[LIBPNG] Sync up to 1.6.18. CORE-10071
[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 1.6.18 [July 23, 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 break;
980 }
981
982 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
983 #ifdef PNG_READ_EXPAND_SUPPORTED
984 png_ptr->transformations |= PNG_EXPAND;
985 #else
986 {
987 /* Make this an error in 1.6 because otherwise the application may assume
988 * that it just worked and get a memory overwrite.
989 */
990 png_error(png_ptr,
991 "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED");
992
993 /* png_ptr->transformations &= ~PNG_RGB_TO_GRAY; */
994 }
995 #endif
996 {
997 if (red >= 0 && green >= 0 && red + green <= PNG_FP_1)
998 {
999 png_uint_16 red_int, green_int;
1000
1001 /* NOTE: this calculation does not round, but this behavior is retained
1002 * for consistency; the inaccuracy is very small. The code here always
1003 * overwrites the coefficients, regardless of whether they have been
1004 * defaulted or set already.
1005 */
1006 red_int = (png_uint_16)(((png_uint_32)red*32768)/100000);
1007 green_int = (png_uint_16)(((png_uint_32)green*32768)/100000);
1008
1009 png_ptr->rgb_to_gray_red_coeff = red_int;
1010 png_ptr->rgb_to_gray_green_coeff = green_int;
1011 png_ptr->rgb_to_gray_coefficients_set = 1;
1012 }
1013
1014 else
1015 {
1016 if (red >= 0 && green >= 0)
1017 png_app_warning(png_ptr,
1018 "ignoring out of range rgb_to_gray coefficients");
1019
1020 /* Use the defaults, from the cHRM chunk if set, else the historical
1021 * values which are close to the sRGB/HDTV/ITU-Rec 709 values. See
1022 * png_do_rgb_to_gray for more discussion of the values. In this case
1023 * the coefficients are not marked as 'set' and are not overwritten if
1024 * something has already provided a default.
1025 */
1026 if (png_ptr->rgb_to_gray_red_coeff == 0 &&
1027 png_ptr->rgb_to_gray_green_coeff == 0)
1028 {
1029 png_ptr->rgb_to_gray_red_coeff = 6968;
1030 png_ptr->rgb_to_gray_green_coeff = 23434;
1031 /* png_ptr->rgb_to_gray_blue_coeff = 2366; */
1032 }
1033 }
1034 }
1035 }
1036
1037 #ifdef PNG_FLOATING_POINT_SUPPORTED
1038 /* Convert a RGB image to a grayscale of the same width. This allows us,
1039 * for example, to convert a 24 bpp RGB image into an 8 bpp grayscale image.
1040 */
1041
1042 void PNGAPI
1043 png_set_rgb_to_gray(png_structrp png_ptr, int error_action, double red,
1044 double green)
1045 {
1046 png_set_rgb_to_gray_fixed(png_ptr, error_action,
1047 png_fixed(png_ptr, red, "rgb to gray red coefficient"),
1048 png_fixed(png_ptr, green, "rgb to gray green coefficient"));
1049 }
1050 #endif /* FLOATING POINT */
1051
1052 #endif /* RGB_TO_GRAY */
1053
1054 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
1055 defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
1056 void PNGAPI
1057 png_set_read_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr
1058 read_user_transform_fn)
1059 {
1060 png_debug(1, "in png_set_read_user_transform_fn");
1061
1062 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
1063 png_ptr->transformations |= PNG_USER_TRANSFORM;
1064 png_ptr->read_user_transform_fn = read_user_transform_fn;
1065 #endif
1066 }
1067 #endif
1068
1069 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
1070 #ifdef PNG_READ_GAMMA_SUPPORTED
1071 /* In the case of gamma transformations only do transformations on images where
1072 * the [file] gamma and screen_gamma are not close reciprocals, otherwise it
1073 * slows things down slightly, and also needlessly introduces small errors.
1074 */
1075 static int /* PRIVATE */
1076 png_gamma_threshold(png_fixed_point screen_gamma, png_fixed_point file_gamma)
1077 {
1078 /* PNG_GAMMA_THRESHOLD is the threshold for performing gamma
1079 * correction as a difference of the overall transform from 1.0
1080 *
1081 * We want to compare the threshold with s*f - 1, if we get
1082 * overflow here it is because of wacky gamma values so we
1083 * turn on processing anyway.
1084 */
1085 png_fixed_point gtest;
1086 return !png_muldiv(&gtest, screen_gamma, file_gamma, PNG_FP_1) ||
1087 png_gamma_significant(gtest);
1088 }
1089 #endif
1090
1091 /* Initialize everything needed for the read. This includes modifying
1092 * the palette.
1093 */
1094
1095 /* For the moment 'png_init_palette_transformations' and
1096 * 'png_init_rgb_transformations' only do some flag canceling optimizations.
1097 * The intent is that these two routines should have palette or rgb operations
1098 * extracted from 'png_init_read_transformations'.
1099 */
1100 static void /* PRIVATE */
1101 png_init_palette_transformations(png_structrp png_ptr)
1102 {
1103 /* Called to handle the (input) palette case. In png_do_read_transformations
1104 * the first step is to expand the palette if requested, so this code must
1105 * take care to only make changes that are invariant with respect to the
1106 * palette expansion, or only do them if there is no expansion.
1107 *
1108 * STRIP_ALPHA has already been handled in the caller (by setting num_trans
1109 * to 0.)
1110 */
1111 int input_has_alpha = 0;
1112 int input_has_transparency = 0;
1113
1114 if (png_ptr->num_trans > 0)
1115 {
1116 int i;
1117
1118 /* Ignore if all the entries are opaque (unlikely!) */
1119 for (i=0; i<png_ptr->num_trans; ++i)
1120 {
1121 if (png_ptr->trans_alpha[i] == 255)
1122 continue;
1123 else if (png_ptr->trans_alpha[i] == 0)
1124 input_has_transparency = 1;
1125 else
1126 {
1127 input_has_transparency = 1;
1128 input_has_alpha = 1;
1129 break;
1130 }
1131 }
1132 }
1133
1134 /* If no alpha we can optimize. */
1135 if (input_has_alpha == 0)
1136 {
1137 /* Any alpha means background and associative alpha processing is
1138 * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
1139 * and ENCODE_ALPHA are irrelevant.
1140 */
1141 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1142 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1143
1144 if (input_has_transparency == 0)
1145 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1146 }
1147
1148 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1149 /* png_set_background handling - deals with the complexity of whether the
1150 * background color is in the file format or the screen format in the case
1151 * where an 'expand' will happen.
1152 */
1153
1154 /* The following code cannot be entered in the alpha pre-multiplication case
1155 * because PNG_BACKGROUND_EXPAND is cancelled below.
1156 */
1157 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
1158 (png_ptr->transformations & PNG_EXPAND) != 0)
1159 {
1160 {
1161 png_ptr->background.red =
1162 png_ptr->palette[png_ptr->background.index].red;
1163 png_ptr->background.green =
1164 png_ptr->palette[png_ptr->background.index].green;
1165 png_ptr->background.blue =
1166 png_ptr->palette[png_ptr->background.index].blue;
1167
1168 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1169 if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
1170 {
1171 if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
1172 {
1173 /* Invert the alpha channel (in tRNS) unless the pixels are
1174 * going to be expanded, in which case leave it for later
1175 */
1176 int i, istop = png_ptr->num_trans;
1177
1178 for (i=0; i<istop; i++)
1179 png_ptr->trans_alpha[i] = (png_byte)(255 -
1180 png_ptr->trans_alpha[i]);
1181 }
1182 }
1183 #endif /* READ_INVERT_ALPHA */
1184 }
1185 } /* background expand and (therefore) no alpha association. */
1186 #endif /* READ_EXPAND && READ_BACKGROUND */
1187 }
1188
1189 static void /* PRIVATE */
1190 png_init_rgb_transformations(png_structrp png_ptr)
1191 {
1192 /* Added to libpng-1.5.4: check the color type to determine whether there
1193 * is any alpha or transparency in the image and simply cancel the
1194 * background and alpha mode stuff if there isn't.
1195 */
1196 int input_has_alpha = (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0;
1197 int input_has_transparency = png_ptr->num_trans > 0;
1198
1199 /* If no alpha we can optimize. */
1200 if (input_has_alpha == 0)
1201 {
1202 /* Any alpha means background and associative alpha processing is
1203 * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
1204 * and ENCODE_ALPHA are irrelevant.
1205 */
1206 # ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1207 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1208 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1209 # endif
1210
1211 if (input_has_transparency == 0)
1212 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1213 }
1214
1215 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1216 /* png_set_background handling - deals with the complexity of whether the
1217 * background color is in the file format or the screen format in the case
1218 * where an 'expand' will happen.
1219 */
1220
1221 /* The following code cannot be entered in the alpha pre-multiplication case
1222 * because PNG_BACKGROUND_EXPAND is cancelled below.
1223 */
1224 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
1225 (png_ptr->transformations & PNG_EXPAND) != 0 &&
1226 (png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
1227 /* i.e., GRAY or GRAY_ALPHA */
1228 {
1229 {
1230 /* Expand background and tRNS chunks */
1231 int gray = png_ptr->background.gray;
1232 int trans_gray = png_ptr->trans_color.gray;
1233
1234 switch (png_ptr->bit_depth)
1235 {
1236 case 1:
1237 gray *= 0xff;
1238 trans_gray *= 0xff;
1239 break;
1240
1241 case 2:
1242 gray *= 0x55;
1243 trans_gray *= 0x55;
1244 break;
1245
1246 case 4:
1247 gray *= 0x11;
1248 trans_gray *= 0x11;
1249 break;
1250
1251 default:
1252
1253 case 8:
1254 /* FALL THROUGH (Already 8 bits) */
1255
1256 case 16:
1257 /* Already a full 16 bits */
1258 break;
1259 }
1260
1261 png_ptr->background.red = png_ptr->background.green =
1262 png_ptr->background.blue = (png_uint_16)gray;
1263
1264 if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
1265 {
1266 png_ptr->trans_color.red = png_ptr->trans_color.green =
1267 png_ptr->trans_color.blue = (png_uint_16)trans_gray;
1268 }
1269 }
1270 } /* background expand and (therefore) no alpha association. */
1271 #endif /* READ_EXPAND && READ_BACKGROUND */
1272 }
1273
1274 void /* PRIVATE */
1275 png_init_read_transformations(png_structrp png_ptr)
1276 {
1277 png_debug(1, "in png_init_read_transformations");
1278
1279 /* This internal function is called from png_read_start_row in pngrutil.c
1280 * and it is called before the 'rowbytes' calculation is done, so the code
1281 * in here can change or update the transformations flags.
1282 *
1283 * First do updates that do not depend on the details of the PNG image data
1284 * being processed.
1285 */
1286
1287 #ifdef PNG_READ_GAMMA_SUPPORTED
1288 /* Prior to 1.5.4 these tests were performed from png_set_gamma, 1.5.4 adds
1289 * png_set_alpha_mode and this is another source for a default file gamma so
1290 * the test needs to be performed later - here. In addition prior to 1.5.4
1291 * the tests were repeated for the PALETTE color type here - this is no
1292 * longer necessary (and doesn't seem to have been necessary before.)
1293 */
1294 {
1295 /* The following temporary indicates if overall gamma correction is
1296 * required.
1297 */
1298 int gamma_correction = 0;
1299
1300 if (png_ptr->colorspace.gamma != 0) /* has been set */
1301 {
1302 if (png_ptr->screen_gamma != 0) /* screen set too */
1303 gamma_correction = png_gamma_threshold(png_ptr->colorspace.gamma,
1304 png_ptr->screen_gamma);
1305
1306 else
1307 /* Assume the output matches the input; a long time default behavior
1308 * of libpng, although the standard has nothing to say about this.
1309 */
1310 png_ptr->screen_gamma = png_reciprocal(png_ptr->colorspace.gamma);
1311 }
1312
1313 else if (png_ptr->screen_gamma != 0)
1314 /* The converse - assume the file matches the screen, note that this
1315 * perhaps undesireable default can (from 1.5.4) be changed by calling
1316 * png_set_alpha_mode (even if the alpha handling mode isn't required
1317 * or isn't changed from the default.)
1318 */
1319 png_ptr->colorspace.gamma = png_reciprocal(png_ptr->screen_gamma);
1320
1321 else /* neither are set */
1322 /* Just in case the following prevents any processing - file and screen
1323 * are both assumed to be linear and there is no way to introduce a
1324 * third gamma value other than png_set_background with 'UNIQUE', and,
1325 * prior to 1.5.4
1326 */
1327 png_ptr->screen_gamma = png_ptr->colorspace.gamma = PNG_FP_1;
1328
1329 /* We have a gamma value now. */
1330 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
1331
1332 /* Now turn the gamma transformation on or off as appropriate. Notice
1333 * that PNG_GAMMA just refers to the file->screen correction. Alpha
1334 * composition may independently cause gamma correction because it needs
1335 * linear data (e.g. if the file has a gAMA chunk but the screen gamma
1336 * hasn't been specified.) In any case this flag may get turned off in
1337 * the code immediately below if the transform can be handled outside the
1338 * row loop.
1339 */
1340 if (gamma_correction != 0)
1341 png_ptr->transformations |= PNG_GAMMA;
1342
1343 else
1344 png_ptr->transformations &= ~PNG_GAMMA;
1345 }
1346 #endif
1347
1348 /* Certain transformations have the effect of preventing other
1349 * transformations that happen afterward in png_do_read_transformations;
1350 * resolve the interdependencies here. From the code of
1351 * png_do_read_transformations the order is:
1352 *
1353 * 1) PNG_EXPAND (including PNG_EXPAND_tRNS)
1354 * 2) PNG_STRIP_ALPHA (if no compose)
1355 * 3) PNG_RGB_TO_GRAY
1356 * 4) PNG_GRAY_TO_RGB iff !PNG_BACKGROUND_IS_GRAY
1357 * 5) PNG_COMPOSE
1358 * 6) PNG_GAMMA
1359 * 7) PNG_STRIP_ALPHA (if compose)
1360 * 8) PNG_ENCODE_ALPHA
1361 * 9) PNG_SCALE_16_TO_8
1362 * 10) PNG_16_TO_8
1363 * 11) PNG_QUANTIZE (converts to palette)
1364 * 12) PNG_EXPAND_16
1365 * 13) PNG_GRAY_TO_RGB iff PNG_BACKGROUND_IS_GRAY
1366 * 14) PNG_INVERT_MONO
1367 * 15) PNG_INVERT_ALPHA
1368 * 16) PNG_SHIFT
1369 * 17) PNG_PACK
1370 * 18) PNG_BGR
1371 * 19) PNG_PACKSWAP
1372 * 20) PNG_FILLER (includes PNG_ADD_ALPHA)
1373 * 21) PNG_SWAP_ALPHA
1374 * 22) PNG_SWAP_BYTES
1375 * 23) PNG_USER_TRANSFORM [must be last]
1376 */
1377 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1378 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
1379 (png_ptr->transformations & PNG_COMPOSE) == 0)
1380 {
1381 /* Stripping the alpha channel happens immediately after the 'expand'
1382 * transformations, before all other transformation, so it cancels out
1383 * the alpha handling. It has the side effect negating the effect of
1384 * PNG_EXPAND_tRNS too:
1385 */
1386 png_ptr->transformations &= ~(PNG_BACKGROUND_EXPAND | PNG_ENCODE_ALPHA |
1387 PNG_EXPAND_tRNS);
1388 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1389
1390 /* Kill the tRNS chunk itself too. Prior to 1.5.4 this did not happen
1391 * so transparency information would remain just so long as it wasn't
1392 * expanded. This produces unexpected API changes if the set of things
1393 * that do PNG_EXPAND_tRNS changes (perfectly possible given the
1394 * documentation - which says ask for what you want, accept what you
1395 * get.) This makes the behavior consistent from 1.5.4:
1396 */
1397 png_ptr->num_trans = 0;
1398 }
1399 #endif /* STRIP_ALPHA supported, no COMPOSE */
1400
1401 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1402 /* If the screen gamma is about 1.0 then the OPTIMIZE_ALPHA and ENCODE_ALPHA
1403 * settings will have no effect.
1404 */
1405 if (png_gamma_significant(png_ptr->screen_gamma) == 0)
1406 {
1407 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1408 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1409 }
1410 #endif
1411
1412 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1413 /* Make sure the coefficients for the rgb to gray conversion are set
1414 * appropriately.
1415 */
1416 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
1417 png_colorspace_set_rgb_coefficients(png_ptr);
1418 #endif
1419
1420 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1421 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1422 /* Detect gray background and attempt to enable optimization for
1423 * gray --> RGB case.
1424 *
1425 * Note: if PNG_BACKGROUND_EXPAND is set and color_type is either RGB or
1426 * RGB_ALPHA (in which case need_expand is superfluous anyway), the
1427 * background color might actually be gray yet not be flagged as such.
1428 * This is not a problem for the current code, which uses
1429 * PNG_BACKGROUND_IS_GRAY only to decide when to do the
1430 * png_do_gray_to_rgb() transformation.
1431 *
1432 * TODO: this code needs to be revised to avoid the complexity and
1433 * interdependencies. The color type of the background should be recorded in
1434 * png_set_background, along with the bit depth, then the code has a record
1435 * of exactly what color space the background is currently in.
1436 */
1437 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0)
1438 {
1439 /* PNG_BACKGROUND_EXPAND: the background is in the file color space, so if
1440 * the file was grayscale the background value is gray.
1441 */
1442 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
1443 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1444 }
1445
1446 else if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1447 {
1448 /* PNG_COMPOSE: png_set_background was called with need_expand false,
1449 * so the color is in the color space of the output or png_set_alpha_mode
1450 * was called and the color is black. Ignore RGB_TO_GRAY because that
1451 * happens before GRAY_TO_RGB.
1452 */
1453 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
1454 {
1455 if (png_ptr->background.red == png_ptr->background.green &&
1456 png_ptr->background.red == png_ptr->background.blue)
1457 {
1458 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1459 png_ptr->background.gray = png_ptr->background.red;
1460 }
1461 }
1462 }
1463 #endif /* READ_EXPAND && READ_BACKGROUND */
1464 #endif /* READ_GRAY_TO_RGB */
1465
1466 /* For indexed PNG data (PNG_COLOR_TYPE_PALETTE) many of the transformations
1467 * can be performed directly on the palette, and some (such as rgb to gray)
1468 * can be optimized inside the palette. This is particularly true of the
1469 * composite (background and alpha) stuff, which can be pretty much all done
1470 * in the palette even if the result is expanded to RGB or gray afterward.
1471 *
1472 * NOTE: this is Not Yet Implemented, the code behaves as in 1.5.1 and
1473 * earlier and the palette stuff is actually handled on the first row. This
1474 * leads to the reported bug that the palette returned by png_get_PLTE is not
1475 * updated.
1476 */
1477 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1478 png_init_palette_transformations(png_ptr);
1479
1480 else
1481 png_init_rgb_transformations(png_ptr);
1482
1483 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1484 defined(PNG_READ_EXPAND_16_SUPPORTED)
1485 if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
1486 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
1487 (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
1488 png_ptr->bit_depth != 16)
1489 {
1490 /* TODO: fix this. Because the expand_16 operation is after the compose
1491 * handling the background color must be 8, not 16, bits deep, but the
1492 * application will supply a 16-bit value so reduce it here.
1493 *
1494 * The PNG_BACKGROUND_EXPAND code above does not expand to 16 bits at
1495 * present, so that case is ok (until do_expand_16 is moved.)
1496 *
1497 * NOTE: this discards the low 16 bits of the user supplied background
1498 * color, but until expand_16 works properly there is no choice!
1499 */
1500 # define CHOP(x) (x)=((png_uint_16)PNG_DIV257(x))
1501 CHOP(png_ptr->background.red);
1502 CHOP(png_ptr->background.green);
1503 CHOP(png_ptr->background.blue);
1504 CHOP(png_ptr->background.gray);
1505 # undef CHOP
1506 }
1507 #endif /* READ_BACKGROUND && READ_EXPAND_16 */
1508
1509 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1510 (defined(PNG_READ_SCALE_16_TO_8_SUPPORTED) || \
1511 defined(PNG_READ_STRIP_16_TO_8_SUPPORTED))
1512 if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) != 0 &&
1513 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
1514 (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
1515 png_ptr->bit_depth == 16)
1516 {
1517 /* On the other hand, if a 16-bit file is to be reduced to 8-bits per
1518 * component this will also happen after PNG_COMPOSE and so the background
1519 * color must be pre-expanded here.
1520 *
1521 * TODO: fix this too.
1522 */
1523 png_ptr->background.red = (png_uint_16)(png_ptr->background.red * 257);
1524 png_ptr->background.green =
1525 (png_uint_16)(png_ptr->background.green * 257);
1526 png_ptr->background.blue = (png_uint_16)(png_ptr->background.blue * 257);
1527 png_ptr->background.gray = (png_uint_16)(png_ptr->background.gray * 257);
1528 }
1529 #endif
1530
1531 /* NOTE: below 'PNG_READ_ALPHA_MODE_SUPPORTED' is presumed to also enable the
1532 * background support (see the comments in scripts/pnglibconf.dfa), this
1533 * allows pre-multiplication of the alpha channel to be implemented as
1534 * compositing on black. This is probably sub-optimal and has been done in
1535 * 1.5.4 betas simply to enable external critique and testing (i.e. to
1536 * implement the new API quickly, without lots of internal changes.)
1537 */
1538
1539 #ifdef PNG_READ_GAMMA_SUPPORTED
1540 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1541 /* Includes ALPHA_MODE */
1542 png_ptr->background_1 = png_ptr->background;
1543 # endif
1544
1545 /* This needs to change - in the palette image case a whole set of tables are
1546 * built when it would be quicker to just calculate the correct value for
1547 * each palette entry directly. Also, the test is too tricky - why check
1548 * PNG_RGB_TO_GRAY if PNG_GAMMA is not set? The answer seems to be that
1549 * PNG_GAMMA is cancelled even if the gamma is known? The test excludes the
1550 * PNG_COMPOSE case, so apparently if there is no *overall* gamma correction
1551 * the gamma tables will not be built even if composition is required on a
1552 * gamma encoded value.
1553 *
1554 * In 1.5.4 this is addressed below by an additional check on the individual
1555 * file gamma - if it is not 1.0 both RGB_TO_GRAY and COMPOSE need the
1556 * tables.
1557 */
1558 if ((png_ptr->transformations & PNG_GAMMA) != 0 ||
1559 ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0 &&
1560 (png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
1561 png_gamma_significant(png_ptr->screen_gamma) != 0)) ||
1562 ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
1563 (png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
1564 png_gamma_significant(png_ptr->screen_gamma) != 0
1565 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1566 || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE &&
1567 png_gamma_significant(png_ptr->background_gamma) != 0)
1568 # endif
1569 )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 &&
1570 png_gamma_significant(png_ptr->screen_gamma) != 0))
1571 {
1572 png_build_gamma_table(png_ptr, png_ptr->bit_depth);
1573
1574 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1575 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1576 {
1577 /* Issue a warning about this combination: because RGB_TO_GRAY is
1578 * optimized to do the gamma transform if present yet do_background has
1579 * to do the same thing if both options are set a
1580 * double-gamma-correction happens. This is true in all versions of
1581 * libpng to date.
1582 */
1583 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
1584 png_warning(png_ptr,
1585 "libpng does not support gamma+background+rgb_to_gray");
1586
1587 if ((png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) != 0)
1588 {
1589 /* We don't get to here unless there is a tRNS chunk with non-opaque
1590 * entries - see the checking code at the start of this function.
1591 */
1592 png_color back, back_1;
1593 png_colorp palette = png_ptr->palette;
1594 int num_palette = png_ptr->num_palette;
1595 int i;
1596 if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_FILE)
1597 {
1598
1599 back.red = png_ptr->gamma_table[png_ptr->background.red];
1600 back.green = png_ptr->gamma_table[png_ptr->background.green];
1601 back.blue = png_ptr->gamma_table[png_ptr->background.blue];
1602
1603 back_1.red = png_ptr->gamma_to_1[png_ptr->background.red];
1604 back_1.green = png_ptr->gamma_to_1[png_ptr->background.green];
1605 back_1.blue = png_ptr->gamma_to_1[png_ptr->background.blue];
1606 }
1607 else
1608 {
1609 png_fixed_point g, gs;
1610
1611 switch (png_ptr->background_gamma_type)
1612 {
1613 case PNG_BACKGROUND_GAMMA_SCREEN:
1614 g = (png_ptr->screen_gamma);
1615 gs = PNG_FP_1;
1616 break;
1617
1618 case PNG_BACKGROUND_GAMMA_FILE:
1619 g = png_reciprocal(png_ptr->colorspace.gamma);
1620 gs = png_reciprocal2(png_ptr->colorspace.gamma,
1621 png_ptr->screen_gamma);
1622 break;
1623
1624 case PNG_BACKGROUND_GAMMA_UNIQUE:
1625 g = png_reciprocal(png_ptr->background_gamma);
1626 gs = png_reciprocal2(png_ptr->background_gamma,
1627 png_ptr->screen_gamma);
1628 break;
1629 default:
1630 g = PNG_FP_1; /* back_1 */
1631 gs = PNG_FP_1; /* back */
1632 break;
1633 }
1634
1635 if (png_gamma_significant(gs) != 0)
1636 {
1637 back.red = png_gamma_8bit_correct(png_ptr->background.red,
1638 gs);
1639 back.green = png_gamma_8bit_correct(png_ptr->background.green,
1640 gs);
1641 back.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1642 gs);
1643 }
1644
1645 else
1646 {
1647 back.red = (png_byte)png_ptr->background.red;
1648 back.green = (png_byte)png_ptr->background.green;
1649 back.blue = (png_byte)png_ptr->background.blue;
1650 }
1651
1652 if (png_gamma_significant(g) != 0)
1653 {
1654 back_1.red = png_gamma_8bit_correct(png_ptr->background.red,
1655 g);
1656 back_1.green = png_gamma_8bit_correct(
1657 png_ptr->background.green, g);
1658 back_1.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1659 g);
1660 }
1661
1662 else
1663 {
1664 back_1.red = (png_byte)png_ptr->background.red;
1665 back_1.green = (png_byte)png_ptr->background.green;
1666 back_1.blue = (png_byte)png_ptr->background.blue;
1667 }
1668 }
1669
1670 for (i = 0; i < num_palette; i++)
1671 {
1672 if (i < (int)png_ptr->num_trans &&
1673 png_ptr->trans_alpha[i] != 0xff)
1674 {
1675 if (png_ptr->trans_alpha[i] == 0)
1676 {
1677 palette[i] = back;
1678 }
1679 else /* if (png_ptr->trans_alpha[i] != 0xff) */
1680 {
1681 png_byte v, w;
1682
1683 v = png_ptr->gamma_to_1[palette[i].red];
1684 png_composite(w, v, png_ptr->trans_alpha[i], back_1.red);
1685 palette[i].red = png_ptr->gamma_from_1[w];
1686
1687 v = png_ptr->gamma_to_1[palette[i].green];
1688 png_composite(w, v, png_ptr->trans_alpha[i], back_1.green);
1689 palette[i].green = png_ptr->gamma_from_1[w];
1690
1691 v = png_ptr->gamma_to_1[palette[i].blue];
1692 png_composite(w, v, png_ptr->trans_alpha[i], back_1.blue);
1693 palette[i].blue = png_ptr->gamma_from_1[w];
1694 }
1695 }
1696 else
1697 {
1698 palette[i].red = png_ptr->gamma_table[palette[i].red];
1699 palette[i].green = png_ptr->gamma_table[palette[i].green];
1700 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1701 }
1702 }
1703
1704 /* Prevent the transformations being done again.
1705 *
1706 * NOTE: this is highly dubious; it removes the transformations in
1707 * place. This seems inconsistent with the general treatment of the
1708 * transformations elsewhere.
1709 */
1710 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_GAMMA);
1711 } /* color_type == PNG_COLOR_TYPE_PALETTE */
1712
1713 /* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */
1714 else /* color_type != PNG_COLOR_TYPE_PALETTE */
1715 {
1716 int gs_sig, g_sig;
1717 png_fixed_point g = PNG_FP_1; /* Correction to linear */
1718 png_fixed_point gs = PNG_FP_1; /* Correction to screen */
1719
1720 switch (png_ptr->background_gamma_type)
1721 {
1722 case PNG_BACKGROUND_GAMMA_SCREEN:
1723 g = png_ptr->screen_gamma;
1724 /* gs = PNG_FP_1; */
1725 break;
1726
1727 case PNG_BACKGROUND_GAMMA_FILE:
1728 g = png_reciprocal(png_ptr->colorspace.gamma);
1729 gs = png_reciprocal2(png_ptr->colorspace.gamma,
1730 png_ptr->screen_gamma);
1731 break;
1732
1733 case PNG_BACKGROUND_GAMMA_UNIQUE:
1734 g = png_reciprocal(png_ptr->background_gamma);
1735 gs = png_reciprocal2(png_ptr->background_gamma,
1736 png_ptr->screen_gamma);
1737 break;
1738
1739 default:
1740 png_error(png_ptr, "invalid background gamma type");
1741 }
1742
1743 g_sig = png_gamma_significant(g);
1744 gs_sig = png_gamma_significant(gs);
1745
1746 if (g_sig != 0)
1747 png_ptr->background_1.gray = png_gamma_correct(png_ptr,
1748 png_ptr->background.gray, g);
1749
1750 if (gs_sig != 0)
1751 png_ptr->background.gray = png_gamma_correct(png_ptr,
1752 png_ptr->background.gray, gs);
1753
1754 if ((png_ptr->background.red != png_ptr->background.green) ||
1755 (png_ptr->background.red != png_ptr->background.blue) ||
1756 (png_ptr->background.red != png_ptr->background.gray))
1757 {
1758 /* RGB or RGBA with color background */
1759 if (g_sig != 0)
1760 {
1761 png_ptr->background_1.red = png_gamma_correct(png_ptr,
1762 png_ptr->background.red, g);
1763
1764 png_ptr->background_1.green = png_gamma_correct(png_ptr,
1765 png_ptr->background.green, g);
1766
1767 png_ptr->background_1.blue = png_gamma_correct(png_ptr,
1768 png_ptr->background.blue, g);
1769 }
1770
1771 if (gs_sig != 0)
1772 {
1773 png_ptr->background.red = png_gamma_correct(png_ptr,
1774 png_ptr->background.red, gs);
1775
1776 png_ptr->background.green = png_gamma_correct(png_ptr,
1777 png_ptr->background.green, gs);
1778
1779 png_ptr->background.blue = png_gamma_correct(png_ptr,
1780 png_ptr->background.blue, gs);
1781 }
1782 }
1783
1784 else
1785 {
1786 /* GRAY, GRAY ALPHA, RGB, or RGBA with gray background */
1787 png_ptr->background_1.red = png_ptr->background_1.green
1788 = png_ptr->background_1.blue = png_ptr->background_1.gray;
1789
1790 png_ptr->background.red = png_ptr->background.green
1791 = png_ptr->background.blue = png_ptr->background.gray;
1792 }
1793
1794 /* The background is now in screen gamma: */
1795 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_SCREEN;
1796 } /* color_type != PNG_COLOR_TYPE_PALETTE */
1797 }/* png_ptr->transformations & PNG_BACKGROUND */
1798
1799 else
1800 /* Transformation does not include PNG_BACKGROUND */
1801 #endif /* READ_BACKGROUND */
1802 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE
1803 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1804 /* RGB_TO_GRAY needs to have non-gamma-corrected values! */
1805 && ((png_ptr->transformations & PNG_EXPAND) == 0 ||
1806 (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
1807 #endif
1808 )
1809 {
1810 png_colorp palette = png_ptr->palette;
1811 int num_palette = png_ptr->num_palette;
1812 int i;
1813
1814 /* NOTE: there are other transformations that should probably be in
1815 * here too.
1816 */
1817 for (i = 0; i < num_palette; i++)
1818 {
1819 palette[i].red = png_ptr->gamma_table[palette[i].red];
1820 palette[i].green = png_ptr->gamma_table[palette[i].green];
1821 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1822 }
1823
1824 /* Done the gamma correction. */
1825 png_ptr->transformations &= ~PNG_GAMMA;
1826 } /* color_type == PALETTE && !PNG_BACKGROUND transformation */
1827 }
1828 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1829 else
1830 #endif
1831 #endif /* READ_GAMMA */
1832
1833 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1834 /* No GAMMA transformation (see the hanging else 4 lines above) */
1835 if ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
1836 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1837 {
1838 int i;
1839 int istop = (int)png_ptr->num_trans;
1840 png_color back;
1841 png_colorp palette = png_ptr->palette;
1842
1843 back.red = (png_byte)png_ptr->background.red;
1844 back.green = (png_byte)png_ptr->background.green;
1845 back.blue = (png_byte)png_ptr->background.blue;
1846
1847 for (i = 0; i < istop; i++)
1848 {
1849 if (png_ptr->trans_alpha[i] == 0)
1850 {
1851 palette[i] = back;
1852 }
1853
1854 else if (png_ptr->trans_alpha[i] != 0xff)
1855 {
1856 /* The png_composite() macro is defined in png.h */
1857 png_composite(palette[i].red, palette[i].red,
1858 png_ptr->trans_alpha[i], back.red);
1859
1860 png_composite(palette[i].green, palette[i].green,
1861 png_ptr->trans_alpha[i], back.green);
1862
1863 png_composite(palette[i].blue, palette[i].blue,
1864 png_ptr->trans_alpha[i], back.blue);
1865 }
1866 }
1867
1868 png_ptr->transformations &= ~PNG_COMPOSE;
1869 }
1870 #endif /* READ_BACKGROUND */
1871
1872 #ifdef PNG_READ_SHIFT_SUPPORTED
1873 if ((png_ptr->transformations & PNG_SHIFT) != 0 &&
1874 (png_ptr->transformations & PNG_EXPAND) == 0 &&
1875 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1876 {
1877 int i;
1878 int istop = png_ptr->num_palette;
1879 int shift = 8 - png_ptr->sig_bit.red;
1880
1881 png_ptr->transformations &= ~PNG_SHIFT;
1882
1883 /* significant bits can be in the range 1 to 7 for a meaninful result, if
1884 * the number of significant bits is 0 then no shift is done (this is an
1885 * error condition which is silently ignored.)
1886 */
1887 if (shift > 0 && shift < 8)
1888 for (i=0; i<istop; ++i)
1889 {
1890 int component = png_ptr->palette[i].red;
1891
1892 component >>= shift;
1893 png_ptr->palette[i].red = (png_byte)component;
1894 }
1895
1896 shift = 8 - png_ptr->sig_bit.green;
1897 if (shift > 0 && shift < 8)
1898 for (i=0; i<istop; ++i)
1899 {
1900 int component = png_ptr->palette[i].green;
1901
1902 component >>= shift;
1903 png_ptr->palette[i].green = (png_byte)component;
1904 }
1905
1906 shift = 8 - png_ptr->sig_bit.blue;
1907 if (shift > 0 && shift < 8)
1908 for (i=0; i<istop; ++i)
1909 {
1910 int component = png_ptr->palette[i].blue;
1911
1912 component >>= shift;
1913 png_ptr->palette[i].blue = (png_byte)component;
1914 }
1915 }
1916 #endif /* READ_SHIFT */
1917 }
1918
1919 /* Modify the info structure to reflect the transformations. The
1920 * info should be updated so a PNG file could be written with it,
1921 * assuming the transformations result in valid PNG data.
1922 */
1923 void /* PRIVATE */
1924 png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
1925 {
1926 png_debug(1, "in png_read_transform_info");
1927
1928 #ifdef PNG_READ_EXPAND_SUPPORTED
1929 if ((png_ptr->transformations & PNG_EXPAND) != 0)
1930 {
1931 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1932 {
1933 /* This check must match what actually happens in
1934 * png_do_expand_palette; if it ever checks the tRNS chunk to see if
1935 * it is all opaque we must do the same (at present it does not.)
1936 */
1937 if (png_ptr->num_trans > 0)
1938 info_ptr->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
1939
1940 else
1941 info_ptr->color_type = PNG_COLOR_TYPE_RGB;
1942
1943 info_ptr->bit_depth = 8;
1944 info_ptr->num_trans = 0;
1945
1946 if (png_ptr->palette == NULL)
1947 png_error (png_ptr, "Palette is NULL in indexed image");
1948 }
1949 else
1950 {
1951 if (png_ptr->num_trans != 0)
1952 {
1953 if ((png_ptr->transformations & PNG_EXPAND_tRNS) != 0)
1954 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
1955 }
1956 if (info_ptr->bit_depth < 8)
1957 info_ptr->bit_depth = 8;
1958
1959 info_ptr->num_trans = 0;
1960 }
1961 }
1962 #endif
1963
1964 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
1965 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
1966 /* The following is almost certainly wrong unless the background value is in
1967 * the screen space!
1968 */
1969 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1970 info_ptr->background = png_ptr->background;
1971 #endif
1972
1973 #ifdef PNG_READ_GAMMA_SUPPORTED
1974 /* The following used to be conditional on PNG_GAMMA (prior to 1.5.4),
1975 * however it seems that the code in png_init_read_transformations, which has
1976 * been called before this from png_read_update_info->png_read_start_row
1977 * sometimes does the gamma transform and cancels the flag.
1978 *
1979 * TODO: this looks wrong; the info_ptr should end up with a gamma equal to
1980 * the screen_gamma value. The following probably results in weirdness if
1981 * the info_ptr is used by the app after the rows have been read.
1982 */
1983 info_ptr->colorspace.gamma = png_ptr->colorspace.gamma;
1984 #endif
1985
1986 if (info_ptr->bit_depth == 16)
1987 {
1988 # ifdef PNG_READ_16BIT_SUPPORTED
1989 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1990 if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0)
1991 info_ptr->bit_depth = 8;
1992 # endif
1993
1994 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1995 if ((png_ptr->transformations & PNG_16_TO_8) != 0)
1996 info_ptr->bit_depth = 8;
1997 # endif
1998
1999 # else
2000 /* No 16 bit support: force chopping 16-bit input down to 8, in this case
2001 * the app program can chose if both APIs are available by setting the
2002 * correct scaling to use.
2003 */
2004 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2005 /* For compatibility with previous versions use the strip method by
2006 * default. This code works because if PNG_SCALE_16_TO_8 is already
2007 * set the code below will do that in preference to the chop.
2008 */
2009 png_ptr->transformations |= PNG_16_TO_8;
2010 info_ptr->bit_depth = 8;
2011 # else
2012
2013 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2014 png_ptr->transformations |= PNG_SCALE_16_TO_8;
2015 info_ptr->bit_depth = 8;
2016 # else
2017
2018 CONFIGURATION ERROR: you must enable at least one 16 to 8 method
2019 # endif
2020 # endif
2021 #endif /* !READ_16BIT */
2022 }
2023
2024 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2025 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
2026 info_ptr->color_type = (png_byte)(info_ptr->color_type |
2027 PNG_COLOR_MASK_COLOR);
2028 #endif
2029
2030 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2031 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
2032 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2033 ~PNG_COLOR_MASK_COLOR);
2034 #endif
2035
2036 #ifdef PNG_READ_QUANTIZE_SUPPORTED
2037 if ((png_ptr->transformations & PNG_QUANTIZE) != 0)
2038 {
2039 if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
2040 (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) &&
2041 png_ptr->palette_lookup != 0 && info_ptr->bit_depth == 8)
2042 {
2043 info_ptr->color_type = PNG_COLOR_TYPE_PALETTE;
2044 }
2045 }
2046 #endif
2047
2048 #ifdef PNG_READ_EXPAND_16_SUPPORTED
2049 if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
2050 info_ptr->bit_depth == 8 &&
2051 info_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
2052 {
2053 info_ptr->bit_depth = 16;
2054 }
2055 #endif
2056
2057 #ifdef PNG_READ_PACK_SUPPORTED
2058 if ((png_ptr->transformations & PNG_PACK) != 0 &&
2059 (info_ptr->bit_depth < 8))
2060 info_ptr->bit_depth = 8;
2061 #endif
2062
2063 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
2064 info_ptr->channels = 1;
2065
2066 else if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
2067 info_ptr->channels = 3;
2068
2069 else
2070 info_ptr->channels = 1;
2071
2072 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
2073 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0)
2074 {
2075 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2076 ~PNG_COLOR_MASK_ALPHA);
2077 info_ptr->num_trans = 0;
2078 }
2079 #endif
2080
2081 if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
2082 info_ptr->channels++;
2083
2084 #ifdef PNG_READ_FILLER_SUPPORTED
2085 /* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */
2086 if ((png_ptr->transformations & PNG_FILLER) != 0 &&
2087 (info_ptr->color_type == PNG_COLOR_TYPE_RGB ||
2088 info_ptr->color_type == PNG_COLOR_TYPE_GRAY))
2089 {
2090 info_ptr->channels++;
2091 /* If adding a true alpha channel not just filler */
2092 if ((png_ptr->transformations & PNG_ADD_ALPHA) != 0)
2093 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
2094 }
2095 #endif
2096
2097 #if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \
2098 defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
2099 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
2100 {
2101 if (info_ptr->bit_depth < png_ptr->user_transform_depth)
2102 info_ptr->bit_depth = png_ptr->user_transform_depth;
2103
2104 if (info_ptr->channels < png_ptr->user_transform_channels)
2105 info_ptr->channels = png_ptr->user_transform_channels;
2106 }
2107 #endif
2108
2109 info_ptr->pixel_depth = (png_byte)(info_ptr->channels *
2110 info_ptr->bit_depth);
2111
2112 info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, info_ptr->width);
2113
2114 /* Adding in 1.5.4: cache the above value in png_struct so that we can later
2115 * check in png_rowbytes that the user buffer won't get overwritten. Note
2116 * that the field is not always set - if png_read_update_info isn't called
2117 * the application has to either not do any transforms or get the calculation
2118 * right itself.
2119 */
2120 png_ptr->info_rowbytes = info_ptr->rowbytes;
2121
2122 #ifndef PNG_READ_EXPAND_SUPPORTED
2123 if (png_ptr != NULL)
2124 return;
2125 #endif
2126 }
2127
2128 #ifdef PNG_READ_PACK_SUPPORTED
2129 /* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
2130 * without changing the actual values. Thus, if you had a row with
2131 * a bit depth of 1, you would end up with bytes that only contained
2132 * the numbers 0 or 1. If you would rather they contain 0 and 255, use
2133 * png_do_shift() after this.
2134 */
2135 static void
2136 png_do_unpack(png_row_infop row_info, png_bytep row)
2137 {
2138 png_debug(1, "in png_do_unpack");
2139
2140 if (row_info->bit_depth < 8)
2141 {
2142 png_uint_32 i;
2143 png_uint_32 row_width=row_info->width;
2144
2145 switch (row_info->bit_depth)
2146 {
2147 case 1:
2148 {
2149 png_bytep sp = row + (png_size_t)((row_width - 1) >> 3);
2150 png_bytep dp = row + (png_size_t)row_width - 1;
2151 png_uint_32 shift = 7 - (int)((row_width + 7) & 0x07);
2152 for (i = 0; i < row_width; i++)
2153 {
2154 *dp = (png_byte)((*sp >> shift) & 0x01);
2155
2156 if (shift == 7)
2157 {
2158 shift = 0;
2159 sp--;
2160 }
2161
2162 else
2163 shift++;
2164
2165 dp--;
2166 }
2167 break;
2168 }
2169
2170 case 2:
2171 {
2172
2173 png_bytep sp = row + (png_size_t)((row_width - 1) >> 2);
2174 png_bytep dp = row + (png_size_t)row_width - 1;
2175 png_uint_32 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
2176 for (i = 0; i < row_width; i++)
2177 {
2178 *dp = (png_byte)((*sp >> shift) & 0x03);
2179
2180 if (shift == 6)
2181 {
2182 shift = 0;
2183 sp--;
2184 }
2185
2186 else
2187 shift += 2;
2188
2189 dp--;
2190 }
2191 break;
2192 }
2193
2194 case 4:
2195 {
2196 png_bytep sp = row + (png_size_t)((row_width - 1) >> 1);
2197 png_bytep dp = row + (png_size_t)row_width - 1;
2198 png_uint_32 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
2199 for (i = 0; i < row_width; i++)
2200 {
2201 *dp = (png_byte)((*sp >> shift) & 0x0f);
2202
2203 if (shift == 4)
2204 {
2205 shift = 0;
2206 sp--;
2207 }
2208
2209 else
2210 shift = 4;
2211
2212 dp--;
2213 }
2214 break;
2215 }
2216
2217 default:
2218 break;
2219 }
2220 row_info->bit_depth = 8;
2221 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2222 row_info->rowbytes = row_width * row_info->channels;
2223 }
2224 }
2225 #endif
2226
2227 #ifdef PNG_READ_SHIFT_SUPPORTED
2228 /* Reverse the effects of png_do_shift. This routine merely shifts the
2229 * pixels back to their significant bits values. Thus, if you have
2230 * a row of bit depth 8, but only 5 are significant, this will shift
2231 * the values back to 0 through 31.
2232 */
2233 static void
2234 png_do_unshift(png_row_infop row_info, png_bytep row,
2235 png_const_color_8p sig_bits)
2236 {
2237 int color_type;
2238
2239 png_debug(1, "in png_do_unshift");
2240
2241 /* The palette case has already been handled in the _init routine. */
2242 color_type = row_info->color_type;
2243
2244 if (color_type != PNG_COLOR_TYPE_PALETTE)
2245 {
2246 int shift[4];
2247 int channels = 0;
2248 int bit_depth = row_info->bit_depth;
2249
2250 if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
2251 {
2252 shift[channels++] = bit_depth - sig_bits->red;
2253 shift[channels++] = bit_depth - sig_bits->green;
2254 shift[channels++] = bit_depth - sig_bits->blue;
2255 }
2256
2257 else
2258 {
2259 shift[channels++] = bit_depth - sig_bits->gray;
2260 }
2261
2262 if ((color_type & PNG_COLOR_MASK_ALPHA) != 0)
2263 {
2264 shift[channels++] = bit_depth - sig_bits->alpha;
2265 }
2266
2267 {
2268 int c, have_shift;
2269
2270 for (c = have_shift = 0; c < channels; ++c)
2271 {
2272 /* A shift of more than the bit depth is an error condition but it
2273 * gets ignored here.
2274 */
2275 if (shift[c] <= 0 || shift[c] >= bit_depth)
2276 shift[c] = 0;
2277
2278 else
2279 have_shift = 1;
2280 }
2281
2282 if (have_shift == 0)
2283 return;
2284 }
2285
2286 switch (bit_depth)
2287 {
2288 default:
2289 /* Must be 1bpp gray: should not be here! */
2290 /* NOTREACHED */
2291 break;
2292
2293 case 2:
2294 /* Must be 2bpp gray */
2295 /* assert(channels == 1 && shift[0] == 1) */
2296 {
2297 png_bytep bp = row;
2298 png_bytep bp_end = bp + row_info->rowbytes;
2299
2300 while (bp < bp_end)
2301 {
2302 int b = (*bp >> 1) & 0x55;
2303 *bp++ = (png_byte)b;
2304 }
2305 break;
2306 }
2307
2308 case 4:
2309 /* Must be 4bpp gray */
2310 /* assert(channels == 1) */
2311 {
2312 png_bytep bp = row;
2313 png_bytep bp_end = bp + row_info->rowbytes;
2314 int gray_shift = shift[0];
2315 int mask = 0xf >> gray_shift;
2316
2317 mask |= mask << 4;
2318
2319 while (bp < bp_end)
2320 {
2321 int b = (*bp >> gray_shift) & mask;
2322 *bp++ = (png_byte)b;
2323 }
2324 break;
2325 }
2326
2327 case 8:
2328 /* Single byte components, G, GA, RGB, RGBA */
2329 {
2330 png_bytep bp = row;
2331 png_bytep bp_end = bp + row_info->rowbytes;
2332 int channel = 0;
2333
2334 while (bp < bp_end)
2335 {
2336 int b = *bp >> shift[channel];
2337 if (++channel >= channels)
2338 channel = 0;
2339 *bp++ = (png_byte)b;
2340 }
2341 break;
2342 }
2343
2344 #ifdef PNG_READ_16BIT_SUPPORTED
2345 case 16:
2346 /* Double byte components, G, GA, RGB, RGBA */
2347 {
2348 png_bytep bp = row;
2349 png_bytep bp_end = bp + row_info->rowbytes;
2350 int channel = 0;
2351
2352 while (bp < bp_end)
2353 {
2354 int value = (bp[0] << 8) + bp[1];
2355
2356 value >>= shift[channel];
2357 if (++channel >= channels)
2358 channel = 0;
2359 *bp++ = (png_byte)(value >> 8);
2360 *bp++ = (png_byte)value;
2361 }
2362 break;
2363 }
2364 #endif
2365 }
2366 }
2367 }
2368 #endif
2369
2370 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2371 /* Scale rows of bit depth 16 down to 8 accurately */
2372 static void
2373 png_do_scale_16_to_8(png_row_infop row_info, png_bytep row)
2374 {
2375 png_debug(1, "in png_do_scale_16_to_8");
2376
2377 if (row_info->bit_depth == 16)
2378 {
2379 png_bytep sp = row; /* source */
2380 png_bytep dp = row; /* destination */
2381 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2382
2383 while (sp < ep)
2384 {
2385 /* The input is an array of 16 bit components, these must be scaled to
2386 * 8 bits each. For a 16 bit value V the required value (from the PNG
2387 * specification) is:
2388 *
2389 * (V * 255) / 65535
2390 *
2391 * This reduces to round(V / 257), or floor((V + 128.5)/257)
2392 *
2393 * Represent V as the two byte value vhi.vlo. Make a guess that the
2394 * result is the top byte of V, vhi, then the correction to this value
2395 * is:
2396 *
2397 * error = floor(((V-vhi.vhi) + 128.5) / 257)
2398 * = floor(((vlo-vhi) + 128.5) / 257)
2399 *
2400 * This can be approximated using integer arithmetic (and a signed
2401 * shift):
2402 *
2403 * error = (vlo-vhi+128) >> 8;
2404 *
2405 * The approximate differs from the exact answer only when (vlo-vhi) is
2406 * 128; it then gives a correction of +1 when the exact correction is
2407 * 0. This gives 128 errors. The exact answer (correct for all 16 bit
2408 * input values) is:
2409 *
2410 * error = (vlo-vhi+128)*65535 >> 24;
2411 *
2412 * An alternative arithmetic calculation which also gives no errors is:
2413 *
2414 * (V * 255 + 32895) >> 16
2415 */
2416
2417 png_int_32 tmp = *sp++; /* must be signed! */
2418 tmp += (((int)*sp++ - tmp + 128) * 65535) >> 24;
2419 *dp++ = (png_byte)tmp;
2420 }
2421
2422 row_info->bit_depth = 8;
2423 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2424 row_info->rowbytes = row_info->width * row_info->channels;
2425 }
2426 }
2427 #endif
2428
2429 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2430 static void
2431 /* Simply discard the low byte. This was the default behavior prior
2432 * to libpng-1.5.4.
2433 */
2434 png_do_chop(png_row_infop row_info, png_bytep row)
2435 {
2436 png_debug(1, "in png_do_chop");
2437
2438 if (row_info->bit_depth == 16)
2439 {
2440 png_bytep sp = row; /* source */
2441 png_bytep dp = row; /* destination */
2442 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2443
2444 while (sp < ep)
2445 {
2446 *dp++ = *sp;
2447 sp += 2; /* skip low byte */
2448 }
2449
2450 row_info->bit_depth = 8;
2451 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2452 row_info->rowbytes = row_info->width * row_info->channels;
2453 }
2454 }
2455 #endif
2456
2457 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
2458 static void
2459 png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
2460 {
2461 png_debug(1, "in png_do_read_swap_alpha");
2462
2463 {
2464 png_uint_32 row_width = row_info->width;
2465 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2466 {
2467 /* This converts from RGBA to ARGB */
2468 if (row_info->bit_depth == 8)
2469 {
2470 png_bytep sp = row + row_info->rowbytes;
2471 png_bytep dp = sp;
2472 png_byte save;
2473 png_uint_32 i;
2474
2475 for (i = 0; i < row_width; i++)
2476 {
2477 save = *(--sp);
2478 *(--dp) = *(--sp);
2479 *(--dp) = *(--sp);
2480 *(--dp) = *(--sp);
2481 *(--dp) = save;
2482 }
2483 }
2484
2485 #ifdef PNG_READ_16BIT_SUPPORTED
2486 /* This converts from RRGGBBAA to AARRGGBB */
2487 else
2488 {
2489 png_bytep sp = row + row_info->rowbytes;
2490 png_bytep dp = sp;
2491 png_byte save[2];
2492 png_uint_32 i;
2493
2494 for (i = 0; i < row_width; i++)
2495 {
2496 save[0] = *(--sp);
2497 save[1] = *(--sp);
2498 *(--dp) = *(--sp);
2499 *(--dp) = *(--sp);
2500 *(--dp) = *(--sp);
2501 *(--dp) = *(--sp);
2502 *(--dp) = *(--sp);
2503 *(--dp) = *(--sp);
2504 *(--dp) = save[0];
2505 *(--dp) = save[1];
2506 }
2507 }
2508 #endif
2509 }
2510
2511 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2512 {
2513 /* This converts from GA to AG */
2514 if (row_info->bit_depth == 8)
2515 {
2516 png_bytep sp = row + row_info->rowbytes;
2517 png_bytep dp = sp;
2518 png_byte save;
2519 png_uint_32 i;
2520
2521 for (i = 0; i < row_width; i++)
2522 {
2523 save = *(--sp);
2524 *(--dp) = *(--sp);
2525 *(--dp) = save;
2526 }
2527 }
2528
2529 #ifdef PNG_READ_16BIT_SUPPORTED
2530 /* This converts from GGAA to AAGG */
2531 else
2532 {
2533 png_bytep sp = row + row_info->rowbytes;
2534 png_bytep dp = sp;
2535 png_byte save[2];
2536 png_uint_32 i;
2537
2538 for (i = 0; i < row_width; i++)
2539 {
2540 save[0] = *(--sp);
2541 save[1] = *(--sp);
2542 *(--dp) = *(--sp);
2543 *(--dp) = *(--sp);
2544 *(--dp) = save[0];
2545 *(--dp) = save[1];
2546 }
2547 }
2548 #endif
2549 }
2550 }
2551 }
2552 #endif
2553
2554 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
2555 static void
2556 png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
2557 {
2558 png_uint_32 row_width;
2559 png_debug(1, "in png_do_read_invert_alpha");
2560
2561 row_width = row_info->width;
2562 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2563 {
2564 if (row_info->bit_depth == 8)
2565 {
2566 /* This inverts the alpha channel in RGBA */
2567 png_bytep sp = row + row_info->rowbytes;
2568 png_bytep dp = sp;
2569 png_uint_32 i;
2570
2571 for (i = 0; i < row_width; i++)
2572 {
2573 *(--dp) = (png_byte)(255 - *(--sp));
2574
2575 /* This does nothing:
2576 *(--dp) = *(--sp);
2577 *(--dp) = *(--sp);
2578 *(--dp) = *(--sp);
2579 We can replace it with:
2580 */
2581 sp-=3;
2582 dp=sp;
2583 }
2584 }
2585
2586 #ifdef PNG_READ_16BIT_SUPPORTED
2587 /* This inverts the alpha channel in RRGGBBAA */
2588 else
2589 {
2590 png_bytep sp = row + row_info->rowbytes;
2591 png_bytep dp = sp;
2592 png_uint_32 i;
2593
2594 for (i = 0; i < row_width; i++)
2595 {
2596 *(--dp) = (png_byte)(255 - *(--sp));
2597 *(--dp) = (png_byte)(255 - *(--sp));
2598
2599 /* This does nothing:
2600 *(--dp) = *(--sp);
2601 *(--dp) = *(--sp);
2602 *(--dp) = *(--sp);
2603 *(--dp) = *(--sp);
2604 *(--dp) = *(--sp);
2605 *(--dp) = *(--sp);
2606 We can replace it with:
2607 */
2608 sp-=6;
2609 dp=sp;
2610 }
2611 }
2612 #endif
2613 }
2614 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2615 {
2616 if (row_info->bit_depth == 8)
2617 {
2618 /* This inverts the alpha channel in GA */
2619 png_bytep sp = row + row_info->rowbytes;
2620 png_bytep dp = sp;
2621 png_uint_32 i;
2622
2623 for (i = 0; i < row_width; i++)
2624 {
2625 *(--dp) = (png_byte)(255 - *(--sp));
2626 *(--dp) = *(--sp);
2627 }
2628 }
2629
2630 #ifdef PNG_READ_16BIT_SUPPORTED
2631 else
2632 {
2633 /* This inverts the alpha channel in GGAA */
2634 png_bytep sp = row + row_info->rowbytes;
2635 png_bytep dp = sp;
2636 png_uint_32 i;
2637
2638 for (i = 0; i < row_width; i++)
2639 {
2640 *(--dp) = (png_byte)(255 - *(--sp));
2641 *(--dp) = (png_byte)(255 - *(--sp));
2642 /*
2643 *(--dp) = *(--sp);
2644 *(--dp) = *(--sp);
2645 */
2646 sp-=2;
2647 dp=sp;
2648 }
2649 }
2650 #endif
2651 }
2652 }
2653 #endif
2654
2655 #ifdef PNG_READ_FILLER_SUPPORTED
2656 /* Add filler channel if we have RGB color */
2657 static void
2658 png_do_read_filler(png_row_infop row_info, png_bytep row,
2659 png_uint_32 filler, png_uint_32 flags)
2660 {
2661 png_uint_32 i;
2662 png_uint_32 row_width = row_info->width;
2663
2664 #ifdef PNG_READ_16BIT_SUPPORTED
2665 png_byte hi_filler = (png_byte)(filler>>8);
2666 #endif
2667 png_byte lo_filler = (png_byte)filler;
2668
2669 png_debug(1, "in png_do_read_filler");
2670
2671 if (
2672 row_info->color_type == PNG_COLOR_TYPE_GRAY)
2673 {
2674 if (row_info->bit_depth == 8)
2675 {
2676 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2677 {
2678 /* This changes the data from G to GX */
2679 png_bytep sp = row + (png_size_t)row_width;
2680 png_bytep dp = sp + (png_size_t)row_width;
2681 for (i = 1; i < row_width; i++)
2682 {
2683 *(--dp) = lo_filler;
2684 *(--dp) = *(--sp);
2685 }
2686 *(--dp) = lo_filler;
2687 row_info->channels = 2;
2688 row_info->pixel_depth = 16;
2689 row_info->rowbytes = row_width * 2;
2690 }
2691
2692 else
2693 {
2694 /* This changes the data from G to XG */
2695 png_bytep sp = row + (png_size_t)row_width;
2696 png_bytep dp = sp + (png_size_t)row_width;
2697 for (i = 0; i < row_width; i++)
2698 {
2699 *(--dp) = *(--sp);
2700 *(--dp) = lo_filler;
2701 }
2702 row_info->channels = 2;
2703 row_info->pixel_depth = 16;
2704 row_info->rowbytes = row_width * 2;
2705 }
2706 }
2707
2708 #ifdef PNG_READ_16BIT_SUPPORTED
2709 else if (row_info->bit_depth == 16)
2710 {
2711 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2712 {
2713 /* This changes the data from GG to GGXX */
2714 png_bytep sp = row + (png_size_t)row_width * 2;
2715 png_bytep dp = sp + (png_size_t)row_width * 2;
2716 for (i = 1; i < row_width; i++)
2717 {
2718 *(--dp) = lo_filler;
2719 *(--dp) = hi_filler;
2720 *(--dp) = *(--sp);
2721 *(--dp) = *(--sp);
2722 }
2723 *(--dp) = lo_filler;
2724 *(--dp) = hi_filler;
2725 row_info->channels = 2;
2726 row_info->pixel_depth = 32;
2727 row_info->rowbytes = row_width * 4;
2728 }
2729
2730 else
2731 {
2732 /* This changes the data from GG to XXGG */
2733 png_bytep sp = row + (png_size_t)row_width * 2;
2734 png_bytep dp = sp + (png_size_t)row_width * 2;
2735 for (i = 0; i < row_width; i++)
2736 {
2737 *(--dp) = *(--sp);
2738 *(--dp) = *(--sp);
2739 *(--dp) = lo_filler;
2740 *(--dp) = hi_filler;
2741 }
2742 row_info->channels = 2;
2743 row_info->pixel_depth = 32;
2744 row_info->rowbytes = row_width * 4;
2745 }
2746 }
2747 #endif
2748 } /* COLOR_TYPE == GRAY */
2749 else if (row_info->color_type == PNG_COLOR_TYPE_RGB)
2750 {
2751 if (row_info->bit_depth == 8)
2752 {
2753 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2754 {
2755 /* This changes the data from RGB to RGBX */
2756 png_bytep sp = row + (png_size_t)row_width * 3;
2757 png_bytep dp = sp + (png_size_t)row_width;
2758 for (i = 1; i < row_width; i++)
2759 {
2760 *(--dp) = lo_filler;
2761 *(--dp) = *(--sp);
2762 *(--dp) = *(--sp);
2763 *(--dp) = *(--sp);
2764 }
2765 *(--dp) = lo_filler;
2766 row_info->channels = 4;
2767 row_info->pixel_depth = 32;
2768 row_info->rowbytes = row_width * 4;
2769 }
2770
2771 else
2772 {
2773 /* This changes the data from RGB to XRGB */
2774 png_bytep sp = row + (png_size_t)row_width * 3;
2775 png_bytep dp = sp + (png_size_t)row_width;
2776 for (i = 0; i < row_width; i++)
2777 {
2778 *(--dp) = *(--sp);
2779 *(--dp) = *(--sp);
2780 *(--dp) = *(--sp);
2781 *(--dp) = lo_filler;
2782 }
2783 row_info->channels = 4;
2784 row_info->pixel_depth = 32;
2785 row_info->rowbytes = row_width * 4;
2786 }
2787 }
2788
2789 #ifdef PNG_READ_16BIT_SUPPORTED
2790 else if (row_info->bit_depth == 16)
2791 {
2792 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2793 {
2794 /* This changes the data from RRGGBB to RRGGBBXX */
2795 png_bytep sp = row + (png_size_t)row_width * 6;
2796 png_bytep dp = sp + (png_size_t)row_width * 2;
2797 for (i = 1; i < row_width; i++)
2798 {
2799 *(--dp) = lo_filler;
2800 *(--dp) = hi_filler;
2801 *(--dp) = *(--sp);
2802 *(--dp) = *(--sp);
2803 *(--dp) = *(--sp);
2804 *(--dp) = *(--sp);
2805 *(--dp) = *(--sp);
2806 *(--dp) = *(--sp);
2807 }
2808 *(--dp) = lo_filler;
2809 *(--dp) = hi_filler;
2810 row_info->channels = 4;
2811 row_info->pixel_depth = 64;
2812 row_info->rowbytes = row_width * 8;
2813 }
2814
2815 else
2816 {
2817 /* This changes the data from RRGGBB to XXRRGGBB */
2818 png_bytep sp = row + (png_size_t)row_width * 6;
2819 png_bytep dp = sp + (png_size_t)row_width * 2;
2820 for (i = 0; i < row_width; i++)
2821 {
2822 *(--dp) = *(--sp);
2823 *(--dp) = *(--sp);
2824 *(--dp) = *(--sp);
2825 *(--dp) = *(--sp);
2826 *(--dp) = *(--sp);
2827 *(--dp) = *(--sp);
2828 *(--dp) = lo_filler;
2829 *(--dp) = hi_filler;
2830 }
2831
2832 row_info->channels = 4;
2833 row_info->pixel_depth = 64;
2834 row_info->rowbytes = row_width * 8;
2835 }
2836 }
2837 #endif
2838 } /* COLOR_TYPE == RGB */
2839 }
2840 #endif
2841
2842 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2843 /* Expand grayscale files to RGB, with or without alpha */
2844 static void
2845 png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
2846 {
2847 png_uint_32 i;
2848 png_uint_32 row_width = row_info->width;
2849
2850 png_debug(1, "in png_do_gray_to_rgb");
2851
2852 if (row_info->bit_depth >= 8 &&
2853 (row_info->color_type & PNG_COLOR_MASK_COLOR) == 0)
2854 {
2855 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
2856 {
2857 if (row_info->bit_depth == 8)
2858 {
2859 /* This changes G to RGB */
2860 png_bytep sp = row + (png_size_t)row_width - 1;
2861 png_bytep dp = sp + (png_size_t)row_width * 2;
2862 for (i = 0; i < row_width; i++)
2863 {
2864 *(dp--) = *sp;
2865 *(dp--) = *sp;
2866 *(dp--) = *(sp--);
2867 }
2868 }
2869
2870 else
2871 {
2872 /* This changes GG to RRGGBB */
2873 png_bytep sp = row + (png_size_t)row_width * 2 - 1;
2874 png_bytep dp = sp + (png_size_t)row_width * 4;
2875 for (i = 0; i < row_width; i++)
2876 {
2877 *(dp--) = *sp;
2878 *(dp--) = *(sp - 1);
2879 *(dp--) = *sp;
2880 *(dp--) = *(sp - 1);
2881 *(dp--) = *(sp--);
2882 *(dp--) = *(sp--);
2883 }
2884 }
2885 }
2886
2887 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2888 {
2889 if (row_info->bit_depth == 8)
2890 {
2891 /* This changes GA to RGBA */
2892 png_bytep sp = row + (png_size_t)row_width * 2 - 1;
2893 png_bytep dp = sp + (png_size_t)row_width * 2;
2894 for (i = 0; i < row_width; i++)
2895 {
2896 *(dp--) = *(sp--);
2897 *(dp--) = *sp;
2898 *(dp--) = *sp;
2899 *(dp--) = *(sp--);
2900 }
2901 }
2902
2903 else
2904 {
2905 /* This changes GGAA to RRGGBBAA */
2906 png_bytep sp = row + (png_size_t)row_width * 4 - 1;
2907 png_bytep dp = sp + (png_size_t)row_width * 4;
2908 for (i = 0; i < row_width; i++)
2909 {
2910 *(dp--) = *(sp--);
2911 *(dp--) = *(sp--);
2912 *(dp--) = *sp;
2913 *(dp--) = *(sp - 1);
2914 *(dp--) = *sp;
2915 *(dp--) = *(sp - 1);
2916 *(dp--) = *(sp--);
2917 *(dp--) = *(sp--);
2918 }
2919 }
2920 }
2921 row_info->channels = (png_byte)(row_info->channels + 2);
2922 row_info->color_type |= PNG_COLOR_MASK_COLOR;
2923 row_info->pixel_depth = (png_byte)(row_info->channels *
2924 row_info->bit_depth);
2925 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
2926 }
2927 }
2928 #endif
2929
2930 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2931 /* Reduce RGB files to grayscale, with or without alpha
2932 * using the equation given in Poynton's ColorFAQ of 1998-01-04 at
2933 * <http://www.inforamp.net/~poynton/> (THIS LINK IS DEAD June 2008 but
2934 * versions dated 1998 through November 2002 have been archived at
2935 * http://web.archive.org/web/20000816232553/http://www.inforamp.net/
2936 * ~poynton/notes/colour_and_gamma/ColorFAQ.txt )
2937 * Charles Poynton poynton at poynton.com
2938 *
2939 * Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
2940 *
2941 * which can be expressed with integers as
2942 *
2943 * Y = (6969 * R + 23434 * G + 2365 * B)/32768
2944 *
2945 * Poynton's current link (as of January 2003 through July 2011):
2946 * <http://www.poynton.com/notes/colour_and_gamma/>
2947 * has changed the numbers slightly:
2948 *
2949 * Y = 0.2126*R + 0.7152*G + 0.0722*B
2950 *
2951 * which can be expressed with integers as
2952 *
2953 * Y = (6966 * R + 23436 * G + 2366 * B)/32768
2954 *
2955 * Historically, however, libpng uses numbers derived from the ITU-R Rec 709
2956 * end point chromaticities and the D65 white point. Depending on the
2957 * precision used for the D65 white point this produces a variety of different
2958 * numbers, however if the four decimal place value used in ITU-R Rec 709 is
2959 * used (0.3127,0.3290) the Y calculation would be:
2960 *
2961 * Y = (6968 * R + 23435 * G + 2366 * B)/32768
2962 *
2963 * While this is correct the rounding results in an overflow for white, because
2964 * the sum of the rounded coefficients is 32769, not 32768. Consequently
2965 * libpng uses, instead, the closest non-overflowing approximation:
2966 *
2967 * Y = (6968 * R + 23434 * G + 2366 * B)/32768
2968 *
2969 * Starting with libpng-1.5.5, if the image being converted has a cHRM chunk
2970 * (including an sRGB chunk) then the chromaticities are used to calculate the
2971 * coefficients. See the chunk handling in pngrutil.c for more information.
2972 *
2973 * In all cases the calculation is to be done in a linear colorspace. If no
2974 * gamma information is available to correct the encoding of the original RGB
2975 * values this results in an implicit assumption that the original PNG RGB
2976 * values were linear.
2977 *
2978 * Other integer coefficents can be used via png_set_rgb_to_gray(). Because
2979 * the API takes just red and green coefficients the blue coefficient is
2980 * calculated to make the sum 32768. This will result in different rounding
2981 * to that used above.
2982 */
2983 static int
2984 png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
2985
2986 {
2987 int rgb_error = 0;
2988
2989 png_debug(1, "in png_do_rgb_to_gray");
2990
2991 if ((row_info->color_type & PNG_COLOR_MASK_PALETTE) == 0 &&
2992 (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
2993 {
2994 PNG_CONST png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff;
2995 PNG_CONST png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff;
2996 PNG_CONST png_uint_32 bc = 32768 - rc - gc;
2997 PNG_CONST png_uint_32 row_width = row_info->width;
2998 PNG_CONST int have_alpha =
2999 (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0;
3000
3001 if (row_info->bit_depth == 8)
3002 {
3003 #ifdef PNG_READ_GAMMA_SUPPORTED
3004 /* Notice that gamma to/from 1 are not necessarily inverses (if
3005 * there is an overall gamma correction). Prior to 1.5.5 this code
3006 * checked the linearized values for equality; this doesn't match
3007 * the documentation, the original values must be checked.
3008 */
3009 if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL)
3010 {
3011 png_bytep sp = row;
3012 png_bytep dp = row;
3013 png_uint_32 i;
3014
3015 for (i = 0; i < row_width; i++)
3016 {
3017 png_byte red = *(sp++);
3018 png_byte green = *(sp++);
3019 png_byte blue = *(sp++);
3020
3021 if (red != green || red != blue)
3022 {
3023 red = png_ptr->gamma_to_1[red];
3024 green = png_ptr->gamma_to_1[green];
3025 blue = png_ptr->gamma_to_1[blue];
3026
3027 rgb_error |= 1;
3028 *(dp++) = png_ptr->gamma_from_1[
3029 (rc*red + gc*green + bc*blue + 16384)>>15];
3030 }
3031
3032 else
3033 {
3034 /* If there is no overall correction the table will not be
3035 * set.
3036 */
3037 if (png_ptr->gamma_table != NULL)
3038 red = png_ptr->gamma_table[red];
3039
3040 *(dp++) = red;
3041 }
3042
3043 if (have_alpha != 0)
3044 *(dp++) = *(sp++);
3045 }
3046 }
3047 else
3048 #endif
3049 {
3050 png_bytep sp = row;
3051 png_bytep dp = row;
3052 png_uint_32 i;
3053
3054 for (i = 0; i < row_width; i++)
3055 {
3056 png_byte red = *(sp++);
3057 png_byte green = *(sp++);
3058 png_byte blue = *(sp++);
3059
3060 if (red != green || red != blue)
3061 {
3062 rgb_error |= 1;
3063 /* NOTE: this is the historical approach which simply
3064 * truncates the results.
3065 */
3066 *(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15);
3067 }
3068
3069 else
3070 *(dp++) = red;
3071
3072 if (have_alpha != 0)
3073 *(dp++) = *(sp++);
3074 }
3075 }
3076 }
3077
3078 else /* RGB bit_depth == 16 */
3079 {
3080 #ifdef PNG_READ_GAMMA_SUPPORTED
3081 if (png_ptr->gamma_16_to_1 != NULL && png_ptr->gamma_16_from_1 != NULL)
3082 {
3083 png_bytep sp = row;
3084 png_bytep dp = row;
3085 png_uint_32 i;
3086
3087 for (i = 0; i < row_width; i++)
3088 {
3089 png_uint_16 red, green, blue, w;
3090 png_byte hi,lo;
3091
3092 hi=*(sp)++; lo=*(sp)++; red = (png_uint_16)((hi << 8) | (lo));
3093 hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo));
3094 hi=*(sp)++; lo=*(sp)++; blue = (png_uint_16)((hi << 8) | (lo));
3095
3096 if (red == green && red == blue)
3097 {
3098 if (png_ptr->gamma_16_table != NULL)
3099 w = png_ptr->gamma_16_table[(red & 0xff)
3100 >> png_ptr->gamma_shift][red >> 8];
3101
3102 else
3103 w = red;
3104 }
3105
3106 else
3107 {
3108 png_uint_16 red_1 = png_ptr->gamma_16_to_1[(red & 0xff)
3109 >> png_ptr->gamma_shift][red>>8];
3110 png_uint_16 green_1 =
3111 png_ptr->gamma_16_to_1[(green & 0xff) >>
3112 png_ptr->gamma_shift][green>>8];
3113 png_uint_16 blue_1 = png_ptr->gamma_16_to_1[(blue & 0xff)
3114 >> png_ptr->gamma_shift][blue>>8];
3115 png_uint_16 gray16 = (png_uint_16)((rc*red_1 + gc*green_1
3116 + bc*blue_1 + 16384)>>15);
3117 w = png_ptr->gamma_16_from_1[(gray16 & 0xff) >>
3118 png_ptr->gamma_shift][gray16 >> 8];
3119 rgb_error |= 1;
3120 }
3121
3122 *(dp++) = (png_byte)((w>>8) & 0xff);
3123 *(dp++) = (png_byte)(w & 0xff);
3124
3125 if (have_alpha != 0)
3126 {
3127 *(dp++) = *(sp++);
3128 *(dp++) = *(sp++);
3129 }
3130 }
3131 }
3132 else
3133 #endif
3134 {
3135 png_bytep sp = row;
3136 png_bytep dp = row;
3137 png_uint_32 i;
3138
3139 for (i = 0; i < row_width; i++)
3140 {
3141 png_uint_16 red, green, blue, gray16;
3142 png_byte hi,lo;
3143
3144 hi=*(sp)++; lo=*(sp)++; red = (png_uint_16)((hi << 8) | (lo));
3145 hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo));
3146 hi=*(sp)++; lo=*(sp)++; blue = (png_uint_16)((hi << 8) | (lo));
3147
3148 if (red != green || red != blue)
3149 rgb_error |= 1;
3150
3151 /* From 1.5.5 in the 16 bit case do the accurate conversion even
3152 * in the 'fast' case - this is because this is where the code
3153 * ends up when handling linear 16 bit data.
3154 */
3155 gray16 = (png_uint_16)((rc*red + gc*green + bc*blue + 16384) >>
3156 15);
3157 *(dp++) = (png_byte)((gray16 >> 8) & 0xff);
3158 *(dp++) = (png_byte)(gray16 & 0xff);
3159
3160 if (have_alpha != 0)
3161 {
3162 *(dp++) = *(sp++);
3163 *(dp++) = *(sp++);
3164 }
3165 }
3166 }
3167 }
3168
3169 row_info->channels = (png_byte)(row_info->channels - 2);
3170 row_info->color_type = (png_byte)(row_info->color_type &
3171 ~PNG_COLOR_MASK_COLOR);
3172 row_info->pixel_depth = (png_byte)(row_info->channels *
3173 row_info->bit_depth);
3174 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
3175 }
3176 return rgb_error;
3177 }
3178 #endif
3179
3180 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
3181 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
3182 /* Replace any alpha or transparency with the supplied background color.
3183 * "background" is already in the screen gamma, while "background_1" is
3184 * at a gamma of 1.0. Paletted files have already been taken care of.
3185 */
3186 static void
3187 png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
3188 {
3189 #ifdef PNG_READ_GAMMA_SUPPORTED
3190 png_const_bytep gamma_table = png_ptr->gamma_table;
3191 png_const_bytep gamma_from_1 = png_ptr->gamma_from_1;
3192 png_const_bytep gamma_to_1 = png_ptr->gamma_to_1;
3193 png_const_uint_16pp gamma_16 = png_ptr->gamma_16_table;
3194 png_const_uint_16pp gamma_16_from_1 = png_ptr->gamma_16_from_1;
3195 png_const_uint_16pp gamma_16_to_1 = png_ptr->gamma_16_to_1;
3196 int gamma_shift = png_ptr->gamma_shift;
3197 int optimize = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0;
3198 #endif
3199
3200 png_bytep sp;
3201 png_uint_32 i;
3202 png_uint_32 row_width = row_info->width;
3203 int shift;
3204
3205 png_debug(1, "in png_do_compose");
3206
3207 {
3208 switch (row_info->color_type)
3209 {
3210 case PNG_COLOR_TYPE_GRAY:
3211 {
3212 switch (row_info->bit_depth)
3213 {
3214 case 1:
3215 {
3216 sp = row;
3217 shift = 7;
3218 for (i = 0; i < row_width; i++)
3219 {
3220 if ((png_uint_16)((*sp >> shift) & 0x01)
3221 == png_ptr->trans_color.gray)
3222 {
3223 unsigned int tmp = *sp & (0x7f7f >> (7 - shift));
3224 tmp |= png_ptr->background.gray << shift;
3225 *sp = (png_byte)(tmp & 0xff);
3226 }
3227
3228 if (shift == 0)
3229 {
3230 shift = 7;
3231 sp++;
3232 }
3233
3234 else
3235 shift--;
3236 }
3237 break;
3238 }
3239
3240 case 2:
3241 {
3242 #ifdef PNG_READ_GAMMA_SUPPORTED
3243 if (gamma_table != NULL)
3244 {
3245 sp = row;
3246 shift = 6;
3247 for (i = 0; i < row_width; i++)
3248 {
3249 if ((png_uint_16)((*sp >> shift) & 0x03)
3250 == png_ptr->trans_color.gray)
3251 {
3252 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3253 tmp |= png_ptr->background.gray << shift;
3254 *sp = (png_byte)(tmp & 0xff);
3255 }
3256
3257 else
3258 {
3259 unsigned int p = (*sp >> shift) & 0x03;
3260 unsigned int g = (gamma_table [p | (p << 2) |
3261 (p << 4) | (p << 6)] >> 6) & 0x03;
3262 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3263 tmp |= g << shift;
3264 *sp = (png_byte)(tmp & 0xff);
3265 }
3266
3267 if (shift == 0)
3268 {
3269 shift = 6;
3270 sp++;
3271 }
3272
3273 else
3274 shift -= 2;
3275 }
3276 }
3277
3278 else
3279 #endif
3280 {
3281 sp = row;
3282 shift = 6;
3283 for (i = 0; i < row_width; i++)
3284 {
3285 if ((png_uint_16)((*sp >> shift) & 0x03)
3286 == png_ptr->trans_color.gray)
3287 {
3288 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3289 tmp |= png_ptr->background.gray << shift;
3290 *sp = (png_byte)(tmp & 0xff);
3291 }
3292
3293 if (shift == 0)
3294 {
3295 shift = 6;
3296 sp++;
3297 }
3298
3299 else
3300 shift -= 2;
3301 }
3302 }
3303 break;
3304 }
3305
3306 case 4:
3307 {
3308 #ifdef PNG_READ_GAMMA_SUPPORTED
3309 if (gamma_table != NULL)
3310 {
3311 sp = row;
3312 shift = 4;
3313 for (i = 0; i < row_width; i++)
3314 {
3315 if ((png_uint_16)((*sp >> shift) & 0x0f)
3316 == png_ptr->trans_color.gray)
3317 {
3318 unsigned int tmp = *sp & (0xf0f >> (4 - shift));
3319 tmp |= png_ptr->background.gray << shift;
3320 *sp = (png_byte)(tmp & 0xff);
3321 }
3322
3323 else
3324 {
3325 unsigned int p = (*sp >> shift) & 0x0f;
3326 unsigned int g = (gamma_table[p | (p << 4)] >> 4) &
3327 0x0f;
3328 unsigned int tmp = *sp & (0xf0f >> (4 - shift));
3329 tmp |= g << shift;
3330 *sp = (png_byte)(tmp & 0xff);
3331 }
3332
3333 if (shift == 0)
3334 {
3335 shift = 4;
3336 sp++;
3337 }
3338
3339 else
3340 shift -= 4;
3341 }
3342 }
3343
3344 else
3345 #endif
3346 {
3347 sp = row;
3348 shift = 4;
3349 for (i = 0; i < row_width; i++)
3350 {
3351 if ((png_uint_16)((*sp >> shift) & 0x0f)
3352 == png_ptr->trans_color.gray)
3353 {
3354 unsigned int tmp = *sp & (0xf0f >> (4 - shift));
3355 tmp |= png_ptr->background.gray << shift;
3356 *sp = (png_byte)(tmp & 0xff);
3357 }
3358
3359 if (shift == 0)
3360 {
3361 shift = 4;
3362 sp++;
3363 }
3364
3365 else
3366 shift -= 4;
3367 }
3368 }
3369 break;
3370 }
3371
3372 case 8:
3373 {
3374 #ifdef PNG_READ_GAMMA_SUPPORTED
3375 if (gamma_table != NULL)
3376 {
3377 sp = row;
3378 for (i = 0; i < row_width; i++, sp++)
3379 {
3380 if (*sp == png_ptr->trans_color.gray)
3381 *sp = (png_byte)png_ptr->background.gray;
3382
3383 else
3384 *sp = gamma_table[*sp];
3385 }
3386 }
3387 else
3388 #endif
3389 {
3390 sp = row;
3391 for (i = 0; i < row_width; i++, sp++)
3392 {
3393 if (*sp == png_ptr->trans_color.gray)
3394 *sp = (png_byte)png_ptr->background.gray;
3395 }
3396 }
3397 break;
3398 }
3399
3400 case 16:
3401 {
3402 #ifdef PNG_READ_GAMMA_SUPPORTED
3403 if (gamma_16 != NULL)
3404 {
3405 sp = row;
3406 for (i = 0; i < row_width; i++, sp += 2)
3407 {
3408 png_uint_16 v;
3409
3410 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3411
3412 if (v == png_ptr->trans_color.gray)
3413 {
3414 /* Background is already in screen gamma */
3415 *sp = (png_byte)((png_ptr->background.gray >> 8)
3416 & 0xff);
3417 *(sp + 1) = (png_byte)(png_ptr->background.gray
3418 & 0xff);
3419 }
3420
3421 else
3422 {
3423 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3424 *sp = (png_byte)((v >> 8) & 0xff);
3425 *(sp + 1) = (png_byte)(v & 0xff);
3426 }
3427 }
3428 }
3429 else
3430 #endif
3431 {
3432 sp = row;
3433 for (i = 0; i < row_width; i++, sp += 2)
3434 {
3435 png_uint_16 v;
3436
3437 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3438
3439 if (v == png_ptr->trans_color.gray)
3440 {
3441 *sp = (png_byte)((png_ptr->background.gray >> 8)
3442 & 0xff);
3443 *(sp + 1) = (png_byte)(png_ptr->background.gray
3444 & 0xff);
3445 }
3446 }
3447 }
3448 break;
3449 }
3450
3451 default:
3452 break;
3453 }
3454 break;
3455 }
3456
3457 case PNG_COLOR_TYPE_RGB:
3458 {
3459 if (row_info->bit_depth == 8)
3460 {
3461 #ifdef PNG_READ_GAMMA_SUPPORTED
3462 if (gamma_table != NULL)
3463 {
3464 sp = row;
3465 for (i = 0; i < row_width; i++, sp += 3)
3466 {
3467 if (*sp == png_ptr->trans_color.red &&
3468 *(sp + 1) == png_ptr->trans_color.green &&
3469 *(sp + 2) == png_ptr->trans_color.blue)
3470 {
3471 *sp = (png_byte)png_ptr->background.red;
3472 *(sp + 1) = (png_byte)png_ptr->background.green;
3473 *(sp + 2) = (png_byte)png_ptr->background.blue;
3474 }
3475
3476 else
3477 {
3478 *sp = gamma_table[*sp];
3479 *(sp + 1) = gamma_table[*(sp + 1)];
3480 *(sp + 2) = gamma_table[*(sp + 2)];
3481 }
3482 }
3483 }
3484 else
3485 #endif
3486 {
3487 sp = row;
3488 for (i = 0; i < row_width; i++, sp += 3)
3489 {
3490 if (*sp == png_ptr->trans_color.red &&
3491 *(sp + 1) == png_ptr->trans_color.green &&
3492 *(sp + 2) == png_ptr->trans_color.blue)
3493 {
3494 *sp = (png_byte)png_ptr->background.red;
3495 *(sp + 1) = (png_byte)png_ptr->background.green;
3496 *(sp + 2) = (png_byte)png_ptr->background.blue;
3497 }
3498 }
3499 }
3500 }
3501 else /* if (row_info->bit_depth == 16) */
3502 {
3503 #ifdef PNG_READ_GAMMA_SUPPORTED
3504 if (gamma_16 != NULL)
3505 {
3506 sp = row;
3507 for (i = 0; i < row_width; i++, sp += 6)
3508 {
3509 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3510
3511 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3512 + *(sp + 3));
3513
3514 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3515 + *(sp + 5));
3516
3517 if (r == png_ptr->trans_color.red &&
3518 g == png_ptr->trans_color.green &&
3519 b == png_ptr->trans_color.blue)
3520 {
3521 /* Background is already in screen gamma */
3522 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3523 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3524 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3525 & 0xff);
3526 *(sp + 3) = (png_byte)(png_ptr->background.green
3527 & 0xff);
3528 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3529 & 0xff);
3530 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3531 }
3532
3533 else
3534 {
3535 png_uint_16 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3536 *sp = (png_byte)((v >> 8) & 0xff);
3537 *(sp + 1) = (png_byte)(v & 0xff);
3538
3539 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
3540 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3541 *(sp + 3) = (png_byte)(v & 0xff);
3542
3543 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
3544 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3545 *(sp + 5) = (png_byte)(v & 0xff);
3546 }
3547 }
3548 }
3549
3550 else
3551 #endif
3552 {
3553 sp = row;
3554 for (i = 0; i < row_width; i++, sp += 6)
3555 {
3556 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3557
3558 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3559 + *(sp + 3));
3560
3561 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3562 + *(sp + 5));
3563
3564 if (r == png_ptr->trans_color.red &&
3565 g == png_ptr->trans_color.green &&
3566 b == png_ptr->trans_color.blue)
3567 {
3568 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3569 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3570 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3571 & 0xff);
3572 *(sp + 3) = (png_byte)(png_ptr->background.green
3573 & 0xff);
3574 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3575 & 0xff);
3576 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3577 }
3578 }
3579 }
3580 }
3581 break;
3582 }
3583
3584 case PNG_COLOR_TYPE_GRAY_ALPHA:
3585 {
3586 if (row_info->bit_depth == 8)
3587 {
3588 #ifdef PNG_READ_GAMMA_SUPPORTED
3589 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
3590 gamma_table != NULL)
3591 {
3592 sp = row;
3593 for (i = 0; i < row_width; i++, sp += 2)
3594 {
3595 png_uint_16 a = *(sp + 1);
3596
3597 if (a == 0xff)
3598 *sp = gamma_table[*sp];
3599
3600 else if (a == 0)
3601 {
3602 /* Background is already in screen gamma */
3603 *sp = (png_byte)png_ptr->background.gray;
3604 }
3605
3606 else
3607 {
3608 png_byte v, w;
3609
3610 v = gamma_to_1[*sp];
3611 png_composite(w, v, a, png_ptr->background_1.gray);
3612 if (optimize == 0)
3613 w = gamma_from_1[w];
3614 *sp = w;
3615 }
3616 }
3617 }
3618 else
3619 #endif
3620 {
3621 sp = row;
3622 for (i = 0; i < row_width; i++, sp += 2)
3623 {
3624 png_byte a = *(sp + 1);
3625
3626 if (a == 0)
3627 *sp = (png_byte)png_ptr->background.gray;
3628
3629 else if (a < 0xff)
3630 png_composite(*sp, *sp, a, png_ptr->background.gray);
3631 }
3632 }
3633 }
3634 else /* if (png_ptr->bit_depth == 16) */
3635 {
3636 #ifdef PNG_READ_GAMMA_SUPPORTED
3637 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
3638 gamma_16_to_1 != NULL)
3639 {
3640 sp = row;
3641 for (i = 0; i < row_width; i++, sp += 4)
3642 {
3643 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
3644 + *(sp + 3));
3645
3646 if (a == (png_uint_16)0xffff)
3647 {
3648 png_uint_16 v;
3649
3650 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3651 *sp = (png_byte)((v >> 8) & 0xff);
3652 *(sp + 1) = (png_byte)(v & 0xff);
3653 }
3654
3655 else if (a == 0)
3656 {
3657 /* Background is already in screen gamma */
3658 *sp = (png_byte)((png_ptr->background.gray >> 8)
3659 & 0xff);
3660 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
3661 }
3662
3663 else
3664 {
3665