f129ef129c03cb6cba43162979732c77e571da5e
[reactos.git] / reactos / dll / 3rdparty / libpng / pngrtran.c
1
2 /* pngrtran.c - transforms the data in a row for PNG readers
3 *
4 * Last changed in libpng 1.6.19 [November 12, 2015]
5 * Copyright (c) 1998-2015 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 * This file contains functions optionally called by an application
14 * in order to tell libpng how to handle data when reading a PNG.
15 * Transformations that are used in both reading and writing are
16 * in pngtrans.c.
17 */
18
19 #include "pngpriv.h"
20
21 #ifdef PNG_READ_SUPPORTED
22
23 /* Set the action on getting a CRC error for an ancillary or critical chunk. */
24 void PNGAPI
25 png_set_crc_action(png_structrp png_ptr, int crit_action, int ancil_action)
26 {
27 png_debug(1, "in png_set_crc_action");
28
29 if (png_ptr == NULL)
30 return;
31
32 /* Tell libpng how we react to CRC errors in critical chunks */
33 switch (crit_action)
34 {
35 case PNG_CRC_NO_CHANGE: /* Leave setting as is */
36 break;
37
38 case PNG_CRC_WARN_USE: /* Warn/use data */
39 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
40 png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE;
41 break;
42
43 case PNG_CRC_QUIET_USE: /* Quiet/use data */
44 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
45 png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE |
46 PNG_FLAG_CRC_CRITICAL_IGNORE;
47 break;
48
49 case PNG_CRC_WARN_DISCARD: /* Not a valid action for critical data */
50 png_warning(png_ptr,
51 "Can't discard critical data on CRC error");
52 case PNG_CRC_ERROR_QUIT: /* Error/quit */
53
54 case PNG_CRC_DEFAULT:
55 default:
56 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
57 break;
58 }
59
60 /* Tell libpng how we react to CRC errors in ancillary chunks */
61 switch (ancil_action)
62 {
63 case PNG_CRC_NO_CHANGE: /* Leave setting as is */
64 break;
65
66 case PNG_CRC_WARN_USE: /* Warn/use data */
67 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
68 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE;
69 break;
70
71 case PNG_CRC_QUIET_USE: /* Quiet/use data */
72 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
73 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE |
74 PNG_FLAG_CRC_ANCILLARY_NOWARN;
75 break;
76
77 case PNG_CRC_ERROR_QUIT: /* Error/quit */
78 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
79 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN;
80 break;
81
82 case PNG_CRC_WARN_DISCARD: /* Warn/discard data */
83
84 case PNG_CRC_DEFAULT:
85 default:
86 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
87 break;
88 }
89 }
90
91 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
92 /* Is it OK to set a transformation now? Only if png_start_read_image or
93 * png_read_update_info have not been called. It is not necessary for the IHDR
94 * to have been read in all cases; the need_IHDR parameter allows for this
95 * check too.
96 */
97 static int
98 png_rtran_ok(png_structrp png_ptr, int need_IHDR)
99 {
100 if (png_ptr != NULL)
101 {
102 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) != 0)
103 png_app_error(png_ptr,
104 "invalid after png_start_read_image or png_read_update_info");
105
106 else if (need_IHDR && (png_ptr->mode & PNG_HAVE_IHDR) == 0)
107 png_app_error(png_ptr, "invalid before the PNG header has been read");
108
109 else
110 {
111 /* Turn on failure to initialize correctly for all transforms. */
112 png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED;
113
114 return 1; /* Ok */
115 }
116 }
117
118 return 0; /* no png_error possible! */
119 }
120 #endif
121
122 #ifdef PNG_READ_BACKGROUND_SUPPORTED
123 /* Handle alpha and tRNS via a background color */
124 void PNGFAPI
125 png_set_background_fixed(png_structrp png_ptr,
126 png_const_color_16p background_color, int background_gamma_code,
127 int need_expand, png_fixed_point background_gamma)
128 {
129 png_debug(1, "in png_set_background_fixed");
130
131 if (png_rtran_ok(png_ptr, 0) == 0 || background_color == NULL)
132 return;
133
134 if (background_gamma_code == PNG_BACKGROUND_GAMMA_UNKNOWN)
135 {
136 png_warning(png_ptr, "Application must supply a known background gamma");
137 return;
138 }
139
140 png_ptr->transformations |= PNG_COMPOSE | PNG_STRIP_ALPHA;
141 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
142 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
143
144 png_ptr->background = *background_color;
145 png_ptr->background_gamma = background_gamma;
146 png_ptr->background_gamma_type = (png_byte)(background_gamma_code);
147 if (need_expand != 0)
148 png_ptr->transformations |= PNG_BACKGROUND_EXPAND;
149 else
150 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
151 }
152
153 # ifdef PNG_FLOATING_POINT_SUPPORTED
154 void PNGAPI
155 png_set_background(png_structrp png_ptr,
156 png_const_color_16p background_color, int background_gamma_code,
157 int need_expand, double background_gamma)
158 {
159 png_set_background_fixed(png_ptr, background_color, background_gamma_code,
160 need_expand, png_fixed(png_ptr, background_gamma, "png_set_background"));
161 }
162 # endif /* FLOATING_POINT */
163 #endif /* READ_BACKGROUND */
164
165 /* Scale 16-bit depth files to 8-bit depth. If both of these are set then the
166 * one that pngrtran does first (scale) happens. This is necessary to allow the
167 * TRANSFORM and API behavior to be somewhat consistent, and it's simpler.
168 */
169 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
170 void PNGAPI
171 png_set_scale_16(png_structrp png_ptr)
172 {
173 png_debug(1, "in png_set_scale_16");
174
175 if (png_rtran_ok(png_ptr, 0) == 0)
176 return;
177
178 png_ptr->transformations |= PNG_SCALE_16_TO_8;
179 }
180 #endif
181
182 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
183 /* Chop 16-bit depth files to 8-bit depth */
184 void PNGAPI
185 png_set_strip_16(png_structrp png_ptr)
186 {
187 png_debug(1, "in png_set_strip_16");
188
189 if (png_rtran_ok(png_ptr, 0) == 0)
190 return;
191
192 png_ptr->transformations |= PNG_16_TO_8;
193 }
194 #endif
195
196 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
197 void PNGAPI
198 png_set_strip_alpha(png_structrp png_ptr)
199 {
200 png_debug(1, "in png_set_strip_alpha");
201
202 if (png_rtran_ok(png_ptr, 0) == 0)
203 return;
204
205 png_ptr->transformations |= PNG_STRIP_ALPHA;
206 }
207 #endif
208
209 #if defined(PNG_READ_ALPHA_MODE_SUPPORTED) || defined(PNG_READ_GAMMA_SUPPORTED)
210 static png_fixed_point
211 translate_gamma_flags(png_structrp png_ptr, png_fixed_point output_gamma,
212 int is_screen)
213 {
214 /* Check for flag values. The main reason for having the old Mac value as a
215 * flag is that it is pretty near impossible to work out what the correct
216 * value is from Apple documentation - a working Mac system is needed to
217 * discover the value!
218 */
219 if (output_gamma == PNG_DEFAULT_sRGB ||
220 output_gamma == PNG_FP_1 / PNG_DEFAULT_sRGB)
221 {
222 /* If there is no sRGB support this just sets the gamma to the standard
223 * sRGB value. (This is a side effect of using this function!)
224 */
225 # ifdef PNG_READ_sRGB_SUPPORTED
226 png_ptr->flags |= PNG_FLAG_ASSUME_sRGB;
227 # else
228 PNG_UNUSED(png_ptr)
229 # endif
230 if (is_screen != 0)
231 output_gamma = PNG_GAMMA_sRGB;
232 else
233 output_gamma = PNG_GAMMA_sRGB_INVERSE;
234 }
235
236 else if (output_gamma == PNG_GAMMA_MAC_18 ||
237 output_gamma == PNG_FP_1 / PNG_GAMMA_MAC_18)
238 {
239 if (is_screen != 0)
240 output_gamma = PNG_GAMMA_MAC_OLD;
241 else
242 output_gamma = PNG_GAMMA_MAC_INVERSE;
243 }
244
245 return output_gamma;
246 }
247
248 # ifdef PNG_FLOATING_POINT_SUPPORTED
249 static png_fixed_point
250 convert_gamma_value(png_structrp png_ptr, double output_gamma)
251 {
252 /* The following silently ignores cases where fixed point (times 100,000)
253 * gamma values are passed to the floating point API. This is safe and it
254 * means the fixed point constants work just fine with the floating point
255 * API. The alternative would just lead to undetected errors and spurious
256 * bug reports. Negative values fail inside the _fixed API unless they
257 * correspond to the flag values.
258 */
259 if (output_gamma > 0 && output_gamma < 128)
260 output_gamma *= PNG_FP_1;
261
262 /* This preserves -1 and -2 exactly: */
263 output_gamma = floor(output_gamma + .5);
264
265 if (output_gamma > PNG_FP_MAX || output_gamma < PNG_FP_MIN)
266 png_fixed_error(png_ptr, "gamma value");
267
268 return (png_fixed_point)output_gamma;
269 }
270 # endif
271 #endif /* READ_ALPHA_MODE || READ_GAMMA */
272
273 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
274 void PNGFAPI
275 png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,
276 png_fixed_point output_gamma)
277 {
278 int compose = 0;
279 png_fixed_point file_gamma;
280
281 png_debug(1, "in png_set_alpha_mode");
282
283 if (png_rtran_ok(png_ptr, 0) == 0)
284 return;
285
286 output_gamma = translate_gamma_flags(png_ptr, output_gamma, 1/*screen*/);
287
288 /* Validate the value to ensure it is in a reasonable range. The value
289 * is expected to be 1 or greater, but this range test allows for some
290 * viewing correction values. The intent is to weed out users of this API
291 * who use the inverse of the gamma value accidentally! Since some of these
292 * values are reasonable this may have to be changed.
293 */
294 if (output_gamma < 70000 || output_gamma > 300000)
295 png_error(png_ptr, "output gamma out of expected range");
296
297 /* The default file gamma is the inverse of the output gamma; the output
298 * gamma may be changed below so get the file value first:
299 */
300 file_gamma = png_reciprocal(output_gamma);
301
302 /* There are really 8 possibilities here, composed of any combination
303 * of:
304 *
305 * premultiply the color channels
306 * do not encode non-opaque pixels
307 * encode the alpha as well as the color channels
308 *
309 * The differences disappear if the input/output ('screen') gamma is 1.0,
310 * because then the encoding is a no-op and there is only the choice of
311 * premultiplying the color channels or not.
312 *
313 * png_set_alpha_mode and png_set_background interact because both use
314 * png_compose to do the work. Calling both is only useful when
315 * png_set_alpha_mode is used to set the default mode - PNG_ALPHA_PNG - along
316 * with a default gamma value. Otherwise PNG_COMPOSE must not be set.
317 */
318 switch (mode)
319 {
320 case PNG_ALPHA_PNG: /* default: png standard */
321 /* No compose, but it may be set by png_set_background! */
322 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
323 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
324 break;
325
326 case PNG_ALPHA_ASSOCIATED: /* color channels premultiplied */
327 compose = 1;
328 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
329 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
330 /* The output is linear: */
331 output_gamma = PNG_FP_1;
332 break;
333
334 case PNG_ALPHA_OPTIMIZED: /* associated, non-opaque pixels linear */
335 compose = 1;
336 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
337 png_ptr->flags |= PNG_FLAG_OPTIMIZE_ALPHA;
338 /* output_gamma records the encoding of opaque pixels! */
339 break;
340
341 case PNG_ALPHA_BROKEN: /* associated, non-linear, alpha encoded */
342 compose = 1;
343 png_ptr->transformations |= PNG_ENCODE_ALPHA;
344 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
345 break;
346
347 default:
348 png_error(png_ptr, "invalid alpha mode");
349 }
350
351 /* Only set the default gamma if the file gamma has not been set (this has
352 * the side effect that the gamma in a second call to png_set_alpha_mode will
353 * be ignored.)
354 */
355 if (png_ptr->colorspace.gamma == 0)
356 {
357 png_ptr->colorspace.gamma = file_gamma;
358 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
359 }
360
361 /* But always set the output gamma: */
362 png_ptr->screen_gamma = output_gamma;
363
364 /* Finally, if pre-multiplying, set the background fields to achieve the
365 * desired result.
366 */
367 if (compose != 0)
368 {
369 /* And obtain alpha pre-multiplication by composing on black: */
370 memset(&png_ptr->background, 0, (sizeof png_ptr->background));
371 png_ptr->background_gamma = png_ptr->colorspace.gamma; /* just in case */
372 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_FILE;
373 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
374
375 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
376 png_error(png_ptr,
377 "conflicting calls to set alpha mode and background");
378
379 png_ptr->transformations |= PNG_COMPOSE;
380 }
381 }
382
383 # ifdef PNG_FLOATING_POINT_SUPPORTED
384 void PNGAPI
385 png_set_alpha_mode(png_structrp png_ptr, int mode, double output_gamma)
386 {
387 png_set_alpha_mode_fixed(png_ptr, mode, convert_gamma_value(png_ptr,
388 output_gamma));
389 }
390 # endif
391 #endif
392
393 #ifdef PNG_READ_QUANTIZE_SUPPORTED
394 /* Dither file to 8-bit. Supply a palette, the current number
395 * of elements in the palette, the maximum number of elements
396 * allowed, and a histogram if possible. If the current number
397 * of colors is greater than the maximum number, the palette will be
398 * modified to fit in the maximum number. "full_quantize" indicates
399 * whether we need a quantizing cube set up for RGB images, or if we
400 * simply are reducing the number of colors in a paletted image.
401 */
402
403 typedef struct png_dsort_struct
404 {
405 struct png_dsort_struct * next;
406 png_byte left;
407 png_byte right;
408 } png_dsort;
409 typedef png_dsort * png_dsortp;
410 typedef png_dsort * * png_dsortpp;
411
412 void PNGAPI
413 png_set_quantize(png_structrp png_ptr, png_colorp palette,
414 int num_palette, int maximum_colors, png_const_uint_16p histogram,
415 int full_quantize)
416 {
417 png_debug(1, "in png_set_quantize");
418
419 if (png_rtran_ok(png_ptr, 0) == 0)
420 return;
421
422 png_ptr->transformations |= PNG_QUANTIZE;
423
424 if (full_quantize == 0)
425 {
426 int i;
427
428 png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr,
429 (png_uint_32)(num_palette * (sizeof (png_byte))));
430 for (i = 0; i < num_palette; i++)
431 png_ptr->quantize_index[i] = (png_byte)i;
432 }
433
434 if (num_palette > maximum_colors)
435 {
436 if (histogram != NULL)
437 {
438 /* This is easy enough, just throw out the least used colors.
439 * Perhaps not the best solution, but good enough.
440 */
441
442 int i;
443
444 /* Initialize an array to sort colors */
445 png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr,
446 (png_uint_32)(num_palette * (sizeof (png_byte))));
447
448 /* Initialize the quantize_sort array */
449 for (i = 0; i < num_palette; i++)
450 png_ptr->quantize_sort[i] = (png_byte)i;
451
452 /* Find the least used palette entries by starting a
453 * bubble sort, and running it until we have sorted
454 * out enough colors. Note that we don't care about
455 * sorting all the colors, just finding which are
456 * least used.
457 */
458
459 for (i = num_palette - 1; i >= maximum_colors; i--)
460 {
461 int done; /* To stop early if the list is pre-sorted */
462 int j;
463
464 done = 1;
465 for (j = 0; j < i; j++)
466 {
467 if (histogram[png_ptr->quantize_sort[j]]
468 < histogram[png_ptr->quantize_sort[j + 1]])
469 {
470 png_byte t;
471
472 t = png_ptr->quantize_sort[j];
473 png_ptr->quantize_sort[j] = png_ptr->quantize_sort[j + 1];
474 png_ptr->quantize_sort[j + 1] = t;
475 done = 0;
476 }
477 }
478
479 if (done != 0)
480 break;
481 }
482
483 /* Swap the palette around, and set up a table, if necessary */
484 if (full_quantize != 0)
485 {
486 int j = num_palette;
487
488 /* Put all the useful colors within the max, but don't
489 * move the others.
490 */
491 for (i = 0; i < maximum_colors; i++)
492 {
493 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
494 {
495 do
496 j--;
497 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
498
499 palette[i] = palette[j];
500 }
501 }
502 }
503 else
504 {
505 int j = num_palette;
506
507 /* Move all the used colors inside the max limit, and
508 * develop a translation table.
509 */
510 for (i = 0; i < maximum_colors; i++)
511 {
512 /* Only move the colors we need to */
513 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
514 {
515 png_color tmp_color;
516
517 do
518 j--;
519 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
520
521 tmp_color = palette[j];
522 palette[j] = palette[i];
523 palette[i] = tmp_color;
524 /* Indicate where the color went */
525 png_ptr->quantize_index[j] = (png_byte)i;
526 png_ptr->quantize_index[i] = (png_byte)j;
527 }
528 }
529
530 /* Find closest color for those colors we are not using */
531 for (i = 0; i < num_palette; i++)
532 {
533 if ((int)png_ptr->quantize_index[i] >= maximum_colors)
534 {
535 int min_d, k, min_k, d_index;
536
537 /* Find the closest color to one we threw out */
538 d_index = png_ptr->quantize_index[i];
539 min_d = PNG_COLOR_DIST(palette[d_index], palette[0]);
540 for (k = 1, min_k = 0; k < maximum_colors; k++)
541 {
542 int d;
543
544 d = PNG_COLOR_DIST(palette[d_index], palette[k]);
545
546 if (d < min_d)
547 {
548 min_d = d;
549 min_k = k;
550 }
551 }
552 /* Point to closest color */
553 png_ptr->quantize_index[i] = (png_byte)min_k;
554 }
555 }
556 }
557 png_free(png_ptr, png_ptr->quantize_sort);
558 png_ptr->quantize_sort = NULL;
559 }
560 else
561 {
562 /* This is much harder to do simply (and quickly). Perhaps
563 * we need to go through a median cut routine, but those
564 * don't always behave themselves with only a few colors
565 * as input. So we will just find the closest two colors,
566 * and throw out one of them (chosen somewhat randomly).
567 * [We don't understand this at all, so if someone wants to
568 * work on improving it, be our guest - AED, GRP]
569 */
570 int i;
571 int max_d;
572 int num_new_palette;
573 png_dsortp t;
574 png_dsortpp hash;
575
576 t = NULL;
577
578 /* Initialize palette index arrays */
579 png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr,
580 (png_uint_32)(num_palette * (sizeof (png_byte))));
581 png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr,
582 (png_uint_32)(num_palette * (sizeof (png_byte))));
583
584 /* Initialize the sort array */
585 for (i = 0; i < num_palette; i++)
586 {
587 png_ptr->index_to_palette[i] = (png_byte)i;
588 png_ptr->palette_to_index[i] = (png_byte)i;
589 }
590
591 hash = (png_dsortpp)png_calloc(png_ptr, (png_uint_32)(769 *
592 (sizeof (png_dsortp))));
593
594 num_new_palette = num_palette;
595
596 /* Initial wild guess at how far apart the farthest pixel
597 * pair we will be eliminating will be. Larger
598 * numbers mean more areas will be allocated, Smaller
599 * numbers run the risk of not saving enough data, and
600 * having to do this all over again.
601 *
602 * I have not done extensive checking on this number.
603 */
604 max_d = 96;
605
606 while (num_new_palette > maximum_colors)
607 {
608 for (i = 0; i < num_new_palette - 1; i++)
609 {
610 int j;
611
612 for (j = i + 1; j < num_new_palette; j++)
613 {
614 int d;
615
616 d = PNG_COLOR_DIST(palette[i], palette[j]);
617
618 if (d <= max_d)
619 {
620
621 t = (png_dsortp)png_malloc_warn(png_ptr,
622 (png_uint_32)(sizeof (png_dsort)));
623
624 if (t == NULL)
625 break;
626
627 t->next = hash[d];
628 t->left = (png_byte)i;
629 t->right = (png_byte)j;
630 hash[d] = t;
631 }
632 }
633 if (t == NULL)
634 break;
635 }
636
637 if (t != NULL)
638 for (i = 0; i <= max_d; i++)
639 {
640 if (hash[i] != NULL)
641 {
642 png_dsortp p;
643
644 for (p = hash[i]; p; p = p->next)
645 {
646 if ((int)png_ptr->index_to_palette[p->left]
647 < num_new_palette &&
648 (int)png_ptr->index_to_palette[p->right]
649 < num_new_palette)
650 {
651 int j, next_j;
652
653 if (num_new_palette & 0x01)
654 {
655 j = p->left;
656 next_j = p->right;
657 }
658 else
659 {
660 j = p->right;
661 next_j = p->left;
662 }
663
664 num_new_palette--;
665 palette[png_ptr->index_to_palette[j]]
666 = palette[num_new_palette];
667 if (full_quantize == 0)
668 {
669 int k;
670
671 for (k = 0; k < num_palette; k++)
672 {
673 if (png_ptr->quantize_index[k] ==
674 png_ptr->index_to_palette[j])
675 png_ptr->quantize_index[k] =
676 png_ptr->index_to_palette[next_j];
677
678 if ((int)png_ptr->quantize_index[k] ==
679 num_new_palette)
680 png_ptr->quantize_index[k] =
681 png_ptr->index_to_palette[j];
682 }
683 }
684
685 png_ptr->index_to_palette[png_ptr->palette_to_index
686 [num_new_palette]] = png_ptr->index_to_palette[j];
687
688 png_ptr->palette_to_index[png_ptr->index_to_palette[j]]
689 = png_ptr->palette_to_index[num_new_palette];
690
691 png_ptr->index_to_palette[j] =
692 (png_byte)num_new_palette;
693
694 png_ptr->palette_to_index[num_new_palette] =
695 (png_byte)j;
696 }
697 if (num_new_palette <= maximum_colors)
698 break;
699 }
700 if (num_new_palette <= maximum_colors)
701 break;
702 }
703 }
704
705 for (i = 0; i < 769; i++)
706 {
707 if (hash[i] != NULL)
708 {
709 png_dsortp p = hash[i];
710 while (p)
711 {
712 t = p->next;
713 png_free(png_ptr, p);
714 p = t;
715 }
716 }
717 hash[i] = 0;
718 }
719 max_d += 96;
720 }
721 png_free(png_ptr, hash);
722 png_free(png_ptr, png_ptr->palette_to_index);
723 png_free(png_ptr, png_ptr->index_to_palette);
724 png_ptr->palette_to_index = NULL;
725 png_ptr->index_to_palette = NULL;
726 }
727 num_palette = maximum_colors;
728 }
729 if (png_ptr->palette == NULL)
730 {
731 png_ptr->palette = palette;
732 }
733 png_ptr->num_palette = (png_uint_16)num_palette;
734
735 if (full_quantize != 0)
736 {
737 int i;
738 png_bytep distance;
739 int total_bits = PNG_QUANTIZE_RED_BITS + PNG_QUANTIZE_GREEN_BITS +
740 PNG_QUANTIZE_BLUE_BITS;
741 int num_red = (1 << PNG_QUANTIZE_RED_BITS);
742 int num_green = (1 << PNG_QUANTIZE_GREEN_BITS);
743 int num_blue = (1 << PNG_QUANTIZE_BLUE_BITS);
744 png_size_t num_entries = ((png_size_t)1 << total_bits);
745
746 png_ptr->palette_lookup = (png_bytep)png_calloc(png_ptr,
747 (png_uint_32)(num_entries * (sizeof (png_byte))));
748
749 distance = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_entries *
750 (sizeof (png_byte))));
751
752 memset(distance, 0xff, num_entries * (sizeof (png_byte)));
753
754 for (i = 0; i < num_palette; i++)
755 {
756 int ir, ig, ib;
757 int r = (palette[i].red >> (8 - PNG_QUANTIZE_RED_BITS));
758 int g = (palette[i].green >> (8 - PNG_QUANTIZE_GREEN_BITS));
759 int b = (palette[i].blue >> (8 - PNG_QUANTIZE_BLUE_BITS));
760
761 for (ir = 0; ir < num_red; ir++)
762 {
763 /* int dr = abs(ir - r); */
764 int dr = ((ir > r) ? ir - r : r - ir);
765 int index_r = (ir << (PNG_QUANTIZE_BLUE_BITS +
766 PNG_QUANTIZE_GREEN_BITS));
767
768 for (ig = 0; ig < num_green; ig++)
769 {
770 /* int dg = abs(ig - g); */
771 int dg = ((ig > g) ? ig - g : g - ig);
772 int dt = dr + dg;
773 int dm = ((dr > dg) ? dr : dg);
774 int index_g = index_r | (ig << PNG_QUANTIZE_BLUE_BITS);
775
776 for (ib = 0; ib < num_blue; ib++)
777 {
778 int d_index = index_g | ib;
779 /* int db = abs(ib - b); */
780 int db = ((ib > b) ? ib - b : b - ib);
781 int dmax = ((dm > db) ? dm : db);
782 int d = dmax + dt + db;
783
784 if (d < (int)distance[d_index])
785 {
786 distance[d_index] = (png_byte)d;
787 png_ptr->palette_lookup[d_index] = (png_byte)i;
788 }
789 }
790 }
791 }
792 }
793
794 png_free(png_ptr, distance);
795 }
796 }
797 #endif /* READ_QUANTIZE */
798
799 #ifdef PNG_READ_GAMMA_SUPPORTED
800 void PNGFAPI
801 png_set_gamma_fixed(png_structrp png_ptr, png_fixed_point scrn_gamma,
802 png_fixed_point file_gamma)
803 {
804 png_debug(1, "in png_set_gamma_fixed");
805
806 if (png_rtran_ok(png_ptr, 0) == 0)
807 return;
808
809 /* New in libpng-1.5.4 - reserve particular negative values as flags. */
810 scrn_gamma = translate_gamma_flags(png_ptr, scrn_gamma, 1/*screen*/);
811 file_gamma = translate_gamma_flags(png_ptr, file_gamma, 0/*file*/);
812
813 /* Checking the gamma values for being >0 was added in 1.5.4 along with the
814 * premultiplied alpha support; this actually hides an undocumented feature
815 * of the previous implementation which allowed gamma processing to be
816 * disabled in background handling. There is no evidence (so far) that this
817 * was being used; however, png_set_background itself accepted and must still
818 * accept '0' for the gamma value it takes, because it isn't always used.
819 *
820 * Since this is an API change (albeit a very minor one that removes an
821 * undocumented API feature) the following checks were only enabled in
822 * libpng-1.6.0.
823 */
824 if (file_gamma <= 0)
825 png_error(png_ptr, "invalid file gamma in png_set_gamma");
826
827 if (scrn_gamma <= 0)
828 png_error(png_ptr, "invalid screen gamma in png_set_gamma");
829
830 /* Set the gamma values unconditionally - this overrides the value in the PNG
831 * file if a gAMA chunk was present. png_set_alpha_mode provides a
832 * different, easier, way to default the file gamma.
833 */
834 png_ptr->colorspace.gamma = file_gamma;
835 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
836 png_ptr->screen_gamma = scrn_gamma;
837 }
838
839 # ifdef PNG_FLOATING_POINT_SUPPORTED
840 void PNGAPI
841 png_set_gamma(png_structrp png_ptr, double scrn_gamma, double file_gamma)
842 {
843 png_set_gamma_fixed(png_ptr, convert_gamma_value(png_ptr, scrn_gamma),
844 convert_gamma_value(png_ptr, file_gamma));
845 }
846 # endif /* FLOATING_POINT */
847 #endif /* READ_GAMMA */
848
849 #ifdef PNG_READ_EXPAND_SUPPORTED
850 /* Expand paletted images to RGB, expand grayscale images of
851 * less than 8-bit depth to 8-bit depth, and expand tRNS chunks
852 * to alpha channels.
853 */
854 void PNGAPI
855 png_set_expand(png_structrp png_ptr)
856 {
857 png_debug(1, "in png_set_expand");
858
859 if (png_rtran_ok(png_ptr, 0) == 0)
860 return;
861
862 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
863 }
864
865 /* GRR 19990627: the following three functions currently are identical
866 * to png_set_expand(). However, it is entirely reasonable that someone
867 * might wish to expand an indexed image to RGB but *not* expand a single,
868 * fully transparent palette entry to a full alpha channel--perhaps instead
869 * convert tRNS to the grayscale/RGB format (16-bit RGB value), or replace
870 * the transparent color with a particular RGB value, or drop tRNS entirely.
871 * IOW, a future version of the library may make the transformations flag
872 * a bit more fine-grained, with separate bits for each of these three
873 * functions.
874 *
875 * More to the point, these functions make it obvious what libpng will be
876 * doing, whereas "expand" can (and does) mean any number of things.
877 *
878 * GRP 20060307: In libpng-1.2.9, png_set_gray_1_2_4_to_8() was modified
879 * to expand only the sample depth but not to expand the tRNS to alpha
880 * and its name was changed to png_set_expand_gray_1_2_4_to_8().
881 */
882
883 /* Expand paletted images to RGB. */
884 void PNGAPI
885 png_set_palette_to_rgb(png_structrp png_ptr)
886 {
887 png_debug(1, "in png_set_palette_to_rgb");
888
889 if (png_rtran_ok(png_ptr, 0) == 0)
890 return;
891
892 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
893 }
894
895 /* Expand grayscale images of less than 8-bit depth to 8 bits. */
896 void PNGAPI
897 png_set_expand_gray_1_2_4_to_8(png_structrp png_ptr)
898 {
899 png_debug(1, "in png_set_expand_gray_1_2_4_to_8");
900
901 if (png_rtran_ok(png_ptr, 0) == 0)
902 return;
903
904 png_ptr->transformations |= PNG_EXPAND;
905 }
906
907 /* Expand tRNS chunks to alpha channels. */
908 void PNGAPI
909 png_set_tRNS_to_alpha(png_structrp png_ptr)
910 {
911 png_debug(1, "in png_set_tRNS_to_alpha");
912
913 if (png_rtran_ok(png_ptr, 0) == 0)
914 return;
915
916 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
917 }
918 #endif /* READ_EXPAND */
919
920 #ifdef PNG_READ_EXPAND_16_SUPPORTED
921 /* Expand to 16-bit channels, expand the tRNS chunk too (because otherwise
922 * it may not work correctly.)
923 */
924 void PNGAPI
925 png_set_expand_16(png_structrp png_ptr)
926 {
927 png_debug(1, "in png_set_expand_16");
928
929 if (png_rtran_ok(png_ptr, 0) == 0)
930 return;
931
932 png_ptr->transformations |= (PNG_EXPAND_16 | PNG_EXPAND | PNG_EXPAND_tRNS);
933 }
934 #endif
935
936 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
937 void PNGAPI
938 png_set_gray_to_rgb(png_structrp png_ptr)
939 {
940 png_debug(1, "in png_set_gray_to_rgb");
941
942 if (png_rtran_ok(png_ptr, 0) == 0)
943 return;
944
945 /* Because rgb must be 8 bits or more: */
946 png_set_expand_gray_1_2_4_to_8(png_ptr);
947 png_ptr->transformations |= PNG_GRAY_TO_RGB;
948 }
949 #endif
950
951 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
952 void PNGFAPI
953 png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action,
954 png_fixed_point red, png_fixed_point green)
955 {
956 png_debug(1, "in png_set_rgb_to_gray");
957
958 /* Need the IHDR here because of the check on color_type below. */
959 /* TODO: fix this */
960 if (png_rtran_ok(png_ptr, 1) == 0)
961 return;
962
963 switch (error_action)
964 {
965 case PNG_ERROR_ACTION_NONE:
966 png_ptr->transformations |= PNG_RGB_TO_GRAY;
967 break;
968
969 case PNG_ERROR_ACTION_WARN:
970 png_ptr->transformations |= PNG_RGB_TO_GRAY_WARN;
971 break;
972
973 case PNG_ERROR_ACTION_ERROR:
974 png_ptr->transformations |= PNG_RGB_TO_GRAY_ERR;
975 break;
976
977 default:
978 png_error(png_ptr, "invalid error action to rgb_to_gray");
979 }
980
981 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
982 #ifdef PNG_READ_EXPAND_SUPPORTED
983 png_ptr->transformations |= PNG_EXPAND;
984 #else
985 {
986 /* Make this an error in 1.6 because otherwise the application may assume
987 * that it just worked and get a memory overwrite.
988 */
989 png_error(png_ptr,
990 "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED");
991
992 /* png_ptr->transformations &= ~PNG_RGB_TO_GRAY; */
993 }
994 #endif
995 {
996 if (red >= 0 && green >= 0 && red + green <= PNG_FP_1)
997 {
998 png_uint_16 red_int, green_int;
999
1000 /* NOTE: this calculation does not round, but this behavior is retained
1001 * for consistency; the inaccuracy is very small. The code here always
1002 * overwrites the coefficients, regardless of whether they have been
1003 * defaulted or set already.
1004 */
1005 red_int = (png_uint_16)(((png_uint_32)red*32768)/100000);
1006 green_int = (png_uint_16)(((png_uint_32)green*32768)/100000);
1007
1008 png_ptr->rgb_to_gray_red_coeff = red_int;
1009 png_ptr->rgb_to_gray_green_coeff = green_int;
1010 png_ptr->rgb_to_gray_coefficients_set = 1;
1011 }
1012
1013 else
1014 {
1015 if (red >= 0 && green >= 0)
1016 png_app_warning(png_ptr,
1017 "ignoring out of range rgb_to_gray coefficients");
1018
1019 /* Use the defaults, from the cHRM chunk if set, else the historical
1020 * values which are close to the sRGB/HDTV/ITU-Rec 709 values. See
1021 * png_do_rgb_to_gray for more discussion of the values. In this case
1022 * the coefficients are not marked as 'set' and are not overwritten if
1023 * something has already provided a default.
1024 */
1025 if (png_ptr->rgb_to_gray_red_coeff == 0 &&
1026 png_ptr->rgb_to_gray_green_coeff == 0)
1027 {
1028 png_ptr->rgb_to_gray_red_coeff = 6968;
1029 png_ptr->rgb_to_gray_green_coeff = 23434;
1030 /* png_ptr->rgb_to_gray_blue_coeff = 2366; */
1031 }
1032 }
1033 }
1034 }
1035
1036 #ifdef PNG_FLOATING_POINT_SUPPORTED
1037 /* Convert a RGB image to a grayscale of the same width. This allows us,
1038 * for example, to convert a 24 bpp RGB image into an 8 bpp grayscale image.
1039 */
1040
1041 void PNGAPI
1042 png_set_rgb_to_gray(png_structrp png_ptr, int error_action, double red,
1043 double green)
1044 {
1045 png_set_rgb_to_gray_fixed(png_ptr, error_action,
1046 png_fixed(png_ptr, red, "rgb to gray red coefficient"),
1047 png_fixed(png_ptr, green, "rgb to gray green coefficient"));
1048 }
1049 #endif /* FLOATING POINT */
1050
1051 #endif /* RGB_TO_GRAY */
1052
1053 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
1054 defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
1055 void PNGAPI
1056 png_set_read_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr
1057 read_user_transform_fn)
1058 {
1059 png_debug(1, "in png_set_read_user_transform_fn");
1060
1061 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
1062 png_ptr->transformations |= PNG_USER_TRANSFORM;
1063 png_ptr->read_user_transform_fn = read_user_transform_fn;
1064 #endif
1065 }
1066 #endif
1067
1068 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
1069 #ifdef PNG_READ_GAMMA_SUPPORTED
1070 /* In the case of gamma transformations only do transformations on images where
1071 * the [file] gamma and screen_gamma are not close reciprocals, otherwise it
1072 * slows things down slightly, and also needlessly introduces small errors.
1073 */
1074 static int /* PRIVATE */
1075 png_gamma_threshold(png_fixed_point screen_gamma, png_fixed_point file_gamma)
1076 {
1077 /* PNG_GAMMA_THRESHOLD is the threshold for performing gamma
1078 * correction as a difference of the overall transform from 1.0
1079 *
1080 * We want to compare the threshold with s*f - 1, if we get
1081 * overflow here it is because of wacky gamma values so we
1082 * turn on processing anyway.
1083 */
1084 png_fixed_point gtest;
1085 return !png_muldiv(&gtest, screen_gamma, file_gamma, PNG_FP_1) ||
1086 png_gamma_significant(gtest);
1087 }
1088 #endif
1089
1090 /* Initialize everything needed for the read. This includes modifying
1091 * the palette.
1092 */
1093
1094 /* For the moment 'png_init_palette_transformations' and
1095 * 'png_init_rgb_transformations' only do some flag canceling optimizations.
1096 * The intent is that these two routines should have palette or rgb operations
1097 * extracted from 'png_init_read_transformations'.
1098 */
1099 static void /* PRIVATE */
1100 png_init_palette_transformations(png_structrp png_ptr)
1101 {
1102 /* Called to handle the (input) palette case. In png_do_read_transformations
1103 * the first step is to expand the palette if requested, so this code must
1104 * take care to only make changes that are invariant with respect to the
1105 * palette expansion, or only do them if there is no expansion.
1106 *
1107 * STRIP_ALPHA has already been handled in the caller (by setting num_trans
1108 * to 0.)
1109 */
1110 int input_has_alpha = 0;
1111 int input_has_transparency = 0;
1112
1113 if (png_ptr->num_trans > 0)
1114 {
1115 int i;
1116
1117 /* Ignore if all the entries are opaque (unlikely!) */
1118 for (i=0; i<png_ptr->num_trans; ++i)
1119 {
1120 if (png_ptr->trans_alpha[i] == 255)
1121 continue;
1122 else if (png_ptr->trans_alpha[i] == 0)
1123 input_has_transparency = 1;
1124 else
1125 {
1126 input_has_transparency = 1;
1127 input_has_alpha = 1;
1128 break;
1129 }
1130 }
1131 }
1132
1133 /* If no alpha we can optimize. */
1134 if (input_has_alpha == 0)
1135 {
1136 /* Any alpha means background and associative alpha processing is
1137 * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
1138 * and ENCODE_ALPHA are irrelevant.
1139 */
1140 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1141 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1142
1143 if (input_has_transparency == 0)
1144 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1145 }
1146
1147 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1148 /* png_set_background handling - deals with the complexity of whether the
1149 * background color is in the file format or the screen format in the case
1150 * where an 'expand' will happen.
1151 */
1152
1153 /* The following code cannot be entered in the alpha pre-multiplication case
1154 * because PNG_BACKGROUND_EXPAND is cancelled below.
1155 */
1156 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
1157 (png_ptr->transformations & PNG_EXPAND) != 0)
1158 {
1159 {
1160 png_ptr->background.red =
1161 png_ptr->palette[png_ptr->background.index].red;
1162 png_ptr->background.green =
1163 png_ptr->palette[png_ptr->background.index].green;
1164 png_ptr->background.blue =
1165 png_ptr->palette[png_ptr->background.index].blue;
1166
1167 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1168 if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
1169 {
1170 if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
1171 {
1172 /* Invert the alpha channel (in tRNS) unless the pixels are
1173 * going to be expanded, in which case leave it for later
1174 */
1175 int i, istop = png_ptr->num_trans;
1176
1177 for (i=0; i<istop; i++)
1178 png_ptr->trans_alpha[i] = (png_byte)(255 -
1179 png_ptr->trans_alpha[i]);
1180 }
1181 }
1182 #endif /* READ_INVERT_ALPHA */
1183 }
1184 } /* background expand and (therefore) no alpha association. */
1185 #endif /* READ_EXPAND && READ_BACKGROUND */
1186 }
1187
1188 static void /* PRIVATE */
1189 png_init_rgb_transformations(png_structrp png_ptr)
1190 {
1191 /* Added to libpng-1.5.4: check the color type to determine whether there
1192 * is any alpha or transparency in the image and simply cancel the
1193 * background and alpha mode stuff if there isn't.
1194 */
1195 int input_has_alpha = (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0;
1196 int input_has_transparency = png_ptr->num_trans > 0;
1197
1198 /* If no alpha we can optimize. */
1199 if (input_has_alpha == 0)
1200 {
1201 /* Any alpha means background and associative alpha processing is
1202 * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
1203 * and ENCODE_ALPHA are irrelevant.
1204 */
1205 # ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1206 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1207 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1208 # endif
1209
1210 if (input_has_transparency == 0)
1211 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1212 }
1213
1214 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1215 /* png_set_background handling - deals with the complexity of whether the
1216 * background color is in the file format or the screen format in the case
1217 * where an 'expand' will happen.
1218 */
1219
1220 /* The following code cannot be entered in the alpha pre-multiplication case
1221 * because PNG_BACKGROUND_EXPAND is cancelled below.
1222 */
1223 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
1224 (png_ptr->transformations & PNG_EXPAND) != 0 &&
1225 (png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
1226 /* i.e., GRAY or GRAY_ALPHA */
1227 {
1228 {
1229 /* Expand background and tRNS chunks */
1230 int gray = png_ptr->background.gray;
1231 int trans_gray = png_ptr->trans_color.gray;
1232
1233 switch (png_ptr->bit_depth)
1234 {
1235 case 1:
1236 gray *= 0xff;
1237 trans_gray *= 0xff;
1238 break;
1239
1240 case 2:
1241 gray *= 0x55;
1242 trans_gray *= 0x55;
1243 break;
1244
1245 case 4:
1246 gray *= 0x11;
1247 trans_gray *= 0x11;
1248 break;
1249
1250 default:
1251
1252 case 8:
1253 /* FALL THROUGH (Already 8 bits) */
1254
1255 case 16:
1256 /* Already a full 16 bits */
1257 break;
1258 }
1259
1260 png_ptr->background.red = png_ptr->background.green =
1261 png_ptr->background.blue = (png_uint_16)gray;
1262
1263 if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
1264 {
1265 png_ptr->trans_color.red = png_ptr->trans_color.green =
1266 png_ptr->trans_color.blue = (png_uint_16)trans_gray;
1267 }
1268 }
1269 } /* background expand and (therefore) no alpha association. */
1270 #endif /* READ_EXPAND && READ_BACKGROUND */
1271 }
1272
1273 void /* PRIVATE */
1274 png_init_read_transformations(png_structrp png_ptr)
1275 {
1276 png_debug(1, "in png_init_read_transformations");
1277
1278 /* This internal function is called from png_read_start_row in pngrutil.c
1279 * and it is called before the 'rowbytes' calculation is done, so the code
1280 * in here can change or update the transformations flags.
1281 *
1282 * First do updates that do not depend on the details of the PNG image data
1283 * being processed.
1284 */
1285
1286 #ifdef PNG_READ_GAMMA_SUPPORTED
1287 /* Prior to 1.5.4 these tests were performed from png_set_gamma, 1.5.4 adds
1288 * png_set_alpha_mode and this is another source for a default file gamma so
1289 * the test needs to be performed later - here. In addition prior to 1.5.4
1290 * the tests were repeated for the PALETTE color type here - this is no
1291 * longer necessary (and doesn't seem to have been necessary before.)
1292 */
1293 {
1294 /* The following temporary indicates if overall gamma correction is
1295 * required.
1296 */
1297 int gamma_correction = 0;
1298
1299 if (png_ptr->colorspace.gamma != 0) /* has been set */
1300 {
1301 if (png_ptr->screen_gamma != 0) /* screen set too */
1302 gamma_correction = png_gamma_threshold(png_ptr->colorspace.gamma,
1303 png_ptr->screen_gamma);
1304
1305 else
1306 /* Assume the output matches the input; a long time default behavior
1307 * of libpng, although the standard has nothing to say about this.
1308 */
1309 png_ptr->screen_gamma = png_reciprocal(png_ptr->colorspace.gamma);
1310 }
1311
1312 else if (png_ptr->screen_gamma != 0)
1313 /* The converse - assume the file matches the screen, note that this
1314 * perhaps undesireable default can (from 1.5.4) be changed by calling
1315 * png_set_alpha_mode (even if the alpha handling mode isn't required
1316 * or isn't changed from the default.)
1317 */
1318 png_ptr->colorspace.gamma = png_reciprocal(png_ptr->screen_gamma);
1319
1320 else /* neither are set */
1321 /* Just in case the following prevents any processing - file and screen
1322 * are both assumed to be linear and there is no way to introduce a
1323 * third gamma value other than png_set_background with 'UNIQUE', and,
1324 * prior to 1.5.4
1325 */
1326 png_ptr->screen_gamma = png_ptr->colorspace.gamma = PNG_FP_1;
1327
1328 /* We have a gamma value now. */
1329 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
1330
1331 /* Now turn the gamma transformation on or off as appropriate. Notice
1332 * that PNG_GAMMA just refers to the file->screen correction. Alpha
1333 * composition may independently cause gamma correction because it needs
1334 * linear data (e.g. if the file has a gAMA chunk but the screen gamma
1335 * hasn't been specified.) In any case this flag may get turned off in
1336 * the code immediately below if the transform can be handled outside the
1337 * row loop.
1338 */
1339 if (gamma_correction != 0)
1340 png_ptr->transformations |= PNG_GAMMA;
1341
1342 else
1343 png_ptr->transformations &= ~PNG_GAMMA;
1344 }
1345 #endif
1346
1347 /* Certain transformations have the effect of preventing other
1348 * transformations that happen afterward in png_do_read_transformations;
1349 * resolve the interdependencies here. From the code of
1350 * png_do_read_transformations the order is:
1351 *
1352 * 1) PNG_EXPAND (including PNG_EXPAND_tRNS)
1353 * 2) PNG_STRIP_ALPHA (if no compose)
1354 * 3) PNG_RGB_TO_GRAY
1355 * 4) PNG_GRAY_TO_RGB iff !PNG_BACKGROUND_IS_GRAY
1356 * 5) PNG_COMPOSE
1357 * 6) PNG_GAMMA
1358 * 7) PNG_STRIP_ALPHA (if compose)
1359 * 8) PNG_ENCODE_ALPHA
1360 * 9) PNG_SCALE_16_TO_8
1361 * 10) PNG_16_TO_8
1362 * 11) PNG_QUANTIZE (converts to palette)
1363 * 12) PNG_EXPAND_16
1364 * 13) PNG_GRAY_TO_RGB iff PNG_BACKGROUND_IS_GRAY
1365 * 14) PNG_INVERT_MONO
1366 * 15) PNG_INVERT_ALPHA
1367 * 16) PNG_SHIFT
1368 * 17) PNG_PACK
1369 * 18) PNG_BGR
1370 * 19) PNG_PACKSWAP
1371 * 20) PNG_FILLER (includes PNG_ADD_ALPHA)
1372 * 21) PNG_SWAP_ALPHA
1373 * 22) PNG_SWAP_BYTES
1374 * 23) PNG_USER_TRANSFORM [must be last]
1375 */
1376 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1377 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
1378 (png_ptr->transformations & PNG_COMPOSE) == 0)
1379 {
1380 /* Stripping the alpha channel happens immediately after the 'expand'
1381 * transformations, before all other transformation, so it cancels out
1382 * the alpha handling. It has the side effect negating the effect of
1383 * PNG_EXPAND_tRNS too:
1384 */
1385 png_ptr->transformations &= ~(PNG_BACKGROUND_EXPAND | PNG_ENCODE_ALPHA |
1386 PNG_EXPAND_tRNS);
1387 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1388
1389 /* Kill the tRNS chunk itself too. Prior to 1.5.4 this did not happen
1390 * so transparency information would remain just so long as it wasn't
1391 * expanded. This produces unexpected API changes if the set of things
1392 * that do PNG_EXPAND_tRNS changes (perfectly possible given the
1393 * documentation - which says ask for what you want, accept what you
1394 * get.) This makes the behavior consistent from 1.5.4:
1395 */
1396 png_ptr->num_trans = 0;
1397 }
1398 #endif /* STRIP_ALPHA supported, no COMPOSE */
1399
1400 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1401 /* If the screen gamma is about 1.0 then the OPTIMIZE_ALPHA and ENCODE_ALPHA
1402 * settings will have no effect.
1403 */
1404 if (png_gamma_significant(png_ptr->screen_gamma) == 0)
1405 {
1406 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1407 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1408 }
1409 #endif
1410
1411 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1412 /* Make sure the coefficients for the rgb to gray conversion are set
1413 * appropriately.
1414 */
1415 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
1416 png_colorspace_set_rgb_coefficients(png_ptr);
1417 #endif
1418
1419 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1420 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1421 /* Detect gray background and attempt to enable optimization for
1422 * gray --> RGB case.
1423 *
1424 * Note: if PNG_BACKGROUND_EXPAND is set and color_type is either RGB or
1425 * RGB_ALPHA (in which case need_expand is superfluous anyway), the
1426 * background color might actually be gray yet not be flagged as such.
1427 * This is not a problem for the current code, which uses
1428 * PNG_BACKGROUND_IS_GRAY only to decide when to do the
1429 * png_do_gray_to_rgb() transformation.
1430 *
1431 * TODO: this code needs to be revised to avoid the complexity and
1432 * interdependencies. The color type of the background should be recorded in
1433 * png_set_background, along with the bit depth, then the code has a record
1434 * of exactly what color space the background is currently in.
1435 */
1436 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0)
1437 {
1438 /* PNG_BACKGROUND_EXPAND: the background is in the file color space, so if
1439 * the file was grayscale the background value is gray.
1440 */
1441 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
1442 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1443 }
1444
1445 else if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1446 {
1447 /* PNG_COMPOSE: png_set_background was called with need_expand false,
1448 * so the color is in the color space of the output or png_set_alpha_mode
1449 * was called and the color is black. Ignore RGB_TO_GRAY because that
1450 * happens before GRAY_TO_RGB.
1451 */
1452 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
1453 {
1454 if (png_ptr->background.red == png_ptr->background.green &&
1455 png_ptr->background.red == png_ptr->background.blue)
1456 {
1457 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1458 png_ptr->background.gray = png_ptr->background.red;
1459 }
1460 }
1461 }
1462 #endif /* READ_EXPAND && READ_BACKGROUND */
1463 #endif /* READ_GRAY_TO_RGB */
1464
1465 /* For indexed PNG data (PNG_COLOR_TYPE_PALETTE) many of the transformations
1466 * can be performed directly on the palette, and some (such as rgb to gray)
1467 * can be optimized inside the palette. This is particularly true of the
1468 * composite (background and alpha) stuff, which can be pretty much all done
1469 * in the palette even if the result is expanded to RGB or gray afterward.
1470 *
1471 * NOTE: this is Not Yet Implemented, the code behaves as in 1.5.1 and
1472 * earlier and the palette stuff is actually handled on the first row. This
1473 * leads to the reported bug that the palette returned by png_get_PLTE is not
1474 * updated.
1475 */
1476 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1477 png_init_palette_transformations(png_ptr);
1478
1479 else
1480 png_init_rgb_transformations(png_ptr);
1481
1482 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1483 defined(PNG_READ_EXPAND_16_SUPPORTED)
1484 if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
1485 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
1486 (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
1487 png_ptr->bit_depth != 16)
1488 {
1489 /* TODO: fix this. Because the expand_16 operation is after the compose
1490 * handling the background color must be 8, not 16, bits deep, but the
1491 * application will supply a 16-bit value so reduce it here.
1492 *
1493 * The PNG_BACKGROUND_EXPAND code above does not expand to 16 bits at
1494 * present, so that case is ok (until do_expand_16 is moved.)
1495 *
1496 * NOTE: this discards the low 16 bits of the user supplied background
1497 * color, but until expand_16 works properly there is no choice!
1498 */
1499 # define CHOP(x) (x)=((png_uint_16)PNG_DIV257(x))
1500 CHOP(png_ptr->background.red);
1501 CHOP(png_ptr->background.green);
1502 CHOP(png_ptr->background.blue);
1503 CHOP(png_ptr->background.gray);
1504 # undef CHOP
1505 }
1506 #endif /* READ_BACKGROUND && READ_EXPAND_16 */
1507
1508 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1509 (defined(PNG_READ_SCALE_16_TO_8_SUPPORTED) || \
1510 defined(PNG_READ_STRIP_16_TO_8_SUPPORTED))
1511 if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) != 0 &&
1512 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
1513 (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
1514 png_ptr->bit_depth == 16)
1515 {
1516 /* On the other hand, if a 16-bit file is to be reduced to 8-bits per
1517 * component this will also happen after PNG_COMPOSE and so the background
1518 * color must be pre-expanded here.
1519 *
1520 * TODO: fix this too.
1521 */
1522 png_ptr->background.red = (png_uint_16)(png_ptr->background.red * 257);
1523 png_ptr->background.green =
1524 (png_uint_16)(png_ptr->background.green * 257);
1525 png_ptr->background.blue = (png_uint_16)(png_ptr->background.blue * 257);
1526 png_ptr->background.gray = (png_uint_16)(png_ptr->background.gray * 257);
1527 }
1528 #endif
1529
1530 /* NOTE: below 'PNG_READ_ALPHA_MODE_SUPPORTED' is presumed to also enable the
1531 * background support (see the comments in scripts/pnglibconf.dfa), this
1532 * allows pre-multiplication of the alpha channel to be implemented as
1533 * compositing on black. This is probably sub-optimal and has been done in
1534 * 1.5.4 betas simply to enable external critique and testing (i.e. to
1535 * implement the new API quickly, without lots of internal changes.)
1536 */
1537
1538 #ifdef PNG_READ_GAMMA_SUPPORTED
1539 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1540 /* Includes ALPHA_MODE */
1541 png_ptr->background_1 = png_ptr->background;
1542 # endif
1543
1544 /* This needs to change - in the palette image case a whole set of tables are
1545 * built when it would be quicker to just calculate the correct value for
1546 * each palette entry directly. Also, the test is too tricky - why check
1547 * PNG_RGB_TO_GRAY if PNG_GAMMA is not set? The answer seems to be that
1548 * PNG_GAMMA is cancelled even if the gamma is known? The test excludes the
1549 * PNG_COMPOSE case, so apparently if there is no *overall* gamma correction
1550 * the gamma tables will not be built even if composition is required on a
1551 * gamma encoded value.
1552 *
1553 * In 1.5.4 this is addressed below by an additional check on the individual
1554 * file gamma - if it is not 1.0 both RGB_TO_GRAY and COMPOSE need the
1555 * tables.
1556 */
1557 if ((png_ptr->transformations & PNG_GAMMA) != 0 ||
1558 ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0 &&
1559 (png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
1560 png_gamma_significant(png_ptr->screen_gamma) != 0)) ||
1561 ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
1562 (png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
1563 png_gamma_significant(png_ptr->screen_gamma) != 0
1564 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1565 || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE &&
1566 png_gamma_significant(png_ptr->background_gamma) != 0)
1567 # endif
1568 )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 &&
1569 png_gamma_significant(png_ptr->screen_gamma) != 0))
1570 {
1571 png_build_gamma_table(png_ptr, png_ptr->bit_depth);
1572
1573 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1574 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1575 {
1576 /* Issue a warning about this combination: because RGB_TO_GRAY is
1577 * optimized to do the gamma transform if present yet do_background has
1578 * to do the same thing if both options are set a
1579 * double-gamma-correction happens. This is true in all versions of
1580 * libpng to date.
1581 */
1582 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
1583 png_warning(png_ptr,
1584 "libpng does not support gamma+background+rgb_to_gray");
1585
1586 if ((png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) != 0)
1587 {
1588 /* We don't get to here unless there is a tRNS chunk with non-opaque
1589 * entries - see the checking code at the start of this function.
1590 */
1591 png_color back, back_1;
1592 png_colorp palette = png_ptr->palette;
1593 int num_palette = png_ptr->num_palette;
1594 int i;
1595 if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_FILE)
1596 {
1597
1598 back.red = png_ptr->gamma_table[png_ptr->background.red];
1599 back.green = png_ptr->gamma_table[png_ptr->background.green];
1600 back.blue = png_ptr->gamma_table[png_ptr->background.blue];
1601
1602 back_1.red = png_ptr->gamma_to_1[png_ptr->background.red];
1603 back_1.green = png_ptr->gamma_to_1[png_ptr->background.green];
1604 back_1.blue = png_ptr->gamma_to_1[png_ptr->background.blue];
1605 }
1606 else
1607 {
1608 png_fixed_point g, gs;
1609
1610 switch (png_ptr->background_gamma_type)
1611 {
1612 case PNG_BACKGROUND_GAMMA_SCREEN:
1613 g = (png_ptr->screen_gamma);
1614 gs = PNG_FP_1;
1615 break;
1616
1617 case PNG_BACKGROUND_GAMMA_FILE:
1618 g = png_reciprocal(png_ptr->colorspace.gamma);
1619 gs = png_reciprocal2(png_ptr->colorspace.gamma,
1620 png_ptr->screen_gamma);
1621 break;
1622
1623 case PNG_BACKGROUND_GAMMA_UNIQUE:
1624 g = png_reciprocal(png_ptr->background_gamma);
1625 gs = png_reciprocal2(png_ptr->background_gamma,
1626 png_ptr->screen_gamma);
1627 break;
1628 default:
1629 g = PNG_FP_1; /* back_1 */
1630 gs = PNG_FP_1; /* back */
1631 break;
1632 }
1633
1634 if (png_gamma_significant(gs) != 0)
1635 {
1636 back.red = png_gamma_8bit_correct(png_ptr->background.red,
1637 gs);
1638 back.green = png_gamma_8bit_correct(png_ptr->background.green,
1639 gs);
1640 back.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1641 gs);
1642 }
1643
1644 else
1645 {
1646 back.red = (png_byte)png_ptr->background.red;
1647 back.green = (png_byte)png_ptr->background.green;
1648 back.blue = (png_byte)png_ptr->background.blue;
1649 }
1650
1651 if (png_gamma_significant(g) != 0)
1652 {
1653 back_1.red = png_gamma_8bit_correct(png_ptr->background.red,
1654 g);
1655 back_1.green = png_gamma_8bit_correct(
1656 png_ptr->background.green, g);
1657 back_1.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1658 g);
1659 }
1660
1661 else
1662 {
1663 back_1.red = (png_byte)png_ptr->background.red;
1664 back_1.green = (png_byte)png_ptr->background.green;
1665 back_1.blue = (png_byte)png_ptr->background.blue;
1666 }
1667 }
1668
1669 for (i = 0; i < num_palette; i++)
1670 {
1671 if (i < (int)png_ptr->num_trans &&
1672 png_ptr->trans_alpha[i] != 0xff)
1673 {
1674 if (png_ptr->trans_alpha[i] == 0)
1675 {
1676 palette[i] = back;
1677 }
1678 else /* if (png_ptr->trans_alpha[i] != 0xff) */
1679 {
1680 png_byte v, w;
1681
1682 v = png_ptr->gamma_to_1[palette[i].red];
1683 png_composite(w, v, png_ptr->trans_alpha[i], back_1.red);
1684 palette[i].red = png_ptr->gamma_from_1[w];
1685
1686 v = png_ptr->gamma_to_1[palette[i].green];
1687 png_composite(w, v, png_ptr->trans_alpha[i], back_1.green);
1688 palette[i].green = png_ptr->gamma_from_1[w];
1689
1690 v = png_ptr->gamma_to_1[palette[i].blue];
1691 png_composite(w, v, png_ptr->trans_alpha[i], back_1.blue);
1692 palette[i].blue = png_ptr->gamma_from_1[w];
1693 }
1694 }
1695 else
1696 {
1697 palette[i].red = png_ptr->gamma_table[palette[i].red];
1698 palette[i].green = png_ptr->gamma_table[palette[i].green];
1699 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1700 }
1701 }
1702
1703 /* Prevent the transformations being done again.
1704 *
1705 * NOTE: this is highly dubious; it removes the transformations in
1706 * place. This seems inconsistent with the general treatment of the
1707 * transformations elsewhere.
1708 */
1709 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_GAMMA);
1710 } /* color_type == PNG_COLOR_TYPE_PALETTE */
1711
1712 /* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */
1713 else /* color_type != PNG_COLOR_TYPE_PALETTE */
1714 {
1715 int gs_sig, g_sig;
1716 png_fixed_point g = PNG_FP_1; /* Correction to linear */
1717 png_fixed_point gs = PNG_FP_1; /* Correction to screen */
1718
1719 switch (png_ptr->background_gamma_type)
1720 {
1721 case PNG_BACKGROUND_GAMMA_SCREEN:
1722 g = png_ptr->screen_gamma;
1723 /* gs = PNG_FP_1; */
1724 break;
1725
1726 case PNG_BACKGROUND_GAMMA_FILE:
1727 g = png_reciprocal(png_ptr->colorspace.gamma);
1728 gs = png_reciprocal2(png_ptr->colorspace.gamma,
1729 png_ptr->screen_gamma);
1730 break;
1731
1732 case PNG_BACKGROUND_GAMMA_UNIQUE:
1733 g = png_reciprocal(png_ptr->background_gamma);
1734 gs = png_reciprocal2(png_ptr->background_gamma,
1735 png_ptr->screen_gamma);
1736 break;
1737
1738 default:
1739 png_error(png_ptr, "invalid background gamma type");
1740 }
1741
1742 g_sig = png_gamma_significant(g);
1743 gs_sig = png_gamma_significant(gs);
1744
1745 if (g_sig != 0)
1746 png_ptr->background_1.gray = png_gamma_correct(png_ptr,
1747 png_ptr->background.gray, g);
1748
1749 if (gs_sig != 0)
1750 png_ptr->background.gray = png_gamma_correct(png_ptr,
1751 png_ptr->background.gray, gs);
1752
1753 if ((png_ptr->background.red != png_ptr->background.green) ||
1754 (png_ptr->background.red != png_ptr->background.blue) ||
1755 (png_ptr->background.red != png_ptr->background.gray))
1756 {
1757 /* RGB or RGBA with color background */
1758 if (g_sig != 0)
1759 {
1760 png_ptr->background_1.red = png_gamma_correct(png_ptr,
1761 png_ptr->background.red, g);
1762
1763 png_ptr->background_1.green = png_gamma_correct(png_ptr,
1764 png_ptr->background.green, g);
1765
1766 png_ptr->background_1.blue = png_gamma_correct(png_ptr,
1767 png_ptr->background.blue, g);
1768 }
1769
1770 if (gs_sig != 0)
1771 {
1772 png_ptr->background.red = png_gamma_correct(png_ptr,
1773 png_ptr->background.red, gs);
1774
1775 png_ptr->background.green = png_gamma_correct(png_ptr,
1776 png_ptr->background.green, gs);
1777
1778 png_ptr->background.blue = png_gamma_correct(png_ptr,
1779 png_ptr->background.blue, gs);
1780 }
1781 }
1782
1783 else
1784 {
1785 /* GRAY, GRAY ALPHA, RGB, or RGBA with gray background */
1786 png_ptr->background_1.red = png_ptr->background_1.green
1787 = png_ptr->background_1.blue = png_ptr->background_1.gray;
1788
1789 png_ptr->background.red = png_ptr->background.green
1790 = png_ptr->background.blue = png_ptr->background.gray;
1791 }
1792
1793 /* The background is now in screen gamma: */
1794 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_SCREEN;
1795 } /* color_type != PNG_COLOR_TYPE_PALETTE */
1796 }/* png_ptr->transformations & PNG_BACKGROUND */
1797
1798 else
1799 /* Transformation does not include PNG_BACKGROUND */
1800 #endif /* READ_BACKGROUND */
1801 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE
1802 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1803 /* RGB_TO_GRAY needs to have non-gamma-corrected values! */
1804 && ((png_ptr->transformations & PNG_EXPAND) == 0 ||
1805 (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
1806 #endif
1807 )
1808 {
1809 png_colorp palette = png_ptr->palette;
1810 int num_palette = png_ptr->num_palette;
1811 int i;
1812
1813 /* NOTE: there are other transformations that should probably be in
1814 * here too.
1815 */
1816 for (i = 0; i < num_palette; i++)
1817 {
1818 palette[i].red = png_ptr->gamma_table[palette[i].red];
1819 palette[i].green = png_ptr->gamma_table[palette[i].green];
1820 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1821 }
1822
1823 /* Done the gamma correction. */
1824 png_ptr->transformations &= ~PNG_GAMMA;
1825 } /* color_type == PALETTE && !PNG_BACKGROUND transformation */
1826 }
1827 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1828 else
1829 #endif
1830 #endif /* READ_GAMMA */
1831
1832 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1833 /* No GAMMA transformation (see the hanging else 4 lines above) */
1834 if ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
1835 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1836 {
1837 int i;
1838 int istop = (int)png_ptr->num_trans;
1839 png_color back;
1840 png_colorp palette = png_ptr->palette;
1841
1842 back.red = (png_byte)png_ptr->background.red;
1843 back.green = (png_byte)png_ptr->background.green;
1844 back.blue = (png_byte)png_ptr->background.blue;
1845
1846 for (i = 0; i < istop; i++)
1847 {
1848 if (png_ptr->trans_alpha[i] == 0)
1849 {
1850 palette[i] = back;
1851 }
1852
1853 else if (png_ptr->trans_alpha[i] != 0xff)
1854 {
1855 /* The png_composite() macro is defined in png.h */
1856 png_composite(palette[i].red, palette[i].red,
1857 png_ptr->trans_alpha[i], back.red);
1858
1859 png_composite(palette[i].green, palette[i].green,
1860 png_ptr->trans_alpha[i], back.green);
1861
1862 png_composite(palette[i].blue, palette[i].blue,
1863 png_ptr->trans_alpha[i], back.blue);
1864 }
1865 }
1866
1867 png_ptr->transformations &= ~PNG_COMPOSE;
1868 }
1869 #endif /* READ_BACKGROUND */
1870
1871 #ifdef PNG_READ_SHIFT_SUPPORTED
1872 if ((png_ptr->transformations & PNG_SHIFT) != 0 &&
1873 (png_ptr->transformations & PNG_EXPAND) == 0 &&
1874 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1875 {
1876 int i;
1877 int istop = png_ptr->num_palette;
1878 int shift = 8 - png_ptr->sig_bit.red;
1879
1880 png_ptr->transformations &= ~PNG_SHIFT;
1881
1882 /* significant bits can be in the range 1 to 7 for a meaninful result, if
1883 * the number of significant bits is 0 then no shift is done (this is an
1884 * error condition which is silently ignored.)
1885 */
1886 if (shift > 0 && shift < 8)
1887 for (i=0; i<istop; ++i)
1888 {
1889 int component = png_ptr->palette[i].red;
1890
1891 component >>= shift;
1892 png_ptr->palette[i].red = (png_byte)component;
1893 }
1894
1895 shift = 8 - png_ptr->sig_bit.green;
1896 if (shift > 0 && shift < 8)
1897 for (i=0; i<istop; ++i)
1898 {
1899 int component = png_ptr->palette[i].green;
1900
1901 component >>= shift;
1902 png_ptr->palette[i].green = (png_byte)component;
1903 }
1904
1905 shift = 8 - png_ptr->sig_bit.blue;
1906 if (shift > 0 && shift < 8)
1907 for (i=0; i<istop; ++i)
1908 {
1909 int component = png_ptr->palette[i].blue;
1910
1911 component >>= shift;
1912 png_ptr->palette[i].blue = (png_byte)component;
1913 }
1914 }
1915 #endif /* READ_SHIFT */
1916 }
1917
1918 /* Modify the info structure to reflect the transformations. The
1919 * info should be updated so a PNG file could be written with it,
1920 * assuming the transformations result in valid PNG data.
1921 */
1922 void /* PRIVATE */
1923 png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
1924 {
1925 png_debug(1, "in png_read_transform_info");
1926
1927 #ifdef PNG_READ_EXPAND_SUPPORTED
1928 if ((png_ptr->transformations & PNG_EXPAND) != 0)
1929 {
1930 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1931 {
1932 /* This check must match what actually happens in
1933 * png_do_expand_palette; if it ever checks the tRNS chunk to see if
1934 * it is all opaque we must do the same (at present it does not.)
1935 */
1936 if (png_ptr->num_trans > 0)
1937 info_ptr->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
1938
1939 else
1940 info_ptr->color_type = PNG_COLOR_TYPE_RGB;
1941
1942 info_ptr->bit_depth = 8;
1943 info_ptr->num_trans = 0;
1944
1945 if (png_ptr->palette == NULL)
1946 png_error (png_ptr, "Palette is NULL in indexed image");
1947 }
1948 else
1949 {
1950 if (png_ptr->num_trans != 0)
1951 {
1952 if ((png_ptr->transformations & PNG_EXPAND_tRNS) != 0)
1953 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
1954 }
1955 if (info_ptr->bit_depth < 8)
1956 info_ptr->bit_depth = 8;
1957
1958 info_ptr->num_trans = 0;
1959 }
1960 }
1961 #endif
1962
1963 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
1964 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
1965 /* The following is almost certainly wrong unless the background value is in
1966 * the screen space!
1967 */
1968 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1969 info_ptr->background = png_ptr->background;
1970 #endif
1971
1972 #ifdef PNG_READ_GAMMA_SUPPORTED
1973 /* The following used to be conditional on PNG_GAMMA (prior to 1.5.4),
1974 * however it seems that the code in png_init_read_transformations, which has
1975 * been called before this from png_read_update_info->png_read_start_row
1976 * sometimes does the gamma transform and cancels the flag.
1977 *
1978 * TODO: this looks wrong; the info_ptr should end up with a gamma equal to
1979 * the screen_gamma value. The following probably results in weirdness if
1980 * the info_ptr is used by the app after the rows have been read.
1981 */
1982 info_ptr->colorspace.gamma = png_ptr->colorspace.gamma;
1983 #endif
1984
1985 if (info_ptr->bit_depth == 16)
1986 {
1987 # ifdef PNG_READ_16BIT_SUPPORTED
1988 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1989 if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0)
1990 info_ptr->bit_depth = 8;
1991 # endif
1992
1993 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1994 if ((png_ptr->transformations & PNG_16_TO_8) != 0)
1995 info_ptr->bit_depth = 8;
1996 # endif
1997
1998 # else
1999 /* No 16-bit support: force chopping 16-bit input down to 8, in this case
2000 * the app program can chose if both APIs are available by setting the
2001 * correct scaling to use.
2002 */
2003 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2004 /* For compatibility with previous versions use the strip method by
2005 * default. This code works because if PNG_SCALE_16_TO_8 is already
2006 * set the code below will do that in preference to the chop.
2007 */
2008 png_ptr->transformations |= PNG_16_TO_8;
2009 info_ptr->bit_depth = 8;
2010 # else
2011
2012 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2013 png_ptr->transformations |= PNG_SCALE_16_TO_8;
2014 info_ptr->bit_depth = 8;
2015 # else
2016
2017 CONFIGURATION ERROR: you must enable at least one 16 to 8 method
2018 # endif
2019 # endif
2020 #endif /* !READ_16BIT */
2021 }
2022
2023 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2024 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
2025 info_ptr->color_type = (png_byte)(info_ptr->color_type |
2026 PNG_COLOR_MASK_COLOR);
2027 #endif
2028
2029 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2030 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
2031 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2032 ~PNG_COLOR_MASK_COLOR);
2033 #endif
2034
2035 #ifdef PNG_READ_QUANTIZE_SUPPORTED
2036 if ((png_ptr->transformations & PNG_QUANTIZE) != 0)
2037 {
2038 if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
2039 (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) &&
2040 png_ptr->palette_lookup != 0 && info_ptr->bit_depth == 8)
2041 {
2042 info_ptr->color_type = PNG_COLOR_TYPE_PALETTE;
2043 }
2044 }
2045 #endif
2046
2047 #ifdef PNG_READ_EXPAND_16_SUPPORTED
2048 if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
2049 info_ptr->bit_depth == 8 &&
2050 info_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
2051 {
2052 info_ptr->bit_depth = 16;
2053 }
2054 #endif
2055
2056 #ifdef PNG_READ_PACK_SUPPORTED
2057 if ((png_ptr->transformations & PNG_PACK) != 0 &&
2058 (info_ptr->bit_depth < 8))
2059 info_ptr->bit_depth = 8;
2060 #endif
2061
2062 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
2063 info_ptr->channels = 1;
2064
2065 else if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
2066 info_ptr->channels = 3;
2067
2068 else
2069 info_ptr->channels = 1;
2070
2071 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
2072 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0)
2073 {
2074 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2075 ~PNG_COLOR_MASK_ALPHA);
2076 info_ptr->num_trans = 0;
2077 }
2078 #endif
2079
2080 if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
2081 info_ptr->channels++;
2082
2083 #ifdef PNG_READ_FILLER_SUPPORTED
2084 /* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */
2085 if ((png_ptr->transformations & PNG_FILLER) != 0 &&
2086 (info_ptr->color_type == PNG_COLOR_TYPE_RGB ||
2087 info_ptr->color_type == PNG_COLOR_TYPE_GRAY))
2088 {
2089 info_ptr->channels++;
2090 /* If adding a true alpha channel not just filler */
2091 if ((png_ptr->transformations & PNG_ADD_ALPHA) != 0)
2092 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
2093 }
2094 #endif
2095
2096 #if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \
2097 defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
2098 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
2099 {
2100 if (png_ptr->user_transform_depth != 0)
2101 info_ptr->bit_depth = png_ptr->user_transform_depth;
2102
2103 if (png_ptr->user_transform_channels != 0)
2104 info_ptr->channels = png_ptr->user_transform_channels;
2105 }
2106 #endif
2107
2108 info_ptr->pixel_depth = (png_byte)(info_ptr->channels *
2109 info_ptr->bit_depth);
2110
2111 info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, info_ptr->width);
2112
2113 /* Adding in 1.5.4: cache the above value in png_struct so that we can later
2114 * check in png_rowbytes that the user buffer won't get overwritten. Note
2115 * that the field is not always set - if png_read_update_info isn't called
2116 * the application has to either not do any transforms or get the calculation
2117 * right itself.
2118 */
2119 png_ptr->info_rowbytes = info_ptr->rowbytes;
2120
2121 #ifndef PNG_READ_EXPAND_SUPPORTED
2122 if (png_ptr != NULL)
2123 return;
2124 #endif
2125 }
2126
2127 #ifdef PNG_READ_PACK_SUPPORTED
2128 /* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
2129 * without changing the actual values. Thus, if you had a row with
2130 * a bit depth of 1, you would end up with bytes that only contained
2131 * the numbers 0 or 1. If you would rather they contain 0 and 255, use
2132 * png_do_shift() after this.
2133 */
2134 static void
2135 png_do_unpack(png_row_infop row_info, png_bytep row)
2136 {
2137 png_debug(1, "in png_do_unpack");
2138
2139 if (row_info->bit_depth < 8)
2140 {
2141 png_uint_32 i;
2142 png_uint_32 row_width=row_info->width;
2143
2144 switch (row_info->bit_depth)
2145 {
2146 case 1:
2147 {
2148 png_bytep sp = row + (png_size_t)((row_width - 1) >> 3);
2149 png_bytep dp = row + (png_size_t)row_width - 1;
2150 png_uint_32 shift = 7 - (int)((row_width + 7) & 0x07);
2151 for (i = 0; i < row_width; i++)
2152 {
2153 *dp = (png_byte)((*sp >> shift) & 0x01);
2154
2155 if (shift == 7)
2156 {
2157 shift = 0;
2158 sp--;
2159 }
2160
2161 else
2162 shift++;
2163
2164 dp--;
2165 }
2166 break;
2167 }
2168
2169 case 2:
2170 {
2171
2172 png_bytep sp = row + (png_size_t)((row_width - 1) >> 2);
2173 png_bytep dp = row + (png_size_t)row_width - 1;
2174 png_uint_32 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
2175 for (i = 0; i < row_width; i++)
2176 {
2177 *dp = (png_byte)((*sp >> shift) & 0x03);
2178
2179 if (shift == 6)
2180 {
2181 shift = 0;
2182 sp--;
2183 }
2184
2185 else
2186 shift += 2;
2187
2188 dp--;
2189 }
2190 break;
2191 }
2192
2193 case 4:
2194 {
2195 png_bytep sp = row + (png_size_t)((row_width - 1) >> 1);
2196 png_bytep dp = row + (png_size_t)row_width - 1;
2197 png_uint_32 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
2198 for (i = 0; i < row_width; i++)
2199 {
2200 *dp = (png_byte)((*sp >> shift) & 0x0f);
2201
2202 if (shift == 4)
2203 {
2204 shift = 0;
2205 sp--;
2206 }
2207
2208 else
2209 shift = 4;
2210
2211 dp--;
2212 }
2213 break;
2214 }
2215
2216 default:
2217 break;
2218 }
2219 row_info->bit_depth = 8;
2220 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2221 row_info->rowbytes = row_width * row_info->channels;
2222 }
2223 }
2224 #endif
2225
2226 #ifdef PNG_READ_SHIFT_SUPPORTED
2227 /* Reverse the effects of png_do_shift. This routine merely shifts the
2228 * pixels back to their significant bits values. Thus, if you have
2229 * a row of bit depth 8, but only 5 are significant, this will shift
2230 * the values back to 0 through 31.
2231 */
2232 static void
2233 png_do_unshift(png_row_infop row_info, png_bytep row,
2234 png_const_color_8p sig_bits)
2235 {
2236 int color_type;
2237
2238 png_debug(1, "in png_do_unshift");
2239
2240 /* The palette case has already been handled in the _init routine. */
2241 color_type = row_info->color_type;
2242
2243 if (color_type != PNG_COLOR_TYPE_PALETTE)
2244 {
2245 int shift[4];
2246 int channels = 0;
2247 int bit_depth = row_info->bit_depth;
2248
2249 if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
2250 {
2251 shift[channels++] = bit_depth - sig_bits->red;
2252 shift[channels++] = bit_depth - sig_bits->green;
2253 shift[channels++] = bit_depth - sig_bits->blue;
2254 }
2255
2256 else
2257 {
2258 shift[channels++] = bit_depth - sig_bits->gray;
2259 }
2260
2261 if ((color_type & PNG_COLOR_MASK_ALPHA) != 0)
2262 {
2263 shift[channels++] = bit_depth - sig_bits->alpha;
2264 }
2265
2266 {
2267 int c, have_shift;
2268
2269 for (c = have_shift = 0; c < channels; ++c)
2270 {
2271 /* A shift of more than the bit depth is an error condition but it
2272 * gets ignored here.
2273 */
2274 if (shift[c] <= 0 || shift[c] >= bit_depth)
2275 shift[c] = 0;
2276
2277 else
2278 have_shift = 1;
2279 }
2280
2281 if (have_shift == 0)
2282 return;
2283 }
2284
2285 switch (bit_depth)
2286 {
2287 default:
2288 /* Must be 1bpp gray: should not be here! */
2289 /* NOTREACHED */
2290 break;
2291
2292 case 2:
2293 /* Must be 2bpp gray */
2294 /* assert(channels == 1 && shift[0] == 1) */
2295 {
2296 png_bytep bp = row;
2297 png_bytep bp_end = bp + row_info->rowbytes;
2298
2299 while (bp < bp_end)
2300 {
2301 int b = (*bp >> 1) & 0x55;
2302 *bp++ = (png_byte)b;
2303 }
2304 break;
2305 }
2306
2307 case 4:
2308 /* Must be 4bpp gray */
2309 /* assert(channels == 1) */
2310 {
2311 png_bytep bp = row;
2312 png_bytep bp_end = bp + row_info->rowbytes;
2313 int gray_shift = shift[0];
2314 int mask = 0xf >> gray_shift;
2315
2316 mask |= mask << 4;
2317
2318 while (bp < bp_end)
2319 {
2320 int b = (*bp >> gray_shift) & mask;
2321 *bp++ = (png_byte)b;
2322 }
2323 break;
2324 }
2325
2326 case 8:
2327 /* Single byte components, G, GA, RGB, RGBA */
2328 {
2329 png_bytep bp = row;
2330 png_bytep bp_end = bp + row_info->rowbytes;
2331 int channel = 0;
2332
2333 while (bp < bp_end)
2334 {
2335 int b = *bp >> shift[channel];
2336 if (++channel >= channels)
2337 channel = 0;
2338 *bp++ = (png_byte)b;
2339 }
2340 break;
2341 }
2342
2343 #ifdef PNG_READ_16BIT_SUPPORTED
2344 case 16:
2345 /* Double byte components, G, GA, RGB, RGBA */
2346 {
2347 png_bytep bp = row;
2348 png_bytep bp_end = bp + row_info->rowbytes;
2349 int channel = 0;
2350
2351 while (bp < bp_end)
2352 {
2353 int value = (bp[0] << 8) + bp[1];
2354
2355 value >>= shift[channel];
2356 if (++channel >= channels)
2357 channel = 0;
2358 *bp++ = (png_byte)(value >> 8);
2359 *bp++ = (png_byte)value;
2360 }
2361 break;
2362 }
2363 #endif
2364 }
2365 }
2366 }
2367 #endif
2368
2369 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2370 /* Scale rows of bit depth 16 down to 8 accurately */
2371 static void
2372 png_do_scale_16_to_8(png_row_infop row_info, png_bytep row)
2373 {
2374 png_debug(1, "in png_do_scale_16_to_8");
2375
2376 if (row_info->bit_depth == 16)
2377 {
2378 png_bytep sp = row; /* source */
2379 png_bytep dp = row; /* destination */
2380 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2381
2382 while (sp < ep)
2383 {
2384 /* The input is an array of 16-bit components, these must be scaled to
2385 * 8 bits each. For a 16-bit value V the required value (from the PNG
2386 * specification) is:
2387 *
2388 * (V * 255) / 65535
2389 *
2390 * This reduces to round(V / 257), or floor((V + 128.5)/257)
2391 *
2392 * Represent V as the two byte value vhi.vlo. Make a guess that the
2393 * result is the top byte of V, vhi, then the correction to this value
2394 * is:
2395 *
2396 * error = floor(((V-vhi.vhi) + 128.5) / 257)
2397 * = floor(((vlo-vhi) + 128.5) / 257)
2398 *
2399 * This can be approximated using integer arithmetic (and a signed
2400 * shift):
2401 *
2402 * error = (vlo-vhi+128) >> 8;
2403 *
2404 * The approximate differs from the exact answer only when (vlo-vhi) is
2405 * 128; it then gives a correction of +1 when the exact correction is
2406 * 0. This gives 128 errors. The exact answer (correct for all 16-bit
2407 * input values) is:
2408 *
2409 * error = (vlo-vhi+128)*65535 >> 24;
2410 *
2411 * An alternative arithmetic calculation which also gives no errors is:
2412 *
2413 * (V * 255 + 32895) >> 16
2414 */
2415
2416 png_int_32 tmp = *sp++; /* must be signed! */
2417 tmp += (((int)*sp++ - tmp + 128) * 65535) >> 24;
2418 *dp++ = (png_byte)tmp;
2419 }
2420
2421 row_info->bit_depth = 8;
2422 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2423 row_info->rowbytes = row_info->width * row_info->channels;
2424 }
2425 }
2426 #endif
2427
2428 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2429 static void
2430 /* Simply discard the low byte. This was the default behavior prior
2431 * to libpng-1.5.4.
2432 */
2433 png_do_chop(png_row_infop row_info, png_bytep row)
2434 {
2435 png_debug(1, "in png_do_chop");
2436
2437 if (row_info->bit_depth == 16)
2438 {
2439 png_bytep sp = row; /* source */
2440 png_bytep dp = row; /* destination */
2441 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2442
2443 while (sp < ep)
2444 {
2445 *dp++ = *sp;
2446 sp += 2; /* skip low byte */
2447 }
2448
2449 row_info->bit_depth = 8;
2450 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2451 row_info->rowbytes = row_info->width * row_info->channels;
2452 }
2453 }
2454 #endif
2455
2456 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
2457 static void
2458 png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
2459 {
2460 png_debug(1, "in png_do_read_swap_alpha");
2461
2462 {
2463 png_uint_32 row_width = row_info->width;
2464 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2465 {
2466 /* This converts from RGBA to ARGB */
2467 if (row_info->bit_depth == 8)
2468 {
2469 png_bytep sp = row + row_info->rowbytes;
2470 png_bytep dp = sp;
2471 png_byte save;
2472 png_uint_32 i;
2473
2474 for (i = 0; i < row_width; i++)
2475 {
2476 save = *(--sp);
2477 *(--dp) = *(--sp);
2478 *(--dp) = *(--sp);
2479 *(--dp) = *(--sp);
2480 *(--dp) = save;
2481 }
2482 }
2483
2484 #ifdef PNG_READ_16BIT_SUPPORTED
2485 /* This converts from RRGGBBAA to AARRGGBB */
2486 else
2487 {
2488 png_bytep sp = row + row_info->rowbytes;
2489 png_bytep dp = sp;
2490 png_byte save[2];
2491 png_uint_32 i;
2492
2493 for (i = 0; i < row_width; i++)
2494 {
2495 save[0] = *(--sp);
2496 save[1] = *(--sp);
2497 *(--dp) = *(--sp);
2498 *(--dp) = *(--sp);
2499 *(--dp) = *(--sp);
2500 *(--dp) = *(--sp);
2501 *(--dp) = *(--sp);
2502 *(--dp) = *(--sp);
2503 *(--dp) = save[0];
2504 *(--dp) = save[1];
2505 }
2506 }
2507 #endif
2508 }
2509
2510 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2511 {
2512 /* This converts from GA to AG */
2513 if (row_info->bit_depth == 8)
2514 {
2515 png_bytep sp = row + row_info->rowbytes;
2516 png_bytep dp = sp;
2517 png_byte save;
2518 png_uint_32 i;
2519
2520 for (i = 0; i < row_width; i++)
2521 {
2522 save = *(--sp);
2523 *(--dp) = *(--sp);
2524 *(--dp) = save;
2525 }
2526 }
2527
2528 #ifdef PNG_READ_16BIT_SUPPORTED
2529 /* This converts from GGAA to AAGG */
2530 else
2531 {
2532 png_bytep sp = row + row_info->rowbytes;
2533 png_bytep dp = sp;
2534 png_byte save[2];
2535 png_uint_32 i;
2536
2537 for (i = 0; i < row_width; i++)
2538 {
2539 save[0] = *(--sp);
2540 save[1] = *(--sp);
2541 *(--dp) = *(--sp);
2542 *(--dp) = *(--sp);
2543 *(--dp) = save[0];
2544 *(--dp) = save[1];
2545 }
2546 }
2547 #endif
2548 }
2549 }
2550 }
2551 #endif
2552
2553 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
2554 static void
2555 png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
2556 {
2557 png_uint_32 row_width;
2558 png_debug(1, "in png_do_read_invert_alpha");
2559
2560 row_width = row_info->width;
2561 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2562 {
2563 if (row_info->bit_depth == 8)
2564 {
2565 /* This inverts the alpha channel in RGBA */
2566 png_bytep sp = row + row_info->rowbytes;
2567 png_bytep dp = sp;
2568 png_uint_32 i;
2569
2570 for (i = 0; i < row_width; i++)
2571 {
2572 *(--dp) = (png_byte)(255 - *(--sp));
2573
2574 /* This does nothing:
2575 *(--dp) = *(--sp);
2576 *(--dp) = *(--sp);
2577 *(--dp) = *(--sp);
2578 We can replace it with:
2579 */
2580 sp-=3;
2581 dp=sp;
2582 }
2583 }
2584
2585 #ifdef PNG_READ_16BIT_SUPPORTED
2586 /* This inverts the alpha channel in RRGGBBAA */
2587 else
2588 {
2589 png_bytep sp = row + row_info->rowbytes;
2590 png_bytep dp = sp;
2591 png_uint_32 i;
2592
2593 for (i = 0; i < row_width; i++)
2594 {
2595 *(--dp) = (png_byte)(255 - *(--sp));
2596 *(--dp) = (png_byte)(255 - *(--sp));
2597
2598 /* This does nothing:
2599 *(--dp) = *(--sp);
2600 *(--dp) = *(--sp);
2601 *(--dp) = *(--sp);
2602 *(--dp) = *(--sp);
2603 *(--dp) = *(--sp);
2604 *(--dp) = *(--sp);
2605 We can replace it with:
2606 */
2607 sp-=6;
2608 dp=sp;
2609 }
2610 }
2611 #endif
2612 }
2613 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2614 {
2615 if (row_info->bit_depth == 8)
2616 {
2617 /* This inverts the alpha channel in GA */
2618 png_bytep sp = row + row_info->rowbytes;
2619 png_bytep dp = sp;
2620 png_uint_32 i;
2621
2622 for (i = 0; i < row_width; i++)
2623 {
2624 *(--dp) = (png_byte)(255 - *(--sp));
2625 *(--dp) = *(--sp);
2626 }
2627 }
2628
2629 #ifdef PNG_READ_16BIT_SUPPORTED
2630 else
2631 {
2632 /* This inverts the alpha channel in GGAA */
2633 png_bytep sp = row + row_info->rowbytes;
2634 png_bytep dp = sp;
2635 png_uint_32 i;
2636
2637 for (i = 0; i < row_width; i++)
2638 {
2639 *(--dp) = (png_byte)(255 - *(--sp));
2640 *(--dp) = (png_byte)(255 - *(--sp));
2641 /*
2642 *(--dp) = *(--sp);
2643 *(--dp) = *(--sp);
2644 */
2645 sp-=2;
2646 dp=sp;
2647 }
2648 }
2649 #endif
2650 }
2651 }
2652 #endif
2653
2654 #ifdef PNG_READ_FILLER_SUPPORTED
2655 /* Add filler channel if we have RGB color */
2656 static void
2657 png_do_read_filler(png_row_infop row_info, png_bytep row,
2658 png_uint_32 filler, png_uint_32 flags)
2659 {
2660 png_uint_32 i;
2661 png_uint_32 row_width = row_info->width;
2662
2663 #ifdef PNG_READ_16BIT_SUPPORTED
2664 png_byte hi_filler = (png_byte)(filler>>8);
2665 #endif
2666 png_byte lo_filler = (png_byte)filler;
2667
2668 png_debug(1, "in png_do_read_filler");
2669
2670 if (
2671 row_info->color_type == PNG_COLOR_TYPE_GRAY)
2672 {
2673 if (row_info->bit_depth == 8)
2674 {
2675 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2676 {
2677 /* This changes the data from G to GX */
2678 png_bytep sp = row + (png_size_t)row_width;
2679 png_bytep dp = sp + (png_size_t)row_width;
2680 for (i = 1; i < row_width; i++)
2681 {
2682 *(--dp) = lo_filler;
2683 *(--dp) = *(--sp);
2684 }
2685 *(--dp) = lo_filler;
2686 row_info->channels = 2;
2687 row_info->pixel_depth = 16;
2688 row_info->rowbytes = row_width * 2;
2689 }
2690
2691 else
2692 {
2693 /* This changes the data from G to XG */
2694 png_bytep sp = row + (png_size_t)row_width;
2695 png_bytep dp = sp + (png_size_t)row_width;
2696 for (i = 0; i < row_width; i++)
2697 {
2698 *(--dp) = *(--sp);
2699 *(--dp) = lo_filler;
2700 }
2701 row_info->channels = 2;
2702 row_info->pixel_depth = 16;
2703 row_info->rowbytes = row_width * 2;
2704 }
2705 }
2706
2707 #ifdef PNG_READ_16BIT_SUPPORTED
2708 else if (row_info->bit_depth == 16)
2709 {
2710 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2711 {
2712 /* This changes the data from GG to GGXX */
2713 png_bytep sp = row + (png_size_t)row_width * 2;
2714 png_bytep dp = sp + (png_size_t)row_width * 2;
2715 for (i = 1; i < row_width; i++)
2716 {
2717 *(--dp) = lo_filler;
2718 *(--dp) = hi_filler;
2719 *(--dp) = *(--sp);
2720 *(--dp) = *(--sp);
2721 }
2722 *(--dp) = lo_filler;
2723 *(--dp) = hi_filler;
2724 row_info->channels = 2;
2725 row_info->pixel_depth = 32;
2726 row_info->rowbytes = row_width * 4;
2727 }
2728
2729 else
2730 {
2731 /* This changes the data from GG to XXGG */
2732 png_bytep sp = row + (png_size_t)row_width * 2;
2733 png_bytep dp = sp + (png_size_t)row_width * 2;
2734 for (i = 0; i < row_width; i++)
2735 {
2736 *(--dp) = *(--sp);
2737 *(--dp) = *(--sp);
2738 *(--dp) = lo_filler;
2739 *(--dp) = hi_filler;
2740 }
2741 row_info->channels = 2;
2742 row_info->pixel_depth = 32;
2743 row_info->rowbytes = row_width * 4;
2744 }
2745 }
2746 #endif
2747 } /* COLOR_TYPE == GRAY */
2748 else if (row_info->color_type == PNG_COLOR_TYPE_RGB)
2749 {
2750 if (row_info->bit_depth == 8)
2751 {
2752 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2753 {
2754 /* This changes the data from RGB to RGBX */
2755 png_bytep sp = row + (png_size_t)row_width * 3;
2756 png_bytep dp = sp + (png_size_t)row_width;
2757 for (i = 1; i < row_width; i++)
2758 {
2759 *(--dp) = lo_filler;
2760 *(--dp) = *(--sp);
2761 *(--dp) = *(--sp);
2762 *(--dp) = *(--sp);
2763 }
2764 *(--dp) = lo_filler;
2765 row_info->channels = 4;
2766 row_info->pixel_depth = 32;
2767 row_info->rowbytes = row_width * 4;
2768 }
2769
2770 else
2771 {
2772 /* This changes the data from RGB to XRGB */
2773 png_bytep sp = row + (png_size_t)row_width * 3;
2774 png_bytep dp = sp + (png_size_t)row_width;
2775 for (i = 0; i < row_width; i++)
2776 {
2777 *(--dp) = *(--sp);
2778 *(--dp) = *(--sp);
2779 *(--dp) = *(--sp);
2780 *(--dp) = lo_filler;
2781 }
2782 row_info->channels = 4;
2783 row_info->pixel_depth = 32;
2784 row_info->rowbytes = row_width * 4;
2785 }
2786 }
2787
2788 #ifdef PNG_READ_16BIT_SUPPORTED
2789 else if (row_info->bit_depth == 16)
2790 {
2791 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2792 {
2793 /* This changes the data from RRGGBB to RRGGBBXX */
2794 png_bytep sp = row + (png_size_t)row_width * 6;
2795 png_bytep dp = sp + (png_size_t)row_width * 2;
2796 for (i = 1; i < row_width; i++)
2797 {
2798 *(--dp) = lo_filler;
2799 *(--dp) = hi_filler;
2800 *(--dp) = *(--sp);
2801 *(--dp) = *(--sp);
2802 *(--dp) = *(--sp);
2803 *(--dp) = *(--sp);
2804 *(--dp) = *(--sp);
2805 *(--dp) = *(--sp);
2806 }
2807 *(--dp) = lo_filler;
2808 *(--dp) = hi_filler;
2809 row_info->channels = 4;
2810 row_info->pixel_depth = 64;
2811 row_info->rowbytes = row_width * 8;
2812 }
2813
2814 else
2815 {
2816 /* This changes the data from RRGGBB to XXRRGGBB */
2817 png_bytep sp = row + (png_size_t)row_width * 6;
2818 png_bytep dp = sp + (png_size_t)row_width * 2;
2819 for (i = 0; i < row_width; i++)
2820 {
2821 *(--dp) = *(--sp);
2822 *(--dp) = *(--sp);
2823 *(--dp) = *(--sp);
2824 *(--dp) = *(--sp);
2825 *(--dp) = *(--sp);
2826 *(--dp) = *(--sp);
2827 *(--dp) = lo_filler;
2828 *(--dp) = hi_filler;
2829 }
2830
2831 row_info->channels = 4;
2832 row_info->pixel_depth = 64;
2833 row_info->rowbytes = row_width * 8;
2834 }
2835 }
2836 #endif
2837 } /* COLOR_TYPE == RGB */
2838 }
2839 #endif
2840
2841 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2842 /* Expand grayscale files to RGB, with or without alpha */
2843 static void
2844 png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
2845 {
2846 png_uint_32 i;
2847 png_uint_32 row_width = row_info->width;
2848
2849 png_debug(1, "in png_do_gray_to_rgb");
2850
2851 if (row_info->bit_depth >= 8 &&
2852 (row_info->color_type & PNG_COLOR_MASK_COLOR) == 0)
2853 {
2854 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
2855 {
2856 if (row_info->bit_depth == 8)
2857 {
2858 /* This changes G to RGB */
2859 png_bytep sp = row + (png_size_t)row_width - 1;
2860 png_bytep dp = sp + (png_size_t)row_width * 2;
2861 for (i = 0; i < row_width; i++)
2862 {
2863 *(dp--) = *sp;
2864 *(dp--) = *sp;
2865 *(dp--) = *(sp--);
2866 }
2867 }
2868
2869 else
2870 {
2871 /* This changes GG to RRGGBB */
2872 png_bytep sp = row + (png_size_t)row_width * 2 - 1;
2873 png_bytep dp = sp + (png_size_t)row_width * 4;
2874 for (i = 0; i < row_width; i++)
2875 {
2876 *(dp--) = *sp;
2877 *(dp--) = *(sp - 1);
2878 *(dp--) = *sp;
2879 *(dp--) = *(sp - 1);
2880 *(dp--) = *(sp--);
2881 *(dp--) = *(sp--);
2882 }
2883 }
2884 }
2885
2886 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2887 {
2888 if (row_info->bit_depth == 8)
2889 {
2890 /* This changes GA to RGBA */
2891 png_bytep sp = row + (png_size_t)row_width * 2 - 1;
2892 png_bytep dp = sp + (png_size_t)row_width * 2;
2893 for (i = 0; i < row_width; i++)
2894 {
2895 *(dp--) = *(sp--);
2896 *(dp--) = *sp;
2897 *(dp--) = *sp;
2898 *(dp--) = *(sp--);
2899 }
2900 }
2901
2902 else
2903 {
2904 /* This changes GGAA to RRGGBBAA */
2905 png_bytep sp = row + (png_size_t)row_width * 4 - 1;
2906 png_bytep dp = sp + (png_size_t)row_width * 4;
2907 for (i = 0; i < row_width; i++)
2908 {
2909 *(dp--) = *(sp--);
2910 *(dp--) = *(sp--);
2911 *(dp--) = *sp;
2912 *(dp--) = *(sp - 1);
2913 *(dp--) = *sp;
2914 *(dp--) = *(sp - 1);
2915 *(dp--) = *(sp--);
2916 *(dp--) = *(sp--);
2917 }
2918 }
2919 }
2920 row_info->channels = (png_byte)(row_info->channels + 2);
2921 row_info->color_type |= PNG_COLOR_MASK_COLOR;
2922 row_info->pixel_depth = (png_byte)(row_info->channels *
2923 row_info->bit_depth);
2924 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
2925 }
2926 }
2927 #endif
2928
2929 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2930 /* Reduce RGB files to grayscale, with or without alpha
2931 * using the equation given in Poynton's ColorFAQ of 1998-01-04 at
2932 * <http://www.inforamp.net/~poynton/> (THIS LINK IS DEAD June 2008 but
2933 * versions dated 1998 through November 2002 have been archived at
2934 * http://web.archive.org/web/20000816232553/http://www.inforamp.net/
2935 * ~poynton/notes/colour_and_gamma/ColorFAQ.txt )
2936 * Charles Poynton poynton at poynton.com
2937 *
2938 * Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
2939 *
2940 * which can be expressed with integers as
2941 *
2942 * Y = (6969 * R + 23434 * G + 2365 * B)/32768
2943 *
2944 * Poynton's current link (as of January 2003 through July 2011):
2945 * <http://www.poynton.com/notes/colour_and_gamma/>
2946 * has changed the numbers slightly:
2947 *
2948 * Y = 0.2126*R + 0.7152*G + 0.0722*B
2949 *
2950 * which can be expressed with integers as
2951 *
2952 * Y = (6966 * R + 23436 * G + 2366 * B)/32768
2953 *
2954 * Historically, however, libpng uses numbers derived from the ITU-R Rec 709
2955 * end point chromaticities and the D65 white point. Depending on the
2956 * precision used for the D65 white point this produces a variety of different
2957 * numbers, however if the four decimal place value used in ITU-R Rec 709 is
2958 * used (0.3127,0.3290) the Y calculation would be:
2959 *
2960 * Y = (6968 * R + 23435 * G + 2366 * B)/32768
2961 *
2962 * While this is correct the rounding results in an overflow for white, because
2963 * the sum of the rounded coefficients is 32769, not 32768. Consequently
2964 * libpng uses, instead, the closest non-overflowing approximation:
2965 *
2966 * Y = (6968 * R + 23434 * G + 2366 * B)/32768
2967 *
2968 * Starting with libpng-1.5.5, if the image being converted has a cHRM chunk
2969 * (including an sRGB chunk) then the chromaticities are used to calculate the
2970 * coefficients. See the chunk handling in pngrutil.c for more information.
2971 *
2972 * In all cases the calculation is to be done in a linear colorspace. If no
2973 * gamma information is available to correct the encoding of the original RGB
2974 * values this results in an implicit assumption that the original PNG RGB
2975 * values were linear.
2976 *
2977 * Other integer coefficents can be used via png_set_rgb_to_gray(). Because
2978 * the API takes just red and green coefficients the blue coefficient is
2979 * calculated to make the sum 32768. This will result in different rounding
2980 * to that used above.
2981 */
2982 static int
2983 png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
2984
2985 {
2986 int rgb_error = 0;
2987
2988 png_debug(1, "in png_do_rgb_to_gray");
2989
2990 if ((row_info->color_type & PNG_COLOR_MASK_PALETTE) == 0 &&
2991 (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
2992 {
2993 PNG_CONST png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff;
2994 PNG_CONST png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff;
2995 PNG_CONST png_uint_32 bc = 32768 - rc - gc;
2996 PNG_CONST png_uint_32 row_width = row_info->width;
2997 PNG_CONST int have_alpha =
2998 (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0;
2999
3000 if (row_info->bit_depth == 8)
3001 {
3002 #ifdef PNG_READ_GAMMA_SUPPORTED
3003 /* Notice that gamma to/from 1 are not necessarily inverses (if
3004 * there is an overall gamma correction). Prior to 1.5.5 this code
3005 * checked the linearized values for equality; this doesn't match
3006 * the documentation, the original values must be checked.
3007 */
3008 if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL)
3009 {
3010 png_bytep sp = row;
3011 png_bytep dp = row;
3012 png_uint_32 i;
3013
3014 for (i = 0; i < row_width; i++)
3015 {
3016 png_byte red = *(sp++);
3017 png_byte green = *(sp++);
3018 png_byte blue = *(sp++);
3019
3020 if (red != green || red != blue)
3021 {
3022 red = png_ptr->gamma_to_1[red];
3023 green = png_ptr->gamma_to_1[green];
3024 blue = png_ptr->gamma_to_1[blue];
3025
3026 rgb_error |= 1;
3027 *(dp++) = png_ptr->gamma_from_1[
3028 (rc*red + gc*green + bc*blue + 16384)>>15];
3029 }
3030
3031 else
3032 {
3033 /* If there is no overall correction the table will not be
3034 * set.
3035 */
3036 if (png_ptr->gamma_table != NULL)
3037 red = png_ptr->gamma_table[red];
3038
3039 *(dp++) = red;
3040 }
3041
3042 if (have_alpha != 0)
3043 *(dp++) = *(sp++);
3044 }
3045 }
3046 else
3047 #endif
3048 {
3049 png_bytep sp = row;
3050 png_bytep dp = row;
3051 png_uint_32 i;
3052
3053 for (i = 0; i < row_width; i++)
3054 {
3055 png_byte red = *(sp++);
3056 png_byte green = *(sp++);
3057 png_byte blue = *(sp++);
3058
3059 if (red != green || red != blue)
3060 {
3061 rgb_error |= 1;
3062 /* NOTE: this is the historical approach which simply
3063 * truncates the results.
3064 */
3065 *(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15);
3066 }
3067
3068 else
3069 *(dp++) = red;
3070
3071 if (have_alpha != 0)
3072 *(dp++) = *(sp++);
3073 }
3074 }
3075 }
3076
3077 else /* RGB bit_depth == 16 */
3078 {
3079 #ifdef PNG_READ_GAMMA_SUPPORTED
3080 if (png_ptr->gamma_16_to_1 != NULL && png_ptr->gamma_16_from_1 != NULL)
3081 {
3082 png_bytep sp = row;
3083 png_bytep dp = row;
3084 png_uint_32 i;
3085
3086 for (i = 0; i < row_width; i++)
3087 {
3088 png_uint_16 red, green, blue, w;
3089 png_byte hi,lo;
3090
3091 hi=*(sp)++; lo=*(sp)++; red = (png_uint_16)((hi << 8) | (lo));
3092 hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo));
3093 hi=*(sp)++; lo=*(sp)++; blue = (png_uint_16)((hi << 8) | (lo));
3094
3095 if (red == green && red == blue)
3096 {
3097 if (png_ptr->gamma_16_table != NULL)
3098 w = png_ptr->gamma_16_table[(red & 0xff)
3099 >> png_ptr->gamma_shift][red >> 8];
3100
3101 else
3102 w = red;
3103 }
3104
3105 else
3106 {
3107 png_uint_16 red_1 = png_ptr->gamma_16_to_1[(red & 0xff)
3108 >> png_ptr->gamma_shift][red>>8];
3109 png_uint_16 green_1 =
3110 png_ptr->gamma_16_to_1[(green & 0xff) >>
3111 png_ptr->gamma_shift][green>>8];
3112 png_uint_16 blue_1 = png_ptr->gamma_16_to_1[(blue & 0xff)
3113 >> png_ptr->gamma_shift][blue>>8];
3114 png_uint_16 gray16 = (png_uint_16)((rc*red_1 + gc*green_1
3115 + bc*blue_1 + 16384)>>15);
3116 w = png_ptr->gamma_16_from_1[(gray16 & 0xff) >>
3117 png_ptr->gamma_shift][gray16 >> 8];
3118 rgb_error |= 1;
3119 }
3120
3121 *(dp++) = (png_byte)((w>>8) & 0xff);
3122 *(dp++) = (png_byte)(w & 0xff);
3123
3124 if (have_alpha != 0)
3125 {
3126 *(dp++) = *(sp++);
3127 *(dp++) = *(sp++);
3128 }
3129 }
3130 }
3131 else
3132 #endif
3133 {
3134 png_bytep sp = row;
3135 png_bytep dp = row;
3136 png_uint_32 i;
3137
3138 for (i = 0; i < row_width; i++)
3139 {
3140 png_uint_16 red, green, blue, gray16;
3141 png_byte hi,lo;
3142
3143 hi=*(sp)++; lo=*(sp)++; red = (png_uint_16)((hi << 8) | (lo));
3144 hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo));
3145 hi=*(sp)++; lo=*(sp)++; blue = (png_uint_16)((hi << 8) | (lo));
3146
3147 if (red != green || red != blue)
3148 rgb_error |= 1;
3149
3150 /* From 1.5.5 in the 16-bit case do the accurate conversion even
3151 * in the 'fast' case - this is because this is where the code
3152 * ends up when handling linear 16-bit data.
3153 */
3154 gray16 = (png_uint_16)((rc*red + gc*green + bc*blue + 16384) >>
3155 15);
3156 *(dp++) = (png_byte)((gray16 >> 8) & 0xff);
3157 *(dp++) = (png_byte)(gray16 & 0xff);
3158
3159 if (have_alpha != 0)
3160 {
3161 *(dp++) = *(sp++);
3162 *(dp++) = *(sp++);
3163 }
3164 }
3165 }
3166 }
3167
3168 row_info->channels = (png_byte)(row_info->channels - 2);
3169 row_info->color_type = (png_byte)(row_info->color_type &
3170 ~PNG_COLOR_MASK_COLOR);
3171 row_info->pixel_depth = (png_byte)(row_info->channels *
3172 row_info->bit_depth);
3173 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
3174 }
3175 return rgb_error;
3176 }
3177 #endif
3178
3179 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
3180 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
3181 /* Replace any alpha or transparency with the supplied background color.
3182 * "background" is already in the screen gamma, while "background_1" is
3183 * at a gamma of 1.0. Paletted files have already been taken care of.
3184 */
3185 static void
3186 png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
3187 {
3188 #ifdef PNG_READ_GAMMA_SUPPORTED
3189 png_const_bytep gamma_table = png_ptr->gamma_table;
3190 png_const_bytep gamma_from_1 = png_ptr->gamma_from_1;
3191 png_const_bytep gamma_to_1 = png_ptr->gamma_to_1;
3192 png_const_uint_16pp gamma_16 = png_ptr->gamma_16_table;
3193 png_const_uint_16pp gamma_16_from_1 = png_ptr->gamma_16_from_1;
3194 png_const_uint_16pp gamma_16_to_1 = png_ptr->gamma_16_to_1;
3195 int gamma_shift = png_ptr->gamma_shift;
3196 int optimize = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0;
3197 #endif
3198
3199 png_bytep sp;
3200 png_uint_32 i;
3201 png_uint_32 row_width = row_info->width;
3202 int shift;
3203
3204 png_debug(1, "in png_do_compose");
3205
3206 {
3207 switch (row_info->color_type)
3208 {
3209 case PNG_COLOR_TYPE_GRAY:
3210 {
3211 switch (row_info->bit_depth)
3212 {
3213 case 1:
3214 {
3215 sp = row;
3216 shift = 7;
3217 for (i = 0; i < row_width; i++)
3218 {
3219 if ((png_uint_16)((*sp >> shift) & 0x01)
3220 == png_ptr->trans_color.gray)
3221 {
3222 unsigned int tmp = *sp & (0x7f7f >> (7 - shift));
3223 tmp |= png_ptr->background.gray << shift;
3224 *sp = (png_byte)(tmp & 0xff);
3225 }
3226
3227 if (shift == 0)
3228 {
3229 shift = 7;
3230 sp++;
3231 }
3232
3233 else
3234 shift--;
3235 }
3236 break;
3237 }
3238
3239 case 2:
3240 {
3241 #ifdef PNG_READ_GAMMA_SUPPORTED
3242 if (gamma_table != NULL)
3243 {
3244 sp = row;
3245 shift = 6;
3246 for (i = 0; i < row_width; i++)
3247 {
3248 if ((png_uint_16)((*sp >> shift) & 0x03)
3249 == png_ptr->trans_color.gray)
3250 {
3251 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3252 tmp |= png_ptr->background.gray << shift;
3253 *sp = (png_byte)(tmp & 0xff);
3254 }
3255
3256 else
3257 {
3258 unsigned int p = (*sp >> shift) & 0x03;
3259 unsigned int g = (gamma_table [p | (p << 2) |
3260 (p << 4) | (p << 6)] >> 6) & 0x03;
3261 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3262 tmp |= g << shift;
3263 *sp = (png_byte)(tmp & 0xff);
3264 }
3265
3266 if (shift == 0)
3267 {
3268 shift = 6;
3269 sp++;
3270 }
3271
3272 else
3273 shift -= 2;
3274 }
3275 }
3276
3277 else
3278 #endif
3279 {
3280 sp = row;
3281 shift = 6;
3282 for (i = 0; i < row_width; i++)
3283 {
3284 if ((png_uint_16)((*sp >> shift) & 0x03)
3285 == png_ptr->trans_color.gray)
3286 {
3287 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3288 tmp |= png_ptr->background.gray << shift;
3289 *sp = (png_byte)(tmp & 0xff);
3290 }
3291
3292 if (shift == 0)
3293 {
3294 shift = 6;
3295 sp++;
3296 }
3297
3298 else
3299 shift -= 2;
3300 }
3301 }
3302 break;
3303 }
3304
3305 case 4:
3306 {
3307 #ifdef PNG_READ_GAMMA_SUPPORTED
3308 if (gamma_table != NULL)
3309 {
3310 sp = row;
3311 shift = 4;
3312 for (i = 0; i < row_width; i++)
3313 {
3314 if ((png_uint_16)((*sp >> shift) & 0x0f)
3315 == png_ptr->trans_color.gray)
3316 {
3317 unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
3318 tmp |= png_ptr->background.gray << shift;
3319 *sp = (png_byte)(tmp & 0xff);
3320 }
3321
3322 else
3323 {
3324 unsigned int p = (*sp >> shift) & 0x0f;
3325 unsigned int g = (gamma_table[p | (p << 4)] >> 4) &
3326 0x0f;
3327 unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
3328 tmp |= g << shift;
3329 *sp = (png_byte)(tmp & 0xff);
3330 }
3331
3332 if (shift == 0)
3333 {
3334 shift = 4;
3335 sp++;
3336 }
3337
3338 else
3339 shift -= 4;
3340 }
3341 }
3342
3343 else
3344 #endif
3345 {
3346 sp = row;
3347 shift = 4;
3348 for (i = 0; i < row_width; i++)
3349 {
3350 if ((png_uint_16)((*sp >> shift) & 0x0f)
3351 == png_ptr->trans_color.gray)
3352 {
3353 unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
3354 tmp |= png_ptr->background.gray << shift;
3355 *sp = (png_byte)(tmp & 0xff);
3356 }
3357
3358 if (shift == 0)
3359 {
3360 shift = 4;
3361 sp++;
3362 }
3363
3364 else
3365 shift -= 4;
3366 }
3367 }
3368 break;
3369 }
3370
3371 case 8:
3372 {
3373 #ifdef PNG_READ_GAMMA_SUPPORTED
3374 if (gamma_table != NULL)
3375 {
3376 sp = row;
3377 for (i = 0; i < row_width; i++, sp++)
3378 {
3379 if (*sp == png_ptr->trans_color.gray)
3380 *sp = (png_byte)png_ptr->background.gray;
3381
3382 else
3383 *sp = gamma_table[*sp];
3384 }
3385 }
3386 else
3387 #endif
3388 {
3389 sp = row;
3390 for (i = 0; i < row_width; i++, sp++)
3391 {
3392 if (*sp == png_ptr->trans_color.gray)
3393 *sp = (png_byte)png_ptr->background.gray;
3394 }
3395 }
3396 break;
3397 }
3398
3399 case 16:
3400 {
3401 #ifdef PNG_READ_GAMMA_SUPPORTED
3402 if (gamma_16 != NULL)
3403 {
3404 sp = row;
3405 for (i = 0; i < row_width; i++, sp += 2)
3406 {
3407 png_uint_16 v;
3408
3409 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3410
3411 if (v == png_ptr->trans_color.gray)
3412 {
3413 /* Background is already in screen gamma */
3414 *sp = (png_byte)((png_ptr->background.gray >> 8)
3415 & 0xff);
3416 *(sp + 1) = (png_byte)(png_ptr->background.gray
3417 & 0xff);
3418 }
3419
3420 else
3421 {
3422 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3423 *sp = (png_byte)((v >> 8) & 0xff);
3424 *(sp + 1) = (png_byte)(v & 0xff);
3425 }
3426 }
3427 }
3428 else
3429 #endif
3430 {
3431 sp = row;
3432 for (i = 0; i < row_width; i++, sp += 2)
3433 {
3434 png_uint_16 v;
3435
3436 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3437
3438 if (v == png_ptr->trans_color.gray)
3439 {
3440 *sp = (png_byte)((png_ptr->background.gray >> 8)
3441 & 0xff);
3442 *(sp + 1) = (png_byte)(png_ptr->background.gray
3443 & 0xff);
3444 }
3445 }
3446 }
3447 break;
3448 }
3449
3450 default:
3451 break;
3452 }
3453 break;
3454 }
3455
3456 case PNG_COLOR_TYPE_RGB:
3457 {
3458 if (row_info->bit_depth == 8)
3459 {
3460 #ifdef PNG_READ_GAMMA_SUPPORTED
3461 if (gamma_table != NULL)
3462 {
3463 sp = row;
3464 for (i = 0; i < row_width; i++, sp += 3)
3465 {
3466 if (*sp == png_ptr->trans_color.red &&
3467 *(sp + 1) == png_ptr->trans_color.green &&
3468 *(sp + 2) == png_ptr->trans_color.blue)
3469 {
3470 *sp = (png_byte)png_ptr->background.red;
3471 *(sp + 1) = (png_byte)png_ptr->background.green;
3472 *(sp + 2) = (png_byte)png_ptr->background.blue;
3473 }
3474
3475 else
3476 {
3477 *sp = gamma_table[*sp];
3478 *(sp + 1) = gamma_table[*(sp + 1)];
3479 *(sp + 2) = gamma_table[*(sp + 2)];
3480 }
3481 }
3482 }
3483 else
3484 #endif
3485 {
3486 sp = row;
3487 for (i = 0; i < row_width; i++, sp += 3)
3488 {
3489 if (*sp == png_ptr->trans_color.red &&
3490 *(sp + 1) == png_ptr->trans_color.green &&
3491 *(sp + 2) == png_ptr->trans_color.blue)
3492 {
3493 *sp = (png_byte)png_ptr->background.red;
3494 *(sp + 1) = (png_byte)png_ptr->background.green;
3495 *(sp + 2) = (png_byte)png_ptr->background.blue;
3496 }
3497 }
3498 }
3499 }
3500 else /* if (row_info->bit_depth == 16) */
3501 {
3502 #ifdef PNG_READ_GAMMA_SUPPORTED
3503 if (gamma_16 != NULL)
3504 {
3505 sp = row;
3506 for (i = 0; i < row_width; i++, sp += 6)
3507 {
3508 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3509
3510 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3511 + *(sp + 3));
3512
3513 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3514 + *(sp + 5));
3515
3516 if (r == png_ptr->trans_color.red &&
3517 g == png_ptr->trans_color.green &&
3518 b == png_ptr->trans_color.blue)
3519 {
3520 /* Background is already in screen gamma */
3521 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3522 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3523 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3524 & 0xff);
3525 *(sp + 3) = (png_byte)(png_ptr->background.green
3526 & 0xff);
3527 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3528 & 0xff);
3529 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3530 }
3531
3532 else
3533 {
3534 png_uint_16 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3535 *sp = (png_byte)((v >> 8) & 0xff);
3536 *(sp + 1) = (png_byte)(v & 0xff);
3537
3538 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
3539 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3540 *(sp + 3) = (png_byte)(v & 0xff);
3541
3542 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
3543 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3544 *(sp + 5) = (png_byte)(v & 0xff);
3545 }
3546 }
3547 }
3548
3549 else
3550 #endif
3551 {
3552 sp = row;
3553 for (i = 0; i < row_width; i++, sp += 6)
3554 {
3555 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3556
3557 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3558 + *(sp + 3));
3559
3560 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3561 + *(sp + 5));
3562
3563 if (r == png_ptr->trans_color.red &&
3564 g == png_ptr->trans_color.green &&
3565 b == png_ptr->trans_color.blue)
3566 {
3567 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3568 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3569 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3570 & 0xff);
3571 *(sp + 3) = (png_byte)(png_ptr->background.green
3572 & 0xff);
3573 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3574 & 0xff);
3575 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3576 }
3577 }
3578 }
3579 }
3580 break;
3581 }
3582
3583 case PNG_COLOR_TYPE_GRAY_ALPHA:
3584 {
3585 if (row_info->bit_depth == 8)
3586 {
3587 #ifdef PNG_READ_GAMMA_SUPPORTED
3588 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
3589 gamma_table != NULL)
3590 {
3591 sp = row;
3592 for (i = 0; i < row_width; i++, sp += 2)
3593 {
3594 png_uint_16 a = *(sp + 1);
3595
3596 if (a == 0xff)
3597 *sp = gamma_table[*sp];
3598
3599 else if (a == 0)
3600 {
3601 /* Background is already in screen gamma */
3602 *sp = (png_byte)png_ptr->background.gray;
3603 }
3604
3605 else
3606 {
3607 png_byte v, w;
3608
3609 v = gamma_to_1[*sp];
3610 png_composite(w, v, a, png_ptr->background_1.gray);
3611 if (optimize == 0)
3612 w = gamma_from_1[w];
3613 *sp = w;
3614 }
3615 }
3616 }
3617 else
3618 #endif
3619 {
3620 sp = row;
3621 for (i = 0; i < row_width; i++, sp += 2)
3622 {
3623 png_byte a = *(sp + 1);
3624
3625 if (a == 0)
3626 *sp = (png_byte)png_ptr->background.gray;
3627
3628 else if (a < 0xff)
3629 png_composite(*sp, *sp, a, png_ptr->background.gray);
3630 }
3631 }
3632 }
3633 else /* if (png_ptr->bit_depth == 16) */
3634 {
3635 #ifdef PNG_READ_GAMMA_SUPPORTED
3636 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
3637 gamma_16_to_1 != NULL)
3638 {
3639 sp = row;
3640 for (i = 0; i < row_width; i++, sp += 4)
3641 {
3642 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
3643 + *(sp + 3));
3644
3645 if (a == (png_uint_16)0xffff)
3646 {
3647 png_uint_16 v;
3648
3649 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3650 *sp = (png_byte)((v >> 8) & 0xff);
3651 *(sp + 1) = (png_byte)(v & 0xff);
3652 }
3653
3654 else if (a == 0)
3655 {
3656 /* Background is already in screen gamma */
3657 *sp = (png_byte)((png_ptr->background.gray >> 8)
3658 & 0xff);
3659 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
3660 }
3661
3662 else
3663 {
3664 png_uint_16 g, v, w;
3665
3666 g = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
3667 png_composite_16(v, g, a, png_ptr->background_1.gray);
3668 if (optimize != 0)
3669 w = v;
3670 else
3671 w = gamma_16_from_1[(v & 0xff) >>
3672 gamma_shift][v >> 8];
3673 *sp = (png_byte)((w >> 8) & 0xff);
3674 *(sp + 1) = (png_byte)(w & 0xff);
3675 }
3676 }
3677 }
3678 else
3679 #endif
3680