1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
|
// ==========================================================
// Display routines
//
// Design and implementation by
// - Hervé Drolon (drolon@infonie.fr)
//
// This file is part of FreeImage 3
//
// COVERED CODE IS PROVIDED UNDER THIS LICENSE ON AN "AS IS" BASIS, WITHOUT WARRANTY
// OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, WITHOUT LIMITATION, WARRANTIES
// THAT THE COVERED CODE IS FREE OF DEFECTS, MERCHANTABLE, FIT FOR A PARTICULAR PURPOSE
// OR NON-INFRINGING. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE COVERED
// CODE IS WITH YOU. SHOULD ANY COVERED CODE PROVE DEFECTIVE IN ANY RESPECT, YOU (NOT
// THE INITIAL DEVELOPER OR ANY OTHER CONTRIBUTOR) ASSUME THE COST OF ANY NECESSARY
// SERVICING, REPAIR OR CORRECTION. THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL
// PART OF THIS LICENSE. NO USE OF ANY COVERED CODE IS AUTHORIZED HEREUNDER EXCEPT UNDER
// THIS DISCLAIMER.
//
// Use at your own risk!
// ==========================================================
#include "../stdafx.h"
/**
@brief Composite a foreground image against a background color or a background image.
The equation for computing a composited sample value is:<br>
output = alpha * foreground + (1-alpha) * background<br>
where alpha and the input and output sample values are expressed as fractions in the range 0 to 1.
For colour images, the computation is done separately for R, G, and B samples.
@param fg Foreground image
@param useFileBkg If TRUE and a file background is present, use it as the background color
@param appBkColor If not equal to NULL, and useFileBkg is FALSE, use this color as the background color
@param bg If not equal to NULL and useFileBkg is FALSE and appBkColor is NULL, use this as the background image
@return Returns the composite image if successful, returns NULL otherwise
@see FreeImage_IsTransparent, FreeImage_HasBackgroundColor
*/
FIBITMAP * DLL_CALLCONV
FreeImage_Composite(FIBITMAP *fg, BOOL useFileBkg, RGBQUAD *appBkColor, FIBITMAP *bg) {
if(!FreeImage_HasPixels(fg)) return NULL;
int width = FreeImage_GetWidth(fg);
int height = FreeImage_GetHeight(fg);
int bpp = FreeImage_GetBPP(fg);
if((bpp != 8) && (bpp != 32))
return NULL;
if(bg) {
int bg_width = FreeImage_GetWidth(bg);
int bg_height = FreeImage_GetHeight(bg);
int bg_bpp = FreeImage_GetBPP(bg);
if((bg_width != width) || (bg_height != height) || (bg_bpp != 24))
return NULL;
}
int bytespp = (bpp == 8) ? 1 : 4;
int x, y, c;
BYTE alpha = 0, not_alpha;
BYTE index;
RGBQUAD fgc; // foreground color
RGBQUAD bkc; // background color
memset(&fgc, 0, sizeof(RGBQUAD));
memset(&bkc, 0, sizeof(RGBQUAD));
// allocate the composite image
FIBITMAP *composite = FreeImage_Allocate(width, height, 24, FI_RGBA_RED_MASK, FI_RGBA_GREEN_MASK, FI_RGBA_BLUE_MASK);
if(!composite) return NULL;
// get the palette
RGBQUAD *pal = FreeImage_GetPalette(fg);
// retrieve the alpha table from the foreground image
BOOL bIsTransparent = FreeImage_IsTransparent(fg);
BYTE *trns = FreeImage_GetTransparencyTable(fg);
// retrieve the background color from the foreground image
BOOL bHasBkColor = FALSE;
if(useFileBkg && FreeImage_HasBackgroundColor(fg)) {
FreeImage_GetBackgroundColor(fg, &bkc);
bHasBkColor = TRUE;
} else {
// no file background color
// use application background color ?
if(appBkColor) {
memcpy(&bkc, appBkColor, sizeof(RGBQUAD));
bHasBkColor = TRUE;
}
// use background image ?
else if(bg) {
bHasBkColor = FALSE;
}
}
for(y = 0; y < height; y++) {
// foreground
BYTE *fg_bits = FreeImage_GetScanLine(fg, y);
// background
BYTE *bg_bits = FreeImage_GetScanLine(bg, y);
// composite image
BYTE *cp_bits = FreeImage_GetScanLine(composite, y);
for(x = 0; x < width; x++) {
// foreground color + alpha
if(bpp == 8) {
// get the foreground color
index = fg_bits[0];
memcpy(&fgc, &pal[index], sizeof(RGBQUAD));
// get the alpha
if(bIsTransparent) {
alpha = trns[index];
} else {
alpha = 255;
}
}
else if(bpp == 32) {
// get the foreground color
fgc.rgbBlue = fg_bits[FI_RGBA_BLUE];
fgc.rgbGreen = fg_bits[FI_RGBA_GREEN];
fgc.rgbRed = fg_bits[FI_RGBA_RED];
// get the alpha
alpha = fg_bits[FI_RGBA_ALPHA];
}
// background color
if(!bHasBkColor) {
if(bg) {
// get the background color from the background image
bkc.rgbBlue = bg_bits[FI_RGBA_BLUE];
bkc.rgbGreen = bg_bits[FI_RGBA_GREEN];
bkc.rgbRed = bg_bits[FI_RGBA_RED];
}
else {
// use a checkerboard pattern
c = (((y & 0x8) == 0) ^ ((x & 0x8) == 0)) * 192;
c = c ? c : 255;
bkc.rgbBlue = (BYTE)c;
bkc.rgbGreen = (BYTE)c;
bkc.rgbRed = (BYTE)c;
}
}
// composition
if(alpha == 0) {
// output = background
cp_bits[FI_RGBA_BLUE] = bkc.rgbBlue;
cp_bits[FI_RGBA_GREEN] = bkc.rgbGreen;
cp_bits[FI_RGBA_RED] = bkc.rgbRed;
}
else if(alpha == 255) {
// output = foreground
cp_bits[FI_RGBA_BLUE] = fgc.rgbBlue;
cp_bits[FI_RGBA_GREEN] = fgc.rgbGreen;
cp_bits[FI_RGBA_RED] = fgc.rgbRed;
}
else {
// output = alpha * foreground + (1-alpha) * background
not_alpha = (BYTE)~alpha;
cp_bits[FI_RGBA_BLUE] = (BYTE)((alpha * (WORD)fgc.rgbBlue + not_alpha * (WORD)bkc.rgbBlue) >> 8);
cp_bits[FI_RGBA_GREEN] = (BYTE)((alpha * (WORD)fgc.rgbGreen + not_alpha * (WORD)bkc.rgbGreen) >> 8);
cp_bits[FI_RGBA_RED] = (BYTE)((alpha * (WORD)fgc.rgbRed + not_alpha * (WORD)bkc.rgbRed) >> 8);
}
fg_bits += bytespp;
bg_bits += 3;
cp_bits += 3;
}
}
// copy metadata from src to dst
FreeImage_CloneMetadata(composite, fg);
return composite;
}
/**
Pre-multiplies a 32-bit image's red-, green- and blue channels with it's alpha channel
for to be used with e.g. the Windows GDI function AlphaBlend().
The transformation changes the red-, green- and blue channels according to the following equation:
channel(x, y) = channel(x, y) * alpha_channel(x, y) / 255
@param dib Input/Output dib to be premultiplied
@return Returns TRUE on success, FALSE otherwise (e.g. when the bitdepth of the source dib cannot be handled).
*/
BOOL DLL_CALLCONV
FreeImage_PremultiplyWithAlpha(FIBITMAP *dib) {
if (!FreeImage_HasPixels(dib)) return FALSE;
if ((FreeImage_GetBPP(dib) != 32) || (FreeImage_GetImageType(dib) != FIT_BITMAP)) {
return FALSE;
}
int width = FreeImage_GetWidth(dib);
int height = FreeImage_GetHeight(dib);
for(int y = 0; y < height; y++) {
BYTE *bits = FreeImage_GetScanLine(dib, y);
for (int x = 0; x < width; x++, bits += 4) {
const BYTE alpha = bits[FI_RGBA_ALPHA];
// slightly faster: care for two special cases
if(alpha == 0x00) {
// special case for alpha == 0x00
// color * 0x00 / 0xFF = 0x00
bits[FI_RGBA_BLUE] = 0x00;
bits[FI_RGBA_GREEN] = 0x00;
bits[FI_RGBA_RED] = 0x00;
} else if(alpha == 0xFF) {
// nothing to do for alpha == 0xFF
// color * 0xFF / 0xFF = color
continue;
} else {
bits[FI_RGBA_BLUE] = (BYTE)( (alpha * (WORD)bits[FI_RGBA_BLUE] + 127) / 255 );
bits[FI_RGBA_GREEN] = (BYTE)( (alpha * (WORD)bits[FI_RGBA_GREEN] + 127) / 255 );
bits[FI_RGBA_RED] = (BYTE)( (alpha * (WORD)bits[FI_RGBA_RED] + 127) / 255 );
}
}
}
return TRUE;
}
|
