diff options
Diffstat (limited to 'plugins/FreeImage/Source/LibPNG/png.c')
| -rw-r--r-- | plugins/FreeImage/Source/LibPNG/png.c | 2870 |
1 files changed, 0 insertions, 2870 deletions
diff --git a/plugins/FreeImage/Source/LibPNG/png.c b/plugins/FreeImage/Source/LibPNG/png.c deleted file mode 100644 index 0df53a62af..0000000000 --- a/plugins/FreeImage/Source/LibPNG/png.c +++ /dev/null @@ -1,2870 +0,0 @@ -
-/* png.c - location for general purpose libpng functions
- *
- * Last changed in libpng 1.5.7 [December 15, 2011]
- * Copyright (c) 1998-2011 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.)
- *
- * This code is released under the libpng license.
- * For conditions of distribution and use, see the disclaimer
- * and license in png.h
- */
-
-#include "pngpriv.h"
-
-/* Generate a compiler error if there is an old png.h in the search path. */
-typedef png_libpng_version_1_5_9 Your_png_h_is_not_version_1_5_9;
-
-/* Tells libpng that we have already handled the first "num_bytes" bytes
- * of the PNG file signature. If the PNG data is embedded into another
- * stream we can set num_bytes = 8 so that libpng will not attempt to read
- * or write any of the magic bytes before it starts on the IHDR.
- */
-
-#ifdef PNG_READ_SUPPORTED
-void PNGAPI
-png_set_sig_bytes(png_structp png_ptr, int num_bytes)
-{
- png_debug(1, "in png_set_sig_bytes");
-
- if (png_ptr == NULL)
- return;
-
- if (num_bytes > 8)
- png_error(png_ptr, "Too many bytes for PNG signature");
-
- png_ptr->sig_bytes = (png_byte)(num_bytes < 0 ? 0 : num_bytes);
-}
-
-/* Checks whether the supplied bytes match the PNG signature. We allow
- * checking less than the full 8-byte signature so that those apps that
- * already read the first few bytes of a file to determine the file type
- * can simply check the remaining bytes for extra assurance. Returns
- * an integer less than, equal to, or greater than zero if sig is found,
- * respectively, to be less than, to match, or be greater than the correct
- * PNG signature (this is the same behavior as strcmp, memcmp, etc).
- */
-int PNGAPI
-png_sig_cmp(png_const_bytep sig, png_size_t start, png_size_t num_to_check)
-{
- png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
-
- if (num_to_check > 8)
- num_to_check = 8;
-
- else if (num_to_check < 1)
- return (-1);
-
- if (start > 7)
- return (-1);
-
- if (start + num_to_check > 8)
- num_to_check = 8 - start;
-
- return ((int)(png_memcmp(&sig[start], &png_signature[start], num_to_check)));
-}
-
-#endif /* PNG_READ_SUPPORTED */
-
-#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
-/* Function to allocate memory for zlib */
-PNG_FUNCTION(voidpf /* PRIVATE */,
-png_zalloc,(voidpf png_ptr, uInt items, uInt size),PNG_ALLOCATED)
-{
- png_voidp ptr;
- png_structp p=(png_structp)png_ptr;
- png_uint_32 save_flags=p->flags;
- png_alloc_size_t num_bytes;
-
- if (png_ptr == NULL)
- return (NULL);
-
- if (items > PNG_UINT_32_MAX/size)
- {
- png_warning (p, "Potential overflow in png_zalloc()");
- return (NULL);
- }
- num_bytes = (png_alloc_size_t)items * size;
-
- p->flags|=PNG_FLAG_MALLOC_NULL_MEM_OK;
- ptr = (png_voidp)png_malloc((png_structp)png_ptr, num_bytes);
- p->flags=save_flags;
-
- return ((voidpf)ptr);
-}
-
-/* Function to free memory for zlib */
-void /* PRIVATE */
-png_zfree(voidpf png_ptr, voidpf ptr)
-{
- png_free((png_structp)png_ptr, (png_voidp)ptr);
-}
-
-/* Reset the CRC variable to 32 bits of 1's. Care must be taken
- * in case CRC is > 32 bits to leave the top bits 0.
- */
-void /* PRIVATE */
-png_reset_crc(png_structp png_ptr)
-{
- /* The cast is safe because the crc is a 32 bit value. */
- png_ptr->crc = (png_uint_32)crc32(0, Z_NULL, 0);
-}
-
-/* Calculate the CRC over a section of data. We can only pass as
- * much data to this routine as the largest single buffer size. We
- * also check that this data will actually be used before going to the
- * trouble of calculating it.
- */
-void /* PRIVATE */
-png_calculate_crc(png_structp png_ptr, png_const_bytep ptr, png_size_t length)
-{
- int need_crc = 1;
-
- if (PNG_CHUNK_ANCILLIARY(png_ptr->chunk_name))
- {
- if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
- (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
- need_crc = 0;
- }
-
- else /* critical */
- {
- if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
- need_crc = 0;
- }
-
- /* 'uLong' is defined as unsigned long, this means that on some systems it is
- * a 64 bit value. crc32, however, returns 32 bits so the following cast is
- * safe. 'uInt' may be no more than 16 bits, so it is necessary to perform a
- * loop here.
- */
- if (need_crc && length > 0)
- {
- uLong crc = png_ptr->crc; /* Should never issue a warning */
-
- do
- {
- uInt safeLength = (uInt)length;
- if (safeLength == 0)
- safeLength = (uInt)-1; /* evil, but safe */
-
- crc = crc32(crc, ptr, safeLength);
-
- /* The following should never issue compiler warnings, if they do the
- * target system has characteristics that will probably violate other
- * assumptions within the libpng code.
- */
- ptr += safeLength;
- length -= safeLength;
- }
- while (length > 0);
-
- /* And the following is always safe because the crc is only 32 bits. */
- png_ptr->crc = (png_uint_32)crc;
- }
-}
-
-/* Check a user supplied version number, called from both read and write
- * functions that create a png_struct
- */
-int
-png_user_version_check(png_structp png_ptr, png_const_charp user_png_ver)
-{
- if (user_png_ver)
- {
- int i = 0;
-
- do
- {
- if (user_png_ver[i] != png_libpng_ver[i])
- png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
- } while (png_libpng_ver[i++]);
- }
-
- else
- png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
-
- if (png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH)
- {
- /* Libpng 0.90 and later are binary incompatible with libpng 0.89, so
- * we must recompile any applications that use any older library version.
- * For versions after libpng 1.0, we will be compatible, so we need
- * only check the first digit.
- */
- if (user_png_ver == NULL || user_png_ver[0] != png_libpng_ver[0] ||
- (user_png_ver[0] == '1' && user_png_ver[2] != png_libpng_ver[2]) ||
- (user_png_ver[0] == '0' && user_png_ver[2] < '9'))
- {
-#ifdef PNG_WARNINGS_SUPPORTED
- size_t pos = 0;
- char m[128];
-
- pos = png_safecat(m, sizeof m, pos, "Application built with libpng-");
- pos = png_safecat(m, sizeof m, pos, user_png_ver);
- pos = png_safecat(m, sizeof m, pos, " but running with ");
- pos = png_safecat(m, sizeof m, pos, png_libpng_ver);
-
- png_warning(png_ptr, m);
-#endif
-
-#ifdef PNG_ERROR_NUMBERS_SUPPORTED
- png_ptr->flags = 0;
-#endif
-
- return 0;
- }
- }
-
- /* Success return. */
- return 1;
-}
-
-/* Allocate the memory for an info_struct for the application. We don't
- * really need the png_ptr, but it could potentially be useful in the
- * future. This should be used in favour of malloc(png_sizeof(png_info))
- * and png_info_init() so that applications that want to use a shared
- * libpng don't have to be recompiled if png_info changes size.
- */
-PNG_FUNCTION(png_infop,PNGAPI
-png_create_info_struct,(png_structp png_ptr),PNG_ALLOCATED)
-{
- png_infop info_ptr;
-
- png_debug(1, "in png_create_info_struct");
-
- if (png_ptr == NULL)
- return (NULL);
-
-#ifdef PNG_USER_MEM_SUPPORTED
- info_ptr = (png_infop)png_create_struct_2(PNG_STRUCT_INFO,
- png_ptr->malloc_fn, png_ptr->mem_ptr);
-#else
- info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);
-#endif
- if (info_ptr != NULL)
- png_info_init_3(&info_ptr, png_sizeof(png_info));
-
- return (info_ptr);
-}
-
-/* This function frees the memory associated with a single info struct.
- * Normally, one would use either png_destroy_read_struct() or
- * png_destroy_write_struct() to free an info struct, but this may be
- * useful for some applications.
- */
-void PNGAPI
-png_destroy_info_struct(png_structp png_ptr, png_infopp info_ptr_ptr)
-{
- png_infop info_ptr = NULL;
-
- png_debug(1, "in png_destroy_info_struct");
-
- if (png_ptr == NULL)
- return;
-
- if (info_ptr_ptr != NULL)
- info_ptr = *info_ptr_ptr;
-
- if (info_ptr != NULL)
- {
- png_info_destroy(png_ptr, info_ptr);
-
-#ifdef PNG_USER_MEM_SUPPORTED
- png_destroy_struct_2((png_voidp)info_ptr, png_ptr->free_fn,
- png_ptr->mem_ptr);
-#else
- png_destroy_struct((png_voidp)info_ptr);
-#endif
- *info_ptr_ptr = NULL;
- }
-}
-
-/* Initialize the info structure. This is now an internal function (0.89)
- * and applications using it are urged to use png_create_info_struct()
- * instead.
- */
-
-void PNGAPI
-png_info_init_3(png_infopp ptr_ptr, png_size_t png_info_struct_size)
-{
- png_infop info_ptr = *ptr_ptr;
-
- png_debug(1, "in png_info_init_3");
-
- if (info_ptr == NULL)
- return;
-
- if (png_sizeof(png_info) > png_info_struct_size)
- {
- png_destroy_struct(info_ptr);
- info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);
- *ptr_ptr = info_ptr;
- }
-
- /* Set everything to 0 */
- png_memset(info_ptr, 0, png_sizeof(png_info));
-}
-
-void PNGAPI
-png_data_freer(png_structp png_ptr, png_infop info_ptr,
- int freer, png_uint_32 mask)
-{
- png_debug(1, "in png_data_freer");
-
- if (png_ptr == NULL || info_ptr == NULL)
- return;
-
- if (freer == PNG_DESTROY_WILL_FREE_DATA)
- info_ptr->free_me |= mask;
-
- else if (freer == PNG_USER_WILL_FREE_DATA)
- info_ptr->free_me &= ~mask;
-
- else
- png_warning(png_ptr,
- "Unknown freer parameter in png_data_freer");
-}
-
-void PNGAPI
-png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
- int num)
-{
- png_debug(1, "in png_free_data");
-
- if (png_ptr == NULL || info_ptr == NULL)
- return;
-
-#ifdef PNG_TEXT_SUPPORTED
- /* Free text item num or (if num == -1) all text items */
- if ((mask & PNG_FREE_TEXT) & info_ptr->free_me)
- {
- if (num != -1)
- {
- if (info_ptr->text && info_ptr->text[num].key)
- {
- png_free(png_ptr, info_ptr->text[num].key);
- info_ptr->text[num].key = NULL;
- }
- }
-
- else
- {
- int i;
- for (i = 0; i < info_ptr->num_text; i++)
- png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, i);
- png_free(png_ptr, info_ptr->text);
- info_ptr->text = NULL;
- info_ptr->num_text=0;
- }
- }
-#endif
-
-#ifdef PNG_tRNS_SUPPORTED
- /* Free any tRNS entry */
- if ((mask & PNG_FREE_TRNS) & info_ptr->free_me)
- {
- png_free(png_ptr, info_ptr->trans_alpha);
- info_ptr->trans_alpha = NULL;
- info_ptr->valid &= ~PNG_INFO_tRNS;
- }
-#endif
-
-#ifdef PNG_sCAL_SUPPORTED
- /* Free any sCAL entry */
- if ((mask & PNG_FREE_SCAL) & info_ptr->free_me)
- {
- png_free(png_ptr, info_ptr->scal_s_width);
- png_free(png_ptr, info_ptr->scal_s_height);
- info_ptr->scal_s_width = NULL;
- info_ptr->scal_s_height = NULL;
- info_ptr->valid &= ~PNG_INFO_sCAL;
- }
-#endif
-
-#ifdef PNG_pCAL_SUPPORTED
- /* Free any pCAL entry */
- if ((mask & PNG_FREE_PCAL) & info_ptr->free_me)
- {
- png_free(png_ptr, info_ptr->pcal_purpose);
- png_free(png_ptr, info_ptr->pcal_units);
- info_ptr->pcal_purpose = NULL;
- info_ptr->pcal_units = NULL;
- if (info_ptr->pcal_params != NULL)
- {
- int i;
- for (i = 0; i < (int)info_ptr->pcal_nparams; i++)
- {
- png_free(png_ptr, info_ptr->pcal_params[i]);
- info_ptr->pcal_params[i] = NULL;
- }
- png_free(png_ptr, info_ptr->pcal_params);
- info_ptr->pcal_params = NULL;
- }
- info_ptr->valid &= ~PNG_INFO_pCAL;
- }
-#endif
-
-#ifdef PNG_iCCP_SUPPORTED
- /* Free any iCCP entry */
- if ((mask & PNG_FREE_ICCP) & info_ptr->free_me)
- {
- png_free(png_ptr, info_ptr->iccp_name);
- png_free(png_ptr, info_ptr->iccp_profile);
- info_ptr->iccp_name = NULL;
- info_ptr->iccp_profile = NULL;
- info_ptr->valid &= ~PNG_INFO_iCCP;
- }
-#endif
-
-#ifdef PNG_sPLT_SUPPORTED
- /* Free a given sPLT entry, or (if num == -1) all sPLT entries */
- if ((mask & PNG_FREE_SPLT) & info_ptr->free_me)
- {
- if (num != -1)
- {
- if (info_ptr->splt_palettes)
- {
- png_free(png_ptr, info_ptr->splt_palettes[num].name);
- png_free(png_ptr, info_ptr->splt_palettes[num].entries);
- info_ptr->splt_palettes[num].name = NULL;
- info_ptr->splt_palettes[num].entries = NULL;
- }
- }
-
- else
- {
- if (info_ptr->splt_palettes_num)
- {
- int i;
- for (i = 0; i < (int)info_ptr->splt_palettes_num; i++)
- png_free_data(png_ptr, info_ptr, PNG_FREE_SPLT, i);
-
- png_free(png_ptr, info_ptr->splt_palettes);
- info_ptr->splt_palettes = NULL;
- info_ptr->splt_palettes_num = 0;
- }
- info_ptr->valid &= ~PNG_INFO_sPLT;
- }
- }
-#endif
-
-#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
- if (png_ptr->unknown_chunk.data)
- {
- png_free(png_ptr, png_ptr->unknown_chunk.data);
- png_ptr->unknown_chunk.data = NULL;
- }
-
- if ((mask & PNG_FREE_UNKN) & info_ptr->free_me)
- {
- if (num != -1)
- {
- if (info_ptr->unknown_chunks)
- {
- png_free(png_ptr, info_ptr->unknown_chunks[num].data);
- info_ptr->unknown_chunks[num].data = NULL;
- }
- }
-
- else
- {
- int i;
-
- if (info_ptr->unknown_chunks_num)
- {
- for (i = 0; i < info_ptr->unknown_chunks_num; i++)
- png_free_data(png_ptr, info_ptr, PNG_FREE_UNKN, i);
-
- png_free(png_ptr, info_ptr->unknown_chunks);
- info_ptr->unknown_chunks = NULL;
- info_ptr->unknown_chunks_num = 0;
- }
- }
- }
-#endif
-
-#ifdef PNG_hIST_SUPPORTED
- /* Free any hIST entry */
- if ((mask & PNG_FREE_HIST) & info_ptr->free_me)
- {
- png_free(png_ptr, info_ptr->hist);
- info_ptr->hist = NULL;
- info_ptr->valid &= ~PNG_INFO_hIST;
- }
-#endif
-
- /* Free any PLTE entry that was internally allocated */
- if ((mask & PNG_FREE_PLTE) & info_ptr->free_me)
- {
- png_zfree(png_ptr, info_ptr->palette);
- info_ptr->palette = NULL;
- info_ptr->valid &= ~PNG_INFO_PLTE;
- info_ptr->num_palette = 0;
- }
-
-#ifdef PNG_INFO_IMAGE_SUPPORTED
- /* Free any image bits attached to the info structure */
- if ((mask & PNG_FREE_ROWS) & info_ptr->free_me)
- {
- if (info_ptr->row_pointers)
- {
- int row;
- for (row = 0; row < (int)info_ptr->height; row++)
- {
- png_free(png_ptr, info_ptr->row_pointers[row]);
- info_ptr->row_pointers[row] = NULL;
- }
- png_free(png_ptr, info_ptr->row_pointers);
- info_ptr->row_pointers = NULL;
- }
- info_ptr->valid &= ~PNG_INFO_IDAT;
- }
-#endif
-
- if (num != -1)
- mask &= ~PNG_FREE_MUL;
-
- info_ptr->free_me &= ~mask;
-}
-
-/* This is an internal routine to free any memory that the info struct is
- * pointing to before re-using it or freeing the struct itself. Recall
- * that png_free() checks for NULL pointers for us.
- */
-void /* PRIVATE */
-png_info_destroy(png_structp png_ptr, png_infop info_ptr)
-{
- png_debug(1, "in png_info_destroy");
-
- png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
-
-#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
- if (png_ptr->num_chunk_list)
- {
- png_free(png_ptr, png_ptr->chunk_list);
- png_ptr->chunk_list = NULL;
- png_ptr->num_chunk_list = 0;
- }
-#endif
-
- png_info_init_3(&info_ptr, png_sizeof(png_info));
-}
-#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
-
-/* This function returns a pointer to the io_ptr associated with the user
- * functions. The application should free any memory associated with this
- * pointer before png_write_destroy() or png_read_destroy() are called.
- */
-png_voidp PNGAPI
-png_get_io_ptr(png_structp png_ptr)
-{
- if (png_ptr == NULL)
- return (NULL);
-
- return (png_ptr->io_ptr);
-}
-
-#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
-# ifdef PNG_STDIO_SUPPORTED
-/* Initialize the default input/output functions for the PNG file. If you
- * use your own read or write routines, you can call either png_set_read_fn()
- * or png_set_write_fn() instead of png_init_io(). If you have defined
- * PNG_NO_STDIO or otherwise disabled PNG_STDIO_SUPPORTED, you must use a
- * function of your own because "FILE *" isn't necessarily available.
- */
-void PNGAPI
-png_init_io(png_structp png_ptr, png_FILE_p fp)
-{
- png_debug(1, "in png_init_io");
-
- if (png_ptr == NULL)
- return;
-
- png_ptr->io_ptr = (png_voidp)fp;
-}
-# endif
-
-# ifdef PNG_TIME_RFC1123_SUPPORTED
-/* Convert the supplied time into an RFC 1123 string suitable for use in
- * a "Creation Time" or other text-based time string.
- */
-png_const_charp PNGAPI
-png_convert_to_rfc1123(png_structp png_ptr, png_const_timep ptime)
-{
- static PNG_CONST char short_months[12][4] =
- {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
- "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
-
- if (png_ptr == NULL)
- return (NULL);
-
- if (ptime->year > 9999 /* RFC1123 limitation */ ||
- ptime->month == 0 || ptime->month > 12 ||
- ptime->day == 0 || ptime->day > 31 ||
- ptime->hour > 23 || ptime->minute > 59 ||
- ptime->second > 60)
- {
- png_warning(png_ptr, "Ignoring invalid time value");
- return (NULL);
- }
-
- {
- size_t pos = 0;
- char number_buf[5]; /* enough for a four-digit year */
-
-# define APPEND_STRING(string)\
- pos = png_safecat(png_ptr->time_buffer, sizeof png_ptr->time_buffer,\
- pos, (string))
-# define APPEND_NUMBER(format, value)\
- APPEND_STRING(PNG_FORMAT_NUMBER(number_buf, format, (value)))
-# define APPEND(ch)\
- if (pos < (sizeof png_ptr->time_buffer)-1)\
- png_ptr->time_buffer[pos++] = (ch)
-
- APPEND_NUMBER(PNG_NUMBER_FORMAT_u, (unsigned)ptime->day);
- APPEND(' ');
- APPEND_STRING(short_months[(ptime->month - 1)]);
- APPEND(' ');
- APPEND_NUMBER(PNG_NUMBER_FORMAT_u, ptime->year);
- APPEND(' ');
- APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->hour);
- APPEND(':');
- APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->minute);
- APPEND(':');
- APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->second);
- APPEND_STRING(" +0000"); /* This reliably terminates the buffer */
-
-# undef APPEND
-# undef APPEND_NUMBER
-# undef APPEND_STRING
- }
-
- return png_ptr->time_buffer;
-}
-# endif /* PNG_TIME_RFC1123_SUPPORTED */
-
-#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
-
-png_const_charp PNGAPI
-png_get_copyright(png_const_structp png_ptr)
-{
- PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
-#ifdef PNG_STRING_COPYRIGHT
- return PNG_STRING_COPYRIGHT
-#else
-# ifdef __STDC__
- return PNG_STRING_NEWLINE \
- "libpng version 1.5.9 - February 18, 2012" PNG_STRING_NEWLINE \
- "Copyright (c) 1998-2011 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 1.5.9 - February 18, 2012\
- Copyright (c) 1998-2011 Glenn Randers-Pehrson\
- Copyright (c) 1996-1997 Andreas Dilger\
- Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
-# endif
-#endif
-}
-
-/* The following return the library version as a short string in the
- * format 1.0.0 through 99.99.99zz. To get the version of *.h files
- * used with your application, print out PNG_LIBPNG_VER_STRING, which
- * is defined in png.h.
- * Note: now there is no difference between png_get_libpng_ver() and
- * png_get_header_ver(). Due to the version_nn_nn_nn typedef guard,
- * it is guaranteed that png.c uses the correct version of png.h.
- */
-png_const_charp PNGAPI
-png_get_libpng_ver(png_const_structp png_ptr)
-{
- /* Version of *.c files used when building libpng */
- return png_get_header_ver(png_ptr);
-}
-
-png_const_charp PNGAPI
-png_get_header_ver(png_const_structp png_ptr)
-{
- /* Version of *.h files used when building libpng */
- PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
- return PNG_LIBPNG_VER_STRING;
-}
-
-png_const_charp PNGAPI
-png_get_header_version(png_const_structp png_ptr)
-{
- /* Returns longer string containing both version and date */
- PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
-#ifdef __STDC__
- return PNG_HEADER_VERSION_STRING
-# ifndef PNG_READ_SUPPORTED
- " (NO READ SUPPORT)"
-# endif
- PNG_STRING_NEWLINE;
-#else
- return PNG_HEADER_VERSION_STRING;
-#endif
-}
-
-#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-int PNGAPI
-png_handle_as_unknown(png_structp png_ptr, png_const_bytep chunk_name)
-{
- /* Check chunk_name and return "keep" value if it's on the list, else 0 */
- png_const_bytep p, p_end;
-
- if (png_ptr == NULL || chunk_name == NULL || png_ptr->num_chunk_list <= 0)
- return PNG_HANDLE_CHUNK_AS_DEFAULT;
-
- p_end = png_ptr->chunk_list;
- p = p_end + png_ptr->num_chunk_list*5; /* beyond end */
-
- /* The code is the fifth byte after each four byte string. Historically this
- * code was always searched from the end of the list, so it should continue
- * to do so in case there are duplicated entries.
- */
- do /* num_chunk_list > 0, so at least one */
- {
- p -= 5;
- if (!png_memcmp(chunk_name, p, 4))
- return p[4];
- }
- while (p > p_end);
-
- return PNG_HANDLE_CHUNK_AS_DEFAULT;
-}
-
-int /* PRIVATE */
-png_chunk_unknown_handling(png_structp png_ptr, png_uint_32 chunk_name)
-{
- png_byte chunk_string[5];
-
- PNG_CSTRING_FROM_CHUNK(chunk_string, chunk_name);
- return png_handle_as_unknown(png_ptr, chunk_string);
-}
-#endif
-
-#ifdef PNG_READ_SUPPORTED
-/* This function, added to libpng-1.0.6g, is untested. */
-int PNGAPI
-png_reset_zstream(png_structp png_ptr)
-{
- if (png_ptr == NULL)
- return Z_STREAM_ERROR;
-
- return (inflateReset(&png_ptr->zstream));
-}
-#endif /* PNG_READ_SUPPORTED */
-
-/* This function was added to libpng-1.0.7 */
-png_uint_32 PNGAPI
-png_access_version_number(void)
-{
- /* Version of *.c files used when building libpng */
- return((png_uint_32)PNG_LIBPNG_VER);
-}
-
-
-
-#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
-/* png_convert_size: a PNGAPI but no longer in png.h, so deleted
- * at libpng 1.5.5!
- */
-
-/* Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.c) */
-# ifdef PNG_CHECK_cHRM_SUPPORTED
-
-int /* PRIVATE */
-png_check_cHRM_fixed(png_structp png_ptr,
- png_fixed_point white_x, png_fixed_point white_y, png_fixed_point red_x,
- png_fixed_point red_y, png_fixed_point green_x, png_fixed_point green_y,
- png_fixed_point blue_x, png_fixed_point blue_y)
-{
- int ret = 1;
- unsigned long xy_hi,xy_lo,yx_hi,yx_lo;
-
- png_debug(1, "in function png_check_cHRM_fixed");
-
- if (png_ptr == NULL)
- return 0;
-
- /* (x,y,z) values are first limited to 0..100000 (PNG_FP_1), the white
- * y must also be greater than 0. To test for the upper limit calculate
- * (PNG_FP_1-y) - x must be <= to this for z to be >= 0 (and the expression
- * cannot overflow.) At this point we know x and y are >= 0 and (x+y) is
- * <= PNG_FP_1. The previous test on PNG_MAX_UINT_31 is removed because it
- * pointless (and it produces compiler warnings!)
- */
- if (white_x < 0 || white_y <= 0 ||
- red_x < 0 || red_y < 0 ||
- green_x < 0 || green_y < 0 ||
- blue_x < 0 || blue_y < 0)
- {
- png_warning(png_ptr,
- "Ignoring attempt to set negative chromaticity value");
- ret = 0;
- }
- /* And (x+y) must be <= PNG_FP_1 (so z is >= 0) */
- if (white_x > PNG_FP_1 - white_y)
- {
- png_warning(png_ptr, "Invalid cHRM white point");
- ret = 0;
- }
-
- if (red_x > PNG_FP_1 - red_y)
- {
- png_warning(png_ptr, "Invalid cHRM red point");
- ret = 0;
- }
-
- if (green_x > PNG_FP_1 - green_y)
- {
- png_warning(png_ptr, "Invalid cHRM green point");
- ret = 0;
- }
-
- if (blue_x > PNG_FP_1 - blue_y)
- {
- png_warning(png_ptr, "Invalid cHRM blue point");
- ret = 0;
- }
-
- png_64bit_product(green_x - red_x, blue_y - red_y, &xy_hi, &xy_lo);
- png_64bit_product(green_y - red_y, blue_x - red_x, &yx_hi, &yx_lo);
-
- if (xy_hi == yx_hi && xy_lo == yx_lo)
- {
- png_warning(png_ptr,
- "Ignoring attempt to set cHRM RGB triangle with zero area");
- ret = 0;
- }
-
- return ret;
-}
-# endif /* PNG_CHECK_cHRM_SUPPORTED */
-
-#ifdef PNG_cHRM_SUPPORTED
-/* Added at libpng-1.5.5 to support read and write of true CIEXYZ values for
- * cHRM, as opposed to using chromaticities. These internal APIs return
- * non-zero on a parameter error. The X, Y and Z values are required to be
- * positive and less than 1.0.
- */
-int png_xy_from_XYZ(png_xy *xy, png_XYZ XYZ)
-{
- png_int_32 d, dwhite, whiteX, whiteY;
-
- d = XYZ.redX + XYZ.redY + XYZ.redZ;
- if (!png_muldiv(&xy->redx, XYZ.redX, PNG_FP_1, d)) return 1;
- if (!png_muldiv(&xy->redy, XYZ.redY, PNG_FP_1, d)) return 1;
- dwhite = d;
- whiteX = XYZ.redX;
- whiteY = XYZ.redY;
-
- d = XYZ.greenX + XYZ.greenY + XYZ.greenZ;
- if (!png_muldiv(&xy->greenx, XYZ.greenX, PNG_FP_1, d)) return 1;
- if (!png_muldiv(&xy->greeny, XYZ.greenY, PNG_FP_1, d)) return 1;
- dwhite += d;
- whiteX += XYZ.greenX;
- whiteY += XYZ.greenY;
-
- d = XYZ.blueX + XYZ.blueY + XYZ.blueZ;
- if (!png_muldiv(&xy->bluex, XYZ.blueX, PNG_FP_1, d)) return 1;
- if (!png_muldiv(&xy->bluey, XYZ.blueY, PNG_FP_1, d)) return 1;
- dwhite += d;
- whiteX += XYZ.blueX;
- whiteY += XYZ.blueY;
-
- /* The reference white is simply the same of the end-point (X,Y,Z) vectors,
- * thus:
- */
- if (!png_muldiv(&xy->whitex, whiteX, PNG_FP_1, dwhite)) return 1;
- if (!png_muldiv(&xy->whitey, whiteY, PNG_FP_1, dwhite)) return 1;
-
- return 0;
-}
-
-int png_XYZ_from_xy(png_XYZ *XYZ, png_xy xy)
-{
- png_fixed_point red_inverse, green_inverse, blue_scale;
- png_fixed_point left, right, denominator;
-
- /* Check xy and, implicitly, z. Note that wide gamut color spaces typically
- * have end points with 0 tristimulus values (these are impossible end
- * points, but they are used to cover the possible colors.)
- */
- if (xy.redx < 0 || xy.redx > PNG_FP_1) return 1;
- if (xy.redy < 0 || xy.redy > PNG_FP_1-xy.redx) return 1;
- if (xy.greenx < 0 || xy.greenx > PNG_FP_1) return 1;
- if (xy.greeny < 0 || xy.greeny > PNG_FP_1-xy.greenx) return 1;
- if (xy.bluex < 0 || xy.bluex > PNG_FP_1) return 1;
- if (xy.bluey < 0 || xy.bluey > PNG_FP_1-xy.bluex) return 1;
- if (xy.whitex < 0 || xy.whitex > PNG_FP_1) return 1;
- if (xy.whitey < 0 || xy.whitey > PNG_FP_1-xy.whitex) return 1;
-
- /* The reverse calculation is more difficult because the original tristimulus
- * value had 9 independent values (red,green,blue)x(X,Y,Z) however only 8
- * derived values were recorded in the cHRM chunk;
- * (red,green,blue,white)x(x,y). This loses one degree of freedom and
- * therefore an arbitrary ninth value has to be introduced to undo the
- * original transformations.
- *
- * Think of the original end-points as points in (X,Y,Z) space. The
- * chromaticity values (c) have the property:
- *
- * C
- * c = ---------
- * X + Y + Z
- *
- * For each c (x,y,z) from the corresponding original C (X,Y,Z). Thus the
- * three chromaticity values (x,y,z) for each end-point obey the
- * relationship:
- *
- * x + y + z = 1
- *
- * This describes the plane in (X,Y,Z) space that intersects each axis at the
- * value 1.0; call this the chromaticity plane. Thus the chromaticity
- * calculation has scaled each end-point so that it is on the x+y+z=1 plane
- * and chromaticity is the intersection of the vector from the origin to the
- * (X,Y,Z) value with the chromaticity plane.
- *
- * To fully invert the chromaticity calculation we would need the three
- * end-point scale factors, (red-scale, green-scale, blue-scale), but these
- * were not recorded. Instead we calculated the reference white (X,Y,Z) and
- * recorded the chromaticity of this. The reference white (X,Y,Z) would have
- * given all three of the scale factors since:
- *
- * color-C = color-c * color-scale
- * white-C = red-C + green-C + blue-C
- * = red-c*red-scale + green-c*green-scale + blue-c*blue-scale
- *
- * But cHRM records only white-x and white-y, so we have lost the white scale
- * factor:
- *
- * white-C = white-c*white-scale
- *
- * To handle this the inverse transformation makes an arbitrary assumption
- * about white-scale:
- *
- * Assume: white-Y = 1.0
- * Hence: white-scale = 1/white-y
- * Or: red-Y + green-Y + blue-Y = 1.0
- *
- * Notice the last statement of the assumption gives an equation in three of
- * the nine values we want to calculate. 8 more equations come from the
- * above routine as summarised at the top above (the chromaticity
- * calculation):
- *
- * Given: color-x = color-X / (color-X + color-Y + color-Z)
- * Hence: (color-x - 1)*color-X + color.x*color-Y + color.x*color-Z = 0
- *
- * This is 9 simultaneous equations in the 9 variables "color-C" and can be
- * solved by Cramer's rule. Cramer's rule requires calculating 10 9x9 matrix
- * determinants, however this is not as bad as it seems because only 28 of
- * the total of 90 terms in the various matrices are non-zero. Nevertheless
- * Cramer's rule is notoriously numerically unstable because the determinant
- * calculation involves the difference of large, but similar, numbers. It is
- * difficult to be sure that the calculation is stable for real world values
- * and it is certain that it becomes unstable where the end points are close
- * together.
- *
- * So this code uses the perhaps slighly less optimal but more understandable
- * and totally obvious approach of calculating color-scale.
- *
- * This algorithm depends on the precision in white-scale and that is
- * (1/white-y), so we can immediately see that as white-y approaches 0 the
- * accuracy inherent in the cHRM chunk drops off substantially.
- *
- * libpng arithmetic: a simple invertion of the above equations
- * ------------------------------------------------------------
- *
- * white_scale = 1/white-y
- * white-X = white-x * white-scale
- * white-Y = 1.0
- * white-Z = (1 - white-x - white-y) * white_scale
- *
- * white-C = red-C + green-C + blue-C
- * = red-c*red-scale + green-c*green-scale + blue-c*blue-scale
- *
- * This gives us three equations in (red-scale,green-scale,blue-scale) where
- * all the coefficients are now known:
- *
- * red-x*red-scale + green-x*green-scale + blue-x*blue-scale
- * = white-x/white-y
- * red-y*red-scale + green-y*green-scale + blue-y*blue-scale = 1
- * red-z*red-scale + green-z*green-scale + blue-z*blue-scale
- * = (1 - white-x - white-y)/white-y
- *
- * In the last equation color-z is (1 - color-x - color-y) so we can add all
- * three equations together to get an alternative third:
- *
- * red-scale + green-scale + blue-scale = 1/white-y = white-scale
- *
- * So now we have a Cramer's rule solution where the determinants are just
- * 3x3 - far more tractible. Unfortunately 3x3 determinants still involve
- * multiplication of three coefficients so we can't guarantee to avoid
- * overflow in the libpng fixed point representation. Using Cramer's rule in
- * floating point is probably a good choice here, but it's not an option for
- * fixed point. Instead proceed to simplify the first two equations by
- * eliminating what is likely to be the largest value, blue-scale:
- *
- * blue-scale = white-scale - red-scale - green-scale
- *
- * Hence:
- *
- * (red-x - blue-x)*red-scale + (green-x - blue-x)*green-scale =
- * (white-x - blue-x)*white-scale
- *
- * (red-y - blue-y)*red-scale + (green-y - blue-y)*green-scale =
- * 1 - blue-y*white-scale
- *
- * And now we can trivially solve for (red-scale,green-scale):
- *
- * green-scale =
- * (white-x - blue-x)*white-scale - (red-x - blue-x)*red-scale
- * -----------------------------------------------------------
- * green-x - blue-x
- *
- * red-scale =
- * 1 - blue-y*white-scale - (green-y - blue-y) * green-scale
- * ---------------------------------------------------------
- * red-y - blue-y
- *
- * Hence:
- *
- * red-scale =
- * ( (green-x - blue-x) * (white-y - blue-y) -
- * (green-y - blue-y) * (white-x - blue-x)) / white-y
- * -------------------------------------------------------------------------
- * (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x)
- *
- * green-scale =
- * ( (red-y - blue-y) * (white-x - blue-x) -
- * (red-x - blue-x) * (white-y - blue-y)) / white-y
- * -------------------------------------------------------------------------
- * (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x)
- *
- * Accuracy:
- * The input values have 5 decimal digits of accuracy. The values are all in
- * the range 0 < value < 1, so simple products are in the same range but may
- * need up to 10 decimal digits to preserve the original precision and avoid
- * underflow. Because we are using a 32-bit signed representation we cannot
- * match this; the best is a little over 9 decimal digits, less than 10.
- *
- * The approach used here is to preserve the maximum precision within the
- * signed representation. Because the red-scale calculation above uses the
- * difference between two products of values that must be in the range -1..+1
- * it is sufficient to divide the product by 7; ceil(100,000/32767*2). The
- * factor is irrelevant in the calculation because it is applied to both
- * numerator and denominator.
- *
- * Note that the values of the differences of the products of the
- * chromaticities in the above equations tend to be small, for example for
- * the sRGB chromaticities they are:
- *
- * red numerator: -0.04751
- * green numerator: -0.08788
- * denominator: -0.2241 (without white-y multiplication)
- *
- * The resultant Y coefficients from the chromaticities of some widely used
- * color space definitions are (to 15 decimal places):
- *
- * sRGB
- * 0.212639005871510 0.715168678767756 0.072192315360734
- * Kodak ProPhoto
- * 0.288071128229293 0.711843217810102 0.000085653960605
- * Adobe RGB
- * 0.297344975250536 0.627363566255466 0.075291458493998
- * Adobe Wide Gamut RGB
- * 0.258728243040113 0.724682314948566 0.016589442011321
- */
- /* By the argument, above overflow should be impossible here. The return
- * value of 2 indicates an internal error to the caller.
- */
- if (!png_muldiv(&left, xy.greenx-xy.bluex, xy.redy - xy.bluey, 7)) return 2;
- if (!png_muldiv(&right, xy.greeny-xy.bluey, xy.redx - xy.bluex, 7)) return 2;
- denominator = left - right;
-
- /* Now find the red numerator. */
- if (!png_muldiv(&left, xy.greenx-xy.bluex, xy.whitey-xy.bluey, 7)) return 2;
- if (!png_muldiv(&right, xy.greeny-xy.bluey, xy.whitex-xy.bluex, 7)) return 2;
-
- /* Overflow is possible here and it indicates an extreme set of PNG cHRM
- * chunk values. This calculation actually returns the reciprocal of the
- * scale value because this allows us to delay the multiplication of white-y
- * into the denominator, which tends to produce a small number.
- */
- if (!png_muldiv(&red_inverse, xy.whitey, denominator, left-right) ||
- red_inverse <= xy.whitey /* r+g+b scales = white scale */)
- return 1;
-
- /* Similarly for green_inverse: */
- if (!png_muldiv(&left, xy.redy-xy.bluey, xy.whitex-xy.bluex, 7)) return 2;
- if (!png_muldiv(&right, xy.redx-xy.bluex, xy.whitey-xy.bluey, 7)) return 2;
- if (!png_muldiv(&green_inverse, xy.whitey, denominator, left-right) ||
- green_inverse <= xy.whitey)
- return 1;
-
- /* And the blue scale, the checks above guarantee this can't overflow but it
- * can still produce 0 for extreme cHRM values.
- */
- blue_scale = png_reciprocal(xy.whitey) - png_reciprocal(red_inverse) -
- png_reciprocal(green_inverse);
- if (blue_scale <= 0) return 1;
-
-
- /* And fill in the png_XYZ: */
- if (!png_muldiv(&XYZ->redX, xy.redx, PNG_FP_1, red_inverse)) return 1;
- if (!png_muldiv(&XYZ->redY, xy.redy, PNG_FP_1, red_inverse)) return 1;
- if (!png_muldiv(&XYZ->redZ, PNG_FP_1 - xy.redx - xy.redy, PNG_FP_1,
- red_inverse))
- return 1;
-
- if (!png_muldiv(&XYZ->greenX, xy.greenx, PNG_FP_1, green_inverse)) return 1;
- if (!png_muldiv(&XYZ->greenY, xy.greeny, PNG_FP_1, green_inverse)) return 1;
- if (!png_muldiv(&XYZ->greenZ, PNG_FP_1 - xy.greenx - xy.greeny, PNG_FP_1,
- green_inverse))
- return 1;
-
- if (!png_muldiv(&XYZ->blueX, xy.bluex, blue_scale, PNG_FP_1)) return 1;
- if (!png_muldiv(&XYZ->blueY, xy.bluey, blue_scale, PNG_FP_1)) return 1;
- if (!png_muldiv(&XYZ->blueZ, PNG_FP_1 - xy.bluex - xy.bluey, blue_scale,
- PNG_FP_1))
- return 1;
-
- return 0; /*success*/
-}
-
-int png_XYZ_from_xy_checked(png_structp png_ptr, png_XYZ *XYZ, png_xy xy)
-{
- switch (png_XYZ_from_xy(XYZ, xy))
- {
- case 0: /* success */
- return 1;
-
- case 1:
- /* The chunk may be technically valid, but we got png_fixed_point
- * overflow while trying to get XYZ values out of it. This is
- * entirely benign - the cHRM chunk is pretty extreme.
- */
- png_warning(png_ptr,
- "extreme cHRM chunk cannot be converted to tristimulus values");
- break;
-
- default:
- /* libpng is broken; this should be a warning but if it happens we
- * want error reports so for the moment it is an error.
- */
- png_error(png_ptr, "internal error in png_XYZ_from_xy");
- break;
- }
-
- /* ERROR RETURN */
- return 0;
-}
-#endif
-
-void /* PRIVATE */
-png_check_IHDR(png_structp png_ptr,
- png_uint_32 width, png_uint_32 height, int bit_depth,
- int color_type, int interlace_type, int compression_type,
- int filter_type)
-{
- int error = 0;
-
- /* Check for width and height valid values */
- if (width == 0)
- {
- png_warning(png_ptr, "Image width is zero in IHDR");
- error = 1;
- }
-
- if (height == 0)
- {
- png_warning(png_ptr, "Image height is zero in IHDR");
- error = 1;
- }
-
-# ifdef PNG_SET_USER_LIMITS_SUPPORTED
- if (width > png_ptr->user_width_max)
-
-# else
- if (width > PNG_USER_WIDTH_MAX)
-# endif
- {
- png_warning(png_ptr, "Image width exceeds user limit in IHDR");
- error = 1;
- }
-
-# ifdef PNG_SET_USER_LIMITS_SUPPORTED
- if (height > png_ptr->user_height_max)
-# else
- if (height > PNG_USER_HEIGHT_MAX)
-# endif
- {
- png_warning(png_ptr, "Image height exceeds user limit in IHDR");
- error = 1;
- }
-
- if (width > PNG_UINT_31_MAX)
- {
- png_warning(png_ptr, "Invalid image width in IHDR");
- error = 1;
- }
-
- if (height > PNG_UINT_31_MAX)
- {
- png_warning(png_ptr, "Invalid image height in IHDR");
- error = 1;
- }
-
- if (width > (PNG_UINT_32_MAX
- >> 3) /* 8-byte RGBA pixels */
- - 48 /* bigrowbuf hack */
- - 1 /* filter byte */
- - 7*8 /* rounding of width to multiple of 8 pixels */
- - 8) /* extra max_pixel_depth pad */
- png_warning(png_ptr, "Width is too large for libpng to process pixels");
-
- /* Check other values */
- if (bit_depth != 1 && bit_depth != 2 && bit_depth != 4 &&
- bit_depth != 8 && bit_depth != 16)
- {
- png_warning(png_ptr, "Invalid bit depth in IHDR");
- error = 1;
- }
-
- if (color_type < 0 || color_type == 1 ||
- color_type == 5 || color_type > 6)
- {
- png_warning(png_ptr, "Invalid color type in IHDR");
- error = 1;
- }
-
- if (((color_type == PNG_COLOR_TYPE_PALETTE) && bit_depth > 8) ||
- ((color_type == PNG_COLOR_TYPE_RGB ||
- color_type == PNG_COLOR_TYPE_GRAY_ALPHA ||
- color_type == PNG_COLOR_TYPE_RGB_ALPHA) && bit_depth < 8))
- {
- png_warning(png_ptr, "Invalid color type/bit depth combination in IHDR");
- error = 1;
- }
-
- if (interlace_type >= PNG_INTERLACE_LAST)
- {
- png_warning(png_ptr, "Unknown interlace method in IHDR");
- error = 1;
- }
-
- if (compression_type != PNG_COMPRESSION_TYPE_BASE)
- {
- png_warning(png_ptr, "Unknown compression method in IHDR");
- error = 1;
- }
-
-# ifdef PNG_MNG_FEATURES_SUPPORTED
- /* Accept filter_method 64 (intrapixel differencing) only if
- * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
- * 2. Libpng did not read a PNG signature (this filter_method is only
- * used in PNG datastreams that are embedded in MNG datastreams) and
- * 3. The application called png_permit_mng_features with a mask that
- * included PNG_FLAG_MNG_FILTER_64 and
- * 4. The filter_method is 64 and
- * 5. The color_type is RGB or RGBA
- */
- if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) &&
- png_ptr->mng_features_permitted)
- png_warning(png_ptr, "MNG features are not allowed in a PNG datastream");
-
- if (filter_type != PNG_FILTER_TYPE_BASE)
- {
- if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
- (filter_type == PNG_INTRAPIXEL_DIFFERENCING) &&
- ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
- (color_type == PNG_COLOR_TYPE_RGB ||
- color_type == PNG_COLOR_TYPE_RGB_ALPHA)))
- {
- png_warning(png_ptr, "Unknown filter method in IHDR");
- error = 1;
- }
-
- if (png_ptr->mode & PNG_HAVE_PNG_SIGNATURE)
- {
- png_warning(png_ptr, "Invalid filter method in IHDR");
- error = 1;
- }
- }
-
-# else
- if (filter_type != PNG_FILTER_TYPE_BASE)
- {
- png_warning(png_ptr, "Unknown filter method in IHDR");
- error = 1;
- }
-# endif
-
- if (error == 1)
- png_error(png_ptr, "Invalid IHDR data");
-}
-
-#if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED)
-/* ASCII to fp functions */
-/* Check an ASCII formated floating point value, see the more detailed
- * comments in pngpriv.h
- */
-/* The following is used internally to preserve the sticky flags */
-#define png_fp_add(state, flags) ((state) |= (flags))
-#define png_fp_set(state, value) ((state) = (value) | ((state) & PNG_FP_STICKY))
-
-int /* PRIVATE */
-png_check_fp_number(png_const_charp string, png_size_t size, int *statep,
- png_size_tp whereami)
-{
- int state = *statep;
- png_size_t i = *whereami;
-
- while (i < size)
- {
- int type;
- /* First find the type of the next character */
- switch (string[i])
- {
- case 43: type = PNG_FP_SAW_SIGN; break;
- case 45: type = PNG_FP_SAW_SIGN + PNG_FP_NEGATIVE; break;
- case 46: type = PNG_FP_SAW_DOT; break;
- case 48: type = PNG_FP_SAW_DIGIT; break;
- case 49: case 50: case 51: case 52:
- case 53: case 54: case 55: case 56:
- case 57: type = PNG_FP_SAW_DIGIT + PNG_FP_NONZERO; break;
- case 69:
- case 101: type = PNG_FP_SAW_E; break;
- default: goto PNG_FP_End;
- }
-
- /* Now deal with this type according to the current
- * state, the type is arranged to not overlap the
- * bits of the PNG_FP_STATE.
- */
- switch ((state & PNG_FP_STATE) + (type & PNG_FP_SAW_ANY))
- {
- case PNG_FP_INTEGER + PNG_FP_SAW_SIGN:
- if (state & PNG_FP_SAW_ANY)
- goto PNG_FP_End; /* not a part of the number */
-
- png_fp_add(state, type);
- break;
-
- case PNG_FP_INTEGER + PNG_FP_SAW_DOT:
- /* Ok as trailer, ok as lead of fraction. */
- if (state & PNG_FP_SAW_DOT) /* two dots */
- goto PNG_FP_End;
-
- else if (state & PNG_FP_SAW_DIGIT) /* trailing dot? */
- png_fp_add(state, type);
-
- else
- png_fp_set(state, PNG_FP_FRACTION | type);
-
- break;
-
- case PNG_FP_INTEGER + PNG_FP_SAW_DIGIT:
- if (state & PNG_FP_SAW_DOT) /* delayed fraction */
- png_fp_set(state, PNG_FP_FRACTION | PNG_FP_SAW_DOT);
-
- png_fp_add(state, type | PNG_FP_WAS_VALID);
-
- break;
-
- case PNG_FP_INTEGER + PNG_FP_SAW_E:
- if ((state & PNG_FP_SAW_DIGIT) == 0)
- goto PNG_FP_End;
-
- png_fp_set(state, PNG_FP_EXPONENT);
-
- break;
-
- /* case PNG_FP_FRACTION + PNG_FP_SAW_SIGN:
- goto PNG_FP_End; ** no sign in fraction */
-
- /* case PNG_FP_FRACTION + PNG_FP_SAW_DOT:
- goto PNG_FP_End; ** Because SAW_DOT is always set */
-
- case PNG_FP_FRACTION + PNG_FP_SAW_DIGIT:
- png_fp_add(state, type | PNG_FP_WAS_VALID);
- break;
-
- case PNG_FP_FRACTION + PNG_FP_SAW_E:
- /* This is correct because the trailing '.' on an
- * integer is handled above - so we can only get here
- * with the sequence ".E" (with no preceding digits).
- */
- if ((state & PNG_FP_SAW_DIGIT) == 0)
- goto PNG_FP_End;
-
- png_fp_set(state, PNG_FP_EXPONENT);
-
- break;
-
- case PNG_FP_EXPONENT + PNG_FP_SAW_SIGN:
- if (state & PNG_FP_SAW_ANY)
- goto PNG_FP_End; /* not a part of the number */
-
- png_fp_add(state, PNG_FP_SAW_SIGN);
-
- break;
-
- /* case PNG_FP_EXPONENT + PNG_FP_SAW_DOT:
- goto PNG_FP_End; */
-
- case PNG_FP_EXPONENT + PNG_FP_SAW_DIGIT:
- png_fp_add(state, PNG_FP_SAW_DIGIT | PNG_FP_WAS_VALID);
-
- break;
-
- /* case PNG_FP_EXPONEXT + PNG_FP_SAW_E:
- goto PNG_FP_End; */
-
- default: goto PNG_FP_End; /* I.e. break 2 */
- }
-
- /* The character seems ok, continue. */
- ++i;
- }
-
-PNG_FP_End:
- /* Here at the end, update the state and return the correct
- * return code.
- */
- *statep = state;
- *whereami = i;
-
- return (state & PNG_FP_SAW_DIGIT) != 0;
-}
-
-
-/* The same but for a complete string. */
-int
-png_check_fp_string(png_const_charp string, png_size_t size)
-{
- int state=0;
- png_size_t char_index=0;
-
- if (png_check_fp_number(string, size, &state, &char_index) &&
- (char_index == size || string[char_index] == 0))
- return state /* must be non-zero - see above */;
-
- return 0; /* i.e. fail */
-}
-#endif /* pCAL or sCAL */
-
-#ifdef PNG_READ_sCAL_SUPPORTED
-# ifdef PNG_FLOATING_POINT_SUPPORTED
-/* Utility used below - a simple accurate power of ten from an integral
- * exponent.
- */
-static double
-png_pow10(int power)
-{
- int recip = 0;
- double d = 1;
-
- /* Handle negative exponent with a reciprocal at the end because
- * 10 is exact whereas .1 is inexact in base 2
- */
- if (power < 0)
- {
- if (power < DBL_MIN_10_EXP) return 0;
- recip = 1, power = -power;
- }
-
- if (power > 0)
- {
- /* Decompose power bitwise. */
- double mult = 10;
- do
- {
- if (power & 1) d *= mult;
- mult *= mult;
- power >>= 1;
- }
- while (power > 0);
-
- if (recip) d = 1/d;
- }
- /* else power is 0 and d is 1 */
-
- return d;
-}
-
-/* Function to format a floating point value in ASCII with a given
- * precision.
- */
-void /* PRIVATE */
-png_ascii_from_fp(png_structp png_ptr, png_charp ascii, png_size_t size,
- double fp, unsigned int precision)
-{
- /* We use standard functions from math.h, but not printf because
- * that would require stdio. The caller must supply a buffer of
- * sufficient size or we will png_error. The tests on size and
- * the space in ascii[] consumed are indicated below.
- */
- if (precision < 1)
- precision = DBL_DIG;
-
- /* Enforce the limit of the implementation precision too. */
- if (precision > DBL_DIG+1)
- precision = DBL_DIG+1;
-
- /* Basic sanity checks */
- if (size >= precision+5) /* See the requirements below. */
- {
- if (fp < 0)
- {
- fp = -fp;
- *ascii++ = 45; /* '-' PLUS 1 TOTAL 1 */
- --size;
- }
-
- if (fp >= DBL_MIN && fp <= DBL_MAX)
- {
- int exp_b10; /* A base 10 exponent */
- double base; /* 10^exp_b10 */
-
- /* First extract a base 10 exponent of the number,
- * the calculation below rounds down when converting
- * from base 2 to base 10 (multiply by log10(2) -
- * 0.3010, but 77/256 is 0.3008, so exp_b10 needs to
- * be increased. Note that the arithmetic shift
- * performs a floor() unlike C arithmetic - using a
- * C multiply would break the following for negative
- * exponents.
- */
- (void)frexp(fp, &exp_b10); /* exponent to base 2 */
-
- exp_b10 = (exp_b10 * 77) >> 8; /* <= exponent to base 10 */
-
- /* Avoid underflow here. */
- base = png_pow10(exp_b10); /* May underflow */
-
- while (base < DBL_MIN || base < fp)
- {
- /* And this may overflow. */
- double test = png_pow10(exp_b10+1);
-
- if (test <= DBL_MAX)
- ++exp_b10, base = test;
-
- else
- break;
- }
-
- /* Normalize fp and correct exp_b10, after this fp is in the
- * range [.1,1) and exp_b10 is both the exponent and the digit
- * *before* which the decimal point should be inserted
- * (starting with 0 for the first digit). Note that this
- * works even if 10^exp_b10 is out of range because of the
- * test on DBL_MAX above.
- */
- fp /= base;
- while (fp >= 1) fp /= 10, ++exp_b10;
-
- /* Because of the code above fp may, at this point, be
- * less than .1, this is ok because the code below can
- * handle the leading zeros this generates, so no attempt
- * is made to correct that here.
- */
-
- {
- int czero, clead, cdigits;
- char exponent[10];
-
- /* Allow up to two leading zeros - this will not lengthen
- * the number compared to using E-n.
- */
- if (exp_b10 < 0 && exp_b10 > -3) /* PLUS 3 TOTAL 4 */
- {
- czero = -exp_b10; /* PLUS 2 digits: TOTAL 3 */
- exp_b10 = 0; /* Dot added below before first output. */
- }
- else
- czero = 0; /* No zeros to add */
-
- /* Generate the digit list, stripping trailing zeros and
- * inserting a '.' before a digit if the exponent is 0.
- */
- clead = czero; /* Count of leading zeros */
- cdigits = 0; /* Count of digits in list. */
-
- do
- {
- double d;
-
- fp *= 10;
- /* Use modf here, not floor and subtract, so that
- * the separation is done in one step. At the end
- * of the loop don't break the number into parts so
- * that the final digit is rounded.
- */
- if (cdigits+czero-clead+1 < (int)precision)
- fp = modf(fp, &d);
-
- else
- {
- d = floor(fp + .5);
-
- if (d > 9)
- {
- /* Rounding up to 10, handle that here. */
- if (czero > 0)
- {
- --czero, d = 1;
- if (cdigits == 0) --clead;
- }
- else
- {
- while (cdigits > 0 && d > 9)
- {
- int ch = *--ascii;
-
- if (exp_b10 != (-1))
- ++exp_b10;
-
- else if (ch == 46)
- {
- ch = *--ascii, ++size;
- /* Advance exp_b10 to '1', so that the
- * decimal point happens after the
- * previous digit.
- */
- exp_b10 = 1;
- }
-
- --cdigits;
- d = ch - 47; /* I.e. 1+(ch-48) */
- }
-
- /* Did we reach the beginning? If so adjust the
- * exponent but take into account the leading
- * decimal point.
- */
- if (d > 9) /* cdigits == 0 */
- {
- if (exp_b10 == (-1))
- {
- /* Leading decimal point (plus zeros?), if
- * we lose the decimal point here it must
- * be reentered below.
- */
- int ch = *--ascii;
-
- if (ch == 46)
- ++size, exp_b10 = 1;
-
- /* Else lost a leading zero, so 'exp_b10' is
- * still ok at (-1)
- */
- }
- else
- ++exp_b10;
-
- /* In all cases we output a '1' */
- d = 1;
- }
- }
- }
- fp = 0; /* Guarantees termination below. */
- }
-
- if (d == 0)
- {
- ++czero;
- if (cdigits == 0) ++clead;
- }
- else
- {
- /* Included embedded zeros in the digit count. */
- cdigits += czero - clead;
- clead = 0;
-
- while (czero > 0)
- {
- /* exp_b10 == (-1) means we just output the decimal
- * place - after the DP don't adjust 'exp_b10' any
- * more!
- */
- if (exp_b10 != (-1))
- {
- if (exp_b10 == 0) *ascii++ = 46, --size;
- /* PLUS 1: TOTAL 4 */
- --exp_b10;
- }
- *ascii++ = 48, --czero;
- }
-
- if (exp_b10 != (-1))
- {
- if (exp_b10 == 0) *ascii++ = 46, --size; /* counted
- above */
- --exp_b10;
- }
- *ascii++ = (char)(48 + (int)d), ++cdigits;
- }
- }
- while (cdigits+czero-clead < (int)precision && fp > DBL_MIN);
-
- /* The total output count (max) is now 4+precision */
-
- /* Check for an exponent, if we don't need one we are
- * done and just need to terminate the string. At
- * this point exp_b10==(-1) is effectively if flag - it got
- * to '-1' because of the decrement after outputing
- * the decimal point above (the exponent required is
- * *not* -1!)
- */
- if (exp_b10 >= (-1) && exp_b10 <= 2)
- {
- /* The following only happens if we didn't output the
- * leading zeros above for negative exponent, so this
- * doest add to the digit requirement. Note that the
- * two zeros here can only be output if the two leading
- * zeros were *not* output, so this doesn't increase
- * the output count.
- */
- while (--exp_b10 >= 0) *ascii++ = 48;
-
- *ascii = 0;
-
- /* Total buffer requirement (including the '\0') is
- * 5+precision - see check at the start.
- */
- return;
- }
-
- /* Here if an exponent is required, adjust size for
- * the digits we output but did not count. The total
- * digit output here so far is at most 1+precision - no
- * decimal point and no leading or trailing zeros have
- * been output.
- */
- size -= cdigits;
-
- *ascii++ = 69, --size; /* 'E': PLUS 1 TOTAL 2+precision */
-
- /* The following use of an unsigned temporary avoids ambiguities in
- * the signed arithmetic on exp_b10 and permits GCC at least to do
- * better optimization.
- */
- {
- unsigned int uexp_b10;
-
- if (exp_b10 < 0)
- {
- *ascii++ = 45, --size; /* '-': PLUS 1 TOTAL 3+precision */
- uexp_b10 = -exp_b10;
- }
-
- else
- uexp_b10 = exp_b10;
-
- cdigits = 0;
-
- while (uexp_b10 > 0)
- {
- exponent[cdigits++] = (char)(48 + uexp_b10 % 10);
- uexp_b10 /= 10;
- }
- }
-
- /* Need another size check here for the exponent digits, so
- * this need not be considered above.
- */
- if ((int)size > cdigits)
- {
- while (cdigits > 0) *ascii++ = exponent[--cdigits];
-
- *ascii = 0;
-
- return;
- }
- }
- }
- else if (!(fp >= DBL_MIN))
- {
- *ascii++ = 48; /* '0' */
- *ascii = 0;
- return;
- }
- else
- {
- *ascii++ = 105; /* 'i' */
- *ascii++ = 110; /* 'n' */
- *ascii++ = 102; /* 'f' */
- *ascii = 0;
- return;
- }
- }
-
- /* Here on buffer too small. */
- png_error(png_ptr, "ASCII conversion buffer too small");
-}
-
-# endif /* FLOATING_POINT */
-
-# ifdef PNG_FIXED_POINT_SUPPORTED
-/* Function to format a fixed point value in ASCII.
- */
-void /* PRIVATE */
-png_ascii_from_fixed(png_structp png_ptr, png_charp ascii, png_size_t size,
- png_fixed_point fp)
-{
- /* Require space for 10 decimal digits, a decimal point, a minus sign and a
- * trailing \0, 13 characters:
- */
- if (size > 12)
- {
- png_uint_32 num;
-
- /* Avoid overflow here on the minimum integer. */
- if (fp < 0)
- *ascii++ = 45, --size, num = -fp;
- else
- num = fp;
-
- if (num <= 0x80000000) /* else overflowed */
- {
- unsigned int ndigits = 0, first = 16 /* flag value */;
- char digits[10];
-
- while (num)
- {
- /* Split the low digit off num: */
- unsigned int tmp = num/10;
- num -= tmp*10;
- digits[ndigits++] = (char)(48 + num);
- /* Record the first non-zero digit, note that this is a number
- * starting at 1, it's not actually the array index.
- */
- if (first == 16 && num > 0)
- first = ndigits;
- num = tmp;
- }
-
- if (ndigits > 0)
- {
- while (ndigits > 5) *ascii++ = digits[--ndigits];
- /* The remaining digits are fractional digits, ndigits is '5' or
- * smaller at this point. It is certainly not zero. Check for a
- * non-zero fractional digit:
- */
- if (first <= 5)
- {
- unsigned int i;
- *ascii++ = 46; /* decimal point */
- /* ndigits may be <5 for small numbers, output leading zeros
- * then ndigits digits to first:
- */
- i = 5;
- while (ndigits < i) *ascii++ = 48, --i;
- while (ndigits >= first) *ascii++ = digits[--ndigits];
- /* Don't output the trailing zeros! */
- }
- }
- else
- *ascii++ = 48;
-
- /* And null terminate the string: */
- *ascii = 0;
- return;
- }
- }
-
- /* Here on buffer too small. */
- png_error(png_ptr, "ASCII conversion buffer too small");
-}
-# endif /* FIXED_POINT */
-#endif /* READ_SCAL */
-
-#if defined(PNG_FLOATING_POINT_SUPPORTED) && \
- !defined(PNG_FIXED_POINT_MACRO_SUPPORTED)
-png_fixed_point
-png_fixed(png_structp png_ptr, double fp, png_const_charp text)
-{
- double r = floor(100000 * fp + .5);
-
- if (r > 2147483647. || r < -2147483648.)
- png_fixed_error(png_ptr, text);
-
- return (png_fixed_point)r;
-}
-#endif
-
-#if defined(PNG_READ_GAMMA_SUPPORTED) || \
- defined(PNG_INCH_CONVERSIONS_SUPPORTED) || defined(PNG__READ_pHYs_SUPPORTED)
-/* muldiv functions */
-/* This API takes signed arguments and rounds the result to the nearest
- * integer (or, for a fixed point number - the standard argument - to
- * the nearest .00001). Overflow and divide by zero are signalled in
- * the result, a boolean - true on success, false on overflow.
- */
-int
-png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times,
- png_int_32 divisor)
-{
- /* Return a * times / divisor, rounded. */
- if (divisor != 0)
- {
- if (a == 0 || times == 0)
- {
- *res = 0;
- return 1;
- }
- else
- {
-#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
- double r = a;
- r *= times;
- r /= divisor;
- r = floor(r+.5);
-
- /* A png_fixed_point is a 32-bit integer. */
- if (r <= 2147483647. && r >= -2147483648.)
- {
- *res = (png_fixed_point)r;
- return 1;
- }
-#else
- int negative = 0;
- png_uint_32 A, T, D;
- png_uint_32 s16, s32, s00;
-
- if (a < 0)
- negative = 1, A = -a;
- else
- A = a;
-
- if (times < 0)
- negative = !negative, T = -times;
- else
- T = times;
-
- if (divisor < 0)
- negative = !negative, D = -divisor;
- else
- D = divisor;
-
- /* Following can't overflow because the arguments only
- * have 31 bits each, however the result may be 32 bits.
- */
- s16 = (A >> 16) * (T & 0xffff) +
- (A & 0xffff) * (T >> 16);
- /* Can't overflow because the a*times bit is only 30
- * bits at most.
- */
- s32 = (A >> 16) * (T >> 16) + (s16 >> 16);
- s00 = (A & 0xffff) * (T & 0xffff);
-
- s16 = (s16 & 0xffff) << 16;
- s00 += s16;
-
- if (s00 < s16)
- ++s32; /* carry */
-
- if (s32 < D) /* else overflow */
- {
- /* s32.s00 is now the 64-bit product, do a standard
- * division, we know that s32 < D, so the maximum
- * required shift is 31.
- */
- int bitshift = 32;
- png_fixed_point result = 0; /* NOTE: signed */
-
- while (--bitshift >= 0)
- {
- png_uint_32 d32, d00;
-
- if (bitshift > 0)
- d32 = D >> (32-bitshift), d00 = D << bitshift;
-
- else
- d32 = 0, d00 = D;
-
- if (s32 > d32)
- {
- if (s00 < d00) --s32; /* carry */
- s32 -= d32, s00 -= d00, result += 1<<bitshift;
- }
-
- else
- if (s32 == d32 && s00 >= d00)
- s32 = 0, s00 -= d00, result += 1<<bitshift;
- }
-
- /* Handle the rounding. */
- if (s00 >= (D >> 1))
- ++result;
-
- if (negative)
- result = -result;
-
- /* Check for overflow. */
- if ((negative && result <= 0) || (!negative && result >= 0))
- {
- *res = result;
- return 1;
- }
- }
-#endif
- }
- }
-
- return 0;
-}
-#endif /* READ_GAMMA || INCH_CONVERSIONS */
-
-#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_INCH_CONVERSIONS_SUPPORTED)
-/* The following is for when the caller doesn't much care about the
- * result.
- */
-png_fixed_point
-png_muldiv_warn(png_structp png_ptr, png_fixed_point a, png_int_32 times,
- png_int_32 divisor)
-{
- png_fixed_point result;
-
- if (png_muldiv(&result, a, times, divisor))
- return result;
-
- png_warning(png_ptr, "fixed point overflow ignored");
- return 0;
-}
-#endif
-
-#ifdef PNG_READ_GAMMA_SUPPORTED /* more fixed point functions for gammma */
-/* Calculate a reciprocal, return 0 on div-by-zero or overflow. */
-png_fixed_point
-png_reciprocal(png_fixed_point a)
-{
-#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
- double r = floor(1E10/a+.5);
-
- if (r <= 2147483647. && r >= -2147483648.)
- return (png_fixed_point)r;
-#else
- png_fixed_point res;
-
- if (png_muldiv(&res, 100000, 100000, a))
- return res;
-#endif
-
- return 0; /* error/overflow */
-}
-
-/* A local convenience routine. */
-static png_fixed_point
-png_product2(png_fixed_point a, png_fixed_point b)
-{
- /* The required result is 1/a * 1/b; the following preserves accuracy. */
-#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
- double r = a * 1E-5;
- r *= b;
- r = floor(r+.5);
-
- if (r <= 2147483647. && r >= -2147483648.)
- return (png_fixed_point)r;
-#else
- png_fixed_point res;
-
- if (png_muldiv(&res, a, b, 100000))
- return res;
-#endif
-
- return 0; /* overflow */
-}
-
-/* The inverse of the above. */
-png_fixed_point
-png_reciprocal2(png_fixed_point a, png_fixed_point b)
-{
- /* The required result is 1/a * 1/b; the following preserves accuracy. */
-#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
- double r = 1E15/a;
- r /= b;
- r = floor(r+.5);
-
- if (r <= 2147483647. && r >= -2147483648.)
- return (png_fixed_point)r;
-#else
- /* This may overflow because the range of png_fixed_point isn't symmetric,
- * but this API is only used for the product of file and screen gamma so it
- * doesn't matter that the smallest number it can produce is 1/21474, not
- * 1/100000
- */
- png_fixed_point res = png_product2(a, b);
-
- if (res != 0)
- return png_reciprocal(res);
-#endif
-
- return 0; /* overflow */
-}
-#endif /* READ_GAMMA */
-
-#ifdef PNG_CHECK_cHRM_SUPPORTED
-/* Added at libpng version 1.2.34 (Dec 8, 2008) and 1.4.0 (Jan 2,
- * 2010: moved from pngset.c) */
-/*
- * Multiply two 32-bit numbers, V1 and V2, using 32-bit
- * arithmetic, to produce a 64-bit result in the HI/LO words.
- *
- * A B
- * x C D
- * ------
- * AD || BD
- * AC || CB || 0
- *
- * where A and B are the high and low 16-bit words of V1,
- * C and D are the 16-bit words of V2, AD is the product of
- * A and D, and X || Y is (X << 16) + Y.
-*/
-
-void /* PRIVATE */
-png_64bit_product (long v1, long v2, unsigned long *hi_product,
- unsigned long *lo_product)
-{
- int a, b, c, d;
- long lo, hi, x, y;
-
- a = (v1 >> 16) & 0xffff;
- b = v1 & 0xffff;
- c = (v2 >> 16) & 0xffff;
- d = v2 & 0xffff;
-
- lo = b * d; /* BD */
- x = a * d + c * b; /* AD + CB */
- y = ((lo >> 16) & 0xffff) + x;
-
- lo = (lo & 0xffff) | ((y & 0xffff) << 16);
- hi = (y >> 16) & 0xffff;
-
- hi += a * c; /* AC */
-
- *hi_product = (unsigned long)hi;
- *lo_product = (unsigned long)lo;
-}
-#endif /* CHECK_cHRM */
-
-#ifdef PNG_READ_GAMMA_SUPPORTED /* gamma table code */
-#ifndef PNG_FLOATING_ARITHMETIC_SUPPORTED
-/* Fixed point gamma.
- *
- * To calculate gamma this code implements fast log() and exp() calls using only
- * fixed point arithmetic. This code has sufficient precision for either 8-bit
- * or 16-bit sample values.
- *
- * The tables used here were calculated using simple 'bc' programs, but C double
- * precision floating point arithmetic would work fine. The programs are given
- * at the head of each table.
- *
- * 8-bit log table
- * This is a table of -log(value/255)/log(2) for 'value' in the range 128 to
- * 255, so it's the base 2 logarithm of a normalized 8-bit floating point
- * mantissa. The numbers are 32-bit fractions.
- */
-static png_uint_32
-png_8bit_l2[128] =
-{
-# ifdef PNG_DO_BC
- for (i=128;i<256;++i) { .5 - l(i/255)/l(2)*65536*65536; }
-# else
- 4270715492U, 4222494797U, 4174646467U, 4127164793U, 4080044201U, 4033279239U,
- 3986864580U, 3940795015U, 3895065449U, 3849670902U, 3804606499U, 3759867474U,
- 3715449162U, 3671346997U, 3627556511U, 3584073329U, 3540893168U, 3498011834U,
- 3455425220U, 3413129301U, 3371120137U, 3329393864U, 3287946700U, 3246774933U,
- 3205874930U, 3165243125U, 3124876025U, 3084770202U, 3044922296U, 3005329011U,
- 2965987113U, 2926893432U, 2888044853U, 2849438323U, 2811070844U, 2772939474U,
- 2735041326U, 2697373562U, 2659933400U, 2622718104U, 2585724991U, 2548951424U,
- 2512394810U, 2476052606U, 2439922311U, 2404001468U, 2368287663U, 2332778523U,
- 2297471715U, 2262364947U, 2227455964U, 2192742551U, 2158222529U, 2123893754U,
- 2089754119U, 2055801552U, 2022034013U, 1988449497U, 1955046031U, 1921821672U,
- 1888774511U, 1855902668U, 1823204291U, 1790677560U, 1758320682U, 1726131893U,
- 1694109454U, 1662251657U, 1630556815U, 1599023271U, 1567649391U, 1536433567U,
- 1505374214U, 1474469770U, 1443718700U, 1413119487U, 1382670639U, 1352370686U,
- 1322218179U, 1292211689U, 1262349810U, 1232631153U, 1203054352U, 1173618059U,
- 1144320946U, 1115161701U, 1086139034U, 1057251672U, 1028498358U, 999877854U,
- 971388940U, 943030410U, 914801076U, 886699767U, 858725327U, 830876614U,
- 803152505U, 775551890U, 748073672U, 720716771U, 693480120U, 666362667U,
- 639363374U, 612481215U, 585715177U, 559064263U, 532527486U, 506103872U,
- 479792461U, 453592303U, 427502463U, 401522014U, 375650043U, 349885648U,
- 324227938U, 298676034U, 273229066U, 247886176U, 222646516U, 197509248U,
- 172473545U, 147538590U, 122703574U, 97967701U, 73330182U, 48790236U,
- 24347096U, 0U
-# endif
-
-#if 0
- /* The following are the values for 16-bit tables - these work fine for the
- * 8-bit conversions but produce very slightly larger errors in the 16-bit
- * log (about 1.2 as opposed to 0.7 absolute error in the final value). To
- * use these all the shifts below must be adjusted appropriately.
- */
- 65166, 64430, 63700, 62976, 62257, 61543, 60835, 60132, 59434, 58741, 58054,
- 57371, 56693, 56020, 55352, 54689, 54030, 53375, 52726, 52080, 51439, 50803,
- 50170, 49542, 48918, 48298, 47682, 47070, 46462, 45858, 45257, 44661, 44068,
- 43479, 42894, 42312, 41733, 41159, 40587, 40020, 39455, 38894, 38336, 37782,
- 37230, 36682, 36137, 35595, 35057, 34521, 33988, 33459, 32932, 32408, 31887,
- 31369, 30854, 30341, 29832, 29325, 28820, 28319, 27820, 27324, 26830, 26339,
- 25850, 25364, 24880, 24399, 23920, 23444, 22970, 22499, 22029, 21562, 21098,
- 20636, 20175, 19718, 19262, 18808, 18357, 17908, 17461, 17016, 16573, 16132,
- 15694, 15257, 14822, 14390, 13959, 13530, 13103, 12678, 12255, 11834, 11415,
- 10997, 10582, 10168, 9756, 9346, 8937, 8531, 8126, 7723, 7321, 6921, 6523,
- 6127, 5732, 5339, 4947, 4557, 4169, 3782, 3397, 3014, 2632, 2251, 1872, 1495,
- 1119, 744, 372
-#endif
-};
-
-PNG_STATIC png_int_32
-png_log8bit(unsigned int x)
-{
- unsigned int lg2 = 0;
- /* Each time 'x' is multiplied by 2, 1 must be subtracted off the final log,
- * because the log is actually negate that means adding 1. The final
- * returned value thus has the range 0 (for 255 input) to 7.994 (for 1
- * input), return 7.99998 for the overflow (log 0) case - so the result is
- * always at most 19 bits.
- */
- if ((x &= 0xff) == 0)
- return 0xffffffff;
-
- if ((x & 0xf0) == 0)
- lg2 = 4, x <<= 4;
-
- if ((x & 0xc0) == 0)
- lg2 += 2, x <<= 2;
-
- if ((x & 0x80) == 0)
- lg2 += 1, x <<= 1;
-
- /* result is at most 19 bits, so this cast is safe: */
- return (png_int_32)((lg2 << 16) + ((png_8bit_l2[x-128]+32768)>>16));
-}
-
-/* The above gives exact (to 16 binary places) log2 values for 8-bit images,
- * for 16-bit images we use the most significant 8 bits of the 16-bit value to
- * get an approximation then multiply the approximation by a correction factor
- * determined by the remaining up to 8 bits. This requires an additional step
- * in the 16-bit case.
- *
- * We want log2(value/65535), we have log2(v'/255), where:
- *
- * value = v' * 256 + v''
- * = v' * f
- *
- * So f is value/v', which is equal to (256+v''/v') since v' is in the range 128
- * to 255 and v'' is in the range 0 to 255 f will be in the range 256 to less
- * than 258. The final factor also needs to correct for the fact that our 8-bit
- * value is scaled by 255, whereas the 16-bit values must be scaled by 65535.
- *
- * This gives a final formula using a calculated value 'x' which is value/v' and
- * scaling by 65536 to match the above table:
- *
- * log2(x/257) * 65536
- *
- * Since these numbers are so close to '1' we can use simple linear
- * interpolation between the two end values 256/257 (result -368.61) and 258/257
- * (result 367.179). The values used below are scaled by a further 64 to give
- * 16-bit precision in the interpolation:
- *
- * Start (256): -23591
- * Zero (257): 0
- * End (258): 23499
- */
-PNG_STATIC png_int_32
-png_log16bit(png_uint_32 x)
-{
- unsigned int lg2 = 0;
-
- /* As above, but now the input has 16 bits. */
- if ((x &= 0xffff) == 0)
- return 0xffffffff;
-
- if ((x & 0xff00) == 0)
- lg2 = 8, x <<= 8;
-
- if ((x & 0xf000) == 0)
- lg2 += 4, x <<= 4;
-
- if ((x & 0xc000) == 0)
- lg2 += 2, x <<= 2;
-
- if ((x & 0x8000) == 0)
- lg2 += 1, x <<= 1;
-
- /* Calculate the base logarithm from the top 8 bits as a 28-bit fractional
- * value.
- */
- lg2 <<= 28;
- lg2 += (png_8bit_l2[(x>>8)-128]+8) >> 4;
-
- /* Now we need to interpolate the factor, this requires a division by the top
- * 8 bits. Do this with maximum precision.
- */
- x = ((x << 16) + (x >> 9)) / (x >> 8);
-
- /* Since we divided by the top 8 bits of 'x' there will be a '1' at 1<<24,
- * the value at 1<<16 (ignoring this) will be 0 or 1; this gives us exactly
- * 16 bits to interpolate to get the low bits of the result. Round the
- * answer. Note that the end point values are scaled by 64 to retain overall
- * precision and that 'lg2' is current scaled by an extra 12 bits, so adjust
- * the overall scaling by 6-12. Round at every step.
- */
- x -= 1U << 24;
-
- if (x <= 65536U) /* <= '257' */
- lg2 += ((23591U * (65536U-x)) + (1U << (16+6-12-1))) >> (16+6-12);
-
- else
- lg2 -= ((23499U * (x-65536U)) + (1U << (16+6-12-1))) >> (16+6-12);
-
- /* Safe, because the result can't have more than 20 bits: */
- return (png_int_32)((lg2 + 2048) >> 12);
-}
-
-/* The 'exp()' case must invert the above, taking a 20-bit fixed point
- * logarithmic value and returning a 16 or 8-bit number as appropriate. In
- * each case only the low 16 bits are relevant - the fraction - since the
- * integer bits (the top 4) simply determine a shift.
- *
- * The worst case is the 16-bit distinction between 65535 and 65534, this
- * requires perhaps spurious accuracy in the decoding of the logarithm to
- * distinguish log2(65535/65534.5) - 10^-5 or 17 bits. There is little chance
- * 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
- * top four fractional bits then multiplying in the remaining bits.
- */
-static png_uint_32
-png_32bit_exp[16] =
-{
-# ifdef PNG_DO_BC
- for (i=0;i<16;++i) { .5 + e(-i/16*l(2))*2^32; }
-# else
- /* NOTE: the first entry is deliberately set to the maximum 32-bit value. */
- 4294967295U, 4112874773U, 3938502376U, 3771522796U, 3611622603U, 3458501653U,
- 3311872529U, 3171459999U, 3037000500U, 2908241642U, 2784941738U, 2666869345U,
- 2553802834U, 2445529972U, 2341847524U, 2242560872U
-# endif
-};
-
-/* Adjustment table; provided to explain the numbers in the code below. */
-#ifdef PNG_DO_BC
-for (i=11;i>=0;--i){ print i, " ", (1 - e(-(2^i)/65536*l(2))) * 2^(32-i), "\n"}
- 11 44937.64284865548751208448
- 10 45180.98734845585101160448
- 9 45303.31936980687359311872
- 8 45364.65110595323018870784
- 7 45395.35850361789624614912
- 6 45410.72259715102037508096
- 5 45418.40724413220722311168
- 4 45422.25021786898173001728
- 3 45424.17186732298419044352
- 2 45425.13273269940811464704
- 1 45425.61317555035558641664
- 0 45425.85339951654943850496
-#endif
-
-PNG_STATIC png_uint_32
-png_exp(png_fixed_point x)
-{
- if (x > 0 && x <= 0xfffff) /* Else overflow or zero (underflow) */
- {
- /* Obtain a 4-bit approximation */
- png_uint_32 e = png_32bit_exp[(x >> 12) & 0xf];
-
- /* Incorporate the low 12 bits - these decrease the returned value by
- * multiplying by a number less than 1 if the bit is set. The multiplier
- * is determined by the above table and the shift. Notice that the values
- * converge on 45426 and this is used to allow linear interpolation of the
- * low bits.
- */
- if (x & 0x800)
- e -= (((e >> 16) * 44938U) + 16U) >> 5;
-
- if (x & 0x400)
- e -= (((e >> 16) * 45181U) + 32U) >> 6;
-
- if (x & 0x200)
- e -= (((e >> 16) * 45303U) + 64U) >> 7;
-
- if (x & 0x100)
- e -= (((e >> 16) * 45365U) + 128U) >> 8;
-
- if (x & 0x080)
- e -= (((e >> 16) * 45395U) + 256U) >> 9;
-
- if (x & 0x040)
- e -= (((e >> 16) * 45410U) + 512U) >> 10;
-
- /* And handle the low 6 bits in a single block. */
- e -= (((e >> 16) * 355U * (x & 0x3fU)) + 256U) >> 9;
-
- /* Handle the upper bits of x. */
- e >>= x >> 16;
- return e;
- }
-
- /* Check for overflow */
- if (x <= 0)
- return png_32bit_exp[0];
-
- /* Else underflow */
- return 0;
-}
-
-PNG_STATIC png_byte
-png_exp8bit(png_fixed_point lg2)
-{
- /* Get a 32-bit value: */
- png_uint_32 x = png_exp(lg2);
-
- /* Convert the 32-bit value to 0..255 by multiplying by 256-1, note that the
- * second, rounding, step can't overflow because of the first, subtraction,
- * step.
- */
- x -= x >> 8;
- return (png_byte)((x + 0x7fffffU) >> 24);
-}
-
-PNG_STATIC png_uint_16
-png_exp16bit(png_fixed_point lg2)
-{
- /* Get a 32-bit value: */
- png_uint_32 x = png_exp(lg2);
-
- /* Convert the 32-bit value to 0..65535 by multiplying by 65536-1: */
- x -= x >> 16;
- return (png_uint_16)((x + 32767U) >> 16);
-}
-#endif /* FLOATING_ARITHMETIC */
-
-png_byte
-png_gamma_8bit_correct(unsigned int value, png_fixed_point gamma_val)
-{
- if (value > 0 && value < 255)
- {
-# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
- double r = floor(255*pow(value/255.,gamma_val*.00001)+.5);
- return (png_byte)r;
-# else
- png_int_32 lg2 = png_log8bit(value);
- png_fixed_point res;
-
- if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1))
- return png_exp8bit(res);
-
- /* Overflow. */
- value = 0;
-# endif
- }
-
- return (png_byte)value;
-}
-
-png_uint_16
-png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val)
-{
- if (value > 0 && value < 65535)
- {
-# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
- double r = floor(65535*pow(value/65535.,gamma_val*.00001)+.5);
- return (png_uint_16)r;
-# else
- png_int_32 lg2 = png_log16bit(value);
- png_fixed_point res;
-
- if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1))
- return png_exp16bit(res);
-
- /* Overflow. */
- value = 0;
-# endif
- }
-
- return (png_uint_16)value;
-}
-
-/* This does the right thing based on the bit_depth field of the
- * png_struct, interpreting values as 8-bit or 16-bit. While the result
- * is nominally a 16-bit value if bit depth is 8 then the result is
- * 8-bit (as are the arguments.)
- */
-png_uint_16 /* PRIVATE */
-png_gamma_correct(png_structp png_ptr, unsigned int value,
- png_fixed_point gamma_val)
-{
- if (png_ptr->bit_depth == 8)
- return png_gamma_8bit_correct(value, gamma_val);
-
- else
- return png_gamma_16bit_correct(value, gamma_val);
-}
-
-/* This is the shared test on whether a gamma value is 'significant' - whether
- * it is worth doing gamma correction.
- */
-int /* PRIVATE */
-png_gamma_significant(png_fixed_point gamma_val)
-{
- return gamma_val < PNG_FP_1 - PNG_GAMMA_THRESHOLD_FIXED ||
- gamma_val > PNG_FP_1 + PNG_GAMMA_THRESHOLD_FIXED;
-}
-
-/* Internal function to build a single 16-bit table - the table consists of
- * 'num' 256-entry subtables, where 'num' is determined by 'shift' - the amount
- * to shift the input values right (or 16-number_of_signifiant_bits).
- *
- * The caller is responsible for ensuring that the table gets cleaned up on
- * png_error (i.e. if one of the mallocs below fails) - i.e. the *table argument
- * should be somewhere that will be cleaned.
- */
-static void
-png_build_16bit_table(png_structp png_ptr, png_uint_16pp *ptable,
- PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
-{
- /* Various values derived from 'shift': */
- PNG_CONST unsigned int num = 1U << (8U - shift);
- PNG_CONST unsigned int max = (1U << (16U - shift))-1U;
- PNG_CONST unsigned int max_by_2 = 1U << (15U-shift);
- unsigned int i;
-
- png_uint_16pp table = *ptable =
- (png_uint_16pp)png_calloc(png_ptr, num * png_sizeof(png_uint_16p));
-
- for (i = 0; i < num; i++)
- {
- png_uint_16p sub_table = table[i] =
- (png_uint_16p)png_malloc(png_ptr, 256 * png_sizeof(png_uint_16));
-
- /* The 'threshold' test is repeated here because it can arise for one of
- * the 16-bit tables even if the others don't hit it.
- */
- if (png_gamma_significant(gamma_val))
- {
- /* The old code would overflow at the end and this would cause the
- * 'pow' function to return a result >1, resulting in an
- * arithmetic error. This code follows the spec exactly; ig is
- * the recovered input sample, it always has 8-16 bits.
- *
- * We want input * 65535/max, rounded, the arithmetic fits in 32
- * bits (unsigned) so long as max <= 32767.
- */
- unsigned int j;
- for (j = 0; j < 256; j++)
- {
- png_uint_32 ig = (j << (8-shift)) + i;
-# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
- /* Inline the 'max' scaling operation: */
- double d = floor(65535*pow(ig/(double)max, gamma_val*.00001)+.5);
- sub_table[j] = (png_uint_16)d;
-# else
- if (shift)
- ig = (ig * 65535U + max_by_2)/max;
-
- sub_table[j] = png_gamma_16bit_correct(ig, gamma_val);
-# endif
- }
- }
- else
- {
- /* We must still build a table, but do it the fast way. */
- unsigned int j;
-
- for (j = 0; j < 256; j++)
- {
- png_uint_32 ig = (j << (8-shift)) + i;
-
- if (shift)
- ig = (ig * 65535U + max_by_2)/max;
-
- sub_table[j] = (png_uint_16)ig;
- }
- }
- }
-}
-
-/* NOTE: this function expects the *inverse* of the overall gamma transformation
- * required.
- */
-static void
-png_build_16to8_table(png_structp png_ptr, png_uint_16pp *ptable,
- PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
-{
- PNG_CONST unsigned int num = 1U << (8U - shift);
- PNG_CONST unsigned int max = (1U << (16U - shift))-1U;
- unsigned int i;
- png_uint_32 last;
-
- png_uint_16pp table = *ptable =
- (png_uint_16pp)png_calloc(png_ptr, num * png_sizeof(png_uint_16p));
-
- /* 'num' is the number of tables and also the number of low bits of the
- * input 16-bit value used to select a table. Each table is itself indexed
- * by the high 8 bits of the value.
- */
- for (i = 0; i < num; i++)
- table[i] = (png_uint_16p)png_malloc(png_ptr,
- 256 * png_sizeof(png_uint_16));
-
- /* 'gamma_val' is set to the reciprocal of the value calculated above, so
- * pow(out,g) is an *input* value. 'last' is the last input value set.
- *
- * In the loop 'i' is used to find output values. Since the output is
- * 8-bit there are only 256 possible values. The tables are set up to
- * select the closest possible output value for each input by finding
- * the input value at the boundary between each pair of output values
- * and filling the table up to that boundary with the lower output
- * value.
- *
- * The boundary values are 0.5,1.5..253.5,254.5. Since these are 9-bit
- * values the code below uses a 16-bit value in i; the values start at
- * 128.5 (for 0.5) and step by 257, for a total of 254 values (the last
- * entries are filled with 255). Start i at 128 and fill all 'last'
- * table entries <= 'max'
- */
- last = 0;
- for (i = 0; i < 255; ++i) /* 8-bit output value */
- {
- /* Find the corresponding maximum input value */
- png_uint_16 out = (png_uint_16)(i * 257U); /* 16-bit output value */
-
- /* Find the boundary value in 16 bits: */
- png_uint_32 bound = png_gamma_16bit_correct(out+128U, gamma_val);
-
- /* Adjust (round) to (16-shift) bits: */
- bound = (bound * max + 32768U)/65535U + 1U;
-
- while (last < bound)
- {
- table[last & (0xffU >> shift)][last >> (8U - shift)] = out;
- last++;
- }
- }
-
- /* And fill in the final entries. */
- while (last < (num << 8))
- {
- table[last & (0xff >> shift)][last >> (8U - shift)] = 65535U;
- last++;
- }
-}
-
-/* Build a single 8-bit table: same as the 16-bit case but much simpler (and
- * typically much faster). Note that libpng currently does no sBIT processing
- * (apparently contrary to the spec) so a 256-entry table is always generated.
- */
-static void
-png_build_8bit_table(png_structp png_ptr, png_bytepp ptable,
- PNG_CONST png_fixed_point gamma_val)
-{
- unsigned int i;
- png_bytep table = *ptable = (png_bytep)png_malloc(png_ptr, 256);
-
- if (png_gamma_significant(gamma_val)) for (i=0; i<256; i++)
- table[i] = png_gamma_8bit_correct(i, gamma_val);
-
- else for (i=0; i<256; ++i)
- table[i] = (png_byte)i;
-}
-
-/* Used from png_read_destroy and below to release the memory used by the gamma
- * tables.
- */
-void /* PRIVATE */
-png_destroy_gamma_table(png_structp png_ptr)
-{
- png_free(png_ptr, png_ptr->gamma_table);
- png_ptr->gamma_table = NULL;
-
- if (png_ptr->gamma_16_table != NULL)
- {
- int i;
- int istop = (1 << (8 - png_ptr->gamma_shift));
- for (i = 0; i < istop; i++)
- {
- png_free(png_ptr, png_ptr->gamma_16_table[i]);
- }
- png_free(png_ptr, png_ptr->gamma_16_table);
- png_ptr->gamma_16_table = NULL;
- }
-
-#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
- defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
- defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
- png_free(png_ptr, png_ptr->gamma_from_1);
- png_ptr->gamma_from_1 = NULL;
- png_free(png_ptr, png_ptr->gamma_to_1);
- png_ptr->gamma_to_1 = NULL;
-
- if (png_ptr->gamma_16_from_1 != NULL)
- {
- int i;
- int istop = (1 << (8 - png_ptr->gamma_shift));
- for (i = 0; i < istop; i++)
- {
- png_free(png_ptr, png_ptr->gamma_16_from_1[i]);
- }
- png_free(png_ptr, png_ptr->gamma_16_from_1);
- png_ptr->gamma_16_from_1 = NULL;
- }
- if (png_ptr->gamma_16_to_1 != NULL)
- {
- int i;
- int istop = (1 << (8 - png_ptr->gamma_shift));
- for (i = 0; i < istop; i++)
- {
- png_free(png_ptr, png_ptr->gamma_16_to_1[i]);
- }
- png_free(png_ptr, png_ptr->gamma_16_to_1);
- png_ptr->gamma_16_to_1 = NULL;
- }
-#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
-}
-
-/* We build the 8- or 16-bit gamma tables here. Note that for 16-bit
- * tables, we don't make a full table if we are reducing to 8-bit in
- * the future. Note also how the gamma_16 tables are segmented so that
- * we don't need to allocate > 64K chunks for a full 16-bit table.
- */
-void /* PRIVATE */
-png_build_gamma_table(png_structp png_ptr, int bit_depth)
-{
- png_debug(1, "in png_build_gamma_table");
-
- /* Remove any existing table; this copes with multiple calls to
- * png_read_update_info. The warning is because building the gamma tables
- * multiple times is a performance hit - it's harmless but the ability to call
- * png_read_update_info() multiple times is new in 1.5.6 so it seems sensible
- * to warn if the app introduces such a hit.
- */
- if (png_ptr->gamma_table != NULL || png_ptr->gamma_16_table != NULL)
- {
- png_warning(png_ptr, "gamma table being rebuilt");
- png_destroy_gamma_table(png_ptr);
- }
-
- if (bit_depth <= 8)
- {
- png_build_8bit_table(png_ptr, &png_ptr->gamma_table,
- png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->gamma,
- png_ptr->screen_gamma) : PNG_FP_1);
-
-#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
- defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
- defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
- if (png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY))
- {
- png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1,
- png_reciprocal(png_ptr->gamma));
-
- png_build_8bit_table(png_ptr, &png_ptr->gamma_from_1,
- png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
- png_ptr->gamma/* Probably doing rgb_to_gray */);
- }
-#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
- }
- else
- {
- png_byte shift, sig_bit;
-
- if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
- {
- sig_bit = png_ptr->sig_bit.red;
-
- if (png_ptr->sig_bit.green > sig_bit)
- sig_bit = png_ptr->sig_bit.green;
-
- if (png_ptr->sig_bit.blue > sig_bit)
- sig_bit = png_ptr->sig_bit.blue;
- }
- else
- sig_bit = png_ptr->sig_bit.gray;
-
- /* 16-bit gamma code uses this equation:
- *
- * ov = table[(iv & 0xff) >> gamma_shift][iv >> 8]
- *
- * Where 'iv' is the input color value and 'ov' is the output value -
- * pow(iv, gamma).
- *
- * Thus the gamma table consists of up to 256 256-entry tables. The table
- * is selected by the (8-gamma_shift) most significant of the low 8 bits of
- * the color value then indexed by the upper 8 bits:
- *
- * table[low bits][high 8 bits]
- *
- * So the table 'n' corresponds to all those 'iv' of:
- *
- * <all high 8-bit values><n << gamma_shift>..<(n+1 << gamma_shift)-1>
- *
- */
- if (sig_bit > 0 && sig_bit < 16U)
- shift = (png_byte)(16U - sig_bit); /* shift == insignificant bits */
-
- else
- shift = 0; /* keep all 16 bits */
-
- if (png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8))
- {
- /* PNG_MAX_GAMMA_8 is the number of bits to keep - effectively
- * the significant bits in the *input* when the output will
- * eventually be 8 bits. By default it is 11.
- */
- if (shift < (16U - PNG_MAX_GAMMA_8))
- shift = (16U - PNG_MAX_GAMMA_8);
- }
-
- if (shift > 8U)
- shift = 8U; /* Guarantees at least one table! */
-
- png_ptr->gamma_shift = shift;
-
-#ifdef PNG_16BIT_SUPPORTED
- /* NOTE: prior to 1.5.4 this test used to include PNG_BACKGROUND (now
- * PNG_COMPOSE). This effectively smashed the background calculation for
- * 16-bit output because the 8-bit table assumes the result will be reduced
- * to 8 bits.
- */
- if (png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8))
-#endif
- png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift,
- png_ptr->screen_gamma > 0 ? png_product2(png_ptr->gamma,
- png_ptr->screen_gamma) : PNG_FP_1);
-
-#ifdef PNG_16BIT_SUPPORTED
- else
- png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift,
- png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->gamma,
- png_ptr->screen_gamma) : PNG_FP_1);
-#endif
-
-#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
- defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
- defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
- if (png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY))
- {
- png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift,
- png_reciprocal(png_ptr->gamma));
-
- /* Notice that the '16 from 1' table should be full precision, however
- * the lookup on this table still uses gamma_shift, so it can't be.
- * TODO: fix this.
- */
- png_build_16bit_table(png_ptr, &png_ptr->gamma_16_from_1, shift,
- png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
- png_ptr->gamma/* Probably doing rgb_to_gray */);
- }
-#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
- }
-}
-#endif /* READ_GAMMA */
-#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
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