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 1.6.22 [May 26, 2016]
33 * Copyright (c) 1998-2002,2004,2006-2016 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 * 1.6.x: changed from 0.07..3 to 0.01..100 (to accomodate the optimal 16-bit
323 * gamma of 36, and its reciprocal.)
324 */
325 if (output_gamma < 1000 || output_gamma > 10000000)
326 png_error(png_ptr, "output gamma out of expected range");
327
328 /* The default file gamma is the inverse of the output gamma; the output
329 * gamma may be changed below so get the file value first:
330 */
331 file_gamma = png_reciprocal(output_gamma);
332
333 /* There are really 8 possibilities here, composed of any combination
334 * of:
335 *
336 * premultiply the color channels
337 * do not encode non-opaque pixels
338 * encode the alpha as well as the color channels
339 *
340 * The differences disappear if the input/output ('screen') gamma is 1.0,
341 * because then the encoding is a no-op and there is only the choice of
342 * premultiplying the color channels or not.
343 *
344 * png_set_alpha_mode and png_set_background interact because both use
345 * png_compose to do the work. Calling both is only useful when
346 * png_set_alpha_mode is used to set the default mode - PNG_ALPHA_PNG - along
347 * with a default gamma value. Otherwise PNG_COMPOSE must not be set.
348 */
349 switch (mode)
350 {
351 case PNG_ALPHA_PNG: /* default: png standard */
352 /* No compose, but it may be set by png_set_background! */
353 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
354 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
355 break;
356
357 case PNG_ALPHA_ASSOCIATED: /* color channels premultiplied */
358 compose = 1;
359 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
360 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
361 /* The output is linear: */
362 output_gamma = PNG_FP_1;
363 break;
364
365 case PNG_ALPHA_OPTIMIZED: /* associated, non-opaque pixels linear */
366 compose = 1;
367 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
368 png_ptr->flags |= PNG_FLAG_OPTIMIZE_ALPHA;
369 /* output_gamma records the encoding of opaque pixels! */
370 break;
371
372 case PNG_ALPHA_BROKEN: /* associated, non-linear, alpha encoded */
373 compose = 1;
374 png_ptr->transformations |= PNG_ENCODE_ALPHA;
375 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
376 break;
377
378 default:
379 png_error(png_ptr, "invalid alpha mode");
380 }
381
382 /* Only set the default gamma if the file gamma has not been set (this has
383 * the side effect that the gamma in a second call to png_set_alpha_mode will
384 * be ignored.)
385 */
386 if (png_ptr->colorspace.gamma == 0)
387 {
388 png_ptr->colorspace.gamma = file_gamma;
389 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
390 }
391
392 /* But always set the output gamma: */
393 png_ptr->screen_gamma = output_gamma;
394
395 /* Finally, if pre-multiplying, set the background fields to achieve the
396 * desired result.
397 */
398 if (compose != 0)
399 {
400 /* And obtain alpha pre-multiplication by composing on black: */
401 memset(&png_ptr->background, 0, (sizeof png_ptr->background));
402 png_ptr->background_gamma = png_ptr->colorspace.gamma; /* just in case */
403 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_FILE;
404 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
405
406 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
407 png_error(png_ptr,
408 "conflicting calls to set alpha mode and background");
409
410 png_ptr->transformations |= PNG_COMPOSE;
411 }
412 }
413
414 # ifdef PNG_FLOATING_POINT_SUPPORTED
415 void PNGAPI
416 png_set_alpha_mode(png_structrp png_ptr, int mode, double output_gamma)
417 {
418 png_set_alpha_mode_fixed(png_ptr, mode, convert_gamma_value(png_ptr,
419 output_gamma));
420 }
421 # endif
422 #endif
423
424 #ifdef PNG_READ_QUANTIZE_SUPPORTED
425 /* Dither file to 8-bit. Supply a palette, the current number
426 * of elements in the palette, the maximum number of elements
427 * allowed, and a histogram if possible. If the current number
428 * of colors is greater than the maximum number, the palette will be
429 * modified to fit in the maximum number. "full_quantize" indicates
430 * whether we need a quantizing cube set up for RGB images, or if we
431 * simply are reducing the number of colors in a paletted image.
432 */
433
434 typedef struct png_dsort_struct
435 {
436 struct png_dsort_struct * next;
437 png_byte left;
438 png_byte right;
439 } png_dsort;
440 typedef png_dsort * png_dsortp;
441 typedef png_dsort * * png_dsortpp;
442
443 void PNGAPI
444 png_set_quantize(png_structrp png_ptr, png_colorp palette,
445 int num_palette, int maximum_colors, png_const_uint_16p histogram,
446 int full_quantize)
447 {
448 png_debug(1, "in png_set_quantize");
449
450 if (png_rtran_ok(png_ptr, 0) == 0)
451 return;
452
453 png_ptr->transformations |= PNG_QUANTIZE;
454
455 if (full_quantize == 0)
456 {
457 int i;
458
459 png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr,
460 (png_uint_32)(num_palette * (sizeof (png_byte))));
461 for (i = 0; i < num_palette; i++)
462 png_ptr->quantize_index[i] = (png_byte)i;
463 }
464
465 if (num_palette > maximum_colors)
466 {
467 if (histogram != NULL)
468 {
469 /* This is easy enough, just throw out the least used colors.
470 * Perhaps not the best solution, but good enough.
471 */
472
473 int i;
474
475 /* Initialize an array to sort colors */
476 png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr,
477 (png_uint_32)(num_palette * (sizeof (png_byte))));
478
479 /* Initialize the quantize_sort array */
480 for (i = 0; i < num_palette; i++)
481 png_ptr->quantize_sort[i] = (png_byte)i;
482
483 /* Find the least used palette entries by starting a
484 * bubble sort, and running it until we have sorted
485 * out enough colors. Note that we don't care about
486 * sorting all the colors, just finding which are
487 * least used.
488 */
489
490 for (i = num_palette - 1; i >= maximum_colors; i--)
491 {
492 int done; /* To stop early if the list is pre-sorted */
493 int j;
494
495 done = 1;
496 for (j = 0; j < i; j++)
497 {
498 if (histogram[png_ptr->quantize_sort[j]]
499 < histogram[png_ptr->quantize_sort[j + 1]])
500 {
501 png_byte t;
502
503 t = png_ptr->quantize_sort[j];
504 png_ptr->quantize_sort[j] = png_ptr->quantize_sort[j + 1];
505 png_ptr->quantize_sort[j + 1] = t;
506 done = 0;
507 }
508 }
509
510 if (done != 0)
511 break;
512 }
513
514 /* Swap the palette around, and set up a table, if necessary */
515 if (full_quantize != 0)
516 {
517 int j = num_palette;
518
519 /* Put all the useful colors within the max, but don't
520 * move the others.
521 */
522 for (i = 0; i < maximum_colors; i++)
523 {
524 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
525 {
526 do
527 j--;
528 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
529
530 palette[i] = palette[j];
531 }
532 }
533 }
534 else
535 {
536 int j = num_palette;
537
538 /* Move all the used colors inside the max limit, and
539 * develop a translation table.
540 */
541 for (i = 0; i < maximum_colors; i++)
542 {
543 /* Only move the colors we need to */
544 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
545 {
546 png_color tmp_color;
547
548 do
549 j--;
550 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
551
552 tmp_color = palette[j];
553 palette[j] = palette[i];
554 palette[i] = tmp_color;
555 /* Indicate where the color went */
556 png_ptr->quantize_index[j] = (png_byte)i;
557 png_ptr->quantize_index[i] = (png_byte)j;
558 }
559 }
560
561 /* Find closest color for those colors we are not using */
562 for (i = 0; i < num_palette; i++)
563 {
564 if ((int)png_ptr->quantize_index[i] >= maximum_colors)
565 {
566 int min_d, k, min_k, d_index;
567
568 /* Find the closest color to one we threw out */
569 d_index = png_ptr->quantize_index[i];
570 min_d = PNG_COLOR_DIST(palette[d_index], palette[0]);
571 for (k = 1, min_k = 0; k < maximum_colors; k++)
572 {
573 int d;
574
575 d = PNG_COLOR_DIST(palette[d_index], palette[k]);
576
577 if (d < min_d)
578 {
579 min_d = d;
580 min_k = k;
581 }
582 }
583 /* Point to closest color */
584 png_ptr->quantize_index[i] = (png_byte)min_k;
585 }
586 }
587 }
588 png_free(png_ptr, png_ptr->quantize_sort);
589 png_ptr->quantize_sort = NULL;
590 }
591 else
592 {
593 /* This is much harder to do simply (and quickly). Perhaps
594 * we need to go through a median cut routine, but those
595 * don't always behave themselves with only a few colors
596 * as input. So we will just find the closest two colors,
597 * and throw out one of them (chosen somewhat randomly).
598 * [We don't understand this at all, so if someone wants to
599 * work on improving it, be our guest - AED, GRP]
600 */
601 int i;
602 int max_d;
603 int num_new_palette;
604 png_dsortp t;
605 png_dsortpp hash;
606
607 t = NULL;
608
609 /* Initialize palette index arrays */
610 png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr,
611 (png_uint_32)(num_palette * (sizeof (png_byte))));
612 png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr,
613 (png_uint_32)(num_palette * (sizeof (png_byte))));
614
615 /* Initialize the sort array */
616 for (i = 0; i < num_palette; i++)
617 {
618 png_ptr->index_to_palette[i] = (png_byte)i;
619 png_ptr->palette_to_index[i] = (png_byte)i;
620 }
621
622 hash = (png_dsortpp)png_calloc(png_ptr, (png_uint_32)(769 *
623 (sizeof (png_dsortp))));
624
625 num_new_palette = num_palette;
626
627 /* Initial wild guess at how far apart the farthest pixel
628 * pair we will be eliminating will be. Larger
629 * numbers mean more areas will be allocated, Smaller
630 * numbers run the risk of not saving enough data, and
631 * having to do this all over again.
632 *
633 * I have not done extensive checking on this number.
634 */
635 max_d = 96;
636
637 while (num_new_palette > maximum_colors)
638 {
639 for (i = 0; i < num_new_palette - 1; i++)
640 {
641 int j;
642
643 for (j = i + 1; j < num_new_palette; j++)
644 {
645 int d;
646
647 d = PNG_COLOR_DIST(palette[i], palette[j]);
648
649 if (d <= max_d)
650 {
651
652 t = (png_dsortp)png_malloc_warn(png_ptr,
653 (png_uint_32)(sizeof (png_dsort)));
654
655 if (t == NULL)
656 break;
657
658 t->next = hash[d];
659 t->left = (png_byte)i;
660 t->right = (png_byte)j;
661 hash[d] = t;
662 }
663 }
664 if (t == NULL)
665 break;
666 }
667
668 if (t != NULL)
669 for (i = 0; i <= max_d; i++)
670 {
671 if (hash[i] != NULL)
672 {
673 png_dsortp p;
674
675 for (p = hash[i]; p; p = p->next)
676 {
677 if ((int)png_ptr->index_to_palette[p->left]
678 < num_new_palette &&
679 (int)png_ptr->index_to_palette[p->right]
680 < num_new_palette)
681 {
682 int j, next_j;
683
684 if (num_new_palette & 0x01)
685 {
686 j = p->left;
687 next_j = p->right;
688 }
689 else
690 {
691 j = p->right;
692 next_j = p->left;
693 }
694
695 num_new_palette--;
696 palette[png_ptr->index_to_palette[j]]
697 = palette[num_new_palette];
698 if (full_quantize == 0)
699 {
700 int k;
701
702 for (k = 0; k < num_palette; k++)
703 {
704 if (png_ptr->quantize_index[k] ==
705 png_ptr->index_to_palette[j])
706 png_ptr->quantize_index[k] =
707 png_ptr->index_to_palette[next_j];
708
709 if ((int)png_ptr->quantize_index[k] ==
710 num_new_palette)
711 png_ptr->quantize_index[k] =
712 png_ptr->index_to_palette[j];
713 }
714 }
715
716 png_ptr->index_to_palette[png_ptr->palette_to_index
717 [num_new_palette]] = png_ptr->index_to_palette[j];
718
719 png_ptr->palette_to_index[png_ptr->index_to_palette[j]]
720 = png_ptr->palette_to_index[num_new_palette];
721
722 png_ptr->index_to_palette[j] =
723 (png_byte)num_new_palette;
724
725 png_ptr->palette_to_index[num_new_palette] =
726 (png_byte)j;
727 }
728 if (num_new_palette <= maximum_colors)
729 break;
730 }
731 if (num_new_palette <= maximum_colors)
732 break;
733 }
734 }
735
736 for (i = 0; i < 769; i++)
737 {
738 if (hash[i] != NULL)
739 {
740 png_dsortp p = hash[i];
741 while (p)
742 {
743 t = p->next;
744 png_free(png_ptr, p);
745 p = t;
746 }
747 }
748 hash[i] = 0;
749 }
750 max_d += 96;
751 }
752 png_free(png_ptr, hash);
753 png_free(png_ptr, png_ptr->palette_to_index);
754 png_free(png_ptr, png_ptr->index_to_palette);
755 png_ptr->palette_to_index = NULL;
756 png_ptr->index_to_palette = NULL;
757 }
758 num_palette = maximum_colors;
759 }
760 if (png_ptr->palette == NULL)
761 {
762 png_ptr->palette = palette;
763 }
764 png_ptr->num_palette = (png_uint_16)num_palette;
765
766 if (full_quantize != 0)
767 {
768 int i;
769 png_bytep distance;
770 int total_bits = PNG_QUANTIZE_RED_BITS + PNG_QUANTIZE_GREEN_BITS +
771 PNG_QUANTIZE_BLUE_BITS;
772 int num_red = (1 << PNG_QUANTIZE_RED_BITS);
773 int num_green = (1 << PNG_QUANTIZE_GREEN_BITS);
774 int num_blue = (1 << PNG_QUANTIZE_BLUE_BITS);
775 png_size_t num_entries = ((png_size_t)1 << total_bits);
776
777 png_ptr->palette_lookup = (png_bytep)png_calloc(png_ptr,
778 (png_uint_32)(num_entries * (sizeof (png_byte))));
779
780 distance = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_entries *
781 (sizeof (png_byte))));
782
783 memset(distance, 0xff, num_entries * (sizeof (png_byte)));
784
785 for (i = 0; i < num_palette; i++)
786 {
787 int ir, ig, ib;
788 int r = (palette[i].red >> (8 - PNG_QUANTIZE_RED_BITS));
789 int g = (palette[i].green >> (8 - PNG_QUANTIZE_GREEN_BITS));
790 int b = (palette[i].blue >> (8 - PNG_QUANTIZE_BLUE_BITS));
791
792 for (ir = 0; ir < num_red; ir++)
793 {
794 /* int dr = abs(ir - r); */
795 int dr = ((ir > r) ? ir - r : r - ir);
796 int index_r = (ir << (PNG_QUANTIZE_BLUE_BITS +
797 PNG_QUANTIZE_GREEN_BITS));
798
799 for (ig = 0; ig < num_green; ig++)
800 {
801 /* int dg = abs(ig - g); */
802 int dg = ((ig > g) ? ig - g : g - ig);
803 int dt = dr + dg;
804 int dm = ((dr > dg) ? dr : dg);
805 int index_g = index_r | (ig << PNG_QUANTIZE_BLUE_BITS);
806
807 for (ib = 0; ib < num_blue; ib++)
808 {
809 int d_index = index_g | ib;
810 /* int db = abs(ib - b); */
811 int db = ((ib > b) ? ib - b : b - ib);
812 int dmax = ((dm > db) ? dm : db);
813 int d = dmax + dt + db;
814
815 if (d < (int)distance[d_index])
816 {
817 distance[d_index] = (png_byte)d;
818 png_ptr->palette_lookup[d_index] = (png_byte)i;
819 }
820 }
821 }
822 }
823 }
824
825 png_free(png_ptr, distance);
826 }
827 }
828 #endif /* READ_QUANTIZE */
829
830 #ifdef PNG_READ_GAMMA_SUPPORTED
831 void PNGFAPI
832 png_set_gamma_fixed(png_structrp png_ptr, png_fixed_point scrn_gamma,
833 png_fixed_point file_gamma)
834 {
835 png_debug(1, "in png_set_gamma_fixed");
836
837 if (png_rtran_ok(png_ptr, 0) == 0)
838 return;
839
840 /* New in libpng-1.5.4 - reserve particular negative values as flags. */
841 scrn_gamma = translate_gamma_flags(png_ptr, scrn_gamma, 1/*screen*/);
842 file_gamma = translate_gamma_flags(png_ptr, file_gamma, 0/*file*/);
843
844 /* Checking the gamma values for being >0 was added in 1.5.4 along with the
845 * premultiplied alpha support; this actually hides an undocumented feature
846 * of the previous implementation which allowed gamma processing to be
847 * disabled in background handling. There is no evidence (so far) that this
848 * was being used; however, png_set_background itself accepted and must still
849 * accept '0' for the gamma value it takes, because it isn't always used.
850 *
851 * Since this is an API change (albeit a very minor one that removes an
852 * undocumented API feature) the following checks were only enabled in
853 * libpng-1.6.0.
854 */
855 if (file_gamma <= 0)
856 png_error(png_ptr, "invalid file gamma in png_set_gamma");
857
858 if (scrn_gamma <= 0)
859 png_error(png_ptr, "invalid screen gamma in png_set_gamma");
860
861 /* Set the gamma values unconditionally - this overrides the value in the PNG
862 * file if a gAMA chunk was present. png_set_alpha_mode provides a
863 * different, easier, way to default the file gamma.
864 */
865 png_ptr->colorspace.gamma = file_gamma;
866 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
867 png_ptr->screen_gamma = scrn_gamma;
868 }
869
870 # ifdef PNG_FLOATING_POINT_SUPPORTED
871 void PNGAPI
872 png_set_gamma(png_structrp png_ptr, double scrn_gamma, double file_gamma)
873 {
874 png_set_gamma_fixed(png_ptr, convert_gamma_value(png_ptr, scrn_gamma),
875 convert_gamma_value(png_ptr, file_gamma));
876 }
877 # endif /* FLOATING_POINT */
878 #endif /* READ_GAMMA */
879
880 #ifdef PNG_READ_EXPAND_SUPPORTED
881 /* Expand paletted images to RGB, expand grayscale images of
882 * less than 8-bit depth to 8-bit depth, and expand tRNS chunks
883 * to alpha channels.
884 */
885 void PNGAPI
886 png_set_expand(png_structrp png_ptr)
887 {
888 png_debug(1, "in png_set_expand");
889
890 if (png_rtran_ok(png_ptr, 0) == 0)
891 return;
892
893 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
894 }
895
896 /* GRR 19990627: the following three functions currently are identical
897 * to png_set_expand(). However, it is entirely reasonable that someone
898 * might wish to expand an indexed image to RGB but *not* expand a single,
899 * fully transparent palette entry to a full alpha channel--perhaps instead
900 * convert tRNS to the grayscale/RGB format (16-bit RGB value), or replace
901 * the transparent color with a particular RGB value, or drop tRNS entirely.
902 * IOW, a future version of the library may make the transformations flag
903 * a bit more fine-grained, with separate bits for each of these three
904 * functions.
905 *
906 * More to the point, these functions make it obvious what libpng will be
907 * doing, whereas "expand" can (and does) mean any number of things.
908 *
909 * GRP 20060307: In libpng-1.2.9, png_set_gray_1_2_4_to_8() was modified
910 * to expand only the sample depth but not to expand the tRNS to alpha
911 * and its name was changed to png_set_expand_gray_1_2_4_to_8().
912 */
913
914 /* Expand paletted images to RGB. */
915 void PNGAPI
916 png_set_palette_to_rgb(png_structrp png_ptr)
917 {
918 png_debug(1, "in png_set_palette_to_rgb");
919
920 if (png_rtran_ok(png_ptr, 0) == 0)
921 return;
922
923 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
924 }
925
926 /* Expand grayscale images of less than 8-bit depth to 8 bits. */
927 void PNGAPI
928 png_set_expand_gray_1_2_4_to_8(png_structrp png_ptr)
929 {
930 png_debug(1, "in png_set_expand_gray_1_2_4_to_8");
931
932 if (png_rtran_ok(png_ptr, 0) == 0)
933 return;
934
935 png_ptr->transformations |= PNG_EXPAND;
936 }
937
938 /* Expand tRNS chunks to alpha channels. */
939 void PNGAPI
940 png_set_tRNS_to_alpha(png_structrp png_ptr)
941 {
942 png_debug(1, "in png_set_tRNS_to_alpha");
943
944 if (png_rtran_ok(png_ptr, 0) == 0)
945 return;
946
947 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
948 }
949 #endif /* READ_EXPAND */
950
951 #ifdef PNG_READ_EXPAND_16_SUPPORTED
952 /* Expand to 16-bit channels, expand the tRNS chunk too (because otherwise
953 * it may not work correctly.)
954 */
955 void PNGAPI
956 png_set_expand_16(png_structrp png_ptr)
957 {
958 png_debug(1, "in png_set_expand_16");
959
960 if (png_rtran_ok(png_ptr, 0) == 0)
961 return;
962
963 png_ptr->transformations |= (PNG_EXPAND_16 | PNG_EXPAND | PNG_EXPAND_tRNS);
964 }
965 #endif
966
967 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
968 void PNGAPI
969 png_set_gray_to_rgb(png_structrp png_ptr)
970 {
971 png_debug(1, "in png_set_gray_to_rgb");
972
973 if (png_rtran_ok(png_ptr, 0) == 0)
974 return;
975
976 /* Because rgb must be 8 bits or more: */
977 png_set_expand_gray_1_2_4_to_8(png_ptr);
978 png_ptr->transformations |= PNG_GRAY_TO_RGB;
979 }
980 #endif
981
982 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
983 void PNGFAPI
984 png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action,
985 png_fixed_point red, png_fixed_point green)
986 {
987 png_debug(1, "in png_set_rgb_to_gray");
988
989 /* Need the IHDR here because of the check on color_type below. */
990 /* TODO: fix this */
991 if (png_rtran_ok(png_ptr, 1) == 0)
992 return;
993
994 switch (error_action)
995 {
996 case PNG_ERROR_ACTION_NONE:
997 png_ptr->transformations |= PNG_RGB_TO_GRAY;
998 break;
999
1000 case PNG_ERROR_ACTION_WARN:
1001 png_ptr->transformations |= PNG_RGB_TO_GRAY_WARN;
1002 break;
1003
1004 case PNG_ERROR_ACTION_ERROR:
1005 png_ptr->transformations |= PNG_RGB_TO_GRAY_ERR;
1006 break;
1007
1008 default:
1009 png_error(png_ptr, "invalid error action to rgb_to_gray");
1010 }
1011
1012 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1013 #ifdef PNG_READ_EXPAND_SUPPORTED
1014 png_ptr->transformations |= PNG_EXPAND;
1015 #else
1016 {
1017 /* Make this an error in 1.6 because otherwise the application may assume
1018 * that it just worked and get a memory overwrite.
1019 */
1020 png_error(png_ptr,
1021 "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED");
1022
1023 /* png_ptr->transformations &= ~PNG_RGB_TO_GRAY; */
1024 }
1025 #endif
1026 {
1027 if (red >= 0 && green >= 0 && red + green <= PNG_FP_1)
1028 {
1029 png_uint_16 red_int, green_int;
1030
1031 /* NOTE: this calculation does not round, but this behavior is retained
1032 * for consistency; the inaccuracy is very small. The code here always
1033 * overwrites the coefficients, regardless of whether they have been
1034 * defaulted or set already.
1035 */
1036 red_int = (png_uint_16)(((png_uint_32)red*32768)/100000);
1037 green_int = (png_uint_16)(((png_uint_32)green*32768)/100000);
1038
1039 png_ptr->rgb_to_gray_red_coeff = red_int;
1040 png_ptr->rgb_to_gray_green_coeff = green_int;
1041 png_ptr->rgb_to_gray_coefficients_set = 1;
1042 }
1043
1044 else
1045 {
1046 if (red >= 0 && green >= 0)
1047 png_app_warning(png_ptr,
1048 "ignoring out of range rgb_to_gray coefficients");
1049
1050 /* Use the defaults, from the cHRM chunk if set, else the historical
1051 * values which are close to the sRGB/HDTV/ITU-Rec 709 values. See
1052 * png_do_rgb_to_gray for more discussion of the values. In this case
1053 * the coefficients are not marked as 'set' and are not overwritten if
1054 * something has already provided a default.
1055 */
1056 if (png_ptr->rgb_to_gray_red_coeff == 0 &&
1057 png_ptr->rgb_to_gray_green_coeff == 0)
1058 {
1059 png_ptr->rgb_to_gray_red_coeff = 6968;
1060 png_ptr->rgb_to_gray_green_coeff = 23434;
1061 /* png_ptr->rgb_to_gray_blue_coeff = 2366; */
1062 }
1063 }
1064 }
1065 }
1066
1067 #ifdef PNG_FLOATING_POINT_SUPPORTED
1068 /* Convert a RGB image to a grayscale of the same width. This allows us,
1069 * for example, to convert a 24 bpp RGB image into an 8 bpp grayscale image.
1070 */
1071
1072 void PNGAPI
1073 png_set_rgb_to_gray(png_structrp png_ptr, int error_action, double red,
1074 double green)
1075 {
1076 png_set_rgb_to_gray_fixed(png_ptr, error_action,
1077 png_fixed(png_ptr, red, "rgb to gray red coefficient"),
1078 png_fixed(png_ptr, green, "rgb to gray green coefficient"));
1079 }
1080 #endif /* FLOATING POINT */
1081
1082 #endif /* RGB_TO_GRAY */
1083
1084 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
1085 defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
1086 void PNGAPI
1087 png_set_read_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr
1088 read_user_transform_fn)
1089 {
1090 png_debug(1, "in png_set_read_user_transform_fn");
1091
1092 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
1093 png_ptr->transformations |= PNG_USER_TRANSFORM;
1094 png_ptr->read_user_transform_fn = read_user_transform_fn;
1095 #endif
1096 }
1097 #endif
1098
1099 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
1100 #ifdef PNG_READ_GAMMA_SUPPORTED
1101 /* In the case of gamma transformations only do transformations on images where
1102 * the [file] gamma and screen_gamma are not close reciprocals, otherwise it
1103 * slows things down slightly, and also needlessly introduces small errors.
1104 */
1105 static int /* PRIVATE */
1106 png_gamma_threshold(png_fixed_point screen_gamma, png_fixed_point file_gamma)
1107 {
1108 /* PNG_GAMMA_THRESHOLD is the threshold for performing gamma
1109 * correction as a difference of the overall transform from 1.0
1110 *
1111 * We want to compare the threshold with s*f - 1, if we get
1112 * overflow here it is because of wacky gamma values so we
1113 * turn on processing anyway.
1114 */
1115 png_fixed_point gtest;
1116 return !png_muldiv(>est, screen_gamma, file_gamma, PNG_FP_1) ||
1117 png_gamma_significant(gtest);
1118 }
1119 #endif
1120
1121 /* Initialize everything needed for the read. This includes modifying
1122 * the palette.
1123 */
1124
1125 /* For the moment 'png_init_palette_transformations' and
1126 * 'png_init_rgb_transformations' only do some flag canceling optimizations.
1127 * The intent is that these two routines should have palette or rgb operations
1128 * extracted from 'png_init_read_transformations'.
1129 */
1130 static void /* PRIVATE */
1131 png_init_palette_transformations(png_structrp png_ptr)
1132 {
1133 /* Called to handle the (input) palette case. In png_do_read_transformations
1134 * the first step is to expand the palette if requested, so this code must
1135 * take care to only make changes that are invariant with respect to the
1136 * palette expansion, or only do them if there is no expansion.
1137 *
1138 * STRIP_ALPHA has already been handled in the caller (by setting num_trans
1139 * to 0.)
1140 */
1141 int input_has_alpha = 0;
1142 int input_has_transparency = 0;
1143
1144 if (png_ptr->num_trans > 0)
1145 {
1146 int i;
1147
1148 /* Ignore if all the entries are opaque (unlikely!) */
1149 for (i=0; i<png_ptr->num_trans; ++i)
1150 {
1151 if (png_ptr->trans_alpha[i] == 255)
1152 continue;
1153 else if (png_ptr->trans_alpha[i] == 0)
1154 input_has_transparency = 1;
1155 else
1156 {
1157 input_has_transparency = 1;
1158 input_has_alpha = 1;
1159 break;
1160 }
1161 }
1162 }
1163
1164 /* If no alpha we can optimize. */
1165 if (input_has_alpha == 0)
1166 {
1167 /* Any alpha means background and associative alpha processing is
1168 * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
1169 * and ENCODE_ALPHA are irrelevant.
1170 */
1171 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1172 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1173
1174 if (input_has_transparency == 0)
1175 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1176 }
1177
1178 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1179 /* png_set_background handling - deals with the complexity of whether the
1180 * background color is in the file format or the screen format in the case
1181 * where an 'expand' will happen.
1182 */
1183
1184 /* The following code cannot be entered in the alpha pre-multiplication case
1185 * because PNG_BACKGROUND_EXPAND is cancelled below.
1186 */
1187 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
1188 (png_ptr->transformations & PNG_EXPAND) != 0)
1189 {
1190 {
1191 png_ptr->background.red =
1192 png_ptr->palette[png_ptr->background.index].red;
1193 png_ptr->background.green =
1194 png_ptr->palette[png_ptr->background.index].green;
1195 png_ptr->background.blue =
1196 png_ptr->palette[png_ptr->background.index].blue;
1197
1198 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1199 if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
1200 {
1201 if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
1202 {
1203 /* Invert the alpha channel (in tRNS) unless the pixels are
1204 * going to be expanded, in which case leave it for later
1205 */
1206 int i, istop = png_ptr->num_trans;
1207
1208 for (i=0; i<istop; i++)
1209 png_ptr->trans_alpha[i] = (png_byte)(255 -
1210 png_ptr->trans_alpha[i]);
1211 }
1212 }
1213 #endif /* READ_INVERT_ALPHA */
1214 }
1215 } /* background expand and (therefore) no alpha association. */
1216 #endif /* READ_EXPAND && READ_BACKGROUND */
1217 }
1218
1219 static void /* PRIVATE */
1220 png_init_rgb_transformations(png_structrp png_ptr)
1221 {
1222 /* Added to libpng-1.5.4: check the color type to determine whether there
1223 * is any alpha or transparency in the image and simply cancel the
1224 * background and alpha mode stuff if there isn't.
1225 */
1226 int input_has_alpha = (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0;
1227 int input_has_transparency = png_ptr->num_trans > 0;
1228
1229 /* If no alpha we can optimize. */
1230 if (input_has_alpha == 0)
1231 {
1232 /* Any alpha means background and associative alpha processing is
1233 * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
1234 * and ENCODE_ALPHA are irrelevant.
1235 */
1236 # ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1237 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1238 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1239 # endif
1240
1241 if (input_has_transparency == 0)
1242 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1243 }
1244
1245 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1246 /* png_set_background handling - deals with the complexity of whether the
1247 * background color is in the file format or the screen format in the case
1248 * where an 'expand' will happen.
1249 */
1250
1251 /* The following code cannot be entered in the alpha pre-multiplication case
1252 * because PNG_BACKGROUND_EXPAND is cancelled below.
1253 */
1254 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
1255 (png_ptr->transformations & PNG_EXPAND) != 0 &&
1256 (png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
1257 /* i.e., GRAY or GRAY_ALPHA */
1258 {
1259 {
1260 /* Expand background and tRNS chunks */
1261 int gray = png_ptr->background.gray;
1262 int trans_gray = png_ptr->trans_color.gray;
1263
1264 switch (png_ptr->bit_depth)
1265 {
1266 case 1:
1267 gray *= 0xff;
1268 trans_gray *= 0xff;
1269 break;
1270
1271 case 2:
1272 gray *= 0x55;
1273 trans_gray *= 0x55;
1274 break;
1275
1276 case 4:
1277 gray *= 0x11;
1278 trans_gray *= 0x11;
1279 break;
1280
1281 default:
1282
1283 case 8:
1284 /* FALL THROUGH (Already 8 bits) */
1285
1286 case 16:
1287 /* Already a full 16 bits */
1288 break;
1289 }
1290
1291 png_ptr->background.red = png_ptr->background.green =
1292 png_ptr->background.blue = (png_uint_16)gray;
1293
1294 if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
1295 {
1296 png_ptr->trans_color.red = png_ptr->trans_color.green =
1297 png_ptr->trans_color.blue = (png_uint_16)trans_gray;
1298 }
1299 }
1300 } /* background expand and (therefore) no alpha association. */
1301 #endif /* READ_EXPAND && READ_BACKGROUND */
1302 }
1303
1304 void /* PRIVATE */
1305 png_init_read_transformations(png_structrp png_ptr)
1306 {
1307 png_debug(1, "in png_init_read_transformations");
1308
1309 /* This internal function is called from png_read_start_row in pngrutil.c
1310 * and it is called before the 'rowbytes' calculation is done, so the code
1311 * in here can change or update the transformations flags.
1312 *
1313 * First do updates that do not depend on the details of the PNG image data
1314 * being processed.
1315 */
1316
1317 #ifdef PNG_READ_GAMMA_SUPPORTED
1318 /* Prior to 1.5.4 these tests were performed from png_set_gamma, 1.5.4 adds
1319 * png_set_alpha_mode and this is another source for a default file gamma so
1320 * the test needs to be performed later - here. In addition prior to 1.5.4
1321 * the tests were repeated for the PALETTE color type here - this is no
1322 * longer necessary (and doesn't seem to have been necessary before.)
1323 */
1324 {
1325 /* The following temporary indicates if overall gamma correction is
1326 * required.
1327 */
1328 int gamma_correction = 0;
1329
1330 if (png_ptr->colorspace.gamma != 0) /* has been set */
1331 {
1332 if (png_ptr->screen_gamma != 0) /* screen set too */
1333 gamma_correction = png_gamma_threshold(png_ptr->colorspace.gamma,
1334 png_ptr->screen_gamma);
1335
1336 else
1337 /* Assume the output matches the input; a long time default behavior
1338 * of libpng, although the standard has nothing to say about this.
1339 */
1340 png_ptr->screen_gamma = png_reciprocal(png_ptr->colorspace.gamma);
1341 }
1342
1343 else if (png_ptr->screen_gamma != 0)
1344 /* The converse - assume the file matches the screen, note that this
1345 * perhaps undesireable default can (from 1.5.4) be changed by calling
1346 * png_set_alpha_mode (even if the alpha handling mode isn't required
1347 * or isn't changed from the default.)
1348 */
1349 png_ptr->colorspace.gamma = png_reciprocal(png_ptr->screen_gamma);
1350
1351 else /* neither are set */
1352 /* Just in case the following prevents any processing - file and screen
1353 * are both assumed to be linear and there is no way to introduce a
1354 * third gamma value other than png_set_background with 'UNIQUE', and,
1355 * prior to 1.5.4
1356 */
1357 png_ptr->screen_gamma = png_ptr->colorspace.gamma = PNG_FP_1;
1358
1359 /* We have a gamma value now. */
1360 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
1361
1362 /* Now turn the gamma transformation on or off as appropriate. Notice
1363 * that PNG_GAMMA just refers to the file->screen correction. Alpha
1364 * composition may independently cause gamma correction because it needs
1365 * linear data (e.g. if the file has a gAMA chunk but the screen gamma
1366 * hasn't been specified.) In any case this flag may get turned off in
1367 * the code immediately below if the transform can be handled outside the
1368 * row loop.
1369 */
1370 if (gamma_correction != 0)
1371 png_ptr->transformations |= PNG_GAMMA;
1372
1373 else
1374 png_ptr->transformations &= ~PNG_GAMMA;
1375 }
1376 #endif
1377
1378 /* Certain transformations have the effect of preventing other
1379 * transformations that happen afterward in png_do_read_transformations;
1380 * resolve the interdependencies here. From the code of
1381 * png_do_read_transformations the order is:
1382 *
1383 * 1) PNG_EXPAND (including PNG_EXPAND_tRNS)
1384 * 2) PNG_STRIP_ALPHA (if no compose)
1385 * 3) PNG_RGB_TO_GRAY
1386 * 4) PNG_GRAY_TO_RGB iff !PNG_BACKGROUND_IS_GRAY
1387 * 5) PNG_COMPOSE
1388 * 6) PNG_GAMMA
1389 * 7) PNG_STRIP_ALPHA (if compose)
1390 * 8) PNG_ENCODE_ALPHA
1391 * 9) PNG_SCALE_16_TO_8
1392 * 10) PNG_16_TO_8
1393 * 11) PNG_QUANTIZE (converts to palette)
1394 * 12) PNG_EXPAND_16
1395 * 13) PNG_GRAY_TO_RGB iff PNG_BACKGROUND_IS_GRAY
1396 * 14) PNG_INVERT_MONO
1397 * 15) PNG_INVERT_ALPHA
1398 * 16) PNG_SHIFT
1399 * 17) PNG_PACK
1400 * 18) PNG_BGR
1401 * 19) PNG_PACKSWAP
1402 * 20) PNG_FILLER (includes PNG_ADD_ALPHA)
1403 * 21) PNG_SWAP_ALPHA
1404 * 22) PNG_SWAP_BYTES
1405 * 23) PNG_USER_TRANSFORM [must be last]
1406 */
1407 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1408 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
1409 (png_ptr->transformations & PNG_COMPOSE) == 0)
1410 {
1411 /* Stripping the alpha channel happens immediately after the 'expand'
1412 * transformations, before all other transformation, so it cancels out
1413 * the alpha handling. It has the side effect negating the effect of
1414 * PNG_EXPAND_tRNS too:
1415 */
1416 png_ptr->transformations &= ~(PNG_BACKGROUND_EXPAND | PNG_ENCODE_ALPHA |
1417 PNG_EXPAND_tRNS);
1418 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1419
1420 /* Kill the tRNS chunk itself too. Prior to 1.5.4 this did not happen
1421 * so transparency information would remain just so long as it wasn't
1422 * expanded. This produces unexpected API changes if the set of things
1423 * that do PNG_EXPAND_tRNS changes (perfectly possible given the
1424 * documentation - which says ask for what you want, accept what you
1425 * get.) This makes the behavior consistent from 1.5.4:
1426 */
1427 png_ptr->num_trans = 0;
1428 }
1429 #endif /* STRIP_ALPHA supported, no COMPOSE */
1430
1431 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1432 /* If the screen gamma is about 1.0 then the OPTIMIZE_ALPHA and ENCODE_ALPHA
1433 * settings will have no effect.
1434 */
1435 if (png_gamma_significant(png_ptr->screen_gamma) == 0)
1436 {
1437 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1438 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1439 }
1440 #endif
1441
1442 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1443 /* Make sure the coefficients for the rgb to gray conversion are set
1444 * appropriately.
1445 */
1446 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
1447 png_colorspace_set_rgb_coefficients(png_ptr);
1448 #endif
1449
1450 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1451 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1452 /* Detect gray background and attempt to enable optimization for
1453 * gray --> RGB case.
1454 *
1455 * Note: if PNG_BACKGROUND_EXPAND is set and color_type is either RGB or
1456 * RGB_ALPHA (in which case need_expand is superfluous anyway), the
1457 * background color might actually be gray yet not be flagged as such.
1458 * This is not a problem for the current code, which uses
1459 * PNG_BACKGROUND_IS_GRAY only to decide when to do the
1460 * png_do_gray_to_rgb() transformation.
1461 *
1462 * TODO: this code needs to be revised to avoid the complexity and
1463 * interdependencies. The color type of the background should be recorded in
1464 * png_set_background, along with the bit depth, then the code has a record
1465 * of exactly what color space the background is currently in.
1466 */
1467 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0)
1468 {
1469 /* PNG_BACKGROUND_EXPAND: the background is in the file color space, so if
1470 * the file was grayscale the background value is gray.
1471 */
1472 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
1473 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1474 }
1475
1476 else if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1477 {
1478 /* PNG_COMPOSE: png_set_background was called with need_expand false,
1479 * so the color is in the color space of the output or png_set_alpha_mode
1480 * was called and the color is black. Ignore RGB_TO_GRAY because that
1481 * happens before GRAY_TO_RGB.
1482 */
1483 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
1484 {
1485 if (png_ptr->background.red == png_ptr->background.green &&
1486 png_ptr->background.red == png_ptr->background.blue)
1487 {
1488 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1489 png_ptr->background.gray = png_ptr->background.red;
1490 }
1491 }
1492 }
1493 #endif /* READ_EXPAND && READ_BACKGROUND */
1494 #endif /* READ_GRAY_TO_RGB */
1495
1496 /* For indexed PNG data (PNG_COLOR_TYPE_PALETTE) many of the transformations
1497 * can be performed directly on the palette, and some (such as rgb to gray)
1498 * can be optimized inside the palette. This is particularly true of the
1499 * composite (background and alpha) stuff, which can be pretty much all done
1500 * in the palette even if the result is expanded to RGB or gray afterward.
1501 *
1502 * NOTE: this is Not Yet Implemented, the code behaves as in 1.5.1 and
1503 * earlier and the palette stuff is actually handled on the first row. This
1504 * leads to the reported bug that the palette returned by png_get_PLTE is not
1505 * updated.
1506 */
1507 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1508 png_init_palette_transformations(png_ptr);
1509
1510 else
1511 png_init_rgb_transformations(png_ptr);
1512
1513 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1514 defined(PNG_READ_EXPAND_16_SUPPORTED)
1515 if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
1516 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
1517 (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
1518 png_ptr->bit_depth != 16)
1519 {
1520 /* TODO: fix this. Because the expand_16 operation is after the compose
1521 * handling the background color must be 8, not 16, bits deep, but the
1522 * application will supply a 16-bit value so reduce it here.
1523 *
1524 * The PNG_BACKGROUND_EXPAND code above does not expand to 16 bits at
1525 * present, so that case is ok (until do_expand_16 is moved.)
1526 *
1527 * NOTE: this discards the low 16 bits of the user supplied background
1528 * color, but until expand_16 works properly there is no choice!
1529 */
1530 # define CHOP(x) (x)=((png_uint_16)PNG_DIV257(x))
1531 CHOP(png_ptr->background.red);
1532 CHOP(png_ptr->background.green);
1533 CHOP(png_ptr->background.blue);
1534 CHOP(png_ptr->background.gray);
1535 # undef CHOP
1536 }
1537 #endif /* READ_BACKGROUND && READ_EXPAND_16 */
1538
1539 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1540 (defined(PNG_READ_SCALE_16_TO_8_SUPPORTED) || \
1541 defined(PNG_READ_STRIP_16_TO_8_SUPPORTED))
1542 if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) != 0 &&
1543 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
1544 (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
1545 png_ptr->bit_depth == 16)
1546 {
1547 /* On the other hand, if a 16-bit file is to be reduced to 8-bits per
1548 * component this will also happen after PNG_COMPOSE and so the background
1549 * color must be pre-expanded here.
1550 *
1551 * TODO: fix this too.
1552 */
1553 png_ptr->background.red = (png_uint_16)(png_ptr->background.red * 257);
1554 png_ptr->background.green =
1555 (png_uint_16)(png_ptr->background.green * 257);
1556 png_ptr->background.blue = (png_uint_16)(png_ptr->background.blue * 257);
1557 png_ptr->background.gray = (png_uint_16)(png_ptr->background.gray * 257);
1558 }
1559 #endif
1560
1561 /* NOTE: below 'PNG_READ_ALPHA_MODE_SUPPORTED' is presumed to also enable the
1562 * background support (see the comments in scripts/pnglibconf.dfa), this
1563 * allows pre-multiplication of the alpha channel to be implemented as
1564 * compositing on black. This is probably sub-optimal and has been done in
1565 * 1.5.4 betas simply to enable external critique and testing (i.e. to
1566 * implement the new API quickly, without lots of internal changes.)
1567 */
1568
1569 #ifdef PNG_READ_GAMMA_SUPPORTED
1570 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1571 /* Includes ALPHA_MODE */
1572 png_ptr->background_1 = png_ptr->background;
1573 # endif
1574
1575 /* This needs to change - in the palette image case a whole set of tables are
1576 * built when it would be quicker to just calculate the correct value for
1577 * each palette entry directly. Also, the test is too tricky - why check
1578 * PNG_RGB_TO_GRAY if PNG_GAMMA is not set? The answer seems to be that
1579 * PNG_GAMMA is cancelled even if the gamma is known? The test excludes the
1580 * PNG_COMPOSE case, so apparently if there is no *overall* gamma correction
1581 * the gamma tables will not be built even if composition is required on a
1582 * gamma encoded value.
1583 *
1584 * In 1.5.4 this is addressed below by an additional check on the individual
1585 * file gamma - if it is not 1.0 both RGB_TO_GRAY and COMPOSE need the
1586 * tables.
1587 */
1588 if ((png_ptr->transformations & PNG_GAMMA) != 0 ||
1589 ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0 &&
1590 (png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
1591 png_gamma_significant(png_ptr->screen_gamma) != 0)) ||
1592 ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
1593 (png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
1594 png_gamma_significant(png_ptr->screen_gamma) != 0
1595 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1596 || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE &&
1597 png_gamma_significant(png_ptr->background_gamma) != 0)
1598 # endif
1599 )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 &&
1600 png_gamma_significant(png_ptr->screen_gamma) != 0))
1601 {
1602 png_build_gamma_table(png_ptr, png_ptr->bit_depth);
1603
1604 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1605 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1606 {
1607 /* Issue a warning about this combination: because RGB_TO_GRAY is
1608 * optimized to do the gamma transform if present yet do_background has
1609 * to do the same thing if both options are set a
1610 * double-gamma-correction happens. This is true in all versions of
1611 * libpng to date.
1612 */
1613 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
1614 png_warning(png_ptr,
1615 "libpng does not support gamma+background+rgb_to_gray");
1616
1617 if ((png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) != 0)
1618 {
1619 /* We don't get to here unless there is a tRNS chunk with non-opaque
1620 * entries - see the checking code at the start of this function.
1621 */
1622 png_color back, back_1;
1623 png_colorp palette = png_ptr->palette;
1624 int num_palette = png_ptr->num_palette;
1625 int i;
1626 if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_FILE)
1627 {
1628
1629 back.red = png_ptr->gamma_table[png_ptr->background.red];
1630 back.green = png_ptr->gamma_table[png_ptr->background.green];
1631 back.blue = png_ptr->gamma_table[png_ptr->background.blue];
1632
1633 back_1.red = png_ptr->gamma_to_1[png_ptr->background.red];
1634 back_1.green = png_ptr->gamma_to_1[png_ptr->background.green];
1635 back_1.blue = png_ptr->gamma_to_1[png_ptr->background.blue];
1636 }
1637 else
1638 {
1639 png_fixed_point g, gs;
1640
1641 switch (png_ptr->background_gamma_type)
1642 {
1643 case PNG_BACKGROUND_GAMMA_SCREEN:
1644 g = (png_ptr->screen_gamma);
1645 gs = PNG_FP_1;
1646 break;
1647
1648 case PNG_BACKGROUND_GAMMA_FILE:
1649 g = png_reciprocal(png_ptr->colorspace.gamma);
1650 gs = png_reciprocal2(png_ptr->colorspace.gamma,
1651 png_ptr->screen_gamma);
1652 break;
1653
1654 case PNG_BACKGROUND_GAMMA_UNIQUE:
1655 g = png_reciprocal(png_ptr->background_gamma);
1656 gs = png_reciprocal2(png_ptr->background_gamma,
1657 png_ptr->screen_gamma);
1658 break;
1659 default:
1660 g = PNG_FP_1; /* back_1 */
1661 gs = PNG_FP_1; /* back */
1662 break;
1663 }
1664
1665 if (png_gamma_significant(gs) != 0)
1666 {
1667 back.red = png_gamma_8bit_correct(png_ptr->background.red,
1668 gs);
1669 back.green = png_gamma_8bit_correct(png_ptr->background.green,
1670 gs);
1671 back.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1672 gs);
1673 }
1674
1675 else
1676 {
1677 back.red = (png_byte)png_ptr->background.red;
1678 back.green = (png_byte)png_ptr->background.green;
1679 back.blue = (png_byte)png_ptr->background.blue;
1680 }
1681
1682 if (png_gamma_significant(g) != 0)
1683 {
1684 back_1.red = png_gamma_8bit_correct(png_ptr->background.red,
1685 g);
1686 back_1.green = png_gamma_8bit_correct(
1687 png_ptr->background.green, g);
1688 back_1.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1689 g);
1690 }
1691
1692 else
1693 {
1694 back_1.red = (png_byte)png_ptr->background.red;
1695 back_1.green = (png_byte)png_ptr->background.green;
1696 back_1.blue = (png_byte)png_ptr->background.blue;
1697 }
1698 }
1699
1700 for (i = 0; i < num_palette; i++)
1701 {
1702 if (i < (int)png_ptr->num_trans &&
1703 png_ptr->trans_alpha[i] != 0xff)
1704 {
1705 if (png_ptr->trans_alpha[i] == 0)
1706 {
1707 palette[i] = back;
1708 }
1709 else /* if (png_ptr->trans_alpha[i] != 0xff) */
1710 {
1711 png_byte v, w;
1712
1713 v = png_ptr->gamma_to_1[palette[i].red];
1714 png_composite(w, v, png_ptr->trans_alpha[i], back_1.red);
1715 palette[i].red = png_ptr->gamma_from_1[w];
1716
1717 v = png_ptr->gamma_to_1[palette[i].green];
1718 png_composite(w, v, png_ptr->trans_alpha[i], back_1.green);
1719 palette[i].green = png_ptr->gamma_from_1[w];
1720
1721 v = png_ptr->gamma_to_1[palette[i].blue];
1722 png_composite(w, v, png_ptr->trans_alpha[i], back_1.blue);
1723 palette[i].blue = png_ptr->gamma_from_1[w];
1724 }
1725 }
1726 else
1727 {
1728 palette[i].red = png_ptr->gamma_table[palette[i].red];
1729 palette[i].green = png_ptr->gamma_table[palette[i].green];
1730 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1731 }
1732 }
1733
1734 /* Prevent the transformations being done again.
1735 *
1736 * NOTE: this is highly dubious; it removes the transformations in
1737 * place. This seems inconsistent with the general treatment of the
1738 * transformations elsewhere.
1739 */
1740 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_GAMMA);
1741 } /* color_type == PNG_COLOR_TYPE_PALETTE */
1742
1743 /* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */
1744 else /* color_type != PNG_COLOR_TYPE_PALETTE */
1745 {
1746 int gs_sig, g_sig;
1747 png_fixed_point g = PNG_FP_1; /* Correction to linear */
1748 png_fixed_point gs = PNG_FP_1; /* Correction to screen */
1749
1750 switch (png_ptr->background_gamma_type)
1751 {
1752 case PNG_BACKGROUND_GAMMA_SCREEN:
1753 g = png_ptr->screen_gamma;
1754 /* gs = PNG_FP_1; */
1755 break;
1756
1757 case PNG_BACKGROUND_GAMMA_FILE:
1758 g = png_reciprocal(png_ptr->colorspace.gamma);
1759 gs = png_reciprocal2(png_ptr->colorspace.gamma,
1760 png_ptr->screen_gamma);
1761 break;
1762
1763 case PNG_BACKGROUND_GAMMA_UNIQUE:
1764 g = png_reciprocal(png_ptr->background_gamma);
1765 gs = png_reciprocal2(png_ptr->background_gamma,
1766 png_ptr->screen_gamma);
1767 break;
1768
1769 default:
1770 png_error(png_ptr, "invalid background gamma type");
1771 }
1772
1773 g_sig = png_gamma_significant(g);
1774 gs_sig = png_gamma_significant(gs);
1775
1776 if (g_sig != 0)
1777 png_ptr->background_1.gray = png_gamma_correct(png_ptr,
1778 png_ptr->background.gray, g);
1779
1780 if (gs_sig != 0)
1781 png_ptr->background.gray = png_gamma_correct(png_ptr,
1782 png_ptr->background.gray, gs);
1783
1784 if ((png_ptr->background.red != png_ptr->background.green) ||
1785 (png_ptr->background.red != png_ptr->background.blue) ||
1786 (png_ptr->background.red != png_ptr->background.gray))
1787 {
1788 /* RGB or RGBA with color background */
1789 if (g_sig != 0)
1790 {
1791 png_ptr->background_1.red = png_gamma_correct(png_ptr,
1792 png_ptr->background.red, g);
1793
1794 png_ptr->background_1.green = png_gamma_correct(png_ptr,
1795 png_ptr->background.green, g);
1796
1797 png_ptr->background_1.blue = png_gamma_correct(png_ptr,
1798 png_ptr->background.blue, g);
1799 }
1800
1801 if (gs_sig != 0)
1802 {
1803 png_ptr->background.red = png_gamma_correct(png_ptr,
1804 png_ptr->background.red, gs);
1805
1806 png_ptr->background.green = png_gamma_correct(png_ptr,
1807 png_ptr->background.green, gs);
1808
1809 png_ptr->background.blue = png_gamma_correct(png_ptr,
1810 png_ptr->background.blue, gs);
1811 }
1812 }
1813
1814 else
1815 {
1816 /* GRAY, GRAY ALPHA, RGB, or RGBA with gray background */
1817 png_ptr->background_1.red = png_ptr->background_1.green
1818 = png_ptr->background_1.blue = png_ptr->background_1.gray;
1819
1820 png_ptr->background.red = png_ptr->background.green
1821 = png_ptr->background.blue = png_ptr->background.gray;
1822 }
1823
1824 /* The background is now in screen gamma: */
1825 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_SCREEN;
1826 } /* color_type != PNG_COLOR_TYPE_PALETTE */
1827 }/* png_ptr->transformations & PNG_BACKGROUND */
1828
1829 else
1830 /* Transformation does not include PNG_BACKGROUND */
1831 #endif /* READ_BACKGROUND */
1832 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE
1833 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1834 /* RGB_TO_GRAY needs to have non-gamma-corrected values! */
1835 && ((png_ptr->transformations & PNG_EXPAND) == 0 ||
1836 (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
1837 #endif
1838 )
1839 {
1840 png_colorp palette = png_ptr->palette;
1841 int num_palette = png_ptr->num_palette;
1842 int i;
1843
1844 /* NOTE: there are other transformations that should probably be in
1845 * here too.
1846 */
1847 for (i = 0; i < num_palette; i++)
1848 {
1849 palette[i].red = png_ptr->gamma_table[palette[i].red];
1850 palette[i].green = png_ptr->gamma_table[palette[i].green];
1851 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1852 }
1853
1854 /* Done the gamma correction. */
1855 png_ptr->transformations &= ~PNG_GAMMA;
1856 } /* color_type == PALETTE && !PNG_BACKGROUND transformation */
1857 }
1858 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1859 else
1860 #endif
1861 #endif /* READ_GAMMA */
1862
1863 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1864 /* No GAMMA transformation (see the hanging else 4 lines above) */
1865 if ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
1866 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1867 {
1868 int i;
1869 int istop = (int)png_ptr->num_trans;
1870 png_color back;
1871 png_colorp palette = png_ptr->palette;
1872
1873 back.red = (png_byte)png_ptr->background.red;
1874 back.green = (png_byte)png_ptr->background.green;
1875 back.blue = (png_byte)png_ptr->background.blue;
1876
1877 for (i = 0; i < istop; i++)
1878 {
1879 if (png_ptr->trans_alpha[i] == 0)
1880 {
1881 palette[i] = back;
1882 }
1883
1884 else if (png_ptr->trans_alpha[i] != 0xff)
1885 {
1886 /* The png_composite() macro is defined in png.h */
1887 png_composite(palette[i].red, palette[i].red,
1888 png_ptr->trans_alpha[i], back.red);
1889
1890 png_composite(palette[i].green, palette[i].green,
1891 png_ptr->trans_alpha[i], back.green);
1892
1893 png_composite(palette[i].blue, palette[i].blue,
1894 png_ptr->trans_alpha[i], back.blue);
1895 }
1896 }
1897
1898 png_ptr->transformations &= ~PNG_COMPOSE;
1899 }
1900 #endif /* READ_BACKGROUND */
1901
1902 #ifdef PNG_READ_SHIFT_SUPPORTED
1903 if ((png_ptr->transformations & PNG_SHIFT) != 0 &&
1904 (png_ptr->transformations & PNG_EXPAND) == 0 &&
1905 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1906 {
1907 int i;
1908 int istop = png_ptr->num_palette;
1909 int shift = 8 - png_ptr->sig_bit.red;
1910
1911 png_ptr->transformations &= ~PNG_SHIFT;
1912
1913 /* significant bits can be in the range 1 to 7 for a meaninful result, if
1914 * the number of significant bits is 0 then no shift is done (this is an
1915 * error condition which is silently ignored.)
1916 */
1917 if (shift > 0 && shift < 8)
1918 for (i=0; i<istop; ++i)
1919 {
1920 int component = png_ptr->palette[i].red;
1921
1922 component >>= shift;
1923 png_ptr->palette[i].red = (png_byte)component;
1924 }
1925
1926 shift = 8 - png_ptr->sig_bit.green;
1927 if (shift > 0 && shift < 8)
1928 for (i=0; i<istop; ++i)
1929 {
1930 int component = png_ptr->palette[i].green;
1931
1932 component >>= shift;
1933 png_ptr->palette[i].green = (png_byte)component;
1934 }
1935
1936 shift = 8 - png_ptr->sig_bit.blue;
1937 if (shift > 0 && shift < 8)
1938 for (i=0; i<istop; ++i)
1939 {
1940 int component = png_ptr->palette[i].blue;
1941
1942 component >>= shift;
1943 png_ptr->palette[i].blue = (png_byte)component;
1944 }
1945 }
1946 #endif /* READ_SHIFT */
1947 }
1948
1949 /* Modify the info structure to reflect the transformations. The
1950 * info should be updated so a PNG file could be written with it,
1951 * assuming the transformations result in valid PNG data.
1952 */
1953 void /* PRIVATE */
1954 png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
1955 {
1956 png_debug(1, "in png_read_transform_info");
1957
1958 #ifdef PNG_READ_EXPAND_SUPPORTED
1959 if ((png_ptr->transformations & PNG_EXPAND) != 0)
1960 {
1961 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1962 {
1963 /* This check must match what actually happens in
1964 * png_do_expand_palette; if it ever checks the tRNS chunk to see if
1965 * it is all opaque we must do the same (at present it does not.)
1966 */
1967 if (png_ptr->num_trans > 0)
1968 info_ptr->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
1969
1970 else
1971 info_ptr->color_type = PNG_COLOR_TYPE_RGB;
1972
1973 info_ptr->bit_depth = 8;
1974 info_ptr->num_trans = 0;
1975
1976 if (png_ptr->palette == NULL)
1977 png_error (png_ptr, "Palette is NULL in indexed image");
1978 }
1979 else
1980 {
1981 if (png_ptr->num_trans != 0)
1982 {
1983 if ((png_ptr->transformations & PNG_EXPAND_tRNS) != 0)
1984 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
1985 }
1986 if (info_ptr->bit_depth < 8)
1987 info_ptr->bit_depth = 8;
1988
1989 info_ptr->num_trans = 0;
1990 }
1991 }
1992 #endif
1993
1994 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
1995 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
1996 /* The following is almost certainly wrong unless the background value is in
1997 * the screen space!
1998 */
1999 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
2000 info_ptr->background = png_ptr->background;
2001 #endif
2002
2003 #ifdef PNG_READ_GAMMA_SUPPORTED
2004 /* The following used to be conditional on PNG_GAMMA (prior to 1.5.4),
2005 * however it seems that the code in png_init_read_transformations, which has
2006 * been called before this from png_read_update_info->png_read_start_row
2007 * sometimes does the gamma transform and cancels the flag.
2008 *
2009 * TODO: this looks wrong; the info_ptr should end up with a gamma equal to
2010 * the screen_gamma value. The following probably results in weirdness if
2011 * the info_ptr is used by the app after the rows have been read.
2012 */
2013 info_ptr->colorspace.gamma = png_ptr->colorspace.gamma;
2014 #endif
2015
2016 if (info_ptr->bit_depth == 16)
2017 {
2018 # ifdef PNG_READ_16BIT_SUPPORTED
2019 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2020 if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0)
2021 info_ptr->bit_depth = 8;
2022 # endif
2023
2024 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2025 if ((png_ptr->transformations & PNG_16_TO_8) != 0)
2026 info_ptr->bit_depth = 8;
2027 # endif
2028
2029 # else
2030 /* No 16-bit support: force chopping 16-bit input down to 8, in this case
2031 * the app program can chose if both APIs are available by setting the
2032 * correct scaling to use.
2033 */
2034 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2035 /* For compatibility with previous versions use the strip method by
2036 * default. This code works because if PNG_SCALE_16_TO_8 is already
2037 * set the code below will do that in preference to the chop.
2038 */
2039 png_ptr->transformations |= PNG_16_TO_8;
2040 info_ptr->bit_depth = 8;
2041 # else
2042
2043 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2044 png_ptr->transformations |= PNG_SCALE_16_TO_8;
2045 info_ptr->bit_depth = 8;
2046 # else
2047
2048 CONFIGURATION ERROR: you must enable at least one 16 to 8 method
2049 # endif
2050 # endif
2051 #endif /* !READ_16BIT */
2052 }
2053
2054 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2055 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
2056 info_ptr->color_type = (png_byte)(info_ptr->color_type |
2057 PNG_COLOR_MASK_COLOR);
2058 #endif
2059
2060 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2061 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
2062 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2063 ~PNG_COLOR_MASK_COLOR);
2064 #endif
2065
2066 #ifdef PNG_READ_QUANTIZE_SUPPORTED
2067 if ((png_ptr->transformations & PNG_QUANTIZE) != 0)
2068 {
2069 if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
2070 (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) &&
2071 png_ptr->palette_lookup != 0 && info_ptr->bit_depth == 8)
2072 {
2073 info_ptr->color_type = PNG_COLOR_TYPE_PALETTE;
2074 }
2075 }
2076 #endif
2077
2078 #ifdef PNG_READ_EXPAND_16_SUPPORTED
2079 if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
2080 info_ptr->bit_depth == 8 &&
2081 info_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
2082 {
2083 info_ptr->bit_depth = 16;
2084 }
2085 #endif
2086
2087 #ifdef PNG_READ_PACK_SUPPORTED
2088 if ((png_ptr->transformations & PNG_PACK) != 0 &&
2089 (info_ptr->bit_depth < 8))
2090 info_ptr->bit_depth = 8;
2091 #endif
2092
2093 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
2094 info_ptr->channels = 1;
2095
2096 else if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
2097 info_ptr->channels = 3;
2098
2099 else
2100 info_ptr->channels = 1;
2101
2102 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
2103 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0)
2104 {
2105 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2106 ~PNG_COLOR_MASK_ALPHA);
2107 info_ptr->num_trans = 0;
2108 }
2109 #endif
2110
2111 if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
2112 info_ptr->channels++;
2113
2114 #ifdef PNG_READ_FILLER_SUPPORTED
2115 /* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */
2116 if ((png_ptr->transformations & PNG_FILLER) != 0 &&
2117 (info_ptr->color_type == PNG_COLOR_TYPE_RGB ||
2118 info_ptr->color_type == PNG_COLOR_TYPE_GRAY))
2119 {
2120 info_ptr->channels++;
2121 /* If adding a true alpha channel not just filler */
2122 if ((png_ptr->transformations & PNG_ADD_ALPHA) != 0)
2123 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
2124 }
2125 #endif
2126
2127 #if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \
2128 defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
2129 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
2130 {
2131 if (png_ptr->user_transform_depth != 0)
2132 info_ptr->bit_depth = png_ptr->user_transform_depth;
2133
2134 if (png_ptr->user_transform_channels != 0)
2135 info_ptr->channels = png_ptr->user_transform_channels;
2136 }
2137 #endif
2138
2139 info_ptr->pixel_depth = (png_byte)(info_ptr->channels *
2140 info_ptr->bit_depth);
2141
2142 info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, info_ptr->width);
2143
2144 /* Adding in 1.5.4: cache the above value in png_struct so that we can later
2145 * check in png_rowbytes that the user buffer won't get overwritten. Note
2146 * that the field is not always set - if png_read_update_info isn't called
2147 * the application has to either not do any transforms or get the calculation
2148 * right itself.
2149 */
2150 png_ptr->info_rowbytes = info_ptr->rowbytes;
2151
2152 #ifndef PNG_READ_EXPAND_SUPPORTED
2153 if (png_ptr != NULL)
2154 return;
2155 #endif
2156 }
2157
2158 #ifdef PNG_READ_PACK_SUPPORTED
2159 /* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
2160 * without changing the actual values. Thus, if you had a row with
2161 * a bit depth of 1, you would end up with bytes that only contained
2162 * the numbers 0 or 1. If you would rather they contain 0 and 255, use
2163 * png_do_shift() after this.
2164 */
2165 static void
2166 png_do_unpack(png_row_infop row_info, png_bytep row)
2167 {
2168 png_debug(1, "in png_do_unpack");
2169
2170 if (row_info->bit_depth < 8)
2171 {
2172 png_uint_32 i;
2173 png_uint_32 row_width=row_info->width;
2174
2175 switch (row_info->bit_depth)
2176 {
2177 case 1:
2178 {
2179 png_bytep sp = row + (png_size_t)((row_width - 1) >> 3);
2180 png_bytep dp = row + (png_size_t)row_width - 1;
2181 png_uint_32 shift = 7 - (int)((row_width + 7) & 0x07);
2182 for (i = 0; i < row_width; i++)
2183 {
2184 *dp = (png_byte)((*sp >> shift) & 0x01);
2185
2186 if (shift == 7)
2187 {
2188 shift = 0;
2189 sp--;
2190 }
2191
2192 else
2193 shift++;
2194
2195 dp--;
2196 }
2197 break;
2198 }
2199
2200 case 2:
2201 {
2202
2203 png_bytep sp = row + (png_size_t)((row_width - 1) >> 2);
2204 png_bytep dp = row + (png_size_t)row_width - 1;
2205 png_uint_32 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
2206 for (i = 0; i < row_width; i++)
2207 {
2208 *dp = (png_byte)((*sp >> shift) & 0x03);
2209
2210 if (shift == 6)
2211 {
2212 shift = 0;
2213 sp--;
2214 }
2215
2216 else
2217 shift += 2;
2218
2219 dp--;
2220 }
2221 break;
2222 }
2223
2224 case 4:
2225 {
2226 png_bytep sp = row + (png_size_t)((row_width - 1) >> 1);
2227 png_bytep dp = row + (png_size_t)row_width - 1;
2228 png_uint_32 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
2229 for (i = 0; i < row_width; i++)
2230 {
2231 *dp = (png_byte)((*sp >> shift) & 0x0f);
2232
2233 if (shift == 4)
2234 {
2235 shift = 0;
2236 sp--;
2237 }
2238
2239 else
2240 shift = 4;
2241
2242 dp--;
2243 }
2244 break;
2245 }
2246
2247 default:
2248 break;
2249 }
2250 row_info->bit_depth = 8;
2251 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2252 row_info->rowbytes = row_width * row_info->channels;
2253 }
2254 }
2255 #endif
2256
2257 #ifdef PNG_READ_SHIFT_SUPPORTED
2258 /* Reverse the effects of png_do_shift. This routine merely shifts the
2259 * pixels back to their significant bits values. Thus, if you have
2260 * a row of bit depth 8, but only 5 are significant, this will shift
2261 * the values back to 0 through 31.
2262 */
2263 static void
2264 png_do_unshift(png_row_infop row_info, png_bytep row,
2265 png_const_color_8p sig_bits)
2266 {
2267 int color_type;
2268
2269 png_debug(1, "in png_do_unshift");
2270
2271 /* The palette case has already been handled in the _init routine. */
2272 color_type = row_info->color_type;
2273
2274 if (color_type != PNG_COLOR_TYPE_PALETTE)
2275 {
2276 int shift[4];
2277 int channels = 0;
2278 int bit_depth = row_info->bit_depth;
2279
2280 if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
2281 {
2282 shift[channels++] = bit_depth - sig_bits->red;
2283 shift[channels++] = bit_depth - sig_bits->green;
2284 shift[channels++] = bit_depth - sig_bits->blue;
2285 }
2286
2287 else
2288 {
2289 shift[channels++] = bit_depth - sig_bits->gray;
2290 }
2291
2292 if ((color_type & PNG_COLOR_MASK_ALPHA) != 0)
2293 {
2294 shift[channels++] = bit_depth - sig_bits->alpha;
2295 }
2296
2297 {
2298 int c, have_shift;
2299
2300 for (c = have_shift = 0; c < channels; ++c)
2301 {
2302 /* A shift of more than the bit depth is an error condition but it
2303 * gets ignored here.
2304 */
2305 if (shift[c] <= 0 || shift[c] >= bit_depth)
2306 shift[c] = 0;
2307
2308 else
2309 have_shift = 1;
2310 }
2311
2312 if (have_shift == 0)
2313 return;
2314 }
2315
2316 switch (bit_depth)
2317 {
2318 default:
2319 /* Must be 1bpp gray: should not be here! */
2320 /* NOTREACHED */
2321 break;
2322
2323 case 2:
2324 /* Must be 2bpp gray */
2325 /* assert(channels == 1 && shift[0] == 1) */
2326 {
2327 png_bytep bp = row;
2328 png_bytep bp_end = bp + row_info->rowbytes;
2329
2330 while (bp < bp_end)
2331 {
2332 int b = (*bp >> 1) & 0x55;
2333 *bp++ = (png_byte)b;
2334 }
2335 break;
2336 }
2337
2338 case 4:
2339 /* Must be 4bpp gray */
2340 /* assert(channels == 1) */
2341 {
2342 png_bytep bp = row;
2343 png_bytep bp_end = bp + row_info->rowbytes;
2344 int gray_shift = shift[0];
2345 int mask = 0xf >> gray_shift;
2346
2347 mask |= mask << 4;
2348
2349 while (bp < bp_end)
2350 {
2351 int b = (*bp >> gray_shift) & mask;
2352 *bp++ = (png_byte)b;
2353 }
2354 break;
2355 }
2356
2357 case 8:
2358 /* Single byte components, G, GA, RGB, RGBA */
2359 {
2360 png_bytep bp = row;
2361 png_bytep bp_end = bp + row_info->rowbytes;
2362 int channel = 0;
2363
2364 while (bp < bp_end)
2365 {
2366 int b = *bp >> shift[channel];
2367 if (++channel >= channels)
2368 channel = 0;
2369 *bp++ = (png_byte)b;
2370 }
2371 break;
2372 }
2373
2374 #ifdef PNG_READ_16BIT_SUPPORTED
2375 case 16:
2376 /* Double byte components, G, GA, RGB, RGBA */
2377 {
2378 png_bytep bp = row;
2379 png_bytep bp_end = bp + row_info->rowbytes;
2380 int channel = 0;
2381
2382 while (bp < bp_end)
2383 {
2384 int value = (bp[0] << 8) + bp[1];
2385
2386 value >>= shift[channel];
2387 if (++channel >= channels)
2388 channel = 0;
2389 *bp++ = (png_byte)(value >> 8);
2390 *bp++ = (png_byte)value;
2391 }
2392 break;
2393 }
2394 #endif
2395 }
2396 }
2397 }
2398 #endif
2399
2400 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2401 /* Scale rows of bit depth 16 down to 8 accurately */
2402 static void
2403 png_do_scale_16_to_8(png_row_infop row_info, png_bytep row)
2404 {
2405 png_debug(1, "in png_do_scale_16_to_8");
2406
2407 if (row_info->bit_depth == 16)
2408 {
2409 png_bytep sp = row; /* source */
2410 png_bytep dp = row; /* destination */
2411 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2412
2413 while (sp < ep)
2414 {
2415 /* The input is an array of 16-bit components, these must be scaled to
2416 * 8 bits each. For a 16-bit value V the required value (from the PNG
2417 * specification) is:
2418 *
2419 * (V * 255) / 65535
2420 *
2421 * This reduces to round(V / 257), or floor((V + 128.5)/257)
2422 *
2423 * Represent V as the two byte value vhi.vlo. Make a guess that the
2424 * result is the top byte of V, vhi, then the correction to this value
2425 * is:
2426 *
2427 * error = floor(((V-vhi.vhi) + 128.5) / 257)
2428 * = floor(((vlo-vhi) + 128.5) / 257)
2429 *
2430 * This can be approximated using integer arithmetic (and a signed
2431 * shift):
2432 *
2433 * error = (vlo-vhi+128) >> 8;
2434 *
2435 * The approximate differs from the exact answer only when (vlo-vhi) is
2436 * 128; it then gives a correction of +1 when the exact correction is
2437 * 0. This gives 128 errors. The exact answer (correct for all 16-bit
2438 * input values) is:
2439 *
2440 * error = (vlo-vhi+128)*65535 >> 24;
2441 *
2442 * An alternative arithmetic calculation which also gives no errors is:
2443 *
2444 * (V * 255 + 32895) >> 16
2445 */
2446
2447 png_int_32 tmp = *sp++; /* must be signed! */
2448 tmp += (((int)*sp++ - tmp + 128) * 65535) >> 24;
2449 *dp++ = (png_byte)tmp;
2450 }
2451
2452 row_info->bit_depth = 8;
2453 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2454 row_info->rowbytes = row_info->width * row_info->channels;
2455 }
2456 }
2457 #endif
2458
2459 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2460 static void
2461 /* Simply discard the low byte. This was the default behavior prior
2462 * to libpng-1.5.4.
2463 */
2464 png_do_chop(png_row_infop row_info, png_bytep row)
2465 {
2466 png_debug(1, "in png_do_chop");
2467
2468 if (row_info->bit_depth == 16)
2469 {
2470 png_bytep sp = row; /* source */
2471 png_bytep dp = row; /* destination */
2472 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2473
2474 while (sp < ep)
2475 {
2476 *dp++ = *sp;
2477 sp += 2; /* skip low byte */
2478 }
2479
2480 row_info->bit_depth = 8;
2481 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2482 row_info->rowbytes = row_info->width * row_info->channels;
2483 }
2484 }
2485 #endif
2486
2487 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
2488 static void
2489 png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
2490 {
2491 png_debug(1, "in png_do_read_swap_alpha");
2492
2493 {
2494 png_uint_32 row_width = row_info->width;
2495 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2496 {
2497 /* This converts from RGBA to ARGB */
2498 if (row_info->bit_depth == 8)
2499 {
2500 png_bytep sp = row + row_info->rowbytes;
2501 png_bytep dp = sp;
2502 png_byte save;
2503 png_uint_32 i;
2504
2505 for (i = 0; i < row_width; i++)
2506 {
2507 save = *(--sp);
2508 *(--dp) = *(--sp);
2509 *(--dp) = *(--sp);
2510 *(--dp) = *(--sp);
2511 *(--dp) = save;
2512 }
2513 }
2514
2515 #ifdef PNG_READ_16BIT_SUPPORTED
2516 /* This converts from RRGGBBAA to AARRGGBB */
2517 else
2518 {
2519 png_bytep sp = row + row_info->rowbytes;
2520 png_bytep dp = sp;
2521 png_byte save[2];
2522 png_uint_32 i;
2523
2524 for (i = 0; i < row_width; i++)
2525 {
2526 save[0] = *(--sp);
2527 save[1] = *(--sp);
2528 *(--dp) = *(--sp);
2529 *(--dp) = *(--sp);
2530 *(--dp) = *(--sp);
2531 *(--dp) = *(--sp);
2532 *(--dp) = *(--sp);
2533 *(--dp) = *(--sp);
2534 *(--dp) = save[0];
2535 *(--dp) = save[1];
2536 }
2537 }
2538 #endif
2539 }
2540
2541 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2542 {
2543 /* This converts from GA to AG */
2544 if (row_info->bit_depth == 8)
2545 {
2546 png_bytep sp = row + row_info->rowbytes;
2547 png_bytep dp = sp;
2548 png_byte save;
2549 png_uint_32 i;
2550
2551 for (i = 0; i < row_width; i++)
2552 {
2553 save = *(--sp);
2554 *(--dp) = *(--sp);
2555 *(--dp) = save;
2556 }
2557 }
2558
2559 #ifdef PNG_READ_16BIT_SUPPORTED
2560 /* This converts from GGAA to AAGG */
2561 else
2562 {
2563 png_bytep sp = row + row_info->rowbytes;
2564 png_bytep dp = sp;
2565 png_byte save[2];
2566 png_uint_32 i;
2567
2568 for (i = 0; i < row_width; i++)
2569 {
2570 save[0] = *(--sp);
2571 save[1] = *(--sp);
2572 *(--dp) = *(--sp);
2573 *(--dp) = *(--sp);
2574 *(--dp) = save[0];
2575 *(--dp) = save[1];
2576 }
2577 }
2578 #endif
2579 }
2580 }
2581 }
2582 #endif
2583
2584 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
2585 static void
2586 png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
2587 {
2588 png_uint_32 row_width;
2589 png_debug(1, "in png_do_read_invert_alpha");
2590
2591 row_width = row_info->width;
2592 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2593 {
2594 if (row_info->bit_depth == 8)
2595 {
2596 /* This inverts the alpha channel in RGBA */
2597 png_bytep sp = row + row_info->rowbytes;
2598 png_bytep dp = sp;
2599 png_uint_32 i;
2600
2601 for (i = 0; i < row_width; i++)
2602 {
2603 *(--dp) = (png_byte)(255 - *(--sp));
2604
2605 /* This does nothing:
2606 *(--dp) = *(--sp);
2607 *(--dp) = *(--sp);
2608 *(--dp) = *(--sp);
2609 We can replace it with:
2610 */
2611 sp-=3;
2612 dp=sp;
2613 }
2614 }
2615
2616 #ifdef PNG_READ_16BIT_SUPPORTED
2617 /* This inverts the alpha channel in RRGGBBAA */
2618 else
2619 {
2620 png_bytep sp = row + row_info->rowbytes;
2621 png_bytep dp = sp;
2622 png_uint_32 i;
2623
2624 for (i = 0; i < row_width; i++)
2625 {
2626 *(--dp) = (png_byte)(255 - *(--sp));
2627 *(--dp) = (png_byte)(255 - *(--sp));
2628
2629 /* This does nothing:
2630 *(--dp) = *(--sp);
2631 *(--dp) = *(--sp);
2632 *(--dp) = *(--sp);
2633 *(--dp) = *(--sp);
2634 *(--dp) = *(--sp);
2635 *(--dp) = *(--sp);
2636 We can replace it with:
2637 */
2638 sp-=6;
2639 dp=sp;
2640 }
2641 }
2642 #endif
2643 }
2644 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2645 {
2646 if (row_info->bit_depth == 8)
2647 {
2648 /* This inverts the alpha channel in GA */
2649 png_bytep sp = row + row_info->rowbytes;
2650 png_bytep dp = sp;
2651 png_uint_32 i;
2652
2653 for (i = 0; i < row_width; i++)
2654 {
2655 *(--dp) = (png_byte)(255 - *(--sp));
2656 *(--dp) = *(--sp);
2657 }
2658 }
2659
2660 #ifdef PNG_READ_16BIT_SUPPORTED
2661 else
2662 {
2663 /* This inverts the alpha channel in GGAA */
2664 png_bytep sp = row + row_info->rowbytes;
2665 png_bytep dp = sp;
2666 png_uint_32 i;
2667
2668 for (i = 0; i < row_width; i++)
2669 {
2670 *(--dp) = (png_byte)(255 - *(--sp));
2671 *(--dp) = (png_byte)(255 - *(--sp));
2672 /*
2673 *(--dp) = *(--sp);
2674 *(--dp) = *(--sp);
2675 */
2676 sp-=2;
2677 dp=sp;
2678 }
2679 }
2680 #endif
2681 }
2682 }
2683 #endif
2684
2685 #ifdef PNG_READ_FILLER_SUPPORTED
2686 /* Add filler channel if we have RGB color */
2687 static void
2688 png_do_read_filler(png_row_infop row_info, png_bytep row,
2689 png_uint_32 filler, png_uint_32 flags)
2690 {
2691 png_uint_32 i;
2692 png_uint_32 row_width = row_info->width;
2693
2694 #ifdef PNG_READ_16BIT_SUPPORTED
2695 png_byte hi_filler = (png_byte)(filler>>8);
2696 #endif
2697 png_byte lo_filler = (png_byte)filler;
2698
2699 png_debug(1, "in png_do_read_filler");
2700
2701 if (
2702 row_info->color_type == PNG_COLOR_TYPE_GRAY)
2703 {
2704 if (row_info->bit_depth == 8)
2705 {
2706 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2707 {
2708 /* This changes the data from G to GX */
2709 png_bytep sp = row + (png_size_t)row_width;
2710 png_bytep dp = sp + (png_size_t)row_width;
2711 for (i = 1; i < row_width; i++)
2712 {
2713 *(--dp) = lo_filler;
2714 *(--dp) = *(--sp);
2715 }
2716 *(--dp) = lo_filler;
2717 row_info->channels = 2;
2718 row_info->pixel_depth = 16;
2719 row_info->rowbytes = row_width * 2;
2720 }
2721
2722 else
2723 {
2724 /* This changes the data from G to XG */
2725 png_bytep sp = row + (png_size_t)row_width;
2726 png_bytep dp = sp + (png_size_t)row_width;
2727 for (i = 0; i < row_width; i++)
2728 {
2729 *(--dp) = *(--sp);
2730 *(--dp) = lo_filler;
2731 }
2732 row_info->channels = 2;
2733 row_info->pixel_depth = 16;
2734 row_info->rowbytes = row_width * 2;
2735 }
2736 }
2737
2738 #ifdef PNG_READ_16BIT_SUPPORTED
2739 else if (row_info->bit_depth == 16)
2740 {
2741 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2742 {
2743 /* This changes the data from GG to GGXX */
2744 png_bytep sp = row + (png_size_t)row_width * 2;
2745 png_bytep dp = sp + (png_size_t)row_width * 2;
2746 for (i = 1; i < row_width; i++)
2747 {
2748 *(--dp) = lo_filler;
2749 *(--dp) = hi_filler;
2750 *(--dp) = *(--sp);
2751 *(--dp) = *(--sp);
2752 }
2753 *(--dp) = lo_filler;
2754 *(--dp) = hi_filler;
2755 row_info->channels = 2;
2756 row_info->pixel_depth = 32;
2757 row_info->rowbytes = row_width * 4;
2758 }
2759
2760 else
2761 {
2762 /* This changes the data from GG to XXGG */
2763 png_bytep sp = row + (png_size_t)row_width * 2;
2764 png_bytep dp = sp + (png_size_t)row_width * 2;
2765 for (i = 0; i < row_width; i++)
2766 {
2767 *(--dp) = *(--sp);
2768 *(--dp) = *(--sp);
2769 *(--dp) = lo_filler;
2770 *(--dp) = hi_filler;
2771 }
2772 row_info->channels = 2;
2773 row_info->pixel_depth = 32;
2774 row_info->rowbytes = row_width * 4;
2775 }
2776 }
2777 #endif
2778 } /* COLOR_TYPE == GRAY */
2779 else if (row_info->color_type == PNG_COLOR_TYPE_RGB)
2780 {
2781 if (row_info->bit_depth == 8)
2782 {
2783 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2784 {
2785 /* This changes the data from RGB to RGBX */
2786 png_bytep sp = row + (png_size_t)row_width * 3;
2787 png_bytep dp = sp + (png_size_t)row_width;
2788 for (i = 1; i < row_width; i++)
2789 {
2790 *(--dp) = lo_filler;
2791 *(--dp) = *(--sp);
2792 *(--dp) = *(--sp);
2793 *(--dp) = *(--sp);
2794 }
2795 *(--dp) = lo_filler;
2796 row_info->channels = 4;
2797 row_info->pixel_depth = 32;
2798 row_info->rowbytes = row_width * 4;
2799 }
2800
2801 else
2802 {
2803 /* This changes the data from RGB to XRGB */
2804 png_bytep sp = row + (png_size_t)row_width * 3;
2805 png_bytep dp = sp + (png_size_t)row_width;
2806 for (i = 0; i < row_width; i++)
2807 {
2808 *(--dp) = *(--sp);
2809 *(--dp) = *(--sp);
2810 *(--dp) = *(--sp);
2811 *(--dp) = lo_filler;
2812 }
2813 row_info->channels = 4;
2814 row_info->pixel_depth = 32;
2815 row_info->rowbytes = row_width * 4;
2816 }
2817 }
2818
2819 #ifdef PNG_READ_16BIT_SUPPORTED
2820 else if (row_info->bit_depth == 16)
2821 {
2822 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2823 {
2824 /* This changes the data from RRGGBB to RRGGBBXX */
2825 png_bytep sp = row + (png_size_t)row_width * 6;
2826 png_bytep dp = sp + (png_size_t)row_width * 2;
2827 for (i = 1; i < row_width; i++)
2828 {
2829 *(--dp) = lo_filler;
2830 *(--dp) = hi_filler;
2831 *(--dp) = *(--sp);
2832 *(--dp) = *(--sp);
2833 *(--dp) = *(--sp);
2834 *(--dp) = *(--sp);
2835 *(--dp) = *(--sp);
2836 *(--dp) = *(--sp);
2837 }
2838 *(--dp) = lo_filler;
2839 *(--dp) = hi_filler;
2840 row_info->channels = 4;
2841 row_info->pixel_depth = 64;
2842 row_info->rowbytes = row_width * 8;
2843 }
2844
2845 else
2846 {
2847 /* This changes the data from RRGGBB to XXRRGGBB */
2848 png_bytep sp = row + (png_size_t)row_width * 6;
2849 png_bytep dp = sp + (png_size_t)row_width * 2;
2850 for (i = 0; i < row_width; i++)
2851 {
2852 *(--dp) = *(--sp);
2853 *(--dp) = *(--sp);
2854 *(--dp) = *(--sp);
2855 *(--dp) = *(--sp);
2856 *(--dp) = *(--sp);
2857 *(--dp) = *(--sp);
2858 *(--dp) = lo_filler;
2859 *(--dp) = hi_filler;
2860 }
2861
2862 row_info->channels = 4;
2863 row_info->pixel_depth = 64;
2864 row_info->rowbytes = row_width * 8;
2865 }
2866 }
2867 #endif
2868 } /* COLOR_TYPE == RGB */
2869 }
2870 #endif
2871
2872 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2873 /* Expand grayscale files to RGB, with or without alpha */
2874 static void
2875 png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
2876 {
2877 png_uint_32 i;
2878 png_uint_32 row_width = row_info->width;
2879
2880 png_debug(1, "in png_do_gray_to_rgb");
2881
2882 if (row_info->bit_depth >= 8 &&
2883 (row_info->color_type & PNG_COLOR_MASK_COLOR) == 0)
2884 {
2885 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
2886 {
2887 if (row_info->bit_depth == 8)
2888 {
2889 /* This changes G to RGB */
2890 png_bytep sp = row + (png_size_t)row_width - 1;
2891 png_bytep dp = sp + (png_size_t)row_width * 2;
2892 for (i = 0; i < row_width; i++)
2893 {
2894 *(dp--) = *sp;
2895 *(dp--) = *sp;
2896 *(dp--) = *(sp--);
2897 }
2898 }
2899
2900 else
2901 {
2902 /* This changes GG to RRGGBB */
2903 png_bytep sp = row + (png_size_t)row_width * 2 - 1;
2904 png_bytep dp = sp + (png_size_t)row_width * 4;
2905 for (i = 0; i < row_width; i++)
2906 {
2907 *(dp--) = *sp;
2908 *(dp--) = *(sp - 1);
2909 *(dp--) = *sp;
2910 *(dp--) = *(sp - 1);
2911 *(dp--) = *(sp--);
2912 *(dp--) = *(sp--);
2913 }
2914 }
2915 }
2916
2917 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2918 {
2919 if (row_info->bit_depth == 8)
2920 {
2921 /* This changes GA to RGBA */
2922 png_bytep sp = row + (png_size_t)row_width * 2 - 1;
2923 png_bytep dp = sp + (png_size_t)row_width * 2;
2924 for (i = 0; i < row_width; i++)
2925 {
2926 *(dp--) = *(sp--);
2927 *(dp--) = *sp;
2928 *(dp--) = *sp;
2929 *(dp--) = *(sp--);
2930 }
2931 }
2932
2933 else
2934 {
2935 /* This changes GGAA to RRGGBBAA */
2936 png_bytep sp = row + (png_size_t)row_width * 4 - 1;
2937 png_bytep dp = sp + (png_size_t)row_width * 4;
2938 for (i = 0; i < row_width; i++)
2939 {
2940 *(dp--) = *(sp--);
2941 *(dp--) = *(sp--);
2942 *(dp--) = *sp;
2943 *(dp--) = *(sp - 1);
2944 *(dp--) = *sp;
2945 *(dp--) = *(sp - 1);
2946 *(dp--) = *(sp--);
2947 *(dp--) = *(sp--);
2948 }
2949 }
2950 }
2951 row_info->channels = (png_byte)(row_info->channels + 2);
2952 row_info->color_type |= PNG_COLOR_MASK_COLOR;
2953 row_info->pixel_depth = (png_byte)(row_info->channels *
2954 row_info->bit_depth);
2955 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
2956 }
2957 }
2958 #endif
2959
2960 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2961 /* Reduce RGB files to grayscale, with or without alpha
2962 * using the equation given in Poynton's ColorFAQ of 1998-01-04 at
2963 * <http://www.inforamp.net/~poynton/> (THIS LINK IS DEAD June 2008 but
2964 * versions dated 1998 through November 2002 have been archived at
2965 * http://web.archive.org/web/20000816232553/http://www.inforamp.net/
2966 * ~poynton/notes/colour_and_gamma/ColorFAQ.txt )
2967 * Charles Poynton poynton at poynton.com
2968 *
2969 * Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
2970 *
2971 * which can be expressed with integers as
2972 *
2973 * Y = (6969 * R + 23434 * G + 2365 * B)/32768
2974 *
2975 * Poynton's current link (as of January 2003 through July 2011):
2976 * <http://www.poynton.com/notes/colour_and_gamma/>
2977 * has changed the numbers slightly:
2978 *
2979 * Y = 0.2126*R + 0.7152*G + 0.0722*B
2980 *
2981 * which can be expressed with integers as
2982 *
2983 * Y = (6966 * R + 23436 * G + 2366 * B)/32768
2984 *
2985 * Historically, however, libpng uses numbers derived from the ITU-R Rec 709
2986 * end point chromaticities and the D65 white point. Depending on the
2987 * precision used for the D65 white point this produces a variety of different
2988 * numbers, however if the four decimal place value used in ITU-R Rec 709 is
2989 * used (0.3127,0.3290) the Y calculation would be:
2990 *
2991 * Y = (6968 * R + 23435 * G + 2366 * B)/32768
2992 *
2993 * While this is correct the rounding results in an overflow for white, because
2994 * the sum of the rounded coefficients is 32769, not 32768. Consequently
2995 * libpng uses, instead, the closest non-overflowing approximation:
2996 *
2997 * Y = (6968 * R + 23434 * G + 2366 * B)/32768
2998 *
2999 * Starting with libpng-1.5.5, if the image being converted has a cHRM chunk
3000 * (including an sRGB chunk) then the chromaticities are used to calculate the
3001 * coefficients. See the chunk handling in pngrutil.c for more information.
3002 *
3003 * In all cases the calculation is to be done in a linear colorspace. If no
3004 * gamma information is available to correct the encoding of the original RGB
3005 * values this results in an implicit assumption that the original PNG RGB
3006 * values were linear.
3007 *
3008 * Other integer coefficents can be used via png_set_rgb_to_gray(). Because
3009 * the API takes just red and green coefficients the blue coefficient is
3010 * calculated to make the sum 32768. This will result in different rounding
3011 * to that used above.
3012 */
3013 static int
3014 png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
3015
3016 {
3017 int rgb_error = 0;
3018
3019 png_debug(1, "in png_do_rgb_to_gray");
3020
3021 if ((row_info->color_type & PNG_COLOR_MASK_PALETTE) == 0 &&
3022 (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
3023 {
3024 PNG_CONST png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff;
3025 PNG_CONST png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff;
3026 PNG_CONST png_uint_32 bc = 32768 - rc - gc;
3027 PNG_CONST png_uint_32 row_width = row_info->width;
3028 PNG_CONST int have_alpha =
3029 (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0;
3030
3031 if (row_info->bit_depth == 8)
3032 {
3033 #ifdef PNG_READ_GAMMA_SUPPORTED
3034 /* Notice that gamma to/from 1 are not necessarily inverses (if
3035 * there is an overall gamma correction). Prior to 1.5.5 this code
3036 * checked the linearized values for equality; this doesn't match
3037 * the documentation, the original values must be checked.
3038 */
3039 if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL)
3040 {
3041 png_bytep sp = row;
3042 png_bytep dp = row;
3043 png_uint_32 i;
3044
3045 for (i = 0; i < row_width; i++)
3046 {
3047 png_byte red = *(sp++);
3048 png_byte green = *(sp++);
3049 png_byte blue = *(sp++);
3050
3051 if (red != green || red != blue)
3052 {
3053 red = png_ptr->gamma_to_1[red];
3054 green = png_ptr->gamma_to_1[green];
3055 blue = png_ptr->gamma_to_1[blue];
3056
3057 rgb_error |= 1;
3058 *(dp++) = png_ptr->gamma_from_1[
3059 (rc*red + gc*green + bc*blue + 16384)>>15];
3060 }
3061
3062 else
3063 {
3064 /* If there is no overall correction the table will not be
3065 * set.
3066 */
3067 if (png_ptr->gamma_table != NULL)
3068 red = png_ptr->gamma_table[red];
3069
3070 *(dp++) = red;
3071 }
3072
3073 if (have_alpha != 0)
3074 *(dp++) = *(sp++);
3075 }
3076 }
3077 else
3078 #endif
3079 {
3080 png_bytep sp = row;
3081 png_bytep dp = row;
3082 png_uint_32 i;
3083
3084 for (i = 0; i < row_width; i++)
3085 {
3086 png_byte red = *(sp++);
3087 png_byte green = *(sp++);
3088 png_byte blue = *(sp++);
3089
3090 if (red != green || red != blue)
3091 {
3092 rgb_error |= 1;
3093 /* NOTE: this is the historical approach which simply
3094 * truncates the results.
3095 */
3096 *(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15);
3097 }
3098
3099 else
3100 *(dp++) = red;
3101
3102 if (have_alpha != 0)
3103 *(dp++) = *(sp++);
3104 }
3105 }
3106 }
3107
3108 else /* RGB bit_depth == 16 */
3109 {
3110 #ifdef PNG_READ_GAMMA_SUPPORTED
3111 if (png_ptr->gamma_16_to_1 != NULL && png_ptr->gamma_16_from_1 != NULL)
3112 {
3113 png_bytep sp = row;
3114 png_bytep dp = row;
3115 png_uint_32 i;
3116
3117 for (i = 0; i < row_width; i++)
3118 {
3119 png_uint_16 red, green, blue, w;
3120 png_byte hi,lo;
3121
3122 hi=*(sp)++; lo=*(sp)++; red = (png_uint_16)((hi << 8) | (lo));
3123 hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo));
3124 hi=*(sp)++; lo=*(sp)++; blue = (png_uint_16)((hi << 8) | (lo));
3125
3126 if (red == green && red == blue)
3127 {
3128 if (png_ptr->gamma_16_table != NULL)
3129 w = png_ptr->gamma_16_table[(red & 0xff)
3130 >> png_ptr->gamma_shift][red >> 8];
3131
3132 else
3133 w = red;
3134 }
3135
3136 else
3137 {
3138 png_uint_16 red_1 = png_ptr->gamma_16_to_1[(red & 0xff)
3139 >> png_ptr->gamma_shift][red>>8];
3140 png_uint_16 green_1 =
3141 png_ptr->gamma_16_to_1[(green & 0xff) >>
3142 png_ptr->gamma_shift][green>>8];
3143 png_uint_16 blue_1 = png_ptr->gamma_16_to_1[(blue & 0xff)
3144 >> png_ptr->gamma_shift][blue>>8];
3145 png_uint_16 gray16 = (png_uint_16)((rc*red_1 + gc*green_1
3146 + bc*blue_1 + 16384)>>15);
3147 w = png_ptr->gamma_16_from_1[(gray16 & 0xff) >>
3148 png_ptr->gamma_shift][gray16 >> 8];
3149 rgb_error |= 1;
3150 }
3151
3152 *(dp++) = (png_byte)((w>>8) & 0xff);
3153 *(dp++) = (png_byte)(w & 0xff);
3154
3155 if (have_alpha != 0)
3156 {
3157 *(dp++) = *(sp++);
3158 *(dp++) = *(sp++);
3159 }
3160 }
3161 }
3162 else
3163 #endif
3164 {
3165 png_bytep sp = row;
3166 png_bytep dp = row;
3167 png_uint_32 i;
3168
3169 for (i = 0; i < row_width; i++)
3170 {
3171 png_uint_16 red, green, blue, gray16;
3172 png_byte hi,lo;
3173
3174 hi=*(sp)++; lo=*(sp)++; red = (png_uint_16)((hi << 8) | (lo));
3175 hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo));
3176 hi=*(sp)++; lo=*(sp)++; blue = (png_uint_16)((hi << 8) | (lo));
3177
3178 if (red != green || red != blue)
3179 rgb_error |= 1;
3180
3181 /* From 1.5.5 in the 16-bit case do the accurate conversion even
3182 * in the 'fast' case - this is because this is where the code
3183 * ends up when handling linear 16-bit data.
3184 */
3185 gray16 = (png_uint_16)((rc*red + gc*green + bc*blue + 16384) >>
3186 15);
3187 *(dp++) = (png_byte)((gray16 >> 8) & 0xff);
3188 *(dp++) = (png_byte)(gray16 & 0xff);
3189
3190 if (have_alpha != 0)
3191 {
3192 *(dp++) = *(sp++);
3193 *(dp++) = *(sp++);
3194 }
3195 }
3196 }
3197 }
3198
3199 row_info->channels = (png_byte)(row_info->channels - 2);
3200 row_info->color_type = (png_byte)(row_info->color_type &
3201 ~PNG_COLOR_MASK_COLOR);
3202 row_info->pixel_depth = (png_byte)(row_info->channels *
3203 row_info->bit_depth);
3204 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
3205 }
3206 return rgb_error;
3207 }
3208 #endif
3209
3210 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
3211 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
3212 /* Replace any alpha or transparency with the supplied background color.
3213 * "background" is already in the screen gamma, while "background_1" is
3214 * at a gamma of 1.0. Paletted files have already been taken care of.
3215 */
3216 static void
3217 png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
3218 {
3219 #ifdef PNG_READ_GAMMA_SUPPORTED
3220 png_const_bytep gamma_table = png_ptr->gamma_table;
3221 png_const_bytep gamma_from_1 = png_ptr->gamma_from_1;
3222 png_const_bytep gamma_to_1 = png_ptr->gamma_to_1;
3223 png_const_uint_16pp gamma_16 = png_ptr->gamma_16_table;
3224 png_const_uint_16pp gamma_16_from_1 = png_ptr->gamma_16_from_1;
3225 png_const_uint_16pp gamma_16_to_1 = png_ptr->gamma_16_to_1;
3226 int gamma_shift = png_ptr->gamma_shift;
3227 int optimize = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0;
3228 #endif
3229
3230 png_bytep sp;
3231 png_uint_32 i;
3232 png_uint_32 row_width = row_info->width;
3233 int shift;
3234
3235 png_debug(1, "in png_do_compose");
3236
3237 {
3238 switch (row_info->color_type)
3239 {
3240 case PNG_COLOR_TYPE_GRAY:
3241 {
3242 switch (row_info->bit_depth)
3243 {
3244 case 1:
3245 {
3246 sp = row;
3247 shift = 7;
3248 for (i = 0; i < row_width; i++)
3249 {
3250 if ((png_uint_16)((*sp >> shift) & 0x01)
3251 == png_ptr->trans_color.gray)
3252 {
3253 unsigned int tmp = *sp & (0x7f7f >> (7 - shift));
3254 tmp |= png_ptr->background.gray << shift;
3255 *sp = (png_byte)(tmp & 0xff);
3256 }
3257
3258 if (shift == 0)
3259 {
3260 shift = 7;
3261 sp++;
3262 }
3263
3264 else
3265 shift--;
3266 }
3267 break;
3268 }
3269
3270 case 2:
3271 {
3272 #ifdef PNG_READ_GAMMA_SUPPORTED
3273 if (gamma_table != NULL)
3274 {
3275 sp = row;
3276 shift = 6;
3277 for (i = 0; i < row_width; i++)
3278 {
3279 if ((png_uint_16)((*sp >> shift) & 0x03)
3280 == png_ptr->trans_color.gray)
3281 {
3282 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3283 tmp |= png_ptr->background.gray << shift;
3284 *sp = (png_byte)(tmp & 0xff);
3285 }
3286
3287 else
3288 {
3289 unsigned int p = (*sp >> shift) & 0x03;
3290 unsigned int g = (gamma_table [p | (p << 2) |
3291 (p << 4) | (p << 6)] >> 6) & 0x03;
3292 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3293 tmp |= g << shift;
3294 *sp = (png_byte)(tmp & 0xff);
3295 }
3296
3297 if (shift == 0)
3298 {
3299 shift = 6;
3300 sp++;
3301 }
3302
3303 else
3304 shift -= 2;
3305 }
3306 }
3307
3308 else
3309 #endif
3310 {
3311 sp = row;
3312 shift = 6;
3313 for (i = 0; i < row_width; i++)
3314 {
3315 if ((png_uint_16)((*sp >> shift) & 0x03)
3316 == png_ptr->trans_color.gray)
3317 {
3318 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3319 tmp |= png_ptr->background.gray << shift;
3320 *sp = (png_byte)(tmp & 0xff);
3321 }
3322
3323 if (shift == 0)
3324 {
3325 shift = 6;
3326 sp++;
3327 }
3328
3329 else
3330 shift -= 2;
3331 }
3332 }
3333 break;
3334 }
3335
3336 case 4:
3337 {
3338 #ifdef PNG_READ_GAMMA_SUPPORTED
3339 if (gamma_table != NULL)
3340 {
3341 sp = row;
3342 shift = 4;
3343 for (i = 0; i < row_width; i++)
3344 {
3345 if ((png_uint_16)((*sp >> shift) & 0x0f)
3346 == png_ptr->trans_color.gray)
3347 {
3348 unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
3349 tmp |= png_ptr->background.gray << shift;
3350 *sp = (png_byte)(tmp & 0xff);
3351 }
3352
3353 else
3354 {
3355 unsigned int p = (*sp >> shift) & 0x0f;
3356 unsigned int g = (gamma_table[p | (p << 4)] >> 4) &
3357 0x0f;
3358 unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
3359 tmp |= g << shift;
3360 *sp = (png_byte)(tmp & 0xff);
3361 }
3362
3363 if (shift == 0)
3364 {
3365 shift = 4;
3366 sp++;
3367 }
3368
3369 else
3370 shift -= 4;
3371 }
3372 }
3373
3374 else
3375 #endif
3376 {
3377 sp = row;
3378 shift = 4;
3379 for (i = 0; i < row_width; i++)
3380 {
3381 if ((png_uint_16)((*sp >> shift) & 0x0f)
3382 == png_ptr->trans_color.gray)
3383 {
3384 unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
3385 tmp |= png_ptr->background.gray << shift;
3386 *sp = (png_byte)(tmp & 0xff);
3387 }
3388
3389 if (shift == 0)
3390 {
3391 shift = 4;
3392 sp++;
3393 }
3394
3395 else
3396 shift -= 4;
3397 }
3398 }
3399 break;
3400 }
3401
3402 case 8:
3403 {
3404 #ifdef PNG_READ_GAMMA_SUPPORTED
3405 if (gamma_table != NULL)
3406 {
3407 sp = row;
3408 for (i = 0; i < row_width; i++, sp++)
3409 {
3410 if (*sp == png_ptr->trans_color.gray)
3411 *sp = (png_byte)png_ptr->background.gray;
3412
3413 else
3414 *sp = gamma_table[*sp];
3415 }
3416 }
3417 else
3418 #endif
3419 {
3420 sp = row;
3421 for (i = 0; i < row_width; i++, sp++)
3422 {
3423 if (*sp == png_ptr->trans_color.gray)
3424 *sp = (png_byte)png_ptr->background.gray;
3425 }
3426 }
3427 break;
3428 }
3429
3430 case 16:
3431 {
3432 #ifdef PNG_READ_GAMMA_SUPPORTED
3433 if (gamma_16 != NULL)
3434 {
3435 sp = row;
3436 for (i = 0; i < row_width; i++, sp += 2)
3437 {
3438 png_uint_16 v;
3439
3440 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3441
3442 if (v == png_ptr->trans_color.gray)
3443 {
3444 /* Background is already in screen gamma */
3445 *sp = (png_byte)((png_ptr->background.gray >> 8)
3446 & 0xff);
3447 *(sp + 1) = (png_byte)(png_ptr->background.gray
3448 & 0xff);
3449 }
3450
3451 else
3452 {
3453 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3454 *sp = (png_byte)((v >> 8) & 0xff);
3455 *(sp + 1) = (png_byte)(v & 0xff);
3456 }
3457 }
3458 }
3459 else
3460 #endif
3461 {
3462 sp = row;
3463 for (i = 0; i < row_width; i++, sp += 2)
3464 {
3465 png_uint_16 v;
3466
3467 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3468
3469 if (v == png_ptr->trans_color.gray)
3470 {
3471 *sp = (png_byte)((png_ptr->background.gray >> 8)
3472 & 0xff);
3473 *(sp + 1) = (png_byte)(png_ptr->background.gray
3474 & 0xff);
3475 }
3476 }
3477 }
3478 break;
3479 }
3480
3481 default:
3482 break;
3483 }
3484 break;
3485 }
3486
3487 case PNG_COLOR_TYPE_RGB:
3488 {
3489 if (row_info->bit_depth == 8)
3490 {
3491 #ifdef PNG_READ_GAMMA_SUPPORTED
3492 if (gamma_table != NULL)
3493 {
3494 sp = row;
3495 for (i = 0; i < row_width; i++, sp += 3)
3496 {
3497 if (*sp == png_ptr->trans_color.red &&
3498 *(sp + 1) == png_ptr->trans_color.green &&
3499 *(sp + 2) == png_ptr->trans_color.blue)
3500 {
3501 *sp = (png_byte)png_ptr->background.red;
3502 *(sp + 1) = (png_byte)png_ptr->background.green;
3503 *(sp + 2) = (png_byte)png_ptr->background.blue;
3504 }
3505
3506 else
3507 {
3508 *sp = gamma_table[*sp];
3509 *(sp + 1) = gamma_table[*(sp + 1)];
3510 *(sp + 2) = gamma_table[*(sp + 2)];
3511 }
3512 }
3513 }
3514 else
3515 #endif
3516 {
3517 sp = row;
3518 for (i = 0; i < row_width; i++, sp += 3)
3519 {
3520 if (*sp == png_ptr->trans_color.red &&
3521 *(sp + 1) == png_ptr->trans_color.green &&
3522 *(sp + 2) == png_ptr->trans_color.blue)
3523 {
3524 *sp = (png_byte)png_ptr->background.red;
3525 *(sp + 1) = (png_byte)png_ptr->background.green;
3526 *(sp + 2) = (png_byte)png_ptr->background.blue;
3527 }
3528 }
3529 }
3530 }
3531 else /* if (row_info->bit_depth == 16) */
3532 {
3533 #ifdef PNG_READ_GAMMA_SUPPORTED
3534 if (gamma_16 != NULL)
3535 {
3536 sp = row;
3537 for (i = 0; i < row_width; i++, sp += 6)
3538 {
3539 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3540
3541 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3542 + *(sp + 3));
3543
3544 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3545 + *(sp + 5));
3546
3547 if (r == png_ptr->trans_color.red &&
3548 g == png_ptr->trans_color.green &&
3549 b == png_ptr->trans_color.blue)
3550 {
3551 /* Background is already in screen gamma */
3552 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3553 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3554 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3555 & 0xff);
3556 *(sp + 3) = (png_byte)(png_ptr->background.green
3557 & 0xff);
3558 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3559 & 0xff);
3560 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3561 }
3562
3563 else
3564 {
3565 png_uint_16 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3566 *sp = (png_byte)((v >> 8) & 0xff);
3567 *(sp + 1) = (png_byte)(v & 0xff);
3568
3569 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
3570 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3571 *(sp + 3) = (png_byte)(v & 0xff);
3572
3573 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
3574 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3575 *(sp + 5) = (png_byte)(v & 0xff);
3576 }
3577 }
3578 }
3579
3580 else
3581 #endif
3582 {
3583 sp = row;
3584 for (i = 0; i < row_width; i++, sp += 6)
3585 {
3586 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3587
3588 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3589 + *(sp + 3));
3590
3591 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3592 + *(sp + 5));
3593
3594 if (r == png_ptr->trans_color.red &&
3595 g == png_ptr->trans_color.green &&
3596 b == png_ptr->trans_color.blue)
3597 {
3598 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3599 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3600 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3601 & 0xff);
3602 *(sp + 3) = (png_byte)(png_ptr->background.green
3603 & 0xff);
3604 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3605 & 0xff);
3606 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3607 }
3608 }
3609 }
3610 }
3611 break;
3612 }
3613
3614 case PNG_COLOR_TYPE_GRAY_ALPHA:
3615 {
3616 if (row_info->bit_depth == 8)
3617 {
3618 #ifdef PNG_READ_GAMMA_SUPPORTED
3619 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
3620 gamma_table != NULL)
3621 {
3622 sp = row;
3623 for (i = 0; i < row_width; i++, sp += 2)
3624 {
3625 png_uint_16 a = *(sp + 1);
3626
3627 if (a == 0xff)
3628 *sp = gamma_table[*sp];
3629
3630 else if (a == 0)
3631 {
3632 /* Background is already in screen gamma */
3633 *sp = (png_byte)png_ptr->background.gray;
3634 }
3635
3636 else
3637 {
3638 png_byte v, w;
3639
3640 v = gamma_to_1[*sp];
3641 png_composite(w, v, a, png_ptr->background_1.gray);
3642 if (optimize == 0)
3643 w = gamma_from_1[w];
3644 *sp = w;
3645 }
3646 }
3647 }
3648 else
3649 #endif
3650 {
3651 sp = row;
3652 for (i = 0; i < row_width; i++, sp += 2)
3653 {
3654 png_byte a = *(sp + 1);
3655
3656 if (a == 0)
3657 *sp = (png_byte)png_ptr->background.gray;
3658
3659 else if (a < 0xff)
3660 png_composite(*sp, *sp, a, png_ptr->background.gray);
3661 }
3662 }
3663 }
3664 else /* if (png_ptr->bit_depth == 16) */
3665 {
3666 #ifdef PNG_READ_GAMMA_SUPPORTED
3667 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
3668 gamma_16_to_1 != NULL)
3669 {
3670 sp = row;
3671 for (i = 0; i < row_width; i++, sp += 4)
3672 {
3673 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
3674 + *(sp + 3));
3675
3676 if (a == (png_uint_16)0xffff)
3677 {
3678 png_uint_16 v;
3679
3680 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3681 *sp = (png_byte)((v >> 8) & 0xff);
3682 *(sp + 1) = (png_byte)(v & 0xff);
3683 }
3684
3685 else if (a == 0)
3686 {
3687 /* Background is already in screen gamma */
3688 *sp = (png_byte)((png_ptr->background.gray >> 8)
3689 & 0xff);
3690 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
3691 }
3692
3693 else
3694 {
3695 png_uint_16 g, v, w;
3696
3697 g = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
3698 png_composite_16(v, g, a, png_ptr->background_1.gray);
3699 if (optimize != 0)
3700 w = v;
3701 else
3702 w = gamma_16_from_1[(v & 0xff) >>
3703 gamma_shift][v >> 8];
3704 *sp = (png_byte)((w >> 8) & 0xff);
3705 *(sp + 1) = (png_byte)(w & 0xff);
3706 }
3707 }
3708 }
3709 else
3710 #endif
3711 {
3712 sp = row;
3713 for (i = 0; i < row_width; i++, sp += 4)
3714 {
3715 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
3716 + *(sp + 3));
3717
3718 if (a == 0)
3719 {
3720 *sp = (png_byte)((png_ptr->background.gray >> 8)
3721 & 0xff);
3722 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
3723 }
3724
3725 else if (a < 0xffff)
3726 {
3727 png_uint_16 g, v;
3728
3729 g = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3730 png_composite_16(v, g, a, png_ptr->background.gray);
3731 *sp = (png_byte)((v >> 8) & 0xff);
3732 *(sp + 1) = (png_byte)(v & 0xff);
3733 }
3734 }
3735 }
3736 }
3737 break;
3738 }
3739
3740 case PNG_COLOR_TYPE_RGB_ALPHA:
3741 {
3742 if (row_info->bit_depth == 8)
3743 {
3744 #ifdef PNG_READ_GAMMA_SUPPORTED
3745 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
3746 gamma_table != NULL)
3747 {
3748 sp = row;
3749 for (i = 0; i < row_width; i++, sp += 4)
3750 {
3751 png_byte a = *(sp + 3);
3752
3753 if (a == 0xff)
3754 {
3755 *sp = gamma_table[*sp];
3756 *(sp + 1) = gamma_table[*(sp + 1)];
3757 *(sp + 2) = gamma_table[*(sp + 2)];
3758 }
3759
3760 else if (a == 0)
3761 {
3762 /* Background is already in screen gamma */
3763 *sp = (png_byte)png_ptr->background.red;
3764 *(sp + 1) = (png_byte)png_ptr->background.green;
3765 *(sp + 2) = (png_byte)png_ptr->background.blue;
3766 }
3767
3768 else
3769 {
3770 png_byte v, w;
3771
3772 v = gamma_to_1[*sp];
3773 png_composite(w, v, a, png_ptr->background_1.red);
3774 if (optimize == 0) w = gamma_from_1[w];
3775 *sp = w;
3776
3777 v = gamma_to_1[*(sp + 1)];
3778 png_composite(w, v, a, png_ptr->background_1.green);
3779 if (optimize == 0) w = gamma_from_1[w];
3780 *(sp + 1) = w;
3781
3782 v = gamma_to_1[*(sp + 2)];
3783 png_composite(w, v, a, png_ptr->background_1.blue);
3784 if (optimize == 0) w = gamma_from_1[w];
3785 *(sp + 2) = w;
3786 }
3787 }
3788 }
3789 else
3790 #endif
3791 {
3792 sp = row;
3793 for (i = 0; i < row_width; i++, sp += 4)
3794 {
3795 png_byte a = *(sp + 3);
3796
3797 if (a == 0)
3798 {
3799 *sp = (png_byte)png_ptr->background.red;
3800 *(sp + 1) = (png_byte)png_ptr->background.green;
3801 *(sp + 2) = (png_byte)png_ptr->background.blue;
3802 }
3803
3804 else if (a < 0xff)
3805 {
3806 png_composite(*sp, *sp, a, png_ptr->background.red);
3807
3808 png_composite(*(sp + 1), *(sp + 1), a,
3809 png_ptr->background.green);
3810
3811 png_composite(*(sp + 2), *(sp + 2), a,
3812 png_ptr->background.blue);
3813 }
3814 }
3815 }
3816 }
3817 else /* if (row_info->bit_depth == 16) */
3818 {
3819 #ifdef PNG_READ_GAMMA_SUPPORTED
3820 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
3821 gamma_16_to_1 != NULL)
3822 {
3823 sp = row;
3824 for (i = 0; i < row_width; i++, sp += 8)
3825 {
3826 png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
3827 << 8) + (png_uint_16)(*(sp + 7)));
3828
3829 if (a == (png_uint_16)0xffff)
3830 {
3831 png_uint_16 v;
3832
3833 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3834 *sp = (png_byte)((v >> 8) & 0xff);
3835 *(sp + 1) = (png_byte)(v & 0xff);
3836
3837 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
3838 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3839 *(sp + 3) = (png_byte)(v & 0xff);
3840
3841 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
3842 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3843 *(sp + 5) = (png_byte)(v & 0xff);
3844 }
3845
3846 else if (a == 0)
3847 {
3848 /* Background is already in screen gamma */
3849 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3850 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3851 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3852 & 0xff);
3853 *(sp + 3) = (png_byte)(png_ptr->background.green
3854 & 0xff);
3855 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3856 & 0xff);
3857 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3858 }
3859
3860 else
3861 {
3862 png_uint_16 v, w;
3863
3864 v = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
3865 png_composite_16(w, v, a, png_ptr->background_1.red);
3866 if (optimize == 0)
3867 w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
3868 8];
3869 *sp = (png_byte)((w >> 8) & 0xff);
3870 *(sp + 1) = (png_byte)(w & 0xff);
3871
3872 v = gamma_16_to_1[*(sp + 3) >> gamma_shift][*(sp + 2)];
3873 png_composite_16(w, v, a, png_ptr->background_1.green);
3874 if (optimize == 0)
3875 w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
3876 8];
3877
3878 *(sp + 2) = (png_byte)((w >> 8) & 0xff);
3879 *(sp + 3) = (png_byte)(w & 0xff);
3880
3881 v = gamma_16_to_1[*(sp + 5) >> gamma_shift][*(sp + 4)];
3882 png_composite_16(w, v, a, png_ptr->background_1.blue);
3883 if (optimize == 0)
3884 w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
3885 8];
3886
3887 *(sp + 4) = (png_byte)((w >> 8) & 0xff);
3888 *(sp + 5) = (png_byte)(w & 0xff);
3889 }
3890 }
3891 }
3892
3893 else
3894 #endif
3895 {
3896 sp = row;
3897 for (i = 0; i < row_width; i++, sp += 8)
3898 {
3899 png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
3900 << 8) + (png_uint_16)(*(sp + 7)));
3901
3902 if (a == 0)
3903 {
3904 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3905 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3906 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3907 & 0xff);
3908 *(sp + 3) = (png_byte)(png_ptr->background.green
3909 & 0xff);
3910 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3911 & 0xff);
3912 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3913 }
3914
3915 else if (a < 0xffff)
3916 {
3917 png_uint_16 v;
3918
3919 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3920 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3921 + *(sp + 3));
3922 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3923 + *(sp + 5));
3924
3925 png_composite_16(v, r, a, png_ptr->background.red);
3926 *sp = (png_byte)((v >> 8) & 0xff);
3927 *(sp + 1) = (png_byte)(v & 0xff);
3928
3929 png_composite_16(v, g, a, png_ptr->background.green);
3930 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3931 *(sp + 3) = (png_byte)(v & 0xff);
3932
3933 png_composite_16(v, b, a, png_ptr->background.blue);
3934 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3935 *(sp + 5) = (png_byte)(v & 0xff);
3936 }
3937 }
3938 }
3939 }
3940 break;
3941 }
3942
3943 default:
3944 break;
3945 }
3946 }
3947 }
3948 #endif /* READ_BACKGROUND || READ_ALPHA_MODE */
3949
3950 #ifdef PNG_READ_GAMMA_SUPPORTED
3951 /* Gamma correct the image, avoiding the alpha channel. Make sure
3952 * you do this after you deal with the transparency issue on grayscale
3953 * or RGB images. If your bit depth is 8, use gamma_table, if it
3954 * is 16, use gamma_16_table and gamma_shift. Build these with
3955 * build_gamma_table().
3956 */
3957 static void
3958 png_do_gamma(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
3959 {
3960 png_const_bytep gamma_table = png_ptr->gamma_table;
3961 png_const_uint_16pp gamma_16_table = png_ptr->gamma_16_table;
3962 int gamma_shift = png_ptr->gamma_shift;
3963
3964 png_bytep sp;
3965 png_uint_32 i;
3966 png_uint_32 row_width=row_info->width;
3967
3968 png_debug(1, "in png_do_gamma");
3969
3970 if (((row_info->bit_depth <= 8 && gamma_table != NULL) ||
3971 (row_info->bit_depth == 16 && gamma_16_table != NULL)))
3972 {
3973 switch (row_info->color_type)
3974 {
3975 case PNG_COLOR_TYPE_RGB:
3976 {
3977 if (row_info->bit_depth == 8)
3978 {
3979 sp = row;
3980 for (i = 0; i < row_width; i++)
3981 {
3982 *sp = gamma_table[*sp];
3983 sp++;
3984 *sp = gamma_table[*sp];
3985 sp++;
3986 *sp = gamma_table[*sp];
3987 sp++;
3988 }
3989 }
3990
3991 else /* if (row_info->bit_depth == 16) */
3992 {
3993 sp = row;
3994 for (i = 0; i < row_width; i++)
3995 {
3996 png_uint_16 v;
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 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4009 *sp = (png_byte)((v >> 8) & 0xff);
4010 *(sp + 1) = (png_byte)(v & 0xff);
4011 sp += 2;
4012 }
4013 }
4014 break;
4015 }
4016
4017 case PNG_COLOR_TYPE_RGB_ALPHA:
4018 {
4019 if (row_info->bit_depth == 8)
4020 {
4021 sp = row;
4022 for (i = 0; i < row_width; i++)
4023 {
4024 *sp = gamma_table[*sp];
4025 sp++;
4026
4027 *sp = gamma_table[*sp];
4028 sp++;
4029
4030 *sp = gamma_table[*sp];
4031 sp++;
4032
4033 sp++;
4034 }
4035 }
4036
4037 else /* if (row_info->bit_depth == 16) */
4038 {
4039 sp = row;
4040 for (i = 0; i < row_width; i++)
4041 {
4042 png_uint_16 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 += 2;
4051
4052 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4053 *sp = (png_byte)((v >> 8) & 0xff);
4054 *(sp + 1) = (png_byte)(v & 0xff);
4055 sp += 4;
4056 }
4057 }
4058 break;
4059 }
4060
4061 case PNG_COLOR_TYPE_GRAY_ALPHA:
4062 {
4063 if (row_info->bit_depth == 8)
4064 {
4065 sp = row;
4066 for (i = 0; i < row_width; i++)
4067 {
4068 *sp = gamma_table[*sp];
4069 sp += 2;
4070 }
4071 }
4072
4073 else /* if (row_info->bit_depth == 16) */
4074 {
4075 sp = row;
4076 for (i = 0; i < row_width; i++)
4077 {
4078 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4079 *sp = (png_byte)((v >> 8) & 0xff);
4080 *(sp + 1) = (png_byte)(v & 0xff);
4081 sp += 4;
4082 }
4083 }
4084 break;
4085 }
4086
4087 case PNG_COLOR_TYPE_GRAY:
4088 {
4089 if (row_info->bit_depth == 2)
4090 {
4091 sp = row;
4092 for (i = 0; i < row_width; i += 4)
4093 {
4094 int a = *sp & 0xc0;
4095 int b = *sp & 0x30;
4096 int c = *sp & 0x0c;
4097 int d = *sp & 0x03;
4098
4099 *sp = (png_byte)(
4100 ((((int)gamma_table[a|(a>>2)|(a>>4)|(a>>6)]) ) & 0xc0)|
4101 ((((int)gamma_table[(b<<2)|b|(b>>2)|(b>>4)])>>2) & 0x30)|
4102 ((((int)gamma_table[(c<<4)|(c<<2)|c|(c>>2)])>>4) & 0x0c)|
4103 ((((int)gamma_table[(d<<6)|(d<<4)|(d<<2)|d])>>6) ));
4104 sp++;
4105 }
4106 }
4107
4108 if (row_info->bit_depth == 4)
4109 {
4110 sp = row;
4111 for (i = 0; i < row_width; i += 2)
4112 {
4113 int msb = *sp & 0xf0;
4114 int lsb = *sp & 0x0f;
4115
4116 *sp = (png_byte)((((int)gamma_table[msb | (msb >> 4)]) & 0xf0)
4117 | (((int)gamma_table[(lsb << 4) | lsb]) >> 4));
4118 sp++;
4119 }
4120 }
4121
4122 else if (row_info->bit_depth == 8)
4123 {
4124 sp = row;
4125 for (i = 0; i < row_width; i++)
4126 {
4127 *sp = gamma_table[*sp];
4128 sp++;
4129 }
4130 }
4131
4132 else if (row_info->bit_depth == 16)
4133 {
4134 sp = row;
4135 for (i = 0; i < row_width; i++)
4136 {
4137 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4138 *sp = (png_byte)((v >> 8) & 0xff);
4139 *(sp + 1) = (png_byte)(v & 0xff);
4140 sp += 2;
4141 }
4142 }
4143 break;
4144 }
4145
4146 default:
4147 break;
4148 }
4149 }
4150 }
4151 #endif
4152
4153 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
4154 /* Encode the alpha channel to the output gamma (the input channel is always
4155 * linear.) Called only with color types that have an alpha channel. Needs the
4156 * from_1 tables.
4157 */
4158 static void
4159 png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
4160 {
4161 png_uint_32 row_width = row_info->width;
4162
4163 png_debug(1, "in png_do_encode_alpha");
4164
4165 if ((row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
4166 {
4167 if (row_info->bit_depth == 8)
4168 {
4169 PNG_CONST png_bytep table = png_ptr->gamma_from_1;
4170
4171 if (table != NULL)
4172 {
4173 PNG_CONST int step =
4174 (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 4 : 2;
4175
4176 /* The alpha channel is the last component: */
4177 row += step - 1;
4178
4179 for (; row_width > 0; --row_width, row += step)
4180 *row = table[*row];
4181
4182 return;
4183 }
4184 }
4185
4186 else if (row_info->bit_depth == 16)
4187 {
4188 PNG_CONST png_uint_16pp table = png_ptr->gamma_16_from_1;
4189 PNG_CONST int gamma_shift = png_ptr->gamma_shift;
4190
4191 if (table != NULL)
4192 {
4193 PNG_CONST int step =
4194 (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 8 : 4;
4195
4196 /* The alpha channel is the last component: */
4197 row += step - 2;
4198
4199 for (; row_width > 0; --row_width, row += step)
4200 {
4201 png_uint_16 v;
4202
4203 v = table[*(row + 1) >> gamma_shift][*row];
4204 *row = (png_byte)((v >> 8) & 0xff);
4205 *(row + 1) = (png_byte)(v & 0xff);
4206 }
4207
4208 return;
4209 }
4210 }
4211 }
4212
4213 /* Only get to here if called with a weird row_info; no harm has been done,
4214 * so just issue a warning.
4215 */
4216 png_warning(png_ptr, "png_do_encode_alpha: unexpected call");
4217 }
4218 #endif
4219
4220 #ifdef PNG_READ_EXPAND_SUPPORTED
4221 /* Expands a palette row to an RGB or RGBA row depending
4222 * upon whether you supply trans and num_trans.
4223 */
4224 static void
4225 png_do_expand_palette(png_row_infop row_info, png_bytep row,
4226 png_const_colorp palette, png_const_bytep trans_alpha, int num_trans)
4227 {
4228 int shift, value;
4229 png_bytep sp, dp;
4230 png_uint_32 i;
4231 png_uint_32 row_width=row_info->width;
4232
4233 png_debug(1, "in png_do_expand_palette");
4234
4235 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
4236 {
4237 if (row_info->bit_depth < 8)
4238 {
4239 switch (row_info->bit_depth)
4240 {
4241 case 1:
4242 {
4243 sp = row + (png_size_t)((row_width - 1) >> 3);
4244 dp = row + (png_size_t)row_width - 1;
4245 shift = 7 - (int)((row_width + 7) & 0x07);
4246 for (i = 0; i < row_width; i++)
4247 {
4248 if ((*sp >> shift) & 0x01)
4249 *dp = 1;
4250
4251 else
4252 *dp = 0;
4253
4254 if (shift == 7)
4255 {
4256 shift = 0;
4257 sp--;
4258 }
4259
4260 else
4261 shift++;
4262
4263 dp--;
4264 }
4265 break;
4266 }
4267
4268 case 2:
4269 {
4270 sp = row + (png_size_t)((row_width - 1) >> 2);
4271 dp = row + (png_size_t)row_width - 1;
4272 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
4273 for (i = 0; i < row_width; i++)
4274 {
4275 value = (*sp >> shift) & 0x03;
4276 *dp = (png_byte)value;
4277 if (shift == 6)
4278 {
4279 shift = 0;
4280 sp--;
4281 }
4282
4283 else
4284 shift += 2;
4285
4286 dp--;
4287 }
4288 break;
4289 }
4290
4291 case 4:
4292 {
4293 sp = row + (png_size_t)((row_width - 1) >> 1);
4294 dp = row + (png_size_t)row_width - 1;
4295 shift = (int)((row_width & 0x01) << 2);
4296 for (i = 0; i < row_width; i++)
4297 {
4298 value = (*sp >> shift) & 0x0f;
4299 *dp = (png_byte)value;
4300 if (shift == 4)
4301 {
4302 shift = 0;
4303 sp--;
4304 }
4305
4306 else
4307 shift += 4;
4308
4309 dp--;
4310 }
4311 break;
4312 }
4313
4314 default:
4315 break;
4316 }
4317 row_info->bit_depth = 8;
4318 row_info->pixel_depth = 8;
4319 row_info->rowbytes = row_width;
4320 }
4321
4322 if (row_info->bit_depth == 8)
4323 {
4324 {
4325 if (num_trans > 0)
4326 {
4327 sp = row + (png_size_t)row_width - 1;
4328 dp = row + (png_size_t)(row_width << 2) - 1;
4329
4330 for (i = 0; i < row_width; i++)
4331 {
4332 if ((int)(*sp) >= num_trans)
4333 *dp-- = 0xff;
4334
4335 else
4336 *dp-- = trans_alpha[*sp];
4337
4338 *dp-- = palette[*sp].blue;
4339 *dp-- = palette[*sp].green;
4340 *dp-- = palette[*sp].red;
4341 sp--;
4342 }
4343 row_info->bit_depth = 8;
4344 row_info->pixel_depth = 32;
4345 row_info->rowbytes = row_width * 4;
4346 row_info->color_type = 6;
4347 row_info->channels = 4;
4348 }
4349
4350 else
4351 {
4352 sp = row + (png_size_t)row_width - 1;
4353 dp = row + (png_size_t)(row_width * 3) - 1;
4354
4355 for (i = 0; i < row_width; i++)
4356 {
4357 *dp-- = palette[*sp].blue;
4358 *dp-- = palette[*sp].green;
4359 *dp-- = palette[*sp].red;
4360 sp--;
4361 }
4362
4363 row_info->bit_depth = 8;
4364 row_info->pixel_depth = 24;
4365 row_info->rowbytes = row_width * 3;
4366 row_info->color_type = 2;
4367 row_info->channels = 3;
4368 }
4369 }
4370 }
4371 }
4372 }
4373
4374 /* If the bit depth < 8, it is expanded to 8. Also, if the already
4375 * expanded transparency value is supplied, an alpha channel is built.
4376 */
4377 static void
4378 png_do_expand(png_row_infop row_info, png_bytep row,
4379 png_const_color_16p trans_color)
4380 {
4381 int shift, value;
4382 png_bytep sp, dp;
4383 png_uint_32 i;
4384 png_uint_32 row_width=row_info->width;
4385
4386 png_debug(1, "in png_do_expand");
4387
4388 {
4389 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
4390 {
4391 unsigned int gray = trans_color != NULL ? trans_color->gray : 0;
4392
4393 if (row_info->bit_depth < 8)
4394 {
4395 switch (row_info->bit_depth)
4396 {
4397 case 1:
4398 {
4399 gray = (gray & 0x01) * 0xff;
4400 sp = row + (png_size_t)((row_width - 1) >> 3);
4401 dp = row + (png_size_t)row_width - 1;
4402 shift = 7 - (int)((row_width + 7) & 0x07);
4403 for (i = 0; i < row_width; i++)
4404 {
4405 if ((*sp >> shift) & 0x01)
4406 *dp = 0xff;
4407
4408 else
4409 *dp = 0;
4410
4411 if (shift == 7)
4412 {
4413 shift = 0;
4414 sp--;
4415 }
4416
4417 else
4418 shift++;
4419
4420 dp--;
4421 }
4422 break;
4423 }
4424
4425 case 2:
4426 {
4427 gray = (gray & 0x03) * 0x55;
4428 sp = row + (png_size_t)((row_width - 1) >> 2);
4429 dp = row + (png_size_t)row_width - 1;
4430 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
4431 for (i = 0; i < row_width; i++)
4432 {
4433 value = (*sp >> shift) & 0x03;
4434 *dp = (png_byte)(value | (value << 2) | (value << 4) |
4435 (value << 6));
4436 if (shift == 6)
4437 {
4438 shift = 0;
4439 sp--;
4440 }
4441
4442 else
4443 shift += 2;
4444
4445 dp--;
4446 }
4447 break;
4448 }
4449
4450 case 4:
4451 {
4452 gray = (gray & 0x0f) * 0x11;
4453 sp = row + (png_size_t)((row_width - 1) >> 1);
4454 dp = row + (png_size_t)row_width - 1;
4455 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
4456 for (i = 0; i < row_width; i++)
4457 {
4458 value = (*sp >> shift) & 0x0f;
4459 *dp = (png_byte)(value | (value << 4));
4460 if (shift == 4)
4461 {
4462 shift = 0;
4463 sp--;
4464 }
4465
4466 else
4467 shift = 4;
4468
4469 dp--;
4470 }
4471 break;
4472 }
4473
4474 default:
4475 break;
4476 }
4477
4478 row_info->bit_depth = 8;
4479 row_info->pixel_depth = 8;
4480 row_info->rowbytes = row_width;
4481 }
4482
4483 if (trans_color != NULL)
4484 {
4485 if (row_info->bit_depth == 8)
4486 {
4487 gray = gray & 0xff;
4488 sp = row + (png_size_t)row_width - 1;
4489 dp = row + (png_size_t)(row_width << 1) - 1;
4490
4491 for (i = 0; i < row_width; i++)
4492 {
4493 if ((*sp & 0xffU) == gray)
4494 *dp-- = 0;
4495
4496 else
4497 *dp-- = 0xff;
4498
4499 *dp-- = *sp--;
4500 }
4501 }
4502
4503 else if (row_info->bit_depth == 16)
4504 {
4505 unsigned int gray_high = (gray >> 8) & 0xff;
4506 unsigned int gray_low = gray & 0xff;
4507 sp = row + row_info->rowbytes - 1;
4508 dp = row + (row_info->rowbytes << 1) - 1;
4509 for (i = 0; i < row_width; i++)
4510 {
4511 if ((*(sp - 1) & 0xffU) == gray_high &&
4512 (*(sp) & 0xffU) == gray_low)
4513 {
4514 *dp-- = 0;
4515 *dp-- = 0;
4516 }
4517
4518 else
4519 {
4520 *dp-- = 0xff;
4521 *dp-- = 0xff;
4522 }
4523
4524 *dp-- = *sp--;
4525 *dp-- = *sp--;
4526 }
4527 }
4528
4529 row_info->color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
4530 row_info->channels = 2;
4531 row_info->pixel_depth = (png_byte)(row_info->bit_depth << 1);
4532 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
4533 row_width);
4534 }
4535 }
4536 else if (row_info->color_type == PNG_COLOR_TYPE_RGB &&
4537 trans_color != NULL)
4538 {
4539 if (row_info->bit_depth == 8)
4540 {
4541 png_byte red = (png_byte)(trans_color->red & 0xff);
4542 png_byte green = (png_byte)(trans_color->green & 0xff);
4543 png_byte blue = (png_byte)(trans_color->blue & 0xff);
4544 sp = row + (png_size_t)row_info->rowbytes - 1;
4545 dp = row + (png_size_t)(row_width << 2) - 1;
4546 for (i = 0; i < row_width; i++)
4547 {
4548 if (*(sp - 2) == red && *(sp - 1) == green && *(sp) == blue)
4549 *dp-- = 0;
4550
4551 else
4552 *dp-- = 0xff;
4553
4554 *dp-- = *sp--;
4555 *dp-- = *sp--;
4556 *dp-- = *sp--;
4557 }
4558 }
4559 else if (row_info->bit_depth == 16)
4560 {
4561 png_byte red_high = (png_byte)((trans_color->red >> 8) & 0xff);
4562 png_byte green_high = (png_byte)((trans_color->green >> 8) & 0xff);
4563 png_byte blue_high = (png_byte)((trans_color->blue >> 8) & 0xff);
4564 png_byte red_low = (png_byte)(trans_color->red & 0xff);
4565 png_byte green_low = (png_byte)(trans_color->green & 0xff);
4566 png_byte blue_low = (png_byte)(trans_color->blue & 0xff);
4567 sp = row + row_info->rowbytes - 1;
4568 dp = row + (png_size_t)(row_width << 3) - 1;
4569 for (i = 0; i < row_width; i++)
4570 {
4571 if (*(sp - 5) == red_high &&
4572 *(sp - 4) == red_low &&
4573 *(sp - 3) == green_high &&
4574 *(sp - 2) == green_low &&
4575 *(sp - 1) == blue_high &&
4576 *(sp ) == blue_low)
4577 {
4578 *dp-- = 0;
4579 *dp-- = 0;
4580 }
4581
4582 else
4583 {
4584 *dp-- = 0xff;
4585 *dp-- = 0xff;
4586 }
4587
4588 *dp-- = *sp--;
4589 *dp-- = *sp--;
4590 *dp-- = *sp--;
4591 *dp-- = *sp--;
4592 *dp-- = *sp--;
4593 *dp-- = *sp--;
4594 }
4595 }
4596 row_info->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
4597 row_info->channels = 4;
4598 row_info->pixel_depth = (png_byte)(row_info->bit_depth << 2);
4599 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4600 }
4601 }
4602 }
4603 #endif
4604
4605 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4606 /* If the bit depth is 8 and the color type is not a palette type expand the
4607 * whole row to 16 bits. Has no effect otherwise.
4608 */
4609 static void
4610 png_do_expand_16(png_row_infop row_info, png_bytep row)
4611 {
4612 if (row_info->bit_depth == 8 &&
4613 row_info->color_type != PNG_COLOR_TYPE_PALETTE)
4614 {
4615 /* The row have a sequence of bytes containing [0..255] and we need
4616 * to turn it into another row containing [0..65535], to do this we
4617 * calculate:
4618 *
4619 * (input / 255) * 65535
4620 *
4621 * Which happens to be exactly input * 257 and this can be achieved
4622 * simply by byte replication in place (copying backwards).
4623 */
4624 png_byte *sp = row + row_info->rowbytes; /* source, last byte + 1 */
4625 png_byte *dp = sp + row_info->rowbytes; /* destination, end + 1 */
4626 while (dp > sp)
4627 dp[-2] = dp[-1] = *--sp, dp -= 2;
4628
4629 row_info->rowbytes *= 2;
4630 row_info->bit_depth = 16;
4631 row_info->pixel_depth = (png_byte)(row_info->channels * 16);
4632 }
4633 }
4634 #endif
4635
4636 #ifdef PNG_READ_QUANTIZE_SUPPORTED
4637 static void
4638 png_do_quantize(png_row_infop row_info, png_bytep row,
4639 png_const_bytep palette_lookup, png_const_bytep quantize_lookup)
4640 {
4641 png_bytep sp, dp;
4642 png_uint_32 i;
4643 png_uint_32 row_width=row_info->width;
4644
4645 png_debug(1, "in png_do_quantize");
4646
4647 if (row_info->bit_depth == 8)
4648 {
4649 if (row_info->color_type == PNG_COLOR_TYPE_RGB && palette_lookup)
4650 {
4651 int r, g, b, p;
4652 sp = row;
4653 dp = row;
4654 for (i = 0; i < row_width; i++)
4655 {
4656 r = *sp++;
4657 g = *sp++;
4658 b = *sp++;
4659
4660 /* This looks real messy, but the compiler will reduce
4661 * it down to a reasonable formula. For example, with
4662 * 5 bits per color, we get:
4663 * p = (((r >> 3) & 0x1f) << 10) |
4664 * (((g >> 3) & 0x1f) << 5) |
4665 * ((b >> 3) & 0x1f);
4666 */
4667 p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
4668 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
4669 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
4670 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
4671 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
4672 (PNG_QUANTIZE_BLUE_BITS)) |
4673 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
4674 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
4675
4676 *dp++ = palette_lookup[p];
4677 }
4678
4679 row_info->color_type = PNG_COLOR_TYPE_PALETTE;
4680 row_info->channels = 1;
4681 row_info->pixel_depth = row_info->bit_depth;
4682 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4683 }
4684
4685 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
4686 palette_lookup != NULL)
4687 {
4688 int r, g, b, p;
4689 sp = row;
4690 dp = row;
4691 for (i = 0; i < row_width; i++)
4692 {
4693 r = *sp++;
4694 g = *sp++;
4695 b = *sp++;
4696 sp++;
4697
4698 p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
4699 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
4700 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
4701 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
4702 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
4703 (PNG_QUANTIZE_BLUE_BITS)) |
4704 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
4705 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
4706
4707 *dp++ = palette_lookup[p];
4708 }
4709
4710 row_info->color_type = PNG_COLOR_TYPE_PALETTE;
4711 row_info->channels = 1;
4712 row_info->pixel_depth = row_info->bit_depth;
4713 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4714 }
4715
4716 else if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
4717 quantize_lookup)
4718 {
4719 sp = row;
4720
4721 for (i = 0; i < row_width; i++, sp++)
4722 {
4723 *sp = quantize_lookup[*sp];
4724 }
4725 }
4726 }
4727 }
4728 #endif /* READ_QUANTIZE */
4729
4730 /* Transform the row. The order of transformations is significant,
4731 * and is very touchy. If you add a transformation, take care to
4732 * decide how it fits in with the other transformations here.
4733 */
4734 void /* PRIVATE */
4735 png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
4736 {
4737 png_debug(1, "in png_do_read_transformations");
4738
4739 if (png_ptr->row_buf == NULL)
4740 {
4741 /* Prior to 1.5.4 this output row/pass where the NULL pointer is, but this
4742 * error is incredibly rare and incredibly easy to debug without this
4743 * information.
4744 */
4745 png_error(png_ptr, "NULL row buffer");
4746 }
4747
4748 /* The following is debugging; prior to 1.5.4 the code was never compiled in;
4749 * in 1.5.4 PNG_FLAG_DETECT_UNINITIALIZED was added and the macro
4750 * PNG_WARN_UNINITIALIZED_ROW removed. In 1.6 the new flag is set only for
4751 * all transformations, however in practice the ROW_INIT always gets done on
4752 * demand, if necessary.
4753 */
4754 if ((png_ptr->flags & PNG_FLAG_DETECT_UNINITIALIZED) != 0 &&
4755 (png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
4756 {
4757 /* Application has failed to call either png_read_start_image() or
4758 * png_read_update_info() after setting transforms that expand pixels.
4759 * This check added to libpng-1.2.19 (but not enabled until 1.5.4).
4760 */
4761 png_error(png_ptr, "Uninitialized row");
4762 }
4763
4764 #ifdef PNG_READ_EXPAND_SUPPORTED
4765 if ((png_ptr->transformations & PNG_EXPAND) != 0)
4766 {
4767 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
4768 {
4769 png_do_expand_palette(row_info, png_ptr->row_buf + 1,
4770 png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans);
4771 }
4772
4773 else
4774 {
4775 if (png_ptr->num_trans != 0 &&
4776 (png_ptr->transformations & PNG_EXPAND_tRNS) != 0)
4777 png_do_expand(row_info, png_ptr->row_buf + 1,
4778 &(png_ptr->trans_color));
4779
4780 else
4781 png_do_expand(row_info, png_ptr->row_buf + 1,
4782 NULL);
4783 }
4784 }
4785 #endif
4786
4787 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
4788 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
4789 (png_ptr->transformations & PNG_COMPOSE) == 0 &&
4790 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
4791 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
4792 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
4793 0 /* at_start == false, because SWAP_ALPHA happens later */);
4794 #endif
4795
4796 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
4797 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
4798 {
4799 int rgb_error =
4800 png_do_rgb_to_gray(png_ptr, row_info,
4801 png_ptr->row_buf + 1);
4802
4803 if (rgb_error != 0)
4804 {
4805 png_ptr->rgb_to_gray_status=1;
4806 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
4807 PNG_RGB_TO_GRAY_WARN)
4808 png_warning(png_ptr, "png_do_rgb_to_gray found nongray pixel");
4809
4810 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
4811 PNG_RGB_TO_GRAY_ERR)
4812 png_error(png_ptr, "png_do_rgb_to_gray found nongray pixel");
4813 }
4814 }
4815 #endif
4816
4817 /* From Andreas Dilger e-mail to png-implement, 26 March 1998:
4818 *
4819 * In most cases, the "simple transparency" should be done prior to doing
4820 * gray-to-RGB, or you will have to test 3x as many bytes to check if a
4821 * pixel is transparent. You would also need to make sure that the
4822 * transparency information is upgraded to RGB.
4823 *
4824 * To summarize, the current flow is:
4825 * - Gray + simple transparency -> compare 1 or 2 gray bytes and composite
4826 * with background "in place" if transparent,
4827 * convert to RGB if necessary
4828 * - Gray + alpha -> composite with gray background and remove alpha bytes,
4829 * convert to RGB if necessary
4830 *
4831 * To support RGB backgrounds for gray images we need:
4832 * - Gray + simple transparency -> convert to RGB + simple transparency,
4833 * compare 3 or 6 bytes and composite with
4834 * background "in place" if transparent
4835 * (3x compare/pixel compared to doing
4836 * composite with gray bkgrnd)
4837 * - Gray + alpha -> convert to RGB + alpha, composite with background and
4838 * remove alpha bytes (3x float
4839 * operations/pixel compared with composite
4840 * on gray background)
4841 *
4842 * Greg's change will do this. The reason it wasn't done before is for
4843 * performance, as this increases the per-pixel operations. If we would check
4844 * in advance if the background was gray or RGB, and position the gray-to-RGB
4845 * transform appropriately, then it would save a lot of work/time.
4846 */
4847
4848 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4849 /* If gray -> RGB, do so now only if background is non-gray; else do later
4850 * for performance reasons
4851 */
4852 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 &&
4853 (png_ptr->mode & PNG_BACKGROUND_IS_GRAY) == 0)
4854 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
4855 #endif
4856
4857 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
4858 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
4859 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
4860 png_do_compose(row_info, png_ptr->row_buf + 1, png_ptr);
4861 #endif
4862
4863 #ifdef PNG_READ_GAMMA_SUPPORTED
4864 if ((png_ptr->transformations & PNG_GAMMA) != 0 &&
4865 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
4866 /* Because RGB_TO_GRAY does the gamma transform. */
4867 (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0 &&
4868 #endif
4869 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
4870 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
4871 /* Because PNG_COMPOSE does the gamma transform if there is something to
4872 * do (if there is an alpha channel or transparency.)
4873 */
4874 !((png_ptr->transformations & PNG_COMPOSE) != 0 &&
4875 ((png_ptr->num_trans != 0) ||
4876 (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)) &&
4877 #endif
4878 /* Because png_init_read_transformations transforms the palette, unless
4879 * RGB_TO_GRAY will do the transform.
4880 */
4881 (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE))
4882 png_do_gamma(row_info, png_ptr->row_buf + 1, png_ptr);
4883 #endif
4884
4885 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
4886 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
4887 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
4888 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
4889 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
4890 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
4891 0 /* at_start == false, because SWAP_ALPHA happens later */);
4892 #endif
4893
4894 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
4895 if ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 &&
4896 (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
4897 png_do_encode_alpha(row_info, png_ptr->row_buf + 1, png_ptr);
4898 #endif
4899
4900 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
4901 if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0)
4902 png_do_scale_16_to_8(row_info, png_ptr->row_buf + 1);
4903 #endif
4904
4905 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
4906 /* There is no harm in doing both of these because only one has any effect,
4907 * by putting the 'scale' option first if the app asks for scale (either by
4908 * calling the API or in a TRANSFORM flag) this is what happens.
4909 */
4910 if ((png_ptr->transformations & PNG_16_TO_8) != 0)
4911 png_do_chop(row_info, png_ptr->row_buf + 1);
4912 #endif
4913
4914 #ifdef PNG_READ_QUANTIZE_SUPPORTED
4915 if ((png_ptr->transformations & PNG_QUANTIZE) != 0)
4916 {
4917 png_do_quantize(row_info, png_ptr->row_buf + 1,
4918 png_ptr->palette_lookup, png_ptr->quantize_index);
4919
4920 if (row_info->rowbytes == 0)
4921 png_error(png_ptr, "png_do_quantize returned rowbytes=0");
4922 }
4923 #endif /* READ_QUANTIZE */
4924
4925 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4926 /* Do the expansion now, after all the arithmetic has been done. Notice
4927 * that previous transformations can handle the PNG_EXPAND_16 flag if this
4928 * is efficient (particularly true in the case of gamma correction, where
4929 * better accuracy results faster!)
4930 */
4931 if ((png_ptr->transformations & PNG_EXPAND_16) != 0)
4932 png_do_expand_16(row_info, png_ptr->row_buf + 1);
4933 #endif
4934
4935 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4936 /* NOTE: moved here in 1.5.4 (from much later in this list.) */
4937 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 &&
4938 (png_ptr->mode & PNG_BACKGROUND_IS_GRAY) != 0)
4939 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
4940 #endif
4941
4942 #ifdef PNG_READ_INVERT_SUPPORTED
4943 if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
4944 png_do_invert(row_info, png_ptr->row_buf + 1);
4945 #endif
4946
4947 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
4948 if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
4949 png_do_read_invert_alpha(row_info, png_ptr->row_buf + 1);
4950 #endif
4951
4952 #ifdef PNG_READ_SHIFT_SUPPORTED
4953 if ((png_ptr->transformations & PNG_SHIFT) != 0)
4954 png_do_unshift(row_info, png_ptr->row_buf + 1,
4955 &(png_ptr->shift));
4956 #endif
4957
4958 #ifdef PNG_READ_PACK_SUPPORTED
4959 if ((png_ptr->transformations & PNG_PACK) != 0)
4960 png_do_unpack(row_info, png_ptr->row_buf + 1);
4961 #endif
4962
4963 #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
4964 /* Added at libpng-1.5.10 */
4965 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
4966 png_ptr->num_palette_max >= 0)
4967 png_do_check_palette_indexes(png_ptr, row_info);
4968 #endif
4969
4970 #ifdef PNG_READ_BGR_SUPPORTED
4971 if ((png_ptr->transformations & PNG_BGR) != 0)
4972 png_do_bgr(row_info, png_ptr->row_buf + 1);
4973 #endif
4974
4975 #ifdef PNG_READ_PACKSWAP_SUPPORTED
4976 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
4977 png_do_packswap(row_info, png_ptr->row_buf + 1);
4978 #endif
4979
4980 #ifdef PNG_READ_FILLER_SUPPORTED
4981 if ((png_ptr->transformations & PNG_FILLER) != 0)
4982 png_do_read_filler(row_info, png_ptr->row_buf + 1,
4983 (png_uint_32)png_ptr->filler, png_ptr->flags);
4984 #endif
4985
4986 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
4987 if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0)
4988 png_do_read_swap_alpha(row_info, png_ptr->row_buf + 1);
4989 #endif
4990
4991 #ifdef PNG_READ_16BIT_SUPPORTED
4992 #ifdef PNG_READ_SWAP_SUPPORTED
4993 if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
4994 png_do_swap(row_info, png_ptr->row_buf + 1);
4995 #endif
4996 #endif
4997
4998 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
4999 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
5000 {
5001 if (png_ptr->read_user_transform_fn != NULL)
5002 (*(png_ptr->read_user_transform_fn)) /* User read transform function */
5003 (png_ptr, /* png_ptr */
5004 row_info, /* row_info: */
5005 /* png_uint_32 width; width of row */
5006 /* png_size_t rowbytes; number of bytes in row */
5007 /* png_byte color_type; color type of pixels */
5008 /* png_byte bit_depth; bit depth of samples */
5009 /* png_byte channels; number of channels (1-4) */
5010 /* png_byte pixel_depth; bits per pixel (depth*channels) */
5011 png_ptr->row_buf + 1); /* start of pixel data for row */
5012 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
5013 if (png_ptr->user_transform_depth != 0)
5014 row_info->bit_depth = png_ptr->user_transform_depth;
5015
5016 if (png_ptr->user_transform_channels != 0)
5017 row_info->channels = png_ptr->user_transform_channels;
5018 #endif
5019 row_info->pixel_depth = (png_byte)(row_info->bit_depth *
5020 row_info->channels);
5021
5022 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_info->width);
5023 }
5024 #endif
5025 }
5026
5027 #endif /* READ_TRANSFORMS */
5028 #endif /* READ */