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[wxWidgets.git] / src / png / pngwtran.c
1
2 /* pngwtran.c - transforms the data in a row for PNG writers
3 *
4 * Last changed in libpng 1.4.1 [February 25, 2010]
5 * Copyright (c) 1998-2010 Glenn Randers-Pehrson
6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
8 *
9 * This code is released under the libpng license.
10 * For conditions of distribution and use, see the disclaimer
11 * and license in png.h
12 */
13
14 #define PNG_NO_PEDANTIC_WARNINGS
15 #include "png.h"
16 #ifdef PNG_WRITE_SUPPORTED
17 #include "pngpriv.h"
18
19 /* Transform the data according to the user's wishes. The order of
20 * transformations is significant.
21 */
22 void /* PRIVATE */
23 png_do_write_transformations(png_structp png_ptr)
24 {
25 png_debug(1, "in png_do_write_transformations");
26
27 if (png_ptr == NULL)
28 return;
29
30 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
31 if (png_ptr->transformations & PNG_USER_TRANSFORM)
32 if (png_ptr->write_user_transform_fn != NULL)
33 (*(png_ptr->write_user_transform_fn)) /* User write transform
34 function */
35 (png_ptr, /* png_ptr */
36 &(png_ptr->row_info), /* row_info: */
37 /* png_uint_32 width; width of row */
38 /* png_uint_32 rowbytes; number of bytes in row */
39 /* png_byte color_type; color type of pixels */
40 /* png_byte bit_depth; bit depth of samples */
41 /* png_byte channels; number of channels (1-4) */
42 /* png_byte pixel_depth; bits per pixel (depth*channels) */
43 png_ptr->row_buf + 1); /* start of pixel data for row */
44 #endif
45 #ifdef PNG_WRITE_FILLER_SUPPORTED
46 if (png_ptr->transformations & PNG_FILLER)
47 png_do_strip_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,
48 png_ptr->flags);
49 #endif
50 #ifdef PNG_WRITE_PACKSWAP_SUPPORTED
51 if (png_ptr->transformations & PNG_PACKSWAP)
52 png_do_packswap(&(png_ptr->row_info), png_ptr->row_buf + 1);
53 #endif
54 #ifdef PNG_WRITE_PACK_SUPPORTED
55 if (png_ptr->transformations & PNG_PACK)
56 png_do_pack(&(png_ptr->row_info), png_ptr->row_buf + 1,
57 (png_uint_32)png_ptr->bit_depth);
58 #endif
59 #ifdef PNG_WRITE_SWAP_SUPPORTED
60 if (png_ptr->transformations & PNG_SWAP_BYTES)
61 png_do_swap(&(png_ptr->row_info), png_ptr->row_buf + 1);
62 #endif
63 #ifdef PNG_WRITE_SHIFT_SUPPORTED
64 if (png_ptr->transformations & PNG_SHIFT)
65 png_do_shift(&(png_ptr->row_info), png_ptr->row_buf + 1,
66 &(png_ptr->shift));
67 #endif
68 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
69 if (png_ptr->transformations & PNG_SWAP_ALPHA)
70 png_do_write_swap_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
71 #endif
72 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
73 if (png_ptr->transformations & PNG_INVERT_ALPHA)
74 png_do_write_invert_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
75 #endif
76 #ifdef PNG_WRITE_BGR_SUPPORTED
77 if (png_ptr->transformations & PNG_BGR)
78 png_do_bgr(&(png_ptr->row_info), png_ptr->row_buf + 1);
79 #endif
80 #ifdef PNG_WRITE_INVERT_SUPPORTED
81 if (png_ptr->transformations & PNG_INVERT_MONO)
82 png_do_invert(&(png_ptr->row_info), png_ptr->row_buf + 1);
83 #endif
84 }
85
86 #ifdef PNG_WRITE_PACK_SUPPORTED
87 /* Pack pixels into bytes. Pass the true bit depth in bit_depth. The
88 * row_info bit depth should be 8 (one pixel per byte). The channels
89 * should be 1 (this only happens on grayscale and paletted images).
90 */
91 void /* PRIVATE */
92 png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
93 {
94 png_debug(1, "in png_do_pack");
95
96 if (row_info->bit_depth == 8 &&
97 row_info->channels == 1)
98 {
99 switch ((int)bit_depth)
100 {
101 case 1:
102 {
103 png_bytep sp, dp;
104 int mask, v;
105 png_uint_32 i;
106 png_uint_32 row_width = row_info->width;
107
108 sp = row;
109 dp = row;
110 mask = 0x80;
111 v = 0;
112
113 for (i = 0; i < row_width; i++)
114 {
115 if (*sp != 0)
116 v |= mask;
117 sp++;
118 if (mask > 1)
119 mask >>= 1;
120 else
121 {
122 mask = 0x80;
123 *dp = (png_byte)v;
124 dp++;
125 v = 0;
126 }
127 }
128 if (mask != 0x80)
129 *dp = (png_byte)v;
130 break;
131 }
132 case 2:
133 {
134 png_bytep sp, dp;
135 int shift, v;
136 png_uint_32 i;
137 png_uint_32 row_width = row_info->width;
138
139 sp = row;
140 dp = row;
141 shift = 6;
142 v = 0;
143 for (i = 0; i < row_width; i++)
144 {
145 png_byte value;
146
147 value = (png_byte)(*sp & 0x03);
148 v |= (value << shift);
149 if (shift == 0)
150 {
151 shift = 6;
152 *dp = (png_byte)v;
153 dp++;
154 v = 0;
155 }
156 else
157 shift -= 2;
158 sp++;
159 }
160 if (shift != 6)
161 *dp = (png_byte)v;
162 break;
163 }
164 case 4:
165 {
166 png_bytep sp, dp;
167 int shift, v;
168 png_uint_32 i;
169 png_uint_32 row_width = row_info->width;
170
171 sp = row;
172 dp = row;
173 shift = 4;
174 v = 0;
175 for (i = 0; i < row_width; i++)
176 {
177 png_byte value;
178
179 value = (png_byte)(*sp & 0x0f);
180 v |= (value << shift);
181
182 if (shift == 0)
183 {
184 shift = 4;
185 *dp = (png_byte)v;
186 dp++;
187 v = 0;
188 }
189 else
190 shift -= 4;
191
192 sp++;
193 }
194 if (shift != 4)
195 *dp = (png_byte)v;
196 break;
197 }
198 }
199 row_info->bit_depth = (png_byte)bit_depth;
200 row_info->pixel_depth = (png_byte)(bit_depth * row_info->channels);
201 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
202 row_info->width);
203 }
204 }
205 #endif
206
207 #ifdef PNG_WRITE_SHIFT_SUPPORTED
208 /* Shift pixel values to take advantage of whole range. Pass the
209 * true number of bits in bit_depth. The row should be packed
210 * according to row_info->bit_depth. Thus, if you had a row of
211 * bit depth 4, but the pixels only had values from 0 to 7, you
212 * would pass 3 as bit_depth, and this routine would translate the
213 * data to 0 to 15.
214 */
215 void /* PRIVATE */
216 png_do_shift(png_row_infop row_info, png_bytep row, png_color_8p bit_depth)
217 {
218 png_debug(1, "in png_do_shift");
219
220 if (
221 row_info->color_type != PNG_COLOR_TYPE_PALETTE)
222 {
223 int shift_start[4], shift_dec[4];
224 int channels = 0;
225
226 if (row_info->color_type & PNG_COLOR_MASK_COLOR)
227 {
228 shift_start[channels] = row_info->bit_depth - bit_depth->red;
229 shift_dec[channels] = bit_depth->red;
230 channels++;
231 shift_start[channels] = row_info->bit_depth - bit_depth->green;
232 shift_dec[channels] = bit_depth->green;
233 channels++;
234 shift_start[channels] = row_info->bit_depth - bit_depth->blue;
235 shift_dec[channels] = bit_depth->blue;
236 channels++;
237 }
238 else
239 {
240 shift_start[channels] = row_info->bit_depth - bit_depth->gray;
241 shift_dec[channels] = bit_depth->gray;
242 channels++;
243 }
244 if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
245 {
246 shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
247 shift_dec[channels] = bit_depth->alpha;
248 channels++;
249 }
250
251 /* With low row depths, could only be grayscale, so one channel */
252 if (row_info->bit_depth < 8)
253 {
254 png_bytep bp = row;
255 png_uint_32 i;
256 png_byte mask;
257 png_uint_32 row_bytes = row_info->rowbytes;
258
259 if (bit_depth->gray == 1 && row_info->bit_depth == 2)
260 mask = 0x55;
261 else if (row_info->bit_depth == 4 && bit_depth->gray == 3)
262 mask = 0x11;
263 else
264 mask = 0xff;
265
266 for (i = 0; i < row_bytes; i++, bp++)
267 {
268 png_uint_16 v;
269 int j;
270
271 v = *bp;
272 *bp = 0;
273 for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
274 {
275 if (j > 0)
276 *bp |= (png_byte)((v << j) & 0xff);
277 else
278 *bp |= (png_byte)((v >> (-j)) & mask);
279 }
280 }
281 }
282 else if (row_info->bit_depth == 8)
283 {
284 png_bytep bp = row;
285 png_uint_32 i;
286 png_uint_32 istop = channels * row_info->width;
287
288 for (i = 0; i < istop; i++, bp++)
289 {
290
291 png_uint_16 v;
292 int j;
293 int c = (int)(i%channels);
294
295 v = *bp;
296 *bp = 0;
297 for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
298 {
299 if (j > 0)
300 *bp |= (png_byte)((v << j) & 0xff);
301 else
302 *bp |= (png_byte)((v >> (-j)) & 0xff);
303 }
304 }
305 }
306 else
307 {
308 png_bytep bp;
309 png_uint_32 i;
310 png_uint_32 istop = channels * row_info->width;
311
312 for (bp = row, i = 0; i < istop; i++)
313 {
314 int c = (int)(i%channels);
315 png_uint_16 value, v;
316 int j;
317
318 v = (png_uint_16)(((png_uint_16)(*bp) << 8) + *(bp + 1));
319 value = 0;
320 for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
321 {
322 if (j > 0)
323 value |= (png_uint_16)((v << j) & (png_uint_16)0xffff);
324 else
325 value |= (png_uint_16)((v >> (-j)) & (png_uint_16)0xffff);
326 }
327 *bp++ = (png_byte)(value >> 8);
328 *bp++ = (png_byte)(value & 0xff);
329 }
330 }
331 }
332 }
333 #endif
334
335 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
336 void /* PRIVATE */
337 png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
338 {
339 png_debug(1, "in png_do_write_swap_alpha");
340
341 {
342 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
343 {
344 /* This converts from ARGB to RGBA */
345 if (row_info->bit_depth == 8)
346 {
347 png_bytep sp, dp;
348 png_uint_32 i;
349 png_uint_32 row_width = row_info->width;
350 for (i = 0, sp = dp = row; i < row_width; i++)
351 {
352 png_byte save = *(sp++);
353 *(dp++) = *(sp++);
354 *(dp++) = *(sp++);
355 *(dp++) = *(sp++);
356 *(dp++) = save;
357 }
358 }
359 /* This converts from AARRGGBB to RRGGBBAA */
360 else
361 {
362 png_bytep sp, dp;
363 png_uint_32 i;
364 png_uint_32 row_width = row_info->width;
365
366 for (i = 0, sp = dp = row; i < row_width; i++)
367 {
368 png_byte save[2];
369 save[0] = *(sp++);
370 save[1] = *(sp++);
371 *(dp++) = *(sp++);
372 *(dp++) = *(sp++);
373 *(dp++) = *(sp++);
374 *(dp++) = *(sp++);
375 *(dp++) = *(sp++);
376 *(dp++) = *(sp++);
377 *(dp++) = save[0];
378 *(dp++) = save[1];
379 }
380 }
381 }
382 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
383 {
384 /* This converts from AG to GA */
385 if (row_info->bit_depth == 8)
386 {
387 png_bytep sp, dp;
388 png_uint_32 i;
389 png_uint_32 row_width = row_info->width;
390
391 for (i = 0, sp = dp = row; i < row_width; i++)
392 {
393 png_byte save = *(sp++);
394 *(dp++) = *(sp++);
395 *(dp++) = save;
396 }
397 }
398 /* This converts from AAGG to GGAA */
399 else
400 {
401 png_bytep sp, dp;
402 png_uint_32 i;
403 png_uint_32 row_width = row_info->width;
404
405 for (i = 0, sp = dp = row; i < row_width; i++)
406 {
407 png_byte save[2];
408 save[0] = *(sp++);
409 save[1] = *(sp++);
410 *(dp++) = *(sp++);
411 *(dp++) = *(sp++);
412 *(dp++) = save[0];
413 *(dp++) = save[1];
414 }
415 }
416 }
417 }
418 }
419 #endif
420
421 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
422 void /* PRIVATE */
423 png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
424 {
425 png_debug(1, "in png_do_write_invert_alpha");
426
427 {
428 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
429 {
430 /* This inverts the alpha channel in RGBA */
431 if (row_info->bit_depth == 8)
432 {
433 png_bytep sp, dp;
434 png_uint_32 i;
435 png_uint_32 row_width = row_info->width;
436 for (i = 0, sp = dp = row; i < row_width; i++)
437 {
438 /* Does nothing
439 *(dp++) = *(sp++);
440 *(dp++) = *(sp++);
441 *(dp++) = *(sp++);
442 */
443 sp+=3; dp = sp;
444 *(dp++) = (png_byte)(255 - *(sp++));
445 }
446 }
447 /* This inverts the alpha channel in RRGGBBAA */
448 else
449 {
450 png_bytep sp, dp;
451 png_uint_32 i;
452 png_uint_32 row_width = row_info->width;
453
454 for (i = 0, sp = dp = row; i < row_width; i++)
455 {
456 /* Does nothing
457 *(dp++) = *(sp++);
458 *(dp++) = *(sp++);
459 *(dp++) = *(sp++);
460 *(dp++) = *(sp++);
461 *(dp++) = *(sp++);
462 *(dp++) = *(sp++);
463 */
464 sp+=6; dp = sp;
465 *(dp++) = (png_byte)(255 - *(sp++));
466 *(dp++) = (png_byte)(255 - *(sp++));
467 }
468 }
469 }
470 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
471 {
472 /* This inverts the alpha channel in GA */
473 if (row_info->bit_depth == 8)
474 {
475 png_bytep sp, dp;
476 png_uint_32 i;
477 png_uint_32 row_width = row_info->width;
478
479 for (i = 0, sp = dp = row; i < row_width; i++)
480 {
481 *(dp++) = *(sp++);
482 *(dp++) = (png_byte)(255 - *(sp++));
483 }
484 }
485 /* This inverts the alpha channel in GGAA */
486 else
487 {
488 png_bytep sp, dp;
489 png_uint_32 i;
490 png_uint_32 row_width = row_info->width;
491
492 for (i = 0, sp = dp = row; i < row_width; i++)
493 {
494 /* Does nothing
495 *(dp++) = *(sp++);
496 *(dp++) = *(sp++);
497 */
498 sp+=2; dp = sp;
499 *(dp++) = (png_byte)(255 - *(sp++));
500 *(dp++) = (png_byte)(255 - *(sp++));
501 }
502 }
503 }
504 }
505 }
506 #endif
507
508 #ifdef PNG_MNG_FEATURES_SUPPORTED
509 /* Undoes intrapixel differencing */
510 void /* PRIVATE */
511 png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
512 {
513 png_debug(1, "in png_do_write_intrapixel");
514
515 if (
516 (row_info->color_type & PNG_COLOR_MASK_COLOR))
517 {
518 int bytes_per_pixel;
519 png_uint_32 row_width = row_info->width;
520 if (row_info->bit_depth == 8)
521 {
522 png_bytep rp;
523 png_uint_32 i;
524
525 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
526 bytes_per_pixel = 3;
527 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
528 bytes_per_pixel = 4;
529 else
530 return;
531
532 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
533 {
534 *(rp) = (png_byte)((*rp - *(rp+1))&0xff);
535 *(rp+2) = (png_byte)((*(rp+2) - *(rp+1))&0xff);
536 }
537 }
538 else if (row_info->bit_depth == 16)
539 {
540 png_bytep rp;
541 png_uint_32 i;
542
543 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
544 bytes_per_pixel = 6;
545 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
546 bytes_per_pixel = 8;
547 else
548 return;
549
550 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
551 {
552 png_uint_32 s0 = (*(rp ) << 8) | *(rp+1);
553 png_uint_32 s1 = (*(rp+2) << 8) | *(rp+3);
554 png_uint_32 s2 = (*(rp+4) << 8) | *(rp+5);
555 png_uint_32 red = (png_uint_32)((s0 - s1) & 0xffffL);
556 png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
557 *(rp ) = (png_byte)((red >> 8) & 0xff);
558 *(rp+1) = (png_byte)(red & 0xff);
559 *(rp+4) = (png_byte)((blue >> 8) & 0xff);
560 *(rp+5) = (png_byte)(blue & 0xff);
561 }
562 }
563 }
564 }
565 #endif /* PNG_MNG_FEATURES_SUPPORTED */
566 #endif /* PNG_WRITE_SUPPORTED */
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