is most useful to update the info structure's rowbytes
-field so you can use it to allocate your image memory. This function
-will also update your palette with the correct screen_gamma and
-background if these have been given with the calls above. You may
-only call png_read_update_info() once with a particular info_ptr.
-
-After you call png_read_update_info(), you can allocate any
-memory you need to hold the image. The row data is simply
-raw byte data for all forms of images. As the actual allocation
-varies among applications, no example will be given. If you
-are allocating one large chunk, you will need to build an
-array of pointers to each row, as it will be needed for some
-of the functions below.
-
-Be sure that your platform can allocate the buffer that you'll need.
-libpng internally checks for oversize width, but you'll need to
-do your own check for number_of_rows*width*pixel_size if you are using
-a multiple-row buffer:
-
- /* Guard against integer overflow */
- if (number_of_rows > PNG_SIZE_MAX/(width*pixel_size)) {
- png_error(png_ptr,"image_data buffer would be too large");
- }
-
-Remember: Before you call png_read_update_info(), the png_get_*()
-functions return the values corresponding to the original PNG image.
-After you call png_read_update_info the values refer to the image
-that libpng will output. Consequently you must call all the png_set_
-functions before you call png_read_update_info(). This is particularly
-important for png_set_interlace_handling() - if you are going to call
-png_read_update_info() you must call png_set_interlace_handling() before
-it unless you want to receive interlaced output.
-
-.SS Reading image data
-
-After you've allocated memory, you can read the image data.
-The simplest way to do this is in one function call. If you are
-allocating enough memory to hold the whole image, you can just
-call png_read_image() and libpng will read in all the image data
-and put it in the memory area supplied. You will need to pass in
-an array of pointers to each row.
-
-This function automatically handles interlacing, so you don't
-need to call png_set_interlace_handling() (unless you call
-png_read_update_info()) or call this function multiple times, or any
-of that other stuff necessary with png_read_rows().
-
- png_read_image(png_ptr, row_pointers);
-
-where row_pointers is:
-
- png_bytep row_pointers[height];
-
-You can point to void or char or whatever you use for pixels.
-
-If you don't want to read in the whole image at once, you can
-use png_read_rows() instead. If there is no interlacing (check
-interlace_type == PNG_INTERLACE_NONE), this is simple:
-
- png_read_rows(png_ptr, row_pointers, NULL,
- number_of_rows);
-
-where row_pointers is the same as in the png_read_image() call.
-
-If you are doing this just one row at a time, you can do this with
-a single row_pointer instead of an array of row_pointers:
-
- png_bytep row_pointer = row;
- png_read_row(png_ptr, row_pointer, NULL);
-
-If the file is interlaced (interlace_type != 0 in the IHDR chunk), things
-get somewhat harder. The only current (PNG Specification version 1.2)
-interlacing type for PNG is (interlace_type == PNG_INTERLACE_ADAM7);
-a somewhat complicated 2D interlace scheme, known as Adam7, that
-breaks down an image into seven smaller images of varying size, based
-on an 8x8 grid. This number is defined (from libpng 1.5) as
-PNG_INTERLACE_ADAM7_PASSES in png.h
-
-libpng can fill out those images or it can give them to you "as is".
-It is almost always better to have libpng handle the interlacing for you.
-If you want the images filled out, there are two ways to do that. The one
-mentioned in the PNG specification is to expand each pixel to cover
-those pixels that have not been read yet (the "rectangle" method).
-This results in a blocky image for the first pass, which gradually
-smooths out as more pixels are read. The other method is the "sparkle"
-method, where pixels are drawn only in their final locations, with the
-rest of the image remaining whatever colors they were initialized to
-before the start of the read. The first method usually looks better,
-but tends to be slower, as there are more pixels to put in the rows.
-
-If, as is likely, you want libpng to expand the images, call this before
-calling png_start_read_image() or png_read_update_info():
-
- if (interlace_type == PNG_INTERLACE_ADAM7)
- number_of_passes
- = png_set_interlace_handling(png_ptr);
-
-This will return the number of passes needed. Currently, this is seven,
-but may change if another interlace type is added. This function can be
-called even if the file is not interlaced, where it will return one pass.
-You then need to read the whole image 'number_of_passes' times. Each time
-will distribute the pixels from the current pass to the correct place in
-the output image, so you need to supply the same rows to png_read_rows in
-each pass.
-
-If you are not going to display the image after each pass, but are
-going to wait until the entire image is read in, use the sparkle
-effect. This effect is faster and the end result of either method
-is exactly the same. If you are planning on displaying the image
-after each pass, the "rectangle" effect is generally considered the
-better looking one.
-
-If you only want the "sparkle" effect, just call png_read_row() or
-png_read_rows() as
-normal, with the third parameter NULL. Make sure you make pass over
-the image number_of_passes times, and you don't change the data in the
-rows between calls. You can change the locations of the data, just
-not the data. Each pass only writes the pixels appropriate for that
-pass, and assumes the data from previous passes is still valid.
-
- png_read_rows(png_ptr, row_pointers, NULL,
- number_of_rows);
- or
- png_read_row(png_ptr, row_pointers, NULL);
-
-If you only want the first effect (the rectangles), do the same as
-before except pass the row buffer in the third parameter, and leave
-the second parameter NULL.
-
- png_read_rows(png_ptr, NULL, row_pointers,
- number_of_rows);
- or
- png_read_row(png_ptr, NULL, row_pointers);
-
-If you don't want libpng to handle the interlacing details, just call
-png_read_rows() PNG_INTERLACE_ADAM7_PASSES times to read in all the images.
-Each of the images is a valid image by itself; however, you will almost
-certainly need to distribute the pixels from each sub-image to the
-correct place. This is where everything gets very tricky.
-
-If you want to retrieve the separate images you must pass the correct
-number of rows to each successive call of png_read_rows(). The calculation
-gets pretty complicated for small images, where some sub-images may
-not even exist because either their width or height ends up zero.
-libpng provides two macros to help you in 1.5 and later versions:
-
- png_uint_32 width = PNG_PASS_COLS(image_width, pass_number);
- png_uint_32 height = PNG_PASS_ROWS(image_height, pass_number);
-
-Respectively these tell you the width and height of the sub-image
-corresponding to the numbered pass. 'pass' is in in the range 0 to 6 -
-this can be confusing because the specification refers to the same passes
-as 1 to 7! Be careful, you must check both the width and height before
-calling png_read_rows() and not call it for that pass if either is zero.
-
-You can, of course, read each sub-image row by row. If you want to
-produce optimal code to make a pixel-by-pixel transformation of an
-interlaced image this is the best approach; read each row of each pass,
-transform it, and write it out to a new interlaced image.
-
-If you want to de-interlace the image yourself libpng provides further
-macros to help that tell you where to place the pixels in the output image.
-Because the interlacing scheme is rectangular - sub-image pixels are always
-arranged on a rectangular grid - all you need to know for each pass is the
-starting column and row in the output image of the first pixel plus the
-spacing between each pixel. As of libpng 1.5 there are four macros to
-retrieve this information:
-
- png_uint_32 x = PNG_PASS_START_COL(pass);
- png_uint_32 y = PNG_PASS_START_ROW(pass);
- png_uint_32 xStep = 1U << PNG_PASS_COL_SHIFT(pass);
- png_uint_32 yStep = 1U << PNG_PASS_ROW_SHIFT(pass);
-
-These allow you to write the obvious loop:
-
- png_uint_32 input_y = 0;
- png_uint_32 output_y = PNG_PASS_START_ROW(pass);
-
- while (output_y < output_image_height)
- {
- png_uint_32 input_x = 0;
- png_uint_32 output_x = PNG_PASS_START_COL(pass);
-
- while (output_x < output_image_width)
- {
- image[output_y][output_x] =
- subimage[pass][input_y][input_x++];
-
- output_x += xStep;
- }
-
- ++input_y;
- output_y += yStep;
- }
-
-Notice that the steps between successive output rows and columns are
-returned as shifts. This is possible because the pixels in the subimages
-are always a power of 2 apart - 1, 2, 4 or 8 pixels - in the original
-image. In practice you may need to directly calculate the output coordinate
-given an input coordinate. libpng provides two further macros for this
-purpose:
-
- png_uint_32 output_x = PNG_COL_FROM_PASS_COL(input_x, pass);
- png_uint_32 output_y = PNG_ROW_FROM_PASS_ROW(input_y, pass);
-
-Finally a pair of macros are provided to tell you if a particular image
-row or column appears in a given pass:
-
- int col_in_pass = PNG_COL_IN_INTERLACE_PASS(output_x, pass);
- int row_in_pass = PNG_ROW_IN_INTERLACE_PASS(output_y, pass);
-
-Bear in mind that you will probably also need to check the width and height
-of the pass in addition to the above to be sure the pass even exists!
-
-With any luck you are convinced by now that you don't want to do your own
-interlace handling. In reality normally the only good reason for doing this
-is if you are processing PNG files on a pixel-by-pixel basis and don't want
-to load the whole file into memory when it is interlaced.
-
-libpng includes a test program, pngvalid, that illustrates reading and
-writing of interlaced images. If you can't get interlacing to work in your
-code and don't want to leave it to libpng (the recommended approach), see
-how pngvalid.c does it.
-
-.SS Finishing a sequential read
-
-After you are finished reading the image through the
-low-level interface, you can finish reading the file.
-
-If you want to use a different crc action for handling CRC errors in
-chunks after the image data, you can call png_set_crc_action()
-again at this point.
-
-If you are interested in comments or time, which may be stored either
-before or after the image data, you should pass the separate png_info
-struct if you want to keep the comments from before and after the image
-separate.
-
- png_infop end_info = png_create_info_struct(png_ptr);
-
- if (!end_info)
- {
- png_destroy_read_struct(&png_ptr, &info_ptr,
- (png_infopp)NULL);
- return (ERROR);
- }
-
- png_read_end(png_ptr, end_info);
-
-If you are not interested, you should still call png_read_end()
-but you can pass NULL, avoiding the need to create an end_info structure.
-If you do this, libpng will not process any chunks after IDAT other than
-skipping over them and perhaps (depending on whether you have called
-png_set_crc_action) checking their CRCs while looking for the IEND chunk.
-
- png_read_end(png_ptr, (png_infop)NULL);
-
-If you don't call png_read_end(), then your file pointer will be
-left pointing to the first chunk after the last IDAT, which is probably
-not what you want if you expect to read something beyond the end of
-the PNG datastream.
-
-When you are done, you can free all memory allocated by libpng like this:
-
- png_destroy_read_struct(&png_ptr, &info_ptr,
- &end_info);
-
-or, if you didn't create an end_info structure,
-
- png_destroy_read_struct(&png_ptr, &info_ptr,
- (png_infopp)NULL);
-
-It is also possible to individually free the info_ptr members that
-point to libpng-allocated storage with the following function:
-
- png_free_data(png_ptr, info_ptr, mask, seq)
-
- mask - identifies data to be freed, a mask
- containing the bitwise OR of one or
- more of
- PNG_FREE_PLTE, PNG_FREE_TRNS,
- PNG_FREE_HIST, PNG_FREE_ICCP,
- PNG_FREE_PCAL, PNG_FREE_ROWS,
- PNG_FREE_SCAL, PNG_FREE_SPLT,
- PNG_FREE_TEXT, PNG_FREE_UNKN,
- or simply PNG_FREE_ALL
-
- seq - sequence number of item to be freed
- (\-1 for all items)
-
-This function may be safely called when the relevant storage has
-already been freed, or has not yet been allocated, or was allocated
-by the user and not by libpng, and will in those cases do nothing.
-The "seq" parameter is ignored if only one item of the selected data
-type, such as PLTE, is allowed. If "seq" is not \-1, and multiple items
-are allowed for the data type identified in the mask, such as text or
-sPLT, only the n'th item in the structure is freed, where n is "seq".
-
-The default behavior is only to free data that was allocated internally
-by libpng. This can be changed, so that libpng will not free the data,
-or so that it will free data that was allocated by the user with png_malloc()
-or png_calloc() and passed in via a png_set_*() function, with
-
- png_data_freer(png_ptr, info_ptr, freer, mask)
-
- freer - one of
- PNG_DESTROY_WILL_FREE_DATA
- PNG_SET_WILL_FREE_DATA
- PNG_USER_WILL_FREE_DATA
-
- mask - which data elements are affected
- same choices as in png_free_data()
-
-This function only affects data that has already been allocated.
-You can call this function after reading the PNG data but before calling
-any png_set_*() functions, to control whether the user or the png_set_*()
-function is responsible for freeing any existing data that might be present,
-and again after the png_set_*() functions to control whether the user
-or png_destroy_*() is supposed to free the data. When the user assumes
-responsibility for libpng-allocated data, the application must use
-png_free() to free it, and when the user transfers responsibility to libpng
-for data that the user has allocated, the user must have used png_malloc()
-or png_calloc() to allocate it.
-
-If you allocated your row_pointers in a single block, as suggested above in
-the description of the high level read interface, you must not transfer
-responsibility for freeing it to the png_set_rows or png_read_destroy function,
-because they would also try to free the individual row_pointers[i].
-
-If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
-separately, do not transfer responsibility for freeing text_ptr to libpng,
-because when libpng fills a png_text structure it combines these members with
-the key member, and png_free_data() will free only text_ptr.key. Similarly,
-if you transfer responsibility for free'ing text_ptr from libpng to your
-application, your application must not separately free those members.
-
-The png_free_data() function will turn off the "valid" flag for anything
-it frees. If you need to turn the flag off for a chunk that was freed by
-your application instead of by libpng, you can use
-
- png_set_invalid(png_ptr, info_ptr, mask);
-
- mask - identifies the chunks to be made invalid,
- containing the bitwise OR of one or
- more of
- PNG_INFO_gAMA, PNG_INFO_sBIT,
- PNG_INFO_cHRM, PNG_INFO_PLTE,
- PNG_INFO_tRNS, PNG_INFO_bKGD,
- PNG_INFO_eXIf,
- PNG_INFO_hIST, PNG_INFO_pHYs,
- PNG_INFO_oFFs, PNG_INFO_tIME,
- PNG_INFO_pCAL, PNG_INFO_sRGB,
- PNG_INFO_iCCP, PNG_INFO_sPLT,
- PNG_INFO_sCAL, PNG_INFO_IDAT
-
-For a more compact example of reading a PNG image, see the file example.c.
-
-.SS Reading PNG files progressively
-
-The progressive reader is slightly different from the non-progressive
-reader. Instead of calling png_read_info(), png_read_rows(), and
-png_read_end(), you make one call to png_process_data(), which calls
-callbacks when it has the info, a row, or the end of the image. You
-set up these callbacks with png_set_progressive_read_fn(). You don't
-have to worry about the input/output functions of libpng, as you are
-giving the library the data directly in png_process_data(). I will
-assume that you have read the section on reading PNG files above,
-so I will only highlight the differences (although I will show
-all of the code).
-
-png_structp png_ptr;
-png_infop info_ptr;
-
- /* An example code fragment of how you would
- initialize the progressive reader in your
- application. */
- int
- initialize_png_reader()
- {
- png_ptr = png_create_read_struct
- (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
- user_error_fn, user_warning_fn);
-
- if (!png_ptr)
- return (ERROR);
-
- info_ptr = png_create_info_struct(png_ptr);
-
- if (!info_ptr)
- {
- png_destroy_read_struct(&png_ptr,
- (png_infopp)NULL, (png_infopp)NULL);
- return (ERROR);
- }
-
- if (setjmp(png_jmpbuf(png_ptr)))
- {
- png_destroy_read_struct(&png_ptr, &info_ptr,
- (png_infopp)NULL);
- return (ERROR);
- }
-
- /* This one's new. You can provide functions
- to be called when the header info is valid,
- when each row is completed, and when the image
- is finished. If you aren't using all functions,
- you can specify NULL parameters. Even when all
- three functions are NULL, you need to call
- png_set_progressive_read_fn(). You can use
- any struct as the user_ptr (cast to a void pointer
- for the function call), and retrieve the pointer
- from inside the callbacks using the function
-
- png_get_progressive_ptr(png_ptr);
-
- which will return a void pointer, which you have
- to cast appropriately.
- */
- png_set_progressive_read_fn(png_ptr, (void *)user_ptr,
- info_callback, row_callback, end_callback);
-
- return 0;
- }
-
- /* A code fragment that you call as you receive blocks
- of data */
- int
- process_data(png_bytep buffer, png_uint_32 length)
- {
- if (setjmp(png_jmpbuf(png_ptr)))
- {
- png_destroy_read_struct(&png_ptr, &info_ptr,
- (png_infopp)NULL);
- return (ERROR);
- }
-
- /* This one's new also. Simply give it a chunk
- of data from the file stream (in order, of
- course). On machines with segmented memory
- models machines, don't give it any more than
- 64K. The library seems to run fine with sizes
- of 4K. Although you can give it much less if
- necessary (I assume you can give it chunks of
- 1 byte, I haven't tried less than 256 bytes
- yet). When this function returns, you may
- want to display any rows that were generated
- in the row callback if you don't already do
- so there.
- */
- png_process_data(png_ptr, info_ptr, buffer, length);
-
- /* At this point you can call png_process_data_skip if
- you want to handle data the library will skip yourself;
- it simply returns the number of bytes to skip (and stops
- libpng skipping that number of bytes on the next
- png_process_data call).
- return 0;
- }
-
- /* This function is called (as set by
- png_set_progressive_read_fn() above) when enough data
- has been supplied so all of the header has been
- read.
- */
- void
- info_callback(png_structp png_ptr, png_infop info)
- {
- /* Do any setup here, including setting any of
- the transformations mentioned in the Reading
- PNG files section. For now, you _must_ call
- either png_start_read_image() or
- png_read_update_info() after all the
- transformations are set (even if you don't set
- any). You may start getting rows before
- png_process_data() returns, so this is your
- last chance to prepare for that.
-
- This is where you turn on interlace handling,
- assuming you don't want to do it yourself.
-
- If you need to you can stop the processing of
- your original input data at this point by calling
- png_process_data_pause. This returns the number
- of unprocessed bytes from the last png_process_data
- call - it is up to you to ensure that the next call
- sees these bytes again. If you don't want to bother
- with this you can get libpng to cache the unread
- bytes by setting the 'save' parameter (see png.h) but
- then libpng will have to copy the data internally.
- */
- }
-
- /* This function is called when each row of image
- data is complete */
- void
- row_callback(png_structp png_ptr, png_bytep new_row,
- png_uint_32 row_num, int pass)
- {
- /* If the image is interlaced, and you turned
- on the interlace handler, this function will
- be called for every row in every pass. Some
- of these rows will not be changed from the
- previous pass. When the row is not changed,
- the new_row variable will be NULL. The rows
- and passes are called in order, so you don't
- really need the row_num and pass, but I'm
- supplying them because it may make your life
- easier.
-
- If you did not turn on interlace handling then
- the callback is called for each row of each
- sub-image when the image is interlaced. In this
- case 'row_num' is the row in the sub-image, not
- the row in the output image as it is in all other
- cases.
-
- For the non-NULL rows of interlaced images when
- you have switched on libpng interlace handling,
- you must call png_progressive_combine_row()
- passing in the row and the old row. You can
- call this function for NULL rows (it will just
- return) and for non-interlaced images (it just
- does the memcpy for you) if it will make the
- code easier. Thus, you can just do this for
- all cases if you switch on interlace handling;
- */
-
- png_progressive_combine_row(png_ptr, old_row,
- new_row);
-
- /* where old_row is what was displayed
- previously for the row. Note that the first
- pass (pass == 0, really) will completely cover
- the old row, so the rows do not have to be
- initialized. After the first pass (and only
- for interlaced images), you will have to pass
- the current row, and the function will combine
- the old row and the new row.
-
- You can also call png_process_data_pause in this
- callback - see above.
- */
- }
-
- void
- end_callback(png_structp png_ptr, png_infop info)
- {
- /* This function is called after the whole image
- has been read, including any chunks after the
- image (up to and including the IEND). You
- will usually have the same info chunk as you
- had in the header, although some data may have
- been added to the comments and time fields.
-
- Most people won't do much here, perhaps setting
- a flag that marks the image as finished.
- */
- }
-
-
-
-.SH IV. Writing
-
-Much of this is very similar to reading. However, everything of
-importance is repeated here, so you won't have to constantly look
-back up in the reading section to understand writing.
-
-.SS Setup
-
-You will want to do the I/O initialization before you get into libpng,
-so if it doesn't work, you don't have anything to undo. If you are not
-using the standard I/O functions, you will need to replace them with
-custom writing functions. See the discussion under Customizing libpng.
-
- FILE *fp = fopen(file_name, "wb");
-
- if (!fp)
- return (ERROR);
-
-Next, png_struct and png_info need to be allocated and initialized.
-As these can be both relatively large, you may not want to store these
-on the stack, unless you have stack space to spare. Of course, you
-will want to check if they return NULL. If you are also reading,
-you won't want to name your read structure and your write structure
-both "png_ptr"; you can call them anything you like, such as
-"read_ptr" and "write_ptr". Look at pngtest.c, for example.
-
- png_structp png_ptr = png_create_write_struct
- (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
- user_error_fn, user_warning_fn);
-
- if (!png_ptr)
- return (ERROR);
-
- png_infop info_ptr = png_create_info_struct(png_ptr);
- if (!info_ptr)
- {
- png_destroy_write_struct(&png_ptr,
- (png_infopp)NULL);
- return (ERROR);
- }
-
-If you want to use your own memory allocation routines,
-define PNG_USER_MEM_SUPPORTED and use
-png_create_write_struct_2() instead of png_create_write_struct():
-
- png_structp png_ptr = png_create_write_struct_2
- (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
- user_error_fn, user_warning_fn, (png_voidp)
- user_mem_ptr, user_malloc_fn, user_free_fn);
-
-After you have these structures, you will need to set up the
-error handling. When libpng encounters an error, it expects to
-longjmp() back to your routine. Therefore, you will need to call
-setjmp() and pass the png_jmpbuf(png_ptr). If you
-write the file from different routines, you will need to update
-the png_jmpbuf(png_ptr) every time you enter a new routine that will
-call a png_*() function. See your documentation of setjmp/longjmp
-for your compiler for more information on setjmp/longjmp. See
-the discussion on libpng error handling in the Customizing Libpng
-section below for more information on the libpng error handling.
-
- if (setjmp(png_jmpbuf(png_ptr)))
- {
- png_destroy_write_struct(&png_ptr, &info_ptr);
- fclose(fp);
- return (ERROR);
- }
- ...
- return;
-
-If you would rather avoid the complexity of setjmp/longjmp issues,
-you can compile libpng with PNG_NO_SETJMP, in which case
-errors will result in a call to PNG_ABORT() which defaults to abort().
-
-You can #define PNG_ABORT() to a function that does something
-more useful than abort(), as long as your function does not
-return.
-
-Checking for invalid palette index on write was added at libpng
-1.5.10. If a pixel contains an invalid (out-of-range) index libpng issues
-a benign error. This is enabled by default because this condition is an
-error according to the PNG specification, Clause 11.3.2, but the error can
-be ignored in each png_ptr with
-
- png_set_check_for_invalid_index(png_ptr, 0);
-
-If the error is ignored, or if png_benign_error() treats it as a warning,
-any invalid pixels are written as-is by the encoder, resulting in an
-invalid PNG datastream as output. In this case the application is
-responsible for ensuring that the pixel indexes are in range when it writes
-a PLTE chunk with fewer entries than the bit depth would allow.
-
-Now you need to set up the output code. The default for libpng is to
-use the C function fwrite(). If you use this, you will need to pass a
-valid FILE * in the function png_init_io(). Be sure that the file is
-opened in binary mode. Again, if you wish to handle writing data in
-another way, see the discussion on libpng I/O handling in the Customizing
-Libpng section below.
-
- png_init_io(png_ptr, fp);
-
-If you are embedding your PNG into a datastream such as MNG, and don't
-want libpng to write the 8-byte signature, or if you have already
-written the signature in your application, use
-
- png_set_sig_bytes(png_ptr, 8);
-
-to inform libpng that it should not write a signature.
-
-.SS Write callbacks
-
-At this point, you can set up a callback function that will be
-called after each row has been written, which you can use to control
-a progress meter or the like. It's demonstrated in pngtest.c.
-You must supply a function
-
- void write_row_callback(png_structp png_ptr, png_uint_32 row,
- int pass);
- {
- /* put your code here */
- }
-
-(You can give it another name that you like instead of "write_row_callback")
-
-To inform libpng about your function, use
-
- png_set_write_status_fn(png_ptr, write_row_callback);
-
-When this function is called the row has already been completely processed and
-it has also been written out. The 'row' and 'pass' refer to the next row to be
-handled. For the
-non-interlaced case the row that was just handled is simply one less than the
-passed in row number, and pass will always be 0. For the interlaced case the
-same applies unless the row value is 0, in which case the row just handled was
-the last one from one of the preceding passes. Because interlacing may skip a
-pass you cannot be sure that the preceding pass is just 'pass\-1', if you really
-need to know what the last pass is record (row,pass) from the callback and use
-the last recorded value each time.
-
-As with the user transform you can find the output row using the
-PNG_ROW_FROM_PASS_ROW macro.
-
-You now have the option of modifying how the compression library will
-run. The following functions are mainly for testing, but may be useful
-in some cases, like if you need to write PNG files extremely fast and
-are willing to give up some compression, or if you want to get the
-maximum possible compression at the expense of slower writing. If you
-have no special needs in this area, let the library do what it wants by
-not calling this function at all, as it has been tuned to deliver a good
-speed/compression ratio. The second parameter to png_set_filter() is
-the filter method, for which the only valid values are 0 (as of the
-July 1999 PNG specification, version 1.2) or 64 (if you are writing
-a PNG datastream that is to be embedded in a MNG datastream). The third
-parameter is a flag that indicates which filter type(s) are to be tested
-for each scanline. See the PNG specification for details on the specific
-filter types.
-
-
- /* turn on or off filtering, and/or choose
- specific filters. You can use either a single
- PNG_FILTER_VALUE_NAME or the bitwise OR of one
- or more PNG_FILTER_NAME masks.
- */
- png_set_filter(png_ptr, 0,
- PNG_FILTER_NONE | PNG_FILTER_VALUE_NONE |
- PNG_FILTER_SUB | PNG_FILTER_VALUE_SUB |
- PNG_FILTER_UP | PNG_FILTER_VALUE_UP |
- PNG_FILTER_AVG | PNG_FILTER_VALUE_AVG |
- PNG_FILTER_PAETH | PNG_FILTER_VALUE_PAETH|
- PNG_ALL_FILTERS | PNG_FAST_FILTERS);
-
-If an application wants to start and stop using particular filters during
-compression, it should start out with all of the filters (to ensure that
-the previous row of pixels will be stored in case it's needed later),
-and then add and remove them after the start of compression.
-
-If you are writing a PNG datastream that is to be embedded in a MNG
-datastream, the second parameter can be either 0 or 64.
-
-The png_set_compression_*() functions interface to the zlib compression
-library, and should mostly be ignored unless you really know what you are
-doing. The only generally useful call is png_set_compression_level()
-which changes how much time zlib spends on trying to compress the image
-data. See the Compression Library (zlib.h and algorithm.txt, distributed
-with zlib) for details on the compression levels.
-
- #include zlib.h
-
- /* Set the zlib compression level */
- png_set_compression_level(png_ptr,
- Z_BEST_COMPRESSION);
-
- /* Set other zlib parameters for compressing IDAT */
- png_set_compression_mem_level(png_ptr, 8);
- png_set_compression_strategy(png_ptr,
- Z_DEFAULT_STRATEGY);
- png_set_compression_window_bits(png_ptr, 15);
- png_set_compression_method(png_ptr, 8);
- png_set_compression_buffer_size(png_ptr, 8192)
-
- /* Set zlib parameters for text compression
- * If you don't call these, the parameters
- * fall back on those defined for IDAT chunks
- */
- png_set_text_compression_mem_level(png_ptr, 8);
- png_set_text_compression_strategy(png_ptr,
- Z_DEFAULT_STRATEGY);
- png_set_text_compression_window_bits(png_ptr, 15);
- png_set_text_compression_method(png_ptr, 8);
-
-.SS Setting the contents of info for output
-
-You now need to fill in the png_info structure with all the data you
-wish to write before the actual image. Note that the only thing you
-are allowed to write after the image is the text chunks and the time
-chunk (as of PNG Specification 1.2, anyway). See png_write_end() and
-the latest PNG specification for more information on that. If you
-wish to write them before the image, fill them in now, and flag that
-data as being valid. If you want to wait until after the data, don't
-fill them until png_write_end(). For all the fields in png_info and
-their data types, see png.h. For explanations of what the fields
-contain, see the PNG specification.
-
-Some of the more important parts of the png_info are:
-
- png_set_IHDR(png_ptr, info_ptr, width, height,
- bit_depth, color_type, interlace_type,
- compression_type, filter_method)
-
- width - holds the width of the image
- in pixels (up to 2^31).
-
- height - holds the height of the image
- in pixels (up to 2^31).
-
- bit_depth - holds the bit depth of one of the
- image channels.
- (valid values are 1, 2, 4, 8, 16
- and depend also on the
- color_type. See also significant
- bits (sBIT) below).
-
- color_type - describes which color/alpha
- channels are present.
- PNG_COLOR_TYPE_GRAY
- (bit depths 1, 2, 4, 8, 16)
- PNG_COLOR_TYPE_GRAY_ALPHA
- (bit depths 8, 16)
- PNG_COLOR_TYPE_PALETTE
- (bit depths 1, 2, 4, 8)
- PNG_COLOR_TYPE_RGB
- (bit_depths 8, 16)
- PNG_COLOR_TYPE_RGB_ALPHA
- (bit_depths 8, 16)
-
- PNG_COLOR_MASK_PALETTE
- PNG_COLOR_MASK_COLOR
- PNG_COLOR_MASK_ALPHA
-
- interlace_type - PNG_INTERLACE_NONE or
- PNG_INTERLACE_ADAM7
-
- compression_type - (must be
- PNG_COMPRESSION_TYPE_DEFAULT)
-
- filter_method - (must be PNG_FILTER_TYPE_DEFAULT
- or, if you are writing a PNG to
- be embedded in a MNG datastream,
- can also be
- PNG_INTRAPIXEL_DIFFERENCING)
-
-If you call png_set_IHDR(), the call must appear before any of the
-other png_set_*() functions, because they might require access to some of
-the IHDR settings. The remaining png_set_*() functions can be called
-in any order.
-
-If you wish, you can reset the compression_type, interlace_type, or
-filter_method later by calling png_set_IHDR() again; if you do this, the
-width, height, bit_depth, and color_type must be the same in each call.
-
- png_set_PLTE(png_ptr, info_ptr, palette,
- num_palette);
-
- palette - the palette for the file
- (array of png_color)
- num_palette - number of entries in the palette
-
-
- png_set_gAMA(png_ptr, info_ptr, file_gamma);
- png_set_gAMA_fixed(png_ptr, info_ptr, int_file_gamma);
-
- file_gamma - the gamma at which the image was
- created (PNG_INFO_gAMA)
-
- int_file_gamma - 100,000 times the gamma at which
- the image was created
-
- png_set_cHRM(png_ptr, info_ptr, white_x, white_y, red_x, red_y,
- green_x, green_y, blue_x, blue_y)
- png_set_cHRM_XYZ(png_ptr, info_ptr, red_X, red_Y, red_Z, green_X,
- green_Y, green_Z, blue_X, blue_Y, blue_Z)
- png_set_cHRM_fixed(png_ptr, info_ptr, int_white_x, int_white_y,
- int_red_x, int_red_y, int_green_x, int_green_y,
- int_blue_x, int_blue_y)
- png_set_cHRM_XYZ_fixed(png_ptr, info_ptr, int_red_X, int_red_Y,
- int_red_Z, int_green_X, int_green_Y, int_green_Z,
- int_blue_X, int_blue_Y, int_blue_Z)
-
- {white,red,green,blue}_{x,y}
- A color space encoding specified using the chromaticities
- of the end points and the white point.
-
- {red,green,blue}_{X,Y,Z}
- A color space encoding specified using the encoding end
- points - the CIE tristimulus specification of the intended
- color of the red, green and blue channels in the PNG RGB
- data. The white point is simply the sum of the three end
- points.
-
- png_set_sRGB(png_ptr, info_ptr, srgb_intent);
-
- srgb_intent - the rendering intent
- (PNG_INFO_sRGB) The presence of
- the sRGB chunk means that the pixel
- data is in the sRGB color space.
- This chunk also implies specific
- values of gAMA and cHRM. Rendering
- intent is the CSS-1 property that
- has been defined by the International
- Color Consortium
- (http://www.color.org).
- It can be one of
- PNG_sRGB_INTENT_SATURATION,
- PNG_sRGB_INTENT_PERCEPTUAL,
- PNG_sRGB_INTENT_ABSOLUTE, or
- PNG_sRGB_INTENT_RELATIVE.
-
-
- png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr,
- srgb_intent);
-
- srgb_intent - the rendering intent
- (PNG_INFO_sRGB) The presence of the
- sRGB chunk means that the pixel
- data is in the sRGB color space.
- This function also causes gAMA and
- cHRM chunks with the specific values
- that are consistent with sRGB to be
- written.
-
- png_set_iCCP(png_ptr, info_ptr, name, compression_type,
- profile, proflen);
-
- name - The profile name.
-
- compression_type - The compression type; always
- PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
- You may give NULL to this argument to
- ignore it.
-
- profile - International Color Consortium color
- profile data. May contain NULs.
-
- proflen - length of profile data in bytes.
-
- png_set_sBIT(png_ptr, info_ptr, sig_bit);
-
- sig_bit - the number of significant bits for
- (PNG_INFO_sBIT) each of the gray, red,
- green, and blue channels, whichever are
- appropriate for the given color type
- (png_color_16)
-
- png_set_tRNS(png_ptr, info_ptr, trans_alpha,
- num_trans, trans_color);
-
- trans_alpha - array of alpha (transparency)
- entries for palette (PNG_INFO_tRNS)
-
- num_trans - number of transparent entries
- (PNG_INFO_tRNS)
-
- trans_color - graylevel or color sample values
- (in order red, green, blue) of the
- single transparent color for
- non-paletted images (PNG_INFO_tRNS)
-
- png_set_eXIf(png_ptr, info_ptr, exif);
-
- hist - Exif profile (array of
- png_byte) (PNG_INFO_eXIf)
-
- png_set_hIST(png_ptr, info_ptr, hist);
-
- hist - histogram of palette (array of
- png_uint_16) (PNG_INFO_hIST)
-
- png_set_tIME(png_ptr, info_ptr, mod_time);
-
- mod_time - time image was last modified
- (PNG_VALID_tIME)
-
- png_set_bKGD(png_ptr, info_ptr, background);
-
- background - background color (of type
- png_color_16p) (PNG_VALID_bKGD)
-
- png_set_text(png_ptr, info_ptr, text_ptr, num_text);
-
- text_ptr - array of png_text holding image
- comments
-
- text_ptr[i].compression - type of compression used
- on "text" PNG_TEXT_COMPRESSION_NONE
- PNG_TEXT_COMPRESSION_zTXt
- PNG_ITXT_COMPRESSION_NONE
- PNG_ITXT_COMPRESSION_zTXt
- text_ptr[i].key - keyword for comment. Must contain
- 1-79 characters.
- text_ptr[i].text - text comments for current
- keyword. Can be NULL or empty.
- text_ptr[i].text_length - length of text string,
- after decompression, 0 for iTXt
- text_ptr[i].itxt_length - length of itxt string,
- after decompression, 0 for tEXt/zTXt
- text_ptr[i].lang - language of comment (NULL or
- empty for unknown).
- text_ptr[i].translated_keyword - keyword in UTF-8 (NULL
- or empty for unknown).
-
- Note that the itxt_length, lang, and lang_key
- members of the text_ptr structure only exist when the
- library is built with iTXt chunk support. Prior to
- libpng-1.4.0 the library was built by default without
- iTXt support. Also note that when iTXt is supported,
- they contain NULL pointers when the "compression"
- field contains PNG_TEXT_COMPRESSION_NONE or
- PNG_TEXT_COMPRESSION_zTXt.
-
- num_text - number of comments
-
- png_set_sPLT(png_ptr, info_ptr, &palette_ptr,
- num_spalettes);
-
- palette_ptr - array of png_sPLT_struct structures
- to be added to the list of palettes
- in the info structure.
- num_spalettes - number of palette structures to be
- added.
-
- png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y,
- unit_type);
-
- offset_x - positive offset from the left
- edge of the screen
-
- offset_y - positive offset from the top
- edge of the screen
-
- unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
-
- png_set_pHYs(png_ptr, info_ptr, res_x, res_y,
- unit_type);
-
- res_x - pixels/unit physical resolution
- in x direction
-
- res_y - pixels/unit physical resolution
- in y direction
-
- unit_type - PNG_RESOLUTION_UNKNOWN,
- PNG_RESOLUTION_METER
-
- png_set_sCAL(png_ptr, info_ptr, unit, width, height)
-
- unit - physical scale units (an integer)
-
- width - width of a pixel in physical scale units
-
- height - height of a pixel in physical scale units
- (width and height are doubles)
-
- png_set_sCAL_s(png_ptr, info_ptr, unit, width, height)
-
- unit - physical scale units (an integer)
-
- width - width of a pixel in physical scale units
- expressed as a string
-
- height - height of a pixel in physical scale units
- (width and height are strings like "2.54")
-
- png_set_unknown_chunks(png_ptr, info_ptr, &unknowns,
- num_unknowns)
-
- unknowns - array of png_unknown_chunk
- structures holding unknown chunks
- unknowns[i].name - name of unknown chunk
- unknowns[i].data - data of unknown chunk
- unknowns[i].size - size of unknown chunk's data
- unknowns[i].location - position to write chunk in file
- 0: do not write chunk
- PNG_HAVE_IHDR: before PLTE
- PNG_HAVE_PLTE: before IDAT
- PNG_AFTER_IDAT: after IDAT
-
-The "location" member is set automatically according to
-what part of the output file has already been written.
-You can change its value after calling png_set_unknown_chunks()
-as demonstrated in pngtest.c. Within each of the "locations",
-the chunks are sequenced according to their position in the
-structure (that is, the value of "i", which is the order in which
-the chunk was either read from the input file or defined with
-png_set_unknown_chunks).
-
-A quick word about text and num_text. text is an array of png_text
-structures. num_text is the number of valid structures in the array.
-Each png_text structure holds a language code, a keyword, a text value,
-and a compression type.
-
-The compression types have the same valid numbers as the compression
-types of the image data. Currently, the only valid number is zero.
-However, you can store text either compressed or uncompressed, unlike
-images, which always have to be compressed. So if you don't want the
-text compressed, set the compression type to PNG_TEXT_COMPRESSION_NONE.
-Because tEXt and zTXt chunks don't have a language field, if you
-specify PNG_TEXT_COMPRESSION_NONE or PNG_TEXT_COMPRESSION_zTXt
-any language code or translated keyword will not be written out.
-
-Until text gets around a few hundred bytes, it is not worth compressing it.
-After the text has been written out to the file, the compression type
-is set to PNG_TEXT_COMPRESSION_NONE_WR or PNG_TEXT_COMPRESSION_zTXt_WR,
-so that it isn't written out again at the end (in case you are calling
-png_write_end() with the same struct).
-
-The keywords that are given in the PNG Specification are:
-
- Title Short (one line) title or
- caption for image
-
- Author Name of image's creator
-
- Description Description of image (possibly long)
-
- Copyright Copyright notice
-
- Creation Time Time of original image creation
- (usually RFC 1123 format, see below)
-
- Software Software used to create the image
-
- Disclaimer Legal disclaimer
-
- Warning Warning of nature of content
-
- Source Device used to create the image
-
- Comment Miscellaneous comment; conversion
- from other image format
-
-The keyword-text pairs work like this. Keywords should be short
-simple descriptions of what the comment is about. Some typical
-keywords are found in the PNG specification, as is some recommendations
-on keywords. You can repeat keywords in a file. You can even write
-some text before the image and some after. For example, you may want
-to put a description of the image before the image, but leave the
-disclaimer until after, so viewers working over modem connections
-don't have to wait for the disclaimer to go over the modem before
-they start seeing the image. Finally, keywords should be full
-words, not abbreviations. Keywords and text are in the ISO 8859-1
-(Latin-1) character set (a superset of regular ASCII) and can not
-contain NUL characters, and should not contain control or other
-unprintable characters. To make the comments widely readable, stick
-with basic ASCII, and avoid machine specific character set extensions
-like the IBM-PC character set. The keyword must be present, but
-you can leave off the text string on non-compressed pairs.
-Compressed pairs must have a text string, as only the text string
-is compressed anyway, so the compression would be meaningless.
-
-PNG supports modification time via the png_time structure. Two
-conversion routines are provided, png_convert_from_time_t() for
-time_t and png_convert_from_struct_tm() for struct tm. The
-time_t routine uses gmtime(). You don't have to use either of
-these, but if you wish to fill in the png_time structure directly,
-you should provide the time in universal time (GMT) if possible
-instead of your local time. Note that the year number is the full
-year (e.g. 1998, rather than 98 - PNG is year 2000 compliant!), and
-that months start with 1.
-
-If you want to store the time of the original image creation, you should
-use a plain tEXt chunk with the "Creation Time" keyword. This is
-necessary because the "creation time" of a PNG image is somewhat vague,
-depending on whether you mean the PNG file, the time the image was
-created in a non-PNG format, a still photo from which the image was
-scanned, or possibly the subject matter itself. In order to facilitate
-machine-readable dates, it is recommended that the "Creation Time"
-tEXt chunk use RFC 1123 format dates (e.g. "22 May 1997 18:07:10 GMT"),
-although this isn't a requirement. Unlike the tIME chunk, the
-"Creation Time" tEXt chunk is not expected to be automatically changed
-by the software. To facilitate the use of RFC 1123 dates, a function
-png_convert_to_rfc1123_buffer(buffer, png_timep) is provided to
-convert from PNG time to an RFC 1123 format string. The caller must provide
-a writeable buffer of at least 29 bytes.
-
-.SS Writing unknown chunks
-
-You can use the png_set_unknown_chunks function to queue up private chunks
-for writing. You give it a chunk name, location, raw data, and a size. You
-also must use png_set_keep_unknown_chunks() to ensure that libpng will
-handle them. That's all there is to it. The chunks will be written by the
-next following png_write_info_before_PLTE, png_write_info, or png_write_end
-function, depending upon the specified location. Any chunks previously
-read into the info structure's unknown-chunk list will also be written out
-in a sequence that satisfies the PNG specification's ordering rules.
-
-Here is an example of writing two private chunks, prVt and miNE:
-
- #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
- /* Set unknown chunk data */
- png_unknown_chunk unk_chunk[2];
- strcpy((char *) unk_chunk[0].name, "prVt";
- unk_chunk[0].data = (unsigned char *) "PRIVATE DATA";
- unk_chunk[0].size = strlen(unk_chunk[0].data)+1;
- unk_chunk[0].location = PNG_HAVE_IHDR;
- strcpy((char *) unk_chunk[1].name, "miNE";
- unk_chunk[1].data = (unsigned char *) "MY CHUNK DATA";
- unk_chunk[1].size = strlen(unk_chunk[0].data)+1;
- unk_chunk[1].location = PNG_AFTER_IDAT;
- png_set_unknown_chunks(write_ptr, write_info_ptr,
- unk_chunk, 2);
- /* Needed because miNE is not safe-to-copy */
- png_set_keep_unknown_chunks(png, PNG_HANDLE_CHUNK_ALWAYS,
- (png_bytep) "miNE", 1);
- # if PNG_LIBPNG_VER < 10600
- /* Deal with unknown chunk location bug in 1.5.x and earlier */
- png_set_unknown_chunk_location(png, info, 0, PNG_HAVE_IHDR);
- png_set_unknown_chunk_location(png, info, 1, PNG_AFTER_IDAT);
- # endif
- # if PNG_LIBPNG_VER < 10500
- /* PNG_AFTER_IDAT writes two copies of the chunk prior to libpng-1.5.0,
- * one before IDAT and another after IDAT, so don't use it; only use
- * PNG_HAVE_IHDR location. This call resets the location previously
- * set by assignment and png_set_unknown_chunk_location() for chunk 1.
- */
- png_set_unknown_chunk_location(png, info, 1, PNG_HAVE_IHDR);
- # endif
- #endif
-
-.SS The high-level write interface
-
-At this point there are two ways to proceed; through the high-level
-write interface, or through a sequence of low-level write operations.
-You can use the high-level interface if your image data is present
-in the info structure. All defined output
-transformations are permitted, enabled by the following masks.
-
- PNG_TRANSFORM_IDENTITY No transformation
- PNG_TRANSFORM_PACKING Pack 1, 2 and 4-bit samples
- PNG_TRANSFORM_PACKSWAP Change order of packed
- pixels to LSB first
- PNG_TRANSFORM_INVERT_MONO Invert monochrome images
- PNG_TRANSFORM_SHIFT Normalize pixels to the
- sBIT depth
- PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA
- to BGRA
- PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA
- to AG
- PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
- to transparency
- PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
- PNG_TRANSFORM_STRIP_FILLER Strip out filler
- bytes (deprecated).
- PNG_TRANSFORM_STRIP_FILLER_BEFORE Strip out leading
- filler bytes
- PNG_TRANSFORM_STRIP_FILLER_AFTER Strip out trailing
- filler bytes
-
-If you have valid image data in the info structure (you can use
-png_set_rows() to put image data in the info structure), simply do this:
-
- png_write_png(png_ptr, info_ptr, png_transforms, NULL)
-
-where png_transforms is an integer containing the bitwise OR of some set of
-transformation flags. This call is equivalent to png_write_info(),
-followed the set of transformations indicated by the transform mask,
-then png_write_image(), and finally png_write_end().
-
-(The final parameter of this call is not yet used. Someday it might point
-to transformation parameters required by some future output transform.)
-
-You must use png_transforms and not call any png_set_transform() functions
-when you use png_write_png().
-
-.SS The low-level write interface
-
-If you are going the low-level route instead, you are now ready to
-write all the file information up to the actual image data. You do
-this with a call to png_write_info().
-
- png_write_info(png_ptr, info_ptr);
-
-Note that there is one transformation you may need to do before
-png_write_info(). In PNG files, the alpha channel in an image is the
-level of opacity. If your data is supplied as a level of transparency,
-you can invert the alpha channel before you write it, so that 0 is
-fully transparent and 255 (in 8-bit or paletted images) or 65535
-(in 16-bit images) is fully opaque, with
-
- png_set_invert_alpha(png_ptr);
-
-This must appear before png_write_info() instead of later with the
-other transformations because in the case of paletted images the tRNS
-chunk data has to be inverted before the tRNS chunk is written. If
-your image is not a paletted image, the tRNS data (which in such cases
-represents a single color to be rendered as transparent) won't need to
-be changed, and you can safely do this transformation after your
-png_write_info() call.
-
-If you need to write a private chunk that you want to appear before
-the PLTE chunk when PLTE is present, you can write the PNG info in
-two steps, and insert code to write your own chunk between them:
-
- png_write_info_before_PLTE(png_ptr, info_ptr);
- png_set_unknown_chunks(png_ptr, info_ptr, ...);
- png_write_info(png_ptr, info_ptr);
-
-After you've written the file information, you can set up the library
-to handle any special transformations of the image data. The various
-ways to transform the data will be described in the order that they
-should occur. This is important, as some of these change the color
-type and/or bit depth of the data, and some others only work on
-certain color types and bit depths. Even though each transformation
-checks to see if it has data that it can do something with, you should
-make sure to only enable a transformation if it will be valid for the
-data. For example, don't swap red and blue on grayscale data.
-
-PNG files store RGB pixels packed into 3 or 6 bytes. This code tells
-the library to strip input data that has 4 or 8 bytes per pixel down
-to 3 or 6 bytes (or strip 2 or 4-byte grayscale+filler data to 1 or 2
-bytes per pixel).
-
- png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
-
-where the 0 is unused, and the location is either PNG_FILLER_BEFORE or
-PNG_FILLER_AFTER, depending upon whether the filler byte in the pixel
-is stored XRGB or RGBX.
-
-PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
-they can, resulting in, for example, 8 pixels per byte for 1 bit files.
-If the data is supplied at 1 pixel per byte, use this code, which will
-correctly pack the pixels into a single byte:
-
- png_set_packing(png_ptr);
-
-PNG files reduce possible bit depths to 1, 2, 4, 8, and 16. If your
-data is of another bit depth, you can write an sBIT chunk into the
-file so that decoders can recover the original data if desired.
-
- /* Set the true bit depth of the image data */
- if (color_type & PNG_COLOR_MASK_COLOR)
- {
- sig_bit.red = true_bit_depth;
- sig_bit.green = true_bit_depth;
- sig_bit.blue = true_bit_depth;
- }
-
- else
- {
- sig_bit.gray = true_bit_depth;
- }
-
- if (color_type & PNG_COLOR_MASK_ALPHA)
- {
- sig_bit.alpha = true_bit_depth;
- }
-
- png_set_sBIT(png_ptr, info_ptr, &sig_bit);
-
-If the data is stored in the row buffer in a bit depth other than
-one supported by PNG (e.g. 3 bit data in the range 0-7 for a 4-bit PNG),
-this will scale the values to appear to be the correct bit depth as
-is required by PNG.
-
- png_set_shift(png_ptr, &sig_bit);
-
-PNG files store 16-bit pixels in network byte order (big-endian,
-ie. most significant bits first). This code would be used if they are
-supplied the other way (little-endian, i.e. least significant bits
-first, the way PCs store them):
-
- if (bit_depth > 8)
- png_set_swap(png_ptr);
-
-If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
-need to change the order the pixels are packed into bytes, you can use:
-
- if (bit_depth < 8)
- png_set_packswap(png_ptr);
-
-PNG files store 3 color pixels in red, green, blue order. This code
-would be used if they are supplied as blue, green, red:
-
- png_set_bgr(png_ptr);
-
-PNG files describe monochrome as black being zero and white being
-one. This code would be used if the pixels are supplied with this reversed
-(black being one and white being zero):
-
- png_set_invert_mono(png_ptr);
-
-Finally, you can write your own transformation function if none of
-the existing ones meets your needs. This is done by setting a callback
-with
-
- png_set_write_user_transform_fn(png_ptr,
- write_transform_fn);
-
-You must supply the function
-
- void write_transform_fn(png_structp png_ptr, png_row_infop
- row_info, png_bytep data)
-
-See pngtest.c for a working example. Your function will be called
-before any of the other transformations are processed. If supported
-libpng also supplies an information routine that may be called from
-your callback:
-
- png_get_current_row_number(png_ptr);
- png_get_current_pass_number(png_ptr);
-
-This returns the current row passed to the transform. With interlaced
-images the value returned is the row in the input sub-image image. Use
-PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
-find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass).
-
-The discussion of interlace handling above contains more information on how to
-use these values.
-
-You can also set up a pointer to a user structure for use by your
-callback function.
-
- png_set_user_transform_info(png_ptr, user_ptr, 0, 0);
-
-The user_channels and user_depth parameters of this function are ignored
-when writing; you can set them to zero as shown.
-
-You can retrieve the pointer via the function png_get_user_transform_ptr().
-For example:
-
- voidp write_user_transform_ptr =
- png_get_user_transform_ptr(png_ptr);
-
-It is possible to have libpng flush any pending output, either manually,
-or automatically after a certain number of lines have been written. To
-flush the output stream a single time call:
-
- png_write_flush(png_ptr);
-
-and to have libpng flush the output stream periodically after a certain
-number of scanlines have been written, call:
-
- png_set_flush(png_ptr, nrows);
-
-Note that the distance between rows is from the last time png_write_flush()
-was called, or the first row of the image if it has never been called.
-So if you write 50 lines, and then png_set_flush 25, it will flush the
-output on the next scanline, and every 25 lines thereafter, unless
-png_write_flush() is called before 25 more lines have been written.
-If nrows is too small (less than about 10 lines for a 640 pixel wide
-RGB image) the image compression may decrease noticeably (although this
-may be acceptable for real-time applications). Infrequent flushing will
-only degrade the compression performance by a few percent over images
-that do not use flushing.
-
-.SS Writing the image data
-
-That's it for the transformations. Now you can write the image data.
-The simplest way to do this is in one function call. If you have the
-whole image in memory, you can just call png_write_image() and libpng
-will write the image. You will need to pass in an array of pointers to
-each row. This function automatically handles interlacing, so you don't
-need to call png_set_interlace_handling() or call this function multiple
-times, or any of that other stuff necessary with png_write_rows().
-
- png_write_image(png_ptr, row_pointers);
-
-where row_pointers is:
-
- png_byte *row_pointers[height];
-
-You can point to void or char or whatever you use for pixels.
-
-If you don't want to write the whole image at once, you can
-use png_write_rows() instead. If the file is not interlaced,
-this is simple:
-
- png_write_rows(png_ptr, row_pointers,
- number_of_rows);
-
-row_pointers is the same as in the png_write_image() call.
-
-If you are just writing one row at a time, you can do this with
-a single row_pointer instead of an array of row_pointers:
-
- png_bytep row_pointer = row;
-
- png_write_row(png_ptr, row_pointer);
-
-When the file is interlaced, things can get a good deal more complicated.
-The only currently (as of the PNG Specification version 1.2, dated July
-1999) defined interlacing scheme for PNG files is the "Adam7" interlace
-scheme, that breaks down an image into seven smaller images of varying
-size. libpng will build these images for you, or you can do them
-yourself. If you want to build them yourself, see the PNG specification
-for details of which pixels to write when.
-
-If you don't want libpng to handle the interlacing details, just
-use png_set_interlace_handling() and call png_write_rows() the
-correct number of times to write all the sub-images
-(png_set_interlace_handling() returns the number of sub-images.)
-
-If you want libpng to build the sub-images, call this before you start
-writing any rows:
-
- number_of_passes = png_set_interlace_handling(png_ptr);
-
-This will return the number of passes needed. Currently, this is seven,
-but may change if another interlace type is added.
-
-Then write the complete image number_of_passes times.
-
- png_write_rows(png_ptr, row_pointers, number_of_rows);
-
-Think carefully before you write an interlaced image. Typically code that
-reads such images reads all the image data into memory, uncompressed, before
-doing any processing. Only code that can display an image on the fly can
-take advantage of the interlacing and even then the image has to be exactly
-the correct size for the output device, because scaling an image requires
-adjacent pixels and these are not available until all the passes have been
-read.
-
-If you do write an interlaced image you will hardly ever need to handle
-the interlacing yourself. Call png_set_interlace_handling() and use the
-approach described above.
-
-The only time it is conceivable that you will really need to write an
-interlaced image pass-by-pass is when you have read one pass by pass and
-made some pixel-by-pixel transformation to it, as described in the read
-code above. In this case use the PNG_PASS_ROWS and PNG_PASS_COLS macros
-to determine the size of each sub-image in turn and simply write the rows
-you obtained from the read code.
-
-.SS Finishing a sequential write
-
-After you are finished writing the image, you should finish writing
-the file. If you are interested in writing comments or time, you should
-pass an appropriately filled png_info pointer. If you are not interested,
-you can pass NULL.
-
- png_write_end(png_ptr, info_ptr);
-
-When you are done, you can free all memory used by libpng like this:
-
- png_destroy_write_struct(&png_ptr, &info_ptr);
-
-It is also possible to individually free the info_ptr members that
-point to libpng-allocated storage with the following function:
-
- png_free_data(png_ptr, info_ptr, mask, seq)
-
- mask - identifies data to be freed, a mask
- containing the bitwise OR of one or
- more of
- PNG_FREE_PLTE, PNG_FREE_TRNS,
- PNG_FREE_HIST, PNG_FREE_ICCP,
- PNG_FREE_PCAL, PNG_FREE_ROWS,
- PNG_FREE_SCAL, PNG_FREE_SPLT,
- PNG_FREE_TEXT, PNG_FREE_UNKN,
- or simply PNG_FREE_ALL
-
- seq - sequence number of item to be freed
- (\-1 for all items)
-
-This function may be safely called when the relevant storage has
-already been freed, or has not yet been allocated, or was allocated
-by the user and not by libpng, and will in those cases do nothing.
-The "seq" parameter is ignored if only one item of the selected data
-type, such as PLTE, is allowed. If "seq" is not \-1, and multiple items
-are allowed for the data type identified in the mask, such as text or
-sPLT, only the n'th item in the structure is freed, where n is "seq".
-
-If you allocated data such as a palette that you passed in to libpng
-with png_set_*, you must not free it until just before the call to
-png_destroy_write_struct().
-
-The default behavior is only to free data that was allocated internally
-by libpng. This can be changed, so that libpng will not free the data,
-or so that it will free data that was allocated by the user with png_malloc()
-or png_calloc() and passed in via a png_set_*() function, with
-
- png_data_freer(png_ptr, info_ptr, freer, mask)
-
- freer - one of
- PNG_DESTROY_WILL_FREE_DATA
- PNG_SET_WILL_FREE_DATA
- PNG_USER_WILL_FREE_DATA
-
- mask - which data elements are affected
- same choices as in png_free_data()
-
-For example, to transfer responsibility for some data from a read structure
-to a write structure, you could use
-
- png_data_freer(read_ptr, read_info_ptr,
- PNG_USER_WILL_FREE_DATA,
- PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
-
- png_data_freer(write_ptr, write_info_ptr,
- PNG_DESTROY_WILL_FREE_DATA,
- PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
-
-thereby briefly reassigning responsibility for freeing to the user but
-immediately afterwards reassigning it once more to the write_destroy
-function. Having done this, it would then be safe to destroy the read
-structure and continue to use the PLTE, tRNS, and hIST data in the write
-structure.
-
-This function only affects data that has already been allocated.
-You can call this function before calling after the png_set_*() functions
-to control whether the user or png_destroy_*() is supposed to free the data.
-When the user assumes responsibility for libpng-allocated data, the
-application must use
-png_free() to free it, and when the user transfers responsibility to libpng
-for data that the user has allocated, the user must have used png_malloc()
-or png_calloc() to allocate it.
-
-If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
-separately, do not transfer responsibility for freeing text_ptr to libpng,
-because when libpng fills a png_text structure it combines these members with
-the key member, and png_free_data() will free only text_ptr.key. Similarly,
-if you transfer responsibility for free'ing text_ptr from libpng to your
-application, your application must not separately free those members.
-For a more compact example of writing a PNG image, see the file example.c.
-
-.SH V. Simplified API
-
-The simplified API, which became available in libpng-1.6.0, hides the details
-of both libpng and the PNG file format itself.
-It allows PNG files to be read into a very limited number of
-in-memory bitmap formats or to be written from the same formats. If these
-formats do not accommodate your needs then you can, and should, use the more
-sophisticated APIs above - these support a wide variety of in-memory formats
-and a wide variety of sophisticated transformations to those formats as well
-as a wide variety of APIs to manipulate ancilliary information.
-
-To read a PNG file using the simplified API:
-
- 1) Declare a 'png_image' structure (see below) on the stack, set the
- version field to PNG_IMAGE_VERSION and the 'opaque' pointer to NULL
- (this is REQUIRED, your program may crash if you don't do it.)
-
- 2) Call the appropriate png_image_begin_read... function.
-
- 3) Set the png_image 'format' member to the required sample format.
-
- 4) Allocate a buffer for the image and, if required, the color-map.
-
- 5) Call png_image_finish_read to read the image and, if required, the
- color-map into your buffers.
-
-There are no restrictions on the format of the PNG input itself; all valid
-color types, bit depths, and interlace methods are acceptable, and the
-input image is transformed as necessary to the requested in-memory format
-during the png_image_finish_read() step. The only caveat is that if you
-request a color-mapped image from a PNG that is full-color or makes
-complex use of an alpha channel the transformation is extremely lossy and the
-result may look terrible.
-
-To write a PNG file using the simplified API:
-
- 1) Declare a 'png_image' structure on the stack and memset()
- it to all zero.
-
- 2) Initialize the members of the structure that describe the
- image, setting the 'format' member to the format of the
- image samples.
-
- 3) Call the appropriate png_image_write... function with a
- pointer to the image and, if necessary, the color-map to write
- the PNG data.
-
-png_image is a structure that describes the in-memory format of an image
-when it is being read or defines the in-memory format of an image that you
-need to write. The "png_image" structure contains the following members:
-
- png_controlp opaque Initialize to NULL, free with png_image_free
- png_uint_32 version Set to PNG_IMAGE_VERSION
- png_uint_32 width Image width in pixels (columns)
- png_uint_32 height Image height in pixels (rows)
- png_uint_32 format Image format as defined below
- png_uint_32 flags A bit mask containing informational flags
- png_uint_32 colormap_entries; Number of entries in the color-map
- png_uint_32 warning_or_error;
- char message[64];
-
-In the event of an error or warning the "warning_or_error"
-field will be set to a non-zero value and the 'message' field will contain
-a '\0' terminated string with the libpng error or warning message. If both
-warnings and an error were encountered, only the error is recorded. If there
-are multiple warnings, only the first one is recorded.
-
-The upper 30 bits of the "warning_or_error" value are reserved; the low two
-bits contain a two bit code such that a value more than 1 indicates a failure
-in the API just called:
-
- 0 - no warning or error
- 1 - warning
- 2 - error
- 3 - error preceded by warning
-
-The pixels (samples) of the image have one to four channels whose components
-have original values in the range 0 to 1.0:
-
- 1: A single gray or luminance channel (G).
- 2: A gray/luminance channel and an alpha channel (GA).
- 3: Three red, green, blue color channels (RGB).
- 4: Three color channels and an alpha channel (RGBA).
-
-The channels are encoded in one of two ways:
-
- a) As a small integer, value 0..255, contained in a single byte. For the
-alpha channel the original value is simply value/255. For the color or
-luminance channels the value is encoded according to the sRGB specification
-and matches the 8-bit format expected by typical display devices.
-
-The color/gray channels are not scaled (pre-multiplied) by the alpha
-channel and are suitable for passing to color management software.
-
- b) As a value in the range 0..65535, contained in a 2-byte integer, in
-the native byte order of the platform on which the application is running.
-All channels can be converted to the original value by dividing by 65535; all
-channels are linear. Color channels use the RGB encoding (RGB end-points) of
-the sRGB specification. This encoding is identified by the
-PNG_FORMAT_FLAG_LINEAR flag below.
-
-When the simplified API needs to convert between sRGB and linear colorspaces,
-the actual sRGB transfer curve defined in the sRGB specification (see the
-article at https://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
-approximation used elsewhere in libpng.
-
-When an alpha channel is present it is expected to denote pixel coverage
-of the color or luminance channels and is returned as an associated alpha
-channel: the color/gray channels are scaled (pre-multiplied) by the alpha
-value.
-
-The samples are either contained directly in the image data, between 1 and 8
-bytes per pixel according to the encoding, or are held in a color-map indexed
-by bytes in the image data. In the case of a color-map the color-map entries
-are individual samples, encoded as above, and the image data has one byte per
-pixel to select the relevant sample from the color-map.
-
-PNG_FORMAT_*
-
-The #defines to be used in png_image::format. Each #define identifies a
-particular layout of channel data and, if present, alpha values. There are
-separate defines for each of the two component encodings.
-
-A format is built up using single bit flag values. All combinations are
-valid. Formats can be built up from the flag values or you can use one of
-the predefined values below. When testing formats always use the FORMAT_FLAG
-macros to test for individual features - future versions of the library may
-add new flags.
-
-When reading or writing color-mapped images the format should be set to the
-format of the entries in the color-map then png_image_{read,write}_colormap
-called to read or write the color-map and set the format correctly for the
-image data. Do not set the PNG_FORMAT_FLAG_COLORMAP bit directly!
-
-NOTE: libpng can be built with particular features disabled. If you see
-compiler errors because the definition of one of the following flags has been
-compiled out it is because libpng does not have the required support. It is
-possible, however, for the libpng configuration to enable the format on just
-read or just write; in that case you may see an error at run time.
-You can guard against this by checking for the definition of the
-appropriate "_SUPPORTED" macro, one of:
-
- PNG_SIMPLIFIED_{READ,WRITE}_{BGR,AFIRST}_SUPPORTED
-
- PNG_FORMAT_FLAG_ALPHA format with an alpha channel
- PNG_FORMAT_FLAG_COLOR color format: otherwise grayscale
- PNG_FORMAT_FLAG_LINEAR 2-byte channels else 1-byte
- PNG_FORMAT_FLAG_COLORMAP image data is color-mapped
- PNG_FORMAT_FLAG_BGR BGR colors, else order is RGB
- PNG_FORMAT_FLAG_AFIRST alpha channel comes first
-
-Supported formats are as follows. Future versions of libpng may support more
-formats; for compatibility with older versions simply check if the format
-macro is defined using #ifdef. These defines describe the in-memory layout
-of the components of the pixels of the image.
-
-First the single byte (sRGB) formats:
-
- PNG_FORMAT_GRAY
- PNG_FORMAT_GA
- PNG_FORMAT_AG
- PNG_FORMAT_RGB
- PNG_FORMAT_BGR
- PNG_FORMAT_RGBA
- PNG_FORMAT_ARGB
- PNG_FORMAT_BGRA
- PNG_FORMAT_ABGR
-
-Then the linear 2-byte formats. When naming these "Y" is used to
-indicate a luminance (gray) channel. The component order within the pixel
-is always the same - there is no provision for swapping the order of the
-components in the linear format. The components are 16-bit integers in
-the native byte order for your platform, and there is no provision for
-swapping the bytes to a different endian condition.
-
- PNG_FORMAT_LINEAR_Y
- PNG_FORMAT_LINEAR_Y_ALPHA
- PNG_FORMAT_LINEAR_RGB
- PNG_FORMAT_LINEAR_RGB_ALPHA
-
-With color-mapped formats the image data is one byte for each pixel. The byte
-is an index into the color-map which is formatted as above. To obtain a
-color-mapped format it is sufficient just to add the PNG_FOMAT_FLAG_COLORMAP
-to one of the above definitions, or you can use one of the definitions below.
-
- PNG_FORMAT_RGB_COLORMAP
- PNG_FORMAT_BGR_COLORMAP
- PNG_FORMAT_RGBA_COLORMAP
- PNG_FORMAT_ARGB_COLORMAP
- PNG_FORMAT_BGRA_COLORMAP
- PNG_FORMAT_ABGR_COLORMAP
-
-PNG_IMAGE macros
-
-These are convenience macros to derive information from a png_image
-structure. The PNG_IMAGE_SAMPLE_ macros return values appropriate to the
-actual image sample values - either the entries in the color-map or the
-pixels in the image. The PNG_IMAGE_PIXEL_ macros return corresponding values
-for the pixels and will always return 1 for color-mapped formats. The
-remaining macros return information about the rows in the image and the
-complete image.
-
-NOTE: All the macros that take a png_image::format parameter are compile time
-constants if the format parameter is, itself, a constant. Therefore these
-macros can be used in array declarations and case labels where required.
-Similarly the macros are also pre-processor constants (sizeof is not used) so
-they can be used in #if tests.
-
- PNG_IMAGE_SAMPLE_CHANNELS(fmt)
- Returns the total number of channels in a given format: 1..4
-
- PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt)
- Returns the size in bytes of a single component of a pixel or color-map
- entry (as appropriate) in the image: 1 or 2.
-
- PNG_IMAGE_SAMPLE_SIZE(fmt)
- This is the size of the sample data for one sample. If the image is
- color-mapped it is the size of one color-map entry (and image pixels are
- one byte in size), otherwise it is the size of one image pixel.
-
- PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(fmt)
- The maximum size of the color-map required by the format expressed in a
- count of components. This can be used to compile-time allocate a
- color-map:
-
- png_uint_16 colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(linear_fmt)];
-
- png_byte colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(sRGB_fmt)];
-
- Alternatively use the PNG_IMAGE_COLORMAP_SIZE macro below to use the
- information from one of the png_image_begin_read_ APIs and dynamically
- allocate the required memory.
-
- PNG_IMAGE_COLORMAP_SIZE(fmt)
- The size of the color-map required by the format; this is the size of the
- color-map buffer passed to the png_image_{read,write}_colormap APIs. It is
- a fixed number determined by the format so can easily be allocated on the
- stack if necessary.
-
-Corresponding information about the pixels
-
- PNG_IMAGE_PIXEL_CHANNELS(fmt)
- The number of separate channels (components) in a pixel; 1 for a
- color-mapped image.
-
- PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)\
- The size, in bytes, of each component in a pixel; 1 for a color-mapped
- image.
-
- PNG_IMAGE_PIXEL_SIZE(fmt)
- The size, in bytes, of a complete pixel; 1 for a color-mapped image.
-
-Information about the whole row, or whole image
-
- PNG_IMAGE_ROW_STRIDE(image)
- Returns the total number of components in a single row of the image; this
- is the minimum 'row stride', the minimum count of components between each
- row. For a color-mapped image this is the minimum number of bytes in a
- row.
-
- If you need the stride measured in bytes, row_stride_bytes is
- PNG_IMAGE_ROW_STRIDE(image) * PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)
- plus any padding bytes that your application might need, for example
- to start the next row on a 4-byte boundary.
-
- PNG_IMAGE_BUFFER_SIZE(image, row_stride)
- Return the size, in bytes, of an image buffer given a png_image and a row
- stride - the number of components to leave space for in each row.
-
- PNG_IMAGE_SIZE(image)
- Return the size, in bytes, of the image in memory given just a png_image;
- the row stride is the minimum stride required for the image.
-
- PNG_IMAGE_COLORMAP_SIZE(image)
- Return the size, in bytes, of the color-map of this image. If the image
- format is not a color-map format this will return a size sufficient for
- 256 entries in the given format; check PNG_FORMAT_FLAG_COLORMAP if
- you don't want to allocate a color-map in this case.
-
-PNG_IMAGE_FLAG_*
-
-Flags containing additional information about the image are held in
-the 'flags' field of png_image.
-
- PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB == 0x01
- This indicates the the RGB values of the in-memory bitmap do not
- correspond to the red, green and blue end-points defined by sRGB.
-
- PNG_IMAGE_FLAG_FAST == 0x02
- On write emphasise speed over compression; the resultant PNG file will be
- larger but will be produced significantly faster, particular for large
- images. Do not use this option for images which will be distributed, only
- used it when producing intermediate files that will be read back in
- repeatedly. For a typical 24-bit image the option will double the read
- speed at the cost of increasing the image size by 25%, however for many
- more compressible images the PNG file can be 10 times larger with only a
- slight speed gain.
-
- PNG_IMAGE_FLAG_16BIT_sRGB == 0x04
- On read if the image is a 16-bit per component image and there is no gAMA
- or sRGB chunk assume that the components are sRGB encoded. Notice that
- images output by the simplified API always have gamma information; setting
- this flag only affects the interpretation of 16-bit images from an
- external source. It is recommended that the application expose this flag
- to the user; the user can normally easily recognize the difference between
- linear and sRGB encoding. This flag has no effect on write - the data
- passed to the write APIs must have the correct encoding (as defined
- above.)
-
- If the flag is not set (the default) input 16-bit per component data is
- assumed to be linear.
-
- NOTE: the flag can only be set after the png_image_begin_read_ call,
- because that call initializes the 'flags' field.
-
-READ APIs
-
- The png_image passed to the read APIs must have been initialized by setting
- the png_controlp field 'opaque' to NULL (or, better, memset the whole thing.)
-
- int png_image_begin_read_from_file( png_imagep image,
- const char *file_name)
-
- The named file is opened for read and the image header
- is filled in from the PNG header in the file.
-
- int png_image_begin_read_from_stdio (png_imagep image,
- FILE* file)
-
- The PNG header is read from the stdio FILE object.
-
- int png_image_begin_read_from_memory(png_imagep image,
- png_const_voidp memory, png_size_t size)
-
- The PNG header is read from the given memory buffer.
-
- int png_image_finish_read(png_imagep image,
- png_colorp background, void *buffer,
- png_int_32 row_stride, void *colormap));
-
- Finish reading the image into the supplied buffer and
- clean up the png_image structure.
-
- row_stride is the step, in png_byte or png_uint_16 units
- as appropriate, between adjacent rows. A positive stride
- indicates that the top-most row is first in the buffer -
- the normal top-down arrangement. A negative stride
- indicates that the bottom-most row is first in the buffer.
-
- background need only be supplied if an alpha channel must
- be removed from a png_byte format and the removal is to be
- done by compositing on a solid color; otherwise it may be
- NULL and any composition will be done directly onto the
- buffer. The value is an sRGB color to use for the
- background, for grayscale output the green channel is used.
-
- For linear output removing the alpha channel is always done
- by compositing on black.
-
- void png_image_free(png_imagep image)
-
- Free any data allocated by libpng in image->opaque,
- setting the pointer to NULL. May be called at any time
- after the structure is initialized.
-
-When the simplified API needs to convert between sRGB and linear colorspaces,
-the actual sRGB transfer curve defined in the sRGB specification (see the
-article at https://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
-approximation used elsewhere in libpng.
-
-WRITE APIS
-
-For write you must initialize a png_image structure to describe the image to
-be written:
-
- version: must be set to PNG_IMAGE_VERSION
- opaque: must be initialized to NULL
- width: image width in pixels
- height: image height in rows
- format: the format of the data you wish to write
- flags: set to 0 unless one of the defined flags applies; set
- PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB for color format images
- where the RGB values do not correspond to the colors in sRGB.
- colormap_entries: set to the number of entries in the color-map (0 to 256)
-
- int png_image_write_to_file, (png_imagep image,
- const char *file, int convert_to_8bit, const void *buffer,
- png_int_32 row_stride, const void *colormap));
-
- Write the image to the named file.
-
- int png_image_write_to_memory (png_imagep image, void *memory,
- png_alloc_size_t * PNG_RESTRICT memory_bytes,
- int convert_to_8_bit, const void *buffer, ptrdiff_t row_stride,
- const void *colormap));
-
- Write the image to memory.
-
- int png_image_write_to_stdio(png_imagep image, FILE *file,
- int convert_to_8_bit, const void *buffer,
- png_int_32 row_stride, const void *colormap)
-
- Write the image to the given (FILE*).
-
-With all write APIs if image is in one of the linear formats with
-(png_uint_16) data then setting convert_to_8_bit will cause the output to be
-a (png_byte) PNG gamma encoded according to the sRGB specification, otherwise
-a 16-bit linear encoded PNG file is written.
-
-With all APIs row_stride is handled as in the read APIs - it is the spacing
-from one row to the next in component sized units (float) and if negative
-indicates a bottom-up row layout in the buffer. If you pass zero, libpng will
-calculate the row_stride for you from the width and number of channels.
-
-Note that the write API does not support interlacing, sub-8-bit pixels,
-indexed (paletted) images, or most ancillary chunks.
-
-.SH VI. Modifying/Customizing libpng
-
-There are two issues here. The first is changing how libpng does
-standard things like memory allocation, input/output, and error handling.
-The second deals with more complicated things like adding new chunks,
-adding new transformations, and generally changing how libpng works.
-Both of those are compile-time issues; that is, they are generally
-determined at the time the code is written, and there is rarely a need
-to provide the user with a means of changing them.
-
-Memory allocation, input/output, and error handling
-
-All of the memory allocation, input/output, and error handling in libpng
-goes through callbacks that are user-settable. The default routines are
-in pngmem.c, pngrio.c, pngwio.c, and pngerror.c, respectively. To change
-these functions, call the appropriate png_set_*_fn() function.
-
-Memory allocation is done through the functions png_malloc(), png_calloc(),
-and png_free(). The png_malloc() and png_free() functions currently just
-call the standard C functions and png_calloc() calls png_malloc() and then
-clears the newly allocated memory to zero; note that png_calloc(png_ptr, size)
-is not the same as the calloc(number, size) function provided by stdlib.h.
-There is limited support for certain systems with segmented memory
-architectures and the types of pointers declared by png.h match this; you
-will have to use appropriate pointers in your application. If you prefer
-to use a different method of allocating and freeing data, you can use
-png_create_read_struct_2() or png_create_write_struct_2() to register your
-own functions as described above. These functions also provide a void
-pointer that can be retrieved via
-
- mem_ptr=png_get_mem_ptr(png_ptr);
-
-Your replacement memory functions must have prototypes as follows:
-
- png_voidp malloc_fn(png_structp png_ptr,
- png_alloc_size_t size);
-
- void free_fn(png_structp png_ptr, png_voidp ptr);
-
-Your malloc_fn() must return NULL in case of failure. The png_malloc()
-function will normally call png_error() if it receives a NULL from the
-system memory allocator or from your replacement malloc_fn().
-
-Your free_fn() will never be called with a NULL ptr, since libpng's
-png_free() checks for NULL before calling free_fn().
-
-Input/Output in libpng is done through png_read() and png_write(),
-which currently just call fread() and fwrite(). The FILE * is stored in
-png_struct and is initialized via png_init_io(). If you wish to change
-the method of I/O, the library supplies callbacks that you can set
-through the function png_set_read_fn() and png_set_write_fn() at run
-time, instead of calling the png_init_io() function. These functions
-also provide a void pointer that can be retrieved via the function
-png_get_io_ptr(). For example:
-
- png_set_read_fn(png_structp read_ptr,
- voidp read_io_ptr, png_rw_ptr read_data_fn)
-
- png_set_write_fn(png_structp write_ptr,
- voidp write_io_ptr, png_rw_ptr write_data_fn,
- png_flush_ptr output_flush_fn);
-
- voidp read_io_ptr = png_get_io_ptr(read_ptr);
- voidp write_io_ptr = png_get_io_ptr(write_ptr);
-
-The replacement I/O functions must have prototypes as follows:
-
- void user_read_data(png_structp png_ptr,
- png_bytep data, png_size_t length);
-
- void user_write_data(png_structp png_ptr,
- png_bytep data, png_size_t length);
-
- void user_flush_data(png_structp png_ptr);
-
-The user_read_data() function is responsible for detecting and
-handling end-of-data errors.
-
-Supplying NULL for the read, write, or flush functions sets them back
-to using the default C stream functions, which expect the io_ptr to
-point to a standard *FILE structure. It is probably a mistake
-to use NULL for one of write_data_fn and output_flush_fn but not both
-of them, unless you have built libpng with PNG_NO_WRITE_FLUSH defined.
-It is an error to read from a write stream, and vice versa.
-
-Error handling in libpng is done through png_error() and png_warning().
-Errors handled through png_error() are fatal, meaning that png_error()
-should never return to its caller. Currently, this is handled via
-setjmp() and longjmp() (unless you have compiled libpng with
-PNG_NO_SETJMP, in which case it is handled via PNG_ABORT()),
-but you could change this to do things like exit() if you should wish,
-as long as your function does not return.
-
-On non-fatal errors, png_warning() is called
-to print a warning message, and then control returns to the calling code.
-By default png_error() and png_warning() print a message on stderr via
-fprintf() unless the library is compiled with PNG_NO_CONSOLE_IO defined
-(because you don't want the messages) or PNG_NO_STDIO defined (because
-fprintf() isn't available). If you wish to change the behavior of the error
-functions, you will need to set up your own message callbacks. These
-functions are normally supplied at the time that the png_struct is created.
-It is also possible to redirect errors and warnings to your own replacement
-functions after png_create_*_struct() has been called by calling:
-
- png_set_error_fn(png_structp png_ptr,
- png_voidp error_ptr, png_error_ptr error_fn,
- png_error_ptr warning_fn);
-
-If NULL is supplied for either error_fn or warning_fn, then the libpng
-default function will be used, calling fprintf() and/or longjmp() if a
-problem is encountered. The replacement error functions should have
-parameters as follows:
-
- void user_error_fn(png_structp png_ptr,
- png_const_charp error_msg);
-
- void user_warning_fn(png_structp png_ptr,
- png_const_charp warning_msg);
-
-Then, within your user_error_fn or user_warning_fn, you can retrieve
-the error_ptr if you need it, by calling
-
- png_voidp error_ptr = png_get_error_ptr(png_ptr);
-
-The motivation behind using setjmp() and longjmp() is the C++ throw and
-catch exception handling methods. This makes the code much easier to write,
-as there is no need to check every return code of every function call.
-However, there are some uncertainties about the status of local variables
-after a longjmp, so the user may want to be careful about doing anything
-after setjmp returns non-zero besides returning itself. Consult your
-compiler documentation for more details. For an alternative approach, you
-may wish to use the "cexcept" facility (see https://cexcept.sourceforge.io/),
-which is illustrated in pngvalid.c and in contrib/visupng.
-
-Beginning in libpng-1.4.0, the png_set_benign_errors() API became available.
-You can use this to handle certain errors (normally handled as errors)
-as warnings.
-
- png_set_benign_errors (png_ptr, int allowed);
-
- allowed: 0: treat png_benign_error() as an error.
- 1: treat png_benign_error() as a warning.
-
-As of libpng-1.6.0, the default condition is to treat benign errors as
-warnings while reading and as errors while writing.
-
-.SS Custom chunks
-
-If you need to read or write custom chunks, you may need to get deeper
-into the libpng code. The library now has mechanisms for storing
-and writing chunks of unknown type; you can even declare callbacks
-for custom chunks. However, this may not be good enough if the
-library code itself needs to know about interactions between your
-chunk and existing `intrinsic' chunks.
-
-If you need to write a new intrinsic chunk, first read the PNG
-specification. Acquire a first level of understanding of how it works.
-Pay particular attention to the sections that describe chunk names,
-and look at how other chunks were designed, so you can do things
-similarly. Second, check out the sections of libpng that read and
-write chunks. Try to find a chunk that is similar to yours and use
-it as a template. More details can be found in the comments inside
-the code. It is best to handle private or unknown chunks in a generic method,
-via callback functions, instead of by modifying libpng functions. This
-is illustrated in pngtest.c, which uses a callback function to handle a
-private "vpAg" chunk and the new "sTER" chunk, which are both unknown to
-libpng.
-
-If you wish to write your own transformation for the data, look through
-the part of the code that does the transformations, and check out some of
-the simpler ones to get an idea of how they work. Try to find a similar
-transformation to the one you want to add and copy off of it. More details
-can be found in the comments inside the code itself.
-
-.SS Configuring for gui/windowing platforms:
-
-You will need to write new error and warning functions that use the GUI
-interface, as described previously, and set them to be the error and
-warning functions at the time that png_create_*_struct() is called,
-in order to have them available during the structure initialization.
-They can be changed later via png_set_error_fn(). On some compilers,
-you may also have to change the memory allocators (png_malloc, etc.).
-
-.SS Configuring zlib:
-
-There are special functions to configure the compression. Perhaps the
-most useful one changes the compression level, which currently uses
-input compression values in the range 0 - 9. The library normally
-uses the default compression level (Z_DEFAULT_COMPRESSION = 6). Tests
-have shown that for a large majority of images, compression values in
-the range 3-6 compress nearly as well as higher levels, and do so much
-faster. For online applications it may be desirable to have maximum speed
-(Z_BEST_SPEED = 1). With versions of zlib after v0.99, you can also
-specify no compression (Z_NO_COMPRESSION = 0), but this would create
-files larger than just storing the raw bitmap. You can specify the
-compression level by calling:
-
- #include zlib.h
- png_set_compression_level(png_ptr, level);
-
-Another useful one is to reduce the memory level used by the library.
-The memory level defaults to 8, but it can be lowered if you are
-short on memory (running DOS, for example, where you only have 640K).
-Note that the memory level does have an effect on compression; among
-other things, lower levels will result in sections of incompressible
-data being emitted in smaller stored blocks, with a correspondingly
-larger relative overhead of up to 15% in the worst case.
-
- #include zlib.h
- png_set_compression_mem_level(png_ptr, level);
-
-The other functions are for configuring zlib. They are not recommended
-for normal use and may result in writing an invalid PNG file. See
-zlib.h for more information on what these mean.
-
- #include zlib.h
- png_set_compression_strategy(png_ptr,
- strategy);
-
- png_set_compression_window_bits(png_ptr,
- window_bits);
-
- png_set_compression_method(png_ptr, method);
-
-This controls the size of the IDAT chunks (default 8192):
-
- png_set_compression_buffer_size(png_ptr, size);
-
-As of libpng version 1.5.4, additional APIs became
-available to set these separately for non-IDAT
-compressed chunks such as zTXt, iTXt, and iCCP:
-
- #include zlib.h
- #if PNG_LIBPNG_VER >= 10504
- png_set_text_compression_level(png_ptr, level);
-
- png_set_text_compression_mem_level(png_ptr, level);
-
- png_set_text_compression_strategy(png_ptr,
- strategy);
-
- png_set_text_compression_window_bits(png_ptr,
- window_bits);
-
- png_set_text_compression_method(png_ptr, method);
- #endif
-
-.SS Controlling row filtering
-
-If you want to control whether libpng uses filtering or not, which
-filters are used, and how it goes about picking row filters, you
-can call one of these functions. The selection and configuration
-of row filters can have a significant impact on the size and
-encoding speed and a somewhat lesser impact on the decoding speed
-of an image. Filtering is enabled by default for RGB and grayscale
-images (with and without alpha), but not for paletted images nor
-for any images with bit depths less than 8 bits/pixel.
-
-The 'method' parameter sets the main filtering method, which is
-currently only '0' in the PNG 1.2 specification. The 'filters'
-parameter sets which filter(s), if any, should be used for each
-scanline. Possible values are PNG_ALL_FILTERS, PNG_NO_FILTERS,
-or PNG_FAST_FILTERS to turn filtering on and off, or to turn on
-just the fast-decoding subset of filters, respectively.
-
-Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB,
-PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise
-ORed together with '|' to specify one or more filters to use.
-These filters are described in more detail in the PNG specification.
-If you intend to change the filter type during the course of writing
-the image, you should start with flags set for all of the filters
-you intend to use so that libpng can initialize its internal
-structures appropriately for all of the filter types. (Note that this
-means the first row must always be adaptively filtered, because libpng
-currently does not allocate the filter buffers until png_write_row()
-is called for the first time.)
-
- filters = PNG_NO_FILTERS;
- filters = PNG_ALL_FILTERS;
- filters = PNG_FAST_FILTERS;
-
- or
-
- filters = PNG_FILTER_NONE | PNG_FILTER_SUB |
- PNG_FILTER_UP | PNG_FILTER_AVG |
- PNG_FILTER_PAETH;
-
- png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE,
- filters);
-
- The second parameter can also be
- PNG_INTRAPIXEL_DIFFERENCING if you are
- writing a PNG to be embedded in a MNG
- datastream. This parameter must be the
- same as the value of filter_method used
- in png_set_IHDR().
-
-.SS Requesting debug printout
-
-The macro definition PNG_DEBUG can be used to request debugging
-printout. Set it to an integer value in the range 0 to 3. Higher
-numbers result in increasing amounts of debugging information. The
-information is printed to the "stderr" file, unless another file
-name is specified in the PNG_DEBUG_FILE macro definition.
-
-When PNG_DEBUG > 0, the following functions (macros) become available:
-
- png_debug(level, message)
- png_debug1(level, message, p1)
- png_debug2(level, message, p1, p2)
-
-in which "level" is compared to PNG_DEBUG to decide whether to print
-the message, "message" is the formatted string to be printed,
-and p1 and p2 are parameters that are to be embedded in the string
-according to printf-style formatting directives. For example,
-
- png_debug1(2, "foo=%d", foo);
-
-is expanded to
-
- if (PNG_DEBUG > 2)
- fprintf(PNG_DEBUG_FILE, "foo=%d\en", foo);
-
-When PNG_DEBUG is defined but is zero, the macros aren't defined, but you
-can still use PNG_DEBUG to control your own debugging:
-
- #ifdef PNG_DEBUG
- fprintf(stderr, ...
- #endif
-
-When PNG_DEBUG = 1, the macros are defined, but only png_debug statements
-having level = 0 will be printed. There aren't any such statements in
-this version of libpng, but if you insert some they will be printed.
-
-.SH VII. MNG support
-
-The MNG specification (available at http://www.libpng.org/pub/mng) allows
-certain extensions to PNG for PNG images that are embedded in MNG datastreams.
-Libpng can support some of these extensions. To enable them, use the
-png_permit_mng_features() function:
-
- feature_set = png_permit_mng_features(png_ptr, mask)
-
- mask is a png_uint_32 containing the bitwise OR of the
- features you want to enable. These include
- PNG_FLAG_MNG_EMPTY_PLTE
- PNG_FLAG_MNG_FILTER_64
- PNG_ALL_MNG_FEATURES
-
- feature_set is a png_uint_32 that is the bitwise AND of
- your mask with the set of MNG features that is
- supported by the version of libpng that you are using.
-
-It is an error to use this function when reading or writing a standalone
-PNG file with the PNG 8-byte signature. The PNG datastream must be wrapped
-in a MNG datastream. As a minimum, it must have the MNG 8-byte signature
-and the MHDR and MEND chunks. Libpng does not provide support for these
-or any other MNG chunks; your application must provide its own support for
-them. You may wish to consider using libmng (available at
-https://www.libmng.com/) instead.
-
-.SH VIII. Changes to Libpng from version 0.88
-
-It should be noted that versions of libpng later than 0.96 are not
-distributed by the original libpng author, Guy Schalnat, nor by
-Andreas Dilger, who had taken over from Guy during 1996 and 1997, and
-distributed versions 0.89 through 0.96, but rather by another member
-of the original PNG Group, Glenn Randers-Pehrson. Guy and Andreas are
-still alive and well, but they have moved on to other things.
-
-The old libpng functions png_read_init(), png_write_init(),
-png_info_init(), png_read_destroy(), and png_write_destroy() have been
-moved to PNG_INTERNAL in version 0.95 to discourage their use. These
-functions will be removed from libpng version 1.4.0.
-
-The preferred method of creating and initializing the libpng structures is
-via the png_create_read_struct(), png_create_write_struct(), and
-png_create_info_struct() because they isolate the size of the structures
-from the application, allow version error checking, and also allow the
-use of custom error handling routines during the initialization, which
-the old functions do not. The functions png_read_destroy() and
-png_write_destroy() do not actually free the memory that libpng
-allocated for these structs, but just reset the data structures, so they
-can be used instead of png_destroy_read_struct() and
-png_destroy_write_struct() if you feel there is too much system overhead
-allocating and freeing the png_struct for each image read.
-
-Setting the error callbacks via png_set_message_fn() before
-png_read_init() as was suggested in libpng-0.88 is no longer supported
-because this caused applications that do not use custom error functions
-to fail if the png_ptr was not initialized to zero. It is still possible
-to set the error callbacks AFTER png_read_init(), or to change them with
-png_set_error_fn(), which is essentially the same function, but with a new
-name to force compilation errors with applications that try to use the old
-method.
-
-Support for the sCAL, iCCP, iTXt, and sPLT chunks was added at libpng-1.0.6;
-however, iTXt support was not enabled by default.
-
-Starting with version 1.0.7, you can find out which version of the library
-you are using at run-time:
-
- png_uint_32 libpng_vn = png_access_version_number();
-
-The number libpng_vn is constructed from the major version, minor
-version with leading zero, and release number with leading zero,
-(e.g., libpng_vn for version 1.0.7 is 10007).
-
-Note that this function does not take a png_ptr, so you can call it
-before you've created one.
-
-You can also check which version of png.h you used when compiling your
-application:
-
- png_uint_32 application_vn = PNG_LIBPNG_VER;
-
-.SH IX. Changes to Libpng from version 1.0.x to 1.2.x
-
-Support for user memory management was enabled by default. To
-accomplish this, the functions png_create_read_struct_2(),
-png_create_write_struct_2(), png_set_mem_fn(), png_get_mem_ptr(),
-png_malloc_default(), and png_free_default() were added.
-
-Support for the iTXt chunk has been enabled by default as of
-version 1.2.41.
-
-Support for certain MNG features was enabled.
-
-Support for numbered error messages was added. However, we never got
-around to actually numbering the error messages. The function
-png_set_strip_error_numbers() was added (Note: the prototype for this
-function was inadvertently removed from png.h in PNG_NO_ASSEMBLER_CODE
-builds of libpng-1.2.15. It was restored in libpng-1.2.36).
-
-The png_malloc_warn() function was added at libpng-1.2.3. This issues
-a png_warning and returns NULL instead of aborting when it fails to
-acquire the requested memory allocation.
-
-Support for setting user limits on image width and height was enabled
-by default. The functions png_set_user_limits(), png_get_user_width_max(),
-and png_get_user_height_max() were added at libpng-1.2.6.
-
-The png_set_add_alpha() function was added at libpng-1.2.7.
-
-The function png_set_expand_gray_1_2_4_to_8() was added at libpng-1.2.9.
-Unlike png_set_gray_1_2_4_to_8(), the new function does not expand the
-tRNS chunk to alpha. The png_set_gray_1_2_4_to_8() function is
-deprecated.
-
-A number of macro definitions in support of runtime selection of
-assembler code features (especially Intel MMX code support) were
-added at libpng-1.2.0:
-
- PNG_ASM_FLAG_MMX_SUPPORT_COMPILED
- PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU
- PNG_ASM_FLAG_MMX_READ_COMBINE_ROW
- PNG_ASM_FLAG_MMX_READ_INTERLACE
- PNG_ASM_FLAG_MMX_READ_FILTER_SUB
- PNG_ASM_FLAG_MMX_READ_FILTER_UP
- PNG_ASM_FLAG_MMX_READ_FILTER_AVG
- PNG_ASM_FLAG_MMX_READ_FILTER_PAETH
- PNG_ASM_FLAGS_INITIALIZED
- PNG_MMX_READ_FLAGS
- PNG_MMX_FLAGS
- PNG_MMX_WRITE_FLAGS
- PNG_MMX_FLAGS
-
-We added the following functions in support of runtime
-selection of assembler code features:
-
- png_get_mmx_flagmask()
- png_set_mmx_thresholds()
- png_get_asm_flags()
- png_get_mmx_bitdepth_threshold()
- png_get_mmx_rowbytes_threshold()
- png_set_asm_flags()
-
-We replaced all of these functions with simple stubs in libpng-1.2.20,
-when the Intel assembler code was removed due to a licensing issue.
-
-These macros are deprecated:
-
- PNG_READ_TRANSFORMS_NOT_SUPPORTED
- PNG_PROGRESSIVE_READ_NOT_SUPPORTED
- PNG_NO_SEQUENTIAL_READ_SUPPORTED
- PNG_WRITE_TRANSFORMS_NOT_SUPPORTED
- PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED
- PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED
-
-They have been replaced, respectively, by:
-
- PNG_NO_READ_TRANSFORMS
- PNG_NO_PROGRESSIVE_READ
- PNG_NO_SEQUENTIAL_READ
- PNG_NO_WRITE_TRANSFORMS
- PNG_NO_READ_ANCILLARY_CHUNKS
- PNG_NO_WRITE_ANCILLARY_CHUNKS
-
-PNG_MAX_UINT was replaced with PNG_UINT_31_MAX. It has been
-deprecated since libpng-1.0.16 and libpng-1.2.6.
-
-The function
- png_check_sig(sig, num)
-was replaced with
- !png_sig_cmp(sig, 0, num)
-It has been deprecated since libpng-0.90.
-
-The function
- png_set_gray_1_2_4_to_8()
-which also expands tRNS to alpha was replaced with
- png_set_expand_gray_1_2_4_to_8()
-which does not. It has been deprecated since libpng-1.0.18 and 1.2.9.
-
-.SH X. Changes to Libpng from version 1.0.x/1.2.x to 1.4.x
-
-Private libpng prototypes and macro definitions were moved from
-png.h and pngconf.h into a new pngpriv.h header file.
-
-Functions png_set_benign_errors(), png_benign_error(), and
-png_chunk_benign_error() were added.
-
-Support for setting the maximum amount of memory that the application
-will allocate for reading chunks was added, as a security measure.
-The functions png_set_chunk_cache_max() and png_get_chunk_cache_max()
-were added to the library.
-
-We implemented support for I/O states by adding png_ptr member io_state
-and functions png_get_io_chunk_name() and png_get_io_state() in pngget.c
-
-We added PNG_TRANSFORM_GRAY_TO_RGB to the available high-level
-input transforms.
-
-Checking for and reporting of errors in the IHDR chunk is more thorough.
-
-Support for global arrays was removed, to improve thread safety.
-
-Some obsolete/deprecated macros and functions have been removed.
-
-Typecasted NULL definitions such as
- #define png_voidp_NULL (png_voidp)NULL
-were eliminated. If you used these in your application, just use
-NULL instead.
-
-The png_struct and info_struct members "trans" and "trans_values" were
-changed to "trans_alpha" and "trans_color", respectively.
-
-The obsolete, unused pnggccrd.c and pngvcrd.c files and related makefiles
-were removed.
-
-The PNG_1_0_X and PNG_1_2_X macros were eliminated.
-
-The PNG_LEGACY_SUPPORTED macro was eliminated.
-
-Many WIN32_WCE #ifdefs were removed.
-
-The functions png_read_init(info_ptr), png_write_init(info_ptr),
-png_info_init(info_ptr), png_read_destroy(), and png_write_destroy()
-have been removed. They have been deprecated since libpng-0.95.
-
-The png_permit_empty_plte() was removed. It has been deprecated
-since libpng-1.0.9. Use png_permit_mng_features() instead.
-
-We removed the obsolete stub functions png_get_mmx_flagmask(),
-png_set_mmx_thresholds(), png_get_asm_flags(),
-png_get_mmx_bitdepth_threshold(), png_get_mmx_rowbytes_threshold(),
-png_set_asm_flags(), and png_mmx_supported()
-
-We removed the obsolete png_check_sig(), png_memcpy_check(), and
-png_memset_check() functions. Instead use !png_sig_cmp(), memcpy(),
-and memset(), respectively.
-
-The function png_set_gray_1_2_4_to_8() was removed. It has been
-deprecated since libpng-1.0.18 and 1.2.9, when it was replaced with
-png_set_expand_gray_1_2_4_to_8() because the former function also
-expanded any tRNS chunk to an alpha channel.
-
-Macros for png_get_uint_16, png_get_uint_32, and png_get_int_32
-were added and are used by default instead of the corresponding
-functions. Unfortunately,
-from libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
-function) incorrectly returned a value of type png_uint_32.
-
-We changed the prototype for png_malloc() from
- png_malloc(png_structp png_ptr, png_uint_32 size)
-to
- png_malloc(png_structp png_ptr, png_alloc_size_t size)
-
-This also applies to the prototype for the user replacement malloc_fn().
-
-The png_calloc() function was added and is used in place of
-of "png_malloc(); memset();" except in the case in png_read_png()
-where the array consists of pointers; in this case a "for" loop is used
-after the png_malloc() to set the pointers to NULL, to give robust.
-behavior in case the application runs out of memory part-way through
-the process.
-
-We changed the prototypes of png_get_compression_buffer_size() and
-png_set_compression_buffer_size() to work with png_size_t instead of
-png_uint_32.
-
-Support for numbered error messages was removed by default, since we
-never got around to actually numbering the error messages. The function
-png_set_strip_error_numbers() was removed from the library by default.
-
-The png_zalloc() and png_zfree() functions are no longer exported.
-The png_zalloc() function no longer zeroes out the memory that it
-allocates. Applications that called png_zalloc(png_ptr, number, size)
-can call png_calloc(png_ptr, number*size) instead, and can call
-png_free() instead of png_zfree().
-
-Support for dithering was disabled by default in libpng-1.4.0, because
-it has not been well tested and doesn't actually "dither".
-The code was not
-removed, however, and could be enabled by building libpng with
-PNG_READ_DITHER_SUPPORTED defined. In libpng-1.4.2, this support
-was re-enabled, but the function was renamed png_set_quantize() to
-reflect more accurately what it actually does. At the same time,
-the PNG_DITHER_[RED,GREEN_BLUE]_BITS macros were also renamed to
-PNG_QUANTIZE_[RED,GREEN,BLUE]_BITS, and PNG_READ_DITHER_SUPPORTED
-was renamed to PNG_READ_QUANTIZE_SUPPORTED.
-
-We removed the trailing '.' from the warning and error messages.
-
-.SH XI. Changes to Libpng from version 1.4.x to 1.5.x
-
-From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
-function) incorrectly returned a value of type png_uint_32.
-The incorrect macro was removed from libpng-1.4.5.
-
-Checking for invalid palette index on write was added at libpng
-1.5.10. If a pixel contains an invalid (out-of-range) index libpng issues
-a benign error. This is enabled by default because this condition is an
-error according to the PNG specification, Clause 11.3.2, but the error can
-be ignored in each png_ptr with
-
- png_set_check_for_invalid_index(png_ptr, allowed);
-
- allowed - one of
- 0: disable benign error (accept the
- invalid data without warning).
- 1: enable benign error (treat the
- invalid data as an error or a
- warning).
-
-If the error is ignored, or if png_benign_error() treats it as a warning,
-any invalid pixels are decoded as opaque black by the decoder and written
-as-is by the encoder.
-
-Retrieving the maximum palette index found was added at libpng-1.5.15.
-This statement must appear after png_read_png() or png_read_image() while
-reading, and after png_write_png() or png_write_image() while writing.
-
- int max_palette = png_get_palette_max(png_ptr, info_ptr);
-
-This will return the maximum palette index found in the image, or "\-1" if
-the palette was not checked, or "0" if no palette was found. Note that this
-does not account for any palette index used by ancillary chunks such as the
-bKGD chunk; you must check those separately to determine the maximum
-palette index actually used.
-
-There are no substantial API changes between the non-deprecated parts of
-the 1.4.5 API and the 1.5.0 API; however, the ability to directly access
-members of the main libpng control structures, png_struct and png_info,
-deprecated in earlier versions of libpng, has been completely removed from
-libpng 1.5, and new private "pngstruct.h", "pnginfo.h", and "pngdebug.h"
-header files were created.
-
-We no longer include zlib.h in png.h. The include statement has been moved
-to pngstruct.h, where it is not accessible by applications. Applications that
-need access to information in zlib.h will need to add the '#include "zlib.h"'
-directive. It does not matter whether this is placed prior to or after
-the '"#include png.h"' directive.
-
-The png_sprintf(), png_strcpy(), and png_strncpy() macros are no longer used
-and were removed.
-
-We moved the png_strlen(), png_memcpy(), png_memset(), and png_memcmp()
-macros into a private header file (pngpriv.h) that is not accessible to
-applications.
-
-In png_get_iCCP, the type of "profile" was changed from png_charpp
-to png_bytepp, and in png_set_iCCP, from png_charp to png_const_bytep.
-
-There are changes of form in png.h, including new and changed macros to
-declare parts of the API. Some API functions with arguments that are
-pointers to data not modified within the function have been corrected to
-declare these arguments with PNG_CONST.
-
-Much of the internal use of C macros to control the library build has also
-changed and some of this is visible in the exported header files, in
-particular the use of macros to control data and API elements visible
-during application compilation may require significant revision to
-application code. (It is extremely rare for an application to do this.)
-
-Any program that compiled against libpng 1.4 and did not use deprecated
-features or access internal library structures should compile and work
-against libpng 1.5, except for the change in the prototype for
-png_get_iCCP() and png_set_iCCP() API functions mentioned above.
-
-libpng 1.5.0 adds PNG_ PASS macros to help in the reading and writing of
-interlaced images. The macros return the number of rows and columns in
-each pass and information that can be used to de-interlace and (if
-absolutely necessary) interlace an image.
-
-libpng 1.5.0 adds an API png_longjmp(png_ptr, value). This API calls
-the application-provided png_longjmp_ptr on the internal, but application
-initialized, longjmp buffer. It is provided as a convenience to avoid
-the need to use the png_jmpbuf macro, which had the unnecessary side
-effect of resetting the internal png_longjmp_ptr value.
-
-libpng 1.5.0 includes a complete fixed point API. By default this is
-present along with the corresponding floating point API. In general the
-fixed point API is faster and smaller than the floating point one because
-the PNG file format used fixed point, not floating point. This applies
-even if the library uses floating point in internal calculations. A new
-macro, PNG_FLOATING_ARITHMETIC_SUPPORTED, reveals whether the library
-uses floating point arithmetic (the default) or fixed point arithmetic
-internally for performance critical calculations such as gamma correction.
-In some cases, the gamma calculations may produce slightly different
-results. This has changed the results in png_rgb_to_gray and in alpha
-composition (png_set_background for example). This applies even if the
-original image was already linear (gamma == 1.0) and, therefore, it is
-not necessary to linearize the image. This is because libpng has *not*
-been changed to optimize that case correctly, yet.
-
-Fixed point support for the sCAL chunk comes with an important caveat;
-the sCAL specification uses a decimal encoding of floating point values
-and the accuracy of PNG fixed point values is insufficient for
-representation of these values. Consequently a "string" API
-(png_get_sCAL_s and png_set_sCAL_s) is the only reliable way of reading
-arbitrary sCAL chunks in the absence of either the floating point API or
-internal floating point calculations. Starting with libpng-1.5.0, both
-of these functions are present when PNG_sCAL_SUPPORTED is defined. Prior
-to libpng-1.5.0, their presence also depended upon PNG_FIXED_POINT_SUPPORTED
-being defined and PNG_FLOATING_POINT_SUPPORTED not being defined.
-
-Applications no longer need to include the optional distribution header
-file pngusr.h or define the corresponding macros during application
-build in order to see the correct variant of the libpng API. From 1.5.0
-application code can check for the corresponding _SUPPORTED macro:
-
-#ifdef PNG_INCH_CONVERSIONS_SUPPORTED
- /* code that uses the inch conversion APIs. */
-#endif
-
-This macro will only be defined if the inch conversion functions have been
-compiled into libpng. The full set of macros, and whether or not support
-has been compiled in, are available in the header file pnglibconf.h.
-This header file is specific to the libpng build. Notice that prior to
-1.5.0 the _SUPPORTED macros would always have the default definition unless
-reset by pngusr.h or by explicit settings on the compiler command line.
-These settings may produce compiler warnings or errors in 1.5.0 because
-of macro redefinition.
-
-Applications can now choose whether to use these macros or to call the
-corresponding function by defining PNG_USE_READ_MACROS or
-PNG_NO_USE_READ_MACROS before including png.h. Notice that this is
-only supported from 1.5.0; defining PNG_NO_USE_READ_MACROS prior to 1.5.0
-will lead to a link failure.
-
-Prior to libpng-1.5.4, the zlib compressor used the same set of parameters
-when compressing the IDAT data and textual data such as zTXt and iCCP.
-In libpng-1.5.4 we reinitialized the zlib stream for each type of data.
-We added five png_set_text_*() functions for setting the parameters to
-use with textual data.
-
-Prior to libpng-1.5.4, the PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
-option was off by default, and slightly inaccurate scaling occurred.
-This option can no longer be turned off, and the choice of accurate
-or inaccurate 16-to-8 scaling is by using the new png_set_scale_16_to_8()
-API for accurate scaling or the old png_set_strip_16_to_8() API for simple
-chopping. In libpng-1.5.4, the PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
-macro became PNG_READ_SCALE_16_TO_8_SUPPORTED, and the PNG_READ_16_TO_8
-macro became PNG_READ_STRIP_16_TO_8_SUPPORTED, to enable the two
-png_set_*_16_to_8() functions separately.
-
-Prior to libpng-1.5.4, the png_set_user_limits() function could only be
-used to reduce the width and height limits from the value of
-PNG_USER_WIDTH_MAX and PNG_USER_HEIGHT_MAX, although this document said
-that it could be used to override them. Now this function will reduce or
-increase the limits.
-
-Starting in libpng-1.5.22, default user limits were established. These
-can be overridden by application calls to png_set_user_limits(),
-png_set_user_chunk_cache_max(), and/or png_set_user_malloc_max().
-The limits are now
- max possible default
- png_user_width_max 0x7fffffff 1,000,000
- png_user_height_max 0x7fffffff 1,000,000
- png_user_chunk_cache_max 0 (unlimited) 1000
- png_user_chunk_malloc_max 0 (unlimited) 8,000,000
-
-The png_set_option() function (and the "options" member of the png struct) was
-added to libpng-1.5.15, with option PNG_ARM_NEON.
-
-The library now supports a complete fixed point implementation and can
-thus be used on systems that have no floating point support or very
-limited or slow support. Previously gamma correction, an essential part
-of complete PNG support, required reasonably fast floating point.
-
-As part of this the choice of internal implementation has been made
-independent of the choice of fixed versus floating point APIs and all the
-missing fixed point APIs have been implemented.
-
-The exact mechanism used to control attributes of API functions has
-changed, as described in the INSTALL file.
-
-A new test program, pngvalid, is provided in addition to pngtest.
-pngvalid validates the arithmetic accuracy of the gamma correction
-calculations and includes a number of validations of the file format.
-A subset of the full range of tests is run when "make check" is done
-(in the 'configure' build.) pngvalid also allows total allocated memory
-usage to be evaluated and performs additional memory overwrite validation.
-
-Many changes to individual feature macros have been made. The following
-are the changes most likely to be noticed by library builders who
-configure libpng:
-
-1) All feature macros now have consistent naming:
-
-#define PNG_NO_feature turns the feature off
-#define PNG_feature_SUPPORTED turns the feature on
-
-pnglibconf.h contains one line for each feature macro which is either:
-
-#define PNG_feature_SUPPORTED
-
-if the feature is supported or:
-
-/*#undef PNG_feature_SUPPORTED*/
-
-if it is not. Library code consistently checks for the 'SUPPORTED' macro.
-It does not, and libpng applications should not, check for the 'NO' macro
-which will not normally be defined even if the feature is not supported.
-The 'NO' macros are only used internally for setting or not setting the
-corresponding 'SUPPORTED' macros.
-
-Compatibility with the old names is provided as follows:
-
-PNG_INCH_CONVERSIONS turns on PNG_INCH_CONVERSIONS_SUPPORTED
-
-And the following definitions disable the corresponding feature:
-
-PNG_SETJMP_NOT_SUPPORTED disables SETJMP
-PNG_READ_TRANSFORMS_NOT_SUPPORTED disables READ_TRANSFORMS
-PNG_NO_READ_COMPOSITED_NODIV disables READ_COMPOSITE_NODIV
-PNG_WRITE_TRANSFORMS_NOT_SUPPORTED disables WRITE_TRANSFORMS
-PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED disables READ_ANCILLARY_CHUNKS
-PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED disables WRITE_ANCILLARY_CHUNKS
-
-Library builders should remove use of the above, inconsistent, names.
-
-2) Warning and error message formatting was previously conditional on
-the STDIO feature. The library has been changed to use the
-CONSOLE_IO feature instead. This means that if CONSOLE_IO is disabled
-the library no longer uses the printf(3) functions, even though the
-default read/write implementations use (FILE) style stdio.h functions.
-
-3) Three feature macros now control the fixed/floating point decisions:
-
-PNG_FLOATING_POINT_SUPPORTED enables the floating point APIs
-
-PNG_FIXED_POINT_SUPPORTED enables the fixed point APIs; however, in
-practice these are normally required internally anyway (because the PNG
-file format is fixed point), therefore in most cases PNG_NO_FIXED_POINT
-merely stops the function from being exported.
-
-PNG_FLOATING_ARITHMETIC_SUPPORTED chooses between the internal floating
-point implementation or the fixed point one. Typically the fixed point
-implementation is larger and slower than the floating point implementation
-on a system that supports floating point; however, it may be faster on a
-system which lacks floating point hardware and therefore uses a software
-emulation.
-
-4) Added PNG_{READ,WRITE}_INT_FUNCTIONS_SUPPORTED. This allows the
-functions to read and write ints to be disabled independently of
-PNG_USE_READ_MACROS, which allows libpng to be built with the functions
-even though the default is to use the macros - this allows applications
-to choose at app buildtime whether or not to use macros (previously
-impossible because the functions weren't in the default build.)
-
-.SH XII. Changes to Libpng from version 1.5.x to 1.6.x
-
-A "simplified API" has been added (see documentation in png.h and a simple
-example in contrib/examples/pngtopng.c). The new publicly visible API
-includes the following:
-
- macros:
- PNG_FORMAT_*
- PNG_IMAGE_*
- structures:
- png_control
- png_image
- read functions
- png_image_begin_read_from_file()
- png_image_begin_read_from_stdio()
- png_image_begin_read_from_memory()
- png_image_finish_read()
- png_image_free()
- write functions
- png_image_write_to_file()
- png_image_write_to_memory()
- png_image_write_to_stdio()
-
-Starting with libpng-1.6.0, you can configure libpng to prefix all exported
-symbols, using the PNG_PREFIX macro.
-
-We no longer include string.h in png.h. The include statement has been moved
-to pngpriv.h, where it is not accessible by applications. Applications that
-need access to information in string.h must add an '#include <string.h>'
-directive. It does not matter whether this is placed prior to or after
-the '#include "png.h"' directive.
-
-The following API are now DEPRECATED:
- png_info_init_3()
- png_convert_to_rfc1123() which has been replaced
- with png_convert_to_rfc1123_buffer()
- png_malloc_default()
- png_free_default()
- png_reset_zstream()
-
-The following have been removed:
- png_get_io_chunk_name(), which has been replaced
- with png_get_io_chunk_type(). The new
- function returns a 32-bit integer instead of
- a string.
- The png_sizeof(), png_strlen(), png_memcpy(), png_memcmp(), and
- png_memset() macros are no longer used in the libpng sources and
- have been removed. These had already been made invisible to applications
- (i.e., defined in the private pngpriv.h header file) since libpng-1.5.0.
-
-The signatures of many exported functions were changed, such that
- png_structp became png_structrp or png_const_structrp
- png_infop became png_inforp or png_const_inforp
-where "rp" indicates a "restricted pointer".
-
-Dropped support for 16-bit platforms. The support for FAR/far types has
-been eliminated and the definition of png_alloc_size_t is now controlled
-by a flag so that 'small size_t' systems can select it if necessary.
-
-Error detection in some chunks has improved; in particular the iCCP chunk
-reader now does pretty complete validation of the basic format. Some bad
-profiles that were previously accepted are now accepted with a warning or
-rejected, depending upon the png_set_benign_errors() setting, in particular
-the very old broken Microsoft/HP 3144-byte sRGB profile. Starting with
-libpng-1.6.11, recognizing and checking sRGB profiles can be avoided by
-means of
-
- #if defined(PNG_SKIP_sRGB_CHECK_PROFILE) && \
- defined(PNG_SET_OPTION_SUPPORTED)
- png_set_option(png_ptr, PNG_SKIP_sRGB_CHECK_PROFILE,
- PNG_OPTION_ON);
- #endif
-
-It's not a good idea to do this if you are using the "simplified API",
-which needs to be able to recognize sRGB profiles conveyed via the iCCP
-chunk.
-
-The PNG spec requirement that only grayscale profiles may appear in images
-with color type 0 or 4 and that even if the image only contains gray pixels,
-only RGB profiles may appear in images with color type 2, 3, or 6, is now
-enforced. The sRGB chunk is allowed to appear in images with any color type
-and is interpreted by libpng to convey a one-tracer-curve gray profile or a
-three-tracer-curve RGB profile as appropriate.
-
-Libpng 1.5.x erroneously used /MD for Debug DLL builds; if you used the debug
-builds in your app and you changed your app to use /MD you will need to
-change it back to /MDd for libpng 1.6.x.
-
-Prior to libpng-1.6.0 a warning would be issued if the iTXt chunk contained
-an empty language field or an empty translated keyword. Both of these
-are allowed by the PNG specification, so these warnings are no longer issued.
-
-The library now issues an error if the application attempts to set a
-transform after it calls png_read_update_info() or if it attempts to call
-both png_read_update_info() and png_start_read_image() or to call either
-of them more than once.
-
-The default condition for benign_errors is now to treat benign errors as
-warnings while reading and as errors while writing.
-
-The library now issues a warning if both background processing and RGB to
-gray are used when gamma correction happens. As with previous versions of
-the library the results are numerically very incorrect in this case.
-
-There are some minor arithmetic changes in some transforms such as
-png_set_background(), that might be detected by certain regression tests.
-
-Unknown chunk handling has been improved internally, without any API change.
-This adds more correct option control of the unknown handling, corrects
-a pre-existing bug where the per-chunk 'keep' setting is ignored, and makes
-it possible to skip IDAT chunks in the sequential reader.
-
-The machine-generated configure files are no longer included in branches
-libpng16 and later of the GIT repository. They continue to be included
-in the tarball releases, however.
-
-Libpng-1.6.0 through 1.6.2 used the CMF bytes at the beginning of the IDAT
-stream to set the size of the sliding window for reading instead of using the
-default 32-kbyte sliding window size. It was discovered that there are
-hundreds of PNG files in the wild that have incorrect CMF bytes that caused
-zlib to issue the "invalid distance too far back" error and reject the file.
-Libpng-1.6.3 and later calculate their own safe CMF from the image dimensions,
-provide a way to revert to the libpng-1.5.x behavior (ignoring the CMF bytes
-and using a 32-kbyte sliding window), by using
-
- png_set_option(png_ptr, PNG_MAXIMUM_INFLATE_WINDOW,
- PNG_OPTION_ON);
-
-and provide a tool (contrib/tools/pngfix) for rewriting a PNG file while
-optimizing the CMF bytes in its IDAT chunk correctly.
-
-Libpng-1.6.0 and libpng-1.6.1 wrote uncompressed iTXt chunks with the wrong
-length, which resulted in PNG files that cannot be read beyond the bad iTXt
-chunk. This error was fixed in libpng-1.6.3, and a tool (called
-contrib/tools/png-fix-itxt) has been added to the libpng distribution.
-
-Starting with libpng-1.6.17, the PNG_SAFE_LIMITS macro was eliminated
-and safe limits are used by default (users who need larger limits
-can still override them at compile time or run time, as described above).
-
-The new limits are
- default spec limit
- png_user_width_max 1,000,000 2,147,483,647
- png_user_height_max 1,000,000 2,147,483,647
- png_user_chunk_cache_max 128 unlimited
- png_user_chunk_malloc_max 8,000,000 unlimited
-
-Starting with libpng-1.6.18, a PNG_RELEASE_BUILD macro was added, which allows
-library builders to control compilation for an installed system (a release build).
-It can be set for testing debug or beta builds to ensure that they will compile
-when the build type is switched to RC or STABLE. In essence this overrides the
-PNG_LIBPNG_BUILD_BASE_TYPE definition which is not directly user controllable.
-
-Starting with libpng-1.6.19, attempting to set an over-length PLTE chunk
-is an error. Previously this requirement of the PNG specification was not
-enforced, and the palette was always limited to 256 entries. An over-length
-PLTE chunk found in an input PNG is silently truncated.
-
-Starting with libpng-1.6.31, the eXIf chunk is supported. Libpng does not
-attempt to decode the Exif profile; it simply returns a byte array
-containing the profile to the calling application which must do its own
-decoding.
-
-.SH XIII. Detecting libpng
-
-The png_get_io_ptr() function has been present since libpng-0.88, has never
-changed, and is unaffected by conditional compilation macros. It is the
-best choice for use in configure scripts for detecting the presence of any
-libpng version since 0.88. In an autoconf "configure.in" you could use
-
- AC_CHECK_LIB(png, png_get_io_ptr, ...
-
-.SH XV. Source code repository
-
-Since about February 2009, version 1.2.34, libpng has been under "git" source
-control. The git repository was built from old libpng-x.y.z.tar.gz files
-going back to version 0.70. You can access the git repository (read only)
-at
-
- https://github.com/glennrp/libpng or
- https://git.code.sf.net/p/libpng/code.git
-
-or you can browse it with a web browser at
-
- https://github.com/glennrp/libpng or
- https://sourceforge.net/p/libpng/code/ci/libpng16/tree/
-
-Patches can be sent to glennrp at users.sourceforge.net or to
-png-mng-implement at lists.sourceforge.net or you can upload them to
-the libpng bug tracker at
-
- https://libpng.sourceforge.io/
-
-or as a "pull request" to
-
- https://github.com/glennrp/libpng/pulls
-
-We also accept patches built from the tar or zip distributions, and
-simple verbal discriptions of bug fixes, reported either to the
-SourceForge bug tracker, to the png-mng-implement at lists.sf.net
-mailing list, as github issues, or directly to glennrp.
-
-.SH XV. Coding style
-
-Our coding style is similar to the "Allman" style
-(See https://en.wikipedia.org/wiki/Indent_style#Allman_style), with curly
-braces on separate lines:
-
- if (condition)
- {
- action;
- }
-
- else if (another condition)
- {
- another action;
- }
-
-The braces can be omitted from simple one-line actions:
-
- if (condition)
- return (0);
-
-We use 3-space indentation, except for continued statements which
-are usually indented the same as the first line of the statement
-plus four more spaces.
-
-For macro definitions we use 2-space indentation, always leaving the "#"
-in the first column.
-
- #ifndef PNG_NO_FEATURE
- # ifndef PNG_FEATURE_SUPPORTED
- # define PNG_FEATURE_SUPPORTED
- # endif
- #endif
-
-Comments appear with the leading "/*" at the same indentation as
-the statement that follows the comment:
-
- /* Single-line comment */
- statement;
-
- /* This is a multiple-line
- * comment.
- */
- statement;
-
-Very short comments can be placed after the end of the statement
-to which they pertain:
-
- statement; /* comment */
-
-We don't use C++ style ("//") comments. We have, however,
-used them in the past in some now-abandoned MMX assembler
-code.
-
-Functions and their curly braces are not indented, and
-exported functions are marked with PNGAPI:
-
- /* This is a public function that is visible to
- * application programmers. It does thus-and-so.
- */
- void PNGAPI
- png_exported_function(png_ptr, png_info, foo)
- {
- body;
- }
-
-The return type and decorations are placed on a separate line
-ahead of the function name, as illustrated above.
-
-The prototypes for all exported functions appear in png.h,
-above the comment that says
-
- /* Maintainer: Put new public prototypes here ... */
-
-We mark all non-exported functions with "/* PRIVATE */"":
-
- void /* PRIVATE */
- png_non_exported_function(png_ptr, png_info, foo)
- {
- body;
- }
-
-The prototypes for non-exported functions (except for those in
-pngtest) appear in pngpriv.h above the comment that says
-
- /* Maintainer: Put new private prototypes here ^ */
-
-To avoid polluting the global namespace, the names of all exported
-functions and variables begin with "png_", and all publicly visible C
-preprocessor macros begin with "PNG". We request that applications that
-use libpng *not* begin any of their own symbols with either of these strings.
-
-We put a space after the "sizeof" operator and we omit the
-optional parentheses around its argument when the argument
-is an expression, not a type name, and we always enclose the
-sizeof operator, with its argument, in parentheses:
-
- (sizeof (png_uint_32))
- (sizeof array)
-
-Prior to libpng-1.6.0 we used a "png_sizeof()" macro, formatted as
-though it were a function.
-
-Control keywords if, for, while, and switch are always followed by a space
-to distinguish them from function calls, which have no trailing space.
-
-We put a space after each comma and after each semicolon
-in "for" statements, and we put spaces before and after each
-C binary operator and after "for" or "while", and before
-"?". We don't put a space between a typecast and the expression
-being cast, nor do we put one between a function name and the
-left parenthesis that follows it:
-
- for (i = 2; i > 0; \-\-i)
- y[i] = a(x) + (int)b;
-
-We prefer #ifdef and #ifndef to #if defined() and #if !defined()
-when there is only one macro being tested. We always use parentheses
-with "defined".
-
-We express integer constants that are used as bit masks in hex format,
-with an even number of lower-case hex digits, and to make them unsigned
-(e.g., 0x00U, 0xffU, 0x0100U) and long if they are greater than 0x7fff
-(e.g., 0xffffUL).
-
-We prefer to use underscores rather than camelCase in names, except
-for a few type names that we inherit from zlib.h.
-
-We prefer "if (something != 0)" and "if (something == 0)" over
-"if (something)" and if "(!something)", respectively, and for pointers
-we prefer "if (some_pointer != NULL)" or "if (some_pointer == NULL)".
-
-We do not use the TAB character for indentation in the C sources.
-
-Lines do not exceed 80 characters.
-
-Other rules can be inferred by inspecting the libpng source.
-
-.SH XVI. Y2K Compliance in libpng
-
-Since the PNG Development group is an ad-hoc body, we can't make
-an official declaration.
-
-This is your unofficial assurance that libpng from version 0.71 and
-upward through 1.6.31 are Y2K compliant. It is my belief that earlier
-versions were also Y2K compliant.
-
-Libpng only has two year fields. One is a 2-byte unsigned integer
-that will hold years up to 65535. The other, which is deprecated,
-holds the date in text format, and will hold years up to 9999.
-
-The integer is
- "png_uint_16 year" in png_time_struct.
-
-The string is
- "char time_buffer[29]" in png_struct. This is no longer used
-in libpng-1.6.x and will be removed from libpng-1.7.0.
-
-There are seven time-related functions:
-
- png_convert_to_rfc_1123_buffer() in png.c
- (formerly png_convert_to_rfc_1152() in error, and
- also formerly png_convert_to_rfc_1123())
- png_convert_from_struct_tm() in pngwrite.c, called
- in pngwrite.c
- png_convert_from_time_t() in pngwrite.c
- png_get_tIME() in pngget.c
- png_handle_tIME() in pngrutil.c, called in pngread.c
- png_set_tIME() in pngset.c
- png_write_tIME() in pngwutil.c, called in pngwrite.c
-
-All appear to handle dates properly in a Y2K environment. The
-png_convert_from_time_t() function calls gmtime() to convert from system
-clock time, which returns (year - 1900), which we properly convert to
-the full 4-digit year. There is a possibility that applications using
-libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
-function, or that they are incorrectly passing only a 2-digit year
-instead of "year - 1900" into the png_convert_from_struct_tm() function,
-but this is not under our control. The libpng documentation has always
-stated that it works with 4-digit years, and the APIs have been
-documented as such.
-
-The tIME chunk itself is also Y2K compliant. It uses a 2-byte unsigned
-integer to hold the year, and can hold years as large as 65535.
-
-zlib, upon which libpng depends, is also Y2K compliant. It contains
-no date-related code.
-
-
- Glenn Randers-Pehrson
- libpng maintainer
- PNG Development Group
-
-.SH NOTE
-
-Note about libpng version numbers:
-
-Due to various miscommunications, unforeseen code incompatibilities
-and occasional factors outside the authors' control, version numbering
-on the library has not always been consistent and straightforward.
-The following table summarizes matters since version 0.89c, which was
-the first widely used release:
-
- source png.h png.h shared-lib
- version string int version
- ------- ------ ----- ----------
- 0.89c "1.0 beta 3" 0.89 89 1.0.89
- 0.90 "1.0 beta 4" 0.90 90 0.90 [should have been 2.0.90]
- 0.95 "1.0 beta 5" 0.95 95 0.95 [should have been 2.0.95]
- 0.96 "1.0 beta 6" 0.96 96 0.96 [should have been 2.0.96]
- 0.97b "1.00.97 beta 7" 1.00.97 97 1.0.1 [should have been 2.0.97]
- 0.97c 0.97 97 2.0.97
- 0.98 0.98 98 2.0.98
- 0.99 0.99 98 2.0.99
- 0.99a-m 0.99 99 2.0.99
- 1.00 1.00 100 2.1.0 [100 should be 10000]
- 1.0.0 (from here on, the 100 2.1.0 [100 should be 10000]
- 1.0.1 png.h string is 10001 2.1.0
- 1.0.1a-e identical to the 10002 from here on, the shared library
- 1.0.2 source version) 10002 is 2.V where V is the source code
- 1.0.2a-b 10003 version, except as noted.
- 1.0.3 10003
- 1.0.3a-d 10004
- 1.0.4 10004
- 1.0.4a-f 10005
- 1.0.5 (+ 2 patches) 10005
- 1.0.5a-d 10006
- 1.0.5e-r 10100 (not source compatible)
- 1.0.5s-v 10006 (not binary compatible)
- 1.0.6 (+ 3 patches) 10006 (still binary incompatible)
- 1.0.6d-f 10007 (still binary incompatible)
- 1.0.6g 10007
- 1.0.6h 10007 10.6h (testing xy.z so-numbering)
- 1.0.6i 10007 10.6i
- 1.0.6j 10007 2.1.0.6j (incompatible with 1.0.0)
- 1.0.7beta11-14 DLLNUM 10007 2.1.0.7beta11-14 (binary compatible)
- 1.0.7beta15-18 1 10007 2.1.0.7beta15-18 (binary compatible)
- 1.0.7rc1-2 1 10007 2.1.0.7rc1-2 (binary compatible)
- 1.0.7 1 10007 (still compatible)
- ...
- 1.0.19 10 10019 10.so.0.19[.0]
- ...
- 1.2.57 13 10257 12.so.0.56[.0]
- ...
- 1.5.28 15 10528 15.so.15.28[.0]
- ...
- 1.6.31 16 10631 16.so.16.31[.0]
-
-Henceforth the source version will match the shared-library minor
-and patch numbers; the shared-library major version number will be
-used for changes in backward compatibility, as it is intended. The
-PNG_PNGLIB_VER macro, which is not used within libpng but is available
-for applications, is an unsigned integer of the form xyyzz corresponding
-to the source version x.y.z (leading zeros in y and z). Beta versions
-were given the previous public release number plus a letter, until
-version 1.0.6j; from then on they were given the upcoming public
-release number plus "betaNN" or "rcNN".
-
-.SH "SEE ALSO"
-.IR libpngpf(3) ", " png(5)
-.LP
-.IR libpng :
-.IP
-https://libpng.sourceforge.io/ (follow the [DOWNLOAD] link)
-http://www.libpng.org/pub/png
-
-.LP
-.IR zlib :
-.IP
-(generally) at the same location as
-.I libpng
-or at
-.br
-https://zlib.net/
-
-.LP
-.IR PNG specification: RFC 2083
-.IP
-(generally) at the same location as
-.I libpng
-or at
-.br
-https://www.ietf.org/rfc/rfc2083.txt
-.br
-or (as a W3C Recommendation) at
-.br
-https://www.w3.org/TR/REC-png.html
-
-.LP
-In the case of any inconsistency between the PNG specification
-and this library, the specification takes precedence.
-
-.SH AUTHORS
-This man page: Glenn Randers-Pehrson
-<glennrp at users.sourceforge.net>
-
-The contributing authors would like to thank all those who helped
-with testing, bug fixes, and patience. This wouldn't have been
-possible without all of you.
-
-Thanks to Frank J. T. Wojcik for helping with the documentation.
-
-Libpng version 1.6.31 - July 27, 2017:
-Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
-Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
-
-Supported by the PNG development group
-.br
-png-mng-implement at lists.sf.net
-(subscription required; visit
-png-mng-implement at lists.sourceforge.net (subscription required; visit
-https://lists.sourceforge.net/lists/listinfo/png-mng-implement
-to subscribe).
-
-.SH NOTICES:
-
-This copy of the libpng notices is provided for your convenience. In case of
-any discrepancy between this copy and the notices in the file png.h that is
-included in the libpng distribution, the latter shall prevail.
-
-COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
-
-If you modify libpng you may insert additional notices immediately following
-this sentence.
-
-This code is released under the libpng license.
-
-libpng versions 1.0.7, July 1, 2000 through 1.6.31, July 27, 2017 are
-Copyright (c) 2000-2002, 2004, 2006-2017 Glenn Randers-Pehrson, are
-derived from libpng-1.0.6, and are distributed according to the same
-disclaimer and license as libpng-1.0.6 with the following individuals
-added to the list of Contributing Authors:
-
- Simon-Pierre Cadieux
- Eric S. Raymond
- Mans Rullgard
- Cosmin Truta
- Gilles Vollant
- James Yu
- Mandar Sahastrabuddhe
- Google Inc.
- Vadim Barkov
-
-and with the following additions to the disclaimer:
-
- There is no warranty against interference with your enjoyment of the
- library or against infringement. There is no warranty that our
- efforts or the library will fulfill any of your particular purposes
- or needs. This library is provided with all faults, and the entire
- risk of satisfactory quality, performance, accuracy, and effort is with
- the user.
-
-Some files in the "contrib" directory and some configure-generated
-files that are distributed with libpng have other copyright owners and
-are released under other open source licenses.
-
-libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
-Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
-libpng-0.96, and are distributed according to the same disclaimer and
-license as libpng-0.96, with the following individuals added to the list
-of Contributing Authors:
-
- Tom Lane
- Glenn Randers-Pehrson
- Willem van Schaik
-
-libpng versions 0.89, June 1996, through 0.96, May 1997, are
-Copyright (c) 1996-1997 Andreas Dilger, are derived from libpng-0.88,
-and are distributed according to the same disclaimer and license as
-libpng-0.88, with the following individuals added to the list of
-Contributing Authors:
-
- John Bowler
- Kevin Bracey
- Sam Bushell
- Magnus Holmgren
- Greg Roelofs
- Tom Tanner
-
-Some files in the "scripts" directory have other copyright owners
-but are released under this license.
-
-libpng versions 0.5, May 1995, through 0.88, January 1996, are
-Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
-
-For the purposes of this copyright and license, "Contributing Authors"
-is defined as the following set of individuals:
-
- Andreas Dilger
- Dave Martindale
- Guy Eric Schalnat
- Paul Schmidt
- Tim Wegner
-
-The PNG Reference Library is supplied "AS IS". The Contributing Authors
-and Group 42, Inc. disclaim all warranties, expressed or implied,
-including, without limitation, the warranties of merchantability and of
-fitness for any purpose. The Contributing Authors and Group 42, Inc.
-assume no liability for direct, indirect, incidental, special, exemplary,
-or consequential damages, which may result from the use of the PNG
-Reference Library, even if advised of the possibility of such damage.
-
-Permission is hereby granted to use, copy, modify, and distribute this
-source code, or portions hereof, for any purpose, without fee, subject
-to the following restrictions:
-
- 1. The origin of this source code must not be misrepresented.
-
- 2. Altered versions must be plainly marked as such and must not
- be misrepresented as being the original source.
-
- 3. This Copyright notice may not be removed or altered from any
- source or altered source distribution.
-
-The Contributing Authors and Group 42, Inc. specifically permit, without
-fee, and encourage the use of this source code as a component to
-supporting the PNG file format in commercial products. If you use this
-source code in a product, acknowledgment is not required but would be
-appreciated.
-
-END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.
-
-TRADEMARK:
-
-The name "libpng" has not been registered by the Copyright owner
-as a trademark in any jurisdiction. However, because libpng has
-been distributed and maintained world-wide, continually since 1995,
-the Copyright owner claims "common-law trademark protection" in any
-jurisdiction where common-law trademark is recognized.
-
-OSI CERTIFICATION:
-
-Libpng is OSI Certified Open Source Software. OSI Certified Open Source is
-a certification mark of the Open Source Initiative. OSI has not addressed
-the additional disclaimers inserted at version 1.0.7.
-
-EXPORT CONTROL:
-
-The Copyright owner believes that the Export Control Classification
-Number (ECCN) for libpng is EAR99, which means not subject to export
-controls or International Traffic in Arms Regulations (ITAR) because
-it is open source, publicly available software, that does not contain
-any encryption software. See the EAR, paragraphs 734.3(b)(3) and
-734.7(b).
-
-A "png_get_copyright" function is available, for convenient use in "about"
-boxes and the like:
-
- printf("%s", png_get_copyright(NULL));
-
-Also, the PNG logo (in PNG format, of course) is supplied in the
-files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
-
-Glenn Randers-Pehrson
-glennrp at users.sourceforge.net
-July 27, 2017
-
-.\" end of man page
-
diff --git a/plugins/AdvaImg/src/LibPNG/libpngpf.3 b/plugins/AdvaImg/src/LibPNG/libpngpf.3 deleted file mode 100644 index ade6d634a4..0000000000 --- a/plugins/AdvaImg/src/LibPNG/libpngpf.3 +++ /dev/null @@ -1,18 +0,0 @@ -.TH LIBPNGPF 3 "April 1, 2017"
-.SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.31
-(private functions)
-.SH SYNOPSIS
-\fB\fB#include \fI\fI"pngpriv.h"
-
-\fB\fBAs of libpng version \fP\fI\fP\fI1.5.1\fP\fB\fP\fB, this section is no longer \fP\fI\fP\fImaintained\fP\fB\fP\fB, now that the private function prototypes are hidden in pngpriv.h and not accessible to applications. Look in pngpriv.h for the prototypes and a short description of each \fI\fIfunction.
-
-.SH DESCRIPTION
-The functions previously listed here are used privately by libpng and are not
-available for use by applications. They are not "exported" to applications
-using shared libraries.
-
-.SH SEE ALSO
-.BR "png"(5), " libpng"(3), " zlib"(3), " deflate"(5), " " and " zlib"(5)
-.SH AUTHOR
-Glenn Randers-Pehrson
diff --git a/plugins/AdvaImg/src/LibPNG/png.5 b/plugins/AdvaImg/src/LibPNG/png.5 deleted file mode 100644 index fea3610bc7..0000000000 --- a/plugins/AdvaImg/src/LibPNG/png.5 +++ /dev/null @@ -1,74 +0,0 @@ -.TH PNG 5 "April 1, 2017"
-.SH NAME
-png \- Portable Network Graphics (PNG) format
-.SH DESCRIPTION
-PNG (Portable Network Graphics) is an extensible file format for the
-lossless, portable, well-compressed storage of raster images. PNG provides
-a patent-free replacement for GIF and can also replace many
-common uses of TIFF. Indexed-color, grayscale, and truecolor images are
-supported, plus an optional alpha channel. Sample depths range from
-1 to 16 bits.
-.br
-
-PNG is designed to work well in online viewing applications, such as the
-World Wide Web, so it is fully streamable with a progressive display
-option. PNG is robust, providing both full file integrity checking and
-fast, simple detection of common transmission errors. Also, PNG can store
-gamma and chromaticity data for improved color matching on heterogeneous
-platforms.
-
-.SH "SEE ALSO"
-.BR "libpng"(3), " libpngpf"(3), " zlib"(3), " deflate"(5), " " and " zlib"(5)
-.LP
-PNG specification (second edition), November 2003:
-.IP
-.br
- <https://www.w3.org/TR/2003/REC-PNG-20031110/
-PNG 1.2 specification, July 1999:
-.IP
-.br
-https://png-mng.sourceforge.io/pub/png/spec/1.2/
-.LP
-PNG 1.0 specification, October 1996:
-.IP
-.br
-RFC 2083
-.IP
-.br
-https://www.ietf.org/rfc/rfc2083.txt
-.br
-or (as a W3C Recommendation) at
-.br
-https://www.w3.org/TR/REC-png-961001
-.SH AUTHORS
-This man page: Glenn Randers-Pehrson
-.LP
-Portable Network Graphics (PNG) Specification (Second Edition)
-Information technology - Computer graphics and image processing -
-Portable Network Graphics (PNG): Functional specification.
-ISO/IEC 15948:2003 (E) (November 10, 2003): David Duce and others.
-.LP
-Portable Network Graphics (PNG) Specification Version 1.2 (July 8, 1999):
-Glenn Randers-Pehrson and others (png-list).
-.LP
-Portable Network Graphics (PNG) Specification Version 1.0 (October 1, 1996):
-Thomas Boutell and others (png-list).
-.LP
-
-
-.SH COPYRIGHT NOTICE
-.LP
-This man page is Copyright (c) 1998-2006 Glenn Randers-Pehrson. See png.h
-for conditions of use and distribution.
-.LP
-The PNG Specification (Second Edition) is
-Copyright (c) 2003 W3C. (MIT, ERCIM, Keio), All Rights Reserved.
-.LP
-The PNG-1.2 specification is copyright (c) 1999 Glenn Randers-Pehrson.
-See the specification for conditions of use and distribution.
-.LP
-The PNG-1.0 specification is copyright (c) 1996 Massachusetts Institute of
-Technology. See the specification for conditions of use and distribution.
-.LP
-.\" end of man page
-
diff --git a/plugins/AdvaImg/src/LibPNG/png.c b/plugins/AdvaImg/src/LibPNG/png.c index 91fb654d04..a7dadf6595 100644 --- a/plugins/AdvaImg/src/LibPNG/png.c +++ b/plugins/AdvaImg/src/LibPNG/png.c @@ -1,7 +1,7 @@ /* png.c - location for general purpose libpng functions
*
- * Last changed in libpng 1.6.31 [July 27, 2017]
+ * Last changed in libpng 1.6.33 [September 28, 2017]
* Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -14,7 +14,7 @@ #include "pngpriv.h"
/* Generate a compiler error if there is an old png.h in the search path. */
-typedef png_libpng_version_1_6_31 Your_png_h_is_not_version_1_6_31;
+typedef png_libpng_version_1_6_34 Your_png_h_is_not_version_1_6_34;
#ifdef __GNUC__
/* The version tests may need to be added to, but the problem warning has
@@ -619,8 +619,18 @@ png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask, /* Free any eXIf entry */
if (((mask & PNG_FREE_EXIF) & info_ptr->free_me) != 0)
{
- png_free(png_ptr, info_ptr->exif);
- info_ptr->exif = NULL;
+# ifdef PNG_READ_eXIf_SUPPORTED
+ if (info_ptr->eXIf_buf)
+ {
+ png_free(png_ptr, info_ptr->eXIf_buf);
+ info_ptr->eXIf_buf = NULL;
+ }
+# endif
+ if (info_ptr->exif)
+ {
+ png_free(png_ptr, info_ptr->exif);
+ info_ptr->exif = NULL;
+ }
info_ptr->valid &= ~PNG_INFO_eXIf;
}
#endif
@@ -806,14 +816,14 @@ png_get_copyright(png_const_structrp png_ptr) #else
# ifdef __STDC__
return PNG_STRING_NEWLINE \
- "libpng version 1.6.31 - July 27, 2017" PNG_STRING_NEWLINE \
+ "libpng version 1.6.34 - September 29, 2017" PNG_STRING_NEWLINE \
"Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson" \
PNG_STRING_NEWLINE \
"Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
"Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
PNG_STRING_NEWLINE;
# else
- return "libpng version 1.6.31 - July 27, 2017\
+ return "libpng version 1.6.34 - September 29, 2017\
Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson\
Copyright (c) 1996-1997 Andreas Dilger\
Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
@@ -1903,12 +1913,12 @@ png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace, */
if (intent < 0 || intent >= PNG_sRGB_INTENT_LAST)
return png_icc_profile_error(png_ptr, colorspace, "sRGB",
- (unsigned)intent, "invalid sRGB rendering intent");
+ (png_alloc_size_t)intent, "invalid sRGB rendering intent");
if ((colorspace->flags & PNG_COLORSPACE_HAVE_INTENT) != 0 &&
colorspace->rendering_intent != intent)
return png_icc_profile_error(png_ptr, colorspace, "sRGB",
- (unsigned)intent, "inconsistent rendering intents");
+ (png_alloc_size_t)intent, "inconsistent rendering intents");
if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0)
{
@@ -1969,7 +1979,6 @@ icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace, if (profile_length < 132)
return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
"too short");
-
return 1;
}
@@ -2214,22 +2223,23 @@ png_icc_check_tag_table(png_const_structrp png_ptr, png_colorspacerp colorspace, * being in range. All defined tag types have an 8 byte header - a 4 byte
* type signature then 0.
*/
+
+ /* This is a hard error; potentially it can cause read outside the
+ * profile.
+ */
+ if (tag_start > profile_length || tag_length > profile_length - tag_start)
+ return png_icc_profile_error(png_ptr, colorspace, name, tag_id,
+ "ICC profile tag outside profile");
+
if ((tag_start & 3) != 0)
{
- /* CNHP730S.icc shipped with Microsoft Windows 64 violates this, it is
+ /* CNHP730S.icc shipped with Microsoft Windows 64 violates this; it is
* only a warning here because libpng does not care about the
* alignment.
*/
(void)png_icc_profile_error(png_ptr, NULL, name, tag_id,
"ICC profile tag start not a multiple of 4");
}
-
- /* This is a hard error; potentially it can cause read outside the
- * profile.
- */
- if (tag_start > profile_length || tag_length > profile_length - tag_start)
- return png_icc_profile_error(png_ptr, colorspace, name, tag_id,
- "ICC profile tag outside profile");
}
return 1; /* success, maybe with warnings */
@@ -3751,7 +3761,7 @@ png_log16bit(png_uint_32 x) * of getting this accuracy in practice.
*
* To deal with this the following exp() function works out the exponent of the
- * frational part of the logarithm by using an accurate 32-bit value from the
+ * fractional part of the logarithm by using an accurate 32-bit value from the
* top four fractional bits then multiplying in the remaining bits.
*/
static const png_uint_32
diff --git a/plugins/AdvaImg/src/LibPNG/png.h b/plugins/AdvaImg/src/LibPNG/png.h index 4572030c18..62d27ada00 100644 --- a/plugins/AdvaImg/src/LibPNG/png.h +++ b/plugins/AdvaImg/src/LibPNG/png.h @@ -1,7 +1,7 @@ /* png.h - header file for PNG reference library
*
- * libpng version 1.6.31, July 27, 2017
+ * libpng version 1.6.34, September 29, 2017
*
* Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -12,7 +12,7 @@ * Authors and maintainers:
* libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
* libpng versions 0.89, June 1996, through 0.96, May 1997: Andreas Dilger
- * libpng versions 0.97, January 1998, through 1.6.31, July 27, 2017:
+ * libpng versions 0.97, January 1998, through 1.6.34, September 29, 2017:
* Glenn Randers-Pehrson.
* See also "Contributing Authors", below.
*/
@@ -25,7 +25,7 @@ *
* This code is released under the libpng license.
*
- * libpng versions 1.0.7, July 1, 2000 through 1.6.31, July 27, 2017 are
+ * libpng versions 1.0.7, July 1, 2000 through 1.6.34, September 29, 2017 are
* Copyright (c) 2000-2002, 2004, 2006-2017 Glenn Randers-Pehrson, are
* derived from libpng-1.0.6, and are distributed according to the same
* disclaimer and license as libpng-1.0.6 with the following individuals
@@ -209,11 +209,11 @@ * ...
* 1.0.19 10 10019 10.so.0.19[.0]
* ...
- * 1.2.57 13 10257 12.so.0.57[.0]
+ * 1.2.59 13 10257 12.so.0.59[.0]
* ...
- * 1.5.28 15 10527 15.so.15.28[.0]
+ * 1.5.30 15 10527 15.so.15.30[.0]
* ...
- * 1.6.31 16 10631 16.so.16.31[.0]
+ * 1.6.34 16 10633 16.so.16.34[.0]
*
* Henceforth the source version will match the shared-library major
* and minor numbers; the shared-library major version number will be
@@ -241,13 +241,13 @@ * Y2K compliance in libpng:
* =========================
*
- * July 27, 2017
+ * September 29, 2017
*
* Since the PNG Development group is an ad-hoc body, we can't make
* an official declaration.
*
* This is your unofficial assurance that libpng from version 0.71 and
- * upward through 1.6.31 are Y2K compliant. It is my belief that
+ * upward through 1.6.34 are Y2K compliant. It is my belief that
* earlier versions were also Y2K compliant.
*
* Libpng only has two year fields. One is a 2-byte unsigned integer
@@ -309,8 +309,8 @@ */
/* Version information for png.h - this should match the version in png.c */
-#define PNG_LIBPNG_VER_STRING "1.6.31"
-#define PNG_HEADER_VERSION_STRING " libpng version 1.6.31 - July 27, 2017\n"
+#define PNG_LIBPNG_VER_STRING "1.6.34"
+#define PNG_HEADER_VERSION_STRING " libpng version 1.6.34 - September 29, 2017\n"
#define PNG_LIBPNG_VER_SONUM 16
#define PNG_LIBPNG_VER_DLLNUM 16
@@ -318,7 +318,7 @@ /* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
#define PNG_LIBPNG_VER_MAJOR 1
#define PNG_LIBPNG_VER_MINOR 6
-#define PNG_LIBPNG_VER_RELEASE 31
+#define PNG_LIBPNG_VER_RELEASE 34
/* This should match the numeric part of the final component of
* PNG_LIBPNG_VER_STRING, omitting any leading zero:
@@ -349,7 +349,7 @@ * version 1.0.0 was mis-numbered 100 instead of 10000). From
* version 1.0.1 it's xxyyzz, where x=major, y=minor, z=release
*/
-#define PNG_LIBPNG_VER 10631 /* 1.6.31 */
+#define PNG_LIBPNG_VER 10634 /* 1.6.34 */
/* Library configuration: these options cannot be changed after
* the library has been built.
@@ -459,7 +459,7 @@ extern "C" { /* This triggers a compiler error in png.c, if png.c and png.h
* do not agree upon the version number.
*/
-typedef char* png_libpng_version_1_6_31;
+typedef char* png_libpng_version_1_6_34;
/* Basic control structions. Read libpng-manual.txt or libpng.3 for more info.
*
@@ -2014,6 +2014,11 @@ PNG_EXPORT(246, png_uint_32, png_get_eXIf, (png_const_structrp png_ptr, png_inforp info_ptr, png_bytep *exif));
PNG_EXPORT(247, void, png_set_eXIf, (png_const_structrp png_ptr,
png_inforp info_ptr, const png_bytep exif));
+
+PNG_EXPORT(248, png_uint_32, png_get_eXIf_1, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr, png_uint_32 *num_exif, png_bytep *exif));
+PNG_EXPORT(249, void, png_set_eXIf_1, (png_const_structrp png_ptr,
+ png_inforp info_ptr, const png_uint_32 num_exif, const png_bytep exif));
#endif
#ifdef PNG_gAMA_SUPPORTED
@@ -2814,6 +2819,8 @@ typedef struct # define PNG_FORMAT_FLAG_AFIRST 0x20U /* alpha channel comes first */
#endif
+#define PNG_FORMAT_FLAG_ASSOCIATED_ALPHA 0x40U /* alpha channel is associated */
+
/* Commonly used formats have predefined macros.
*
* First the single byte (sRGB) formats:
@@ -3259,7 +3266,7 @@ PNG_EXPORT(244, int, png_set_option, (png_structrp png_ptr, int option, * one to use is one more than this.)
*/
#ifdef PNG_EXPORT_LAST_ORDINAL
- PNG_EXPORT_LAST_ORDINAL(247);
+ PNG_EXPORT_LAST_ORDINAL(249);
#endif
#ifdef __cplusplus
diff --git a/plugins/AdvaImg/src/LibPNG/pngconf.h b/plugins/AdvaImg/src/LibPNG/pngconf.h index 7c726ee149..af05e17554 100644 --- a/plugins/AdvaImg/src/LibPNG/pngconf.h +++ b/plugins/AdvaImg/src/LibPNG/pngconf.h @@ -1,7 +1,7 @@ /* pngconf.h - machine configurable file for libpng
*
- * libpng version 1.6.31, July 27, 2017
+ * libpng version 1.6.34, September 29, 2017
*
* Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
diff --git a/plugins/AdvaImg/src/LibPNG/pngget.c b/plugins/AdvaImg/src/LibPNG/pngget.c index 2779548336..c4a558b188 100644 --- a/plugins/AdvaImg/src/LibPNG/pngget.c +++ b/plugins/AdvaImg/src/LibPNG/pngget.c @@ -1,8 +1,8 @@ /* pngget.c - retrieval of values from info struct
*
- * Last changed in libpng 1.6.26 [October 20, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.32 [August 24, 2017]
+ * Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
*
@@ -778,11 +778,22 @@ png_uint_32 PNGAPI png_get_eXIf(png_const_structrp png_ptr, png_inforp info_ptr,
png_bytep *exif)
{
+ png_warning(png_ptr, "png_get_eXIf does not work; use png_get_eXIf_1");
+ PNG_UNUSED(info_ptr)
+ PNG_UNUSED(exif)
+ return 0;
+}
+
+png_uint_32 PNGAPI
+png_get_eXIf_1(png_const_structrp png_ptr, png_const_inforp info_ptr,
+ png_uint_32 *num_exif, png_bytep *exif)
+{
png_debug1(1, "in %s retrieval function", "eXIf");
if (png_ptr != NULL && info_ptr != NULL &&
(info_ptr->valid & PNG_INFO_eXIf) != 0 && exif != NULL)
{
+ *num_exif = info_ptr->num_exif;
*exif = info_ptr->exif;
return (PNG_INFO_eXIf);
}
diff --git a/plugins/AdvaImg/src/LibPNG/pnginfo.h b/plugins/AdvaImg/src/LibPNG/pnginfo.h index 61f4272267..366a16df64 100644 --- a/plugins/AdvaImg/src/LibPNG/pnginfo.h +++ b/plugins/AdvaImg/src/LibPNG/pnginfo.h @@ -186,8 +186,11 @@ defined(PNG_READ_BACKGROUND_SUPPORTED) #endif
#ifdef PNG_eXIf_SUPPORTED
- int num_exif;
+ int num_exif; /* Added at libpng-1.6.31 */
png_bytep exif;
+# ifdef PNG_READ_eXIf_SUPPORTED
+ png_bytep eXIf_buf; /* Added at libpng-1.6.32 */
+# endif
#endif
#ifdef PNG_hIST_SUPPORTED
diff --git a/plugins/AdvaImg/src/LibPNG/pnglibconf.h b/plugins/AdvaImg/src/LibPNG/pnglibconf.h index a62915e902..a9893acb40 100644 --- a/plugins/AdvaImg/src/LibPNG/pnglibconf.h +++ b/plugins/AdvaImg/src/LibPNG/pnglibconf.h @@ -1,10 +1,10 @@ -/* libpng 1.6.29 STANDARD API DEFINITION */
+/* libpng 1.6.34 STANDARD API DEFINITION */
/* pnglibconf.h - library build configuration */
-/* Libpng version 1.6.29 - March 16, 2017 */
+/* Libpng version 1.6.34 - September 29, 2017 */
-/* Copyright (c) 1998-2015 Glenn Randers-Pehrson */
+/* Copyright (c) 1998-2017 Glenn Randers-Pehrson */
/* This code is released under the libpng license. */
/* For conditions of distribution and use, see the disclaimer */
@@ -84,6 +84,7 @@ #define PNG_READ_USER_TRANSFORM_SUPPORTED
#define PNG_READ_bKGD_SUPPORTED
#define PNG_READ_cHRM_SUPPORTED
+#define PNG_READ_eXIf_SUPPORTED
#define PNG_READ_gAMA_SUPPORTED
#define PNG_READ_hIST_SUPPORTED
#define PNG_READ_iCCP_SUPPORTED
@@ -153,6 +154,7 @@ #define PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
#define PNG_WRITE_bKGD_SUPPORTED
#define PNG_WRITE_cHRM_SUPPORTED
+#define PNG_WRITE_eXIf_SUPPORTED
#define PNG_WRITE_gAMA_SUPPORTED
#define PNG_WRITE_hIST_SUPPORTED
#define PNG_WRITE_iCCP_SUPPORTED
@@ -170,6 +172,7 @@ #define PNG_WRITE_zTXt_SUPPORTED
#define PNG_bKGD_SUPPORTED
#define PNG_cHRM_SUPPORTED
+#define PNG_eXIf_SUPPORTED
#define PNG_gAMA_SUPPORTED
#define PNG_hIST_SUPPORTED
#define PNG_iCCP_SUPPORTED
diff --git a/plugins/AdvaImg/src/LibPNG/pngpread.c b/plugins/AdvaImg/src/LibPNG/pngpread.c index aaf5acd07f..705b61376c 100644 --- a/plugins/AdvaImg/src/LibPNG/pngpread.c +++ b/plugins/AdvaImg/src/LibPNG/pngpread.c @@ -1,8 +1,8 @@ /* pngpread.c - read a png file in push mode
*
- * Last changed in libpng 1.6.24 [August 4, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.32 [August 24, 2017]
+ * Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
*
@@ -189,6 +189,7 @@ png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr) png_crc_read(png_ptr, chunk_tag, 4);
png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
png_check_chunk_name(png_ptr, png_ptr->chunk_name);
+ png_check_chunk_length(png_ptr, png_ptr->push_length);
png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
}
diff --git a/plugins/AdvaImg/src/LibPNG/pngpriv.h b/plugins/AdvaImg/src/LibPNG/pngpriv.h index 8599652916..10d1fd69fc 100644 --- a/plugins/AdvaImg/src/LibPNG/pngpriv.h +++ b/plugins/AdvaImg/src/LibPNG/pngpriv.h @@ -1,7 +1,7 @@ /* pngpriv.h - private declarations for use inside libpng
*
- * Last changed in libpng 1.6.31 [July 27, 2017]
+ * Last changed in libpng 1.6.32 [August 24, 2017]
* Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -1143,6 +1143,11 @@ PNG_INTERNAL_FUNCTION(void,png_write_sRGB,(png_structrp png_ptr, int intent),PNG_EMPTY);
#endif
+#ifdef PNG_WRITE_eXIf_SUPPORTED
+PNG_INTERNAL_FUNCTION(void,png_write_eXIf,(png_structrp png_ptr,
+ png_bytep exif, int num_exif),PNG_EMPTY);
+#endif
+
#ifdef PNG_WRITE_iCCP_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_write_iCCP,(png_structrp png_ptr,
png_const_charp name, png_const_bytep profile), PNG_EMPTY);
@@ -1522,8 +1527,11 @@ PNG_INTERNAL_FUNCTION(void,png_handle_zTXt,(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
#endif
-PNG_INTERNAL_FUNCTION(void,png_check_chunk_name,(png_structrp png_ptr,
- png_uint_32 chunk_name),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_check_chunk_name,(png_const_structrp png_ptr,
+ const png_uint_32 chunk_name),PNG_EMPTY);
+
+PNG_INTERNAL_FUNCTION(void,png_check_chunk_length,(png_const_structrp png_ptr,
+ const png_uint_32 chunk_length),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_handle_unknown,(png_structrp png_ptr,
png_inforp info_ptr, png_uint_32 length, int keep),PNG_EMPTY);
diff --git a/plugins/AdvaImg/src/LibPNG/pngread.c b/plugins/AdvaImg/src/LibPNG/pngread.c index 8d7cf76c24..96e90d7104 100644 --- a/plugins/AdvaImg/src/LibPNG/pngread.c +++ b/plugins/AdvaImg/src/LibPNG/pngread.c @@ -1,7 +1,7 @@ /* pngread.c - read a PNG file
*
- * Last changed in libpng 1.6.31 [July 27, 2017]
+ * Last changed in libpng 1.6.33 [September 28, 2017]
* Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -175,6 +175,11 @@ png_read_info(png_structrp png_ptr, png_inforp info_ptr) png_handle_cHRM(png_ptr, info_ptr, length);
#endif
+#ifdef PNG_READ_eXIf_SUPPORTED
+ else if (chunk_name == png_eXIf)
+ png_handle_eXIf(png_ptr, info_ptr, length);
+#endif
+
#ifdef PNG_READ_gAMA_SUPPORTED
else if (chunk_name == png_gAMA)
png_handle_gAMA(png_ptr, info_ptr, length);
@@ -534,6 +539,7 @@ png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row) png_error(png_ptr, "Invalid attempt to read row data");
/* Fill the row with IDAT data: */
+ png_ptr->row_buf[0]=255; /* to force error if no data was found */
png_read_IDAT_data(png_ptr, png_ptr->row_buf, row_info.rowbytes + 1);
if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
@@ -842,6 +848,11 @@ png_read_end(png_structrp png_ptr, png_inforp info_ptr) png_handle_cHRM(png_ptr, info_ptr, length);
#endif
+#ifdef PNG_READ_eXIf_SUPPORTED
+ else if (chunk_name == png_eXIf)
+ png_handle_eXIf(png_ptr, info_ptr, length);
+#endif
+
#ifdef PNG_READ_gAMA_SUPPORTED
else if (chunk_name == png_gAMA)
png_handle_gAMA(png_ptr, info_ptr, length);
@@ -3748,7 +3759,13 @@ png_image_read_direct(png_voidp argument) mode = PNG_ALPHA_PNG;
output_gamma = PNG_DEFAULT_sRGB;
}
-
+
+ if ((change & PNG_FORMAT_FLAG_ASSOCIATED_ALPHA) != 0)
+ {
+ mode = PNG_ALPHA_OPTIMIZED;
+ change &= ~PNG_FORMAT_FLAG_ASSOCIATED_ALPHA;
+ }
+
/* If 'do_local_background' is set check for the presence of gamma
* correction; this is part of the work-round for the libpng bug
* described above.
@@ -3974,6 +3991,10 @@ png_image_read_direct(png_voidp argument) else if (do_local_compose != 0) /* internal error */
png_error(png_ptr, "png_image_read: alpha channel lost");
+ if ((format & PNG_FORMAT_FLAG_ASSOCIATED_ALPHA) != 0) {
+ info_format |= PNG_FORMAT_FLAG_ASSOCIATED_ALPHA;
+ }
+
if (info_ptr->bit_depth == 16)
info_format |= PNG_FORMAT_FLAG_LINEAR;
diff --git a/plugins/AdvaImg/src/LibPNG/pngrtran.c b/plugins/AdvaImg/src/LibPNG/pngrtran.c index 9679ba35df..eebd592f20 100644 --- a/plugins/AdvaImg/src/LibPNG/pngrtran.c +++ b/plugins/AdvaImg/src/LibPNG/pngrtran.c @@ -1,7 +1,7 @@ /* pngrtran.c - transforms the data in a row for PNG readers
*
- * Last changed in libpng 1.6.31 [July 27, 2017]
+ * Last changed in libpng 1.6.33 [September 28, 2017]
* Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -430,7 +430,7 @@ png_set_quantize(png_structrp png_ptr, png_colorp palette, int i;
png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr,
- (png_uint_32)((png_uint_32)num_palette * (sizeof (png_byte))));
+ (png_alloc_size_t)((png_uint_32)num_palette * (sizeof (png_byte))));
for (i = 0; i < num_palette; i++)
png_ptr->quantize_index[i] = (png_byte)i;
}
@@ -447,7 +447,7 @@ png_set_quantize(png_structrp png_ptr, png_colorp palette, /* Initialize an array to sort colors */
png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr,
- (png_uint_32)((png_uint_32)num_palette * (sizeof (png_byte))));
+ (png_alloc_size_t)((png_uint_32)num_palette * (sizeof (png_byte))));
/* Initialize the quantize_sort array */
for (i = 0; i < num_palette; i++)
@@ -581,9 +581,11 @@ png_set_quantize(png_structrp png_ptr, png_colorp palette, /* Initialize palette index arrays */
png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr,
- (png_uint_32)((png_uint_32)num_palette * (sizeof (png_byte))));
+ (png_alloc_size_t)((png_uint_32)num_palette *
+ (sizeof (png_byte))));
png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr,
- (png_uint_32)((png_uint_32)num_palette * (sizeof (png_byte))));
+ (png_alloc_size_t)((png_uint_32)num_palette *
+ (sizeof (png_byte))));
/* Initialize the sort array */
for (i = 0; i < num_palette; i++)
@@ -592,7 +594,7 @@ png_set_quantize(png_structrp png_ptr, png_colorp palette, png_ptr->palette_to_index[i] = (png_byte)i;
}
- hash = (png_dsortpp)png_calloc(png_ptr, (png_uint_32)(769 *
+ hash = (png_dsortpp)png_calloc(png_ptr, (png_alloc_size_t)(769 *
(sizeof (png_dsortp))));
num_new_palette = num_palette;
@@ -623,7 +625,7 @@ png_set_quantize(png_structrp png_ptr, png_colorp palette, {
t = (png_dsortp)png_malloc_warn(png_ptr,
- (png_uint_32)(sizeof (png_dsort)));
+ (png_alloc_size_t)(sizeof (png_dsort)));
if (t == NULL)
break;
@@ -748,9 +750,9 @@ png_set_quantize(png_structrp png_ptr, png_colorp palette, png_size_t num_entries = ((png_size_t)1 << total_bits);
png_ptr->palette_lookup = (png_bytep)png_calloc(png_ptr,
- (png_uint_32)(num_entries * (sizeof (png_byte))));
+ (png_alloc_size_t)(num_entries * (sizeof (png_byte))));
- distance = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_entries *
+ distance = (png_bytep)png_malloc(png_ptr, (png_alloc_size_t)(num_entries *
(sizeof (png_byte))));
memset(distance, 0xff, num_entries * (sizeof (png_byte)));
@@ -3322,7 +3324,7 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr) == png_ptr->trans_color.gray)
{
unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
- tmp |=
+ tmp |=
(unsigned int)(png_ptr->background.gray << shift);
*sp = (png_byte)(tmp & 0xff);
}
diff --git a/plugins/AdvaImg/src/LibPNG/pngrutil.c b/plugins/AdvaImg/src/LibPNG/pngrutil.c index afcebe40cb..ff639293aa 100644 --- a/plugins/AdvaImg/src/LibPNG/pngrutil.c +++ b/plugins/AdvaImg/src/LibPNG/pngrutil.c @@ -1,7 +1,7 @@ /* pngrutil.c - utilities to read a PNG file
*
- * Last changed in libpng 1.6.31 [July 27, 2017]
+ * Last changed in libpng 1.6.33 [September 28, 2017]
* Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -181,6 +181,9 @@ png_read_chunk_header(png_structrp png_ptr) /* Check to see if chunk name is valid. */
png_check_chunk_name(png_ptr, png_ptr->chunk_name);
+ /* Check for too-large chunk length */
+ png_check_chunk_length(png_ptr, length);
+
#ifdef PNG_IO_STATE_SUPPORTED
png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
#endif
@@ -311,6 +314,7 @@ png_read_buffer(png_structrp png_ptr, png_alloc_size_t new_size, int warn) if (buffer != NULL)
{
+ memset(buffer, 0, new_size); /* just in case */
png_ptr->read_buffer = buffer;
png_ptr->read_buffer_size = new_size;
}
@@ -670,6 +674,8 @@ png_decompress_chunk(png_structrp png_ptr, if (text != NULL)
{
+ memset(text, 0, buffer_size);
+
ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
png_ptr->read_buffer + prefix_size, &lzsize,
text + prefix_size, newlength);
@@ -733,9 +739,7 @@ png_decompress_chunk(png_structrp png_ptr, {
/* inflateReset failed, store the error message */
png_zstream_error(png_ptr, ret);
-
- if (ret == Z_STREAM_END)
- ret = PNG_UNEXPECTED_ZLIB_RETURN;
+ ret = PNG_UNEXPECTED_ZLIB_RETURN;
}
}
@@ -1377,11 +1381,13 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) * chunk is just ignored, so does not invalidate the color space. An
* alternative is to set the 'invalid' flags at the start of this routine
* and only clear them in they were not set before and all the tests pass.
- * The minimum 'deflate' stream is assumed to be just the 2 byte header and
- * 4 byte checksum. The keyword must be at least one character and there is
- * a terminator (0) byte and the compression method.
*/
- if (length < 9)
+
+ /* The keyword must be at least one character and there is a
+ * terminator (0) byte and the compression method byte, and the
+ * 'zlib' datastream is at least 11 bytes.
+ */
+ if (length < 14)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "too short");
@@ -1413,6 +1419,16 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) png_crc_read(png_ptr, (png_bytep)keyword, read_length);
length -= read_length;
+ /* The minimum 'zlib' stream is assumed to be just the 2 byte header,
+ * 5 bytes minimum 'deflate' stream, and the 4 byte checksum.
+ */
+ if (length < 11)
+ {
+ png_crc_finish(png_ptr, length);
+ png_chunk_benign_error(png_ptr, "too short");
+ return;
+ }
+
keyword_length = 0;
while (keyword_length < 80 && keyword_length < read_length &&
keyword[keyword_length] != 0)
@@ -1431,7 +1447,7 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) if (png_inflate_claim(png_ptr, png_iCCP) == Z_OK)
{
- Byte profile_header[132];
+ Byte profile_header[132]={0};
Byte local_buffer[PNG_INFLATE_BUF_SIZE];
png_alloc_size_t size = (sizeof profile_header);
@@ -1461,7 +1477,7 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) /* Now read the tag table; a variable size buffer is
* needed at this point, allocate one for the whole
* profile. The header check has already validated
- * that none of these stuff will overflow.
+ * that none of this stuff will overflow.
*/
const png_uint_32 tag_count = png_get_uint_32(
profile_header+128);
@@ -1568,19 +1584,11 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) return;
}
}
-
- else if (size > 0)
- errmsg = "truncated";
-
-#ifndef __COVERITY__
- else
+ if (errmsg == NULL)
errmsg = png_ptr->zstream.msg;
-#endif
}
-
/* else png_icc_check_tag_table output an error */
}
-
else /* profile truncated */
errmsg = png_ptr->zstream.msg;
}
@@ -2014,36 +2022,61 @@ void /* PRIVATE */ png_handle_eXIf(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
unsigned int i;
- png_bytep eXIf_buf;
png_debug(1, "in png_handle_eXIf");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
- else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_eXIf) != 0)
+ if (length < 2)
+ {
+ png_crc_finish(png_ptr, length);
+ png_chunk_benign_error(png_ptr, "too short");
+ return;
+ }
+
+ else if (info_ptr == NULL || (info_ptr->valid & PNG_INFO_eXIf) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "duplicate");
return;
}
- eXIf_buf = png_voidcast(png_bytep,
+ info_ptr->free_me |= PNG_FREE_EXIF;
+
+ info_ptr->eXIf_buf = png_voidcast(png_bytep,
png_malloc_warn(png_ptr, length));
+ if (info_ptr->eXIf_buf == NULL)
+ {
+ png_crc_finish(png_ptr, length);
+ png_chunk_benign_error(png_ptr, "out of memory");
+ return;
+ }
+
for (i = 0; i < length; i++)
{
png_byte buf[1];
png_crc_read(png_ptr, buf, 1);
- eXIf_buf[i] = buf[0];
+ info_ptr->eXIf_buf[i] = buf[0];
+ if (i == 1 && buf[0] != 'M' && buf[0] != 'I'
+ && info_ptr->eXIf_buf[0] != buf[0])
+ {
+ png_crc_finish(png_ptr, length);
+ png_chunk_benign_error(png_ptr, "incorrect byte-order specifier");
+ png_free(png_ptr, info_ptr->eXIf_buf);
+ info_ptr->eXIf_buf = NULL;
+ return;
+ }
}
if (png_crc_finish(png_ptr, 0) != 0)
return;
- info_ptr->num_exif = length;
+ png_set_eXIf_1(png_ptr, info_ptr, length, info_ptr->eXIf_buf);
- png_set_eXIf(png_ptr, info_ptr, eXIf_buf);
+ png_free(png_ptr, info_ptr->eXIf_buf);
+ info_ptr->eXIf_buf = NULL;
}
#endif
@@ -2624,23 +2657,28 @@ png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) {
png_text text;
- /* It worked; png_ptr->read_buffer now looks like a tEXt chunk except
- * for the extra compression type byte and the fact that it isn't
- * necessarily '\0' terminated.
- */
- buffer = png_ptr->read_buffer;
- buffer[uncompressed_length+(keyword_length+2)] = 0;
-
- text.compression = PNG_TEXT_COMPRESSION_zTXt;
- text.key = (png_charp)buffer;
- text.text = (png_charp)(buffer + keyword_length+2);
- text.text_length = uncompressed_length;
- text.itxt_length = 0;
- text.lang = NULL;
- text.lang_key = NULL;
-
- if (png_set_text_2(png_ptr, info_ptr, &text, 1) != 0)
- errmsg = "insufficient memory";
+ if (png_ptr->read_buffer == NULL)
+ errmsg="Read failure in png_handle_zTXt";
+ else
+ {
+ /* It worked; png_ptr->read_buffer now looks like a tEXt chunk
+ * except for the extra compression type byte and the fact that
+ * it isn't necessarily '\0' terminated.
+ */
+ buffer = png_ptr->read_buffer;
+ buffer[uncompressed_length+(keyword_length+2)] = 0;
+
+ text.compression = PNG_TEXT_COMPRESSION_zTXt;
+ text.key = (png_charp)buffer;
+ text.text = (png_charp)(buffer + keyword_length+2);
+ text.text_length = uncompressed_length;
+ text.itxt_length = 0;
+ text.lang = NULL;
+ text.lang_key = NULL;
+
+ if (png_set_text_2(png_ptr, info_ptr, &text, 1) != 0)
+ errmsg = "insufficient memory";
+ }
}
else
@@ -3076,20 +3114,58 @@ png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr, */
void /* PRIVATE */
-png_check_chunk_name(png_structrp png_ptr, png_uint_32 chunk_name)
+png_check_chunk_name(png_const_structrp png_ptr, const png_uint_32 chunk_name)
{
int i;
+ png_uint_32 cn=chunk_name;
png_debug(1, "in png_check_chunk_name");
for (i=1; i<=4; ++i)
{
- int c = chunk_name & 0xff;
+ int c = cn & 0xff;
if (c < 65 || c > 122 || (c > 90 && c < 97))
png_chunk_error(png_ptr, "invalid chunk type");
- chunk_name >>= 8;
+ cn >>= 8;
+ }
+}
+
+void /* PRIVATE */
+png_check_chunk_length(png_const_structrp png_ptr, const png_uint_32 length)
+{
+ png_alloc_size_t limit = PNG_UINT_31_MAX;
+
+# ifdef PNG_SET_USER_LIMITS_SUPPORTED
+ if (png_ptr->user_chunk_malloc_max > 0 &&
+ png_ptr->user_chunk_malloc_max < limit)
+ limit = png_ptr->user_chunk_malloc_max;
+# elif PNG_USER_CHUNK_MALLOC_MAX > 0
+ if (PNG_USER_CHUNK_MALLOC_MAX < limit)
+ limit = PNG_USER_CHUNK_MALLOC_MAX;
+# endif
+ if (png_ptr->chunk_name == png_IDAT)
+ {
+ png_alloc_size_t idat_limit = PNG_UINT_31_MAX;
+ size_t row_factor =
+ (png_ptr->width * png_ptr->channels * (png_ptr->bit_depth > 8? 2: 1)
+ + 1 + (png_ptr->interlaced? 6: 0));
+ if (png_ptr->height > PNG_UINT_32_MAX/row_factor)
+ idat_limit=PNG_UINT_31_MAX;
+ else
+ idat_limit = png_ptr->height * row_factor;
+ row_factor = row_factor > 32566? 32566 : row_factor;
+ idat_limit += 6 + 5*(idat_limit/row_factor+1); /* zlib+deflate overhead */
+ idat_limit=idat_limit < PNG_UINT_31_MAX? idat_limit : PNG_UINT_31_MAX;
+ limit = limit < idat_limit? idat_limit : limit;
+ }
+
+ if (length > limit)
+ {
+ png_debug2(0," length = %lu, limit = %lu",
+ (unsigned long)length,(unsigned long)limit);
+ png_chunk_error(png_ptr, "chunk data is too large");
}
}
diff --git a/plugins/AdvaImg/src/LibPNG/pngset.c b/plugins/AdvaImg/src/LibPNG/pngset.c index 7c6ed11a44..f3cb3ccfad 100644 --- a/plugins/AdvaImg/src/LibPNG/pngset.c +++ b/plugins/AdvaImg/src/LibPNG/pngset.c @@ -1,7 +1,7 @@ /* pngset.c - storage of image information into info struct
*
- * Last changed in libpng 1.6.30 [June 28, 2017]
+ * Last changed in libpng 1.6.32 [August 24, 2017]
* Copyright (c) 1998-2017 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -139,6 +139,15 @@ void PNGAPI png_set_eXIf(png_const_structrp png_ptr, png_inforp info_ptr,
const png_bytep eXIf_buf)
{
+ png_warning(png_ptr, "png_set_eXIf does not work; use png_set_eXIf_1");
+ PNG_UNUSED(info_ptr)
+ PNG_UNUSED(eXIf_buf)
+}
+
+void PNGAPI
+png_set_eXIf_1(png_const_structrp png_ptr, png_inforp info_ptr,
+ const png_uint_32 num_exif, const png_bytep eXIf_buf)
+{
int i;
png_debug1(1, "in %s storage function", "eXIf");
@@ -146,7 +155,13 @@ png_set_eXIf(png_const_structrp png_ptr, png_inforp info_ptr, if (png_ptr == NULL || info_ptr == NULL)
return;
- png_free_data(png_ptr, info_ptr, PNG_FREE_EXIF, 0);
+ if (info_ptr->exif)
+ {
+ png_free(png_ptr, info_ptr->exif);
+ info_ptr->exif = NULL;
+ }
+
+ info_ptr->num_exif = num_exif;
info_ptr->exif = png_voidcast(png_bytep, png_malloc_warn(png_ptr,
info_ptr->num_exif));
@@ -154,13 +169,12 @@ png_set_eXIf(png_const_structrp png_ptr, png_inforp info_ptr, if (info_ptr->exif == NULL)
{
png_warning(png_ptr, "Insufficient memory for eXIf chunk data");
-
return;
}
info_ptr->free_me |= PNG_FREE_EXIF;
- for (i = 0; i < info_ptr->num_exif; i++)
+ for (i = 0; i < (int) info_ptr->num_exif; i++)
info_ptr->exif[i] = eXIf_buf[i];
info_ptr->valid |= PNG_INFO_eXIf;
@@ -1388,6 +1402,7 @@ png_set_keep_unknown_chunks(png_structrp png_ptr, int keep, static PNG_CONST png_byte chunks_to_ignore[] = {
98, 75, 71, 68, '\0', /* bKGD */
99, 72, 82, 77, '\0', /* cHRM */
+ 101, 88, 73, 102, '\0', /* eXIf */
103, 65, 77, 65, '\0', /* gAMA */
104, 73, 83, 84, '\0', /* hIST */
105, 67, 67, 80, '\0', /* iCCP */
diff --git a/plugins/AdvaImg/src/LibPNG/pngstruct.h b/plugins/AdvaImg/src/LibPNG/pngstruct.h index e775080cc4..968764b296 100644 --- a/plugins/AdvaImg/src/LibPNG/pngstruct.h +++ b/plugins/AdvaImg/src/LibPNG/pngstruct.h @@ -1,7 +1,7 @@ /* pngstruct.h - header file for PNG reference library
*
- * Last changed in libpng 1.6.28 [January 5, 2017]
+ * Last changed in libpng 1.6.32 [August 24, 2017]
* Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -479,8 +479,5 @@ struct png_struct_def png_colorspace colorspace;
#endif
#endif
-
-/* New member added in libpng-1.6.31 */
- int num_exif;
};
#endif /* PNGSTRUCT_H */
diff --git a/plugins/AdvaImg/src/LibPNG/pngtest.c b/plugins/AdvaImg/src/LibPNG/pngtest.c index feef2e3569..e56cbaeefa 100644 --- a/plugins/AdvaImg/src/LibPNG/pngtest.c +++ b/plugins/AdvaImg/src/LibPNG/pngtest.c @@ -1,8 +1,8 @@ /* pngtest.c - a simple test program to test libpng
*
- * Last changed in libpng 1.6.26 [October 20, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.32 [August 24, 2017]
+ * Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
*
@@ -144,6 +144,7 @@ tIME_to_str(png_structp png_ptr, png_charp ts, png_const_timep t) static int verbose = 0;
static int strict = 0;
static int relaxed = 0;
+static int xfail = 0;
static int unsupported_chunks = 0; /* chunk unsupported by libpng in input */
static int error_count = 0; /* count calls to png_error */
static int warning_count = 0; /* count calls to png_warning */
@@ -463,7 +464,7 @@ pngtest_warning(png_structp png_ptr, png_const_charp message) if (test != NULL && test->file_name != NULL)
name = test->file_name;
- fprintf(STDERR, "%s: libpng warning: %s\n", name, message);
+ fprintf(STDERR, "\n%s: libpng warning: %s\n", name, message);
}
/* This is the default error handling function. Note that replacements for
@@ -936,8 +937,12 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname) fprintf(STDERR, "%s -> %s: libpng read error\n", inname, outname);
png_free(read_ptr, row_buf);
row_buf = NULL;
+ if (verbose != 0)
+ fprintf(STDERR, " destroy read structs\n");
png_destroy_read_struct(&read_ptr, &read_info_ptr, &end_info_ptr);
#ifdef PNG_WRITE_SUPPORTED
+ if (verbose != 0)
+ fprintf(STDERR, " destroy write structs\n");
png_destroy_info_struct(write_ptr, &write_end_info_ptr);
png_destroy_write_struct(&write_ptr, &write_info_ptr);
#endif
@@ -952,11 +957,13 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname) if (setjmp(png_jmpbuf(write_ptr)))
{
fprintf(STDERR, "%s -> %s: libpng write error\n", inname, outname);
+ if (verbose != 0)
+ fprintf(STDERR, " destroying read structs\n");
png_destroy_read_struct(&read_ptr, &read_info_ptr, &end_info_ptr);
+ if (verbose != 0)
+ fprintf(STDERR, " destroying write structs\n");
png_destroy_info_struct(write_ptr, &write_end_info_ptr);
-#ifdef PNG_WRITE_SUPPORTED
png_destroy_write_struct(&write_ptr, &write_info_ptr);
-#endif
FCLOSE(fpin);
FCLOSE(fpout);
return (1);
@@ -1192,12 +1199,20 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname) }
}
#endif
-#ifdef PNG_eXIf_SUPPORTED
+#ifdef PNG_READ_eXIf_SUPPORTED
{
- png_bytep exif;
+ png_bytep exif=NULL;
+ png_uint_32 exif_length;
- if (png_get_eXIf(read_ptr, read_info_ptr, &exif) != 0)
- png_set_eXIf(write_ptr, write_info_ptr, exif);
+ if (png_get_eXIf_1(read_ptr, read_info_ptr, &exif_length, &exif) != 0)
+ {
+ if (exif_length > 1)
+ fprintf(STDERR," eXIf type %c%c, %lu bytes\n",exif[0],exif[1],
+ (unsigned long)exif_length);
+# ifdef PNG_WRITE_eXIf_SUPPORTED
+ png_set_eXIf_1(write_ptr, write_info_ptr, exif_length, exif);
+# endif
+ }
}
#endif
#ifdef PNG_hIST_SUPPORTED
@@ -1310,10 +1325,10 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname) {
int i;
- printf("\n");
+ fprintf(STDERR,"\n");
for (i=0; i<num_text; i++)
{
- printf(" Text compression[%d]=%d\n",
+ fprintf(STDERR," Text compression[%d]=%d\n",
i, text_ptr[i].compression);
}
}
@@ -1406,6 +1421,10 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname) write_chunks(write_ptr, before_IDAT); /* after PLTE */
+ png_write_info(write_ptr, write_end_info_ptr);
+
+ write_chunks(write_ptr, after_IDAT); /* after IDAT */
+
#ifdef PNG_COMPRESSION_COMPAT
/* Test the 'compatibility' setting here, if it is available. */
png_set_compression(write_ptr, PNG_COMPRESSION_COMPAT);
@@ -1526,10 +1545,10 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname) {
int i;
- printf("\n");
+ fprintf(STDERR,"\n");
for (i=0; i<num_text; i++)
{
- printf(" Text compression[%d]=%d\n",
+ fprintf(STDERR," Text compression[%d]=%d\n",
i, text_ptr[i].compression);
}
}
@@ -1538,12 +1557,20 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname) }
}
#endif
-#ifdef PNG_eXIf_SUPPORTED
+#ifdef PNG_READ_eXIf_SUPPORTED
{
- png_bytep exif;
+ png_bytep exif=NULL;
+ png_uint_32 exif_length;
- if (png_get_eXIf(read_ptr, end_info_ptr, &exif) != 0)
- png_set_eXIf(write_ptr, write_end_info_ptr, exif);
+ if (png_get_eXIf_1(read_ptr, end_info_ptr, &exif_length, &exif) != 0)
+ {
+ if (exif_length > 1)
+ fprintf(STDERR," eXIf type %c%c, %lu bytes\n",exif[0],exif[1],
+ (unsigned long)exif_length);
+# ifdef PNG_WRITE_eXIf_SUPPORTED
+ png_set_eXIf_1(write_ptr, write_end_info_ptr, exif_length, exif);
+# endif
+ }
}
#endif
#ifdef PNG_tIME_SUPPORTED
@@ -1861,6 +1888,7 @@ main(int argc, char *argv[]) inname = argv[2];
strict++;
relaxed = 0;
+ multiple=1;
}
else if (strcmp(argv[1], "--relaxed") == 0)
@@ -1870,6 +1898,17 @@ main(int argc, char *argv[]) inname = argv[2];
strict = 0;
relaxed++;
+ multiple=1;
+ }
+ else if (strcmp(argv[1], "--xfail") == 0)
+ {
+ status_dots_requested = 0;
+ verbose = 1;
+ inname = argv[2];
+ strict = 0;
+ xfail++;
+ relaxed++;
+ multiple=1;
}
else
@@ -1927,8 +1966,13 @@ main(int argc, char *argv[]) else
{
- fprintf(STDERR, " FAIL\n");
- ierror += kerror;
+ if (xfail)
+ fprintf(STDERR, " XFAIL\n");
+ else
+ {
+ fprintf(STDERR, " FAIL\n");
+ ierror += kerror;
+ }
}
#if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
if (allocation_now != current_allocation)
@@ -2016,8 +2060,13 @@ main(int argc, char *argv[]) #endif
}
- fprintf(STDERR, " FAIL\n");
- ierror += kerror;
+ if (xfail)
+ fprintf(STDERR, " XFAIL\n");
+ else
+ {
+ fprintf(STDERR, " FAIL\n");
+ ierror += kerror;
+ }
}
#if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
if (allocation_now != current_allocation)
@@ -2104,4 +2153,4 @@ main(void) #endif
/* Generate a compiler error if there is an old png.h in the search path. */
-typedef png_libpng_version_1_6_31 Your_png_h_is_not_version_1_6_31;
+typedef png_libpng_version_1_6_34 Your_png_h_is_not_version_1_6_34;
diff --git a/plugins/AdvaImg/src/LibPNG/pngtrans.c b/plugins/AdvaImg/src/LibPNG/pngtrans.c index 06c3a1c141..1dad1d7a5e 100644 --- a/plugins/AdvaImg/src/LibPNG/pngtrans.c +++ b/plugins/AdvaImg/src/LibPNG/pngtrans.c @@ -1,7 +1,7 @@ /* pngtrans.c - transforms the data in a row (used by both readers and writers)
*
- * Last changed in libpng 1.6.30 [June 28, 2017]
+ * Last changed in libpng 1.6.33 [September 28, 2017]
* Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -609,7 +609,7 @@ png_do_strip_channel(png_row_infop row_info, png_bytep row, int at_start) return; /* The filler channel has gone already */
/* Fix the rowbytes value. */
- row_info->rowbytes = (unsigned int)(dp-row);
+ row_info->rowbytes = (png_size_t)(dp-row);
}
#endif
@@ -708,7 +708,7 @@ png_do_check_palette_indexes(png_structrp png_ptr, png_row_infop row_info) * forms produced on either GCC or MSVC.
*/
int padding = PNG_PADBITS(row_info->pixel_depth, row_info->width);
- png_bytep rp = png_ptr->row_buf + row_info->rowbytes;
+ png_bytep rp = png_ptr->row_buf + row_info->rowbytes - 1;
switch (row_info->bit_depth)
{
diff --git a/plugins/AdvaImg/src/LibPNG/pngwrite.c b/plugins/AdvaImg/src/LibPNG/pngwrite.c index c4a328fdf2..1eefbe686e 100644 --- a/plugins/AdvaImg/src/LibPNG/pngwrite.c +++ b/plugins/AdvaImg/src/LibPNG/pngwrite.c @@ -1,7 +1,7 @@ /* pngwrite.c - general routines to write a PNG file
*
- * Last changed in libpng 1.6.31 [July 27, 2017]
+ * Last changed in libpng 1.6.32 [August 24, 2017]
* Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -237,6 +237,11 @@ png_write_info(png_structrp png_ptr, png_const_inforp info_ptr) png_write_bKGD(png_ptr, &(info_ptr->background), info_ptr->color_type);
#endif
+#ifdef PNG_WRITE_eXIf_SUPPORTED
+ if ((info_ptr->valid & PNG_INFO_eXIf) != 0)
+ png_write_eXIf(png_ptr, info_ptr->exif, info_ptr->num_exif);
+#endif
+
#ifdef PNG_WRITE_hIST_SUPPORTED
if ((info_ptr->valid & PNG_INFO_hIST) != 0)
png_write_hIST(png_ptr, info_ptr->hist, info_ptr->num_palette);
@@ -432,6 +437,12 @@ png_write_end(png_structrp png_ptr, png_inforp info_ptr) }
}
#endif
+
+#ifdef PNG_WRITE_eXIf_SUPPORTED
+ if ((info_ptr->valid & PNG_INFO_eXIf) != 0)
+ png_write_eXIf(png_ptr, info_ptr->exif, info_ptr->num_exif);
+#endif
+
#ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
write_unknown_chunks(png_ptr, info_ptr, PNG_AFTER_IDAT);
#endif
@@ -1929,7 +1940,7 @@ png_image_write_main(png_voidp argument) int colormap = (format & PNG_FORMAT_FLAG_COLORMAP);
int linear = !colormap && (format & PNG_FORMAT_FLAG_LINEAR); /* input */
int alpha = !colormap && (format & PNG_FORMAT_FLAG_ALPHA);
- int write_16bit = linear && !colormap && (display->convert_to_8bit == 0);
+ int write_16bit = linear && (display->convert_to_8bit == 0);
# ifdef PNG_BENIGN_ERRORS_SUPPORTED
/* Make sure we error out on any bad situation */
diff --git a/plugins/AdvaImg/src/LibPNG/pngwutil.c b/plugins/AdvaImg/src/LibPNG/pngwutil.c index 7a09b35e8c..d536c9e6fb 100644 --- a/plugins/AdvaImg/src/LibPNG/pngwutil.c +++ b/plugins/AdvaImg/src/LibPNG/pngwutil.c @@ -1,8 +1,8 @@ /* pngwutil.c - utilities to write a PNG file
*
- * Last changed in libpng 1.6.26 [October 20, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.32 [August 24, 2017]
+ * Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
*
@@ -1479,24 +1479,15 @@ void /* PRIVATE */ png_write_eXIf(png_structrp png_ptr, png_bytep exif, int num_exif)
{
int i;
- png_byte buf[3];
+ png_byte buf[1];
png_debug(1, "in png_write_eXIf");
- if (num_exif > (int)png_ptr->num_exif)
- {
- png_debug2(3, "num_exif = %d, png_ptr->num_exif = %d", num_exif,
- png_ptr->num_exif);
-
- png_warning(png_ptr, "Invalid number of exif bytes specified");
- return;
- }
-
png_write_chunk_header(png_ptr, png_eXIf, (png_uint_32)(num_exif));
for (i = 0; i < num_exif; i++)
{
- buf[i] = exif[i];
+ buf[0] = exif[i];
png_write_chunk_data(png_ptr, buf, (png_size_t)1);
}
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