1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation. Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 */
24
25 /* pngrtran.c - transforms the data in a row for PNG readers
26 *
27 * This file is available under and governed by the GNU General Public
28 * License version 2 only, as published by the Free Software Foundation.
29 * However, the following notice accompanied the original version of this
30 * file and, per its terms, should not be removed:
31 *
32 * Last changed in libpng 1.6.15 [November 20, 2014]
33 * Copyright (c) 1998-2014 Glenn Randers-Pehrson
34 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
35 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
36 *
37 * This code is released under the libpng license.
38 * For conditions of distribution and use, see the disclaimer
39 * and license in png.h
40 *
41 * This file contains functions optionally called by an application
42 * in order to tell libpng how to handle data when reading a PNG.
43 * Transformations that are used in both reading and writing are
44 * in pngtrans.c.
45 */
46
47 #include "pngpriv.h"
48
49 #ifdef PNG_READ_SUPPORTED
50
51 /* Set the action on getting a CRC error for an ancillary or critical chunk. */
52 void PNGAPI
53 png_set_crc_action(png_structrp png_ptr, int crit_action, int ancil_action)
54 {
55 png_debug(1, "in png_set_crc_action");
56
57 if (png_ptr == NULL)
58 return;
59
60 /* Tell libpng how we react to CRC errors in critical chunks */
61 switch (crit_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_CRITICAL_MASK;
68 png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE;
69 break;
70
71 case PNG_CRC_QUIET_USE: /* Quiet/use data */
72 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
73 png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE |
74 PNG_FLAG_CRC_CRITICAL_IGNORE;
75 break;
76
77 case PNG_CRC_WARN_DISCARD: /* Not a valid action for critical data */
78 png_warning(png_ptr,
79 "Can't discard critical data on CRC error");
80 case PNG_CRC_ERROR_QUIT: /* Error/quit */
81
82 case PNG_CRC_DEFAULT:
83 default:
84 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
85 break;
86 }
87
88 /* Tell libpng how we react to CRC errors in ancillary chunks */
89 switch (ancil_action)
90 {
91 case PNG_CRC_NO_CHANGE: /* Leave setting as is */
92 break;
93
94 case PNG_CRC_WARN_USE: /* Warn/use data */
95 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
96 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE;
97 break;
98
99 case PNG_CRC_QUIET_USE: /* Quiet/use data */
100 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
101 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE |
102 PNG_FLAG_CRC_ANCILLARY_NOWARN;
103 break;
104
105 case PNG_CRC_ERROR_QUIT: /* Error/quit */
106 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
107 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN;
108 break;
109
110 case PNG_CRC_WARN_DISCARD: /* Warn/discard data */
111
112 case PNG_CRC_DEFAULT:
113 default:
114 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
115 break;
116 }
117 }
118
119 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
120 /* Is it OK to set a transformation now? Only if png_start_read_image or
121 * png_read_update_info have not been called. It is not necessary for the IHDR
122 * to have been read in all cases; the need_IHDR parameter allows for this
123 * check too.
124 */
125 static int
126 png_rtran_ok(png_structrp png_ptr, int need_IHDR)
127 {
128 if (png_ptr != NULL)
129 {
130 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) != 0)
131 png_app_error(png_ptr,
132 "invalid after png_start_read_image or png_read_update_info");
133
134 else if (need_IHDR && (png_ptr->mode & PNG_HAVE_IHDR) == 0)
135 png_app_error(png_ptr, "invalid before the PNG header has been read");
136
137 else
138 {
139 /* Turn on failure to initialize correctly for all transforms. */
140 png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED;
141
142 return 1; /* Ok */
143 }
144 }
145
146 return 0; /* no png_error possible! */
147 }
148 #endif
149
150 #ifdef PNG_READ_BACKGROUND_SUPPORTED
151 /* Handle alpha and tRNS via a background color */
152 void PNGFAPI
153 png_set_background_fixed(png_structrp png_ptr,
154 png_const_color_16p background_color, int background_gamma_code,
155 int need_expand, png_fixed_point background_gamma)
156 {
157 png_debug(1, "in png_set_background_fixed");
158
159 if (png_rtran_ok(png_ptr, 0) == 0 || background_color == NULL)
160 return;
161
162 if (background_gamma_code == PNG_BACKGROUND_GAMMA_UNKNOWN)
163 {
164 png_warning(png_ptr, "Application must supply a known background gamma");
165 return;
166 }
167
168 png_ptr->transformations |= PNG_COMPOSE | PNG_STRIP_ALPHA;
169 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
170 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
171
172 png_ptr->background = *background_color;
173 png_ptr->background_gamma = background_gamma;
174 png_ptr->background_gamma_type = (png_byte)(background_gamma_code);
175 if (need_expand != 0)
176 png_ptr->transformations |= PNG_BACKGROUND_EXPAND;
177 else
178 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
179 }
180
181 # ifdef PNG_FLOATING_POINT_SUPPORTED
182 void PNGAPI
183 png_set_background(png_structrp png_ptr,
184 png_const_color_16p background_color, int background_gamma_code,
185 int need_expand, double background_gamma)
186 {
187 png_set_background_fixed(png_ptr, background_color, background_gamma_code,
188 need_expand, png_fixed(png_ptr, background_gamma, "png_set_background"));
189 }
190 # endif /* FLOATING_POINT */
191 #endif /* READ_BACKGROUND */
192
193 /* Scale 16-bit depth files to 8-bit depth. If both of these are set then the
194 * one that pngrtran does first (scale) happens. This is necessary to allow the
195 * TRANSFORM and API behavior to be somewhat consistent, and it's simpler.
196 */
197 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
198 void PNGAPI
199 png_set_scale_16(png_structrp png_ptr)
200 {
201 png_debug(1, "in png_set_scale_16");
202
203 if (png_rtran_ok(png_ptr, 0) == 0)
204 return;
205
206 png_ptr->transformations |= PNG_SCALE_16_TO_8;
207 }
208 #endif
209
210 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
211 /* Chop 16-bit depth files to 8-bit depth */
212 void PNGAPI
213 png_set_strip_16(png_structrp png_ptr)
214 {
215 png_debug(1, "in png_set_strip_16");
216
217 if (png_rtran_ok(png_ptr, 0) == 0)
218 return;
219
220 png_ptr->transformations |= PNG_16_TO_8;
221 }
222 #endif
223
224 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
225 void PNGAPI
226 png_set_strip_alpha(png_structrp png_ptr)
227 {
228 png_debug(1, "in png_set_strip_alpha");
229
230 if (png_rtran_ok(png_ptr, 0) == 0)
231 return;
232
233 png_ptr->transformations |= PNG_STRIP_ALPHA;
234 }
235 #endif
236
237 #if defined(PNG_READ_ALPHA_MODE_SUPPORTED) || defined(PNG_READ_GAMMA_SUPPORTED)
238 static png_fixed_point
239 translate_gamma_flags(png_structrp png_ptr, png_fixed_point output_gamma,
240 int is_screen)
241 {
242 /* Check for flag values. The main reason for having the old Mac value as a
243 * flag is that it is pretty near impossible to work out what the correct
244 * value is from Apple documentation - a working Mac system is needed to
245 * discover the value!
246 */
247 if (output_gamma == PNG_DEFAULT_sRGB ||
248 output_gamma == PNG_FP_1 / PNG_DEFAULT_sRGB)
249 {
250 /* If there is no sRGB support this just sets the gamma to the standard
251 * sRGB value. (This is a side effect of using this function!)
252 */
253 # ifdef PNG_READ_sRGB_SUPPORTED
254 png_ptr->flags |= PNG_FLAG_ASSUME_sRGB;
255 # else
256 PNG_UNUSED(png_ptr)
257 # endif
258 if (is_screen != 0)
259 output_gamma = PNG_GAMMA_sRGB;
260 else
261 output_gamma = PNG_GAMMA_sRGB_INVERSE;
262 }
263
264 else if (output_gamma == PNG_GAMMA_MAC_18 ||
265 output_gamma == PNG_FP_1 / PNG_GAMMA_MAC_18)
266 {
267 if (is_screen != 0)
268 output_gamma = PNG_GAMMA_MAC_OLD;
269 else
270 output_gamma = PNG_GAMMA_MAC_INVERSE;
271 }
272
273 return output_gamma;
274 }
275
276 # ifdef PNG_FLOATING_POINT_SUPPORTED
277 static png_fixed_point
278 convert_gamma_value(png_structrp png_ptr, double output_gamma)
279 {
280 /* The following silently ignores cases where fixed point (times 100,000)
281 * gamma values are passed to the floating point API. This is safe and it
282 * means the fixed point constants work just fine with the floating point
283 * API. The alternative would just lead to undetected errors and spurious
284 * bug reports. Negative values fail inside the _fixed API unless they
285 * correspond to the flag values.
286 */
287 if (output_gamma > 0 && output_gamma < 128)
288 output_gamma *= PNG_FP_1;
289
290 /* This preserves -1 and -2 exactly: */
291 output_gamma = floor(output_gamma + .5);
292
293 if (output_gamma > PNG_FP_MAX || output_gamma < PNG_FP_MIN)
294 png_fixed_error(png_ptr, "gamma value");
295
296 return (png_fixed_point)output_gamma;
297 }
298 # endif
299 #endif /* READ_ALPHA_MODE || READ_GAMMA */
300
301 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
302 void PNGFAPI
303 png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,
304 png_fixed_point output_gamma)
305 {
306 int compose = 0;
307 png_fixed_point file_gamma;
308
309 png_debug(1, "in png_set_alpha_mode");
310
311 if (png_rtran_ok(png_ptr, 0) == 0)
312 return;
313
314 output_gamma = translate_gamma_flags(png_ptr, output_gamma, 1/*screen*/);
315
316 /* Validate the value to ensure it is in a reasonable range. The value
317 * is expected to be 1 or greater, but this range test allows for some
318 * viewing correction values. The intent is to weed out users of this API
319 * who use the inverse of the gamma value accidentally! Since some of these
320 * values are reasonable this may have to be changed.
321 */
322 if (output_gamma < 70000 || output_gamma > 300000)
323 png_error(png_ptr, "output gamma out of expected range");
324
325 /* The default file gamma is the inverse of the output gamma; the output
326 * gamma may be changed below so get the file value first:
327 */
328 file_gamma = png_reciprocal(output_gamma);
329
330 /* There are really 8 possibilities here, composed of any combination
331 * of:
332 *
333 * premultiply the color channels
334 * do not encode non-opaque pixels
335 * encode the alpha as well as the color channels
336 *
337 * The differences disappear if the input/output ('screen') gamma is 1.0,
338 * because then the encoding is a no-op and there is only the choice of
339 * premultiplying the color channels or not.
340 *
341 * png_set_alpha_mode and png_set_background interact because both use
342 * png_compose to do the work. Calling both is only useful when
343 * png_set_alpha_mode is used to set the default mode - PNG_ALPHA_PNG - along
344 * with a default gamma value. Otherwise PNG_COMPOSE must not be set.
345 */
346 switch (mode)
347 {
348 case PNG_ALPHA_PNG: /* default: png standard */
349 /* No compose, but it may be set by png_set_background! */
350 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
351 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
352 break;
353
354 case PNG_ALPHA_ASSOCIATED: /* color channels premultiplied */
355 compose = 1;
356 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
357 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
358 /* The output is linear: */
359 output_gamma = PNG_FP_1;
360 break;
361
362 case PNG_ALPHA_OPTIMIZED: /* associated, non-opaque pixels linear */
363 compose = 1;
364 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
365 png_ptr->flags |= PNG_FLAG_OPTIMIZE_ALPHA;
366 /* output_gamma records the encoding of opaque pixels! */
367 break;
368
369 case PNG_ALPHA_BROKEN: /* associated, non-linear, alpha encoded */
370 compose = 1;
371 png_ptr->transformations |= PNG_ENCODE_ALPHA;
372 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
373 break;
374
375 default:
376 png_error(png_ptr, "invalid alpha mode");
377 }
378
379 /* Only set the default gamma if the file gamma has not been set (this has
380 * the side effect that the gamma in a second call to png_set_alpha_mode will
381 * be ignored.)
382 */
383 if (png_ptr->colorspace.gamma == 0)
384 {
385 png_ptr->colorspace.gamma = file_gamma;
386 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
387 }
388
389 /* But always set the output gamma: */
390 png_ptr->screen_gamma = output_gamma;
391
392 /* Finally, if pre-multiplying, set the background fields to achieve the
393 * desired result.
394 */
395 if (compose != 0)
396 {
397 /* And obtain alpha pre-multiplication by composing on black: */
398 memset(&png_ptr->background, 0, (sizeof png_ptr->background));
399 png_ptr->background_gamma = png_ptr->colorspace.gamma; /* just in case */
400 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_FILE;
401 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
402
403 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
404 png_error(png_ptr,
405 "conflicting calls to set alpha mode and background");
406
407 png_ptr->transformations |= PNG_COMPOSE;
408 }
409 }
410
411 # ifdef PNG_FLOATING_POINT_SUPPORTED
412 void PNGAPI
413 png_set_alpha_mode(png_structrp png_ptr, int mode, double output_gamma)
414 {
415 png_set_alpha_mode_fixed(png_ptr, mode, convert_gamma_value(png_ptr,
416 output_gamma));
417 }
418 # endif
419 #endif
420
421 #ifdef PNG_READ_QUANTIZE_SUPPORTED
422 /* Dither file to 8-bit. Supply a palette, the current number
423 * of elements in the palette, the maximum number of elements
424 * allowed, and a histogram if possible. If the current number
425 * of colors is greater then the maximum number, the palette will be
426 * modified to fit in the maximum number. "full_quantize" indicates
427 * whether we need a quantizing cube set up for RGB images, or if we
428 * simply are reducing the number of colors in a paletted image.
429 */
430
431 typedef struct png_dsort_struct
432 {
433 struct png_dsort_struct * next;
434 png_byte left;
435 png_byte right;
436 } png_dsort;
437 typedef png_dsort * png_dsortp;
438 typedef png_dsort * * png_dsortpp;
439
440 void PNGAPI
441 png_set_quantize(png_structrp png_ptr, png_colorp palette,
442 int num_palette, int maximum_colors, png_const_uint_16p histogram,
443 int full_quantize)
444 {
445 png_debug(1, "in png_set_quantize");
446
447 if (png_rtran_ok(png_ptr, 0) == 0)
448 return;
449
450 png_ptr->transformations |= PNG_QUANTIZE;
451
452 if (full_quantize == 0)
453 {
454 int i;
455
456 png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr,
457 (png_uint_32)(num_palette * (sizeof (png_byte))));
458 for (i = 0; i < num_palette; i++)
459 png_ptr->quantize_index[i] = (png_byte)i;
460 }
461
462 if (num_palette > maximum_colors)
463 {
464 if (histogram != NULL)
465 {
466 /* This is easy enough, just throw out the least used colors.
467 * Perhaps not the best solution, but good enough.
468 */
469
470 int i;
471
472 /* Initialize an array to sort colors */
473 png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr,
474 (png_uint_32)(num_palette * (sizeof (png_byte))));
475
476 /* Initialize the quantize_sort array */
477 for (i = 0; i < num_palette; i++)
478 png_ptr->quantize_sort[i] = (png_byte)i;
479
480 /* Find the least used palette entries by starting a
481 * bubble sort, and running it until we have sorted
482 * out enough colors. Note that we don't care about
483 * sorting all the colors, just finding which are
484 * least used.
485 */
486
487 for (i = num_palette - 1; i >= maximum_colors; i--)
488 {
489 int done; /* To stop early if the list is pre-sorted */
490 int j;
491
492 done = 1;
493 for (j = 0; j < i; j++)
494 {
495 if (histogram[png_ptr->quantize_sort[j]]
496 < histogram[png_ptr->quantize_sort[j + 1]])
497 {
498 png_byte t;
499
500 t = png_ptr->quantize_sort[j];
501 png_ptr->quantize_sort[j] = png_ptr->quantize_sort[j + 1];
502 png_ptr->quantize_sort[j + 1] = t;
503 done = 0;
504 }
505 }
506
507 if (done != 0)
508 break;
509 }
510
511 /* Swap the palette around, and set up a table, if necessary */
512 if (full_quantize != 0)
513 {
514 int j = num_palette;
515
516 /* Put all the useful colors within the max, but don't
517 * move the others.
518 */
519 for (i = 0; i < maximum_colors; i++)
520 {
521 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
522 {
523 do
524 j--;
525 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
526
527 palette[i] = palette[j];
528 }
529 }
530 }
531 else
532 {
533 int j = num_palette;
534
535 /* Move all the used colors inside the max limit, and
536 * develop a translation table.
537 */
538 for (i = 0; i < maximum_colors; i++)
539 {
540 /* Only move the colors we need to */
541 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
542 {
543 png_color tmp_color;
544
545 do
546 j--;
547 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
548
549 tmp_color = palette[j];
550 palette[j] = palette[i];
551 palette[i] = tmp_color;
552 /* Indicate where the color went */
553 png_ptr->quantize_index[j] = (png_byte)i;
554 png_ptr->quantize_index[i] = (png_byte)j;
555 }
556 }
557
558 /* Find closest color for those colors we are not using */
559 for (i = 0; i < num_palette; i++)
560 {
561 if ((int)png_ptr->quantize_index[i] >= maximum_colors)
562 {
563 int min_d, k, min_k, d_index;
564
565 /* Find the closest color to one we threw out */
566 d_index = png_ptr->quantize_index[i];
567 min_d = PNG_COLOR_DIST(palette[d_index], palette[0]);
568 for (k = 1, min_k = 0; k < maximum_colors; k++)
569 {
570 int d;
571
572 d = PNG_COLOR_DIST(palette[d_index], palette[k]);
573
574 if (d < min_d)
575 {
576 min_d = d;
577 min_k = k;
578 }
579 }
580 /* Point to closest color */
581 png_ptr->quantize_index[i] = (png_byte)min_k;
582 }
583 }
584 }
585 png_free(png_ptr, png_ptr->quantize_sort);
586 png_ptr->quantize_sort = NULL;
587 }
588 else
589 {
590 /* This is much harder to do simply (and quickly). Perhaps
591 * we need to go through a median cut routine, but those
592 * don't always behave themselves with only a few colors
593 * as input. So we will just find the closest two colors,
594 * and throw out one of them (chosen somewhat randomly).
595 * [We don't understand this at all, so if someone wants to
596 * work on improving it, be our guest - AED, GRP]
597 */
598 int i;
599 int max_d;
600 int num_new_palette;
601 png_dsortp t;
602 png_dsortpp hash;
603
604 t = NULL;
605
606 /* Initialize palette index arrays */
607 png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr,
608 (png_uint_32)(num_palette * (sizeof (png_byte))));
609 png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr,
610 (png_uint_32)(num_palette * (sizeof (png_byte))));
611
612 /* Initialize the sort array */
613 for (i = 0; i < num_palette; i++)
614 {
615 png_ptr->index_to_palette[i] = (png_byte)i;
616 png_ptr->palette_to_index[i] = (png_byte)i;
617 }
618
619 hash = (png_dsortpp)png_calloc(png_ptr, (png_uint_32)(769 *
620 (sizeof (png_dsortp))));
621
622 num_new_palette = num_palette;
623
624 /* Initial wild guess at how far apart the farthest pixel
625 * pair we will be eliminating will be. Larger
626 * numbers mean more areas will be allocated, Smaller
627 * numbers run the risk of not saving enough data, and
628 * having to do this all over again.
629 *
630 * I have not done extensive checking on this number.
631 */
632 max_d = 96;
633
634 while (num_new_palette > maximum_colors)
635 {
636 for (i = 0; i < num_new_palette - 1; i++)
637 {
638 int j;
639
640 for (j = i + 1; j < num_new_palette; j++)
641 {
642 int d;
643
644 d = PNG_COLOR_DIST(palette[i], palette[j]);
645
646 if (d <= max_d)
647 {
648
649 t = (png_dsortp)png_malloc_warn(png_ptr,
650 (png_uint_32)(sizeof (png_dsort)));
651
652 if (t == NULL)
653 break;
654
655 t->next = hash[d];
656 t->left = (png_byte)i;
657 t->right = (png_byte)j;
658 hash[d] = t;
659 }
660 }
661 if (t == NULL)
662 break;
663 }
664
665 if (t != NULL)
666 for (i = 0; i <= max_d; i++)
667 {
668 if (hash[i] != NULL)
669 {
670 png_dsortp p;
671
672 for (p = hash[i]; p; p = p->next)
673 {
674 if ((int)png_ptr->index_to_palette[p->left]
675 < num_new_palette &&
676 (int)png_ptr->index_to_palette[p->right]
677 < num_new_palette)
678 {
679 int j, next_j;
680
681 if (num_new_palette & 0x01)
682 {
683 j = p->left;
684 next_j = p->right;
685 }
686 else
687 {
688 j = p->right;
689 next_j = p->left;
690 }
691
692 num_new_palette--;
693 palette[png_ptr->index_to_palette[j]]
694 = palette[num_new_palette];
695 if (full_quantize == 0)
696 {
697 int k;
698
699 for (k = 0; k < num_palette; k++)
700 {
701 if (png_ptr->quantize_index[k] ==
702 png_ptr->index_to_palette[j])
703 png_ptr->quantize_index[k] =
704 png_ptr->index_to_palette[next_j];
705
706 if ((int)png_ptr->quantize_index[k] ==
707 num_new_palette)
708 png_ptr->quantize_index[k] =
709 png_ptr->index_to_palette[j];
710 }
711 }
712
713 png_ptr->index_to_palette[png_ptr->palette_to_index
714 [num_new_palette]] = png_ptr->index_to_palette[j];
715
716 png_ptr->palette_to_index[png_ptr->index_to_palette[j]]
717 = png_ptr->palette_to_index[num_new_palette];
718
719 png_ptr->index_to_palette[j] =
720 (png_byte)num_new_palette;
721
722 png_ptr->palette_to_index[num_new_palette] =
723 (png_byte)j;
724 }
725 if (num_new_palette <= maximum_colors)
726 break;
727 }
728 if (num_new_palette <= maximum_colors)
729 break;
730 }
731 }
732
733 for (i = 0; i < 769; i++)
734 {
735 if (hash[i] != NULL)
736 {
737 png_dsortp p = hash[i];
738 while (p)
739 {
740 t = p->next;
741 png_free(png_ptr, p);
742 p = t;
743 }
744 }
745 hash[i] = 0;
746 }
747 max_d += 96;
748 }
749 png_free(png_ptr, hash);
750 png_free(png_ptr, png_ptr->palette_to_index);
751 png_free(png_ptr, png_ptr->index_to_palette);
752 png_ptr->palette_to_index = NULL;
753 png_ptr->index_to_palette = NULL;
754 }
755 num_palette = maximum_colors;
756 }
757 if (png_ptr->palette == NULL)
758 {
759 png_ptr->palette = palette;
760 }
761 png_ptr->num_palette = (png_uint_16)num_palette;
762
763 if (full_quantize != 0)
764 {
765 int i;
766 png_bytep distance;
767 int total_bits = PNG_QUANTIZE_RED_BITS + PNG_QUANTIZE_GREEN_BITS +
768 PNG_QUANTIZE_BLUE_BITS;
769 int num_red = (1 << PNG_QUANTIZE_RED_BITS);
770 int num_green = (1 << PNG_QUANTIZE_GREEN_BITS);
771 int num_blue = (1 << PNG_QUANTIZE_BLUE_BITS);
772 png_size_t num_entries = ((png_size_t)1 << total_bits);
773
774 png_ptr->palette_lookup = (png_bytep)png_calloc(png_ptr,
775 (png_uint_32)(num_entries * (sizeof (png_byte))));
776
777 distance = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_entries *
778 (sizeof (png_byte))));
779
780 memset(distance, 0xff, num_entries * (sizeof (png_byte)));
781
782 for (i = 0; i < num_palette; i++)
783 {
784 int ir, ig, ib;
785 int r = (palette[i].red >> (8 - PNG_QUANTIZE_RED_BITS));
786 int g = (palette[i].green >> (8 - PNG_QUANTIZE_GREEN_BITS));
787 int b = (palette[i].blue >> (8 - PNG_QUANTIZE_BLUE_BITS));
788
789 for (ir = 0; ir < num_red; ir++)
790 {
791 /* int dr = abs(ir - r); */
792 int dr = ((ir > r) ? ir - r : r - ir);
793 int index_r = (ir << (PNG_QUANTIZE_BLUE_BITS +
794 PNG_QUANTIZE_GREEN_BITS));
795
796 for (ig = 0; ig < num_green; ig++)
797 {
798 /* int dg = abs(ig - g); */
799 int dg = ((ig > g) ? ig - g : g - ig);
800 int dt = dr + dg;
801 int dm = ((dr > dg) ? dr : dg);
802 int index_g = index_r | (ig << PNG_QUANTIZE_BLUE_BITS);
803
804 for (ib = 0; ib < num_blue; ib++)
805 {
806 int d_index = index_g | ib;
807 /* int db = abs(ib - b); */
808 int db = ((ib > b) ? ib - b : b - ib);
809 int dmax = ((dm > db) ? dm : db);
810 int d = dmax + dt + db;
811
812 if (d < (int)distance[d_index])
813 {
814 distance[d_index] = (png_byte)d;
815 png_ptr->palette_lookup[d_index] = (png_byte)i;
816 }
817 }
818 }
819 }
820 }
821
822 png_free(png_ptr, distance);
823 }
824 }
825 #endif /* READ_QUANTIZE */
826
827 #ifdef PNG_READ_GAMMA_SUPPORTED
828 void PNGFAPI
829 png_set_gamma_fixed(png_structrp png_ptr, png_fixed_point scrn_gamma,
830 png_fixed_point file_gamma)
831 {
832 png_debug(1, "in png_set_gamma_fixed");
833
834 if (png_rtran_ok(png_ptr, 0) == 0)
835 return;
836
837 /* New in libpng-1.5.4 - reserve particular negative values as flags. */
838 scrn_gamma = translate_gamma_flags(png_ptr, scrn_gamma, 1/*screen*/);
839 file_gamma = translate_gamma_flags(png_ptr, file_gamma, 0/*file*/);
840
841 /* Checking the gamma values for being >0 was added in 1.5.4 along with the
842 * premultiplied alpha support; this actually hides an undocumented feature
843 * of the previous implementation which allowed gamma processing to be
844 * disabled in background handling. There is no evidence (so far) that this
845 * was being used; however, png_set_background itself accepted and must still
846 * accept '0' for the gamma value it takes, because it isn't always used.
847 *
848 * Since this is an API change (albeit a very minor one that removes an
849 * undocumented API feature) the following checks were only enabled in
850 * libpng-1.6.0.
851 */
852 if (file_gamma <= 0)
853 png_error(png_ptr, "invalid file gamma in png_set_gamma");
854
855 if (scrn_gamma <= 0)
856 png_error(png_ptr, "invalid screen gamma in png_set_gamma");
857
858 /* Set the gamma values unconditionally - this overrides the value in the PNG
859 * file if a gAMA chunk was present. png_set_alpha_mode provides a
860 * different, easier, way to default the file gamma.
861 */
862 png_ptr->colorspace.gamma = file_gamma;
863 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
864 png_ptr->screen_gamma = scrn_gamma;
865 }
866
867 # ifdef PNG_FLOATING_POINT_SUPPORTED
868 void PNGAPI
869 png_set_gamma(png_structrp png_ptr, double scrn_gamma, double file_gamma)
870 {
871 png_set_gamma_fixed(png_ptr, convert_gamma_value(png_ptr, scrn_gamma),
872 convert_gamma_value(png_ptr, file_gamma));
873 }
874 # endif /* FLOATING_POINT */
875 #endif /* READ_GAMMA */
876
877 #ifdef PNG_READ_EXPAND_SUPPORTED
878 /* Expand paletted images to RGB, expand grayscale images of
879 * less than 8-bit depth to 8-bit depth, and expand tRNS chunks
880 * to alpha channels.
881 */
882 void PNGAPI
883 png_set_expand(png_structrp png_ptr)
884 {
885 png_debug(1, "in png_set_expand");
886
887 if (png_rtran_ok(png_ptr, 0) == 0)
888 return;
889
890 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
891 }
892
893 /* GRR 19990627: the following three functions currently are identical
894 * to png_set_expand(). However, it is entirely reasonable that someone
895 * might wish to expand an indexed image to RGB but *not* expand a single,
896 * fully transparent palette entry to a full alpha channel--perhaps instead
897 * convert tRNS to the grayscale/RGB format (16-bit RGB value), or replace
898 * the transparent color with a particular RGB value, or drop tRNS entirely.
899 * IOW, a future version of the library may make the transformations flag
900 * a bit more fine-grained, with separate bits for each of these three
901 * functions.
902 *
903 * More to the point, these functions make it obvious what libpng will be
904 * doing, whereas "expand" can (and does) mean any number of things.
905 *
906 * GRP 20060307: In libpng-1.2.9, png_set_gray_1_2_4_to_8() was modified
907 * to expand only the sample depth but not to expand the tRNS to alpha
908 * and its name was changed to png_set_expand_gray_1_2_4_to_8().
909 */
910
911 /* Expand paletted images to RGB. */
912 void PNGAPI
913 png_set_palette_to_rgb(png_structrp png_ptr)
914 {
915 png_debug(1, "in png_set_palette_to_rgb");
916
917 if (png_rtran_ok(png_ptr, 0) == 0)
918 return;
919
920 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
921 }
922
923 /* Expand grayscale images of less than 8-bit depth to 8 bits. */
924 void PNGAPI
925 png_set_expand_gray_1_2_4_to_8(png_structrp png_ptr)
926 {
927 png_debug(1, "in png_set_expand_gray_1_2_4_to_8");
928
929 if (png_rtran_ok(png_ptr, 0) == 0)
930 return;
931
932 png_ptr->transformations |= PNG_EXPAND;
933 }
934
935 /* Expand tRNS chunks to alpha channels. */
936 void PNGAPI
937 png_set_tRNS_to_alpha(png_structrp png_ptr)
938 {
939 png_debug(1, "in png_set_tRNS_to_alpha");
940
941 if (png_rtran_ok(png_ptr, 0) == 0)
942 return;
943
944 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
945 }
946 #endif /* READ_EXPAND */
947
948 #ifdef PNG_READ_EXPAND_16_SUPPORTED
949 /* Expand to 16-bit channels, expand the tRNS chunk too (because otherwise
950 * it may not work correctly.)
951 */
952 void PNGAPI
953 png_set_expand_16(png_structrp png_ptr)
954 {
955 png_debug(1, "in png_set_expand_16");
956
957 if (png_rtran_ok(png_ptr, 0) == 0)
958 return;
959
960 png_ptr->transformations |= (PNG_EXPAND_16 | PNG_EXPAND | PNG_EXPAND_tRNS);
961 }
962 #endif
963
964 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
965 void PNGAPI
966 png_set_gray_to_rgb(png_structrp png_ptr)
967 {
968 png_debug(1, "in png_set_gray_to_rgb");
969
970 if (png_rtran_ok(png_ptr, 0) == 0)
971 return;
972
973 /* Because rgb must be 8 bits or more: */
974 png_set_expand_gray_1_2_4_to_8(png_ptr);
975 png_ptr->transformations |= PNG_GRAY_TO_RGB;
976 }
977 #endif
978
979 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
980 void PNGFAPI
981 png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action,
982 png_fixed_point red, png_fixed_point green)
983 {
984 png_debug(1, "in png_set_rgb_to_gray");
985
986 /* Need the IHDR here because of the check on color_type below. */
987 /* TODO: fix this */
988 if (png_rtran_ok(png_ptr, 1) == 0)
989 return;
990
991 switch (error_action)
992 {
993 case PNG_ERROR_ACTION_NONE:
994 png_ptr->transformations |= PNG_RGB_TO_GRAY;
995 break;
996
997 case PNG_ERROR_ACTION_WARN:
998 png_ptr->transformations |= PNG_RGB_TO_GRAY_WARN;
999 break;
1000
1001 case PNG_ERROR_ACTION_ERROR:
1002 png_ptr->transformations |= PNG_RGB_TO_GRAY_ERR;
1003 break;
1004
1005 default:
1006 png_error(png_ptr, "invalid error action to rgb_to_gray");
1007 break;
1008 }
1009
1010 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1011 #ifdef PNG_READ_EXPAND_SUPPORTED
1012 png_ptr->transformations |= PNG_EXPAND;
1013 #else
1014 {
1015 /* Make this an error in 1.6 because otherwise the application may assume
1016 * that it just worked and get a memory overwrite.
1017 */
1018 png_error(png_ptr,
1019 "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED");
1020
1021 /* png_ptr->transformations &= ~PNG_RGB_TO_GRAY; */
1022 }
1023 #endif
1024 {
1025 if (red >= 0 && green >= 0 && red + green <= PNG_FP_1)
1026 {
1027 png_uint_16 red_int, green_int;
1028
1029 /* NOTE: this calculation does not round, but this behavior is retained
1030 * for consistency; the inaccuracy is very small. The code here always
1031 * overwrites the coefficients, regardless of whether they have been
1032 * defaulted or set already.
1033 */
1034 red_int = (png_uint_16)(((png_uint_32)red*32768)/100000);
1035 green_int = (png_uint_16)(((png_uint_32)green*32768)/100000);
1036
1037 png_ptr->rgb_to_gray_red_coeff = red_int;
1038 png_ptr->rgb_to_gray_green_coeff = green_int;
1039 png_ptr->rgb_to_gray_coefficients_set = 1;
1040 }
1041
1042 else
1043 {
1044 if (red >= 0 && green >= 0)
1045 png_app_warning(png_ptr,
1046 "ignoring out of range rgb_to_gray coefficients");
1047
1048 /* Use the defaults, from the cHRM chunk if set, else the historical
1049 * values which are close to the sRGB/HDTV/ITU-Rec 709 values. See
1050 * png_do_rgb_to_gray for more discussion of the values. In this case
1051 * the coefficients are not marked as 'set' and are not overwritten if
1052 * something has already provided a default.
1053 */
1054 if (png_ptr->rgb_to_gray_red_coeff == 0 &&
1055 png_ptr->rgb_to_gray_green_coeff == 0)
1056 {
1057 png_ptr->rgb_to_gray_red_coeff = 6968;
1058 png_ptr->rgb_to_gray_green_coeff = 23434;
1059 /* png_ptr->rgb_to_gray_blue_coeff = 2366; */
1060 }
1061 }
1062 }
1063 }
1064
1065 #ifdef PNG_FLOATING_POINT_SUPPORTED
1066 /* Convert a RGB image to a grayscale of the same width. This allows us,
1067 * for example, to convert a 24 bpp RGB image into an 8 bpp grayscale image.
1068 */
1069
1070 void PNGAPI
1071 png_set_rgb_to_gray(png_structrp png_ptr, int error_action, double red,
1072 double green)
1073 {
1074 png_set_rgb_to_gray_fixed(png_ptr, error_action,
1075 png_fixed(png_ptr, red, "rgb to gray red coefficient"),
1076 png_fixed(png_ptr, green, "rgb to gray green coefficient"));
1077 }
1078 #endif /* FLOATING POINT */
1079
1080 #endif /* RGB_TO_GRAY */
1081
1082 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
1083 defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
1084 void PNGAPI
1085 png_set_read_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr
1086 read_user_transform_fn)
1087 {
1088 png_debug(1, "in png_set_read_user_transform_fn");
1089
1090 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
1091 png_ptr->transformations |= PNG_USER_TRANSFORM;
1092 png_ptr->read_user_transform_fn = read_user_transform_fn;
1093 #endif
1094 }
1095 #endif
1096
1097 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
1098 #ifdef PNG_READ_GAMMA_SUPPORTED
1099 /* In the case of gamma transformations only do transformations on images where
1100 * the [file] gamma and screen_gamma are not close reciprocals, otherwise it
1101 * slows things down slightly, and also needlessly introduces small errors.
1102 */
1103 static int /* PRIVATE */
1104 png_gamma_threshold(png_fixed_point screen_gamma, png_fixed_point file_gamma)
1105 {
1106 /* PNG_GAMMA_THRESHOLD is the threshold for performing gamma
1107 * correction as a difference of the overall transform from 1.0
1108 *
1109 * We want to compare the threshold with s*f - 1, if we get
1110 * overflow here it is because of wacky gamma values so we
1111 * turn on processing anyway.
1112 */
1113 png_fixed_point gtest;
1114 return !png_muldiv(>est, screen_gamma, file_gamma, PNG_FP_1) ||
1115 png_gamma_significant(gtest);
1116 }
1117 #endif
1118
1119 /* Initialize everything needed for the read. This includes modifying
1120 * the palette.
1121 */
1122
1123 /* For the moment 'png_init_palette_transformations' and
1124 * 'png_init_rgb_transformations' only do some flag canceling optimizations.
1125 * The intent is that these two routines should have palette or rgb operations
1126 * extracted from 'png_init_read_transformations'.
1127 */
1128 static void /* PRIVATE */
1129 png_init_palette_transformations(png_structrp png_ptr)
1130 {
1131 /* Called to handle the (input) palette case. In png_do_read_transformations
1132 * the first step is to expand the palette if requested, so this code must
1133 * take care to only make changes that are invariant with respect to the
1134 * palette expansion, or only do them if there is no expansion.
1135 *
1136 * STRIP_ALPHA has already been handled in the caller (by setting num_trans
1137 * to 0.)
1138 */
1139 int input_has_alpha = 0;
1140 int input_has_transparency = 0;
1141
1142 if (png_ptr->num_trans > 0)
1143 {
1144 int i;
1145
1146 /* Ignore if all the entries are opaque (unlikely!) */
1147 for (i=0; i<png_ptr->num_trans; ++i)
1148 {
1149 if (png_ptr->trans_alpha[i] == 255)
1150 continue;
1151 else if (png_ptr->trans_alpha[i] == 0)
1152 input_has_transparency = 1;
1153 else
1154 {
1155 input_has_transparency = 1;
1156 input_has_alpha = 1;
1157 break;
1158 }
1159 }
1160 }
1161
1162 /* If no alpha we can optimize. */
1163 if (input_has_alpha == 0)
1164 {
1165 /* Any alpha means background and associative alpha processing is
1166 * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
1167 * and ENCODE_ALPHA are irrelevant.
1168 */
1169 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1170 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1171
1172 if (input_has_transparency == 0)
1173 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1174 }
1175
1176 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1177 /* png_set_background handling - deals with the complexity of whether the
1178 * background color is in the file format or the screen format in the case
1179 * where an 'expand' will happen.
1180 */
1181
1182 /* The following code cannot be entered in the alpha pre-multiplication case
1183 * because PNG_BACKGROUND_EXPAND is cancelled below.
1184 */
1185 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
1186 (png_ptr->transformations & PNG_EXPAND) != 0)
1187 {
1188 {
1189 png_ptr->background.red =
1190 png_ptr->palette[png_ptr->background.index].red;
1191 png_ptr->background.green =
1192 png_ptr->palette[png_ptr->background.index].green;
1193 png_ptr->background.blue =
1194 png_ptr->palette[png_ptr->background.index].blue;
1195
1196 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1197 if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
1198 {
1199 if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
1200 {
1201 /* Invert the alpha channel (in tRNS) unless the pixels are
1202 * going to be expanded, in which case leave it for later
1203 */
1204 int i, istop = png_ptr->num_trans;
1205
1206 for (i=0; i<istop; i++)
1207 png_ptr->trans_alpha[i] = (png_byte)(255 -
1208 png_ptr->trans_alpha[i]);
1209 }
1210 }
1211 #endif /* READ_INVERT_ALPHA */
1212 }
1213 } /* background expand and (therefore) no alpha association. */
1214 #endif /* READ_EXPAND && READ_BACKGROUND */
1215 }
1216
1217 static void /* PRIVATE */
1218 png_init_rgb_transformations(png_structrp png_ptr)
1219 {
1220 /* Added to libpng-1.5.4: check the color type to determine whether there
1221 * is any alpha or transparency in the image and simply cancel the
1222 * background and alpha mode stuff if there isn't.
1223 */
1224 int input_has_alpha = (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0;
1225 int input_has_transparency = png_ptr->num_trans > 0;
1226
1227 /* If no alpha we can optimize. */
1228 if (input_has_alpha == 0)
1229 {
1230 /* Any alpha means background and associative alpha processing is
1231 * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
1232 * and ENCODE_ALPHA are irrelevant.
1233 */
1234 # ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1235 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1236 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1237 # endif
1238
1239 if (input_has_transparency == 0)
1240 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1241 }
1242
1243 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1244 /* png_set_background handling - deals with the complexity of whether the
1245 * background color is in the file format or the screen format in the case
1246 * where an 'expand' will happen.
1247 */
1248
1249 /* The following code cannot be entered in the alpha pre-multiplication case
1250 * because PNG_BACKGROUND_EXPAND is cancelled below.
1251 */
1252 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
1253 (png_ptr->transformations & PNG_EXPAND) != 0 &&
1254 (png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
1255 /* i.e., GRAY or GRAY_ALPHA */
1256 {
1257 {
1258 /* Expand background and tRNS chunks */
1259 int gray = png_ptr->background.gray;
1260 int trans_gray = png_ptr->trans_color.gray;
1261
1262 switch (png_ptr->bit_depth)
1263 {
1264 case 1:
1265 gray *= 0xff;
1266 trans_gray *= 0xff;
1267 break;
1268
1269 case 2:
1270 gray *= 0x55;
1271 trans_gray *= 0x55;
1272 break;
1273
1274 case 4:
1275 gray *= 0x11;
1276 trans_gray *= 0x11;
1277 break;
1278
1279 default:
1280
1281 case 8:
1282 /* FALL THROUGH (Already 8 bits) */
1283
1284 case 16:
1285 /* Already a full 16 bits */
1286 break;
1287 }
1288
1289 png_ptr->background.red = png_ptr->background.green =
1290 png_ptr->background.blue = (png_uint_16)gray;
1291
1292 if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
1293 {
1294 png_ptr->trans_color.red = png_ptr->trans_color.green =
1295 png_ptr->trans_color.blue = (png_uint_16)trans_gray;
1296 }
1297 }
1298 } /* background expand and (therefore) no alpha association. */
1299 #endif /* READ_EXPAND && READ_BACKGROUND */
1300 }
1301
1302 void /* PRIVATE */
1303 png_init_read_transformations(png_structrp png_ptr)
1304 {
1305 png_debug(1, "in png_init_read_transformations");
1306
1307 /* This internal function is called from png_read_start_row in pngrutil.c
1308 * and it is called before the 'rowbytes' calculation is done, so the code
1309 * in here can change or update the transformations flags.
1310 *
1311 * First do updates that do not depend on the details of the PNG image data
1312 * being processed.
1313 */
1314
1315 #ifdef PNG_READ_GAMMA_SUPPORTED
1316 /* Prior to 1.5.4 these tests were performed from png_set_gamma, 1.5.4 adds
1317 * png_set_alpha_mode and this is another source for a default file gamma so
1318 * the test needs to be performed later - here. In addition prior to 1.5.4
1319 * the tests were repeated for the PALETTE color type here - this is no
1320 * longer necessary (and doesn't seem to have been necessary before.)
1321 */
1322 {
1323 /* The following temporary indicates if overall gamma correction is
1324 * required.
1325 */
1326 int gamma_correction = 0;
1327
1328 if (png_ptr->colorspace.gamma != 0) /* has been set */
1329 {
1330 if (png_ptr->screen_gamma != 0) /* screen set too */
1331 gamma_correction = png_gamma_threshold(png_ptr->colorspace.gamma,
1332 png_ptr->screen_gamma);
1333
1334 else
1335 /* Assume the output matches the input; a long time default behavior
1336 * of libpng, although the standard has nothing to say about this.
1337 */
1338 png_ptr->screen_gamma = png_reciprocal(png_ptr->colorspace.gamma);
1339 }
1340
1341 else if (png_ptr->screen_gamma != 0)
1342 /* The converse - assume the file matches the screen, note that this
1343 * perhaps undesireable default can (from 1.5.4) be changed by calling
1344 * png_set_alpha_mode (even if the alpha handling mode isn't required
1345 * or isn't changed from the default.)
1346 */
1347 png_ptr->colorspace.gamma = png_reciprocal(png_ptr->screen_gamma);
1348
1349 else /* neither are set */
1350 /* Just in case the following prevents any processing - file and screen
1351 * are both assumed to be linear and there is no way to introduce a
1352 * third gamma value other than png_set_background with 'UNIQUE', and,
1353 * prior to 1.5.4
1354 */
1355 png_ptr->screen_gamma = png_ptr->colorspace.gamma = PNG_FP_1;
1356
1357 /* We have a gamma value now. */
1358 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
1359
1360 /* Now turn the gamma transformation on or off as appropriate. Notice
1361 * that PNG_GAMMA just refers to the file->screen correction. Alpha
1362 * composition may independently cause gamma correction because it needs
1363 * linear data (e.g. if the file has a gAMA chunk but the screen gamma
1364 * hasn't been specified.) In any case this flag may get turned off in
1365 * the code immediately below if the transform can be handled outside the
1366 * row loop.
1367 */
1368 if (gamma_correction != 0)
1369 png_ptr->transformations |= PNG_GAMMA;
1370
1371 else
1372 png_ptr->transformations &= ~PNG_GAMMA;
1373 }
1374 #endif
1375
1376 /* Certain transformations have the effect of preventing other
1377 * transformations that happen afterward in png_do_read_transformations;
1378 * resolve the interdependencies here. From the code of
1379 * png_do_read_transformations the order is:
1380 *
1381 * 1) PNG_EXPAND (including PNG_EXPAND_tRNS)
1382 * 2) PNG_STRIP_ALPHA (if no compose)
1383 * 3) PNG_RGB_TO_GRAY
1384 * 4) PNG_GRAY_TO_RGB iff !PNG_BACKGROUND_IS_GRAY
1385 * 5) PNG_COMPOSE
1386 * 6) PNG_GAMMA
1387 * 7) PNG_STRIP_ALPHA (if compose)
1388 * 8) PNG_ENCODE_ALPHA
1389 * 9) PNG_SCALE_16_TO_8
1390 * 10) PNG_16_TO_8
1391 * 11) PNG_QUANTIZE (converts to palette)
1392 * 12) PNG_EXPAND_16
1393 * 13) PNG_GRAY_TO_RGB iff PNG_BACKGROUND_IS_GRAY
1394 * 14) PNG_INVERT_MONO
1395 * 15) PNG_INVERT_ALPHA
1396 * 16) PNG_SHIFT
1397 * 17) PNG_PACK
1398 * 18) PNG_BGR
1399 * 19) PNG_PACKSWAP
1400 * 20) PNG_FILLER (includes PNG_ADD_ALPHA)
1401 * 21) PNG_SWAP_ALPHA
1402 * 22) PNG_SWAP_BYTES
1403 * 23) PNG_USER_TRANSFORM [must be last]
1404 */
1405 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1406 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
1407 (png_ptr->transformations & PNG_COMPOSE) == 0)
1408 {
1409 /* Stripping the alpha channel happens immediately after the 'expand'
1410 * transformations, before all other transformation, so it cancels out
1411 * the alpha handling. It has the side effect negating the effect of
1412 * PNG_EXPAND_tRNS too:
1413 */
1414 png_ptr->transformations &= ~(PNG_BACKGROUND_EXPAND | PNG_ENCODE_ALPHA |
1415 PNG_EXPAND_tRNS);
1416 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1417
1418 /* Kill the tRNS chunk itself too. Prior to 1.5.4 this did not happen
1419 * so transparency information would remain just so long as it wasn't
1420 * expanded. This produces unexpected API changes if the set of things
1421 * that do PNG_EXPAND_tRNS changes (perfectly possible given the
1422 * documentation - which says ask for what you want, accept what you
1423 * get.) This makes the behavior consistent from 1.5.4:
1424 */
1425 png_ptr->num_trans = 0;
1426 }
1427 #endif /* STRIP_ALPHA supported, no COMPOSE */
1428
1429 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1430 /* If the screen gamma is about 1.0 then the OPTIMIZE_ALPHA and ENCODE_ALPHA
1431 * settings will have no effect.
1432 */
1433 if (png_gamma_significant(png_ptr->screen_gamma) == 0)
1434 {
1435 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1436 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1437 }
1438 #endif
1439
1440 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1441 /* Make sure the coefficients for the rgb to gray conversion are set
1442 * appropriately.
1443 */
1444 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
1445 png_colorspace_set_rgb_coefficients(png_ptr);
1446 #endif
1447
1448 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1449 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1450 /* Detect gray background and attempt to enable optimization for
1451 * gray --> RGB case.
1452 *
1453 * Note: if PNG_BACKGROUND_EXPAND is set and color_type is either RGB or
1454 * RGB_ALPHA (in which case need_expand is superfluous anyway), the
1455 * background color might actually be gray yet not be flagged as such.
1456 * This is not a problem for the current code, which uses
1457 * PNG_BACKGROUND_IS_GRAY only to decide when to do the
1458 * png_do_gray_to_rgb() transformation.
1459 *
1460 * TODO: this code needs to be revised to avoid the complexity and
1461 * interdependencies. The color type of the background should be recorded in
1462 * png_set_background, along with the bit depth, then the code has a record
1463 * of exactly what color space the background is currently in.
1464 */
1465 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0)
1466 {
1467 /* PNG_BACKGROUND_EXPAND: the background is in the file color space, so if
1468 * the file was grayscale the background value is gray.
1469 */
1470 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
1471 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1472 }
1473
1474 else if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1475 {
1476 /* PNG_COMPOSE: png_set_background was called with need_expand false,
1477 * so the color is in the color space of the output or png_set_alpha_mode
1478 * was called and the color is black. Ignore RGB_TO_GRAY because that
1479 * happens before GRAY_TO_RGB.
1480 */
1481 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
1482 {
1483 if (png_ptr->background.red == png_ptr->background.green &&
1484 png_ptr->background.red == png_ptr->background.blue)
1485 {
1486 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1487 png_ptr->background.gray = png_ptr->background.red;
1488 }
1489 }
1490 }
1491 #endif /* READ_EXPAND && READ_BACKGROUND */
1492 #endif /* READ_GRAY_TO_RGB */
1493
1494 /* For indexed PNG data (PNG_COLOR_TYPE_PALETTE) many of the transformations
1495 * can be performed directly on the palette, and some (such as rgb to gray)
1496 * can be optimized inside the palette. This is particularly true of the
1497 * composite (background and alpha) stuff, which can be pretty much all done
1498 * in the palette even if the result is expanded to RGB or gray afterward.
1499 *
1500 * NOTE: this is Not Yet Implemented, the code behaves as in 1.5.1 and
1501 * earlier and the palette stuff is actually handled on the first row. This
1502 * leads to the reported bug that the palette returned by png_get_PLTE is not
1503 * updated.
1504 */
1505 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1506 png_init_palette_transformations(png_ptr);
1507
1508 else
1509 png_init_rgb_transformations(png_ptr);
1510
1511 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1512 defined(PNG_READ_EXPAND_16_SUPPORTED)
1513 if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
1514 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
1515 (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
1516 png_ptr->bit_depth != 16)
1517 {
1518 /* TODO: fix this. Because the expand_16 operation is after the compose
1519 * handling the background color must be 8, not 16, bits deep, but the
1520 * application will supply a 16-bit value so reduce it here.
1521 *
1522 * The PNG_BACKGROUND_EXPAND code above does not expand to 16 bits at
1523 * present, so that case is ok (until do_expand_16 is moved.)
1524 *
1525 * NOTE: this discards the low 16 bits of the user supplied background
1526 * color, but until expand_16 works properly there is no choice!
1527 */
1528 # define CHOP(x) (x)=((png_uint_16)PNG_DIV257(x))
1529 CHOP(png_ptr->background.red);
1530 CHOP(png_ptr->background.green);
1531 CHOP(png_ptr->background.blue);
1532 CHOP(png_ptr->background.gray);
1533 # undef CHOP
1534 }
1535 #endif /* READ_BACKGROUND && READ_EXPAND_16 */
1536
1537 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1538 (defined(PNG_READ_SCALE_16_TO_8_SUPPORTED) || \
1539 defined(PNG_READ_STRIP_16_TO_8_SUPPORTED))
1540 if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) != 0 &&
1541 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
1542 (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
1543 png_ptr->bit_depth == 16)
1544 {
1545 /* On the other hand, if a 16-bit file is to be reduced to 8-bits per
1546 * component this will also happen after PNG_COMPOSE and so the background
1547 * color must be pre-expanded here.
1548 *
1549 * TODO: fix this too.
1550 */
1551 png_ptr->background.red = (png_uint_16)(png_ptr->background.red * 257);
1552 png_ptr->background.green =
1553 (png_uint_16)(png_ptr->background.green * 257);
1554 png_ptr->background.blue = (png_uint_16)(png_ptr->background.blue * 257);
1555 png_ptr->background.gray = (png_uint_16)(png_ptr->background.gray * 257);
1556 }
1557 #endif
1558
1559 /* NOTE: below 'PNG_READ_ALPHA_MODE_SUPPORTED' is presumed to also enable the
1560 * background support (see the comments in scripts/pnglibconf.dfa), this
1561 * allows pre-multiplication of the alpha channel to be implemented as
1562 * compositing on black. This is probably sub-optimal and has been done in
1563 * 1.5.4 betas simply to enable external critique and testing (i.e. to
1564 * implement the new API quickly, without lots of internal changes.)
1565 */
1566
1567 #ifdef PNG_READ_GAMMA_SUPPORTED
1568 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1569 /* Includes ALPHA_MODE */
1570 png_ptr->background_1 = png_ptr->background;
1571 # endif
1572
1573 /* This needs to change - in the palette image case a whole set of tables are
1574 * built when it would be quicker to just calculate the correct value for
1575 * each palette entry directly. Also, the test is too tricky - why check
1576 * PNG_RGB_TO_GRAY if PNG_GAMMA is not set? The answer seems to be that
1577 * PNG_GAMMA is cancelled even if the gamma is known? The test excludes the
1578 * PNG_COMPOSE case, so apparently if there is no *overall* gamma correction
1579 * the gamma tables will not be built even if composition is required on a
1580 * gamma encoded value.
1581 *
1582 * In 1.5.4 this is addressed below by an additional check on the individual
1583 * file gamma - if it is not 1.0 both RGB_TO_GRAY and COMPOSE need the
1584 * tables.
1585 */
1586 if ((png_ptr->transformations & PNG_GAMMA) != 0 ||
1587 ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0 &&
1588 (png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
1589 png_gamma_significant(png_ptr->screen_gamma) != 0)) ||
1590 ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
1591 (png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
1592 png_gamma_significant(png_ptr->screen_gamma) != 0
1593 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1594 || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE &&
1595 png_gamma_significant(png_ptr->background_gamma) != 0)
1596 # endif
1597 )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 &&
1598 png_gamma_significant(png_ptr->screen_gamma) != 0))
1599 {
1600 png_build_gamma_table(png_ptr, png_ptr->bit_depth);
1601
1602 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1603 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1604 {
1605 /* Issue a warning about this combination: because RGB_TO_GRAY is
1606 * optimized to do the gamma transform if present yet do_background has
1607 * to do the same thing if both options are set a
1608 * double-gamma-correction happens. This is true in all versions of
1609 * libpng to date.
1610 */
1611 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
1612 png_warning(png_ptr,
1613 "libpng does not support gamma+background+rgb_to_gray");
1614
1615 if ((png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) != 0)
1616 {
1617 /* We don't get to here unless there is a tRNS chunk with non-opaque
1618 * entries - see the checking code at the start of this function.
1619 */
1620 png_color back, back_1;
1621 png_colorp palette = png_ptr->palette;
1622 int num_palette = png_ptr->num_palette;
1623 int i;
1624 if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_FILE)
1625 {
1626
1627 back.red = png_ptr->gamma_table[png_ptr->background.red];
1628 back.green = png_ptr->gamma_table[png_ptr->background.green];
1629 back.blue = png_ptr->gamma_table[png_ptr->background.blue];
1630
1631 back_1.red = png_ptr->gamma_to_1[png_ptr->background.red];
1632 back_1.green = png_ptr->gamma_to_1[png_ptr->background.green];
1633 back_1.blue = png_ptr->gamma_to_1[png_ptr->background.blue];
1634 }
1635 else
1636 {
1637 png_fixed_point g, gs;
1638
1639 switch (png_ptr->background_gamma_type)
1640 {
1641 case PNG_BACKGROUND_GAMMA_SCREEN:
1642 g = (png_ptr->screen_gamma);
1643 gs = PNG_FP_1;
1644 break;
1645
1646 case PNG_BACKGROUND_GAMMA_FILE:
1647 g = png_reciprocal(png_ptr->colorspace.gamma);
1648 gs = png_reciprocal2(png_ptr->colorspace.gamma,
1649 png_ptr->screen_gamma);
1650 break;
1651
1652 case PNG_BACKGROUND_GAMMA_UNIQUE:
1653 g = png_reciprocal(png_ptr->background_gamma);
1654 gs = png_reciprocal2(png_ptr->background_gamma,
1655 png_ptr->screen_gamma);
1656 break;
1657 default:
1658 g = PNG_FP_1; /* back_1 */
1659 gs = PNG_FP_1; /* back */
1660 break;
1661 }
1662
1663 if (png_gamma_significant(gs) != 0)
1664 {
1665 back.red = png_gamma_8bit_correct(png_ptr->background.red,
1666 gs);
1667 back.green = png_gamma_8bit_correct(png_ptr->background.green,
1668 gs);
1669 back.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1670 gs);
1671 }
1672
1673 else
1674 {
1675 back.red = (png_byte)png_ptr->background.red;
1676 back.green = (png_byte)png_ptr->background.green;
1677 back.blue = (png_byte)png_ptr->background.blue;
1678 }
1679
1680 if (png_gamma_significant(g) != 0)
1681 {
1682 back_1.red = png_gamma_8bit_correct(png_ptr->background.red,
1683 g);
1684 back_1.green = png_gamma_8bit_correct(
1685 png_ptr->background.green, g);
1686 back_1.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1687 g);
1688 }
1689
1690 else
1691 {
1692 back_1.red = (png_byte)png_ptr->background.red;
1693 back_1.green = (png_byte)png_ptr->background.green;
1694 back_1.blue = (png_byte)png_ptr->background.blue;
1695 }
1696 }
1697
1698 for (i = 0; i < num_palette; i++)
1699 {
1700 if (i < (int)png_ptr->num_trans &&
1701 png_ptr->trans_alpha[i] != 0xff)
1702 {
1703 if (png_ptr->trans_alpha[i] == 0)
1704 {
1705 palette[i] = back;
1706 }
1707 else /* if (png_ptr->trans_alpha[i] != 0xff) */
1708 {
1709 png_byte v, w;
1710
1711 v = png_ptr->gamma_to_1[palette[i].red];
1712 png_composite(w, v, png_ptr->trans_alpha[i], back_1.red);
1713 palette[i].red = png_ptr->gamma_from_1[w];
1714
1715 v = png_ptr->gamma_to_1[palette[i].green];
1716 png_composite(w, v, png_ptr->trans_alpha[i], back_1.green);
1717 palette[i].green = png_ptr->gamma_from_1[w];
1718
1719 v = png_ptr->gamma_to_1[palette[i].blue];
1720 png_composite(w, v, png_ptr->trans_alpha[i], back_1.blue);
1721 palette[i].blue = png_ptr->gamma_from_1[w];
1722 }
1723 }
1724 else
1725 {
1726 palette[i].red = png_ptr->gamma_table[palette[i].red];
1727 palette[i].green = png_ptr->gamma_table[palette[i].green];
1728 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1729 }
1730 }
1731
1732 /* Prevent the transformations being done again.
1733 *
1734 * NOTE: this is highly dubious; it removes the transformations in
1735 * place. This seems inconsistent with the general treatment of the
1736 * transformations elsewhere.
1737 */
1738 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_GAMMA);
1739 } /* color_type == PNG_COLOR_TYPE_PALETTE */
1740
1741 /* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */
1742 else /* color_type != PNG_COLOR_TYPE_PALETTE */
1743 {
1744 int gs_sig, g_sig;
1745 png_fixed_point g = PNG_FP_1; /* Correction to linear */
1746 png_fixed_point gs = PNG_FP_1; /* Correction to screen */
1747
1748 switch (png_ptr->background_gamma_type)
1749 {
1750 case PNG_BACKGROUND_GAMMA_SCREEN:
1751 g = png_ptr->screen_gamma;
1752 /* gs = PNG_FP_1; */
1753 break;
1754
1755 case PNG_BACKGROUND_GAMMA_FILE:
1756 g = png_reciprocal(png_ptr->colorspace.gamma);
1757 gs = png_reciprocal2(png_ptr->colorspace.gamma,
1758 png_ptr->screen_gamma);
1759 break;
1760
1761 case PNG_BACKGROUND_GAMMA_UNIQUE:
1762 g = png_reciprocal(png_ptr->background_gamma);
1763 gs = png_reciprocal2(png_ptr->background_gamma,
1764 png_ptr->screen_gamma);
1765 break;
1766
1767 default:
1768 png_error(png_ptr, "invalid background gamma type");
1769 }
1770
1771 g_sig = png_gamma_significant(g);
1772 gs_sig = png_gamma_significant(gs);
1773
1774 if (g_sig != 0)
1775 png_ptr->background_1.gray = png_gamma_correct(png_ptr,
1776 png_ptr->background.gray, g);
1777
1778 if (gs_sig != 0)
1779 png_ptr->background.gray = png_gamma_correct(png_ptr,
1780 png_ptr->background.gray, gs);
1781
1782 if ((png_ptr->background.red != png_ptr->background.green) ||
1783 (png_ptr->background.red != png_ptr->background.blue) ||
1784 (png_ptr->background.red != png_ptr->background.gray))
1785 {
1786 /* RGB or RGBA with color background */
1787 if (g_sig != 0)
1788 {
1789 png_ptr->background_1.red = png_gamma_correct(png_ptr,
1790 png_ptr->background.red, g);
1791
1792 png_ptr->background_1.green = png_gamma_correct(png_ptr,
1793 png_ptr->background.green, g);
1794
1795 png_ptr->background_1.blue = png_gamma_correct(png_ptr,
1796 png_ptr->background.blue, g);
1797 }
1798
1799 if (gs_sig != 0)
1800 {
1801 png_ptr->background.red = png_gamma_correct(png_ptr,
1802 png_ptr->background.red, gs);
1803
1804 png_ptr->background.green = png_gamma_correct(png_ptr,
1805 png_ptr->background.green, gs);
1806
1807 png_ptr->background.blue = png_gamma_correct(png_ptr,
1808 png_ptr->background.blue, gs);
1809 }
1810 }
1811
1812 else
1813 {
1814 /* GRAY, GRAY ALPHA, RGB, or RGBA with gray background */
1815 png_ptr->background_1.red = png_ptr->background_1.green
1816 = png_ptr->background_1.blue = png_ptr->background_1.gray;
1817
1818 png_ptr->background.red = png_ptr->background.green
1819 = png_ptr->background.blue = png_ptr->background.gray;
1820 }
1821
1822 /* The background is now in screen gamma: */
1823 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_SCREEN;
1824 } /* color_type != PNG_COLOR_TYPE_PALETTE */
1825 }/* png_ptr->transformations & PNG_BACKGROUND */
1826
1827 else
1828 /* Transformation does not include PNG_BACKGROUND */
1829 #endif /* READ_BACKGROUND */
1830 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE
1831 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1832 /* RGB_TO_GRAY needs to have non-gamma-corrected values! */
1833 && ((png_ptr->transformations & PNG_EXPAND) == 0 ||
1834 (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
1835 #endif
1836 )
1837 {
1838 png_colorp palette = png_ptr->palette;
1839 int num_palette = png_ptr->num_palette;
1840 int i;
1841
1842 /* NOTE: there are other transformations that should probably be in
1843 * here too.
1844 */
1845 for (i = 0; i < num_palette; i++)
1846 {
1847 palette[i].red = png_ptr->gamma_table[palette[i].red];
1848 palette[i].green = png_ptr->gamma_table[palette[i].green];
1849 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1850 }
1851
1852 /* Done the gamma correction. */
1853 png_ptr->transformations &= ~PNG_GAMMA;
1854 } /* color_type == PALETTE && !PNG_BACKGROUND transformation */
1855 }
1856 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1857 else
1858 #endif
1859 #endif /* READ_GAMMA */
1860
1861 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1862 /* No GAMMA transformation (see the hanging else 4 lines above) */
1863 if ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
1864 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1865 {
1866 int i;
1867 int istop = (int)png_ptr->num_trans;
1868 png_color back;
1869 png_colorp palette = png_ptr->palette;
1870
1871 back.red = (png_byte)png_ptr->background.red;
1872 back.green = (png_byte)png_ptr->background.green;
1873 back.blue = (png_byte)png_ptr->background.blue;
1874
1875 for (i = 0; i < istop; i++)
1876 {
1877 if (png_ptr->trans_alpha[i] == 0)
1878 {
1879 palette[i] = back;
1880 }
1881
1882 else if (png_ptr->trans_alpha[i] != 0xff)
1883 {
1884 /* The png_composite() macro is defined in png.h */
1885 png_composite(palette[i].red, palette[i].red,
1886 png_ptr->trans_alpha[i], back.red);
1887
1888 png_composite(palette[i].green, palette[i].green,
1889 png_ptr->trans_alpha[i], back.green);
1890
1891 png_composite(palette[i].blue, palette[i].blue,
1892 png_ptr->trans_alpha[i], back.blue);
1893 }
1894 }
1895
1896 png_ptr->transformations &= ~PNG_COMPOSE;
1897 }
1898 #endif /* READ_BACKGROUND */
1899
1900 #ifdef PNG_READ_SHIFT_SUPPORTED
1901 if ((png_ptr->transformations & PNG_SHIFT) != 0 &&
1902 (png_ptr->transformations & PNG_EXPAND) == 0 &&
1903 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1904 {
1905 int i;
1906 int istop = png_ptr->num_palette;
1907 int shift = 8 - png_ptr->sig_bit.red;
1908
1909 png_ptr->transformations &= ~PNG_SHIFT;
1910
1911 /* significant bits can be in the range 1 to 7 for a meaninful result, if
1912 * the number of significant bits is 0 then no shift is done (this is an
1913 * error condition which is silently ignored.)
1914 */
1915 if (shift > 0 && shift < 8)
1916 for (i=0; i<istop; ++i)
1917 {
1918 int component = png_ptr->palette[i].red;
1919
1920 component >>= shift;
1921 png_ptr->palette[i].red = (png_byte)component;
1922 }
1923
1924 shift = 8 - png_ptr->sig_bit.green;
1925 if (shift > 0 && shift < 8)
1926 for (i=0; i<istop; ++i)
1927 {
1928 int component = png_ptr->palette[i].green;
1929
1930 component >>= shift;
1931 png_ptr->palette[i].green = (png_byte)component;
1932 }
1933
1934 shift = 8 - png_ptr->sig_bit.blue;
1935 if (shift > 0 && shift < 8)
1936 for (i=0; i<istop; ++i)
1937 {
1938 int component = png_ptr->palette[i].blue;
1939
1940 component >>= shift;
1941 png_ptr->palette[i].blue = (png_byte)component;
1942 }
1943 }
1944 #endif /* READ_SHIFT */
1945 }
1946
1947 /* Modify the info structure to reflect the transformations. The
1948 * info should be updated so a PNG file could be written with it,
1949 * assuming the transformations result in valid PNG data.
1950 */
1951 void /* PRIVATE */
1952 png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
1953 {
1954 png_debug(1, "in png_read_transform_info");
1955
1956 #ifdef PNG_READ_EXPAND_SUPPORTED
1957 if ((png_ptr->transformations & PNG_EXPAND) != 0)
1958 {
1959 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1960 {
1961 /* This check must match what actually happens in
1962 * png_do_expand_palette; if it ever checks the tRNS chunk to see if
1963 * it is all opaque we must do the same (at present it does not.)
1964 */
1965 if (png_ptr->num_trans > 0)
1966 info_ptr->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
1967
1968 else
1969 info_ptr->color_type = PNG_COLOR_TYPE_RGB;
1970
1971 info_ptr->bit_depth = 8;
1972 info_ptr->num_trans = 0;
1973
1974 if (png_ptr->palette == NULL)
1975 png_error (png_ptr, "Palette is NULL in indexed image");
1976 }
1977 else
1978 {
1979 if (png_ptr->num_trans != 0)
1980 {
1981 if ((png_ptr->transformations & PNG_EXPAND_tRNS) != 0)
1982 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
1983 }
1984 if (info_ptr->bit_depth < 8)
1985 info_ptr->bit_depth = 8;
1986
1987 info_ptr->num_trans = 0;
1988 }
1989 }
1990 #endif
1991
1992 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
1993 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
1994 /* The following is almost certainly wrong unless the background value is in
1995 * the screen space!
1996 */
1997 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1998 info_ptr->background = png_ptr->background;
1999 #endif
2000
2001 #ifdef PNG_READ_GAMMA_SUPPORTED
2002 /* The following used to be conditional on PNG_GAMMA (prior to 1.5.4),
2003 * however it seems that the code in png_init_read_transformations, which has
2004 * been called before this from png_read_update_info->png_read_start_row
2005 * sometimes does the gamma transform and cancels the flag.
2006 *
2007 * TODO: this looks wrong; the info_ptr should end up with a gamma equal to
2008 * the screen_gamma value. The following probably results in weirdness if
2009 * the info_ptr is used by the app after the rows have been read.
2010 */
2011 info_ptr->colorspace.gamma = png_ptr->colorspace.gamma;
2012 #endif
2013
2014 if (info_ptr->bit_depth == 16)
2015 {
2016 # ifdef PNG_READ_16BIT_SUPPORTED
2017 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2018 if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0)
2019 info_ptr->bit_depth = 8;
2020 # endif
2021
2022 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2023 if ((png_ptr->transformations & PNG_16_TO_8) != 0)
2024 info_ptr->bit_depth = 8;
2025 # endif
2026
2027 # else
2028 /* No 16 bit support: force chopping 16-bit input down to 8, in this case
2029 * the app program can chose if both APIs are available by setting the
2030 * correct scaling to use.
2031 */
2032 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2033 /* For compatibility with previous versions use the strip method by
2034 * default. This code works because if PNG_SCALE_16_TO_8 is already
2035 * set the code below will do that in preference to the chop.
2036 */
2037 png_ptr->transformations |= PNG_16_TO_8;
2038 info_ptr->bit_depth = 8;
2039 # else
2040
2041 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2042 png_ptr->transformations |= PNG_SCALE_16_TO_8;
2043 info_ptr->bit_depth = 8;
2044 # else
2045
2046 CONFIGURATION ERROR: you must enable at least one 16 to 8 method
2047 # endif
2048 # endif
2049 #endif /* !READ_16BIT */
2050 }
2051
2052 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2053 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
2054 info_ptr->color_type = (png_byte)(info_ptr->color_type |
2055 PNG_COLOR_MASK_COLOR);
2056 #endif
2057
2058 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2059 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
2060 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2061 ~PNG_COLOR_MASK_COLOR);
2062 #endif
2063
2064 #ifdef PNG_READ_QUANTIZE_SUPPORTED
2065 if ((png_ptr->transformations & PNG_QUANTIZE) != 0)
2066 {
2067 if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
2068 (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) &&
2069 png_ptr->palette_lookup != 0 && info_ptr->bit_depth == 8)
2070 {
2071 info_ptr->color_type = PNG_COLOR_TYPE_PALETTE;
2072 }
2073 }
2074 #endif
2075
2076 #ifdef PNG_READ_EXPAND_16_SUPPORTED
2077 if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
2078 info_ptr->bit_depth == 8 &&
2079 info_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
2080 {
2081 info_ptr->bit_depth = 16;
2082 }
2083 #endif
2084
2085 #ifdef PNG_READ_PACK_SUPPORTED
2086 if ((png_ptr->transformations & PNG_PACK) != 0 &&
2087 (info_ptr->bit_depth < 8))
2088 info_ptr->bit_depth = 8;
2089 #endif
2090
2091 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
2092 info_ptr->channels = 1;
2093
2094 else if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
2095 info_ptr->channels = 3;
2096
2097 else
2098 info_ptr->channels = 1;
2099
2100 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
2101 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0)
2102 {
2103 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2104 ~PNG_COLOR_MASK_ALPHA);
2105 info_ptr->num_trans = 0;
2106 }
2107 #endif
2108
2109 if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
2110 info_ptr->channels++;
2111
2112 #ifdef PNG_READ_FILLER_SUPPORTED
2113 /* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */
2114 if ((png_ptr->transformations & PNG_FILLER) != 0 &&
2115 (info_ptr->color_type == PNG_COLOR_TYPE_RGB ||
2116 info_ptr->color_type == PNG_COLOR_TYPE_GRAY))
2117 {
2118 info_ptr->channels++;
2119 /* If adding a true alpha channel not just filler */
2120 if ((png_ptr->transformations & PNG_ADD_ALPHA) != 0)
2121 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
2122 }
2123 #endif
2124
2125 #if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \
2126 defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
2127 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
2128 {
2129 if (info_ptr->bit_depth < png_ptr->user_transform_depth)
2130 info_ptr->bit_depth = png_ptr->user_transform_depth;
2131
2132 if (info_ptr->channels < png_ptr->user_transform_channels)
2133 info_ptr->channels = png_ptr->user_transform_channels;
2134 }
2135 #endif
2136
2137 info_ptr->pixel_depth = (png_byte)(info_ptr->channels *
2138 info_ptr->bit_depth);
2139
2140 info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, info_ptr->width);
2141
2142 /* Adding in 1.5.4: cache the above value in png_struct so that we can later
2143 * check in png_rowbytes that the user buffer won't get overwritten. Note
2144 * that the field is not always set - if png_read_update_info isn't called
2145 * the application has to either not do any transforms or get the calculation
2146 * right itself.
2147 */
2148 png_ptr->info_rowbytes = info_ptr->rowbytes;
2149
2150 #ifndef PNG_READ_EXPAND_SUPPORTED
2151 if (png_ptr != NULL)
2152 return;
2153 #endif
2154 }
2155
2156 #ifdef PNG_READ_PACK_SUPPORTED
2157 /* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
2158 * without changing the actual values. Thus, if you had a row with
2159 * a bit depth of 1, you would end up with bytes that only contained
2160 * the numbers 0 or 1. If you would rather they contain 0 and 255, use
2161 * png_do_shift() after this.
2162 */
2163 static void
2164 png_do_unpack(png_row_infop row_info, png_bytep row)
2165 {
2166 png_debug(1, "in png_do_unpack");
2167
2168 if (row_info->bit_depth < 8)
2169 {
2170 png_uint_32 i;
2171 png_uint_32 row_width=row_info->width;
2172
2173 switch (row_info->bit_depth)
2174 {
2175 case 1:
2176 {
2177 png_bytep sp = row + (png_size_t)((row_width - 1) >> 3);
2178 png_bytep dp = row + (png_size_t)row_width - 1;
2179 png_uint_32 shift = 7 - (int)((row_width + 7) & 0x07);
2180 for (i = 0; i < row_width; i++)
2181 {
2182 *dp = (png_byte)((*sp >> shift) & 0x01);
2183
2184 if (shift == 7)
2185 {
2186 shift = 0;
2187 sp--;
2188 }
2189
2190 else
2191 shift++;
2192
2193 dp--;
2194 }
2195 break;
2196 }
2197
2198 case 2:
2199 {
2200
2201 png_bytep sp = row + (png_size_t)((row_width - 1) >> 2);
2202 png_bytep dp = row + (png_size_t)row_width - 1;
2203 png_uint_32 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
2204 for (i = 0; i < row_width; i++)
2205 {
2206 *dp = (png_byte)((*sp >> shift) & 0x03);
2207
2208 if (shift == 6)
2209 {
2210 shift = 0;
2211 sp--;
2212 }
2213
2214 else
2215 shift += 2;
2216
2217 dp--;
2218 }
2219 break;
2220 }
2221
2222 case 4:
2223 {
2224 png_bytep sp = row + (png_size_t)((row_width - 1) >> 1);
2225 png_bytep dp = row + (png_size_t)row_width - 1;
2226 png_uint_32 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
2227 for (i = 0; i < row_width; i++)
2228 {
2229 *dp = (png_byte)((*sp >> shift) & 0x0f);
2230
2231 if (shift == 4)
2232 {
2233 shift = 0;
2234 sp--;
2235 }
2236
2237 else
2238 shift = 4;
2239
2240 dp--;
2241 }
2242 break;
2243 }
2244
2245 default:
2246 break;
2247 }
2248 row_info->bit_depth = 8;
2249 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2250 row_info->rowbytes = row_width * row_info->channels;
2251 }
2252 }
2253 #endif
2254
2255 #ifdef PNG_READ_SHIFT_SUPPORTED
2256 /* Reverse the effects of png_do_shift. This routine merely shifts the
2257 * pixels back to their significant bits values. Thus, if you have
2258 * a row of bit depth 8, but only 5 are significant, this will shift
2259 * the values back to 0 through 31.
2260 */
2261 static void
2262 png_do_unshift(png_row_infop row_info, png_bytep row,
2263 png_const_color_8p sig_bits)
2264 {
2265 int color_type;
2266
2267 png_debug(1, "in png_do_unshift");
2268
2269 /* The palette case has already been handled in the _init routine. */
2270 color_type = row_info->color_type;
2271
2272 if (color_type != PNG_COLOR_TYPE_PALETTE)
2273 {
2274 int shift[4];
2275 int channels = 0;
2276 int bit_depth = row_info->bit_depth;
2277
2278 if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
2279 {
2280 shift[channels++] = bit_depth - sig_bits->red;
2281 shift[channels++] = bit_depth - sig_bits->green;
2282 shift[channels++] = bit_depth - sig_bits->blue;
2283 }
2284
2285 else
2286 {
2287 shift[channels++] = bit_depth - sig_bits->gray;
2288 }
2289
2290 if ((color_type & PNG_COLOR_MASK_ALPHA) != 0)
2291 {
2292 shift[channels++] = bit_depth - sig_bits->alpha;
2293 }
2294
2295 {
2296 int c, have_shift;
2297
2298 for (c = have_shift = 0; c < channels; ++c)
2299 {
2300 /* A shift of more than the bit depth is an error condition but it
2301 * gets ignored here.
2302 */
2303 if (shift[c] <= 0 || shift[c] >= bit_depth)
2304 shift[c] = 0;
2305
2306 else
2307 have_shift = 1;
2308 }
2309
2310 if (have_shift == 0)
2311 return;
2312 }
2313
2314 switch (bit_depth)
2315 {
2316 default:
2317 /* Must be 1bpp gray: should not be here! */
2318 /* NOTREACHED */
2319 break;
2320
2321 case 2:
2322 /* Must be 2bpp gray */
2323 /* assert(channels == 1 && shift[0] == 1) */
2324 {
2325 png_bytep bp = row;
2326 png_bytep bp_end = bp + row_info->rowbytes;
2327
2328 while (bp < bp_end)
2329 {
2330 int b = (*bp >> 1) & 0x55;
2331 *bp++ = (png_byte)b;
2332 }
2333 break;
2334 }
2335
2336 case 4:
2337 /* Must be 4bpp gray */
2338 /* assert(channels == 1) */
2339 {
2340 png_bytep bp = row;
2341 png_bytep bp_end = bp + row_info->rowbytes;
2342 int gray_shift = shift[0];
2343 int mask = 0xf >> gray_shift;
2344
2345 mask |= mask << 4;
2346
2347 while (bp < bp_end)
2348 {
2349 int b = (*bp >> gray_shift) & mask;
2350 *bp++ = (png_byte)b;
2351 }
2352 break;
2353 }
2354
2355 case 8:
2356 /* Single byte components, G, GA, RGB, RGBA */
2357 {
2358 png_bytep bp = row;
2359 png_bytep bp_end = bp + row_info->rowbytes;
2360 int channel = 0;
2361
2362 while (bp < bp_end)
2363 {
2364 int b = *bp >> shift[channel];
2365 if (++channel >= channels)
2366 channel = 0;
2367 *bp++ = (png_byte)b;
2368 }
2369 break;
2370 }
2371
2372 #ifdef PNG_READ_16BIT_SUPPORTED
2373 case 16:
2374 /* Double byte components, G, GA, RGB, RGBA */
2375 {
2376 png_bytep bp = row;
2377 png_bytep bp_end = bp + row_info->rowbytes;
2378 int channel = 0;
2379
2380 while (bp < bp_end)
2381 {
2382 int value = (bp[0] << 8) + bp[1];
2383
2384 value >>= shift[channel];
2385 if (++channel >= channels)
2386 channel = 0;
2387 *bp++ = (png_byte)(value >> 8);
2388 *bp++ = (png_byte)(value & 0xff);
2389 }
2390 break;
2391 }
2392 #endif
2393 }
2394 }
2395 }
2396 #endif
2397
2398 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2399 /* Scale rows of bit depth 16 down to 8 accurately */
2400 static void
2401 png_do_scale_16_to_8(png_row_infop row_info, png_bytep row)
2402 {
2403 png_debug(1, "in png_do_scale_16_to_8");
2404
2405 if (row_info->bit_depth == 16)
2406 {
2407 png_bytep sp = row; /* source */
2408 png_bytep dp = row; /* destination */
2409 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2410
2411 while (sp < ep)
2412 {
2413 /* The input is an array of 16 bit components, these must be scaled to
2414 * 8 bits each. For a 16 bit value V the required value (from the PNG
2415 * specification) is:
2416 *
2417 * (V * 255) / 65535
2418 *
2419 * This reduces to round(V / 257), or floor((V + 128.5)/257)
2420 *
2421 * Represent V as the two byte value vhi.vlo. Make a guess that the
2422 * result is the top byte of V, vhi, then the correction to this value
2423 * is:
2424 *
2425 * error = floor(((V-vhi.vhi) + 128.5) / 257)
2426 * = floor(((vlo-vhi) + 128.5) / 257)
2427 *
2428 * This can be approximated using integer arithmetic (and a signed
2429 * shift):
2430 *
2431 * error = (vlo-vhi+128) >> 8;
2432 *
2433 * The approximate differs from the exact answer only when (vlo-vhi) is
2434 * 128; it then gives a correction of +1 when the exact correction is
2435 * 0. This gives 128 errors. The exact answer (correct for all 16 bit
2436 * input values) is:
2437 *
2438 * error = (vlo-vhi+128)*65535 >> 24;
2439 *
2440 * An alternative arithmetic calculation which also gives no errors is:
2441 *
2442 * (V * 255 + 32895) >> 16
2443 */
2444
2445 png_int_32 tmp = *sp++; /* must be signed! */
2446 tmp += (((int)*sp++ - tmp + 128) * 65535) >> 24;
2447 *dp++ = (png_byte)tmp;
2448 }
2449
2450 row_info->bit_depth = 8;
2451 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2452 row_info->rowbytes = row_info->width * row_info->channels;
2453 }
2454 }
2455 #endif
2456
2457 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2458 static void
2459 /* Simply discard the low byte. This was the default behavior prior
2460 * to libpng-1.5.4.
2461 */
2462 png_do_chop(png_row_infop row_info, png_bytep row)
2463 {
2464 png_debug(1, "in png_do_chop");
2465
2466 if (row_info->bit_depth == 16)
2467 {
2468 png_bytep sp = row; /* source */
2469 png_bytep dp = row; /* destination */
2470 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2471
2472 while (sp < ep)
2473 {
2474 *dp++ = *sp;
2475 sp += 2; /* skip low byte */
2476 }
2477
2478 row_info->bit_depth = 8;
2479 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2480 row_info->rowbytes = row_info->width * row_info->channels;
2481 }
2482 }
2483 #endif
2484
2485 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
2486 static void
2487 png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
2488 {
2489 png_debug(1, "in png_do_read_swap_alpha");
2490
2491 {
2492 png_uint_32 row_width = row_info->width;
2493 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2494 {
2495 /* This converts from RGBA to ARGB */
2496 if (row_info->bit_depth == 8)
2497 {
2498 png_bytep sp = row + row_info->rowbytes;
2499 png_bytep dp = sp;
2500 png_byte save;
2501 png_uint_32 i;
2502
2503 for (i = 0; i < row_width; i++)
2504 {
2505 save = *(--sp);
2506 *(--dp) = *(--sp);
2507 *(--dp) = *(--sp);
2508 *(--dp) = *(--sp);
2509 *(--dp) = save;
2510 }
2511 }
2512
2513 #ifdef PNG_READ_16BIT_SUPPORTED
2514 /* This converts from RRGGBBAA to AARRGGBB */
2515 else
2516 {
2517 png_bytep sp = row + row_info->rowbytes;
2518 png_bytep dp = sp;
2519 png_byte save[2];
2520 png_uint_32 i;
2521
2522 for (i = 0; i < row_width; i++)
2523 {
2524 save[0] = *(--sp);
2525 save[1] = *(--sp);
2526 *(--dp) = *(--sp);
2527 *(--dp) = *(--sp);
2528 *(--dp) = *(--sp);
2529 *(--dp) = *(--sp);
2530 *(--dp) = *(--sp);
2531 *(--dp) = *(--sp);
2532 *(--dp) = save[0];
2533 *(--dp) = save[1];
2534 }
2535 }
2536 #endif
2537 }
2538
2539 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2540 {
2541 /* This converts from GA to AG */
2542 if (row_info->bit_depth == 8)
2543 {
2544 png_bytep sp = row + row_info->rowbytes;
2545 png_bytep dp = sp;
2546 png_byte save;
2547 png_uint_32 i;
2548
2549 for (i = 0; i < row_width; i++)
2550 {
2551 save = *(--sp);
2552 *(--dp) = *(--sp);
2553 *(--dp) = save;
2554 }
2555 }
2556
2557 #ifdef PNG_READ_16BIT_SUPPORTED
2558 /* This converts from GGAA to AAGG */
2559 else
2560 {
2561 png_bytep sp = row + row_info->rowbytes;
2562 png_bytep dp = sp;
2563 png_byte save[2];
2564 png_uint_32 i;
2565
2566 for (i = 0; i < row_width; i++)
2567 {
2568 save[0] = *(--sp);
2569 save[1] = *(--sp);
2570 *(--dp) = *(--sp);
2571 *(--dp) = *(--sp);
2572 *(--dp) = save[0];
2573 *(--dp) = save[1];
2574 }
2575 }
2576 #endif
2577 }
2578 }
2579 }
2580 #endif
2581
2582 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
2583 static void
2584 png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
2585 {
2586 png_uint_32 row_width;
2587 png_debug(1, "in png_do_read_invert_alpha");
2588
2589 row_width = row_info->width;
2590 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2591 {
2592 if (row_info->bit_depth == 8)
2593 {
2594 /* This inverts the alpha channel in RGBA */
2595 png_bytep sp = row + row_info->rowbytes;
2596 png_bytep dp = sp;
2597 png_uint_32 i;
2598
2599 for (i = 0; i < row_width; i++)
2600 {
2601 *(--dp) = (png_byte)(255 - *(--sp));
2602
2603 /* This does nothing:
2604 *(--dp) = *(--sp);
2605 *(--dp) = *(--sp);
2606 *(--dp) = *(--sp);
2607 We can replace it with:
2608 */
2609 sp-=3;
2610 dp=sp;
2611 }
2612 }
2613
2614 #ifdef PNG_READ_16BIT_SUPPORTED
2615 /* This inverts the alpha channel in RRGGBBAA */
2616 else
2617 {
2618 png_bytep sp = row + row_info->rowbytes;
2619 png_bytep dp = sp;
2620 png_uint_32 i;
2621
2622 for (i = 0; i < row_width; i++)
2623 {
2624 *(--dp) = (png_byte)(255 - *(--sp));
2625 *(--dp) = (png_byte)(255 - *(--sp));
2626
2627 /* This does nothing:
2628 *(--dp) = *(--sp);
2629 *(--dp) = *(--sp);
2630 *(--dp) = *(--sp);
2631 *(--dp) = *(--sp);
2632 *(--dp) = *(--sp);
2633 *(--dp) = *(--sp);
2634 We can replace it with:
2635 */
2636 sp-=6;
2637 dp=sp;
2638 }
2639 }
2640 #endif
2641 }
2642 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2643 {
2644 if (row_info->bit_depth == 8)
2645 {
2646 /* This inverts the alpha channel in GA */
2647 png_bytep sp = row + row_info->rowbytes;
2648 png_bytep dp = sp;
2649 png_uint_32 i;
2650
2651 for (i = 0; i < row_width; i++)
2652 {
2653 *(--dp) = (png_byte)(255 - *(--sp));
2654 *(--dp) = *(--sp);
2655 }
2656 }
2657
2658 #ifdef PNG_READ_16BIT_SUPPORTED
2659 else
2660 {
2661 /* This inverts the alpha channel in GGAA */
2662 png_bytep sp = row + row_info->rowbytes;
2663 png_bytep dp = sp;
2664 png_uint_32 i;
2665
2666 for (i = 0; i < row_width; i++)
2667 {
2668 *(--dp) = (png_byte)(255 - *(--sp));
2669 *(--dp) = (png_byte)(255 - *(--sp));
2670 /*
2671 *(--dp) = *(--sp);
2672 *(--dp) = *(--sp);
2673 */
2674 sp-=2;
2675 dp=sp;
2676 }
2677 }
2678 #endif
2679 }
2680 }
2681 #endif
2682
2683 #ifdef PNG_READ_FILLER_SUPPORTED
2684 /* Add filler channel if we have RGB color */
2685 static void
2686 png_do_read_filler(png_row_infop row_info, png_bytep row,
2687 png_uint_32 filler, png_uint_32 flags)
2688 {
2689 png_uint_32 i;
2690 png_uint_32 row_width = row_info->width;
2691
2692 #ifdef PNG_READ_16BIT_SUPPORTED
2693 png_byte hi_filler = (png_byte)((filler>>8) & 0xff);
2694 #endif
2695 png_byte lo_filler = (png_byte)(filler & 0xff);
2696
2697 png_debug(1, "in png_do_read_filler");
2698
2699 if (
2700 row_info->color_type == PNG_COLOR_TYPE_GRAY)
2701 {
2702 if (row_info->bit_depth == 8)
2703 {
2704 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2705 {
2706 /* This changes the data from G to GX */
2707 png_bytep sp = row + (png_size_t)row_width;
2708 png_bytep dp = sp + (png_size_t)row_width;
2709 for (i = 1; i < row_width; i++)
2710 {
2711 *(--dp) = lo_filler;
2712 *(--dp) = *(--sp);
2713 }
2714 *(--dp) = lo_filler;
2715 row_info->channels = 2;
2716 row_info->pixel_depth = 16;
2717 row_info->rowbytes = row_width * 2;
2718 }
2719
2720 else
2721 {
2722 /* This changes the data from G to XG */
2723 png_bytep sp = row + (png_size_t)row_width;
2724 png_bytep dp = sp + (png_size_t)row_width;
2725 for (i = 0; i < row_width; i++)
2726 {
2727 *(--dp) = *(--sp);
2728 *(--dp) = lo_filler;
2729 }
2730 row_info->channels = 2;
2731 row_info->pixel_depth = 16;
2732 row_info->rowbytes = row_width * 2;
2733 }
2734 }
2735
2736 #ifdef PNG_READ_16BIT_SUPPORTED
2737 else if (row_info->bit_depth == 16)
2738 {
2739 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2740 {
2741 /* This changes the data from GG to GGXX */
2742 png_bytep sp = row + (png_size_t)row_width * 2;
2743 png_bytep dp = sp + (png_size_t)row_width * 2;
2744 for (i = 1; i < row_width; i++)
2745 {
2746 *(--dp) = hi_filler;
2747 *(--dp) = lo_filler;
2748 *(--dp) = *(--sp);
2749 *(--dp) = *(--sp);
2750 }
2751 *(--dp) = hi_filler;
2752 *(--dp) = lo_filler;
2753 row_info->channels = 2;
2754 row_info->pixel_depth = 32;
2755 row_info->rowbytes = row_width * 4;
2756 }
2757
2758 else
2759 {
2760 /* This changes the data from GG to XXGG */
2761 png_bytep sp = row + (png_size_t)row_width * 2;
2762 png_bytep dp = sp + (png_size_t)row_width * 2;
2763 for (i = 0; i < row_width; i++)
2764 {
2765 *(--dp) = *(--sp);
2766 *(--dp) = *(--sp);
2767 *(--dp) = hi_filler;
2768 *(--dp) = lo_filler;
2769 }
2770 row_info->channels = 2;
2771 row_info->pixel_depth = 32;
2772 row_info->rowbytes = row_width * 4;
2773 }
2774 }
2775 #endif
2776 } /* COLOR_TYPE == GRAY */
2777 else if (row_info->color_type == PNG_COLOR_TYPE_RGB)
2778 {
2779 if (row_info->bit_depth == 8)
2780 {
2781 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2782 {
2783 /* This changes the data from RGB to RGBX */
2784 png_bytep sp = row + (png_size_t)row_width * 3;
2785 png_bytep dp = sp + (png_size_t)row_width;
2786 for (i = 1; i < row_width; i++)
2787 {
2788 *(--dp) = lo_filler;
2789 *(--dp) = *(--sp);
2790 *(--dp) = *(--sp);
2791 *(--dp) = *(--sp);
2792 }
2793 *(--dp) = lo_filler;
2794 row_info->channels = 4;
2795 row_info->pixel_depth = 32;
2796 row_info->rowbytes = row_width * 4;
2797 }
2798
2799 else
2800 {
2801 /* This changes the data from RGB to XRGB */
2802 png_bytep sp = row + (png_size_t)row_width * 3;
2803 png_bytep dp = sp + (png_size_t)row_width;
2804 for (i = 0; i < row_width; i++)
2805 {
2806 *(--dp) = *(--sp);
2807 *(--dp) = *(--sp);
2808 *(--dp) = *(--sp);
2809 *(--dp) = lo_filler;
2810 }
2811 row_info->channels = 4;
2812 row_info->pixel_depth = 32;
2813 row_info->rowbytes = row_width * 4;
2814 }
2815 }
2816
2817 #ifdef PNG_READ_16BIT_SUPPORTED
2818 else if (row_info->bit_depth == 16)
2819 {
2820 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2821 {
2822 /* This changes the data from RRGGBB to RRGGBBXX */
2823 png_bytep sp = row + (png_size_t)row_width * 6;
2824 png_bytep dp = sp + (png_size_t)row_width * 2;
2825 for (i = 1; i < row_width; i++)
2826 {
2827 *(--dp) = hi_filler;
2828 *(--dp) = lo_filler;
2829 *(--dp) = *(--sp);
2830 *(--dp) = *(--sp);
2831 *(--dp) = *(--sp);
2832 *(--dp) = *(--sp);
2833 *(--dp) = *(--sp);
2834 *(--dp) = *(--sp);
2835 }
2836 *(--dp) = hi_filler;
2837 *(--dp) = lo_filler;
2838 row_info->channels = 4;
2839 row_info->pixel_depth = 64;
2840 row_info->rowbytes = row_width * 8;
2841 }
2842
2843 else
2844 {
2845 /* This changes the data from RRGGBB to XXRRGGBB */
2846 png_bytep sp = row + (png_size_t)row_width * 6;
2847 png_bytep dp = sp + (png_size_t)row_width * 2;
2848 for (i = 0; i < row_width; i++)
2849 {
2850 *(--dp) = *(--sp);
2851 *(--dp) = *(--sp);
2852 *(--dp) = *(--sp);
2853 *(--dp) = *(--sp);
2854 *(--dp) = *(--sp);
2855 *(--dp) = *(--sp);
2856 *(--dp) = hi_filler;
2857 *(--dp) = lo_filler;
2858 }
2859
2860 row_info->channels = 4;
2861 row_info->pixel_depth = 64;
2862 row_info->rowbytes = row_width * 8;
2863 }
2864 }
2865 #endif
2866 } /* COLOR_TYPE == RGB */
2867 }
2868 #endif
2869
2870 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2871 /* Expand grayscale files to RGB, with or without alpha */
2872 static void
2873 png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
2874 {
2875 png_uint_32 i;
2876 png_uint_32 row_width = row_info->width;
2877
2878 png_debug(1, "in png_do_gray_to_rgb");
2879
2880 if (row_info->bit_depth >= 8 &&
2881 (row_info->color_type & PNG_COLOR_MASK_COLOR) == 0)
2882 {
2883 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
2884 {
2885 if (row_info->bit_depth == 8)
2886 {
2887 /* This changes G to RGB */
2888 png_bytep sp = row + (png_size_t)row_width - 1;
2889 png_bytep dp = sp + (png_size_t)row_width * 2;
2890 for (i = 0; i < row_width; i++)
2891 {
2892 *(dp--) = *sp;
2893 *(dp--) = *sp;
2894 *(dp--) = *(sp--);
2895 }
2896 }
2897
2898 else
2899 {
2900 /* This changes GG to RRGGBB */
2901 png_bytep sp = row + (png_size_t)row_width * 2 - 1;
2902 png_bytep dp = sp + (png_size_t)row_width * 4;
2903 for (i = 0; i < row_width; i++)
2904 {
2905 *(dp--) = *sp;
2906 *(dp--) = *(sp - 1);
2907 *(dp--) = *sp;
2908 *(dp--) = *(sp - 1);
2909 *(dp--) = *(sp--);
2910 *(dp--) = *(sp--);
2911 }
2912 }
2913 }
2914
2915 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2916 {
2917 if (row_info->bit_depth == 8)
2918 {
2919 /* This changes GA to RGBA */
2920 png_bytep sp = row + (png_size_t)row_width * 2 - 1;
2921 png_bytep dp = sp + (png_size_t)row_width * 2;
2922 for (i = 0; i < row_width; i++)
2923 {
2924 *(dp--) = *(sp--);
2925 *(dp--) = *sp;
2926 *(dp--) = *sp;
2927 *(dp--) = *(sp--);
2928 }
2929 }
2930
2931 else
2932 {
2933 /* This changes GGAA to RRGGBBAA */
2934 png_bytep sp = row + (png_size_t)row_width * 4 - 1;
2935 png_bytep dp = sp + (png_size_t)row_width * 4;
2936 for (i = 0; i < row_width; i++)
2937 {
2938 *(dp--) = *(sp--);
2939 *(dp--) = *(sp--);
2940 *(dp--) = *sp;
2941 *(dp--) = *(sp - 1);
2942 *(dp--) = *sp;
2943 *(dp--) = *(sp - 1);
2944 *(dp--) = *(sp--);
2945 *(dp--) = *(sp--);
2946 }
2947 }
2948 }
2949 row_info->channels = (png_byte)(row_info->channels + 2);
2950 row_info->color_type |= PNG_COLOR_MASK_COLOR;
2951 row_info->pixel_depth = (png_byte)(row_info->channels *
2952 row_info->bit_depth);
2953 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
2954 }
2955 }
2956 #endif
2957
2958 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2959 /* Reduce RGB files to grayscale, with or without alpha
2960 * using the equation given in Poynton's ColorFAQ of 1998-01-04 at
2961 * <http://www.inforamp.net/~poynton/> (THIS LINK IS DEAD June 2008 but
2962 * versions dated 1998 through November 2002 have been archived at
2963 * http://web.archive.org/web/20000816232553/http://www.inforamp.net/
2964 * ~poynton/notes/colour_and_gamma/ColorFAQ.txt )
2965 * Charles Poynton poynton at poynton.com
2966 *
2967 * Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
2968 *
2969 * which can be expressed with integers as
2970 *
2971 * Y = (6969 * R + 23434 * G + 2365 * B)/32768
2972 *
2973 * Poynton's current link (as of January 2003 through July 2011):
2974 * <http://www.poynton.com/notes/colour_and_gamma/>
2975 * has changed the numbers slightly:
2976 *
2977 * Y = 0.2126*R + 0.7152*G + 0.0722*B
2978 *
2979 * which can be expressed with integers as
2980 *
2981 * Y = (6966 * R + 23436 * G + 2366 * B)/32768
2982 *
2983 * Historically, however, libpng uses numbers derived from the ITU-R Rec 709
2984 * end point chromaticities and the D65 white point. Depending on the
2985 * precision used for the D65 white point this produces a variety of different
2986 * numbers, however if the four decimal place value used in ITU-R Rec 709 is
2987 * used (0.3127,0.3290) the Y calculation would be:
2988 *
2989 * Y = (6968 * R + 23435 * G + 2366 * B)/32768
2990 *
2991 * While this is correct the rounding results in an overflow for white, because
2992 * the sum of the rounded coefficients is 32769, not 32768. Consequently
2993 * libpng uses, instead, the closest non-overflowing approximation:
2994 *
2995 * Y = (6968 * R + 23434 * G + 2366 * B)/32768
2996 *
2997 * Starting with libpng-1.5.5, if the image being converted has a cHRM chunk
2998 * (including an sRGB chunk) then the chromaticities are used to calculate the
2999 * coefficients. See the chunk handling in pngrutil.c for more information.
3000 *
3001 * In all cases the calculation is to be done in a linear colorspace. If no
3002 * gamma information is available to correct the encoding of the original RGB
3003 * values this results in an implicit assumption that the original PNG RGB
3004 * values were linear.
3005 *
3006 * Other integer coefficents can be used via png_set_rgb_to_gray(). Because
3007 * the API takes just red and green coefficients the blue coefficient is
3008 * calculated to make the sum 32768. This will result in different rounding
3009 * to that used above.
3010 */
3011 static int
3012 png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
3013
3014 {
3015 int rgb_error = 0;
3016
3017 png_debug(1, "in png_do_rgb_to_gray");
3018
3019 if ((row_info->color_type & PNG_COLOR_MASK_PALETTE) == 0 &&
3020 (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
3021 {
3022 PNG_CONST png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff;
3023 PNG_CONST png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff;
3024 PNG_CONST png_uint_32 bc = 32768 - rc - gc;
3025 PNG_CONST png_uint_32 row_width = row_info->width;
3026 PNG_CONST int have_alpha =
3027 (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0;
3028
3029 if (row_info->bit_depth == 8)
3030 {
3031 #ifdef PNG_READ_GAMMA_SUPPORTED
3032 /* Notice that gamma to/from 1 are not necessarily inverses (if
3033 * there is an overall gamma correction). Prior to 1.5.5 this code
3034 * checked the linearized values for equality; this doesn't match
3035 * the documentation, the original values must be checked.
3036 */
3037 if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL)
3038 {
3039 png_bytep sp = row;
3040 png_bytep dp = row;
3041 png_uint_32 i;
3042
3043 for (i = 0; i < row_width; i++)
3044 {
3045 png_byte red = *(sp++);
3046 png_byte green = *(sp++);
3047 png_byte blue = *(sp++);
3048
3049 if (red != green || red != blue)
3050 {
3051 red = png_ptr->gamma_to_1[red];
3052 green = png_ptr->gamma_to_1[green];
3053 blue = png_ptr->gamma_to_1[blue];
3054
3055 rgb_error |= 1;
3056 *(dp++) = png_ptr->gamma_from_1[
3057 (rc*red + gc*green + bc*blue + 16384)>>15];
3058 }
3059
3060 else
3061 {
3062 /* If there is no overall correction the table will not be
3063 * set.
3064 */
3065 if (png_ptr->gamma_table != NULL)
3066 red = png_ptr->gamma_table[red];
3067
3068 *(dp++) = red;
3069 }
3070
3071 if (have_alpha != 0)
3072 *(dp++) = *(sp++);
3073 }
3074 }
3075 else
3076 #endif
3077 {
3078 png_bytep sp = row;
3079 png_bytep dp = row;
3080 png_uint_32 i;
3081
3082 for (i = 0; i < row_width; i++)
3083 {
3084 png_byte red = *(sp++);
3085 png_byte green = *(sp++);
3086 png_byte blue = *(sp++);
3087
3088 if (red != green || red != blue)
3089 {
3090 rgb_error |= 1;
3091 /* NOTE: this is the historical approach which simply
3092 * truncates the results.
3093 */
3094 *(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15);
3095 }
3096
3097 else
3098 *(dp++) = red;
3099
3100 if (have_alpha != 0)
3101 *(dp++) = *(sp++);
3102 }
3103 }
3104 }
3105
3106 else /* RGB bit_depth == 16 */
3107 {
3108 #ifdef PNG_READ_GAMMA_SUPPORTED
3109 if (png_ptr->gamma_16_to_1 != NULL && png_ptr->gamma_16_from_1 != NULL)
3110 {
3111 png_bytep sp = row;
3112 png_bytep dp = row;
3113 png_uint_32 i;
3114
3115 for (i = 0; i < row_width; i++)
3116 {
3117 png_uint_16 red, green, blue, w;
3118
3119 red = (png_uint_16)(((*(sp)) << 8) | *(sp + 1)); sp += 2;
3120 green = (png_uint_16)(((*(sp)) << 8) | *(sp + 1)); sp += 2;
3121 blue = (png_uint_16)(((*(sp)) << 8) | *(sp + 1)); sp += 2;
3122
3123 if (red == green && red == blue)
3124 {
3125 if (png_ptr->gamma_16_table != NULL)
3126 w = png_ptr->gamma_16_table[(red & 0xff)
3127 >> png_ptr->gamma_shift][red >> 8];
3128
3129 else
3130 w = red;
3131 }
3132
3133 else
3134 {
3135 png_uint_16 red_1 = png_ptr->gamma_16_to_1[(red&0xff)
3136 >> png_ptr->gamma_shift][red>>8];
3137 png_uint_16 green_1 =
3138 png_ptr->gamma_16_to_1[(green&0xff) >>
3139 png_ptr->gamma_shift][green>>8];
3140 png_uint_16 blue_1 = png_ptr->gamma_16_to_1[(blue&0xff)
3141 >> png_ptr->gamma_shift][blue>>8];
3142 png_uint_16 gray16 = (png_uint_16)((rc*red_1 + gc*green_1
3143 + bc*blue_1 + 16384)>>15);
3144 w = png_ptr->gamma_16_from_1[(gray16&0xff) >>
3145 png_ptr->gamma_shift][gray16 >> 8];
3146 rgb_error |= 1;
3147 }
3148
3149 *(dp++) = (png_byte)((w>>8) & 0xff);
3150 *(dp++) = (png_byte)(w & 0xff);
3151
3152 if (have_alpha != 0)
3153 {
3154 *(dp++) = *(sp++);
3155 *(dp++) = *(sp++);
3156 }
3157 }
3158 }
3159 else
3160 #endif
3161 {
3162 png_bytep sp = row;
3163 png_bytep dp = row;
3164 png_uint_32 i;
3165
3166 for (i = 0; i < row_width; i++)
3167 {
3168 png_uint_16 red, green, blue, gray16;
3169
3170 red = (png_uint_16)(((*(sp)) << 8) | *(sp + 1)); sp += 2;
3171 green = (png_uint_16)(((*(sp)) << 8) | *(sp + 1)); sp += 2;
3172 blue = (png_uint_16)(((*(sp)) << 8) | *(sp + 1)); sp += 2;
3173
3174 if (red != green || red != blue)
3175 rgb_error |= 1;
3176
3177 /* From 1.5.5 in the 16 bit case do the accurate conversion even
3178 * in the 'fast' case - this is because this is where the code
3179 * ends up when handling linear 16 bit data.
3180 */
3181 gray16 = (png_uint_16)((rc*red + gc*green + bc*blue + 16384) >>
3182 15);
3183 *(dp++) = (png_byte)((gray16 >> 8) & 0xff);
3184 *(dp++) = (png_byte)(gray16 & 0xff);
3185
3186 if (have_alpha != 0)
3187 {
3188 *(dp++) = *(sp++);
3189 *(dp++) = *(sp++);
3190 }
3191 }
3192 }
3193 }
3194
3195 row_info->channels = (png_byte)(row_info->channels - 2);
3196 row_info->color_type = (png_byte)(row_info->color_type &
3197 ~PNG_COLOR_MASK_COLOR);
3198 row_info->pixel_depth = (png_byte)(row_info->channels *
3199 row_info->bit_depth);
3200 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
3201 }
3202 return rgb_error;
3203 }
3204 #endif
3205
3206 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
3207 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
3208 /* Replace any alpha or transparency with the supplied background color.
3209 * "background" is already in the screen gamma, while "background_1" is
3210 * at a gamma of 1.0. Paletted files have already been taken care of.
3211 */
3212 static void
3213 png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
3214 {
3215 #ifdef PNG_READ_GAMMA_SUPPORTED
3216 png_const_bytep gamma_table = png_ptr->gamma_table;
3217 png_const_bytep gamma_from_1 = png_ptr->gamma_from_1;
3218 png_const_bytep gamma_to_1 = png_ptr->gamma_to_1;
3219 png_const_uint_16pp gamma_16 = png_ptr->gamma_16_table;
3220 png_const_uint_16pp gamma_16_from_1 = png_ptr->gamma_16_from_1;
3221 png_const_uint_16pp gamma_16_to_1 = png_ptr->gamma_16_to_1;
3222 int gamma_shift = png_ptr->gamma_shift;
3223 int optimize = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0;
3224 #endif
3225
3226 png_bytep sp;
3227 png_uint_32 i;
3228 png_uint_32 row_width = row_info->width;
3229 int shift;
3230
3231 png_debug(1, "in png_do_compose");
3232
3233 {
3234 switch (row_info->color_type)
3235 {
3236 case PNG_COLOR_TYPE_GRAY:
3237 {
3238 switch (row_info->bit_depth)
3239 {
3240 case 1:
3241 {
3242 sp = row;
3243 shift = 7;
3244 for (i = 0; i < row_width; i++)
3245 {
3246 if ((png_uint_16)((*sp >> shift) & 0x01)
3247 == png_ptr->trans_color.gray)
3248 {
3249 unsigned int tmp = *sp & (0x7f7f >> (7 - shift));
3250 tmp |= png_ptr->background.gray << shift;
3251 *sp = (png_byte)(tmp & 0xff);
3252 }
3253
3254 if (shift == 0)
3255 {
3256 shift = 7;
3257 sp++;
3258 }
3259
3260 else
3261 shift--;
3262 }
3263 break;
3264 }
3265
3266 case 2:
3267 {
3268 #ifdef PNG_READ_GAMMA_SUPPORTED
3269 if (gamma_table != NULL)
3270 {
3271 sp = row;
3272 shift = 6;
3273 for (i = 0; i < row_width; i++)
3274 {
3275 if ((png_uint_16)((*sp >> shift) & 0x03)
3276 == png_ptr->trans_color.gray)
3277 {
3278 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3279 tmp |= png_ptr->background.gray << shift;
3280 *sp = (png_byte)(tmp & 0xff);
3281 }
3282
3283 else
3284 {
3285 unsigned int p = (*sp >> shift) & 0x03;
3286 unsigned int g = (gamma_table [p | (p << 2) |
3287 (p << 4) | (p << 6)] >> 6) & 0x03;
3288 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3289 tmp |= g << shift;
3290 *sp = (png_byte)(tmp & 0xff);
3291 }
3292
3293 if (shift == 0)
3294 {
3295 shift = 6;
3296 sp++;
3297 }
3298
3299 else
3300 shift -= 2;
3301 }
3302 }
3303
3304 else
3305 #endif
3306 {
3307 sp = row;
3308 shift = 6;
3309 for (i = 0; i < row_width; i++)
3310 {
3311 if ((png_uint_16)((*sp >> shift) & 0x03)
3312 == png_ptr->trans_color.gray)
3313 {
3314 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3315 tmp |= png_ptr->background.gray << shift;
3316 *sp = (png_byte)(tmp & 0xff);
3317 }
3318
3319 if (shift == 0)
3320 {
3321 shift = 6;
3322 sp++;
3323 }
3324
3325 else
3326 shift -= 2;
3327 }
3328 }
3329 break;
3330 }
3331
3332 case 4:
3333 {
3334 #ifdef PNG_READ_GAMMA_SUPPORTED
3335 if (gamma_table != NULL)
3336 {
3337 sp = row;
3338 shift = 4;
3339 for (i = 0; i < row_width; i++)
3340 {
3341 if ((png_uint_16)((*sp >> shift) & 0x0f)
3342 == png_ptr->trans_color.gray)
3343 {
3344 unsigned int tmp = *sp & (0xf0f >> (4 - shift));
3345 tmp |= png_ptr->background.gray << shift;
3346 *sp = (png_byte)(tmp & 0xff);
3347 }
3348
3349 else
3350 {
3351 unsigned int p = (*sp >> shift) & 0x0f;
3352 unsigned int g = (gamma_table[p | (p << 4)] >> 4) &
3353 0x0f;
3354 unsigned int tmp = *sp & (0xf0f >> (4 - shift));
3355 tmp |= g << shift;
3356 *sp = (png_byte)(tmp & 0xff);
3357 }
3358
3359 if (shift == 0)
3360 {
3361 shift = 4;
3362 sp++;
3363 }
3364
3365 else
3366 shift -= 4;
3367 }
3368 }
3369
3370 else
3371 #endif
3372 {
3373 sp = row;
3374 shift = 4;
3375 for (i = 0; i < row_width; i++)
3376 {
3377 if ((png_uint_16)((*sp >> shift) & 0x0f)
3378 == png_ptr->trans_color.gray)
3379 {
3380 unsigned int tmp = *sp & (0xf0f >> (4 - shift));
3381 tmp |= png_ptr->background.gray << shift;
3382 *sp = (png_byte)(tmp & 0xff);
3383 }
3384
3385 if (shift == 0)
3386 {
3387 shift = 4;
3388 sp++;
3389 }
3390
3391 else
3392 shift -= 4;
3393 }
3394 }
3395 break;
3396 }
3397
3398 case 8:
3399 {
3400 #ifdef PNG_READ_GAMMA_SUPPORTED
3401 if (gamma_table != NULL)
3402 {
3403 sp = row;
3404 for (i = 0; i < row_width; i++, sp++)
3405 {
3406 if (*sp == png_ptr->trans_color.gray)
3407 *sp = (png_byte)png_ptr->background.gray;
3408
3409 else
3410 *sp = gamma_table[*sp];
3411 }
3412 }
3413 else
3414 #endif
3415 {
3416 sp = row;
3417 for (i = 0; i < row_width; i++, sp++)
3418 {
3419 if (*sp == png_ptr->trans_color.gray)
3420 *sp = (png_byte)png_ptr->background.gray;
3421 }
3422 }
3423 break;
3424 }
3425
3426 case 16:
3427 {
3428 #ifdef PNG_READ_GAMMA_SUPPORTED
3429 if (gamma_16 != NULL)
3430 {
3431 sp = row;
3432 for (i = 0; i < row_width; i++, sp += 2)
3433 {
3434 png_uint_16 v;
3435
3436 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3437
3438 if (v == png_ptr->trans_color.gray)
3439 {
3440 /* Background is already in screen gamma */
3441 *sp = (png_byte)((png_ptr->background.gray >> 8)
3442 & 0xff);
3443 *(sp + 1) = (png_byte)(png_ptr->background.gray
3444 & 0xff);
3445 }
3446
3447 else
3448 {
3449 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3450 *sp = (png_byte)((v >> 8) & 0xff);
3451 *(sp + 1) = (png_byte)(v & 0xff);
3452 }
3453 }
3454 }
3455 else
3456 #endif
3457 {
3458 sp = row;
3459 for (i = 0; i < row_width; i++, sp += 2)
3460 {
3461 png_uint_16 v;
3462
3463 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3464
3465 if (v == png_ptr->trans_color.gray)
3466 {
3467 *sp = (png_byte)((png_ptr->background.gray >> 8)
3468 & 0xff);
3469 *(sp + 1) = (png_byte)(png_ptr->background.gray
3470 & 0xff);
3471 }
3472 }
3473 }
3474 break;
3475 }
3476
3477 default:
3478 break;
3479 }
3480 break;
3481 }
3482
3483 case PNG_COLOR_TYPE_RGB:
3484 {
3485 if (row_info->bit_depth == 8)
3486 {
3487 #ifdef PNG_READ_GAMMA_SUPPORTED
3488 if (gamma_table != NULL)
3489 {
3490 sp = row;
3491 for (i = 0; i < row_width; i++, sp += 3)
3492 {
3493 if (*sp == png_ptr->trans_color.red &&
3494 *(sp + 1) == png_ptr->trans_color.green &&
3495 *(sp + 2) == png_ptr->trans_color.blue)
3496 {
3497 *sp = (png_byte)png_ptr->background.red;
3498 *(sp + 1) = (png_byte)png_ptr->background.green;
3499 *(sp + 2) = (png_byte)png_ptr->background.blue;
3500 }
3501
3502 else
3503 {
3504 *sp = gamma_table[*sp];
3505 *(sp + 1) = gamma_table[*(sp + 1)];
3506 *(sp + 2) = gamma_table[*(sp + 2)];
3507 }
3508 }
3509 }
3510 else
3511 #endif
3512 {
3513 sp = row;
3514 for (i = 0; i < row_width; i++, sp += 3)
3515 {
3516 if (*sp == png_ptr->trans_color.red &&
3517 *(sp + 1) == png_ptr->trans_color.green &&
3518 *(sp + 2) == png_ptr->trans_color.blue)
3519 {
3520 *sp = (png_byte)png_ptr->background.red;
3521 *(sp + 1) = (png_byte)png_ptr->background.green;
3522 *(sp + 2) = (png_byte)png_ptr->background.blue;
3523 }
3524 }
3525 }
3526 }
3527 else /* if (row_info->bit_depth == 16) */
3528 {
3529 #ifdef PNG_READ_GAMMA_SUPPORTED
3530 if (gamma_16 != NULL)
3531 {
3532 sp = row;
3533 for (i = 0; i < row_width; i++, sp += 6)
3534 {
3535 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3536
3537 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3538 + *(sp + 3));
3539
3540 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3541 + *(sp + 5));
3542
3543 if (r == png_ptr->trans_color.red &&
3544 g == png_ptr->trans_color.green &&
3545 b == png_ptr->trans_color.blue)
3546 {
3547 /* Background is already in screen gamma */
3548 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3549 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3550 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3551 & 0xff);
3552 *(sp + 3) = (png_byte)(png_ptr->background.green
3553 & 0xff);
3554 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3555 & 0xff);
3556 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3557 }
3558
3559 else
3560 {
3561 png_uint_16 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3562 *sp = (png_byte)((v >> 8) & 0xff);
3563 *(sp + 1) = (png_byte)(v & 0xff);
3564
3565 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
3566 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3567 *(sp + 3) = (png_byte)(v & 0xff);
3568
3569 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
3570 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3571 *(sp + 5) = (png_byte)(v & 0xff);
3572 }
3573 }
3574 }
3575
3576 else
3577 #endif
3578 {
3579 sp = row;
3580 for (i = 0; i < row_width; i++, sp += 6)
3581 {
3582 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3583
3584 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3585 + *(sp + 3));
3586
3587 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3588 + *(sp + 5));
3589
3590 if (r == png_ptr->trans_color.red &&
3591 g == png_ptr->trans_color.green &&
3592 b == png_ptr->trans_color.blue)
3593 {
3594 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3595 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3596 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3597 & 0xff);
3598 *(sp + 3) = (png_byte)(png_ptr->background.green
3599 & 0xff);
3600 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3601 & 0xff);
3602 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3603 }
3604 }
3605 }
3606 }
3607 break;
3608 }
3609
3610 case PNG_COLOR_TYPE_GRAY_ALPHA:
3611 {
3612 if (row_info->bit_depth == 8)
3613 {
3614 #ifdef PNG_READ_GAMMA_SUPPORTED
3615 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
3616 gamma_table != NULL)
3617 {
3618 sp = row;
3619 for (i = 0; i < row_width; i++, sp += 2)
3620 {
3621 png_uint_16 a = *(sp + 1);
3622
3623 if (a == 0xff)
3624 *sp = gamma_table[*sp];
3625
3626 else if (a == 0)
3627 {
3628 /* Background is already in screen gamma */
3629 *sp = (png_byte)png_ptr->background.gray;
3630 }
3631
3632 else
3633 {
3634 png_byte v, w;
3635
3636 v = gamma_to_1[*sp];
3637 png_composite(w, v, a, png_ptr->background_1.gray);
3638 if (optimize == 0)
3639 w = gamma_from_1[w];
3640 *sp = w;
3641 }
3642 }
3643 }
3644 else
3645 #endif
3646 {
3647 sp = row;
3648 for (i = 0; i < row_width; i++, sp += 2)
3649 {
3650 png_byte a = *(sp + 1);
3651
3652 if (a == 0)
3653 *sp = (png_byte)png_ptr->background.gray;
3654
3655 else if (a < 0xff)
3656 png_composite(*sp, *sp, a, png_ptr->background.gray);
3657 }
3658 }
3659 }
3660 else /* if (png_ptr->bit_depth == 16) */
3661 {
3662 #ifdef PNG_READ_GAMMA_SUPPORTED
3663 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
3664 gamma_16_to_1 != NULL)
3665 {
3666 sp = row;
3667 for (i = 0; i < row_width; i++, sp += 4)
3668 {
3669 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
3670 + *(sp + 3));
3671
3672 if (a == (png_uint_16)0xffff)
3673 {
3674 png_uint_16 v;
3675
3676 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3677 *sp = (png_byte)((v >> 8) & 0xff);
3678 *(sp + 1) = (png_byte)(v & 0xff);
3679 }
3680
3681 else if (a == 0)
3682 {
3683 /* Background is already in screen gamma */
3684 *sp = (png_byte)((png_ptr->background.gray >> 8)
3685 & 0xff);
3686 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
3687 }
3688
3689 else
3690 {
3691 png_uint_16 g, v, w;
3692
3693 g = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
3694 png_composite_16(v, g, a, png_ptr->background_1.gray);
3695 if (optimize != 0)
3696 w = v;
3697 else
3698 w = gamma_16_from_1[(v&0xff) >> gamma_shift][v >> 8];
3699 *sp = (png_byte)((w >> 8) & 0xff);
3700 *(sp + 1) = (png_byte)(w & 0xff);
3701 }
3702 }
3703 }
3704 else
3705 #endif
3706 {
3707 sp = row;
3708 for (i = 0; i < row_width; i++, sp += 4)
3709 {
3710 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
3711 + *(sp + 3));
3712
3713 if (a == 0)
3714 {
3715 *sp = (png_byte)((png_ptr->background.gray >> 8)
3716 & 0xff);
3717 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
3718 }
3719
3720 else if (a < 0xffff)
3721 {
3722 png_uint_16 g, v;
3723
3724 g = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3725 png_composite_16(v, g, a, png_ptr->background.gray);
3726 *sp = (png_byte)((v >> 8) & 0xff);
3727 *(sp + 1) = (png_byte)(v & 0xff);
3728 }
3729 }
3730 }
3731 }
3732 break;
3733 }
3734
3735 case PNG_COLOR_TYPE_RGB_ALPHA:
3736 {
3737 if (row_info->bit_depth == 8)
3738 {
3739 #ifdef PNG_READ_GAMMA_SUPPORTED
3740 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
3741 gamma_table != NULL)
3742 {
3743 sp = row;
3744 for (i = 0; i < row_width; i++, sp += 4)
3745 {
3746 png_byte a = *(sp + 3);
3747
3748 if (a == 0xff)
3749 {
3750 *sp = gamma_table[*sp];
3751 *(sp + 1) = gamma_table[*(sp + 1)];
3752 *(sp + 2) = gamma_table[*(sp + 2)];
3753 }
3754
3755 else if (a == 0)
3756 {
3757 /* Background is already in screen gamma */
3758 *sp = (png_byte)png_ptr->background.red;
3759 *(sp + 1) = (png_byte)png_ptr->background.green;
3760 *(sp + 2) = (png_byte)png_ptr->background.blue;
3761 }
3762
3763 else
3764 {
3765 png_byte v, w;
3766
3767 v = gamma_to_1[*sp];
3768 png_composite(w, v, a, png_ptr->background_1.red);
3769 if (optimize == 0) w = gamma_from_1[w];
3770 *sp = w;
3771
3772 v = gamma_to_1[*(sp + 1)];
3773 png_composite(w, v, a, png_ptr->background_1.green);
3774 if (optimize == 0) w = gamma_from_1[w];
3775 *(sp + 1) = w;
3776
3777 v = gamma_to_1[*(sp + 2)];
3778 png_composite(w, v, a, png_ptr->background_1.blue);
3779 if (optimize == 0) w = gamma_from_1[w];
3780 *(sp + 2) = w;
3781 }
3782 }
3783 }
3784 else
3785 #endif
3786 {
3787 sp = row;
3788 for (i = 0; i < row_width; i++, sp += 4)
3789 {
3790 png_byte a = *(sp + 3);
3791
3792 if (a == 0)
3793 {
3794 *sp = (png_byte)png_ptr->background.red;
3795 *(sp + 1) = (png_byte)png_ptr->background.green;
3796 *(sp + 2) = (png_byte)png_ptr->background.blue;
3797 }
3798
3799 else if (a < 0xff)
3800 {
3801 png_composite(*sp, *sp, a, png_ptr->background.red);
3802
3803 png_composite(*(sp + 1), *(sp + 1), a,
3804 png_ptr->background.green);
3805
3806 png_composite(*(sp + 2), *(sp + 2), a,
3807 png_ptr->background.blue);
3808 }
3809 }
3810 }
3811 }
3812 else /* if (row_info->bit_depth == 16) */
3813 {
3814 #ifdef PNG_READ_GAMMA_SUPPORTED
3815 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
3816 gamma_16_to_1 != NULL)
3817 {
3818 sp = row;
3819 for (i = 0; i < row_width; i++, sp += 8)
3820 {
3821 png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
3822 << 8) + (png_uint_16)(*(sp + 7)));
3823
3824 if (a == (png_uint_16)0xffff)
3825 {
3826 png_uint_16 v;
3827
3828 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3829 *sp = (png_byte)((v >> 8) & 0xff);
3830 *(sp + 1) = (png_byte)(v & 0xff);
3831
3832 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
3833 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3834 *(sp + 3) = (png_byte)(v & 0xff);
3835
3836 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
3837 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3838 *(sp + 5) = (png_byte)(v & 0xff);
3839 }
3840
3841 else if (a == 0)
3842 {
3843 /* Background is already in screen gamma */
3844 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3845 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3846 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3847 & 0xff);
3848 *(sp + 3) = (png_byte)(png_ptr->background.green
3849 & 0xff);
3850 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3851 & 0xff);
3852 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3853 }
3854
3855 else
3856 {
3857 png_uint_16 v, w;
3858
3859 v = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
3860 png_composite_16(w, v, a, png_ptr->background_1.red);
3861 if (optimize == 0)
3862 w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >>
3863 8];
3864 *sp = (png_byte)((w >> 8) & 0xff);
3865 *(sp + 1) = (png_byte)(w & 0xff);
3866
3867 v = gamma_16_to_1[*(sp + 3) >> gamma_shift][*(sp + 2)];
3868 png_composite_16(w, v, a, png_ptr->background_1.green);
3869 if (optimize == 0)
3870 w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >>
3871 8];
3872
3873 *(sp + 2) = (png_byte)((w >> 8) & 0xff);
3874 *(sp + 3) = (png_byte)(w & 0xff);
3875
3876 v = gamma_16_to_1[*(sp + 5) >> gamma_shift][*(sp + 4)];
3877 png_composite_16(w, v, a, png_ptr->background_1.blue);
3878 if (optimize == 0)
3879 w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >>
3880 8];
3881
3882 *(sp + 4) = (png_byte)((w >> 8) & 0xff);
3883 *(sp + 5) = (png_byte)(w & 0xff);
3884 }
3885 }
3886 }
3887
3888 else
3889 #endif
3890 {
3891 sp = row;
3892 for (i = 0; i < row_width; i++, sp += 8)
3893 {
3894 png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
3895 << 8) + (png_uint_16)(*(sp + 7)));
3896
3897 if (a == 0)
3898 {
3899 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3900 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3901 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3902 & 0xff);
3903 *(sp + 3) = (png_byte)(png_ptr->background.green
3904 & 0xff);
3905 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3906 & 0xff);
3907 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3908 }
3909
3910 else if (a < 0xffff)
3911 {
3912 png_uint_16 v;
3913
3914 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3915 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3916 + *(sp + 3));
3917 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3918 + *(sp + 5));
3919
3920 png_composite_16(v, r, a, png_ptr->background.red);
3921 *sp = (png_byte)((v >> 8) & 0xff);
3922 *(sp + 1) = (png_byte)(v & 0xff);
3923
3924 png_composite_16(v, g, a, png_ptr->background.green);
3925 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3926 *(sp + 3) = (png_byte)(v & 0xff);
3927
3928 png_composite_16(v, b, a, png_ptr->background.blue);
3929 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3930 *(sp + 5) = (png_byte)(v & 0xff);
3931 }
3932 }
3933 }
3934 }
3935 break;
3936 }
3937
3938 default:
3939 break;
3940 }
3941 }
3942 }
3943 #endif /* READ_BACKGROUND || READ_ALPHA_MODE */
3944
3945 #ifdef PNG_READ_GAMMA_SUPPORTED
3946 /* Gamma correct the image, avoiding the alpha channel. Make sure
3947 * you do this after you deal with the transparency issue on grayscale
3948 * or RGB images. If your bit depth is 8, use gamma_table, if it
3949 * is 16, use gamma_16_table and gamma_shift. Build these with
3950 * build_gamma_table().
3951 */
3952 static void
3953 png_do_gamma(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
3954 {
3955 png_const_bytep gamma_table = png_ptr->gamma_table;
3956 png_const_uint_16pp gamma_16_table = png_ptr->gamma_16_table;
3957 int gamma_shift = png_ptr->gamma_shift;
3958
3959 png_bytep sp;
3960 png_uint_32 i;
3961 png_uint_32 row_width=row_info->width;
3962
3963 png_debug(1, "in png_do_gamma");
3964
3965 if (((row_info->bit_depth <= 8 && gamma_table != NULL) ||
3966 (row_info->bit_depth == 16 && gamma_16_table != NULL)))
3967 {
3968 switch (row_info->color_type)
3969 {
3970 case PNG_COLOR_TYPE_RGB:
3971 {
3972 if (row_info->bit_depth == 8)
3973 {
3974 sp = row;
3975 for (i = 0; i < row_width; i++)
3976 {
3977 *sp = gamma_table[*sp];
3978 sp++;
3979 *sp = gamma_table[*sp];
3980 sp++;
3981 *sp = gamma_table[*sp];
3982 sp++;
3983 }
3984 }
3985
3986 else /* if (row_info->bit_depth == 16) */
3987 {
3988 sp = row;
3989 for (i = 0; i < row_width; i++)
3990 {
3991 png_uint_16 v;
3992
3993 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
3994 *sp = (png_byte)((v >> 8) & 0xff);
3995 *(sp + 1) = (png_byte)(v & 0xff);
3996 sp += 2;
3997
3998 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
3999 *sp = (png_byte)((v >> 8) & 0xff);
4000 *(sp + 1) = (png_byte)(v & 0xff);
4001 sp += 2;
4002
4003 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4004 *sp = (png_byte)((v >> 8) & 0xff);
4005 *(sp + 1) = (png_byte)(v & 0xff);
4006 sp += 2;
4007 }
4008 }
4009 break;
4010 }
4011
4012 case PNG_COLOR_TYPE_RGB_ALPHA:
4013 {
4014 if (row_info->bit_depth == 8)
4015 {
4016 sp = row;
4017 for (i = 0; i < row_width; i++)
4018 {
4019 *sp = gamma_table[*sp];
4020 sp++;
4021
4022 *sp = gamma_table[*sp];
4023 sp++;
4024
4025 *sp = gamma_table[*sp];
4026 sp++;
4027
4028 sp++;
4029 }
4030 }
4031
4032 else /* if (row_info->bit_depth == 16) */
4033 {
4034 sp = row;
4035 for (i = 0; i < row_width; i++)
4036 {
4037 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4038 *sp = (png_byte)((v >> 8) & 0xff);
4039 *(sp + 1) = (png_byte)(v & 0xff);
4040 sp += 2;
4041
4042 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4043 *sp = (png_byte)((v >> 8) & 0xff);
4044 *(sp + 1) = (png_byte)(v & 0xff);
4045 sp += 2;
4046
4047 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4048 *sp = (png_byte)((v >> 8) & 0xff);
4049 *(sp + 1) = (png_byte)(v & 0xff);
4050 sp += 4;
4051 }
4052 }
4053 break;
4054 }
4055
4056 case PNG_COLOR_TYPE_GRAY_ALPHA:
4057 {
4058 if (row_info->bit_depth == 8)
4059 {
4060 sp = row;
4061 for (i = 0; i < row_width; i++)
4062 {
4063 *sp = gamma_table[*sp];
4064 sp += 2;
4065 }
4066 }
4067
4068 else /* if (row_info->bit_depth == 16) */
4069 {
4070 sp = row;
4071 for (i = 0; i < row_width; i++)
4072 {
4073 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4074 *sp = (png_byte)((v >> 8) & 0xff);
4075 *(sp + 1) = (png_byte)(v & 0xff);
4076 sp += 4;
4077 }
4078 }
4079 break;
4080 }
4081
4082 case PNG_COLOR_TYPE_GRAY:
4083 {
4084 if (row_info->bit_depth == 2)
4085 {
4086 sp = row;
4087 for (i = 0; i < row_width; i += 4)
4088 {
4089 int a = *sp & 0xc0;
4090 int b = *sp & 0x30;
4091 int c = *sp & 0x0c;
4092 int d = *sp & 0x03;
4093
4094 *sp = (png_byte)(
4095 ((((int)gamma_table[a|(a>>2)|(a>>4)|(a>>6)]) ) & 0xc0)|
4096 ((((int)gamma_table[(b<<2)|b|(b>>2)|(b>>4)])>>2) & 0x30)|
4097 ((((int)gamma_table[(c<<4)|(c<<2)|c|(c>>2)])>>4) & 0x0c)|
4098 ((((int)gamma_table[(d<<6)|(d<<4)|(d<<2)|d])>>6) ));
4099 sp++;
4100 }
4101 }
4102
4103 if (row_info->bit_depth == 4)
4104 {
4105 sp = row;
4106 for (i = 0; i < row_width; i += 2)
4107 {
4108 int msb = *sp & 0xf0;
4109 int lsb = *sp & 0x0f;
4110
4111 *sp = (png_byte)((((int)gamma_table[msb | (msb >> 4)]) & 0xf0)
4112 | (((int)gamma_table[(lsb << 4) | lsb]) >> 4));
4113 sp++;
4114 }
4115 }
4116
4117 else if (row_info->bit_depth == 8)
4118 {
4119 sp = row;
4120 for (i = 0; i < row_width; i++)
4121 {
4122 *sp = gamma_table[*sp];
4123 sp++;
4124 }
4125 }
4126
4127 else if (row_info->bit_depth == 16)
4128 {
4129 sp = row;
4130 for (i = 0; i < row_width; i++)
4131 {
4132 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4133 *sp = (png_byte)((v >> 8) & 0xff);
4134 *(sp + 1) = (png_byte)(v & 0xff);
4135 sp += 2;
4136 }
4137 }
4138 break;
4139 }
4140
4141 default:
4142 break;
4143 }
4144 }
4145 }
4146 #endif
4147
4148 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
4149 /* Encode the alpha channel to the output gamma (the input channel is always
4150 * linear.) Called only with color types that have an alpha channel. Needs the
4151 * from_1 tables.
4152 */
4153 static void
4154 png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
4155 {
4156 png_uint_32 row_width = row_info->width;
4157
4158 png_debug(1, "in png_do_encode_alpha");
4159
4160 if ((row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
4161 {
4162 if (row_info->bit_depth == 8)
4163 {
4164 PNG_CONST png_bytep table = png_ptr->gamma_from_1;
4165
4166 if (table != NULL)
4167 {
4168 PNG_CONST int step =
4169 (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 4 : 2;
4170
4171 /* The alpha channel is the last component: */
4172 row += step - 1;
4173
4174 for (; row_width > 0; --row_width, row += step)
4175 *row = table[*row];
4176
4177 return;
4178 }
4179 }
4180
4181 else if (row_info->bit_depth == 16)
4182 {
4183 PNG_CONST png_uint_16pp table = png_ptr->gamma_16_from_1;
4184 PNG_CONST int gamma_shift = png_ptr->gamma_shift;
4185
4186 if (table != NULL)
4187 {
4188 PNG_CONST int step =
4189 (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 8 : 4;
4190
4191 /* The alpha channel is the last component: */
4192 row += step - 2;
4193
4194 for (; row_width > 0; --row_width, row += step)
4195 {
4196 png_uint_16 v;
4197
4198 v = table[*(row + 1) >> gamma_shift][*row];
4199 *row = (png_byte)((v >> 8) & 0xff);
4200 *(row + 1) = (png_byte)(v & 0xff);
4201 }
4202
4203 return;
4204 }
4205 }
4206 }
4207
4208 /* Only get to here if called with a weird row_info; no harm has been done,
4209 * so just issue a warning.
4210 */
4211 png_warning(png_ptr, "png_do_encode_alpha: unexpected call");
4212 }
4213 #endif
4214
4215 #ifdef PNG_READ_EXPAND_SUPPORTED
4216 /* Expands a palette row to an RGB or RGBA row depending
4217 * upon whether you supply trans and num_trans.
4218 */
4219 static void
4220 png_do_expand_palette(png_row_infop row_info, png_bytep row,
4221 png_const_colorp palette, png_const_bytep trans_alpha, int num_trans)
4222 {
4223 int shift, value;
4224 png_bytep sp, dp;
4225 png_uint_32 i;
4226 png_uint_32 row_width=row_info->width;
4227
4228 png_debug(1, "in png_do_expand_palette");
4229
4230 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
4231 {
4232 if (row_info->bit_depth < 8)
4233 {
4234 switch (row_info->bit_depth)
4235 {
4236 case 1:
4237 {
4238 sp = row + (png_size_t)((row_width - 1) >> 3);
4239 dp = row + (png_size_t)row_width - 1;
4240 shift = 7 - (int)((row_width + 7) & 0x07);
4241 for (i = 0; i < row_width; i++)
4242 {
4243 if ((*sp >> shift) & 0x01)
4244 *dp = 1;
4245
4246 else
4247 *dp = 0;
4248
4249 if (shift == 7)
4250 {
4251 shift = 0;
4252 sp--;
4253 }
4254
4255 else
4256 shift++;
4257
4258 dp--;
4259 }
4260 break;
4261 }
4262
4263 case 2:
4264 {
4265 sp = row + (png_size_t)((row_width - 1) >> 2);
4266 dp = row + (png_size_t)row_width - 1;
4267 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
4268 for (i = 0; i < row_width; i++)
4269 {
4270 value = (*sp >> shift) & 0x03;
4271 *dp = (png_byte)value;
4272 if (shift == 6)
4273 {
4274 shift = 0;
4275 sp--;
4276 }
4277
4278 else
4279 shift += 2;
4280
4281 dp--;
4282 }
4283 break;
4284 }
4285
4286 case 4:
4287 {
4288 sp = row + (png_size_t)((row_width - 1) >> 1);
4289 dp = row + (png_size_t)row_width - 1;
4290 shift = (int)((row_width & 0x01) << 2);
4291 for (i = 0; i < row_width; i++)
4292 {
4293 value = (*sp >> shift) & 0x0f;
4294 *dp = (png_byte)value;
4295 if (shift == 4)
4296 {
4297 shift = 0;
4298 sp--;
4299 }
4300
4301 else
4302 shift += 4;
4303
4304 dp--;
4305 }
4306 break;
4307 }
4308
4309 default:
4310 break;
4311 }
4312 row_info->bit_depth = 8;
4313 row_info->pixel_depth = 8;
4314 row_info->rowbytes = row_width;
4315 }
4316
4317 if (row_info->bit_depth == 8)
4318 {
4319 {
4320 if (num_trans > 0)
4321 {
4322 sp = row + (png_size_t)row_width - 1;
4323 dp = row + (png_size_t)(row_width << 2) - 1;
4324
4325 for (i = 0; i < row_width; i++)
4326 {
4327 if ((int)(*sp) >= num_trans)
4328 *dp-- = 0xff;
4329
4330 else
4331 *dp-- = trans_alpha[*sp];
4332
4333 *dp-- = palette[*sp].blue;
4334 *dp-- = palette[*sp].green;
4335 *dp-- = palette[*sp].red;
4336 sp--;
4337 }
4338 row_info->bit_depth = 8;
4339 row_info->pixel_depth = 32;
4340 row_info->rowbytes = row_width * 4;
4341 row_info->color_type = 6;
4342 row_info->channels = 4;
4343 }
4344
4345 else
4346 {
4347 sp = row + (png_size_t)row_width - 1;
4348 dp = row + (png_size_t)(row_width * 3) - 1;
4349
4350 for (i = 0; i < row_width; i++)
4351 {
4352 *dp-- = palette[*sp].blue;
4353 *dp-- = palette[*sp].green;
4354 *dp-- = palette[*sp].red;
4355 sp--;
4356 }
4357
4358 row_info->bit_depth = 8;
4359 row_info->pixel_depth = 24;
4360 row_info->rowbytes = row_width * 3;
4361 row_info->color_type = 2;
4362 row_info->channels = 3;
4363 }
4364 }
4365 }
4366 }
4367 }
4368
4369 /* If the bit depth < 8, it is expanded to 8. Also, if the already
4370 * expanded transparency value is supplied, an alpha channel is built.
4371 */
4372 static void
4373 png_do_expand(png_row_infop row_info, png_bytep row,
4374 png_const_color_16p trans_color)
4375 {
4376 int shift, value;
4377 png_bytep sp, dp;
4378 png_uint_32 i;
4379 png_uint_32 row_width=row_info->width;
4380
4381 png_debug(1, "in png_do_expand");
4382
4383 {
4384 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
4385 {
4386 unsigned int gray = trans_color != NULL ? trans_color->gray : 0;
4387
4388 if (row_info->bit_depth < 8)
4389 {
4390 switch (row_info->bit_depth)
4391 {
4392 case 1:
4393 {
4394 gray = (gray & 0x01) * 0xff;
4395 sp = row + (png_size_t)((row_width - 1) >> 3);
4396 dp = row + (png_size_t)row_width - 1;
4397 shift = 7 - (int)((row_width + 7) & 0x07);
4398 for (i = 0; i < row_width; i++)
4399 {
4400 if ((*sp >> shift) & 0x01)
4401 *dp = 0xff;
4402
4403 else
4404 *dp = 0;
4405
4406 if (shift == 7)
4407 {
4408 shift = 0;
4409 sp--;
4410 }
4411
4412 else
4413 shift++;
4414
4415 dp--;
4416 }
4417 break;
4418 }
4419
4420 case 2:
4421 {
4422 gray = (gray & 0x03) * 0x55;
4423 sp = row + (png_size_t)((row_width - 1) >> 2);
4424 dp = row + (png_size_t)row_width - 1;
4425 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
4426 for (i = 0; i < row_width; i++)
4427 {
4428 value = (*sp >> shift) & 0x03;
4429 *dp = (png_byte)(value | (value << 2) | (value << 4) |
4430 (value << 6));
4431 if (shift == 6)
4432 {
4433 shift = 0;
4434 sp--;
4435 }
4436
4437 else
4438 shift += 2;
4439
4440 dp--;
4441 }
4442 break;
4443 }
4444
4445 case 4:
4446 {
4447 gray = (gray & 0x0f) * 0x11;
4448 sp = row + (png_size_t)((row_width - 1) >> 1);
4449 dp = row + (png_size_t)row_width - 1;
4450 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
4451 for (i = 0; i < row_width; i++)
4452 {
4453 value = (*sp >> shift) & 0x0f;
4454 *dp = (png_byte)(value | (value << 4));
4455 if (shift == 4)
4456 {
4457 shift = 0;
4458 sp--;
4459 }
4460
4461 else
4462 shift = 4;
4463
4464 dp--;
4465 }
4466 break;
4467 }
4468
4469 default:
4470 break;
4471 }
4472
4473 row_info->bit_depth = 8;
4474 row_info->pixel_depth = 8;
4475 row_info->rowbytes = row_width;
4476 }
4477
4478 if (trans_color != NULL)
4479 {
4480 if (row_info->bit_depth == 8)
4481 {
4482 gray = gray & 0xff;
4483 sp = row + (png_size_t)row_width - 1;
4484 dp = row + (png_size_t)(row_width << 1) - 1;
4485
4486 for (i = 0; i < row_width; i++)
4487 {
4488 if (*sp == gray)
4489 *dp-- = 0;
4490
4491 else
4492 *dp-- = 0xff;
4493
4494 *dp-- = *sp--;
4495 }
4496 }
4497
4498 else if (row_info->bit_depth == 16)
4499 {
4500 unsigned int gray_high = (gray >> 8) & 0xff;
4501 unsigned int gray_low = gray & 0xff;
4502 sp = row + row_info->rowbytes - 1;
4503 dp = row + (row_info->rowbytes << 1) - 1;
4504 for (i = 0; i < row_width; i++)
4505 {
4506 if (*(sp - 1) == gray_high && *(sp) == gray_low)
4507 {
4508 *dp-- = 0;
4509 *dp-- = 0;
4510 }
4511
4512 else
4513 {
4514 *dp-- = 0xff;
4515 *dp-- = 0xff;
4516 }
4517
4518 *dp-- = *sp--;
4519 *dp-- = *sp--;
4520 }
4521 }
4522
4523 row_info->color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
4524 row_info->channels = 2;
4525 row_info->pixel_depth = (png_byte)(row_info->bit_depth << 1);
4526 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
4527 row_width);
4528 }
4529 }
4530 else if (row_info->color_type == PNG_COLOR_TYPE_RGB &&
4531 trans_color != NULL)
4532 {
4533 if (row_info->bit_depth == 8)
4534 {
4535 png_byte red = (png_byte)(trans_color->red & 0xff);
4536 png_byte green = (png_byte)(trans_color->green & 0xff);
4537 png_byte blue = (png_byte)(trans_color->blue & 0xff);
4538 sp = row + (png_size_t)row_info->rowbytes - 1;
4539 dp = row + (png_size_t)(row_width << 2) - 1;
4540 for (i = 0; i < row_width; i++)
4541 {
4542 if (*(sp - 2) == red && *(sp - 1) == green && *(sp) == blue)
4543 *dp-- = 0;
4544
4545 else
4546 *dp-- = 0xff;
4547
4548 *dp-- = *sp--;
4549 *dp-- = *sp--;
4550 *dp-- = *sp--;
4551 }
4552 }
4553 else if (row_info->bit_depth == 16)
4554 {
4555 png_byte red_high = (png_byte)((trans_color->red >> 8) & 0xff);
4556 png_byte green_high = (png_byte)((trans_color->green >> 8) & 0xff);
4557 png_byte blue_high = (png_byte)((trans_color->blue >> 8) & 0xff);
4558 png_byte red_low = (png_byte)(trans_color->red & 0xff);
4559 png_byte green_low = (png_byte)(trans_color->green & 0xff);
4560 png_byte blue_low = (png_byte)(trans_color->blue & 0xff);
4561 sp = row + row_info->rowbytes - 1;
4562 dp = row + (png_size_t)(row_width << 3) - 1;
4563 for (i = 0; i < row_width; i++)
4564 {
4565 if (*(sp - 5) == red_high &&
4566 *(sp - 4) == red_low &&
4567 *(sp - 3) == green_high &&
4568 *(sp - 2) == green_low &&
4569 *(sp - 1) == blue_high &&
4570 *(sp ) == blue_low)
4571 {
4572 *dp-- = 0;
4573 *dp-- = 0;
4574 }
4575
4576 else
4577 {
4578 *dp-- = 0xff;
4579 *dp-- = 0xff;
4580 }
4581
4582 *dp-- = *sp--;
4583 *dp-- = *sp--;
4584 *dp-- = *sp--;
4585 *dp-- = *sp--;
4586 *dp-- = *sp--;
4587 *dp-- = *sp--;
4588 }
4589 }
4590 row_info->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
4591 row_info->channels = 4;
4592 row_info->pixel_depth = (png_byte)(row_info->bit_depth << 2);
4593 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4594 }
4595 }
4596 }
4597 #endif
4598
4599 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4600 /* If the bit depth is 8 and the color type is not a palette type expand the
4601 * whole row to 16 bits. Has no effect otherwise.
4602 */
4603 static void
4604 png_do_expand_16(png_row_infop row_info, png_bytep row)
4605 {
4606 if (row_info->bit_depth == 8 &&
4607 row_info->color_type != PNG_COLOR_TYPE_PALETTE)
4608 {
4609 /* The row have a sequence of bytes containing [0..255] and we need
4610 * to turn it into another row containing [0..65535], to do this we
4611 * calculate:
4612 *
4613 * (input / 255) * 65535
4614 *
4615 * Which happens to be exactly input * 257 and this can be achieved
4616 * simply by byte replication in place (copying backwards).
4617 */
4618 png_byte *sp = row + row_info->rowbytes; /* source, last byte + 1 */
4619 png_byte *dp = sp + row_info->rowbytes; /* destination, end + 1 */
4620 while (dp > sp)
4621 dp[-2] = dp[-1] = *--sp, dp -= 2;
4622
4623 row_info->rowbytes *= 2;
4624 row_info->bit_depth = 16;
4625 row_info->pixel_depth = (png_byte)(row_info->channels * 16);
4626 }
4627 }
4628 #endif
4629
4630 #ifdef PNG_READ_QUANTIZE_SUPPORTED
4631 static void
4632 png_do_quantize(png_row_infop row_info, png_bytep row,
4633 png_const_bytep palette_lookup, png_const_bytep quantize_lookup)
4634 {
4635 png_bytep sp, dp;
4636 png_uint_32 i;
4637 png_uint_32 row_width=row_info->width;
4638
4639 png_debug(1, "in png_do_quantize");
4640
4641 if (row_info->bit_depth == 8)
4642 {
4643 if (row_info->color_type == PNG_COLOR_TYPE_RGB && palette_lookup)
4644 {
4645 int r, g, b, p;
4646 sp = row;
4647 dp = row;
4648 for (i = 0; i < row_width; i++)
4649 {
4650 r = *sp++;
4651 g = *sp++;
4652 b = *sp++;
4653
4654 /* This looks real messy, but the compiler will reduce
4655 * it down to a reasonable formula. For example, with
4656 * 5 bits per color, we get:
4657 * p = (((r >> 3) & 0x1f) << 10) |
4658 * (((g >> 3) & 0x1f) << 5) |
4659 * ((b >> 3) & 0x1f);
4660 */
4661 p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
4662 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
4663 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
4664 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
4665 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
4666 (PNG_QUANTIZE_BLUE_BITS)) |
4667 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
4668 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
4669
4670 *dp++ = palette_lookup[p];
4671 }
4672
4673 row_info->color_type = PNG_COLOR_TYPE_PALETTE;
4674 row_info->channels = 1;
4675 row_info->pixel_depth = row_info->bit_depth;
4676 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4677 }
4678
4679 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
4680 palette_lookup != NULL)
4681 {
4682 int r, g, b, p;
4683 sp = row;
4684 dp = row;
4685 for (i = 0; i < row_width; i++)
4686 {
4687 r = *sp++;
4688 g = *sp++;
4689 b = *sp++;
4690 sp++;
4691
4692 p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
4693 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
4694 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
4695 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
4696 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
4697 (PNG_QUANTIZE_BLUE_BITS)) |
4698 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
4699 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
4700
4701 *dp++ = palette_lookup[p];
4702 }
4703
4704 row_info->color_type = PNG_COLOR_TYPE_PALETTE;
4705 row_info->channels = 1;
4706 row_info->pixel_depth = row_info->bit_depth;
4707 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4708 }
4709
4710 else if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
4711 quantize_lookup)
4712 {
4713 sp = row;
4714
4715 for (i = 0; i < row_width; i++, sp++)
4716 {
4717 *sp = quantize_lookup[*sp];
4718 }
4719 }
4720 }
4721 }
4722 #endif /* READ_QUANTIZE */
4723
4724 /* Transform the row. The order of transformations is significant,
4725 * and is very touchy. If you add a transformation, take care to
4726 * decide how it fits in with the other transformations here.
4727 */
4728 void /* PRIVATE */
4729 png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
4730 {
4731 png_debug(1, "in png_do_read_transformations");
4732
4733 if (png_ptr->row_buf == NULL)
4734 {
4735 /* Prior to 1.5.4 this output row/pass where the NULL pointer is, but this
4736 * error is incredibly rare and incredibly easy to debug without this
4737 * information.
4738 */
4739 png_error(png_ptr, "NULL row buffer");
4740 }
4741
4742 /* The following is debugging; prior to 1.5.4 the code was never compiled in;
4743 * in 1.5.4 PNG_FLAG_DETECT_UNINITIALIZED was added and the macro
4744 * PNG_WARN_UNINITIALIZED_ROW removed. In 1.6 the new flag is set only for
4745 * all transformations, however in practice the ROW_INIT always gets done on
4746 * demand, if necessary.
4747 */
4748 if ((png_ptr->flags & PNG_FLAG_DETECT_UNINITIALIZED) != 0 &&
4749 (png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
4750 {
4751 /* Application has failed to call either png_read_start_image() or
4752 * png_read_update_info() after setting transforms that expand pixels.
4753 * This check added to libpng-1.2.19 (but not enabled until 1.5.4).
4754 */
4755 png_error(png_ptr, "Uninitialized row");
4756 }
4757
4758 #ifdef PNG_READ_EXPAND_SUPPORTED
4759 if ((png_ptr->transformations & PNG_EXPAND) != 0)
4760 {
4761 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
4762 {
4763 png_do_expand_palette(row_info, png_ptr->row_buf + 1,
4764 png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans);
4765 }
4766
4767 else
4768 {
4769 if (png_ptr->num_trans != 0 &&
4770 (png_ptr->transformations & PNG_EXPAND_tRNS) != 0)
4771 png_do_expand(row_info, png_ptr->row_buf + 1,
4772 &(png_ptr->trans_color));
4773
4774 else
4775 png_do_expand(row_info, png_ptr->row_buf + 1,
4776 NULL);
4777 }
4778 }
4779 #endif
4780
4781 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
4782 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
4783 (png_ptr->transformations & PNG_COMPOSE) == 0 &&
4784 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
4785 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
4786 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
4787 0 /* at_start == false, because SWAP_ALPHA happens later */);
4788 #endif
4789
4790 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
4791 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
4792 {
4793 int rgb_error =
4794 png_do_rgb_to_gray(png_ptr, row_info,
4795 png_ptr->row_buf + 1);
4796
4797 if (rgb_error != 0)
4798 {
4799 png_ptr->rgb_to_gray_status=1;
4800 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
4801 PNG_RGB_TO_GRAY_WARN)
4802 png_warning(png_ptr, "png_do_rgb_to_gray found nongray pixel");
4803
4804 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
4805 PNG_RGB_TO_GRAY_ERR)
4806 png_error(png_ptr, "png_do_rgb_to_gray found nongray pixel");
4807 }
4808 }
4809 #endif
4810
4811 /* From Andreas Dilger e-mail to png-implement, 26 March 1998:
4812 *
4813 * In most cases, the "simple transparency" should be done prior to doing
4814 * gray-to-RGB, or you will have to test 3x as many bytes to check if a
4815 * pixel is transparent. You would also need to make sure that the
4816 * transparency information is upgraded to RGB.
4817 *
4818 * To summarize, the current flow is:
4819 * - Gray + simple transparency -> compare 1 or 2 gray bytes and composite
4820 * with background "in place" if transparent,
4821 * convert to RGB if necessary
4822 * - Gray + alpha -> composite with gray background and remove alpha bytes,
4823 * convert to RGB if necessary
4824 *
4825 * To support RGB backgrounds for gray images we need:
4826 * - Gray + simple transparency -> convert to RGB + simple transparency,
4827 * compare 3 or 6 bytes and composite with
4828 * background "in place" if transparent
4829 * (3x compare/pixel compared to doing
4830 * composite with gray bkgrnd)
4831 * - Gray + alpha -> convert to RGB + alpha, composite with background and
4832 * remove alpha bytes (3x float
4833 * operations/pixel compared with composite
4834 * on gray background)
4835 *
4836 * Greg's change will do this. The reason it wasn't done before is for
4837 * performance, as this increases the per-pixel operations. If we would check
4838 * in advance if the background was gray or RGB, and position the gray-to-RGB
4839 * transform appropriately, then it would save a lot of work/time.
4840 */
4841
4842 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4843 /* If gray -> RGB, do so now only if background is non-gray; else do later
4844 * for performance reasons
4845 */
4846 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 &&
4847 (png_ptr->mode & PNG_BACKGROUND_IS_GRAY) == 0)
4848 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
4849 #endif
4850
4851 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
4852 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
4853 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
4854 png_do_compose(row_info, png_ptr->row_buf + 1, png_ptr);
4855 #endif
4856
4857 #ifdef PNG_READ_GAMMA_SUPPORTED
4858 if ((png_ptr->transformations & PNG_GAMMA) != 0 &&
4859 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
4860 /* Because RGB_TO_GRAY does the gamma transform. */
4861 (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0 &&
4862 #endif
4863 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
4864 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
4865 /* Because PNG_COMPOSE does the gamma transform if there is something to
4866 * do (if there is an alpha channel or transparency.)
4867 */
4868 !((png_ptr->transformations & PNG_COMPOSE) &&
4869 ((png_ptr->num_trans != 0) ||
4870 (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)) &&
4871 #endif
4872 /* Because png_init_read_transformations transforms the palette, unless
4873 * RGB_TO_GRAY will do the transform.
4874 */
4875 (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE))
4876 png_do_gamma(row_info, png_ptr->row_buf + 1, png_ptr);
4877 #endif
4878
4879 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
4880 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
4881 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
4882 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
4883 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
4884 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
4885 0 /* at_start == false, because SWAP_ALPHA happens later */);
4886 #endif
4887
4888 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
4889 if ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 &&
4890 (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
4891 png_do_encode_alpha(row_info, png_ptr->row_buf + 1, png_ptr);
4892 #endif
4893
4894 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
4895 if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0)
4896 png_do_scale_16_to_8(row_info, png_ptr->row_buf + 1);
4897 #endif
4898
4899 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
4900 /* There is no harm in doing both of these because only one has any effect,
4901 * by putting the 'scale' option first if the app asks for scale (either by
4902 * calling the API or in a TRANSFORM flag) this is what happens.
4903 */
4904 if ((png_ptr->transformations & PNG_16_TO_8) != 0)
4905 png_do_chop(row_info, png_ptr->row_buf + 1);
4906 #endif
4907
4908 #ifdef PNG_READ_QUANTIZE_SUPPORTED
4909 if ((png_ptr->transformations & PNG_QUANTIZE) != 0)
4910 {
4911 png_do_quantize(row_info, png_ptr->row_buf + 1,
4912 png_ptr->palette_lookup, png_ptr->quantize_index);
4913
4914 if (row_info->rowbytes == 0)
4915 png_error(png_ptr, "png_do_quantize returned rowbytes=0");
4916 }
4917 #endif /* READ_QUANTIZE */
4918
4919 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4920 /* Do the expansion now, after all the arithmetic has been done. Notice
4921 * that previous transformations can handle the PNG_EXPAND_16 flag if this
4922 * is efficient (particularly true in the case of gamma correction, where
4923 * better accuracy results faster!)
4924 */
4925 if ((png_ptr->transformations & PNG_EXPAND_16) != 0)
4926 png_do_expand_16(row_info, png_ptr->row_buf + 1);
4927 #endif
4928
4929 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4930 /* NOTE: moved here in 1.5.4 (from much later in this list.) */
4931 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 &&
4932 (png_ptr->mode & PNG_BACKGROUND_IS_GRAY) != 0)
4933 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
4934 #endif
4935
4936 #ifdef PNG_READ_INVERT_SUPPORTED
4937 if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
4938 png_do_invert(row_info, png_ptr->row_buf + 1);
4939 #endif
4940
4941 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
4942 if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
4943 png_do_read_invert_alpha(row_info, png_ptr->row_buf + 1);
4944 #endif
4945
4946 #ifdef PNG_READ_SHIFT_SUPPORTED
4947 if ((png_ptr->transformations & PNG_SHIFT) != 0)
4948 png_do_unshift(row_info, png_ptr->row_buf + 1,
4949 &(png_ptr->shift));
4950 #endif
4951
4952 #ifdef PNG_READ_PACK_SUPPORTED
4953 if ((png_ptr->transformations & PNG_PACK) != 0)
4954 png_do_unpack(row_info, png_ptr->row_buf + 1);
4955 #endif
4956
4957 #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
4958 /* Added at libpng-1.5.10 */
4959 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
4960 png_ptr->num_palette_max >= 0)
4961 png_do_check_palette_indexes(png_ptr, row_info);
4962 #endif
4963
4964 #ifdef PNG_READ_BGR_SUPPORTED
4965 if ((png_ptr->transformations & PNG_BGR) != 0)
4966 png_do_bgr(row_info, png_ptr->row_buf + 1);
4967 #endif
4968
4969 #ifdef PNG_READ_PACKSWAP_SUPPORTED
4970 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
4971 png_do_packswap(row_info, png_ptr->row_buf + 1);
4972 #endif
4973
4974 #ifdef PNG_READ_FILLER_SUPPORTED
4975 if ((png_ptr->transformations & PNG_FILLER) != 0)
4976 png_do_read_filler(row_info, png_ptr->row_buf + 1,
4977 (png_uint_32)png_ptr->filler, png_ptr->flags);
4978 #endif
4979
4980 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
4981 if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0)
4982 png_do_read_swap_alpha(row_info, png_ptr->row_buf + 1);
4983 #endif
4984
4985 #ifdef PNG_READ_16BIT_SUPPORTED
4986 #ifdef PNG_READ_SWAP_SUPPORTED
4987 if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
4988 png_do_swap(row_info, png_ptr->row_buf + 1);
4989 #endif
4990 #endif
4991
4992 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
4993 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
4994 {
4995 if (png_ptr->read_user_transform_fn != NULL)
4996 (*(png_ptr->read_user_transform_fn)) /* User read transform function */
4997 (png_ptr, /* png_ptr */
4998 row_info, /* row_info: */
4999 /* png_uint_32 width; width of row */
5000 /* png_size_t rowbytes; number of bytes in row */
5001 /* png_byte color_type; color type of pixels */
5002 /* png_byte bit_depth; bit depth of samples */
5003 /* png_byte channels; number of channels (1-4) */
5004 /* png_byte pixel_depth; bits per pixel (depth*channels) */
5005 png_ptr->row_buf + 1); /* start of pixel data for row */
5006 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
5007 if (png_ptr->user_transform_depth != 0)
5008 row_info->bit_depth = png_ptr->user_transform_depth;
5009
5010 if (png_ptr->user_transform_channels != 0)
5011 row_info->channels = png_ptr->user_transform_channels;
5012 #endif
5013 row_info->pixel_depth = (png_byte)(row_info->bit_depth *
5014 row_info->channels);
5015
5016 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_info->width);
5017 }
5018 #endif
5019 }
5020
5021 #endif /* READ_TRANSFORMS */
5022 #endif /* READ */