[THEMES]
[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 1.5.14 [January 24, 2013]
5 * Copyright (c) 1998-2013 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_structp 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_BACKGROUND_SUPPORTED
92 /* Handle alpha and tRNS via a background color */
93 void PNGFAPI
94 png_set_background_fixed(png_structp png_ptr,
95 png_const_color_16p background_color, int background_gamma_code,
96 int need_expand, png_fixed_point background_gamma)
97 {
98 png_debug(1, "in png_set_background_fixed");
99
100 if (png_ptr == NULL)
101 return;
102
103 if (background_gamma_code == PNG_BACKGROUND_GAMMA_UNKNOWN)
104 {
105 png_warning(png_ptr, "Application must supply a known background gamma");
106 return;
107 }
108
109 png_ptr->transformations |= PNG_COMPOSE | PNG_STRIP_ALPHA;
110 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
111 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
112
113 png_memcpy(&(png_ptr->background), background_color,
114 png_sizeof(png_color_16));
115 png_ptr->background_gamma = background_gamma;
116 png_ptr->background_gamma_type = (png_byte)(background_gamma_code);
117 if (need_expand)
118 png_ptr->transformations |= PNG_BACKGROUND_EXPAND;
119 else
120 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
121 }
122
123 # ifdef PNG_FLOATING_POINT_SUPPORTED
124 void PNGAPI
125 png_set_background(png_structp png_ptr,
126 png_const_color_16p background_color, int background_gamma_code,
127 int need_expand, double background_gamma)
128 {
129 png_set_background_fixed(png_ptr, background_color, background_gamma_code,
130 need_expand, png_fixed(png_ptr, background_gamma, "png_set_background"));
131 }
132 # endif /* FLOATING_POINT */
133 #endif /* READ_BACKGROUND */
134
135 /* Scale 16-bit depth files to 8-bit depth. If both of these are set then the
136 * one that pngrtran does first (scale) happens. This is necessary to allow the
137 * TRANSFORM and API behavior to be somewhat consistent, and it's simpler.
138 */
139 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
140 void PNGAPI
141 png_set_scale_16(png_structp png_ptr)
142 {
143 png_debug(1, "in png_set_scale_16");
144
145 if (png_ptr == NULL)
146 return;
147
148 png_ptr->transformations |= PNG_SCALE_16_TO_8;
149 }
150 #endif
151
152 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
153 /* Chop 16-bit depth files to 8-bit depth */
154 void PNGAPI
155 png_set_strip_16(png_structp png_ptr)
156 {
157 png_debug(1, "in png_set_strip_16");
158
159 if (png_ptr == NULL)
160 return;
161
162 png_ptr->transformations |= PNG_16_TO_8;
163 }
164 #endif
165
166 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
167 void PNGAPI
168 png_set_strip_alpha(png_structp png_ptr)
169 {
170 png_debug(1, "in png_set_strip_alpha");
171
172 if (png_ptr == NULL)
173 return;
174
175 png_ptr->transformations |= PNG_STRIP_ALPHA;
176 }
177 #endif
178
179 #if defined(PNG_READ_ALPHA_MODE_SUPPORTED) || defined(PNG_READ_GAMMA_SUPPORTED)
180 static png_fixed_point
181 translate_gamma_flags(png_structp png_ptr, png_fixed_point output_gamma,
182 int is_screen)
183 {
184 /* Check for flag values. The main reason for having the old Mac value as a
185 * flag is that it is pretty near impossible to work out what the correct
186 * value is from Apple documentation - a working Mac system is needed to
187 * discover the value!
188 */
189 if (output_gamma == PNG_DEFAULT_sRGB ||
190 output_gamma == PNG_FP_1 / PNG_DEFAULT_sRGB)
191 {
192 /* If there is no sRGB support this just sets the gamma to the standard
193 * sRGB value. (This is a side effect of using this function!)
194 */
195 # ifdef PNG_READ_sRGB_SUPPORTED
196 png_ptr->flags |= PNG_FLAG_ASSUME_sRGB;
197 # endif
198 if (is_screen)
199 output_gamma = PNG_GAMMA_sRGB;
200 else
201 output_gamma = PNG_GAMMA_sRGB_INVERSE;
202 }
203
204 else if (output_gamma == PNG_GAMMA_MAC_18 ||
205 output_gamma == PNG_FP_1 / PNG_GAMMA_MAC_18)
206 {
207 if (is_screen)
208 output_gamma = PNG_GAMMA_MAC_OLD;
209 else
210 output_gamma = PNG_GAMMA_MAC_INVERSE;
211 }
212
213 return output_gamma;
214 }
215
216 # ifdef PNG_FLOATING_POINT_SUPPORTED
217 static png_fixed_point
218 convert_gamma_value(png_structp png_ptr, double output_gamma)
219 {
220 /* The following silently ignores cases where fixed point (times 100,000)
221 * gamma values are passed to the floating point API. This is safe and it
222 * means the fixed point constants work just fine with the floating point
223 * API. The alternative would just lead to undetected errors and spurious
224 * bug reports. Negative values fail inside the _fixed API unless they
225 * correspond to the flag values.
226 */
227 if (output_gamma > 0 && output_gamma < 128)
228 output_gamma *= PNG_FP_1;
229
230 /* This preserves -1 and -2 exactly: */
231 output_gamma = floor(output_gamma + .5);
232
233 if (output_gamma > PNG_FP_MAX || output_gamma < PNG_FP_MIN)
234 png_fixed_error(png_ptr, "gamma value");
235
236 return (png_fixed_point)output_gamma;
237 }
238 # endif
239 #endif /* READ_ALPHA_MODE || READ_GAMMA */
240
241 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
242 void PNGFAPI
243 png_set_alpha_mode_fixed(png_structp png_ptr, int mode,
244 png_fixed_point output_gamma)
245 {
246 int compose = 0;
247 png_fixed_point file_gamma;
248
249 png_debug(1, "in png_set_alpha_mode");
250
251 if (png_ptr == NULL)
252 return;
253
254 output_gamma = translate_gamma_flags(png_ptr, output_gamma, 1/*screen*/);
255
256 /* Validate the value to ensure it is in a reasonable range. The value
257 * is expected to be 1 or greater, but this range test allows for some
258 * viewing correction values. The intent is to weed out users of this API
259 * who use the inverse of the gamma value accidentally! Since some of these
260 * values are reasonable this may have to be changed.
261 */
262 if (output_gamma < 70000 || output_gamma > 300000)
263 png_error(png_ptr, "output gamma out of expected range");
264
265 /* The default file gamma is the inverse of the output gamma; the output
266 * gamma may be changed below so get the file value first:
267 */
268 file_gamma = png_reciprocal(output_gamma);
269
270 /* There are really 8 possibilities here, composed of any combination
271 * of:
272 *
273 * premultiply the color channels
274 * do not encode non-opaque pixels
275 * encode the alpha as well as the color channels
276 *
277 * The differences disappear if the input/output ('screen') gamma is 1.0,
278 * because then the encoding is a no-op and there is only the choice of
279 * premultiplying the color channels or not.
280 *
281 * png_set_alpha_mode and png_set_background interact because both use
282 * png_compose to do the work. Calling both is only useful when
283 * png_set_alpha_mode is used to set the default mode - PNG_ALPHA_PNG - along
284 * with a default gamma value. Otherwise PNG_COMPOSE must not be set.
285 */
286 switch (mode)
287 {
288 case PNG_ALPHA_PNG: /* default: png standard */
289 /* No compose, but it may be set by png_set_background! */
290 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
291 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
292 break;
293
294 case PNG_ALPHA_ASSOCIATED: /* color channels premultiplied */
295 compose = 1;
296 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
297 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
298 /* The output is linear: */
299 output_gamma = PNG_FP_1;
300 break;
301
302 case PNG_ALPHA_OPTIMIZED: /* associated, non-opaque pixels linear */
303 compose = 1;
304 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
305 png_ptr->flags |= PNG_FLAG_OPTIMIZE_ALPHA;
306 /* output_gamma records the encoding of opaque pixels! */
307 break;
308
309 case PNG_ALPHA_BROKEN: /* associated, non-linear, alpha encoded */
310 compose = 1;
311 png_ptr->transformations |= PNG_ENCODE_ALPHA;
312 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
313 break;
314
315 default:
316 png_error(png_ptr, "invalid alpha mode");
317 }
318
319 /* Only set the default gamma if the file gamma has not been set (this has
320 * the side effect that the gamma in a second call to png_set_alpha_mode will
321 * be ignored.)
322 */
323 if (png_ptr->gamma == 0)
324 png_ptr->gamma = file_gamma;
325
326 /* But always set the output gamma: */
327 png_ptr->screen_gamma = output_gamma;
328
329 /* Finally, if pre-multiplying, set the background fields to achieve the
330 * desired result.
331 */
332 if (compose)
333 {
334 /* And obtain alpha pre-multiplication by composing on black: */
335 png_memset(&png_ptr->background, 0, sizeof png_ptr->background);
336 png_ptr->background_gamma = png_ptr->gamma; /* just in case */
337 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_FILE;
338 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
339
340 if (png_ptr->transformations & PNG_COMPOSE)
341 png_error(png_ptr,
342 "conflicting calls to set alpha mode and background");
343
344 png_ptr->transformations |= PNG_COMPOSE;
345 }
346
347 /* New API, make sure apps call the correct initializers: */
348 png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED;
349 }
350
351 # ifdef PNG_FLOATING_POINT_SUPPORTED
352 void PNGAPI
353 png_set_alpha_mode(png_structp png_ptr, int mode, double output_gamma)
354 {
355 png_set_alpha_mode_fixed(png_ptr, mode, convert_gamma_value(png_ptr,
356 output_gamma));
357 }
358 # endif
359 #endif
360
361 #ifdef PNG_READ_QUANTIZE_SUPPORTED
362 /* Dither file to 8-bit. Supply a palette, the current number
363 * of elements in the palette, the maximum number of elements
364 * allowed, and a histogram if possible. If the current number
365 * of colors is greater then the maximum number, the palette will be
366 * modified to fit in the maximum number. "full_quantize" indicates
367 * whether we need a quantizing cube set up for RGB images, or if we
368 * simply are reducing the number of colors in a paletted image.
369 */
370
371 typedef struct png_dsort_struct
372 {
373 struct png_dsort_struct FAR * next;
374 png_byte left;
375 png_byte right;
376 } png_dsort;
377 typedef png_dsort FAR * png_dsortp;
378 typedef png_dsort FAR * FAR * png_dsortpp;
379
380 void PNGAPI
381 png_set_quantize(png_structp png_ptr, png_colorp palette,
382 int num_palette, int maximum_colors, png_const_uint_16p histogram,
383 int full_quantize)
384 {
385 png_debug(1, "in png_set_quantize");
386
387 if (png_ptr == NULL)
388 return;
389
390 png_ptr->transformations |= PNG_QUANTIZE;
391
392 if (!full_quantize)
393 {
394 int i;
395
396 png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr,
397 (png_uint_32)(num_palette * png_sizeof(png_byte)));
398 for (i = 0; i < num_palette; i++)
399 png_ptr->quantize_index[i] = (png_byte)i;
400 }
401
402 if (num_palette > maximum_colors)
403 {
404 if (histogram != NULL)
405 {
406 /* This is easy enough, just throw out the least used colors.
407 * Perhaps not the best solution, but good enough.
408 */
409
410 int i;
411
412 /* Initialize an array to sort colors */
413 png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr,
414 (png_uint_32)(num_palette * png_sizeof(png_byte)));
415
416 /* Initialize the quantize_sort array */
417 for (i = 0; i < num_palette; i++)
418 png_ptr->quantize_sort[i] = (png_byte)i;
419
420 /* Find the least used palette entries by starting a
421 * bubble sort, and running it until we have sorted
422 * out enough colors. Note that we don't care about
423 * sorting all the colors, just finding which are
424 * least used.
425 */
426
427 for (i = num_palette - 1; i >= maximum_colors; i--)
428 {
429 int done; /* To stop early if the list is pre-sorted */
430 int j;
431
432 done = 1;
433 for (j = 0; j < i; j++)
434 {
435 if (histogram[png_ptr->quantize_sort[j]]
436 < histogram[png_ptr->quantize_sort[j + 1]])
437 {
438 png_byte t;
439
440 t = png_ptr->quantize_sort[j];
441 png_ptr->quantize_sort[j] = png_ptr->quantize_sort[j + 1];
442 png_ptr->quantize_sort[j + 1] = t;
443 done = 0;
444 }
445 }
446
447 if (done)
448 break;
449 }
450
451 /* Swap the palette around, and set up a table, if necessary */
452 if (full_quantize)
453 {
454 int j = num_palette;
455
456 /* Put all the useful colors within the max, but don't
457 * move the others.
458 */
459 for (i = 0; i < maximum_colors; i++)
460 {
461 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
462 {
463 do
464 j--;
465 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
466
467 palette[i] = palette[j];
468 }
469 }
470 }
471 else
472 {
473 int j = num_palette;
474
475 /* Move all the used colors inside the max limit, and
476 * develop a translation table.
477 */
478 for (i = 0; i < maximum_colors; i++)
479 {
480 /* Only move the colors we need to */
481 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
482 {
483 png_color tmp_color;
484
485 do
486 j--;
487 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
488
489 tmp_color = palette[j];
490 palette[j] = palette[i];
491 palette[i] = tmp_color;
492 /* Indicate where the color went */
493 png_ptr->quantize_index[j] = (png_byte)i;
494 png_ptr->quantize_index[i] = (png_byte)j;
495 }
496 }
497
498 /* Find closest color for those colors we are not using */
499 for (i = 0; i < num_palette; i++)
500 {
501 if ((int)png_ptr->quantize_index[i] >= maximum_colors)
502 {
503 int min_d, k, min_k, d_index;
504
505 /* Find the closest color to one we threw out */
506 d_index = png_ptr->quantize_index[i];
507 min_d = PNG_COLOR_DIST(palette[d_index], palette[0]);
508 for (k = 1, min_k = 0; k < maximum_colors; k++)
509 {
510 int d;
511
512 d = PNG_COLOR_DIST(palette[d_index], palette[k]);
513
514 if (d < min_d)
515 {
516 min_d = d;
517 min_k = k;
518 }
519 }
520 /* Point to closest color */
521 png_ptr->quantize_index[i] = (png_byte)min_k;
522 }
523 }
524 }
525 png_free(png_ptr, png_ptr->quantize_sort);
526 png_ptr->quantize_sort = NULL;
527 }
528 else
529 {
530 /* This is much harder to do simply (and quickly). Perhaps
531 * we need to go through a median cut routine, but those
532 * don't always behave themselves with only a few colors
533 * as input. So we will just find the closest two colors,
534 * and throw out one of them (chosen somewhat randomly).
535 * [We don't understand this at all, so if someone wants to
536 * work on improving it, be our guest - AED, GRP]
537 */
538 int i;
539 int max_d;
540 int num_new_palette;
541 png_dsortp t;
542 png_dsortpp hash;
543
544 t = NULL;
545
546 /* Initialize palette index arrays */
547 png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr,
548 (png_uint_32)(num_palette * png_sizeof(png_byte)));
549 png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr,
550 (png_uint_32)(num_palette * png_sizeof(png_byte)));
551
552 /* Initialize the sort array */
553 for (i = 0; i < num_palette; i++)
554 {
555 png_ptr->index_to_palette[i] = (png_byte)i;
556 png_ptr->palette_to_index[i] = (png_byte)i;
557 }
558
559 hash = (png_dsortpp)png_calloc(png_ptr, (png_uint_32)(769 *
560 png_sizeof(png_dsortp)));
561
562 num_new_palette = num_palette;
563
564 /* Initial wild guess at how far apart the farthest pixel
565 * pair we will be eliminating will be. Larger
566 * numbers mean more areas will be allocated, Smaller
567 * numbers run the risk of not saving enough data, and
568 * having to do this all over again.
569 *
570 * I have not done extensive checking on this number.
571 */
572 max_d = 96;
573
574 while (num_new_palette > maximum_colors)
575 {
576 for (i = 0; i < num_new_palette - 1; i++)
577 {
578 int j;
579
580 for (j = i + 1; j < num_new_palette; j++)
581 {
582 int d;
583
584 d = PNG_COLOR_DIST(palette[i], palette[j]);
585
586 if (d <= max_d)
587 {
588
589 t = (png_dsortp)png_malloc_warn(png_ptr,
590 (png_uint_32)(png_sizeof(png_dsort)));
591
592 if (t == NULL)
593 break;
594
595 t->next = hash[d];
596 t->left = (png_byte)i;
597 t->right = (png_byte)j;
598 hash[d] = t;
599 }
600 }
601 if (t == NULL)
602 break;
603 }
604
605 if (t != NULL)
606 for (i = 0; i <= max_d; i++)
607 {
608 if (hash[i] != NULL)
609 {
610 png_dsortp p;
611
612 for (p = hash[i]; p; p = p->next)
613 {
614 if ((int)png_ptr->index_to_palette[p->left]
615 < num_new_palette &&
616 (int)png_ptr->index_to_palette[p->right]
617 < num_new_palette)
618 {
619 int j, next_j;
620
621 if (num_new_palette & 0x01)
622 {
623 j = p->left;
624 next_j = p->right;
625 }
626 else
627 {
628 j = p->right;
629 next_j = p->left;
630 }
631
632 num_new_palette--;
633 palette[png_ptr->index_to_palette[j]]
634 = palette[num_new_palette];
635 if (!full_quantize)
636 {
637 int k;
638
639 for (k = 0; k < num_palette; k++)
640 {
641 if (png_ptr->quantize_index[k] ==
642 png_ptr->index_to_palette[j])
643 png_ptr->quantize_index[k] =
644 png_ptr->index_to_palette[next_j];
645
646 if ((int)png_ptr->quantize_index[k] ==
647 num_new_palette)
648 png_ptr->quantize_index[k] =
649 png_ptr->index_to_palette[j];
650 }
651 }
652
653 png_ptr->index_to_palette[png_ptr->palette_to_index
654 [num_new_palette]] = png_ptr->index_to_palette[j];
655
656 png_ptr->palette_to_index[png_ptr->index_to_palette[j]]
657 = png_ptr->palette_to_index[num_new_palette];
658
659 png_ptr->index_to_palette[j] =
660 (png_byte)num_new_palette;
661
662 png_ptr->palette_to_index[num_new_palette] =
663 (png_byte)j;
664 }
665 if (num_new_palette <= maximum_colors)
666 break;
667 }
668 if (num_new_palette <= maximum_colors)
669 break;
670 }
671 }
672
673 for (i = 0; i < 769; i++)
674 {
675 if (hash[i] != NULL)
676 {
677 png_dsortp p = hash[i];
678 while (p)
679 {
680 t = p->next;
681 png_free(png_ptr, p);
682 p = t;
683 }
684 }
685 hash[i] = 0;
686 }
687 max_d += 96;
688 }
689 png_free(png_ptr, hash);
690 png_free(png_ptr, png_ptr->palette_to_index);
691 png_free(png_ptr, png_ptr->index_to_palette);
692 png_ptr->palette_to_index = NULL;
693 png_ptr->index_to_palette = NULL;
694 }
695 num_palette = maximum_colors;
696 }
697 if (png_ptr->palette == NULL)
698 {
699 png_ptr->palette = palette;
700 }
701 png_ptr->num_palette = (png_uint_16)num_palette;
702
703 if (full_quantize)
704 {
705 int i;
706 png_bytep distance;
707 int total_bits = PNG_QUANTIZE_RED_BITS + PNG_QUANTIZE_GREEN_BITS +
708 PNG_QUANTIZE_BLUE_BITS;
709 int num_red = (1 << PNG_QUANTIZE_RED_BITS);
710 int num_green = (1 << PNG_QUANTIZE_GREEN_BITS);
711 int num_blue = (1 << PNG_QUANTIZE_BLUE_BITS);
712 png_size_t num_entries = ((png_size_t)1 << total_bits);
713
714 png_ptr->palette_lookup = (png_bytep)png_calloc(png_ptr,
715 (png_uint_32)(num_entries * png_sizeof(png_byte)));
716
717 distance = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_entries *
718 png_sizeof(png_byte)));
719
720 png_memset(distance, 0xff, num_entries * png_sizeof(png_byte));
721
722 for (i = 0; i < num_palette; i++)
723 {
724 int ir, ig, ib;
725 int r = (palette[i].red >> (8 - PNG_QUANTIZE_RED_BITS));
726 int g = (palette[i].green >> (8 - PNG_QUANTIZE_GREEN_BITS));
727 int b = (palette[i].blue >> (8 - PNG_QUANTIZE_BLUE_BITS));
728
729 for (ir = 0; ir < num_red; ir++)
730 {
731 /* int dr = abs(ir - r); */
732 int dr = ((ir > r) ? ir - r : r - ir);
733 int index_r = (ir << (PNG_QUANTIZE_BLUE_BITS +
734 PNG_QUANTIZE_GREEN_BITS));
735
736 for (ig = 0; ig < num_green; ig++)
737 {
738 /* int dg = abs(ig - g); */
739 int dg = ((ig > g) ? ig - g : g - ig);
740 int dt = dr + dg;
741 int dm = ((dr > dg) ? dr : dg);
742 int index_g = index_r | (ig << PNG_QUANTIZE_BLUE_BITS);
743
744 for (ib = 0; ib < num_blue; ib++)
745 {
746 int d_index = index_g | ib;
747 /* int db = abs(ib - b); */
748 int db = ((ib > b) ? ib - b : b - ib);
749 int dmax = ((dm > db) ? dm : db);
750 int d = dmax + dt + db;
751
752 if (d < (int)distance[d_index])
753 {
754 distance[d_index] = (png_byte)d;
755 png_ptr->palette_lookup[d_index] = (png_byte)i;
756 }
757 }
758 }
759 }
760 }
761
762 png_free(png_ptr, distance);
763 }
764 }
765 #endif /* PNG_READ_QUANTIZE_SUPPORTED */
766
767 #ifdef PNG_READ_GAMMA_SUPPORTED
768 void PNGFAPI
769 png_set_gamma_fixed(png_structp png_ptr, png_fixed_point scrn_gamma,
770 png_fixed_point file_gamma)
771 {
772 png_debug(1, "in png_set_gamma_fixed");
773
774 if (png_ptr == NULL)
775 return;
776
777 /* New in libpng-1.5.4 - reserve particular negative values as flags. */
778 scrn_gamma = translate_gamma_flags(png_ptr, scrn_gamma, 1/*screen*/);
779 file_gamma = translate_gamma_flags(png_ptr, file_gamma, 0/*file*/);
780
781 #if PNG_LIBPNG_VER >= 10600
782 /* Checking the gamma values for being >0 was added in 1.5.4 along with the
783 * premultiplied alpha support; this actually hides an undocumented feature
784 * of the previous implementation which allowed gamma processing to be
785 * disabled in background handling. There is no evidence (so far) that this
786 * was being used; however, png_set_background itself accepted and must still
787 * accept '0' for the gamma value it takes, because it isn't always used.
788 *
789 * Since this is an API change (albeit a very minor one that removes an
790 * undocumented API feature) it will not be made until libpng-1.6.0.
791 */
792 if (file_gamma <= 0)
793 png_error(png_ptr, "invalid file gamma in png_set_gamma");
794
795 if (scrn_gamma <= 0)
796 png_error(png_ptr, "invalid screen gamma in png_set_gamma");
797 #endif
798
799 /* Set the gamma values unconditionally - this overrides the value in the PNG
800 * file if a gAMA chunk was present. png_set_alpha_mode provides a
801 * different, easier, way to default the file gamma.
802 */
803 png_ptr->gamma = file_gamma;
804 png_ptr->screen_gamma = scrn_gamma;
805 }
806
807 # ifdef PNG_FLOATING_POINT_SUPPORTED
808 void PNGAPI
809 png_set_gamma(png_structp png_ptr, double scrn_gamma, double file_gamma)
810 {
811 png_set_gamma_fixed(png_ptr, convert_gamma_value(png_ptr, scrn_gamma),
812 convert_gamma_value(png_ptr, file_gamma));
813 }
814 # endif /* FLOATING_POINT_SUPPORTED */
815 #endif /* READ_GAMMA */
816
817 #ifdef PNG_READ_EXPAND_SUPPORTED
818 /* Expand paletted images to RGB, expand grayscale images of
819 * less than 8-bit depth to 8-bit depth, and expand tRNS chunks
820 * to alpha channels.
821 */
822 void PNGAPI
823 png_set_expand(png_structp png_ptr)
824 {
825 png_debug(1, "in png_set_expand");
826
827 if (png_ptr == NULL)
828 return;
829
830 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
831 png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
832 }
833
834 /* GRR 19990627: the following three functions currently are identical
835 * to png_set_expand(). However, it is entirely reasonable that someone
836 * might wish to expand an indexed image to RGB but *not* expand a single,
837 * fully transparent palette entry to a full alpha channel--perhaps instead
838 * convert tRNS to the grayscale/RGB format (16-bit RGB value), or replace
839 * the transparent color with a particular RGB value, or drop tRNS entirely.
840 * IOW, a future version of the library may make the transformations flag
841 * a bit more fine-grained, with separate bits for each of these three
842 * functions.
843 *
844 * More to the point, these functions make it obvious what libpng will be
845 * doing, whereas "expand" can (and does) mean any number of things.
846 *
847 * GRP 20060307: In libpng-1.2.9, png_set_gray_1_2_4_to_8() was modified
848 * to expand only the sample depth but not to expand the tRNS to alpha
849 * and its name was changed to png_set_expand_gray_1_2_4_to_8().
850 */
851
852 /* Expand paletted images to RGB. */
853 void PNGAPI
854 png_set_palette_to_rgb(png_structp png_ptr)
855 {
856 png_debug(1, "in png_set_palette_to_rgb");
857
858 if (png_ptr == NULL)
859 return;
860
861 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
862 png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
863 }
864
865 /* Expand grayscale images of less than 8-bit depth to 8 bits. */
866 void PNGAPI
867 png_set_expand_gray_1_2_4_to_8(png_structp png_ptr)
868 {
869 png_debug(1, "in png_set_expand_gray_1_2_4_to_8");
870
871 if (png_ptr == NULL)
872 return;
873
874 png_ptr->transformations |= PNG_EXPAND;
875 png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
876 }
877
878
879
880 /* Expand tRNS chunks to alpha channels. */
881 void PNGAPI
882 png_set_tRNS_to_alpha(png_structp png_ptr)
883 {
884 png_debug(1, "in png_set_tRNS_to_alpha");
885
886 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
887 png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
888 }
889 #endif /* defined(PNG_READ_EXPAND_SUPPORTED) */
890
891 #ifdef PNG_READ_EXPAND_16_SUPPORTED
892 /* Expand to 16-bit channels, expand the tRNS chunk too (because otherwise
893 * it may not work correctly.)
894 */
895 void PNGAPI
896 png_set_expand_16(png_structp png_ptr)
897 {
898 png_debug(1, "in png_set_expand_16");
899
900 if (png_ptr == NULL)
901 return;
902
903 png_ptr->transformations |= (PNG_EXPAND_16 | PNG_EXPAND | PNG_EXPAND_tRNS);
904 png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
905
906 /* New API, make sure apps call the correct initializers: */
907 png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED;
908 }
909 #endif
910
911 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
912 void PNGAPI
913 png_set_gray_to_rgb(png_structp png_ptr)
914 {
915 png_debug(1, "in png_set_gray_to_rgb");
916
917 if (png_ptr != NULL)
918 {
919 /* Because rgb must be 8 bits or more: */
920 png_set_expand_gray_1_2_4_to_8(png_ptr);
921 png_ptr->transformations |= PNG_GRAY_TO_RGB;
922 png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
923 }
924 }
925 #endif
926
927 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
928 void PNGFAPI
929 png_set_rgb_to_gray_fixed(png_structp png_ptr, int error_action,
930 png_fixed_point red, png_fixed_point green)
931 {
932 png_debug(1, "in png_set_rgb_to_gray");
933
934 if (png_ptr == NULL)
935 return;
936
937 switch(error_action)
938 {
939 case PNG_ERROR_ACTION_NONE:
940 png_ptr->transformations |= PNG_RGB_TO_GRAY;
941 break;
942
943 case PNG_ERROR_ACTION_WARN:
944 png_ptr->transformations |= PNG_RGB_TO_GRAY_WARN;
945 break;
946
947 case PNG_ERROR_ACTION_ERROR:
948 png_ptr->transformations |= PNG_RGB_TO_GRAY_ERR;
949 break;
950
951 default:
952 png_error(png_ptr, "invalid error action to rgb_to_gray");
953 break;
954 }
955 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
956 #ifdef PNG_READ_EXPAND_SUPPORTED
957 png_ptr->transformations |= PNG_EXPAND;
958 #else
959 {
960 png_warning(png_ptr,
961 "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED");
962
963 png_ptr->transformations &= ~PNG_RGB_TO_GRAY;
964 }
965 #endif
966 {
967 if (red >= 0 && green >= 0 && red + green <= PNG_FP_1)
968 {
969 png_uint_16 red_int, green_int;
970
971 /* NOTE: this calculation does not round, but this behavior is retained
972 * for consistency, the inaccuracy is very small. The code here always
973 * overwrites the coefficients, regardless of whether they have been
974 * defaulted or set already.
975 */
976 red_int = (png_uint_16)(((png_uint_32)red*32768)/100000);
977 green_int = (png_uint_16)(((png_uint_32)green*32768)/100000);
978
979 png_ptr->rgb_to_gray_red_coeff = red_int;
980 png_ptr->rgb_to_gray_green_coeff = green_int;
981 png_ptr->rgb_to_gray_coefficients_set = 1;
982 }
983
984 else
985 {
986 if (red >= 0 && green >= 0)
987 png_warning(png_ptr,
988 "ignoring out of range rgb_to_gray coefficients");
989
990 /* Use the defaults, from the cHRM chunk if set, else the historical
991 * values which are close to the sRGB/HDTV/ITU-Rec 709 values. See
992 * png_do_rgb_to_gray for more discussion of the values. In this case
993 * the coefficients are not marked as 'set' and are not overwritten if
994 * something has already provided a default.
995 */
996 if (png_ptr->rgb_to_gray_red_coeff == 0 &&
997 png_ptr->rgb_to_gray_green_coeff == 0)
998 {
999 png_ptr->rgb_to_gray_red_coeff = 6968;
1000 png_ptr->rgb_to_gray_green_coeff = 23434;
1001 /* png_ptr->rgb_to_gray_blue_coeff = 2366; */
1002 }
1003 }
1004 }
1005 }
1006
1007 #ifdef PNG_FLOATING_POINT_SUPPORTED
1008 /* Convert a RGB image to a grayscale of the same width. This allows us,
1009 * for example, to convert a 24 bpp RGB image into an 8 bpp grayscale image.
1010 */
1011
1012 void PNGAPI
1013 png_set_rgb_to_gray(png_structp png_ptr, int error_action, double red,
1014 double green)
1015 {
1016 if (png_ptr == NULL)
1017 return;
1018
1019 png_set_rgb_to_gray_fixed(png_ptr, error_action,
1020 png_fixed(png_ptr, red, "rgb to gray red coefficient"),
1021 png_fixed(png_ptr, green, "rgb to gray green coefficient"));
1022 }
1023 #endif /* FLOATING POINT */
1024
1025 #endif
1026
1027 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
1028 defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
1029 void PNGAPI
1030 png_set_read_user_transform_fn(png_structp png_ptr, png_user_transform_ptr
1031 read_user_transform_fn)
1032 {
1033 png_debug(1, "in png_set_read_user_transform_fn");
1034
1035 if (png_ptr == NULL)
1036 return;
1037
1038 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
1039 png_ptr->transformations |= PNG_USER_TRANSFORM;
1040 png_ptr->read_user_transform_fn = read_user_transform_fn;
1041 #endif
1042 }
1043 #endif
1044
1045 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
1046 #ifdef PNG_READ_GAMMA_SUPPORTED
1047 /* In the case of gamma transformations only do transformations on images where
1048 * the [file] gamma and screen_gamma are not close reciprocals, otherwise it
1049 * slows things down slightly, and also needlessly introduces small errors.
1050 */
1051 static int /* PRIVATE */
1052 png_gamma_threshold(png_fixed_point screen_gamma, png_fixed_point file_gamma)
1053 {
1054 /* PNG_GAMMA_THRESHOLD is the threshold for performing gamma
1055 * correction as a difference of the overall transform from 1.0
1056 *
1057 * We want to compare the threshold with s*f - 1, if we get
1058 * overflow here it is because of wacky gamma values so we
1059 * turn on processing anyway.
1060 */
1061 png_fixed_point gtest;
1062 return !png_muldiv(&gtest, screen_gamma, file_gamma, PNG_FP_1) ||
1063 png_gamma_significant(gtest);
1064 }
1065 #endif
1066
1067 /* Initialize everything needed for the read. This includes modifying
1068 * the palette.
1069 */
1070
1071 /*For the moment 'png_init_palette_transformations' and
1072 * 'png_init_rgb_transformations' only do some flag canceling optimizations.
1073 * The intent is that these two routines should have palette or rgb operations
1074 * extracted from 'png_init_read_transformations'.
1075 */
1076 static void /* PRIVATE */
1077 png_init_palette_transformations(png_structp png_ptr)
1078 {
1079 /* Called to handle the (input) palette case. In png_do_read_transformations
1080 * the first step is to expand the palette if requested, so this code must
1081 * take care to only make changes that are invariant with respect to the
1082 * palette expansion, or only do them if there is no expansion.
1083 *
1084 * STRIP_ALPHA has already been handled in the caller (by setting num_trans
1085 * to 0.)
1086 */
1087 int input_has_alpha = 0;
1088 int input_has_transparency = 0;
1089
1090 if (png_ptr->num_trans > 0)
1091 {
1092 int i;
1093
1094 /* Ignore if all the entries are opaque (unlikely!) */
1095 for (i=0; i<png_ptr->num_trans; ++i)
1096 if (png_ptr->trans_alpha[i] == 255)
1097 continue;
1098 else if (png_ptr->trans_alpha[i] == 0)
1099 input_has_transparency = 1;
1100 else
1101 input_has_alpha = 1;
1102 }
1103
1104 /* If no alpha we can optimize. */
1105 if (!input_has_alpha)
1106 {
1107 /* Any alpha means background and associative alpha processing is
1108 * required, however if the alpha is 0 or 1 throughout OPTIIMIZE_ALPHA
1109 * and ENCODE_ALPHA are irrelevant.
1110 */
1111 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1112 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1113
1114 if (!input_has_transparency)
1115 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1116 }
1117
1118 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1119 /* png_set_background handling - deals with the complexity of whether the
1120 * background color is in the file format or the screen format in the case
1121 * where an 'expand' will happen.
1122 */
1123
1124 /* The following code cannot be entered in the alpha pre-multiplication case
1125 * because PNG_BACKGROUND_EXPAND is cancelled below.
1126 */
1127 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
1128 (png_ptr->transformations & PNG_EXPAND))
1129 {
1130 {
1131 png_ptr->background.red =
1132 png_ptr->palette[png_ptr->background.index].red;
1133 png_ptr->background.green =
1134 png_ptr->palette[png_ptr->background.index].green;
1135 png_ptr->background.blue =
1136 png_ptr->palette[png_ptr->background.index].blue;
1137
1138 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1139 if (png_ptr->transformations & PNG_INVERT_ALPHA)
1140 {
1141 if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
1142 {
1143 /* Invert the alpha channel (in tRNS) unless the pixels are
1144 * going to be expanded, in which case leave it for later
1145 */
1146 int i, istop = png_ptr->num_trans;
1147
1148 for (i=0; i<istop; i++)
1149 png_ptr->trans_alpha[i] = (png_byte)(255 -
1150 png_ptr->trans_alpha[i]);
1151 }
1152 }
1153 #endif /* PNG_READ_INVERT_ALPHA_SUPPORTED */
1154 }
1155 } /* background expand and (therefore) no alpha association. */
1156 #endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */
1157 }
1158
1159 static void /* PRIVATE */
1160 png_init_rgb_transformations(png_structp png_ptr)
1161 {
1162 /* Added to libpng-1.5.4: check the color type to determine whether there
1163 * is any alpha or transparency in the image and simply cancel the
1164 * background and alpha mode stuff if there isn't.
1165 */
1166 int input_has_alpha = (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0;
1167 int input_has_transparency = png_ptr->num_trans > 0;
1168
1169 /* If no alpha we can optimize. */
1170 if (!input_has_alpha)
1171 {
1172 /* Any alpha means background and associative alpha processing is
1173 * required, however if the alpha is 0 or 1 throughout OPTIIMIZE_ALPHA
1174 * and ENCODE_ALPHA are irrelevant.
1175 */
1176 # ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1177 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1178 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1179 # endif
1180
1181 if (!input_has_transparency)
1182 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1183 }
1184
1185 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1186 /* png_set_background handling - deals with the complexity of whether the
1187 * background color is in the file format or the screen format in the case
1188 * where an 'expand' will happen.
1189 */
1190
1191 /* The following code cannot be entered in the alpha pre-multiplication case
1192 * because PNG_BACKGROUND_EXPAND is cancelled below.
1193 */
1194 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
1195 (png_ptr->transformations & PNG_EXPAND) &&
1196 !(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
1197 /* i.e., GRAY or GRAY_ALPHA */
1198 {
1199 {
1200 /* Expand background and tRNS chunks */
1201 int gray = png_ptr->background.gray;
1202 int trans_gray = png_ptr->trans_color.gray;
1203
1204 switch (png_ptr->bit_depth)
1205 {
1206 case 1:
1207 gray *= 0xff;
1208 trans_gray *= 0xff;
1209 break;
1210
1211 case 2:
1212 gray *= 0x55;
1213 trans_gray *= 0x55;
1214 break;
1215
1216 case 4:
1217 gray *= 0x11;
1218 trans_gray *= 0x11;
1219 break;
1220
1221 default:
1222
1223 case 8:
1224 /* FALL THROUGH (already 8 bits) */
1225
1226 case 16:
1227 /* Already a full 16 bits */
1228 break;
1229 }
1230
1231 png_ptr->background.red = png_ptr->background.green =
1232 png_ptr->background.blue = (png_uint_16)gray;
1233
1234 if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
1235 {
1236 png_ptr->trans_color.red = png_ptr->trans_color.green =
1237 png_ptr->trans_color.blue = (png_uint_16)trans_gray;
1238 }
1239 }
1240 } /* background expand and (therefore) no alpha association. */
1241 #endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */
1242 }
1243
1244 void /* PRIVATE */
1245 png_init_read_transformations(png_structp png_ptr)
1246 {
1247 png_debug(1, "in png_init_read_transformations");
1248
1249 /* This internal function is called from png_read_start_row in pngrutil.c
1250 * and it is called before the 'rowbytes' calculation is done, so the code
1251 * in here can change or update the transformations flags.
1252 *
1253 * First do updates that do not depend on the details of the PNG image data
1254 * being processed.
1255 */
1256
1257 #ifdef PNG_READ_GAMMA_SUPPORTED
1258 /* Prior to 1.5.4 these tests were performed from png_set_gamma, 1.5.4 adds
1259 * png_set_alpha_mode and this is another source for a default file gamma so
1260 * the test needs to be performed later - here. In addition prior to 1.5.4
1261 * the tests were repeated for the PALETTE color type here - this is no
1262 * longer necessary (and doesn't seem to have been necessary before.)
1263 */
1264 {
1265 /* The following temporary indicates if overall gamma correction is
1266 * required.
1267 */
1268 int gamma_correction = 0;
1269
1270 if (png_ptr->gamma != 0) /* has been set */
1271 {
1272 if (png_ptr->screen_gamma != 0) /* screen set too */
1273 gamma_correction = png_gamma_threshold(png_ptr->gamma,
1274 png_ptr->screen_gamma);
1275
1276 else
1277 /* Assume the output matches the input; a long time default behavior
1278 * of libpng, although the standard has nothing to say about this.
1279 */
1280 png_ptr->screen_gamma = png_reciprocal(png_ptr->gamma);
1281 }
1282
1283 else if (png_ptr->screen_gamma != 0)
1284 /* The converse - assume the file matches the screen, note that this
1285 * perhaps undesireable default can (from 1.5.4) be changed by calling
1286 * png_set_alpha_mode (even if the alpha handling mode isn't required
1287 * or isn't changed from the default.)
1288 */
1289 png_ptr->gamma = png_reciprocal(png_ptr->screen_gamma);
1290
1291 else /* neither are set */
1292 /* Just in case the following prevents any processing - file and screen
1293 * are both assumed to be linear and there is no way to introduce a
1294 * third gamma value other than png_set_background with 'UNIQUE', and,
1295 * prior to 1.5.4
1296 */
1297 png_ptr->screen_gamma = png_ptr->gamma = PNG_FP_1;
1298
1299 /* Now turn the gamma transformation on or off as appropriate. Notice
1300 * that PNG_GAMMA just refers to the file->screen correction. Alpha
1301 * composition may independently cause gamma correction because it needs
1302 * linear data (e.g. if the file has a gAMA chunk but the screen gamma
1303 * hasn't been specified.) In any case this flag may get turned off in
1304 * the code immediately below if the transform can be handled outside the
1305 * row loop.
1306 */
1307 if (gamma_correction)
1308 png_ptr->transformations |= PNG_GAMMA;
1309
1310 else
1311 png_ptr->transformations &= ~PNG_GAMMA;
1312 }
1313 #endif
1314
1315 /* Certain transformations have the effect of preventing other
1316 * transformations that happen afterward in png_do_read_transformations,
1317 * resolve the interdependencies here. From the code of
1318 * png_do_read_transformations the order is:
1319 *
1320 * 1) PNG_EXPAND (including PNG_EXPAND_tRNS)
1321 * 2) PNG_STRIP_ALPHA (if no compose)
1322 * 3) PNG_RGB_TO_GRAY
1323 * 4) PNG_GRAY_TO_RGB iff !PNG_BACKGROUND_IS_GRAY
1324 * 5) PNG_COMPOSE
1325 * 6) PNG_GAMMA
1326 * 7) PNG_STRIP_ALPHA (if compose)
1327 * 8) PNG_ENCODE_ALPHA
1328 * 9) PNG_SCALE_16_TO_8
1329 * 10) PNG_16_TO_8
1330 * 11) PNG_QUANTIZE (converts to palette)
1331 * 12) PNG_EXPAND_16
1332 * 13) PNG_GRAY_TO_RGB iff PNG_BACKGROUND_IS_GRAY
1333 * 14) PNG_INVERT_MONO
1334 * 15) PNG_SHIFT
1335 * 16) PNG_PACK
1336 * 17) PNG_BGR
1337 * 18) PNG_PACKSWAP
1338 * 19) PNG_FILLER (includes PNG_ADD_ALPHA)
1339 * 20) PNG_INVERT_ALPHA
1340 * 21) PNG_SWAP_ALPHA
1341 * 22) PNG_SWAP_BYTES
1342 * 23) PNG_USER_TRANSFORM [must be last]
1343 */
1344 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1345 if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
1346 !(png_ptr->transformations & PNG_COMPOSE))
1347 {
1348 /* Stripping the alpha channel happens immediately after the 'expand'
1349 * transformations, before all other transformation, so it cancels out
1350 * the alpha handling. It has the side effect negating the effect of
1351 * PNG_EXPAND_tRNS too:
1352 */
1353 png_ptr->transformations &= ~(PNG_BACKGROUND_EXPAND | PNG_ENCODE_ALPHA |
1354 PNG_EXPAND_tRNS);
1355 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1356
1357 /* Kill the tRNS chunk itself too. Prior to 1.5.4 this did not happen
1358 * so transparency information would remain just so long as it wasn't
1359 * expanded. This produces unexpected API changes if the set of things
1360 * that do PNG_EXPAND_tRNS changes (perfectly possible given the
1361 * documentation - which says ask for what you want, accept what you
1362 * get.) This makes the behavior consistent from 1.5.4:
1363 */
1364 png_ptr->num_trans = 0;
1365 }
1366 #endif /* STRIP_ALPHA supported, no COMPOSE */
1367
1368 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1369 /* If the screen gamma is about 1.0 then the OPTIMIZE_ALPHA and ENCODE_ALPHA
1370 * settings will have no effect.
1371 */
1372 if (!png_gamma_significant(png_ptr->screen_gamma))
1373 {
1374 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1375 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1376 }
1377 #endif
1378
1379 #if defined(PNG_READ_EXPAND_SUPPORTED) && \
1380 defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1381 defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
1382 /* Detect gray background and attempt to enable optimization for
1383 * gray --> RGB case.
1384 *
1385 * Note: if PNG_BACKGROUND_EXPAND is set and color_type is either RGB or
1386 * RGB_ALPHA (in which case need_expand is superfluous anyway), the
1387 * background color might actually be gray yet not be flagged as such.
1388 * This is not a problem for the current code, which uses
1389 * PNG_BACKGROUND_IS_GRAY only to decide when to do the
1390 * png_do_gray_to_rgb() transformation.
1391 *
1392 * TODO: this code needs to be revised to avoid the complexity and
1393 * interdependencies. The color type of the background should be recorded in
1394 * png_set_background, along with the bit depth, then the code has a record
1395 * of exactly what color space the background is currently in.
1396 */
1397 if (png_ptr->transformations & PNG_BACKGROUND_EXPAND)
1398 {
1399 /* PNG_BACKGROUND_EXPAND: the background is in the file color space, so if
1400 * the file was grayscale the background value is gray.
1401 */
1402 if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
1403 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1404 }
1405
1406 else if (png_ptr->transformations & PNG_COMPOSE)
1407 {
1408 /* PNG_COMPOSE: png_set_background was called with need_expand false,
1409 * so the color is in the color space of the output or png_set_alpha_mode
1410 * was called and the color is black. Ignore RGB_TO_GRAY because that
1411 * happens before GRAY_TO_RGB.
1412 */
1413 if (png_ptr->transformations & PNG_GRAY_TO_RGB)
1414 {
1415 if (png_ptr->background.red == png_ptr->background.green &&
1416 png_ptr->background.red == png_ptr->background.blue)
1417 {
1418 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1419 png_ptr->background.gray = png_ptr->background.red;
1420 }
1421 }
1422 }
1423 #endif /* PNG_READ_GRAY_TO_RGB_SUPPORTED (etc) */
1424
1425 /* For indexed PNG data (PNG_COLOR_TYPE_PALETTE) many of the transformations
1426 * can be performed directly on the palette, and some (such as rgb to gray)
1427 * can be optimized inside the palette. This is particularly true of the
1428 * composite (background and alpha) stuff, which can be pretty much all done
1429 * in the palette even if the result is expanded to RGB or gray afterward.
1430 *
1431 * NOTE: this is Not Yet Implemented, the code behaves as in 1.5.1 and
1432 * earlier and the palette stuff is actually handled on the first row. This
1433 * leads to the reported bug that the palette returned by png_get_PLTE is not
1434 * updated.
1435 */
1436 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1437 png_init_palette_transformations(png_ptr);
1438
1439 else
1440 png_init_rgb_transformations(png_ptr);
1441
1442 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1443 defined(PNG_READ_EXPAND_16_SUPPORTED)
1444 if ((png_ptr->transformations & PNG_EXPAND_16) &&
1445 (png_ptr->transformations & PNG_COMPOSE) &&
1446 !(png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
1447 png_ptr->bit_depth != 16)
1448 {
1449 /* TODO: fix this. Because the expand_16 operation is after the compose
1450 * handling the background color must be 8, not 16, bits deep, but the
1451 * application will supply a 16-bit value so reduce it here.
1452 *
1453 * The PNG_BACKGROUND_EXPAND code above does not expand to 16 bits at
1454 * present, so that case is ok (until do_expand_16 is moved.)
1455 *
1456 * NOTE: this discards the low 16 bits of the user supplied background
1457 * color, but until expand_16 works properly there is no choice!
1458 */
1459 # define CHOP(x) (x)=((png_uint_16)(((png_uint_32)(x)*255+32895) >> 16))
1460 CHOP(png_ptr->background.red);
1461 CHOP(png_ptr->background.green);
1462 CHOP(png_ptr->background.blue);
1463 CHOP(png_ptr->background.gray);
1464 # undef CHOP
1465 }
1466 #endif /* PNG_READ_BACKGROUND_SUPPORTED && PNG_READ_EXPAND_16_SUPPORTED */
1467
1468 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1469 (defined(PNG_READ_SCALE_16_TO_8_SUPPORTED) || \
1470 defined(PNG_READ_STRIP_16_TO_8_SUPPORTED))
1471 if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) &&
1472 (png_ptr->transformations & PNG_COMPOSE) &&
1473 !(png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
1474 png_ptr->bit_depth == 16)
1475 {
1476 /* On the other hand, if a 16-bit file is to be reduced to 8-bits per
1477 * component this will also happen after PNG_COMPOSE and so the background
1478 * color must be pre-expanded here.
1479 *
1480 * TODO: fix this too.
1481 */
1482 png_ptr->background.red = (png_uint_16)(png_ptr->background.red * 257);
1483 png_ptr->background.green =
1484 (png_uint_16)(png_ptr->background.green * 257);
1485 png_ptr->background.blue = (png_uint_16)(png_ptr->background.blue * 257);
1486 png_ptr->background.gray = (png_uint_16)(png_ptr->background.gray * 257);
1487 }
1488 #endif
1489
1490 /* NOTE: below 'PNG_READ_ALPHA_MODE_SUPPORTED' is presumed to also enable the
1491 * background support (see the comments in scripts/pnglibconf.dfa), this
1492 * allows pre-multiplication of the alpha channel to be implemented as
1493 * compositing on black. This is probably sub-optimal and has been done in
1494 * 1.5.4 betas simply to enable external critique and testing (i.e. to
1495 * implement the new API quickly, without lots of internal changes.)
1496 */
1497
1498 #ifdef PNG_READ_GAMMA_SUPPORTED
1499 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1500 /* Includes ALPHA_MODE */
1501 png_ptr->background_1 = png_ptr->background;
1502 # endif
1503
1504 /* This needs to change - in the palette image case a whole set of tables are
1505 * built when it would be quicker to just calculate the correct value for
1506 * each palette entry directly. Also, the test is too tricky - why check
1507 * PNG_RGB_TO_GRAY if PNG_GAMMA is not set? The answer seems to be that
1508 * PNG_GAMMA is cancelled even if the gamma is known? The test excludes the
1509 * PNG_COMPOSE case, so apparently if there is no *overall* gamma correction
1510 * the gamma tables will not be built even if composition is required on a
1511 * gamma encoded value.
1512 *
1513 * In 1.5.4 this is addressed below by an additional check on the individual
1514 * file gamma - if it is not 1.0 both RGB_TO_GRAY and COMPOSE need the
1515 * tables.
1516 */
1517 if ((png_ptr->transformations & PNG_GAMMA)
1518 || ((png_ptr->transformations & PNG_RGB_TO_GRAY)
1519 && (png_gamma_significant(png_ptr->gamma) ||
1520 png_gamma_significant(png_ptr->screen_gamma)))
1521 || ((png_ptr->transformations & PNG_COMPOSE)
1522 && (png_gamma_significant(png_ptr->gamma)
1523 || png_gamma_significant(png_ptr->screen_gamma)
1524 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1525 || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE
1526 && png_gamma_significant(png_ptr->background_gamma))
1527 # endif
1528 )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA)
1529 && png_gamma_significant(png_ptr->screen_gamma))
1530 )
1531 {
1532 png_build_gamma_table(png_ptr, png_ptr->bit_depth);
1533
1534 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1535 if (png_ptr->transformations & PNG_COMPOSE)
1536 {
1537 /* Issue a warning about this combination: because RGB_TO_GRAY is
1538 * optimized to do the gamma transform if present yet do_background has
1539 * to do the same thing if both options are set a
1540 * double-gamma-correction happens. This is true in all versions of
1541 * libpng to date.
1542 */
1543 if (png_ptr->transformations & PNG_RGB_TO_GRAY)
1544 png_warning(png_ptr,
1545 "libpng does not support gamma+background+rgb_to_gray");
1546
1547 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1548 {
1549 /* We don't get to here unless there is a tRNS chunk with non-opaque
1550 * entries - see the checking code at the start of this function.
1551 */
1552 png_color back, back_1;
1553 png_colorp palette = png_ptr->palette;
1554 int num_palette = png_ptr->num_palette;
1555 int i;
1556 if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_FILE)
1557 {
1558
1559 back.red = png_ptr->gamma_table[png_ptr->background.red];
1560 back.green = png_ptr->gamma_table[png_ptr->background.green];
1561 back.blue = png_ptr->gamma_table[png_ptr->background.blue];
1562
1563 back_1.red = png_ptr->gamma_to_1[png_ptr->background.red];
1564 back_1.green = png_ptr->gamma_to_1[png_ptr->background.green];
1565 back_1.blue = png_ptr->gamma_to_1[png_ptr->background.blue];
1566 }
1567 else
1568 {
1569 png_fixed_point g, gs;
1570
1571 switch (png_ptr->background_gamma_type)
1572 {
1573 case PNG_BACKGROUND_GAMMA_SCREEN:
1574 g = (png_ptr->screen_gamma);
1575 gs = PNG_FP_1;
1576 break;
1577
1578 case PNG_BACKGROUND_GAMMA_FILE:
1579 g = png_reciprocal(png_ptr->gamma);
1580 gs = png_reciprocal2(png_ptr->gamma,
1581 png_ptr->screen_gamma);
1582 break;
1583
1584 case PNG_BACKGROUND_GAMMA_UNIQUE:
1585 g = png_reciprocal(png_ptr->background_gamma);
1586 gs = png_reciprocal2(png_ptr->background_gamma,
1587 png_ptr->screen_gamma);
1588 break;
1589 default:
1590 g = PNG_FP_1; /* back_1 */
1591 gs = PNG_FP_1; /* back */
1592 break;
1593 }
1594
1595 if (png_gamma_significant(gs))
1596 {
1597 back.red = png_gamma_8bit_correct(png_ptr->background.red,
1598 gs);
1599 back.green = png_gamma_8bit_correct(png_ptr->background.green,
1600 gs);
1601 back.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1602 gs);
1603 }
1604
1605 else
1606 {
1607 back.red = (png_byte)png_ptr->background.red;
1608 back.green = (png_byte)png_ptr->background.green;
1609 back.blue = (png_byte)png_ptr->background.blue;
1610 }
1611
1612 if (png_gamma_significant(g))
1613 {
1614 back_1.red = png_gamma_8bit_correct(png_ptr->background.red,
1615 g);
1616 back_1.green = png_gamma_8bit_correct(
1617 png_ptr->background.green, g);
1618 back_1.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1619 g);
1620 }
1621
1622 else
1623 {
1624 back_1.red = (png_byte)png_ptr->background.red;
1625 back_1.green = (png_byte)png_ptr->background.green;
1626 back_1.blue = (png_byte)png_ptr->background.blue;
1627 }
1628 }
1629
1630 for (i = 0; i < num_palette; i++)
1631 {
1632 if (i < (int)png_ptr->num_trans &&
1633 png_ptr->trans_alpha[i] != 0xff)
1634 {
1635 if (png_ptr->trans_alpha[i] == 0)
1636 {
1637 palette[i] = back;
1638 }
1639 else /* if (png_ptr->trans_alpha[i] != 0xff) */
1640 {
1641 png_byte v, w;
1642
1643 v = png_ptr->gamma_to_1[palette[i].red];
1644 png_composite(w, v, png_ptr->trans_alpha[i], back_1.red);
1645 palette[i].red = png_ptr->gamma_from_1[w];
1646
1647 v = png_ptr->gamma_to_1[palette[i].green];
1648 png_composite(w, v, png_ptr->trans_alpha[i], back_1.green);
1649 palette[i].green = png_ptr->gamma_from_1[w];
1650
1651 v = png_ptr->gamma_to_1[palette[i].blue];
1652 png_composite(w, v, png_ptr->trans_alpha[i], back_1.blue);
1653 palette[i].blue = png_ptr->gamma_from_1[w];
1654 }
1655 }
1656 else
1657 {
1658 palette[i].red = png_ptr->gamma_table[palette[i].red];
1659 palette[i].green = png_ptr->gamma_table[palette[i].green];
1660 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1661 }
1662 }
1663
1664 /* Prevent the transformations being done again.
1665 *
1666 * NOTE: this is highly dubious; it removes the transformations in
1667 * place. This seems inconsistent with the general treatment of the
1668 * transformations elsewhere.
1669 */
1670 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_GAMMA);
1671 } /* color_type == PNG_COLOR_TYPE_PALETTE */
1672
1673 /* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */
1674 else /* color_type != PNG_COLOR_TYPE_PALETTE */
1675 {
1676 int gs_sig, g_sig;
1677 png_fixed_point g = PNG_FP_1; /* Correction to linear */
1678 png_fixed_point gs = PNG_FP_1; /* Correction to screen */
1679
1680 switch (png_ptr->background_gamma_type)
1681 {
1682 case PNG_BACKGROUND_GAMMA_SCREEN:
1683 g = png_ptr->screen_gamma;
1684 /* gs = PNG_FP_1; */
1685 break;
1686
1687 case PNG_BACKGROUND_GAMMA_FILE:
1688 g = png_reciprocal(png_ptr->gamma);
1689 gs = png_reciprocal2(png_ptr->gamma, png_ptr->screen_gamma);
1690 break;
1691
1692 case PNG_BACKGROUND_GAMMA_UNIQUE:
1693 g = png_reciprocal(png_ptr->background_gamma);
1694 gs = png_reciprocal2(png_ptr->background_gamma,
1695 png_ptr->screen_gamma);
1696 break;
1697
1698 default:
1699 png_error(png_ptr, "invalid background gamma type");
1700 }
1701
1702 g_sig = png_gamma_significant(g);
1703 gs_sig = png_gamma_significant(gs);
1704
1705 if (g_sig)
1706 png_ptr->background_1.gray = png_gamma_correct(png_ptr,
1707 png_ptr->background.gray, g);
1708
1709 if (gs_sig)
1710 png_ptr->background.gray = png_gamma_correct(png_ptr,
1711 png_ptr->background.gray, gs);
1712
1713 if ((png_ptr->background.red != png_ptr->background.green) ||
1714 (png_ptr->background.red != png_ptr->background.blue) ||
1715 (png_ptr->background.red != png_ptr->background.gray))
1716 {
1717 /* RGB or RGBA with color background */
1718 if (g_sig)
1719 {
1720 png_ptr->background_1.red = png_gamma_correct(png_ptr,
1721 png_ptr->background.red, g);
1722
1723 png_ptr->background_1.green = png_gamma_correct(png_ptr,
1724 png_ptr->background.green, g);
1725
1726 png_ptr->background_1.blue = png_gamma_correct(png_ptr,
1727 png_ptr->background.blue, g);
1728 }
1729
1730 if (gs_sig)
1731 {
1732 png_ptr->background.red = png_gamma_correct(png_ptr,
1733 png_ptr->background.red, gs);
1734
1735 png_ptr->background.green = png_gamma_correct(png_ptr,
1736 png_ptr->background.green, gs);
1737
1738 png_ptr->background.blue = png_gamma_correct(png_ptr,
1739 png_ptr->background.blue, gs);
1740 }
1741 }
1742
1743 else
1744 {
1745 /* GRAY, GRAY ALPHA, RGB, or RGBA with gray background */
1746 png_ptr->background_1.red = png_ptr->background_1.green
1747 = png_ptr->background_1.blue = png_ptr->background_1.gray;
1748
1749 png_ptr->background.red = png_ptr->background.green
1750 = png_ptr->background.blue = png_ptr->background.gray;
1751 }
1752
1753 /* The background is now in screen gamma: */
1754 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_SCREEN;
1755 } /* color_type != PNG_COLOR_TYPE_PALETTE */
1756 }/* png_ptr->transformations & PNG_BACKGROUND */
1757
1758 else
1759 /* Transformation does not include PNG_BACKGROUND */
1760 #endif /* PNG_READ_BACKGROUND_SUPPORTED */
1761 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE
1762 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1763 /* RGB_TO_GRAY needs to have non-gamma-corrected values! */
1764 && ((png_ptr->transformations & PNG_EXPAND) == 0 ||
1765 (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
1766 #endif
1767 )
1768 {
1769 png_colorp palette = png_ptr->palette;
1770 int num_palette = png_ptr->num_palette;
1771 int i;
1772
1773 /* NOTE: there are other transformations that should probably be in
1774 * here too.
1775 */
1776 for (i = 0; i < num_palette; i++)
1777 {
1778 palette[i].red = png_ptr->gamma_table[palette[i].red];
1779 palette[i].green = png_ptr->gamma_table[palette[i].green];
1780 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1781 }
1782
1783 /* Done the gamma correction. */
1784 png_ptr->transformations &= ~PNG_GAMMA;
1785 } /* color_type == PALETTE && !PNG_BACKGROUND transformation */
1786 }
1787 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1788 else
1789 #endif
1790 #endif /* PNG_READ_GAMMA_SUPPORTED */
1791
1792 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1793 /* No GAMMA transformation (see the hanging else 4 lines above) */
1794 if ((png_ptr->transformations & PNG_COMPOSE) &&
1795 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1796 {
1797 int i;
1798 int istop = (int)png_ptr->num_trans;
1799 png_color back;
1800 png_colorp palette = png_ptr->palette;
1801
1802 back.red = (png_byte)png_ptr->background.red;
1803 back.green = (png_byte)png_ptr->background.green;
1804 back.blue = (png_byte)png_ptr->background.blue;
1805
1806 for (i = 0; i < istop; i++)
1807 {
1808 if (png_ptr->trans_alpha[i] == 0)
1809 {
1810 palette[i] = back;
1811 }
1812
1813 else if (png_ptr->trans_alpha[i] != 0xff)
1814 {
1815 /* The png_composite() macro is defined in png.h */
1816 png_composite(palette[i].red, palette[i].red,
1817 png_ptr->trans_alpha[i], back.red);
1818
1819 png_composite(palette[i].green, palette[i].green,
1820 png_ptr->trans_alpha[i], back.green);
1821
1822 png_composite(palette[i].blue, palette[i].blue,
1823 png_ptr->trans_alpha[i], back.blue);
1824 }
1825 }
1826
1827 png_ptr->transformations &= ~PNG_COMPOSE;
1828 }
1829 #endif /* PNG_READ_BACKGROUND_SUPPORTED */
1830
1831 #ifdef PNG_READ_SHIFT_SUPPORTED
1832 if ((png_ptr->transformations & PNG_SHIFT) &&
1833 !(png_ptr->transformations & PNG_EXPAND) &&
1834 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1835 {
1836 int i;
1837 int istop = png_ptr->num_palette;
1838 int shift = 8 - png_ptr->sig_bit.red;
1839
1840 png_ptr->transformations &= ~PNG_SHIFT;
1841
1842 /* significant bits can be in the range 1 to 7 for a meaninful result, if
1843 * the number of significant bits is 0 then no shift is done (this is an
1844 * error condition which is silently ignored.)
1845 */
1846 if (shift > 0 && shift < 8) for (i=0; i<istop; ++i)
1847 {
1848 int component = png_ptr->palette[i].red;
1849
1850 component >>= shift;
1851 png_ptr->palette[i].red = (png_byte)component;
1852 }
1853
1854 shift = 8 - png_ptr->sig_bit.green;
1855 if (shift > 0 && shift < 8) for (i=0; i<istop; ++i)
1856 {
1857 int component = png_ptr->palette[i].green;
1858
1859 component >>= shift;
1860 png_ptr->palette[i].green = (png_byte)component;
1861 }
1862
1863 shift = 8 - png_ptr->sig_bit.blue;
1864 if (shift > 0 && shift < 8) for (i=0; i<istop; ++i)
1865 {
1866 int component = png_ptr->palette[i].blue;
1867
1868 component >>= shift;
1869 png_ptr->palette[i].blue = (png_byte)component;
1870 }
1871 }
1872 #endif /* PNG_READ_SHIFT_SUPPORTED */
1873 }
1874
1875 /* Modify the info structure to reflect the transformations. The
1876 * info should be updated so a PNG file could be written with it,
1877 * assuming the transformations result in valid PNG data.
1878 */
1879 void /* PRIVATE */
1880 png_read_transform_info(png_structp png_ptr, png_infop info_ptr)
1881 {
1882 png_debug(1, "in png_read_transform_info");
1883
1884 #ifdef PNG_READ_EXPAND_SUPPORTED
1885 if (png_ptr->transformations & PNG_EXPAND)
1886 {
1887 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1888 {
1889 /* This check must match what actually happens in
1890 * png_do_expand_palette; if it ever checks the tRNS chunk to see if
1891 * it is all opaque we must do the same (at present it does not.)
1892 */
1893 if (png_ptr->num_trans > 0)
1894 info_ptr->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
1895
1896 else
1897 info_ptr->color_type = PNG_COLOR_TYPE_RGB;
1898
1899 info_ptr->bit_depth = 8;
1900 info_ptr->num_trans = 0;
1901 }
1902 else
1903 {
1904 if (png_ptr->num_trans)
1905 {
1906 if (png_ptr->transformations & PNG_EXPAND_tRNS)
1907 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
1908 }
1909 if (info_ptr->bit_depth < 8)
1910 info_ptr->bit_depth = 8;
1911
1912 info_ptr->num_trans = 0;
1913 }
1914 }
1915 #endif
1916
1917 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
1918 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
1919 /* The following is almost certainly wrong unless the background value is in
1920 * the screen space!
1921 */
1922 if (png_ptr->transformations & PNG_COMPOSE)
1923 info_ptr->background = png_ptr->background;
1924 #endif
1925
1926 #ifdef PNG_READ_GAMMA_SUPPORTED
1927 /* The following used to be conditional on PNG_GAMMA (prior to 1.5.4),
1928 * however it seems that the code in png_init_read_transformations, which has
1929 * been called before this from png_read_update_info->png_read_start_row
1930 * sometimes does the gamma transform and cancels the flag.
1931 */
1932 info_ptr->gamma = png_ptr->gamma;
1933 #endif
1934
1935 if (info_ptr->bit_depth == 16)
1936 {
1937 # ifdef PNG_READ_16BIT_SUPPORTED
1938 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1939 if (png_ptr->transformations & PNG_SCALE_16_TO_8)
1940 info_ptr->bit_depth = 8;
1941 # endif
1942
1943 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1944 if (png_ptr->transformations & PNG_16_TO_8)
1945 info_ptr->bit_depth = 8;
1946 # endif
1947
1948 # else
1949 /* No 16 bit support: force chopping 16-bit input down to 8, in this case
1950 * the app program can chose if both APIs are available by setting the
1951 * correct scaling to use.
1952 */
1953 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1954 /* For compatibility with previous versions use the strip method by
1955 * default. This code works because if PNG_SCALE_16_TO_8 is already
1956 * set the code below will do that in preference to the chop.
1957 */
1958 png_ptr->transformations |= PNG_16_TO_8;
1959 info_ptr->bit_depth = 8;
1960 # else
1961
1962 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1963 png_ptr->transformations |= PNG_SCALE_16_TO_8;
1964 info_ptr->bit_depth = 8;
1965 # else
1966
1967 CONFIGURATION ERROR: you must enable at least one 16 to 8 method
1968 # endif
1969 # endif
1970 #endif /* !READ_16BIT_SUPPORTED */
1971 }
1972
1973 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1974 if (png_ptr->transformations & PNG_GRAY_TO_RGB)
1975 info_ptr->color_type = (png_byte)(info_ptr->color_type |
1976 PNG_COLOR_MASK_COLOR);
1977 #endif
1978
1979 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1980 if (png_ptr->transformations & PNG_RGB_TO_GRAY)
1981 info_ptr->color_type = (png_byte)(info_ptr->color_type &
1982 ~PNG_COLOR_MASK_COLOR);
1983 #endif
1984
1985 #ifdef PNG_READ_QUANTIZE_SUPPORTED
1986 if (png_ptr->transformations & PNG_QUANTIZE)
1987 {
1988 if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
1989 (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) &&
1990 png_ptr->palette_lookup && info_ptr->bit_depth == 8)
1991 {
1992 info_ptr->color_type = PNG_COLOR_TYPE_PALETTE;
1993 }
1994 }
1995 #endif
1996
1997 #ifdef PNG_READ_EXPAND_16_SUPPORTED
1998 if (png_ptr->transformations & PNG_EXPAND_16 && info_ptr->bit_depth == 8 &&
1999 info_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
2000 {
2001 info_ptr->bit_depth = 16;
2002 }
2003 #endif
2004
2005 #ifdef PNG_READ_PACK_SUPPORTED
2006 if ((png_ptr->transformations & PNG_PACK) && (info_ptr->bit_depth < 8))
2007 info_ptr->bit_depth = 8;
2008 #endif
2009
2010 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
2011 info_ptr->channels = 1;
2012
2013 else if (info_ptr->color_type & PNG_COLOR_MASK_COLOR)
2014 info_ptr->channels = 3;
2015
2016 else
2017 info_ptr->channels = 1;
2018
2019 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
2020 if (png_ptr->transformations & PNG_STRIP_ALPHA)
2021 {
2022 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2023 ~PNG_COLOR_MASK_ALPHA);
2024 info_ptr->num_trans = 0;
2025 }
2026 #endif
2027
2028 if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA)
2029 info_ptr->channels++;
2030
2031 #ifdef PNG_READ_FILLER_SUPPORTED
2032 /* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */
2033 if ((png_ptr->transformations & PNG_FILLER) &&
2034 ((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
2035 (info_ptr->color_type == PNG_COLOR_TYPE_GRAY)))
2036 {
2037 info_ptr->channels++;
2038 /* If adding a true alpha channel not just filler */
2039 if (png_ptr->transformations & PNG_ADD_ALPHA)
2040 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
2041 }
2042 #endif
2043
2044 #if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \
2045 defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
2046 if (png_ptr->transformations & PNG_USER_TRANSFORM)
2047 {
2048 if (info_ptr->bit_depth < png_ptr->user_transform_depth)
2049 info_ptr->bit_depth = png_ptr->user_transform_depth;
2050
2051 if (info_ptr->channels < png_ptr->user_transform_channels)
2052 info_ptr->channels = png_ptr->user_transform_channels;
2053 }
2054 #endif
2055
2056 info_ptr->pixel_depth = (png_byte)(info_ptr->channels *
2057 info_ptr->bit_depth);
2058
2059 info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, info_ptr->width);
2060
2061 /* Adding in 1.5.4: cache the above value in png_struct so that we can later
2062 * check in png_rowbytes that the user buffer won't get overwritten. Note
2063 * that the field is not always set - if png_read_update_info isn't called
2064 * the application has to either not do any transforms or get the calculation
2065 * right itself.
2066 */
2067 png_ptr->info_rowbytes = info_ptr->rowbytes;
2068
2069 #ifndef PNG_READ_EXPAND_SUPPORTED
2070 if (png_ptr)
2071 return;
2072 #endif
2073 }
2074
2075 /* Transform the row. The order of transformations is significant,
2076 * and is very touchy. If you add a transformation, take care to
2077 * decide how it fits in with the other transformations here.
2078 */
2079 void /* PRIVATE */
2080 png_do_read_transformations(png_structp png_ptr, png_row_infop row_info)
2081 {
2082 png_debug(1, "in png_do_read_transformations");
2083
2084 if (png_ptr->row_buf == NULL)
2085 {
2086 /* Prior to 1.5.4 this output row/pass where the NULL pointer is, but this
2087 * error is incredibly rare and incredibly easy to debug without this
2088 * information.
2089 */
2090 png_error(png_ptr, "NULL row buffer");
2091 }
2092
2093 /* The following is debugging; prior to 1.5.4 the code was never compiled in;
2094 * in 1.5.4 PNG_FLAG_DETECT_UNINITIALIZED was added and the macro
2095 * PNG_WARN_UNINITIALIZED_ROW removed. In 1.5 the new flag is set only for
2096 * selected new APIs to ensure that there is no API change.
2097 */
2098 if ((png_ptr->flags & PNG_FLAG_DETECT_UNINITIALIZED) != 0 &&
2099 !(png_ptr->flags & PNG_FLAG_ROW_INIT))
2100 {
2101 /* Application has failed to call either png_read_start_image() or
2102 * png_read_update_info() after setting transforms that expand pixels.
2103 * This check added to libpng-1.2.19 (but not enabled until 1.5.4).
2104 */
2105 png_error(png_ptr, "Uninitialized row");
2106 }
2107
2108 #ifdef PNG_READ_EXPAND_SUPPORTED
2109 if (png_ptr->transformations & PNG_EXPAND)
2110 {
2111 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
2112 {
2113 png_do_expand_palette(row_info, png_ptr->row_buf + 1,
2114 png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans);
2115 }
2116
2117 else
2118 {
2119 if (png_ptr->num_trans &&
2120 (png_ptr->transformations & PNG_EXPAND_tRNS))
2121 png_do_expand(row_info, png_ptr->row_buf + 1,
2122 &(png_ptr->trans_color));
2123
2124 else
2125 png_do_expand(row_info, png_ptr->row_buf + 1,
2126 NULL);
2127 }
2128 }
2129 #endif
2130
2131 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
2132 if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
2133 !(png_ptr->transformations & PNG_COMPOSE) &&
2134 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2135 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
2136 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
2137 0 /* at_start == false, because SWAP_ALPHA happens later */);
2138 #endif
2139
2140 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2141 if (png_ptr->transformations & PNG_RGB_TO_GRAY)
2142 {
2143 int rgb_error =
2144 png_do_rgb_to_gray(png_ptr, row_info,
2145 png_ptr->row_buf + 1);
2146
2147 if (rgb_error)
2148 {
2149 png_ptr->rgb_to_gray_status=1;
2150 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
2151 PNG_RGB_TO_GRAY_WARN)
2152 png_warning(png_ptr, "png_do_rgb_to_gray found nongray pixel");
2153
2154 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
2155 PNG_RGB_TO_GRAY_ERR)
2156 png_error(png_ptr, "png_do_rgb_to_gray found nongray pixel");
2157 }
2158 }
2159 #endif
2160
2161 /* From Andreas Dilger e-mail to png-implement, 26 March 1998:
2162 *
2163 * In most cases, the "simple transparency" should be done prior to doing
2164 * gray-to-RGB, or you will have to test 3x as many bytes to check if a
2165 * pixel is transparent. You would also need to make sure that the
2166 * transparency information is upgraded to RGB.
2167 *
2168 * To summarize, the current flow is:
2169 * - Gray + simple transparency -> compare 1 or 2 gray bytes and composite
2170 * with background "in place" if transparent,
2171 * convert to RGB if necessary
2172 * - Gray + alpha -> composite with gray background and remove alpha bytes,
2173 * convert to RGB if necessary
2174 *
2175 * To support RGB backgrounds for gray images we need:
2176 * - Gray + simple transparency -> convert to RGB + simple transparency,
2177 * compare 3 or 6 bytes and composite with
2178 * background "in place" if transparent
2179 * (3x compare/pixel compared to doing
2180 * composite with gray bkgrnd)
2181 * - Gray + alpha -> convert to RGB + alpha, composite with background and
2182 * remove alpha bytes (3x float
2183 * operations/pixel compared with composite
2184 * on gray background)
2185 *
2186 * Greg's change will do this. The reason it wasn't done before is for
2187 * performance, as this increases the per-pixel operations. If we would check
2188 * in advance if the background was gray or RGB, and position the gray-to-RGB
2189 * transform appropriately, then it would save a lot of work/time.
2190 */
2191
2192 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2193 /* If gray -> RGB, do so now only if background is non-gray; else do later
2194 * for performance reasons
2195 */
2196 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
2197 !(png_ptr->mode & PNG_BACKGROUND_IS_GRAY))
2198 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
2199 #endif
2200
2201 #if (defined PNG_READ_BACKGROUND_SUPPORTED) ||\
2202 (defined PNG_READ_ALPHA_MODE_SUPPORTED)
2203 if (png_ptr->transformations & PNG_COMPOSE)
2204 png_do_compose(row_info, png_ptr->row_buf + 1, png_ptr);
2205 #endif
2206
2207 #ifdef PNG_READ_GAMMA_SUPPORTED
2208 if ((png_ptr->transformations & PNG_GAMMA) &&
2209 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2210 /* Because RGB_TO_GRAY does the gamma transform. */
2211 !(png_ptr->transformations & PNG_RGB_TO_GRAY) &&
2212 #endif
2213 #if (defined PNG_READ_BACKGROUND_SUPPORTED) ||\
2214 (defined PNG_READ_ALPHA_MODE_SUPPORTED)
2215 /* Because PNG_COMPOSE does the gamma transform if there is something to
2216 * do (if there is an alpha channel or transparency.)
2217 */
2218 !((png_ptr->transformations & PNG_COMPOSE) &&
2219 ((png_ptr->num_trans != 0) ||
2220 (png_ptr->color_type & PNG_COLOR_MASK_ALPHA))) &&
2221 #endif
2222 /* Because png_init_read_transformations transforms the palette, unless
2223 * RGB_TO_GRAY will do the transform.
2224 */
2225 (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE))
2226 png_do_gamma(row_info, png_ptr->row_buf + 1, png_ptr);
2227 #endif
2228
2229 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
2230 if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
2231 (png_ptr->transformations & PNG_COMPOSE) &&
2232 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2233 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
2234 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
2235 0 /* at_start == false, because SWAP_ALPHA happens later */);
2236 #endif
2237
2238 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
2239 if ((png_ptr->transformations & PNG_ENCODE_ALPHA) &&
2240 (row_info->color_type & PNG_COLOR_MASK_ALPHA))
2241 png_do_encode_alpha(row_info, png_ptr->row_buf + 1, png_ptr);
2242 #endif
2243
2244 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2245 if (png_ptr->transformations & PNG_SCALE_16_TO_8)
2246 png_do_scale_16_to_8(row_info, png_ptr->row_buf + 1);
2247 #endif
2248
2249 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2250 /* There is no harm in doing both of these because only one has any effect,
2251 * by putting the 'scale' option first if the app asks for scale (either by
2252 * calling the API or in a TRANSFORM flag) this is what happens.
2253 */
2254 if (png_ptr->transformations & PNG_16_TO_8)
2255 png_do_chop(row_info, png_ptr->row_buf + 1);
2256 #endif
2257
2258 #ifdef PNG_READ_QUANTIZE_SUPPORTED
2259 if (png_ptr->transformations & PNG_QUANTIZE)
2260 {
2261 png_do_quantize(row_info, png_ptr->row_buf + 1,
2262 png_ptr->palette_lookup, png_ptr->quantize_index);
2263
2264 if (row_info->rowbytes == 0)
2265 png_error(png_ptr, "png_do_quantize returned rowbytes=0");
2266 }
2267 #endif /* PNG_READ_QUANTIZE_SUPPORTED */
2268
2269 #ifdef PNG_READ_EXPAND_16_SUPPORTED
2270 /* Do the expansion now, after all the arithmetic has been done. Notice
2271 * that previous transformations can handle the PNG_EXPAND_16 flag if this
2272 * is efficient (particularly true in the case of gamma correction, where
2273 * better accuracy results faster!)
2274 */
2275 if (png_ptr->transformations & PNG_EXPAND_16)
2276 png_do_expand_16(row_info, png_ptr->row_buf + 1);
2277 #endif
2278
2279 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2280 /* NOTE: moved here in 1.5.4 (from much later in this list.) */
2281 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
2282 (png_ptr->mode & PNG_BACKGROUND_IS_GRAY))
2283 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
2284 #endif
2285
2286 #ifdef PNG_READ_INVERT_SUPPORTED
2287 if (png_ptr->transformations & PNG_INVERT_MONO)
2288 png_do_invert(row_info, png_ptr->row_buf + 1);
2289 #endif
2290
2291 #ifdef PNG_READ_SHIFT_SUPPORTED
2292 if (png_ptr->transformations & PNG_SHIFT)
2293 png_do_unshift(row_info, png_ptr->row_buf + 1,
2294 &(png_ptr->shift));
2295 #endif
2296
2297 #ifdef PNG_READ_PACK_SUPPORTED
2298 if (png_ptr->transformations & PNG_PACK)
2299 png_do_unpack(row_info, png_ptr->row_buf + 1);
2300 #endif
2301
2302 #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
2303 /* Added at libpng-1.5.10 */
2304 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
2305 png_ptr->num_palette_max >= 0)
2306 png_do_check_palette_indexes(png_ptr, row_info);
2307 #endif
2308
2309 #ifdef PNG_READ_BGR_SUPPORTED
2310 if (png_ptr->transformations & PNG_BGR)
2311 png_do_bgr(row_info, png_ptr->row_buf + 1);
2312 #endif
2313
2314 #ifdef PNG_READ_PACKSWAP_SUPPORTED
2315 if (png_ptr->transformations & PNG_PACKSWAP)
2316 png_do_packswap(row_info, png_ptr->row_buf + 1);
2317 #endif
2318
2319 #ifdef PNG_READ_FILLER_SUPPORTED
2320 if (png_ptr->transformations & PNG_FILLER)
2321 png_do_read_filler(row_info, png_ptr->row_buf + 1,
2322 (png_uint_32)png_ptr->filler, png_ptr->flags);
2323 #endif
2324
2325 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
2326 if (png_ptr->transformations & PNG_INVERT_ALPHA)
2327 png_do_read_invert_alpha(row_info, png_ptr->row_buf + 1);
2328 #endif
2329
2330 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
2331 if (png_ptr->transformations & PNG_SWAP_ALPHA)
2332 png_do_read_swap_alpha(row_info, png_ptr->row_buf + 1);
2333 #endif
2334
2335 #ifdef PNG_READ_16BIT_SUPPORTED
2336 #ifdef PNG_READ_SWAP_SUPPORTED
2337 if (png_ptr->transformations & PNG_SWAP_BYTES)
2338 png_do_swap(row_info, png_ptr->row_buf + 1);
2339 #endif
2340 #endif
2341
2342 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
2343 if (png_ptr->transformations & PNG_USER_TRANSFORM)
2344 {
2345 if (png_ptr->read_user_transform_fn != NULL)
2346 (*(png_ptr->read_user_transform_fn)) /* User read transform function */
2347 (png_ptr, /* png_ptr */
2348 row_info, /* row_info: */
2349 /* png_uint_32 width; width of row */
2350 /* png_size_t rowbytes; number of bytes in row */
2351 /* png_byte color_type; color type of pixels */
2352 /* png_byte bit_depth; bit depth of samples */
2353 /* png_byte channels; number of channels (1-4) */
2354 /* png_byte pixel_depth; bits per pixel (depth*channels) */
2355 png_ptr->row_buf + 1); /* start of pixel data for row */
2356 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
2357 if (png_ptr->user_transform_depth)
2358 row_info->bit_depth = png_ptr->user_transform_depth;
2359
2360 if (png_ptr->user_transform_channels)
2361 row_info->channels = png_ptr->user_transform_channels;
2362 #endif
2363 row_info->pixel_depth = (png_byte)(row_info->bit_depth *
2364 row_info->channels);
2365
2366 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_info->width);
2367 }
2368 #endif
2369 }
2370
2371 #ifdef PNG_READ_PACK_SUPPORTED
2372 /* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
2373 * without changing the actual values. Thus, if you had a row with
2374 * a bit depth of 1, you would end up with bytes that only contained
2375 * the numbers 0 or 1. If you would rather they contain 0 and 255, use
2376 * png_do_shift() after this.
2377 */
2378 void /* PRIVATE */
2379 png_do_unpack(png_row_infop row_info, png_bytep row)
2380 {
2381 png_debug(1, "in png_do_unpack");
2382
2383 if (row_info->bit_depth < 8)
2384 {
2385 png_uint_32 i;
2386 png_uint_32 row_width=row_info->width;
2387
2388 switch (row_info->bit_depth)
2389 {
2390 case 1:
2391 {
2392 png_bytep sp = row + (png_size_t)((row_width - 1) >> 3);
2393 png_bytep dp = row + (png_size_t)row_width - 1;
2394 png_uint_32 shift = 7 - (int)((row_width + 7) & 0x07);
2395 for (i = 0; i < row_width; i++)
2396 {
2397 *dp = (png_byte)((*sp >> shift) & 0x01);
2398
2399 if (shift == 7)
2400 {
2401 shift = 0;
2402 sp--;
2403 }
2404
2405 else
2406 shift++;
2407
2408 dp--;
2409 }
2410 break;
2411 }
2412
2413 case 2:
2414 {
2415
2416 png_bytep sp = row + (png_size_t)((row_width - 1) >> 2);
2417 png_bytep dp = row + (png_size_t)row_width - 1;
2418 png_uint_32 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
2419 for (i = 0; i < row_width; i++)
2420 {
2421 *dp = (png_byte)((*sp >> shift) & 0x03);
2422
2423 if (shift == 6)
2424 {
2425 shift = 0;
2426 sp--;
2427 }
2428
2429 else
2430 shift += 2;
2431
2432 dp--;
2433 }
2434 break;
2435 }
2436
2437 case 4:
2438 {
2439 png_bytep sp = row + (png_size_t)((row_width - 1) >> 1);
2440 png_bytep dp = row + (png_size_t)row_width - 1;
2441 png_uint_32 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
2442 for (i = 0; i < row_width; i++)
2443 {
2444 *dp = (png_byte)((*sp >> shift) & 0x0f);
2445
2446 if (shift == 4)
2447 {
2448 shift = 0;
2449 sp--;
2450 }
2451
2452 else
2453 shift = 4;
2454
2455 dp--;
2456 }
2457 break;
2458 }
2459
2460 default:
2461 break;
2462 }
2463 row_info->bit_depth = 8;
2464 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2465 row_info->rowbytes = row_width * row_info->channels;
2466 }
2467 }
2468 #endif
2469
2470 #ifdef PNG_READ_SHIFT_SUPPORTED
2471 /* Reverse the effects of png_do_shift. This routine merely shifts the
2472 * pixels back to their significant bits values. Thus, if you have
2473 * a row of bit depth 8, but only 5 are significant, this will shift
2474 * the values back to 0 through 31.
2475 */
2476 void /* PRIVATE */
2477 png_do_unshift(png_row_infop row_info, png_bytep row,
2478 png_const_color_8p sig_bits)
2479 {
2480 int color_type;
2481
2482 png_debug(1, "in png_do_unshift");
2483
2484 /* The palette case has already been handled in the _init routine. */
2485 color_type = row_info->color_type;
2486
2487 if (color_type != PNG_COLOR_TYPE_PALETTE)
2488 {
2489 int shift[4];
2490 int channels = 0;
2491 int bit_depth = row_info->bit_depth;
2492
2493 if (color_type & PNG_COLOR_MASK_COLOR)
2494 {
2495 shift[channels++] = bit_depth - sig_bits->red;
2496 shift[channels++] = bit_depth - sig_bits->green;
2497 shift[channels++] = bit_depth - sig_bits->blue;
2498 }
2499
2500 else
2501 {
2502 shift[channels++] = bit_depth - sig_bits->gray;
2503 }
2504
2505 if (color_type & PNG_COLOR_MASK_ALPHA)
2506 {
2507 shift[channels++] = bit_depth - sig_bits->alpha;
2508 }
2509
2510 {
2511 int c, have_shift;
2512
2513 for (c = have_shift = 0; c < channels; ++c)
2514 {
2515 /* A shift of more than the bit depth is an error condition but it
2516 * gets ignored here.
2517 */
2518 if (shift[c] <= 0 || shift[c] >= bit_depth)
2519 shift[c] = 0;
2520
2521 else
2522 have_shift = 1;
2523 }
2524
2525 if (!have_shift)
2526 return;
2527 }
2528
2529 switch (bit_depth)
2530 {
2531 default:
2532 /* Must be 1bpp gray: should not be here! */
2533 /* NOTREACHED */
2534 break;
2535
2536 case 2:
2537 /* Must be 2bpp gray */
2538 /* assert(channels == 1 && shift[0] == 1) */
2539 {
2540 png_bytep bp = row;
2541 png_bytep bp_end = bp + row_info->rowbytes;
2542
2543 while (bp < bp_end)
2544 {
2545 int b = (*bp >> 1) & 0x55;
2546 *bp++ = (png_byte)b;
2547 }
2548 break;
2549 }
2550
2551 case 4:
2552 /* Must be 4bpp gray */
2553 /* assert(channels == 1) */
2554 {
2555 png_bytep bp = row;
2556 png_bytep bp_end = bp + row_info->rowbytes;
2557 int gray_shift = shift[0];
2558 int mask = 0xf >> gray_shift;
2559
2560 mask |= mask << 4;
2561
2562 while (bp < bp_end)
2563 {
2564 int b = (*bp >> gray_shift) & mask;
2565 *bp++ = (png_byte)b;
2566 }
2567 break;
2568 }
2569
2570 case 8:
2571 /* Single byte components, G, GA, RGB, RGBA */
2572 {
2573 png_bytep bp = row;
2574 png_bytep bp_end = bp + row_info->rowbytes;
2575 int channel = 0;
2576
2577 while (bp < bp_end)
2578 {
2579 int b = *bp >> shift[channel];
2580 if (++channel >= channels)
2581 channel = 0;
2582 *bp++ = (png_byte)b;
2583 }
2584 break;
2585 }
2586
2587 #ifdef PNG_READ_16BIT_SUPPORTED
2588 case 16:
2589 /* Double byte components, G, GA, RGB, RGBA */
2590 {
2591 png_bytep bp = row;
2592 png_bytep bp_end = bp + row_info->rowbytes;
2593 int channel = 0;
2594
2595 while (bp < bp_end)
2596 {
2597 int value = (bp[0] << 8) + bp[1];
2598
2599 value >>= shift[channel];
2600 if (++channel >= channels)
2601 channel = 0;
2602 *bp++ = (png_byte)(value >> 8);
2603 *bp++ = (png_byte)(value & 0xff);
2604 }
2605 break;
2606 }
2607 #endif
2608 }
2609 }
2610 }
2611 #endif
2612
2613 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2614 /* Scale rows of bit depth 16 down to 8 accurately */
2615 void /* PRIVATE */
2616 png_do_scale_16_to_8(png_row_infop row_info, png_bytep row)
2617 {
2618 png_debug(1, "in png_do_scale_16_to_8");
2619
2620 if (row_info->bit_depth == 16)
2621 {
2622 png_bytep sp = row; /* source */
2623 png_bytep dp = row; /* destination */
2624 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2625
2626 while (sp < ep)
2627 {
2628 /* The input is an array of 16 bit components, these must be scaled to
2629 * 8 bits each. For a 16 bit value V the required value (from the PNG
2630 * specification) is:
2631 *
2632 * (V * 255) / 65535
2633 *
2634 * This reduces to round(V / 257), or floor((V + 128.5)/257)
2635 *
2636 * Represent V as the two byte value vhi.vlo. Make a guess that the
2637 * result is the top byte of V, vhi, then the correction to this value
2638 * is:
2639 *
2640 * error = floor(((V-vhi.vhi) + 128.5) / 257)
2641 * = floor(((vlo-vhi) + 128.5) / 257)
2642 *
2643 * This can be approximated using integer arithmetic (and a signed
2644 * shift):
2645 *
2646 * error = (vlo-vhi+128) >> 8;
2647 *
2648 * The approximate differs from the exact answer only when (vlo-vhi) is
2649 * 128; it then gives a correction of +1 when the exact correction is
2650 * 0. This gives 128 errors. The exact answer (correct for all 16 bit
2651 * input values) is:
2652 *
2653 * error = (vlo-vhi+128)*65535 >> 24;
2654 *
2655 * An alternative arithmetic calculation which also gives no errors is:
2656 *
2657 * (V * 255 + 32895) >> 16
2658 */
2659
2660 png_int_32 tmp = *sp++; /* must be signed! */
2661 tmp += (((int)*sp++ - tmp + 128) * 65535) >> 24;
2662 *dp++ = (png_byte)tmp;
2663 }
2664
2665 row_info->bit_depth = 8;
2666 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2667 row_info->rowbytes = row_info->width * row_info->channels;
2668 }
2669 }
2670 #endif
2671
2672 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2673 void /* PRIVATE */
2674 /* Simply discard the low byte. This was the default behavior prior
2675 * to libpng-1.5.4.
2676 */
2677 png_do_chop(png_row_infop row_info, png_bytep row)
2678 {
2679 png_debug(1, "in png_do_chop");
2680
2681 if (row_info->bit_depth == 16)
2682 {
2683 png_bytep sp = row; /* source */
2684 png_bytep dp = row; /* destination */
2685 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2686
2687 while (sp < ep)
2688 {
2689 *dp++ = *sp;
2690 sp += 2; /* skip low byte */
2691 }
2692
2693 row_info->bit_depth = 8;
2694 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2695 row_info->rowbytes = row_info->width * row_info->channels;
2696 }
2697 }
2698 #endif
2699
2700 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
2701 void /* PRIVATE */
2702 png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
2703 {
2704 png_debug(1, "in png_do_read_swap_alpha");
2705
2706 {
2707 png_uint_32 row_width = row_info->width;
2708 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2709 {
2710 /* This converts from RGBA to ARGB */
2711 if (row_info->bit_depth == 8)
2712 {
2713 png_bytep sp = row + row_info->rowbytes;
2714 png_bytep dp = sp;
2715 png_byte save;
2716 png_uint_32 i;
2717
2718 for (i = 0; i < row_width; i++)
2719 {
2720 save = *(--sp);
2721 *(--dp) = *(--sp);
2722 *(--dp) = *(--sp);
2723 *(--dp) = *(--sp);
2724 *(--dp) = save;
2725 }
2726 }
2727
2728 #ifdef PNG_READ_16BIT_SUPPORTED
2729 /* This converts from RRGGBBAA to AARRGGBB */
2730 else
2731 {
2732 png_bytep sp = row + row_info->rowbytes;
2733 png_bytep dp = sp;
2734 png_byte save[2];
2735 png_uint_32 i;
2736
2737 for (i = 0; i < row_width; i++)
2738 {
2739 save[0] = *(--sp);
2740 save[1] = *(--sp);
2741 *(--dp) = *(--sp);
2742 *(--dp) = *(--sp);
2743 *(--dp) = *(--sp);
2744 *(--dp) = *(--sp);
2745 *(--dp) = *(--sp);
2746 *(--dp) = *(--sp);
2747 *(--dp) = save[0];
2748 *(--dp) = save[1];
2749 }
2750 }
2751 #endif
2752 }
2753
2754 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2755 {
2756 /* This converts from GA to AG */
2757 if (row_info->bit_depth == 8)
2758 {
2759 png_bytep sp = row + row_info->rowbytes;
2760 png_bytep dp = sp;
2761 png_byte save;
2762 png_uint_32 i;
2763
2764 for (i = 0; i < row_width; i++)
2765 {
2766 save = *(--sp);
2767 *(--dp) = *(--sp);
2768 *(--dp) = save;
2769 }
2770 }
2771
2772 #ifdef PNG_READ_16BIT_SUPPORTED
2773 /* This converts from GGAA to AAGG */
2774 else
2775 {
2776 png_bytep sp = row + row_info->rowbytes;
2777 png_bytep dp = sp;
2778 png_byte save[2];
2779 png_uint_32 i;
2780
2781 for (i = 0; i < row_width; i++)
2782 {
2783 save[0] = *(--sp);
2784 save[1] = *(--sp);
2785 *(--dp) = *(--sp);
2786 *(--dp) = *(--sp);
2787 *(--dp) = save[0];
2788 *(--dp) = save[1];
2789 }
2790 }
2791 #endif
2792 }
2793 }
2794 }
2795 #endif
2796
2797 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
2798 void /* PRIVATE */
2799 png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
2800 {
2801 png_uint_32 row_width;
2802 png_debug(1, "in png_do_read_invert_alpha");
2803
2804 row_width = row_info->width;
2805 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2806 {
2807 if (row_info->bit_depth == 8)
2808 {
2809 /* This inverts the alpha channel in RGBA */
2810 png_bytep sp = row + row_info->rowbytes;
2811 png_bytep dp = sp;
2812 png_uint_32 i;
2813
2814 for (i = 0; i < row_width; i++)
2815 {
2816 *(--dp) = (png_byte)(255 - *(--sp));
2817
2818 /* This does nothing:
2819 *(--dp) = *(--sp);
2820 *(--dp) = *(--sp);
2821 *(--dp) = *(--sp);
2822 We can replace it with:
2823 */
2824 sp-=3;
2825 dp=sp;
2826 }
2827 }
2828
2829 #ifdef PNG_READ_16BIT_SUPPORTED
2830 /* This inverts the alpha channel in RRGGBBAA */
2831 else
2832 {
2833 png_bytep sp = row + row_info->rowbytes;
2834 png_bytep dp = sp;
2835 png_uint_32 i;
2836
2837 for (i = 0; i < row_width; i++)
2838 {
2839 *(--dp) = (png_byte)(255 - *(--sp));
2840 *(--dp) = (png_byte)(255 - *(--sp));
2841
2842 /* This does nothing:
2843 *(--dp) = *(--sp);
2844 *(--dp) = *(--sp);
2845 *(--dp) = *(--sp);
2846 *(--dp) = *(--sp);
2847 *(--dp) = *(--sp);
2848 *(--dp) = *(--sp);
2849 We can replace it with:
2850 */
2851 sp-=6;
2852 dp=sp;
2853 }
2854 }
2855 #endif
2856 }
2857 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2858 {
2859 if (row_info->bit_depth == 8)
2860 {
2861 /* This inverts the alpha channel in GA */
2862 png_bytep sp = row + row_info->rowbytes;
2863 png_bytep dp = sp;
2864 png_uint_32 i;
2865
2866 for (i = 0; i < row_width; i++)
2867 {
2868 *(--dp) = (png_byte)(255 - *(--sp));
2869 *(--dp) = *(--sp);
2870 }
2871 }
2872
2873 #ifdef PNG_READ_16BIT_SUPPORTED
2874 else
2875 {
2876 /* This inverts the alpha channel in GGAA */
2877 png_bytep sp = row + row_info->rowbytes;
2878 png_bytep dp = sp;
2879 png_uint_32 i;
2880
2881 for (i = 0; i < row_width; i++)
2882 {
2883 *(--dp) = (png_byte)(255 - *(--sp));
2884 *(--dp) = (png_byte)(255 - *(--sp));
2885 /*
2886 *(--dp) = *(--sp);
2887 *(--dp) = *(--sp);
2888 */
2889 sp-=2;
2890 dp=sp;
2891 }
2892 }
2893 #endif
2894 }
2895 }
2896 #endif
2897
2898 #ifdef PNG_READ_FILLER_SUPPORTED
2899 /* Add filler channel if we have RGB color */
2900 void /* PRIVATE */
2901 png_do_read_filler(png_row_infop row_info, png_bytep row,
2902 png_uint_32 filler, png_uint_32 flags)
2903 {
2904 png_uint_32 i;
2905 png_uint_32 row_width = row_info->width;
2906
2907 #ifdef PNG_READ_16BIT_SUPPORTED
2908 png_byte hi_filler = (png_byte)((filler>>8) & 0xff);
2909 #endif
2910 png_byte lo_filler = (png_byte)(filler & 0xff);
2911
2912 png_debug(1, "in png_do_read_filler");
2913
2914 if (
2915 row_info->color_type == PNG_COLOR_TYPE_GRAY)
2916 {
2917 if (row_info->bit_depth == 8)
2918 {
2919 if (flags & PNG_FLAG_FILLER_AFTER)
2920 {
2921 /* This changes the data from G to GX */
2922 png_bytep sp = row + (png_size_t)row_width;
2923 png_bytep dp = sp + (png_size_t)row_width;
2924 for (i = 1; i < row_width; i++)
2925 {
2926 *(--dp) = lo_filler;
2927 *(--dp) = *(--sp);
2928 }
2929 *(--dp) = lo_filler;
2930 row_info->channels = 2;
2931 row_info->pixel_depth = 16;
2932 row_info->rowbytes = row_width * 2;
2933 }
2934
2935 else
2936 {
2937 /* This changes the data from G to XG */
2938 png_bytep sp = row + (png_size_t)row_width;
2939 png_bytep dp = sp + (png_size_t)row_width;
2940 for (i = 0; i < row_width; i++)
2941 {
2942 *(--dp) = *(--sp);
2943 *(--dp) = lo_filler;
2944 }
2945 row_info->channels = 2;
2946 row_info->pixel_depth = 16;
2947 row_info->rowbytes = row_width * 2;
2948 }
2949 }
2950
2951 #ifdef PNG_READ_16BIT_SUPPORTED
2952 else if (row_info->bit_depth == 16)
2953 {
2954 if (flags & PNG_FLAG_FILLER_AFTER)
2955 {
2956 /* This changes the data from GG to GGXX */
2957 png_bytep sp = row + (png_size_t)row_width * 2;
2958 png_bytep dp = sp + (png_size_t)row_width * 2;
2959 for (i = 1; i < row_width; i++)
2960 {
2961 *(--dp) = hi_filler;
2962 *(--dp) = lo_filler;
2963 *(--dp) = *(--sp);
2964 *(--dp) = *(--sp);
2965 }
2966 *(--dp) = hi_filler;
2967 *(--dp) = lo_filler;
2968 row_info->channels = 2;
2969 row_info->pixel_depth = 32;
2970 row_info->rowbytes = row_width * 4;
2971 }
2972
2973 else
2974 {
2975 /* This changes the data from GG to XXGG */
2976 png_bytep sp = row + (png_size_t)row_width * 2;
2977 png_bytep dp = sp + (png_size_t)row_width * 2;
2978 for (i = 0; i < row_width; i++)
2979 {
2980 *(--dp) = *(--sp);
2981 *(--dp) = *(--sp);
2982 *(--dp) = hi_filler;
2983 *(--dp) = lo_filler;
2984 }
2985 row_info->channels = 2;
2986 row_info->pixel_depth = 32;
2987 row_info->rowbytes = row_width * 4;
2988 }
2989 }
2990 #endif
2991 } /* COLOR_TYPE == GRAY */
2992 else if (row_info->color_type == PNG_COLOR_TYPE_RGB)
2993 {
2994 if (row_info->bit_depth == 8)
2995 {
2996 if (flags & PNG_FLAG_FILLER_AFTER)
2997 {
2998 /* This changes the data from RGB to RGBX */
2999 png_bytep sp = row + (png_size_t)row_width * 3;
3000 png_bytep dp = sp + (png_size_t)row_width;
3001 for (i = 1; i < row_width; i++)
3002 {
3003 *(--dp) = lo_filler;
3004 *(--dp) = *(--sp);
3005 *(--dp) = *(--sp);
3006 *(--dp) = *(--sp);
3007 }
3008 *(--dp) = lo_filler;
3009 row_info->channels = 4;
3010 row_info->pixel_depth = 32;
3011 row_info->rowbytes = row_width * 4;
3012 }
3013
3014 else
3015 {
3016 /* This changes the data from RGB to XRGB */
3017 png_bytep sp = row + (png_size_t)row_width * 3;
3018 png_bytep dp = sp + (png_size_t)row_width;
3019 for (i = 0; i < row_width; i++)
3020 {
3021 *(--dp) = *(--sp);
3022 *(--dp) = *(--sp);
3023 *(--dp) = *(--sp);
3024 *(--dp) = lo_filler;
3025 }
3026 row_info->channels = 4;
3027 row_info->pixel_depth = 32;
3028 row_info->rowbytes = row_width * 4;
3029 }
3030 }
3031
3032 #ifdef PNG_READ_16BIT_SUPPORTED
3033 else if (row_info->bit_depth == 16)
3034 {
3035 if (flags & PNG_FLAG_FILLER_AFTER)
3036 {
3037 /* This changes the data from RRGGBB to RRGGBBXX */
3038 png_bytep sp = row + (png_size_t)row_width * 6;
3039 png_bytep dp = sp + (png_size_t)row_width * 2;
3040 for (i = 1; i < row_width; i++)
3041 {
3042 *(--dp) = hi_filler;
3043 *(--dp) = lo_filler;
3044 *(--dp) = *(--sp);
3045 *(--dp) = *(--sp);
3046 *(--dp) = *(--sp);
3047 *(--dp) = *(--sp);
3048 *(--dp) = *(--sp);
3049 *(--dp) = *(--sp);
3050 }
3051 *(--dp) = hi_filler;
3052 *(--dp) = lo_filler;
3053 row_info->channels = 4;
3054 row_info->pixel_depth = 64;
3055 row_info->rowbytes = row_width * 8;
3056 }
3057
3058 else
3059 {
3060 /* This changes the data from RRGGBB to XXRRGGBB */
3061 png_bytep sp = row + (png_size_t)row_width * 6;
3062 png_bytep dp = sp + (png_size_t)row_width * 2;
3063 for (i = 0; i < row_width; i++)
3064 {
3065 *(--dp) = *(--sp);
3066 *(--dp) = *(--sp);
3067 *(--dp) = *(--sp);
3068 *(--dp) = *(--sp);
3069 *(--dp) = *(--sp);
3070 *(--dp) = *(--sp);
3071 *(--dp) = hi_filler;
3072 *(--dp) = lo_filler;
3073 }
3074
3075 row_info->channels = 4;
3076 row_info->pixel_depth = 64;
3077 row_info->rowbytes = row_width * 8;
3078 }
3079 }
3080 #endif
3081 } /* COLOR_TYPE == RGB */
3082 }
3083 #endif
3084
3085 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
3086 /* Expand grayscale files to RGB, with or without alpha */
3087 void /* PRIVATE */
3088 png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
3089 {
3090 png_uint_32 i;
3091 png_uint_32 row_width = row_info->width;
3092
3093 png_debug(1, "in png_do_gray_to_rgb");
3094
3095 if (row_info->bit_depth >= 8 &&
3096 !(row_info->color_type & PNG_COLOR_MASK_COLOR))
3097 {
3098 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
3099 {
3100 if (row_info->bit_depth == 8)
3101 {
3102 /* This changes G to RGB */
3103 png_bytep sp = row + (png_size_t)row_width - 1;
3104 png_bytep dp = sp + (png_size_t)row_width * 2;
3105 for (i = 0; i < row_width; i++)
3106 {
3107 *(dp--) = *sp;
3108 *(dp--) = *sp;
3109 *(dp--) = *(sp--);
3110 }
3111 }
3112
3113 else
3114 {
3115 /* This changes GG to RRGGBB */
3116 png_bytep sp = row + (png_size_t)row_width * 2 - 1;
3117 png_bytep dp = sp + (png_size_t)row_width * 4;
3118 for (i = 0; i < row_width; i++)
3119 {
3120 *(dp--) = *sp;
3121 *(dp--) = *(sp - 1);
3122 *(dp--) = *sp;
3123 *(dp--) = *(sp - 1);
3124 *(dp--) = *(sp--);
3125 *(dp--) = *(sp--);
3126 }
3127 }
3128 }
3129
3130 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
3131 {
3132 if (row_info->bit_depth == 8)
3133 {
3134 /* This changes GA to RGBA */
3135 png_bytep sp = row + (png_size_t)row_width * 2 - 1;
3136 png_bytep dp = sp + (png_size_t)row_width * 2;
3137 for (i = 0; i < row_width; i++)
3138 {
3139 *(dp--) = *(sp--);
3140 *(dp--) = *sp;
3141 *(dp--) = *sp;
3142 *(dp--) = *(sp--);
3143 }
3144 }
3145
3146 else
3147 {
3148 /* This changes GGAA to RRGGBBAA */
3149 png_bytep sp = row + (png_size_t)row_width * 4 - 1;
3150 png_bytep dp = sp + (png_size_t)row_width * 4;
3151 for (i = 0; i < row_width; i++)
3152 {
3153 *(dp--) = *(sp--);
3154 *(dp--) = *(sp--);
3155 *(dp--) = *sp;
3156 *(dp--) = *(sp - 1);
3157 *(dp--) = *sp;
3158 *(dp--) = *(sp - 1);
3159 *(dp--) = *(sp--);
3160 *(dp--) = *(sp--);
3161 }
3162 }
3163 }
3164 row_info->channels = (png_byte)(row_info->channels + 2);
3165 row_info->color_type |= PNG_COLOR_MASK_COLOR;
3166 row_info->pixel_depth = (png_byte)(row_info->channels *
3167 row_info->bit_depth);
3168 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
3169 }
3170 }
3171 #endif
3172
3173 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
3174 /* Reduce RGB files to grayscale, with or without alpha
3175 * using the equation given in Poynton's ColorFAQ of 1998-01-04 at
3176 * <http://www.inforamp.net/~poynton/> (THIS LINK IS DEAD June 2008 but
3177 * versions dated 1998 through November 2002 have been archived at
3178 * http://web.archive.org/web/20000816232553/http://www.inforamp.net/
3179 * ~poynton/notes/colour_and_gamma/ColorFAQ.txt )
3180 * Charles Poynton poynton at poynton.com
3181 *
3182 * Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
3183 *
3184 * which can be expressed with integers as
3185 *
3186 * Y = (6969 * R + 23434 * G + 2365 * B)/32768
3187 *
3188 * Poynton's current link (as of January 2003 through July 2011):
3189 * <http://www.poynton.com/notes/colour_and_gamma/>
3190 * has changed the numbers slightly:
3191 *
3192 * Y = 0.2126*R + 0.7152*G + 0.0722*B
3193 *
3194 * which can be expressed with integers as
3195 *
3196 * Y = (6966 * R + 23436 * G + 2366 * B)/32768
3197 *
3198 * Historically, however, libpng uses numbers derived from the ITU-R Rec 709
3199 * end point chromaticities and the D65 white point. Depending on the
3200 * precision used for the D65 white point this produces a variety of different
3201 * numbers, however if the four decimal place value used in ITU-R Rec 709 is
3202 * used (0.3127,0.3290) the Y calculation would be:
3203 *
3204 * Y = (6968 * R + 23435 * G + 2366 * B)/32768
3205 *
3206 * While this is correct the rounding results in an overflow for white, because
3207 * the sum of the rounded coefficients is 32769, not 32768. Consequently
3208 * libpng uses, instead, the closest non-overflowing approximation:
3209 *
3210 * Y = (6968 * R + 23434 * G + 2366 * B)/32768
3211 *
3212 * Starting with libpng-1.5.5, if the image being converted has a cHRM chunk
3213 * (including an sRGB chunk) then the chromaticities are used to calculate the
3214 * coefficients. See the chunk handling in pngrutil.c for more information.
3215 *
3216 * In all cases the calculation is to be done in a linear colorspace. If no
3217 * gamma information is available to correct the encoding of the original RGB
3218 * values this results in an implicit assumption that the original PNG RGB
3219 * values were linear.
3220 *
3221 * Other integer coefficents can be used via png_set_rgb_to_gray(). Because
3222 * the API takes just red and green coefficients the blue coefficient is
3223 * calculated to make the sum 32768. This will result in different rounding
3224 * to that used above.
3225 */
3226 int /* PRIVATE */
3227 png_do_rgb_to_gray(png_structp png_ptr, png_row_infop row_info, png_bytep row)
3228
3229 {
3230 int rgb_error = 0;
3231
3232 png_debug(1, "in png_do_rgb_to_gray");
3233
3234 if (!(row_info->color_type & PNG_COLOR_MASK_PALETTE) &&
3235 (row_info->color_type & PNG_COLOR_MASK_COLOR))
3236 {
3237 PNG_CONST png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff;
3238 PNG_CONST png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff;
3239 PNG_CONST png_uint_32 bc = 32768 - rc - gc;
3240 PNG_CONST png_uint_32 row_width = row_info->width;
3241 PNG_CONST int have_alpha =
3242 (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0;
3243
3244 if (row_info->bit_depth == 8)
3245 {
3246 #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
3247 /* Notice that gamma to/from 1 are not necessarily inverses (if
3248 * there is an overall gamma correction). Prior to 1.5.5 this code
3249 * checked the linearized values for equality; this doesn't match
3250 * the documentation, the original values must be checked.
3251 */
3252 if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL)
3253 {
3254 png_bytep sp = row;
3255 png_bytep dp = row;
3256 png_uint_32 i;
3257
3258 for (i = 0; i < row_width; i++)
3259 {
3260 png_byte red = *(sp++);
3261 png_byte green = *(sp++);
3262 png_byte blue = *(sp++);
3263
3264 if (red != green || red != blue)
3265 {
3266 red = png_ptr->gamma_to_1[red];
3267 green = png_ptr->gamma_to_1[green];
3268 blue = png_ptr->gamma_to_1[blue];
3269
3270 rgb_error |= 1;
3271 *(dp++) = png_ptr->gamma_from_1[
3272 (rc*red + gc*green + bc*blue + 16384)>>15];
3273 }
3274
3275 else
3276 {
3277 /* If there is no overall correction the table will not be
3278 * set.
3279 */
3280 if (png_ptr->gamma_table != NULL)
3281 red = png_ptr->gamma_table[red];
3282
3283 *(dp++) = red;
3284 }
3285
3286 if (have_alpha)
3287 *(dp++) = *(sp++);
3288 }
3289 }
3290 else
3291 #endif
3292 {
3293 png_bytep sp = row;
3294 png_bytep dp = row;
3295 png_uint_32 i;
3296
3297 for (i = 0; i < row_width; i++)
3298 {
3299 png_byte red = *(sp++);
3300 png_byte green = *(sp++);
3301 png_byte blue = *(sp++);
3302
3303 if (red != green || red != blue)
3304 {
3305 rgb_error |= 1;
3306 /* NOTE: this is the historical approach which simply
3307 * truncates the results.
3308 */
3309 *(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15);
3310 }
3311
3312 else
3313 *(dp++) = red;
3314
3315 if (have_alpha)
3316 *(dp++) = *(sp++);
3317 }
3318 }
3319 }
3320
3321 else /* RGB bit_depth == 16 */
3322 {
3323 #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
3324 if (png_ptr->gamma_16_to_1 != NULL && png_ptr->gamma_16_from_1 != NULL)
3325 {
3326 png_bytep sp = row;
3327 png_bytep dp = row;
3328 png_uint_32 i;
3329
3330 for (i = 0; i < row_width; i++)
3331 {
3332 png_uint_16 red, green, blue, w;
3333
3334 red = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
3335 green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
3336 blue = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
3337
3338 if (red == green && red == blue)
3339 {
3340 if (png_ptr->gamma_16_table != NULL)
3341 w = png_ptr->gamma_16_table[(red&0xff)
3342 >> png_ptr->gamma_shift][red>>8];
3343
3344 else
3345 w = red;
3346 }
3347
3348 else
3349 {
3350 png_uint_16 red_1 = png_ptr->gamma_16_to_1[(red&0xff)
3351 >> png_ptr->gamma_shift][red>>8];
3352 png_uint_16 green_1 =
3353 png_ptr->gamma_16_to_1[(green&0xff) >>
3354 png_ptr->gamma_shift][green>>8];
3355 png_uint_16 blue_1 = png_ptr->gamma_16_to_1[(blue&0xff)
3356 >> png_ptr->gamma_shift][blue>>8];
3357 png_uint_16 gray16 = (png_uint_16)((rc*red_1 + gc*green_1
3358 + bc*blue_1 + 16384)>>15);
3359 w = png_ptr->gamma_16_from_1[(gray16&0xff) >>
3360 png_ptr->gamma_shift][gray16 >> 8];
3361 rgb_error |= 1;
3362 }
3363
3364 *(dp++) = (png_byte)((w>>8) & 0xff);
3365 *(dp++) = (png_byte)(w & 0xff);
3366
3367 if (have_alpha)
3368 {
3369 *(dp++) = *(sp++);
3370 *(dp++) = *(sp++);
3371 }
3372 }
3373 }
3374 else
3375 #endif
3376 {
3377 png_bytep sp = row;
3378 png_bytep dp = row;
3379 png_uint_32 i;
3380
3381 for (i = 0; i < row_width; i++)
3382 {
3383 png_uint_16 red, green, blue, gray16;
3384
3385 red = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
3386 green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
3387 blue = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
3388
3389 if (red != green || red != blue)
3390 rgb_error |= 1;
3391
3392 /* From 1.5.5 in the 16 bit case do the accurate conversion even
3393 * in the 'fast' case - this is because this is where the code
3394 * ends up when handling linear 16 bit data.
3395 */
3396 gray16 = (png_uint_16)((rc*red + gc*green + bc*blue + 16384) >>
3397 15);
3398 *(dp++) = (png_byte)((gray16>>8) & 0xff);
3399 *(dp++) = (png_byte)(gray16 & 0xff);
3400
3401 if (have_alpha)
3402 {
3403 *(dp++) = *(sp++);
3404 *(dp++) = *(sp++);
3405 }
3406 }
3407 }
3408 }
3409
3410 row_info->channels = (png_byte)(row_info->channels - 2);
3411 row_info->color_type = (png_byte)(row_info->color_type &
3412 ~PNG_COLOR_MASK_COLOR);
3413 row_info->pixel_depth = (png_byte)(row_info->channels *
3414 row_info->bit_depth);
3415 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
3416 }
3417 return rgb_error;
3418 }
3419 #endif
3420 #endif /* PNG_READ_TRANSFORMS_SUPPORTED */
3421
3422 #ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
3423 /* Build a grayscale palette. Palette is assumed to be 1 << bit_depth
3424 * large of png_color. This lets grayscale images be treated as
3425 * paletted. Most useful for gamma correction and simplification
3426 * of code. This API is not used internally.
3427 */
3428 void PNGAPI
3429 png_build_grayscale_palette(int bit_depth, png_colorp palette)
3430 {
3431 int num_palette;
3432 int color_inc;
3433 int i;
3434 int v;
3435
3436 png_debug(1, "in png_do_build_grayscale_palette");
3437
3438 if (palette == NULL)
3439 return;
3440
3441 switch (bit_depth)
3442 {
3443 case 1:
3444 num_palette = 2;
3445 color_inc = 0xff;
3446 break;
3447
3448 case 2:
3449 num_palette = 4;
3450 color_inc = 0x55;
3451 break;
3452
3453 case 4:
3454 num_palette = 16;
3455 color_inc = 0x11;
3456 break;
3457
3458 case 8:
3459 num_palette = 256;
3460 color_inc = 1;
3461 break;
3462
3463 default:
3464 num_palette = 0;
3465 color_inc = 0;
3466 break;
3467 }
3468
3469 for (i = 0, v = 0; i < num_palette; i++, v += color_inc)
3470 {
3471 palette[i].red = (png_byte)v;
3472 palette[i].green = (png_byte)v;
3473 palette[i].blue = (png_byte)v;
3474 }
3475 }
3476 #endif
3477
3478
3479 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
3480 #if (defined PNG_READ_BACKGROUND_SUPPORTED) ||\
3481 (defined PNG_READ_ALPHA_MODE_SUPPORTED)
3482 /* Replace any alpha or transparency with the supplied background color.
3483 * "background" is already in the screen gamma, while "background_1" is
3484 * at a gamma of 1.0. Paletted files have already been taken care of.
3485 */
3486 void /* PRIVATE */
3487 png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
3488 {
3489 #ifdef PNG_READ_GAMMA_SUPPORTED
3490 png_const_bytep gamma_table = png_ptr->gamma_table;
3491 png_const_bytep gamma_from_1 = png_ptr->gamma_from_1;
3492 png_const_bytep gamma_to_1 = png_ptr->gamma_to_1;
3493 png_const_uint_16pp gamma_16 = png_ptr->gamma_16_table;
3494 png_const_uint_16pp gamma_16_from_1 = png_ptr->gamma_16_from_1;
3495 png_const_uint_16pp gamma_16_to_1 = png_ptr->gamma_16_to_1;
3496 int gamma_shift = png_ptr->gamma_shift;
3497 #endif
3498
3499 png_bytep sp;
3500 png_uint_32 i;
3501 png_uint_32 row_width = row_info->width;
3502 int optimize = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0;
3503 int shift;
3504
3505 png_debug(1, "in png_do_compose");
3506
3507 {
3508 switch (row_info->color_type)
3509 {
3510 case PNG_COLOR_TYPE_GRAY:
3511 {
3512 switch (row_info->bit_depth)
3513 {
3514 case 1:
3515 {
3516 sp = row;
3517 shift = 7;
3518 for (i = 0; i < row_width; i++)
3519 {
3520 if ((png_uint_16)((*sp >> shift) & 0x01)
3521 == png_ptr->trans_color.gray)
3522 {
3523 *sp &= (png_byte)((0x7f7f >> (7 - shift)) & 0xff);
3524 *sp |= (png_byte)(png_ptr->background.gray << shift);
3525 }
3526
3527 if (!shift)
3528 {
3529 shift = 7;
3530 sp++;
3531 }
3532
3533 else
3534 shift--;
3535 }
3536 break;
3537 }
3538
3539 case 2:
3540 {
3541 #ifdef PNG_READ_GAMMA_SUPPORTED
3542 if (gamma_table != NULL)
3543 {
3544 sp = row;
3545 shift = 6;
3546 for (i = 0; i < row_width; i++)
3547 {
3548 if ((png_uint_16)((*sp >> shift) & 0x03)
3549 == png_ptr->trans_color.gray)
3550 {
3551 *sp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);
3552 *sp |= (png_byte)(png_ptr->background.gray << shift);
3553 }
3554
3555 else
3556 {
3557 png_byte p = (png_byte)((*sp >> shift) & 0x03);
3558 png_byte g = (png_byte)((gamma_table [p | (p << 2) |
3559 (p << 4) | (p << 6)] >> 6) & 0x03);
3560 *sp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);
3561 *sp |= (png_byte)(g << shift);
3562 }
3563
3564 if (!shift)
3565 {
3566 shift = 6;
3567 sp++;
3568 }
3569
3570 else
3571 shift -= 2;
3572 }
3573 }
3574
3575 else
3576 #endif
3577 {
3578 sp = row;
3579 shift = 6;
3580 for (i = 0; i < row_width; i++)
3581 {
3582 if ((png_uint_16)((*sp >> shift) & 0x03)
3583 == png_ptr->trans_color.gray)
3584 {
3585 *sp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);
3586 *sp |= (png_byte)(png_ptr->background.gray << shift);
3587 }
3588
3589 if (!shift)
3590 {
3591 shift = 6;
3592 sp++;
3593 }
3594
3595 else
3596 shift -= 2;
3597 }
3598 }
3599 break;
3600 }
3601
3602 case 4:
3603 {
3604 #ifdef PNG_READ_GAMMA_SUPPORTED
3605 if (gamma_table != NULL)
3606 {
3607 sp = row;
3608 shift = 4;
3609 for (i = 0; i < row_width; i++)
3610 {
3611 if ((png_uint_16)((*sp >> shift) & 0x0f)
3612 == png_ptr->trans_color.gray)
3613 {
3614 *sp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);
3615 *sp |= (png_byte)(png_ptr->background.gray << shift);
3616 }
3617
3618 else
3619 {
3620 png_byte p = (png_byte)((*sp >> shift) & 0x0f);
3621 png_byte g = (png_byte)((gamma_table[p |
3622 (p << 4)] >> 4) & 0x0f);
3623 *sp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);
3624 *sp |= (png_byte)(g << shift);
3625 }
3626
3627 if (!shift)
3628 {
3629 shift = 4;
3630 sp++;
3631 }
3632
3633 else
3634 shift -= 4;
3635 }
3636 }
3637
3638 else
3639 #endif
3640 {
3641 sp = row;
3642 shift = 4;
3643 for (i = 0; i < row_width; i++)
3644 {
3645 if ((png_uint_16)((*sp >> shift) & 0x0f)
3646 == png_ptr->trans_color.gray)
3647 {
3648 *sp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);
3649 *sp |= (png_byte)(png_ptr->background.gray << shift);
3650 }
3651
3652 if (!shift)
3653 {
3654 shift = 4;
3655 sp++;
3656 }
3657
3658 else
3659 shift -= 4;
3660 }
3661 }
3662 break;
3663 }
3664
3665 case 8:
3666 {
3667 #ifdef PNG_READ_GAMMA_SUPPORTED
3668 if (gamma_table != NULL)
3669 {
3670 sp = row;
3671 for (i = 0; i < row_width; i++, sp++)
3672 {
3673 if (*sp == png_ptr->trans_color.gray)
3674 *sp = (png_byte)png_ptr->background.gray;
3675
3676 else
3677 *sp = gamma_table[*sp];
3678 }
3679 }
3680 else
3681 #endif
3682 {
3683 sp = row;
3684 for (i = 0; i < row_width; i++, sp++)
3685 {
3686 if (*sp == png_ptr->trans_color.gray)
3687 *sp = (png_byte)png_ptr->background.gray;
3688 }
3689 }
3690 break;
3691 }
3692
3693 case 16:
3694 {
3695 #ifdef PNG_READ_GAMMA_SUPPORTED
3696 if (gamma_16 != NULL)
3697 {
3698 sp = row;
3699 for (i = 0; i < row_width; i++, sp += 2)
3700 {
3701 png_uint_16 v;
3702
3703 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3704
3705 if (v == png_ptr->trans_color.gray)
3706 {
3707 /* Background is already in screen gamma */
3708 *sp = (png_byte)((png_ptr->background.gray >> 8)
3709 & 0xff);
3710 *(sp + 1) = (png_byte)(png_ptr->background.gray
3711 & 0xff);
3712 }
3713
3714 else
3715 {
3716 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3717 *sp = (png_byte)((v >> 8) &am