1
2 /* pngread.c - read a PNG file
3 *
4 * Copyright (c) 2018-2019 Cosmin Truta
5 * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
6 * Copyright (c) 1996-1997 Andreas Dilger
7 * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
8 *
9 * This code is released under the libpng license.
10 * For conditions of distribution and use, see the disclaimer
11 * and license in png.h
12 *
13 * This file contains routines that an application calls directly to
14 * read a PNG file or stream.
15 */
16
17 #include "pngpriv.h"
18 #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) && defined(PNG_STDIO_SUPPORTED)
19 # include <errno.h>
20 #endif
21
22 #ifdef PNG_READ_SUPPORTED
23
24 /* Create a PNG structure for reading, and allocate any memory needed. */
25 PNG_FUNCTION(png_structp,PNGAPI
26 png_create_read_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
27 png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED)
28 {
29 #ifndef PNG_USER_MEM_SUPPORTED
30 png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
31 error_fn, warn_fn, NULL, NULL, NULL);
32 #else
33 return png_create_read_struct_2(user_png_ver, error_ptr, error_fn,
34 warn_fn, NULL, NULL, NULL);
35 }
36
37 /* Alternate create PNG structure for reading, and allocate any memory
38 * needed.
39 */
40 PNG_FUNCTION(png_structp,PNGAPI
41 png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
42 png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
43 png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
44 {
45 png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
46 error_fn, warn_fn, mem_ptr, malloc_fn, free_fn);
47 #endif /* USER_MEM */
48
49 if (png_ptr != NULL)
50 {
51 png_ptr->mode = PNG_IS_READ_STRUCT;
52
53 /* Added in libpng-1.6.0; this can be used to detect a read structure if
54 * required (it will be zero in a write structure.)
55 */
56 # ifdef PNG_SEQUENTIAL_READ_SUPPORTED
57 #ifdef PNG_MULTY_LINE_ENABLE
58 // OH ISSUE: png optimize
59 png_ptr->IDAT_read_size = PNG_INFLATE_MAX_SIZE;
60 #else
61 png_ptr->IDAT_read_size = PNG_IDAT_READ_SIZE;
62 #endif
63 # endif
64
65 # ifdef PNG_BENIGN_READ_ERRORS_SUPPORTED
66 png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN;
67
68 /* In stable builds only warn if an application error can be completely
69 * handled.
70 */
71 # if PNG_RELEASE_BUILD
72 png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN;
73 # endif
74 # endif
75
76 /* TODO: delay this, it can be done in png_init_io (if the app doesn't
77 * do it itself) avoiding setting the default function if it is not
78 * required.
79 */
80 png_set_read_fn(png_ptr, NULL, NULL);
81 }
82
83 return png_ptr;
84 }
85
86
87 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
88 /* Read the information before the actual image data. This has been
89 * changed in v0.90 to allow reading a file that already has the magic
90 * bytes read from the stream. You can tell libpng how many bytes have
91 * been read from the beginning of the stream (up to the maximum of 8)
92 * via png_set_sig_bytes(), and we will only check the remaining bytes
93 * here. The application can then have access to the signature bytes we
94 * read if it is determined that this isn't a valid PNG file.
95 */
96 void PNGAPI
png_read_info(png_structrp png_ptr,png_inforp info_ptr)97 png_read_info(png_structrp png_ptr, png_inforp info_ptr)
98 {
99 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
100 int keep;
101 #endif
102
103 png_debug(1, "in png_read_info");
104
105 if (png_ptr == NULL || info_ptr == NULL)
106 return;
107
108 /* Read and check the PNG file signature. */
109 png_read_sig(png_ptr, info_ptr);
110
111 for (;;)
112 {
113 png_uint_32 length = png_read_chunk_header(png_ptr);
114 png_uint_32 chunk_name = png_ptr->chunk_name;
115
116 /* IDAT logic needs to happen here to simplify getting the two flags
117 * right.
118 */
119 if (chunk_name == png_IDAT)
120 {
121 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
122 png_chunk_error(png_ptr, "Missing IHDR before IDAT");
123
124 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
125 (png_ptr->mode & PNG_HAVE_PLTE) == 0)
126 png_chunk_error(png_ptr, "Missing PLTE before IDAT");
127
128 else if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
129 png_chunk_benign_error(png_ptr, "Too many IDATs found");
130
131 png_ptr->mode |= PNG_HAVE_IDAT;
132 }
133
134 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
135 {
136 png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
137 png_ptr->mode |= PNG_AFTER_IDAT;
138 }
139
140 /* This should be a binary subdivision search or a hash for
141 * matching the chunk name rather than a linear search.
142 */
143 if (chunk_name == png_IHDR)
144 png_handle_IHDR(png_ptr, info_ptr, length);
145
146 else if (chunk_name == png_IEND)
147 png_handle_IEND(png_ptr, info_ptr, length);
148
149 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
150 else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
151 {
152 png_handle_unknown(png_ptr, info_ptr, length, keep);
153
154 if (chunk_name == png_PLTE)
155 png_ptr->mode |= PNG_HAVE_PLTE;
156
157 else if (chunk_name == png_IDAT)
158 {
159 png_ptr->idat_size = 0; /* It has been consumed */
160 break;
161 }
162 }
163 #endif
164 else if (chunk_name == png_PLTE)
165 png_handle_PLTE(png_ptr, info_ptr, length);
166
167 else if (chunk_name == png_IDAT)
168 {
169 png_ptr->idat_size = length;
170 break;
171 }
172
173 #ifdef PNG_READ_bKGD_SUPPORTED
174 else if (chunk_name == png_bKGD)
175 png_handle_bKGD(png_ptr, info_ptr, length);
176 #endif
177
178 #ifdef PNG_READ_cHRM_SUPPORTED
179 else if (chunk_name == png_cHRM)
180 png_handle_cHRM(png_ptr, info_ptr, length);
181 #endif
182
183 #ifdef PNG_READ_eXIf_SUPPORTED
184 else if (chunk_name == png_eXIf)
185 png_handle_eXIf(png_ptr, info_ptr, length);
186 #endif
187
188 #ifdef PNG_READ_gAMA_SUPPORTED
189 else if (chunk_name == png_gAMA)
190 png_handle_gAMA(png_ptr, info_ptr, length);
191 #endif
192
193 #ifdef PNG_READ_hIST_SUPPORTED
194 else if (chunk_name == png_hIST)
195 png_handle_hIST(png_ptr, info_ptr, length);
196 #endif
197
198 #ifdef PNG_READ_oFFs_SUPPORTED
199 else if (chunk_name == png_oFFs)
200 png_handle_oFFs(png_ptr, info_ptr, length);
201 #endif
202
203 #ifdef PNG_READ_pCAL_SUPPORTED
204 else if (chunk_name == png_pCAL)
205 png_handle_pCAL(png_ptr, info_ptr, length);
206 #endif
207
208 #ifdef PNG_READ_sCAL_SUPPORTED
209 else if (chunk_name == png_sCAL)
210 png_handle_sCAL(png_ptr, info_ptr, length);
211 #endif
212
213 #ifdef PNG_READ_pHYs_SUPPORTED
214 else if (chunk_name == png_pHYs)
215 png_handle_pHYs(png_ptr, info_ptr, length);
216 #endif
217
218 #ifdef PNG_READ_sBIT_SUPPORTED
219 else if (chunk_name == png_sBIT)
220 png_handle_sBIT(png_ptr, info_ptr, length);
221 #endif
222
223 #ifdef PNG_READ_sRGB_SUPPORTED
224 else if (chunk_name == png_sRGB)
225 png_handle_sRGB(png_ptr, info_ptr, length);
226 #endif
227
228 #ifdef PNG_READ_iCCP_SUPPORTED
229 else if (chunk_name == png_iCCP)
230 png_handle_iCCP(png_ptr, info_ptr, length);
231 #endif
232
233 #ifdef PNG_READ_sPLT_SUPPORTED
234 else if (chunk_name == png_sPLT)
235 png_handle_sPLT(png_ptr, info_ptr, length);
236 #endif
237
238 #ifdef PNG_READ_tEXt_SUPPORTED
239 else if (chunk_name == png_tEXt)
240 png_handle_tEXt(png_ptr, info_ptr, length);
241 #endif
242
243 #ifdef PNG_READ_tIME_SUPPORTED
244 else if (chunk_name == png_tIME)
245 png_handle_tIME(png_ptr, info_ptr, length);
246 #endif
247
248 #ifdef PNG_READ_tRNS_SUPPORTED
249 else if (chunk_name == png_tRNS)
250 png_handle_tRNS(png_ptr, info_ptr, length);
251 #endif
252
253 #ifdef PNG_READ_zTXt_SUPPORTED
254 else if (chunk_name == png_zTXt)
255 png_handle_zTXt(png_ptr, info_ptr, length);
256 #endif
257
258 #ifdef PNG_READ_iTXt_SUPPORTED
259 else if (chunk_name == png_iTXt)
260 png_handle_iTXt(png_ptr, info_ptr, length);
261 #endif
262
263 else
264 png_handle_unknown(png_ptr, info_ptr, length,
265 PNG_HANDLE_CHUNK_AS_DEFAULT);
266 }
267 }
268 #endif /* SEQUENTIAL_READ */
269
270 /* Optional call to update the users info_ptr structure */
271 void PNGAPI
png_read_update_info(png_structrp png_ptr,png_inforp info_ptr)272 png_read_update_info(png_structrp png_ptr, png_inforp info_ptr)
273 {
274 png_debug(1, "in png_read_update_info");
275
276 if (png_ptr != NULL)
277 {
278 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
279 {
280 png_read_start_row(png_ptr);
281
282 # ifdef PNG_READ_TRANSFORMS_SUPPORTED
283 png_read_transform_info(png_ptr, info_ptr);
284 # else
285 PNG_UNUSED(info_ptr)
286 # endif
287 }
288
289 /* New in 1.6.0 this avoids the bug of doing the initializations twice */
290 else
291 png_app_error(png_ptr,
292 "png_read_update_info/png_start_read_image: duplicate call");
293 }
294 }
295
296 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
297 /* Initialize palette, background, etc, after transformations
298 * are set, but before any reading takes place. This allows
299 * the user to obtain a gamma-corrected palette, for example.
300 * If the user doesn't call this, we will do it ourselves.
301 */
302 void PNGAPI
png_start_read_image(png_structrp png_ptr)303 png_start_read_image(png_structrp png_ptr)
304 {
305 png_debug(1, "in png_start_read_image");
306
307 if (png_ptr != NULL)
308 {
309 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
310 png_read_start_row(png_ptr);
311
312 /* New in 1.6.0 this avoids the bug of doing the initializations twice */
313 else
314 png_app_error(png_ptr,
315 "png_start_read_image/png_read_update_info: duplicate call");
316 }
317 }
318 #endif /* SEQUENTIAL_READ */
319
320 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
321 #ifdef PNG_MNG_FEATURES_SUPPORTED
322 /* Undoes intrapixel differencing,
323 * NOTE: this is apparently only supported in the 'sequential' reader.
324 */
325 static void
png_do_read_intrapixel(png_row_infop row_info,png_bytep row)326 png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
327 {
328 png_debug(1, "in png_do_read_intrapixel");
329
330 if (
331 (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
332 {
333 int bytes_per_pixel;
334 png_uint_32 row_width = row_info->width;
335
336 if (row_info->bit_depth == 8)
337 {
338 png_bytep rp;
339 png_uint_32 i;
340
341 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
342 bytes_per_pixel = 3;
343
344 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
345 bytes_per_pixel = 4;
346
347 else
348 return;
349
350 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
351 {
352 *(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff);
353 *(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff);
354 }
355 }
356 else if (row_info->bit_depth == 16)
357 {
358 png_bytep rp;
359 png_uint_32 i;
360
361 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
362 bytes_per_pixel = 6;
363
364 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
365 bytes_per_pixel = 8;
366
367 else
368 return;
369
370 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
371 {
372 png_uint_32 s0 = (png_uint_32)(*(rp ) << 8) | *(rp + 1);
373 png_uint_32 s1 = (png_uint_32)(*(rp + 2) << 8) | *(rp + 3);
374 png_uint_32 s2 = (png_uint_32)(*(rp + 4) << 8) | *(rp + 5);
375 png_uint_32 red = (s0 + s1 + 65536) & 0xffff;
376 png_uint_32 blue = (s2 + s1 + 65536) & 0xffff;
377 *(rp ) = (png_byte)((red >> 8) & 0xff);
378 *(rp + 1) = (png_byte)(red & 0xff);
379 *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
380 *(rp + 5) = (png_byte)(blue & 0xff);
381 }
382 }
383 }
384 }
385 #endif /* MNG_FEATURES */
386
387 void PNGAPI
png_read_row(png_structrp png_ptr,png_bytep row,png_bytep dsp_row)388 png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)
389 {
390 png_row_info row_info;
391
392 if (png_ptr == NULL)
393 return;
394
395 png_debug2(1, "in png_read_row (row %lu, pass %d)",
396 (unsigned long)png_ptr->row_number, png_ptr->pass);
397
398 /* png_read_start_row sets the information (in particular iwidth) for this
399 * interlace pass.
400 */
401 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
402 png_read_start_row(png_ptr);
403
404 /* 1.5.6: row_info moved out of png_struct to a local here. */
405 row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
406 row_info.color_type = png_ptr->color_type;
407 row_info.bit_depth = png_ptr->bit_depth;
408 row_info.channels = png_ptr->channels;
409 row_info.pixel_depth = png_ptr->pixel_depth;
410 row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
411
412 #ifdef PNG_WARNINGS_SUPPORTED
413 if (png_ptr->row_number == 0 && png_ptr->pass == 0)
414 {
415 /* Check for transforms that have been set but were defined out */
416 #if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED)
417 if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
418 png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined");
419 #endif
420
421 #if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED)
422 if ((png_ptr->transformations & PNG_FILLER) != 0)
423 png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined");
424 #endif
425
426 #if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
427 !defined(PNG_READ_PACKSWAP_SUPPORTED)
428 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
429 png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined");
430 #endif
431
432 #if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED)
433 if ((png_ptr->transformations & PNG_PACK) != 0)
434 png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined");
435 #endif
436
437 #if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED)
438 if ((png_ptr->transformations & PNG_SHIFT) != 0)
439 png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined");
440 #endif
441
442 #if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED)
443 if ((png_ptr->transformations & PNG_BGR) != 0)
444 png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined");
445 #endif
446
447 #if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED)
448 if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
449 png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined");
450 #endif
451 }
452 #endif /* WARNINGS */
453
454 #ifdef PNG_READ_INTERLACING_SUPPORTED
455 /* If interlaced and we do not need a new row, combine row and return.
456 * Notice that the pixels we have from previous rows have been transformed
457 * already; we can only combine like with like (transformed or
458 * untransformed) and, because of the libpng API for interlaced images, this
459 * means we must transform before de-interlacing.
460 */
461 if (png_ptr->interlaced != 0 &&
462 (png_ptr->transformations & PNG_INTERLACE) != 0)
463 {
464 switch (png_ptr->pass)
465 {
466 case 0:
467 if (png_ptr->row_number & 0x07)
468 {
469 if (dsp_row != NULL)
470 png_combine_row(png_ptr, dsp_row, 1/*display*/);
471 png_read_finish_row(png_ptr);
472 return;
473 }
474 break;
475
476 case 1:
477 if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
478 {
479 if (dsp_row != NULL)
480 png_combine_row(png_ptr, dsp_row, 1/*display*/);
481
482 png_read_finish_row(png_ptr);
483 return;
484 }
485 break;
486
487 case 2:
488 if ((png_ptr->row_number & 0x07) != 4)
489 {
490 if (dsp_row != NULL && (png_ptr->row_number & 4))
491 png_combine_row(png_ptr, dsp_row, 1/*display*/);
492
493 png_read_finish_row(png_ptr);
494 return;
495 }
496 break;
497
498 case 3:
499 if ((png_ptr->row_number & 3) || png_ptr->width < 3)
500 {
501 if (dsp_row != NULL)
502 png_combine_row(png_ptr, dsp_row, 1/*display*/);
503
504 png_read_finish_row(png_ptr);
505 return;
506 }
507 break;
508
509 case 4:
510 if ((png_ptr->row_number & 3) != 2)
511 {
512 if (dsp_row != NULL && (png_ptr->row_number & 2))
513 png_combine_row(png_ptr, dsp_row, 1/*display*/);
514
515 png_read_finish_row(png_ptr);
516 return;
517 }
518 break;
519
520 case 5:
521 if ((png_ptr->row_number & 1) || png_ptr->width < 2)
522 {
523 if (dsp_row != NULL)
524 png_combine_row(png_ptr, dsp_row, 1/*display*/);
525
526 png_read_finish_row(png_ptr);
527 return;
528 }
529 break;
530
531 default:
532 case 6:
533 if ((png_ptr->row_number & 1) == 0)
534 {
535 png_read_finish_row(png_ptr);
536 return;
537 }
538 break;
539 }
540 }
541 #endif
542
543 if ((png_ptr->mode & PNG_HAVE_IDAT) == 0)
544 png_error(png_ptr, "Invalid attempt to read row data");
545
546 /* Fill the row with IDAT data: */
547 png_ptr->row_buf[0]=255; /* to force error if no data was found */
548 png_read_IDAT_data(png_ptr, png_ptr->row_buf, row_info.rowbytes + 1);
549
550 if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
551 {
552 if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
553 png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
554 png_ptr->prev_row + 1, png_ptr->row_buf[0]);
555 else
556 png_error(png_ptr, "bad adaptive filter value");
557 }
558
559 /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
560 * 1.5.6, while the buffer really is this big in current versions of libpng
561 * it may not be in the future, so this was changed just to copy the
562 * interlaced count:
563 */
564 memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
565
566 #ifdef PNG_MNG_FEATURES_SUPPORTED
567 if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
568 (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
569 {
570 /* Intrapixel differencing */
571 png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1);
572 }
573 #endif
574
575 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
576 if (png_ptr->transformations)
577 png_do_read_transformations(png_ptr, &row_info);
578 #endif
579
580 /* The transformed pixel depth should match the depth now in row_info. */
581 if (png_ptr->transformed_pixel_depth == 0)
582 {
583 png_ptr->transformed_pixel_depth = row_info.pixel_depth;
584 if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
585 png_error(png_ptr, "sequential row overflow");
586 }
587
588 else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
589 png_error(png_ptr, "internal sequential row size calculation error");
590
591 #ifdef PNG_READ_INTERLACING_SUPPORTED
592 /* Expand interlaced rows to full size */
593 if (png_ptr->interlaced != 0 &&
594 (png_ptr->transformations & PNG_INTERLACE) != 0)
595 {
596 if (png_ptr->pass < 6)
597 png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
598 png_ptr->transformations);
599
600 if (dsp_row != NULL)
601 png_combine_row(png_ptr, dsp_row, 1/*display*/);
602
603 if (row != NULL)
604 png_combine_row(png_ptr, row, 0/*row*/);
605 }
606
607 else
608 #endif
609 {
610 if (row != NULL)
611 png_combine_row(png_ptr, row, -1/*ignored*/);
612
613 if (dsp_row != NULL)
614 png_combine_row(png_ptr, dsp_row, -1/*ignored*/);
615 }
616 png_read_finish_row(png_ptr);
617
618 if (png_ptr->read_row_fn != NULL)
619 (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
620
621 }
622 #endif /* SEQUENTIAL_READ */
623
624 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
625 /* Read one or more rows of image data. If the image is interlaced,
626 * and png_set_interlace_handling() has been called, the rows need to
627 * contain the contents of the rows from the previous pass. If the
628 * image has alpha or transparency, and png_handle_alpha()[*] has been
629 * called, the rows contents must be initialized to the contents of the
630 * screen.
631 *
632 * "row" holds the actual image, and pixels are placed in it
633 * as they arrive. If the image is displayed after each pass, it will
634 * appear to "sparkle" in. "display_row" can be used to display a
635 * "chunky" progressive image, with finer detail added as it becomes
636 * available. If you do not want this "chunky" display, you may pass
637 * NULL for display_row. If you do not want the sparkle display, and
638 * you have not called png_handle_alpha(), you may pass NULL for rows.
639 * If you have called png_handle_alpha(), and the image has either an
640 * alpha channel or a transparency chunk, you must provide a buffer for
641 * rows. In this case, you do not have to provide a display_row buffer
642 * also, but you may. If the image is not interlaced, or if you have
643 * not called png_set_interlace_handling(), the display_row buffer will
644 * be ignored, so pass NULL to it.
645 *
646 * [*] png_handle_alpha() does not exist yet, as of this version of libpng
647 */
648
649 void PNGAPI
png_read_rows(png_structrp png_ptr,png_bytepp row,png_bytepp display_row,png_uint_32 num_rows)650 png_read_rows(png_structrp png_ptr, png_bytepp row,
651 png_bytepp display_row, png_uint_32 num_rows)
652 {
653 png_uint_32 i;
654 png_bytepp rp;
655 png_bytepp dp;
656
657 png_debug(1, "in png_read_rows");
658
659 if (png_ptr == NULL)
660 return;
661
662 rp = row;
663 dp = display_row;
664 if (rp != NULL && dp != NULL)
665 for (i = 0; i < num_rows; i++)
666 {
667 png_bytep rptr = *rp++;
668 png_bytep dptr = *dp++;
669
670 png_read_row(png_ptr, rptr, dptr);
671 }
672
673 else if (rp != NULL)
674 for (i = 0; i < num_rows; i++)
675 {
676 png_bytep rptr = *rp;
677 png_read_row(png_ptr, rptr, NULL);
678 rp++;
679 }
680
681 else if (dp != NULL)
682 for (i = 0; i < num_rows; i++)
683 {
684 png_bytep dptr = *dp;
685 png_read_row(png_ptr, NULL, dptr);
686 dp++;
687 }
688 }
689 #endif /* SEQUENTIAL_READ */
690
691 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
692
693 #ifdef PNG_MULTY_LINE_ENABLE
694 // OH ISSUE: png optimize
png_read_two_rows(png_structrp png_ptr,png_bytepp rows,png_uint_32 i,png_row_info row_info)695 static void png_read_two_rows(png_structrp png_ptr, png_bytepp rows, png_uint_32 i,
696 png_row_info row_info)
697 {
698 png_debug1(1, "in png_read_two_rows %d", png_ptr->row_buf[0]);
699 png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
700 png_ptr->prev_row + 1, png_ptr->row_buf[0] + 4); // 4 is the increment of x2_filter
701
702 #ifdef PNG_MNG_FEATURES_SUPPORTED
703 if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
704 (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
705 {
706 /* Intrapixel differencing */
707 png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1);
708 }
709 #endif
710
711 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
712 if (png_ptr->transformations
713 # ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
714 || png_ptr->num_palette_max >= 0
715 # endif
716 )
717 png_do_read_transformations(png_ptr, &row_info);
718 #endif
719
720 /* The transformed pixel depth should match the depth now in row_info. */
721 if (png_ptr->transformed_pixel_depth == 0)
722 {
723 png_ptr->transformed_pixel_depth = row_info.pixel_depth;
724 if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
725 png_error(png_ptr, "sequential row overflow");
726 }
727
728 else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
729 png_error(png_ptr, "internal sequential row size calculation error");
730
731 if (rows[i] != NULL)
732 png_combine_row(png_ptr, rows[i], -1);
733
734 png_read_finish_row(png_ptr);
735
736 if (png_ptr->read_row_fn != NULL)
737 (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
738
739 png_ptr->row_buf = png_ptr->row_buf + row_info.rowbytes + 1;
740
741 // do again next line
742 memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
743
744 #ifdef PNG_MNG_FEATURES_SUPPORTED
745 if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
746 (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
747 {
748 /* Intrapixel differencing */
749 png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1);
750 }
751 #endif
752
753 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
754 if (png_ptr->transformations
755 # ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
756 || png_ptr->num_palette_max >= 0
757 # endif
758 )
759 png_do_read_transformations(png_ptr, &row_info);
760 #endif
761
762 /* The transformed pixel depth should match the depth now in row_info. */
763 if (png_ptr->transformed_pixel_depth == 0)
764 {
765 png_ptr->transformed_pixel_depth = row_info.pixel_depth;
766 if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
767 png_error(png_ptr, "sequential row overflow");
768 }
769
770 else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
771 png_error(png_ptr, "internal sequential row size calculation error");
772
773 if (rows[i+1] != NULL)
774 png_combine_row(png_ptr, rows[i+1], -1);
775
776 png_read_finish_row(png_ptr);
777
778 if (png_ptr->read_row_fn != NULL)
779 (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
780
781 png_ptr->row_buf = png_ptr->row_buf + row_info.rowbytes + 1;
782 }
783
png_read_muilty_rows(png_structrp png_ptr,png_bytepp rows,png_uint_32 row_num,png_row_info row_info_in)784 static void png_read_muilty_rows(png_structrp png_ptr, png_bytepp rows,
785 png_uint_32 row_num, png_row_info row_info_in)
786 {
787 if (png_ptr == NULL)
788 return;
789
790 png_debug2(1, "in png_read_muilty_rows (row %lu, pass %d)",
791 (unsigned long)png_ptr->row_number, png_ptr->pass);
792
793 if ((png_ptr->mode & PNG_HAVE_IDAT) == 0)
794 png_error(png_ptr, "Invalid attempt to read row data");
795
796 /* Fill the row with IDAT data: */
797 uInt row_bytes = row_info_in.rowbytes;
798 png_ptr->row_buf[0]=255; /* 255 to force error if no data was found */
799 png_read_IDAT_data(png_ptr, png_ptr->row_buf, (row_bytes + 1) * row_num);
800 png_bytep temp_row = png_ptr->row_buf;
801
802 for (png_uint_32 i = 0; i < row_num; i++) {
803 png_row_info row_info = row_info_in;
804 // check if the x2_filter is effective: only supports channels 3 or 4
805 if ((row_info_in.channels == 3 || row_info_in.channels == 4) &&
806 i < row_num -1 && png_ptr->row_buf[0] > PNG_FILTER_VALUE_SUB &&
807 png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST &&
808 png_ptr->row_buf[0] == png_ptr->row_buf[row_info_in.rowbytes + 1])
809 {
810 png_read_two_rows(png_ptr, rows, i, row_info);
811 i++;
812 continue;
813 }
814 if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
815 {
816 if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
817 png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
818 png_ptr->prev_row + 1, png_ptr->row_buf[0]);
819 else
820 png_debug1(1, "bad adaptive filter value %d", png_ptr->row_buf[0]);
821 }
822
823 memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info_in.rowbytes + 1);
824
825 #ifdef PNG_MNG_FEATURES_SUPPORTED
826 if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
827 (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
828 {
829 /* Intrapixel differencing */
830 png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1);
831 }
832 #endif
833
834 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
835 if (png_ptr->transformations
836 # ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
837 || png_ptr->num_palette_max >= 0
838 # endif
839 )
840 png_do_read_transformations(png_ptr, &row_info);
841 #endif
842
843 /* The transformed pixel depth should match the depth now in row_info. */
844 if (png_ptr->transformed_pixel_depth == 0)
845 {
846 png_ptr->transformed_pixel_depth = row_info.pixel_depth;
847 if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
848 png_error(png_ptr, "sequential row overflow");
849 }
850
851 else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
852 png_error(png_ptr, "internal sequential row size calculation error");
853
854 if (rows[i] != NULL)
855 png_combine_row(png_ptr, rows[i], -1);
856
857 png_read_finish_row(png_ptr);
858
859 if (png_ptr->read_row_fn != NULL)
860 (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
861
862 png_ptr->row_buf = png_ptr->row_buf + row_bytes + 1;
863 }
864 png_ptr->row_buf = temp_row;
865 }
866
png_warn_check(png_structrp png_ptr)867 static void png_warn_check(png_structrp png_ptr)
868 {
869 #ifdef PNG_WARNINGS_SUPPORTED
870 /* Check for transforms that have been set but were defined out */
871 #if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED)
872 if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
873 png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined");
874 #endif
875
876 #if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED)
877 if ((png_ptr->transformations & PNG_FILLER) != 0)
878 png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined");
879 #endif
880
881 #if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
882 !defined(PNG_READ_PACKSWAP_SUPPORTED)
883 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
884 png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined");
885 #endif
886
887 #if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED)
888 if ((png_ptr->transformations & PNG_PACK) != 0)
889 png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined");
890 #endif
891
892 #if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED)
893 if ((png_ptr->transformations & PNG_SHIFT) != 0)
894 png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined");
895 #endif
896
897 #if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED)
898 if ((png_ptr->transformations & PNG_BGR) != 0)
899 png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined");
900 #endif
901
902 #if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED)
903 if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
904 png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined");
905 #endif
906 #endif /* WARNINGS */
907 }
908 #endif // PNG_MULTY_LINE_ENABLE
909
910 /* Read the entire image. If the image has an alpha channel or a tRNS
911 * chunk, and you have called png_handle_alpha()[*], you will need to
912 * initialize the image to the current image that PNG will be overlaying.
913 * We set the num_rows again here, in case it was incorrectly set in
914 * png_read_start_row() by a call to png_read_update_info() or
915 * png_start_read_image() if png_set_interlace_handling() wasn't called
916 * prior to either of these functions like it should have been. You can
917 * only call this function once. If you desire to have an image for
918 * each pass of a interlaced image, use png_read_rows() instead.
919 *
920 * [*] png_handle_alpha() does not exist yet, as of this version of libpng
921 */
922 void PNGAPI
png_read_image(png_structrp png_ptr,png_bytepp image)923 png_read_image(png_structrp png_ptr, png_bytepp image)
924 {
925 png_uint_32 i, image_height;
926 int pass, j;
927 png_bytepp rp;
928
929 png_debug(1, "in png_read_image");
930
931 if (png_ptr == NULL)
932 return;
933
934 #ifdef PNG_READ_INTERLACING_SUPPORTED
935 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
936 {
937 pass = png_set_interlace_handling(png_ptr);
938 /* And make sure transforms are initialized. */
939 png_start_read_image(png_ptr);
940 }
941 else
942 {
943 if (png_ptr->interlaced != 0 &&
944 (png_ptr->transformations & PNG_INTERLACE) == 0)
945 {
946 /* Caller called png_start_read_image or png_read_update_info without
947 * first turning on the PNG_INTERLACE transform. We can fix this here,
948 * but the caller should do it!
949 */
950 png_warning(png_ptr, "Interlace handling should be turned on when "
951 "using png_read_image");
952 /* Make sure this is set correctly */
953 png_ptr->num_rows = png_ptr->height;
954 }
955
956 /* Obtain the pass number, which also turns on the PNG_INTERLACE flag in
957 * the above error case.
958 */
959 pass = png_set_interlace_handling(png_ptr);
960 }
961 #else
962 if (png_ptr->interlaced)
963 png_error(png_ptr,
964 "Cannot read interlaced image -- interlace handler disabled");
965
966 pass = 1;
967 #endif
968
969 image_height=png_ptr->height;
970
971 #ifdef PNG_MULTY_LINE_ENABLE
972 // OH ISSUE: png optimize
973 if (png_ptr->interlaced == 0 && png_ptr->bit_depth == 8 && // 8 is 1 pixel 8 bytes
974 (png_ptr->transformations & PNG_CHECK) == 0) {
975 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
976 png_read_start_row(png_ptr);
977
978 png_warn_check(png_ptr);
979 png_row_info row_info;
980 row_info.width = png_ptr->iwidth;
981 row_info.color_type = png_ptr->color_type;
982 row_info.bit_depth = png_ptr->bit_depth;
983 row_info.channels = png_ptr->channels;
984 row_info.pixel_depth = png_ptr->pixel_depth;
985 row_info.rowbytes = png_ptr->rowbytes;
986
987 rp = image;
988 int row_num = PNG_INFLATE_ROWS;
989 for (i = 0; i < image_height; i += PNG_INFLATE_ROWS)
990 {
991 if (image_height - i < PNG_INFLATE_ROWS)
992 {
993 row_num = image_height - i;
994 }
995 png_read_muilty_rows(png_ptr, rp, row_num, row_info);
996 rp += row_num;
997 }
998 }
999 else
1000 #endif
1001 {
1002 for (j = 0; j < pass; j++)
1003 {
1004 rp = image;
1005 for (i = 0; i < image_height; i++)
1006 {
1007 png_read_row(png_ptr, *rp, NULL);
1008 rp++;
1009 }
1010 }
1011 }
1012 }
1013 #endif /* SEQUENTIAL_READ */
1014
1015 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1016 /* Read the end of the PNG file. Will not read past the end of the
1017 * file, will verify the end is accurate, and will read any comments
1018 * or time information at the end of the file, if info is not NULL.
1019 */
1020 void PNGAPI
png_read_end(png_structrp png_ptr,png_inforp info_ptr)1021 png_read_end(png_structrp png_ptr, png_inforp info_ptr)
1022 {
1023 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
1024 int keep;
1025 #endif
1026
1027 png_debug(1, "in png_read_end");
1028
1029 if (png_ptr == NULL)
1030 return;
1031
1032 /* If png_read_end is called in the middle of reading the rows there may
1033 * still be pending IDAT data and an owned zstream. Deal with this here.
1034 */
1035 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
1036 if (png_chunk_unknown_handling(png_ptr, png_IDAT) == 0)
1037 #endif
1038 png_read_finish_IDAT(png_ptr);
1039
1040 #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
1041 /* Report invalid palette index; added at libng-1.5.10 */
1042 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
1043 png_ptr->num_palette_max > png_ptr->num_palette)
1044 png_benign_error(png_ptr, "Read palette index exceeding num_palette");
1045 #endif
1046
1047 do
1048 {
1049 png_uint_32 length = png_read_chunk_header(png_ptr);
1050 png_uint_32 chunk_name = png_ptr->chunk_name;
1051
1052 if (chunk_name != png_IDAT)
1053 png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
1054
1055 if (chunk_name == png_IEND)
1056 png_handle_IEND(png_ptr, info_ptr, length);
1057
1058 else if (chunk_name == png_IHDR)
1059 png_handle_IHDR(png_ptr, info_ptr, length);
1060
1061 else if (info_ptr == NULL)
1062 png_crc_finish(png_ptr, length);
1063
1064 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
1065 else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
1066 {
1067 if (chunk_name == png_IDAT)
1068 {
1069 if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
1070 || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
1071 png_benign_error(png_ptr, ".Too many IDATs found");
1072 }
1073 png_handle_unknown(png_ptr, info_ptr, length, keep);
1074 if (chunk_name == png_PLTE)
1075 png_ptr->mode |= PNG_HAVE_PLTE;
1076 }
1077 #endif
1078
1079 else if (chunk_name == png_IDAT)
1080 {
1081 /* Zero length IDATs are legal after the last IDAT has been
1082 * read, but not after other chunks have been read. 1.6 does not
1083 * always read all the deflate data; specifically it cannot be relied
1084 * upon to read the Adler32 at the end. If it doesn't ignore IDAT
1085 * chunks which are longer than zero as well:
1086 */
1087 if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
1088 || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
1089 png_benign_error(png_ptr, "..Too many IDATs found");
1090
1091 png_crc_finish(png_ptr, length);
1092 }
1093 else if (chunk_name == png_PLTE)
1094 png_handle_PLTE(png_ptr, info_ptr, length);
1095
1096 #ifdef PNG_READ_bKGD_SUPPORTED
1097 else if (chunk_name == png_bKGD)
1098 png_handle_bKGD(png_ptr, info_ptr, length);
1099 #endif
1100
1101 #ifdef PNG_READ_cHRM_SUPPORTED
1102 else if (chunk_name == png_cHRM)
1103 png_handle_cHRM(png_ptr, info_ptr, length);
1104 #endif
1105
1106 #ifdef PNG_READ_eXIf_SUPPORTED
1107 else if (chunk_name == png_eXIf)
1108 png_handle_eXIf(png_ptr, info_ptr, length);
1109 #endif
1110
1111 #ifdef PNG_READ_gAMA_SUPPORTED
1112 else if (chunk_name == png_gAMA)
1113 png_handle_gAMA(png_ptr, info_ptr, length);
1114 #endif
1115
1116 #ifdef PNG_READ_hIST_SUPPORTED
1117 else if (chunk_name == png_hIST)
1118 png_handle_hIST(png_ptr, info_ptr, length);
1119 #endif
1120
1121 #ifdef PNG_READ_oFFs_SUPPORTED
1122 else if (chunk_name == png_oFFs)
1123 png_handle_oFFs(png_ptr, info_ptr, length);
1124 #endif
1125
1126 #ifdef PNG_READ_pCAL_SUPPORTED
1127 else if (chunk_name == png_pCAL)
1128 png_handle_pCAL(png_ptr, info_ptr, length);
1129 #endif
1130
1131 #ifdef PNG_READ_sCAL_SUPPORTED
1132 else if (chunk_name == png_sCAL)
1133 png_handle_sCAL(png_ptr, info_ptr, length);
1134 #endif
1135
1136 #ifdef PNG_READ_pHYs_SUPPORTED
1137 else if (chunk_name == png_pHYs)
1138 png_handle_pHYs(png_ptr, info_ptr, length);
1139 #endif
1140
1141 #ifdef PNG_READ_sBIT_SUPPORTED
1142 else if (chunk_name == png_sBIT)
1143 png_handle_sBIT(png_ptr, info_ptr, length);
1144 #endif
1145
1146 #ifdef PNG_READ_sRGB_SUPPORTED
1147 else if (chunk_name == png_sRGB)
1148 png_handle_sRGB(png_ptr, info_ptr, length);
1149 #endif
1150
1151 #ifdef PNG_READ_iCCP_SUPPORTED
1152 else if (chunk_name == png_iCCP)
1153 png_handle_iCCP(png_ptr, info_ptr, length);
1154 #endif
1155
1156 #ifdef PNG_READ_sPLT_SUPPORTED
1157 else if (chunk_name == png_sPLT)
1158 png_handle_sPLT(png_ptr, info_ptr, length);
1159 #endif
1160
1161 #ifdef PNG_READ_tEXt_SUPPORTED
1162 else if (chunk_name == png_tEXt)
1163 png_handle_tEXt(png_ptr, info_ptr, length);
1164 #endif
1165
1166 #ifdef PNG_READ_tIME_SUPPORTED
1167 else if (chunk_name == png_tIME)
1168 png_handle_tIME(png_ptr, info_ptr, length);
1169 #endif
1170
1171 #ifdef PNG_READ_tRNS_SUPPORTED
1172 else if (chunk_name == png_tRNS)
1173 png_handle_tRNS(png_ptr, info_ptr, length);
1174 #endif
1175
1176 #ifdef PNG_READ_zTXt_SUPPORTED
1177 else if (chunk_name == png_zTXt)
1178 png_handle_zTXt(png_ptr, info_ptr, length);
1179 #endif
1180
1181 #ifdef PNG_READ_iTXt_SUPPORTED
1182 else if (chunk_name == png_iTXt)
1183 png_handle_iTXt(png_ptr, info_ptr, length);
1184 #endif
1185
1186 else
1187 png_handle_unknown(png_ptr, info_ptr, length,
1188 PNG_HANDLE_CHUNK_AS_DEFAULT);
1189 } while ((png_ptr->mode & PNG_HAVE_IEND) == 0);
1190 }
1191 #endif /* SEQUENTIAL_READ */
1192
1193 /* Free all memory used in the read struct */
1194 static void
png_read_destroy(png_structrp png_ptr)1195 png_read_destroy(png_structrp png_ptr)
1196 {
1197 png_debug(1, "in png_read_destroy");
1198
1199 #ifdef PNG_READ_GAMMA_SUPPORTED
1200 png_destroy_gamma_table(png_ptr);
1201 #endif
1202
1203 png_free(png_ptr, png_ptr->big_row_buf);
1204 png_ptr->big_row_buf = NULL;
1205 png_free(png_ptr, png_ptr->big_prev_row);
1206 png_ptr->big_prev_row = NULL;
1207 png_free(png_ptr, png_ptr->read_buffer);
1208 png_ptr->read_buffer = NULL;
1209
1210 #ifdef PNG_READ_QUANTIZE_SUPPORTED
1211 png_free(png_ptr, png_ptr->palette_lookup);
1212 png_ptr->palette_lookup = NULL;
1213 png_free(png_ptr, png_ptr->quantize_index);
1214 png_ptr->quantize_index = NULL;
1215 #endif
1216
1217 if ((png_ptr->free_me & PNG_FREE_PLTE) != 0)
1218 {
1219 png_zfree(png_ptr, png_ptr->palette);
1220 png_ptr->palette = NULL;
1221 }
1222 png_ptr->free_me &= ~PNG_FREE_PLTE;
1223
1224 #if defined(PNG_tRNS_SUPPORTED) || \
1225 defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
1226 if ((png_ptr->free_me & PNG_FREE_TRNS) != 0)
1227 {
1228 png_free(png_ptr, png_ptr->trans_alpha);
1229 png_ptr->trans_alpha = NULL;
1230 }
1231 png_ptr->free_me &= ~PNG_FREE_TRNS;
1232 #endif
1233
1234 inflateEnd(&png_ptr->zstream);
1235
1236 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
1237 png_free(png_ptr, png_ptr->save_buffer);
1238 png_ptr->save_buffer = NULL;
1239 #endif
1240
1241 #if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) && \
1242 defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
1243 png_free(png_ptr, png_ptr->unknown_chunk.data);
1244 png_ptr->unknown_chunk.data = NULL;
1245 #endif
1246
1247 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
1248 png_free(png_ptr, png_ptr->chunk_list);
1249 png_ptr->chunk_list = NULL;
1250 #endif
1251
1252 #if defined(PNG_READ_EXPAND_SUPPORTED) && \
1253 defined(PNG_ARM_NEON_IMPLEMENTATION)
1254 png_free(png_ptr, png_ptr->riffled_palette);
1255 png_ptr->riffled_palette = NULL;
1256 #endif
1257
1258 /* NOTE: the 'setjmp' buffer may still be allocated and the memory and error
1259 * callbacks are still set at this point. They are required to complete the
1260 * destruction of the png_struct itself.
1261 */
1262 }
1263
1264 /* Free all memory used by the read */
1265 void PNGAPI
png_destroy_read_struct(png_structpp png_ptr_ptr,png_infopp info_ptr_ptr,png_infopp end_info_ptr_ptr)1266 png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
1267 png_infopp end_info_ptr_ptr)
1268 {
1269 png_structrp png_ptr = NULL;
1270
1271 png_debug(1, "in png_destroy_read_struct");
1272
1273 if (png_ptr_ptr != NULL)
1274 png_ptr = *png_ptr_ptr;
1275
1276 if (png_ptr == NULL)
1277 return;
1278
1279 /* libpng 1.6.0: use the API to destroy info structs to ensure consistent
1280 * behavior. Prior to 1.6.0 libpng did extra 'info' destruction in this API.
1281 * The extra was, apparently, unnecessary yet this hides memory leak bugs.
1282 */
1283 png_destroy_info_struct(png_ptr, end_info_ptr_ptr);
1284 png_destroy_info_struct(png_ptr, info_ptr_ptr);
1285
1286 *png_ptr_ptr = NULL;
1287 png_read_destroy(png_ptr);
1288 png_destroy_png_struct(png_ptr);
1289 }
1290
1291 void PNGAPI
png_set_read_status_fn(png_structrp png_ptr,png_read_status_ptr read_row_fn)1292 png_set_read_status_fn(png_structrp png_ptr, png_read_status_ptr read_row_fn)
1293 {
1294 if (png_ptr == NULL)
1295 return;
1296
1297 png_ptr->read_row_fn = read_row_fn;
1298 }
1299
1300
1301 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1302 #ifdef PNG_INFO_IMAGE_SUPPORTED
1303 void PNGAPI
png_read_png(png_structrp png_ptr,png_inforp info_ptr,int transforms,voidp params)1304 png_read_png(png_structrp png_ptr, png_inforp info_ptr,
1305 int transforms, voidp params)
1306 {
1307 if (png_ptr == NULL || info_ptr == NULL)
1308 return;
1309
1310 /* png_read_info() gives us all of the information from the
1311 * PNG file before the first IDAT (image data chunk).
1312 */
1313 png_read_info(png_ptr, info_ptr);
1314 if (info_ptr->height > PNG_UINT_32_MAX/(sizeof (png_bytep)))
1315 png_error(png_ptr, "Image is too high to process with png_read_png()");
1316
1317 /* -------------- image transformations start here ------------------- */
1318 /* libpng 1.6.10: add code to cause a png_app_error if a selected TRANSFORM
1319 * is not implemented. This will only happen in de-configured (non-default)
1320 * libpng builds. The results can be unexpected - png_read_png may return
1321 * short or mal-formed rows because the transform is skipped.
1322 */
1323
1324 /* Tell libpng to strip 16-bit/color files down to 8 bits per color.
1325 */
1326 if ((transforms & PNG_TRANSFORM_SCALE_16) != 0)
1327 /* Added at libpng-1.5.4. "strip_16" produces the same result that it
1328 * did in earlier versions, while "scale_16" is now more accurate.
1329 */
1330 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1331 png_set_scale_16(png_ptr);
1332 #else
1333 png_app_error(png_ptr, "PNG_TRANSFORM_SCALE_16 not supported");
1334 #endif
1335
1336 /* If both SCALE and STRIP are required pngrtran will effectively cancel the
1337 * latter by doing SCALE first. This is ok and allows apps not to check for
1338 * which is supported to get the right answer.
1339 */
1340 if ((transforms & PNG_TRANSFORM_STRIP_16) != 0)
1341 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1342 png_set_strip_16(png_ptr);
1343 #else
1344 png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_16 not supported");
1345 #endif
1346
1347 /* Strip alpha bytes from the input data without combining with
1348 * the background (not recommended).
1349 */
1350 if ((transforms & PNG_TRANSFORM_STRIP_ALPHA) != 0)
1351 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1352 png_set_strip_alpha(png_ptr);
1353 #else
1354 png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_ALPHA not supported");
1355 #endif
1356
1357 /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single
1358 * byte into separate bytes (useful for paletted and grayscale images).
1359 */
1360 if ((transforms & PNG_TRANSFORM_PACKING) != 0)
1361 #ifdef PNG_READ_PACK_SUPPORTED
1362 png_set_packing(png_ptr);
1363 #else
1364 png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported");
1365 #endif
1366
1367 /* Change the order of packed pixels to least significant bit first
1368 * (not useful if you are using png_set_packing).
1369 */
1370 if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0)
1371 #ifdef PNG_READ_PACKSWAP_SUPPORTED
1372 png_set_packswap(png_ptr);
1373 #else
1374 png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported");
1375 #endif
1376
1377 /* Expand paletted colors into true RGB triplets
1378 * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel
1379 * Expand paletted or RGB images with transparency to full alpha
1380 * channels so the data will be available as RGBA quartets.
1381 */
1382 if ((transforms & PNG_TRANSFORM_EXPAND) != 0)
1383 #ifdef PNG_READ_EXPAND_SUPPORTED
1384 png_set_expand(png_ptr);
1385 #else
1386 png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND not supported");
1387 #endif
1388
1389 /* We don't handle background color or gamma transformation or quantizing.
1390 */
1391
1392 /* Invert monochrome files to have 0 as white and 1 as black
1393 */
1394 if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0)
1395 #ifdef PNG_READ_INVERT_SUPPORTED
1396 png_set_invert_mono(png_ptr);
1397 #else
1398 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
1399 #endif
1400
1401 /* If you want to shift the pixel values from the range [0,255] or
1402 * [0,65535] to the original [0,7] or [0,31], or whatever range the
1403 * colors were originally in:
1404 */
1405 if ((transforms & PNG_TRANSFORM_SHIFT) != 0)
1406 #ifdef PNG_READ_SHIFT_SUPPORTED
1407 if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
1408 png_set_shift(png_ptr, &info_ptr->sig_bit);
1409 #else
1410 png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
1411 #endif
1412
1413 /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
1414 if ((transforms & PNG_TRANSFORM_BGR) != 0)
1415 #ifdef PNG_READ_BGR_SUPPORTED
1416 png_set_bgr(png_ptr);
1417 #else
1418 png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported");
1419 #endif
1420
1421 /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
1422 if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0)
1423 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
1424 png_set_swap_alpha(png_ptr);
1425 #else
1426 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported");
1427 #endif
1428
1429 /* Swap bytes of 16-bit files to least significant byte first */
1430 if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0)
1431 #ifdef PNG_READ_SWAP_SUPPORTED
1432 png_set_swap(png_ptr);
1433 #else
1434 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
1435 #endif
1436
1437 /* Added at libpng-1.2.41 */
1438 /* Invert the alpha channel from opacity to transparency */
1439 if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0)
1440 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1441 png_set_invert_alpha(png_ptr);
1442 #else
1443 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported");
1444 #endif
1445
1446 /* Added at libpng-1.2.41 */
1447 /* Expand grayscale image to RGB */
1448 if ((transforms & PNG_TRANSFORM_GRAY_TO_RGB) != 0)
1449 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1450 png_set_gray_to_rgb(png_ptr);
1451 #else
1452 png_app_error(png_ptr, "PNG_TRANSFORM_GRAY_TO_RGB not supported");
1453 #endif
1454
1455 /* Added at libpng-1.5.4 */
1456 if ((transforms & PNG_TRANSFORM_EXPAND_16) != 0)
1457 #ifdef PNG_READ_EXPAND_16_SUPPORTED
1458 png_set_expand_16(png_ptr);
1459 #else
1460 png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND_16 not supported");
1461 #endif
1462
1463 /* We don't handle adding filler bytes */
1464
1465 /* We use png_read_image and rely on that for interlace handling, but we also
1466 * call png_read_update_info therefore must turn on interlace handling now:
1467 */
1468 (void)png_set_interlace_handling(png_ptr);
1469
1470 /* Optional call to gamma correct and add the background to the palette
1471 * and update info structure. REQUIRED if you are expecting libpng to
1472 * update the palette for you (i.e., you selected such a transform above).
1473 */
1474 png_read_update_info(png_ptr, info_ptr);
1475
1476 /* -------------- image transformations end here ------------------- */
1477
1478 png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);
1479 if (info_ptr->row_pointers == NULL)
1480 {
1481 png_uint_32 iptr;
1482
1483 info_ptr->row_pointers = png_voidcast(png_bytepp, png_malloc(png_ptr,
1484 info_ptr->height * (sizeof (png_bytep))));
1485
1486 for (iptr=0; iptr<info_ptr->height; iptr++)
1487 info_ptr->row_pointers[iptr] = NULL;
1488
1489 info_ptr->free_me |= PNG_FREE_ROWS;
1490
1491 for (iptr = 0; iptr < info_ptr->height; iptr++)
1492 info_ptr->row_pointers[iptr] = png_voidcast(png_bytep,
1493 png_malloc(png_ptr, info_ptr->rowbytes));
1494 }
1495
1496 png_read_image(png_ptr, info_ptr->row_pointers);
1497 info_ptr->valid |= PNG_INFO_IDAT;
1498
1499 /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
1500 png_read_end(png_ptr, info_ptr);
1501
1502 PNG_UNUSED(params)
1503 }
1504 #endif /* INFO_IMAGE */
1505 #endif /* SEQUENTIAL_READ */
1506
1507 #ifdef PNG_SIMPLIFIED_READ_SUPPORTED
1508 /* SIMPLIFIED READ
1509 *
1510 * This code currently relies on the sequential reader, though it could easily
1511 * be made to work with the progressive one.
1512 */
1513 /* Arguments to png_image_finish_read: */
1514
1515 /* Encoding of PNG data (used by the color-map code) */
1516 # define P_NOTSET 0 /* File encoding not yet known */
1517 # define P_sRGB 1 /* 8-bit encoded to sRGB gamma */
1518 # define P_LINEAR 2 /* 16-bit linear: not encoded, NOT pre-multiplied! */
1519 # define P_FILE 3 /* 8-bit encoded to file gamma, not sRGB or linear */
1520 # define P_LINEAR8 4 /* 8-bit linear: only from a file value */
1521
1522 /* Color-map processing: after libpng has run on the PNG image further
1523 * processing may be needed to convert the data to color-map indices.
1524 */
1525 #define PNG_CMAP_NONE 0
1526 #define PNG_CMAP_GA 1 /* Process GA data to a color-map with alpha */
1527 #define PNG_CMAP_TRANS 2 /* Process GA data to a background index */
1528 #define PNG_CMAP_RGB 3 /* Process RGB data */
1529 #define PNG_CMAP_RGB_ALPHA 4 /* Process RGBA data */
1530
1531 /* The following document where the background is for each processing case. */
1532 #define PNG_CMAP_NONE_BACKGROUND 256
1533 #define PNG_CMAP_GA_BACKGROUND 231
1534 #define PNG_CMAP_TRANS_BACKGROUND 254
1535 #define PNG_CMAP_RGB_BACKGROUND 256
1536 #define PNG_CMAP_RGB_ALPHA_BACKGROUND 216
1537
1538 typedef struct
1539 {
1540 /* Arguments: */
1541 png_imagep image;
1542 png_voidp buffer;
1543 png_int_32 row_stride;
1544 png_voidp colormap;
1545 png_const_colorp background;
1546 /* Local variables: */
1547 png_voidp local_row;
1548 png_voidp first_row;
1549 ptrdiff_t row_bytes; /* step between rows */
1550 int file_encoding; /* E_ values above */
1551 png_fixed_point gamma_to_linear; /* For P_FILE, reciprocal of gamma */
1552 int colormap_processing; /* PNG_CMAP_ values above */
1553 } png_image_read_control;
1554
1555 /* Do all the *safe* initialization - 'safe' means that png_error won't be
1556 * called, so setting up the jmp_buf is not required. This means that anything
1557 * called from here must *not* call png_malloc - it has to call png_malloc_warn
1558 * instead so that control is returned safely back to this routine.
1559 */
1560 static int
png_image_read_init(png_imagep image)1561 png_image_read_init(png_imagep image)
1562 {
1563 if (image->opaque == NULL)
1564 {
1565 png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, image,
1566 png_safe_error, png_safe_warning);
1567
1568 /* And set the rest of the structure to NULL to ensure that the various
1569 * fields are consistent.
1570 */
1571 memset(image, 0, (sizeof *image));
1572 image->version = PNG_IMAGE_VERSION;
1573
1574 if (png_ptr != NULL)
1575 {
1576 png_infop info_ptr = png_create_info_struct(png_ptr);
1577
1578 if (info_ptr != NULL)
1579 {
1580 png_controlp control = png_voidcast(png_controlp,
1581 png_malloc_warn(png_ptr, (sizeof *control)));
1582
1583 if (control != NULL)
1584 {
1585 memset(control, 0, (sizeof *control));
1586
1587 control->png_ptr = png_ptr;
1588 control->info_ptr = info_ptr;
1589 control->for_write = 0;
1590
1591 image->opaque = control;
1592 return 1;
1593 }
1594
1595 /* Error clean up */
1596 png_destroy_info_struct(png_ptr, &info_ptr);
1597 }
1598
1599 png_destroy_read_struct(&png_ptr, NULL, NULL);
1600 }
1601
1602 return png_image_error(image, "png_image_read: out of memory");
1603 }
1604
1605 return png_image_error(image, "png_image_read: opaque pointer not NULL");
1606 }
1607
1608 /* Utility to find the base format of a PNG file from a png_struct. */
1609 static png_uint_32
png_image_format(png_structrp png_ptr)1610 png_image_format(png_structrp png_ptr)
1611 {
1612 png_uint_32 format = 0;
1613
1614 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
1615 format |= PNG_FORMAT_FLAG_COLOR;
1616
1617 if ((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
1618 format |= PNG_FORMAT_FLAG_ALPHA;
1619
1620 /* Use png_ptr here, not info_ptr, because by examination png_handle_tRNS
1621 * sets the png_struct fields; that's all we are interested in here. The
1622 * precise interaction with an app call to png_set_tRNS and PNG file reading
1623 * is unclear.
1624 */
1625 else if (png_ptr->num_trans > 0)
1626 format |= PNG_FORMAT_FLAG_ALPHA;
1627
1628 if (png_ptr->bit_depth == 16)
1629 format |= PNG_FORMAT_FLAG_LINEAR;
1630
1631 if ((png_ptr->color_type & PNG_COLOR_MASK_PALETTE) != 0)
1632 format |= PNG_FORMAT_FLAG_COLORMAP;
1633
1634 return format;
1635 }
1636
1637 /* Is the given gamma significantly different from sRGB? The test is the same
1638 * one used in pngrtran.c when deciding whether to do gamma correction. The
1639 * arithmetic optimizes the division by using the fact that the inverse of the
1640 * file sRGB gamma is 2.2
1641 */
1642 static int
png_gamma_not_sRGB(png_fixed_point g)1643 png_gamma_not_sRGB(png_fixed_point g)
1644 {
1645 if (g < PNG_FP_1)
1646 {
1647 /* An uninitialized gamma is assumed to be sRGB for the simplified API. */
1648 if (g == 0)
1649 return 0;
1650
1651 return png_gamma_significant((g * 11 + 2)/5 /* i.e. *2.2, rounded */);
1652 }
1653
1654 return 1;
1655 }
1656
1657 /* Do the main body of a 'png_image_begin_read' function; read the PNG file
1658 * header and fill in all the information. This is executed in a safe context,
1659 * unlike the init routine above.
1660 */
1661 static int
png_image_read_header(png_voidp argument)1662 png_image_read_header(png_voidp argument)
1663 {
1664 png_imagep image = png_voidcast(png_imagep, argument);
1665 png_structrp png_ptr = image->opaque->png_ptr;
1666 png_inforp info_ptr = image->opaque->info_ptr;
1667
1668 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
1669 png_set_benign_errors(png_ptr, 1/*warn*/);
1670 #endif
1671 png_read_info(png_ptr, info_ptr);
1672
1673 /* Do this the fast way; just read directly out of png_struct. */
1674 image->width = png_ptr->width;
1675 image->height = png_ptr->height;
1676
1677 {
1678 png_uint_32 format = png_image_format(png_ptr);
1679
1680 image->format = format;
1681
1682 #ifdef PNG_COLORSPACE_SUPPORTED
1683 /* Does the colorspace match sRGB? If there is no color endpoint
1684 * (colorant) information assume yes, otherwise require the
1685 * 'ENDPOINTS_MATCHP_sRGB' colorspace flag to have been set. If the
1686 * colorspace has been determined to be invalid ignore it.
1687 */
1688 if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && ((png_ptr->colorspace.flags
1689 & (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB|
1690 PNG_COLORSPACE_INVALID)) == PNG_COLORSPACE_HAVE_ENDPOINTS))
1691 image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB;
1692 #endif
1693 }
1694
1695 /* We need the maximum number of entries regardless of the format the
1696 * application sets here.
1697 */
1698 {
1699 png_uint_32 cmap_entries;
1700
1701 switch (png_ptr->color_type)
1702 {
1703 case PNG_COLOR_TYPE_GRAY:
1704 cmap_entries = 1U << png_ptr->bit_depth;
1705 break;
1706
1707 case PNG_COLOR_TYPE_PALETTE:
1708 cmap_entries = (png_uint_32)png_ptr->num_palette;
1709 break;
1710
1711 default:
1712 cmap_entries = 256;
1713 break;
1714 }
1715
1716 if (cmap_entries > 256)
1717 cmap_entries = 256;
1718
1719 image->colormap_entries = cmap_entries;
1720 }
1721
1722 return 1;
1723 }
1724
1725 #ifdef PNG_STDIO_SUPPORTED
1726 int PNGAPI
png_image_begin_read_from_stdio(png_imagep image,FILE * file)1727 png_image_begin_read_from_stdio(png_imagep image, FILE* file)
1728 {
1729 if (image != NULL && image->version == PNG_IMAGE_VERSION)
1730 {
1731 if (file != NULL)
1732 {
1733 if (png_image_read_init(image) != 0)
1734 {
1735 /* This is slightly evil, but png_init_io doesn't do anything other
1736 * than this and we haven't changed the standard IO functions so
1737 * this saves a 'safe' function.
1738 */
1739 image->opaque->png_ptr->io_ptr = file;
1740 return png_safe_execute(image, png_image_read_header, image);
1741 }
1742 }
1743
1744 else
1745 return png_image_error(image,
1746 "png_image_begin_read_from_stdio: invalid argument");
1747 }
1748
1749 else if (image != NULL)
1750 return png_image_error(image,
1751 "png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION");
1752
1753 return 0;
1754 }
1755
1756 int PNGAPI
png_image_begin_read_from_file(png_imagep image,const char * file_name)1757 png_image_begin_read_from_file(png_imagep image, const char *file_name)
1758 {
1759 if (image != NULL && image->version == PNG_IMAGE_VERSION)
1760 {
1761 if (file_name != NULL)
1762 {
1763 FILE *fp = fopen(file_name, "rb");
1764
1765 if (fp != NULL)
1766 {
1767 if (png_image_read_init(image) != 0)
1768 {
1769 image->opaque->png_ptr->io_ptr = fp;
1770 image->opaque->owned_file = 1;
1771 return png_safe_execute(image, png_image_read_header, image);
1772 }
1773
1774 /* Clean up: just the opened file. */
1775 (void)fclose(fp);
1776 }
1777
1778 else
1779 return png_image_error(image, strerror(errno));
1780 }
1781
1782 else
1783 return png_image_error(image,
1784 "png_image_begin_read_from_file: invalid argument");
1785 }
1786
1787 else if (image != NULL)
1788 return png_image_error(image,
1789 "png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION");
1790
1791 return 0;
1792 }
1793 #endif /* STDIO */
1794
1795 static void PNGCBAPI
png_image_memory_read(png_structp png_ptr,png_bytep out,size_t need)1796 png_image_memory_read(png_structp png_ptr, png_bytep out, size_t need)
1797 {
1798 if (png_ptr != NULL)
1799 {
1800 png_imagep image = png_voidcast(png_imagep, png_ptr->io_ptr);
1801 if (image != NULL)
1802 {
1803 png_controlp cp = image->opaque;
1804 if (cp != NULL)
1805 {
1806 png_const_bytep memory = cp->memory;
1807 size_t size = cp->size;
1808
1809 if (memory != NULL && size >= need)
1810 {
1811 memcpy(out, memory, need);
1812 cp->memory = memory + need;
1813 cp->size = size - need;
1814 return;
1815 }
1816
1817 png_error(png_ptr, "read beyond end of data");
1818 }
1819 }
1820
1821 png_error(png_ptr, "invalid memory read");
1822 }
1823 }
1824
png_image_begin_read_from_memory(png_imagep image,png_const_voidp memory,size_t size)1825 int PNGAPI png_image_begin_read_from_memory(png_imagep image,
1826 png_const_voidp memory, size_t size)
1827 {
1828 if (image != NULL && image->version == PNG_IMAGE_VERSION)
1829 {
1830 if (memory != NULL && size > 0)
1831 {
1832 if (png_image_read_init(image) != 0)
1833 {
1834 /* Now set the IO functions to read from the memory buffer and
1835 * store it into io_ptr. Again do this in-place to avoid calling a
1836 * libpng function that requires error handling.
1837 */
1838 image->opaque->memory = png_voidcast(png_const_bytep, memory);
1839 image->opaque->size = size;
1840 image->opaque->png_ptr->io_ptr = image;
1841 image->opaque->png_ptr->read_data_fn = png_image_memory_read;
1842
1843 return png_safe_execute(image, png_image_read_header, image);
1844 }
1845 }
1846
1847 else
1848 return png_image_error(image,
1849 "png_image_begin_read_from_memory: invalid argument");
1850 }
1851
1852 else if (image != NULL)
1853 return png_image_error(image,
1854 "png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION");
1855
1856 return 0;
1857 }
1858
1859 /* Utility function to skip chunks that are not used by the simplified image
1860 * read functions and an appropriate macro to call it.
1861 */
1862 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
1863 static void
png_image_skip_unused_chunks(png_structrp png_ptr)1864 png_image_skip_unused_chunks(png_structrp png_ptr)
1865 {
1866 /* Prepare the reader to ignore all recognized chunks whose data will not
1867 * be used, i.e., all chunks recognized by libpng except for those
1868 * involved in basic image reading:
1869 *
1870 * IHDR, PLTE, IDAT, IEND
1871 *
1872 * Or image data handling:
1873 *
1874 * tRNS, bKGD, gAMA, cHRM, sRGB, [iCCP] and sBIT.
1875 *
1876 * This provides a small performance improvement and eliminates any
1877 * potential vulnerability to security problems in the unused chunks.
1878 *
1879 * At present the iCCP chunk data isn't used, so iCCP chunk can be ignored
1880 * too. This allows the simplified API to be compiled without iCCP support,
1881 * however if the support is there the chunk is still checked to detect
1882 * errors (which are unfortunately quite common.)
1883 */
1884 {
1885 static const png_byte chunks_to_process[] = {
1886 98, 75, 71, 68, '\0', /* bKGD */
1887 99, 72, 82, 77, '\0', /* cHRM */
1888 103, 65, 77, 65, '\0', /* gAMA */
1889 # ifdef PNG_READ_iCCP_SUPPORTED
1890 105, 67, 67, 80, '\0', /* iCCP */
1891 # endif
1892 115, 66, 73, 84, '\0', /* sBIT */
1893 115, 82, 71, 66, '\0', /* sRGB */
1894 };
1895
1896 /* Ignore unknown chunks and all other chunks except for the
1897 * IHDR, PLTE, tRNS, IDAT, and IEND chunks.
1898 */
1899 png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_NEVER,
1900 NULL, -1);
1901
1902 /* But do not ignore image data handling chunks */
1903 png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_AS_DEFAULT,
1904 chunks_to_process, (int)/*SAFE*/(sizeof chunks_to_process)/5);
1905 }
1906 }
1907
1908 # define PNG_SKIP_CHUNKS(p) png_image_skip_unused_chunks(p)
1909 #else
1910 # define PNG_SKIP_CHUNKS(p) ((void)0)
1911 #endif /* HANDLE_AS_UNKNOWN */
1912
1913 /* The following macro gives the exact rounded answer for all values in the
1914 * range 0..255 (it actually divides by 51.2, but the rounding still generates
1915 * the correct numbers 0..5
1916 */
1917 #define PNG_DIV51(v8) (((v8) * 5 + 130) >> 8)
1918
1919 /* Utility functions to make particular color-maps */
1920 static void
set_file_encoding(png_image_read_control * display)1921 set_file_encoding(png_image_read_control *display)
1922 {
1923 png_fixed_point g = display->image->opaque->png_ptr->colorspace.gamma;
1924 if (png_gamma_significant(g) != 0)
1925 {
1926 if (png_gamma_not_sRGB(g) != 0)
1927 {
1928 display->file_encoding = P_FILE;
1929 display->gamma_to_linear = png_reciprocal(g);
1930 }
1931
1932 else
1933 display->file_encoding = P_sRGB;
1934 }
1935
1936 else
1937 display->file_encoding = P_LINEAR8;
1938 }
1939
1940 static unsigned int
decode_gamma(png_image_read_control * display,png_uint_32 value,int encoding)1941 decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding)
1942 {
1943 if (encoding == P_FILE) /* double check */
1944 encoding = display->file_encoding;
1945
1946 if (encoding == P_NOTSET) /* must be the file encoding */
1947 {
1948 set_file_encoding(display);
1949 encoding = display->file_encoding;
1950 }
1951
1952 switch (encoding)
1953 {
1954 case P_FILE:
1955 value = png_gamma_16bit_correct(value*257, display->gamma_to_linear);
1956 break;
1957
1958 case P_sRGB:
1959 value = png_sRGB_table[value];
1960 break;
1961
1962 case P_LINEAR:
1963 break;
1964
1965 case P_LINEAR8:
1966 value *= 257;
1967 break;
1968
1969 #ifdef __GNUC__
1970 default:
1971 png_error(display->image->opaque->png_ptr,
1972 "unexpected encoding (internal error)");
1973 #endif
1974 }
1975
1976 return value;
1977 }
1978
1979 static png_uint_32
png_colormap_compose(png_image_read_control * display,png_uint_32 foreground,int foreground_encoding,png_uint_32 alpha,png_uint_32 background,int encoding)1980 png_colormap_compose(png_image_read_control *display,
1981 png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha,
1982 png_uint_32 background, int encoding)
1983 {
1984 /* The file value is composed on the background, the background has the given
1985 * encoding and so does the result, the file is encoded with P_FILE and the
1986 * file and alpha are 8-bit values. The (output) encoding will always be
1987 * P_LINEAR or P_sRGB.
1988 */
1989 png_uint_32 f = decode_gamma(display, foreground, foreground_encoding);
1990 png_uint_32 b = decode_gamma(display, background, encoding);
1991
1992 /* The alpha is always an 8-bit value (it comes from the palette), the value
1993 * scaled by 255 is what PNG_sRGB_FROM_LINEAR requires.
1994 */
1995 f = f * alpha + b * (255-alpha);
1996
1997 if (encoding == P_LINEAR)
1998 {
1999 /* Scale to 65535; divide by 255, approximately (in fact this is extremely
2000 * accurate, it divides by 255.00000005937181414556, with no overflow.)
2001 */
2002 f *= 257; /* Now scaled by 65535 */
2003 f += f >> 16;
2004 f = (f+32768) >> 16;
2005 }
2006
2007 else /* P_sRGB */
2008 f = PNG_sRGB_FROM_LINEAR(f);
2009
2010 return f;
2011 }
2012
2013 /* NOTE: P_LINEAR values to this routine must be 16-bit, but P_FILE values must
2014 * be 8-bit.
2015 */
2016 static void
png_create_colormap_entry(png_image_read_control * display,png_uint_32 ip,png_uint_32 red,png_uint_32 green,png_uint_32 blue,png_uint_32 alpha,int encoding)2017 png_create_colormap_entry(png_image_read_control *display,
2018 png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue,
2019 png_uint_32 alpha, int encoding)
2020 {
2021 png_imagep image = display->image;
2022 int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
2023 P_LINEAR : P_sRGB;
2024 int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 &&
2025 (red != green || green != blue);
2026
2027 if (ip > 255)
2028 png_error(image->opaque->png_ptr, "color-map index out of range");
2029
2030 /* Update the cache with whether the file gamma is significantly different
2031 * from sRGB.
2032 */
2033 if (encoding == P_FILE)
2034 {
2035 if (display->file_encoding == P_NOTSET)
2036 set_file_encoding(display);
2037
2038 /* Note that the cached value may be P_FILE too, but if it is then the
2039 * gamma_to_linear member has been set.
2040 */
2041 encoding = display->file_encoding;
2042 }
2043
2044 if (encoding == P_FILE)
2045 {
2046 png_fixed_point g = display->gamma_to_linear;
2047
2048 red = png_gamma_16bit_correct(red*257, g);
2049 green = png_gamma_16bit_correct(green*257, g);
2050 blue = png_gamma_16bit_correct(blue*257, g);
2051
2052 if (convert_to_Y != 0 || output_encoding == P_LINEAR)
2053 {
2054 alpha *= 257;
2055 encoding = P_LINEAR;
2056 }
2057
2058 else
2059 {
2060 red = PNG_sRGB_FROM_LINEAR(red * 255);
2061 green = PNG_sRGB_FROM_LINEAR(green * 255);
2062 blue = PNG_sRGB_FROM_LINEAR(blue * 255);
2063 encoding = P_sRGB;
2064 }
2065 }
2066
2067 else if (encoding == P_LINEAR8)
2068 {
2069 /* This encoding occurs quite frequently in test cases because PngSuite
2070 * includes a gAMA 1.0 chunk with most images.
2071 */
2072 red *= 257;
2073 green *= 257;
2074 blue *= 257;
2075 alpha *= 257;
2076 encoding = P_LINEAR;
2077 }
2078
2079 else if (encoding == P_sRGB &&
2080 (convert_to_Y != 0 || output_encoding == P_LINEAR))
2081 {
2082 /* The values are 8-bit sRGB values, but must be converted to 16-bit
2083 * linear.
2084 */
2085 red = png_sRGB_table[red];
2086 green = png_sRGB_table[green];
2087 blue = png_sRGB_table[blue];
2088 alpha *= 257;
2089 encoding = P_LINEAR;
2090 }
2091
2092 /* This is set if the color isn't gray but the output is. */
2093 if (encoding == P_LINEAR)
2094 {
2095 if (convert_to_Y != 0)
2096 {
2097 /* NOTE: these values are copied from png_do_rgb_to_gray */
2098 png_uint_32 y = (png_uint_32)6968 * red + (png_uint_32)23434 * green +
2099 (png_uint_32)2366 * blue;
2100
2101 if (output_encoding == P_LINEAR)
2102 y = (y + 16384) >> 15;
2103
2104 else
2105 {
2106 /* y is scaled by 32768, we need it scaled by 255: */
2107 y = (y + 128) >> 8;
2108 y *= 255;
2109 y = PNG_sRGB_FROM_LINEAR((y + 64) >> 7);
2110 alpha = PNG_DIV257(alpha);
2111 encoding = P_sRGB;
2112 }
2113
2114 blue = red = green = y;
2115 }
2116
2117 else if (output_encoding == P_sRGB)
2118 {
2119 red = PNG_sRGB_FROM_LINEAR(red * 255);
2120 green = PNG_sRGB_FROM_LINEAR(green * 255);
2121 blue = PNG_sRGB_FROM_LINEAR(blue * 255);
2122 alpha = PNG_DIV257(alpha);
2123 encoding = P_sRGB;
2124 }
2125 }
2126
2127 if (encoding != output_encoding)
2128 png_error(image->opaque->png_ptr, "bad encoding (internal error)");
2129
2130 /* Store the value. */
2131 {
2132 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
2133 int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
2134 (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
2135 # else
2136 # define afirst 0
2137 # endif
2138 # ifdef PNG_FORMAT_BGR_SUPPORTED
2139 int bgr = (image->format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
2140 # else
2141 # define bgr 0
2142 # endif
2143
2144 if (output_encoding == P_LINEAR)
2145 {
2146 png_uint_16p entry = png_voidcast(png_uint_16p, display->colormap);
2147
2148 entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
2149
2150 /* The linear 16-bit values must be pre-multiplied by the alpha channel
2151 * value, if less than 65535 (this is, effectively, composite on black
2152 * if the alpha channel is removed.)
2153 */
2154 switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
2155 {
2156 case 4:
2157 entry[afirst ? 0 : 3] = (png_uint_16)alpha;
2158 /* FALLTHROUGH */
2159
2160 case 3:
2161 if (alpha < 65535)
2162 {
2163 if (alpha > 0)
2164 {
2165 blue = (blue * alpha + 32767U)/65535U;
2166 green = (green * alpha + 32767U)/65535U;
2167 red = (red * alpha + 32767U)/65535U;
2168 }
2169
2170 else
2171 red = green = blue = 0;
2172 }
2173 entry[afirst + (2 ^ bgr)] = (png_uint_16)blue;
2174 entry[afirst + 1] = (png_uint_16)green;
2175 entry[afirst + bgr] = (png_uint_16)red;
2176 break;
2177
2178 case 2:
2179 entry[1 ^ afirst] = (png_uint_16)alpha;
2180 /* FALLTHROUGH */
2181
2182 case 1:
2183 if (alpha < 65535)
2184 {
2185 if (alpha > 0)
2186 green = (green * alpha + 32767U)/65535U;
2187
2188 else
2189 green = 0;
2190 }
2191 entry[afirst] = (png_uint_16)green;
2192 break;
2193
2194 default:
2195 break;
2196 }
2197 }
2198
2199 else /* output encoding is P_sRGB */
2200 {
2201 png_bytep entry = png_voidcast(png_bytep, display->colormap);
2202
2203 entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
2204
2205 switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
2206 {
2207 case 4:
2208 entry[afirst ? 0 : 3] = (png_byte)alpha;
2209 /* FALLTHROUGH */
2210 case 3:
2211 entry[afirst + (2 ^ bgr)] = (png_byte)blue;
2212 entry[afirst + 1] = (png_byte)green;
2213 entry[afirst + bgr] = (png_byte)red;
2214 break;
2215
2216 case 2:
2217 entry[1 ^ afirst] = (png_byte)alpha;
2218 /* FALLTHROUGH */
2219 case 1:
2220 entry[afirst] = (png_byte)green;
2221 break;
2222
2223 default:
2224 break;
2225 }
2226 }
2227
2228 # ifdef afirst
2229 # undef afirst
2230 # endif
2231 # ifdef bgr
2232 # undef bgr
2233 # endif
2234 }
2235 }
2236
2237 static int
make_gray_file_colormap(png_image_read_control * display)2238 make_gray_file_colormap(png_image_read_control *display)
2239 {
2240 unsigned int i;
2241
2242 for (i=0; i<256; ++i)
2243 png_create_colormap_entry(display, i, i, i, i, 255, P_FILE);
2244
2245 return (int)i;
2246 }
2247
2248 static int
make_gray_colormap(png_image_read_control * display)2249 make_gray_colormap(png_image_read_control *display)
2250 {
2251 unsigned int i;
2252
2253 for (i=0; i<256; ++i)
2254 png_create_colormap_entry(display, i, i, i, i, 255, P_sRGB);
2255
2256 return (int)i;
2257 }
2258 #define PNG_GRAY_COLORMAP_ENTRIES 256
2259
2260 static int
make_ga_colormap(png_image_read_control * display)2261 make_ga_colormap(png_image_read_control *display)
2262 {
2263 unsigned int i, a;
2264
2265 /* Alpha is retained, the output will be a color-map with entries
2266 * selected by six levels of alpha. One transparent entry, 6 gray
2267 * levels for all the intermediate alpha values, leaving 230 entries
2268 * for the opaque grays. The color-map entries are the six values
2269 * [0..5]*51, the GA processing uses PNG_DIV51(value) to find the
2270 * relevant entry.
2271 *
2272 * if (alpha > 229) // opaque
2273 * {
2274 * // The 231 entries are selected to make the math below work:
2275 * base = 0;
2276 * entry = (231 * gray + 128) >> 8;
2277 * }
2278 * else if (alpha < 26) // transparent
2279 * {
2280 * base = 231;
2281 * entry = 0;
2282 * }
2283 * else // partially opaque
2284 * {
2285 * base = 226 + 6 * PNG_DIV51(alpha);
2286 * entry = PNG_DIV51(gray);
2287 * }
2288 */
2289 i = 0;
2290 while (i < 231)
2291 {
2292 unsigned int gray = (i * 256 + 115) / 231;
2293 png_create_colormap_entry(display, i++, gray, gray, gray, 255, P_sRGB);
2294 }
2295
2296 /* 255 is used here for the component values for consistency with the code
2297 * that undoes premultiplication in pngwrite.c.
2298 */
2299 png_create_colormap_entry(display, i++, 255, 255, 255, 0, P_sRGB);
2300
2301 for (a=1; a<5; ++a)
2302 {
2303 unsigned int g;
2304
2305 for (g=0; g<6; ++g)
2306 png_create_colormap_entry(display, i++, g*51, g*51, g*51, a*51,
2307 P_sRGB);
2308 }
2309
2310 return (int)i;
2311 }
2312
2313 #define PNG_GA_COLORMAP_ENTRIES 256
2314
2315 static int
make_rgb_colormap(png_image_read_control * display)2316 make_rgb_colormap(png_image_read_control *display)
2317 {
2318 unsigned int i, r;
2319
2320 /* Build a 6x6x6 opaque RGB cube */
2321 for (i=r=0; r<6; ++r)
2322 {
2323 unsigned int g;
2324
2325 for (g=0; g<6; ++g)
2326 {
2327 unsigned int b;
2328
2329 for (b=0; b<6; ++b)
2330 png_create_colormap_entry(display, i++, r*51, g*51, b*51, 255,
2331 P_sRGB);
2332 }
2333 }
2334
2335 return (int)i;
2336 }
2337
2338 #define PNG_RGB_COLORMAP_ENTRIES 216
2339
2340 /* Return a palette index to the above palette given three 8-bit sRGB values. */
2341 #define PNG_RGB_INDEX(r,g,b) \
2342 ((png_byte)(6 * (6 * PNG_DIV51(r) + PNG_DIV51(g)) + PNG_DIV51(b)))
2343
2344 static int
png_image_read_colormap(png_voidp argument)2345 png_image_read_colormap(png_voidp argument)
2346 {
2347 png_image_read_control *display =
2348 png_voidcast(png_image_read_control*, argument);
2349 png_imagep image = display->image;
2350
2351 png_structrp png_ptr = image->opaque->png_ptr;
2352 png_uint_32 output_format = image->format;
2353 int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
2354 P_LINEAR : P_sRGB;
2355
2356 unsigned int cmap_entries;
2357 unsigned int output_processing; /* Output processing option */
2358 unsigned int data_encoding = P_NOTSET; /* Encoding libpng must produce */
2359
2360 /* Background information; the background color and the index of this color
2361 * in the color-map if it exists (else 256).
2362 */
2363 unsigned int background_index = 256;
2364 png_uint_32 back_r, back_g, back_b;
2365
2366 /* Flags to accumulate things that need to be done to the input. */
2367 int expand_tRNS = 0;
2368
2369 /* Exclude the NYI feature of compositing onto a color-mapped buffer; it is
2370 * very difficult to do, the results look awful, and it is difficult to see
2371 * what possible use it is because the application can't control the
2372 * color-map.
2373 */
2374 if (((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0 ||
2375 png_ptr->num_trans > 0) /* alpha in input */ &&
2376 ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) /* no alpha in output */)
2377 {
2378 if (output_encoding == P_LINEAR) /* compose on black */
2379 back_b = back_g = back_r = 0;
2380
2381 else if (display->background == NULL /* no way to remove it */)
2382 png_error(png_ptr,
2383 "background color must be supplied to remove alpha/transparency");
2384
2385 /* Get a copy of the background color (this avoids repeating the checks
2386 * below.) The encoding is 8-bit sRGB or 16-bit linear, depending on the
2387 * output format.
2388 */
2389 else
2390 {
2391 back_g = display->background->green;
2392 if ((output_format & PNG_FORMAT_FLAG_COLOR) != 0)
2393 {
2394 back_r = display->background->red;
2395 back_b = display->background->blue;
2396 }
2397 else
2398 back_b = back_r = back_g;
2399 }
2400 }
2401
2402 else if (output_encoding == P_LINEAR)
2403 back_b = back_r = back_g = 65535;
2404
2405 else
2406 back_b = back_r = back_g = 255;
2407
2408 /* Default the input file gamma if required - this is necessary because
2409 * libpng assumes that if no gamma information is present the data is in the
2410 * output format, but the simplified API deduces the gamma from the input
2411 * format.
2412 */
2413 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) == 0)
2414 {
2415 /* Do this directly, not using the png_colorspace functions, to ensure
2416 * that it happens even if the colorspace is invalid (though probably if
2417 * it is the setting will be ignored) Note that the same thing can be
2418 * achieved at the application interface with png_set_gAMA.
2419 */
2420 if (png_ptr->bit_depth == 16 &&
2421 (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
2422 png_ptr->colorspace.gamma = PNG_GAMMA_LINEAR;
2423
2424 else
2425 png_ptr->colorspace.gamma = PNG_GAMMA_sRGB_INVERSE;
2426
2427 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
2428 }
2429
2430 /* Decide what to do based on the PNG color type of the input data. The
2431 * utility function png_create_colormap_entry deals with most aspects of the
2432 * output transformations; this code works out how to produce bytes of
2433 * color-map entries from the original format.
2434 */
2435 switch (png_ptr->color_type)
2436 {
2437 case PNG_COLOR_TYPE_GRAY:
2438 if (png_ptr->bit_depth <= 8)
2439 {
2440 /* There at most 256 colors in the output, regardless of
2441 * transparency.
2442 */
2443 unsigned int step, i, val, trans = 256/*ignore*/, back_alpha = 0;
2444
2445 cmap_entries = 1U << png_ptr->bit_depth;
2446 if (cmap_entries > image->colormap_entries)
2447 png_error(png_ptr, "gray[8] color-map: too few entries");
2448
2449 step = 255 / (cmap_entries - 1);
2450 output_processing = PNG_CMAP_NONE;
2451
2452 /* If there is a tRNS chunk then this either selects a transparent
2453 * value or, if the output has no alpha, the background color.
2454 */
2455 if (png_ptr->num_trans > 0)
2456 {
2457 trans = png_ptr->trans_color.gray;
2458
2459 if ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0)
2460 back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
2461 }
2462
2463 /* png_create_colormap_entry just takes an RGBA and writes the
2464 * corresponding color-map entry using the format from 'image',
2465 * including the required conversion to sRGB or linear as
2466 * appropriate. The input values are always either sRGB (if the
2467 * gamma correction flag is 0) or 0..255 scaled file encoded values
2468 * (if the function must gamma correct them).
2469 */
2470 for (i=val=0; i<cmap_entries; ++i, val += step)
2471 {
2472 /* 'i' is a file value. While this will result in duplicated
2473 * entries for 8-bit non-sRGB encoded files it is necessary to
2474 * have non-gamma corrected values to do tRNS handling.
2475 */
2476 if (i != trans)
2477 png_create_colormap_entry(display, i, val, val, val, 255,
2478 P_FILE/*8-bit with file gamma*/);
2479
2480 /* Else this entry is transparent. The colors don't matter if
2481 * there is an alpha channel (back_alpha == 0), but it does no
2482 * harm to pass them in; the values are not set above so this
2483 * passes in white.
2484 *
2485 * NOTE: this preserves the full precision of the application
2486 * supplied background color when it is used.
2487 */
2488 else
2489 png_create_colormap_entry(display, i, back_r, back_g, back_b,
2490 back_alpha, output_encoding);
2491 }
2492
2493 /* We need libpng to preserve the original encoding. */
2494 data_encoding = P_FILE;
2495
2496 /* The rows from libpng, while technically gray values, are now also
2497 * color-map indices; however, they may need to be expanded to 1
2498 * byte per pixel. This is what png_set_packing does (i.e., it
2499 * unpacks the bit values into bytes.)
2500 */
2501 if (png_ptr->bit_depth < 8)
2502 png_set_packing(png_ptr);
2503 }
2504
2505 else /* bit depth is 16 */
2506 {
2507 /* The 16-bit input values can be converted directly to 8-bit gamma
2508 * encoded values; however, if a tRNS chunk is present 257 color-map
2509 * entries are required. This means that the extra entry requires
2510 * special processing; add an alpha channel, sacrifice gray level
2511 * 254 and convert transparent (alpha==0) entries to that.
2512 *
2513 * Use libpng to chop the data to 8 bits. Convert it to sRGB at the
2514 * same time to minimize quality loss. If a tRNS chunk is present
2515 * this means libpng must handle it too; otherwise it is impossible
2516 * to do the exact match on the 16-bit value.
2517 *
2518 * If the output has no alpha channel *and* the background color is
2519 * gray then it is possible to let libpng handle the substitution by
2520 * ensuring that the corresponding gray level matches the background
2521 * color exactly.
2522 */
2523 data_encoding = P_sRGB;
2524
2525 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2526 png_error(png_ptr, "gray[16] color-map: too few entries");
2527
2528 cmap_entries = (unsigned int)make_gray_colormap(display);
2529
2530 if (png_ptr->num_trans > 0)
2531 {
2532 unsigned int back_alpha;
2533
2534 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2535 back_alpha = 0;
2536
2537 else
2538 {
2539 if (back_r == back_g && back_g == back_b)
2540 {
2541 /* Background is gray; no special processing will be
2542 * required.
2543 */
2544 png_color_16 c;
2545 png_uint_32 gray = back_g;
2546
2547 if (output_encoding == P_LINEAR)
2548 {
2549 gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2550
2551 /* And make sure the corresponding palette entry
2552 * matches.
2553 */
2554 png_create_colormap_entry(display, gray, back_g, back_g,
2555 back_g, 65535, P_LINEAR);
2556 }
2557
2558 /* The background passed to libpng, however, must be the
2559 * sRGB value.
2560 */
2561 c.index = 0; /*unused*/
2562 c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2563
2564 /* NOTE: does this work without expanding tRNS to alpha?
2565 * It should be the color->gray case below apparently
2566 * doesn't.
2567 */
2568 png_set_background_fixed(png_ptr, &c,
2569 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2570 0/*gamma: not used*/);
2571
2572 output_processing = PNG_CMAP_NONE;
2573 break;
2574 }
2575 #ifdef __COVERITY__
2576 /* Coverity claims that output_encoding cannot be 2 (P_LINEAR)
2577 * here.
2578 */
2579 back_alpha = 255;
2580 #else
2581 back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
2582 #endif
2583 }
2584
2585 /* output_processing means that the libpng-processed row will be
2586 * 8-bit GA and it has to be processing to single byte color-map
2587 * values. Entry 254 is replaced by either a completely
2588 * transparent entry or by the background color at full
2589 * precision (and the background color is not a simple gray
2590 * level in this case.)
2591 */
2592 expand_tRNS = 1;
2593 output_processing = PNG_CMAP_TRANS;
2594 background_index = 254;
2595
2596 /* And set (overwrite) color-map entry 254 to the actual
2597 * background color at full precision.
2598 */
2599 png_create_colormap_entry(display, 254, back_r, back_g, back_b,
2600 back_alpha, output_encoding);
2601 }
2602
2603 else
2604 output_processing = PNG_CMAP_NONE;
2605 }
2606 break;
2607
2608 case PNG_COLOR_TYPE_GRAY_ALPHA:
2609 /* 8-bit or 16-bit PNG with two channels - gray and alpha. A minimum
2610 * of 65536 combinations. If, however, the alpha channel is to be
2611 * removed there are only 256 possibilities if the background is gray.
2612 * (Otherwise there is a subset of the 65536 possibilities defined by
2613 * the triangle between black, white and the background color.)
2614 *
2615 * Reduce 16-bit files to 8-bit and sRGB encode the result. No need to
2616 * worry about tRNS matching - tRNS is ignored if there is an alpha
2617 * channel.
2618 */
2619 data_encoding = P_sRGB;
2620
2621 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2622 {
2623 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2624 png_error(png_ptr, "gray+alpha color-map: too few entries");
2625
2626 cmap_entries = (unsigned int)make_ga_colormap(display);
2627
2628 background_index = PNG_CMAP_GA_BACKGROUND;
2629 output_processing = PNG_CMAP_GA;
2630 }
2631
2632 else /* alpha is removed */
2633 {
2634 /* Alpha must be removed as the PNG data is processed when the
2635 * background is a color because the G and A channels are
2636 * independent and the vector addition (non-parallel vectors) is a
2637 * 2-D problem.
2638 *
2639 * This can be reduced to the same algorithm as above by making a
2640 * colormap containing gray levels (for the opaque grays), a
2641 * background entry (for a transparent pixel) and a set of four six
2642 * level color values, one set for each intermediate alpha value.
2643 * See the comments in make_ga_colormap for how this works in the
2644 * per-pixel processing.
2645 *
2646 * If the background is gray, however, we only need a 256 entry gray
2647 * level color map. It is sufficient to make the entry generated
2648 * for the background color be exactly the color specified.
2649 */
2650 if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0 ||
2651 (back_r == back_g && back_g == back_b))
2652 {
2653 /* Background is gray; no special processing will be required. */
2654 png_color_16 c;
2655 png_uint_32 gray = back_g;
2656
2657 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2658 png_error(png_ptr, "gray-alpha color-map: too few entries");
2659
2660 cmap_entries = (unsigned int)make_gray_colormap(display);
2661
2662 if (output_encoding == P_LINEAR)
2663 {
2664 gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2665
2666 /* And make sure the corresponding palette entry matches. */
2667 png_create_colormap_entry(display, gray, back_g, back_g,
2668 back_g, 65535, P_LINEAR);
2669 }
2670
2671 /* The background passed to libpng, however, must be the sRGB
2672 * value.
2673 */
2674 c.index = 0; /*unused*/
2675 c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2676
2677 png_set_background_fixed(png_ptr, &c,
2678 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2679 0/*gamma: not used*/);
2680
2681 output_processing = PNG_CMAP_NONE;
2682 }
2683
2684 else
2685 {
2686 png_uint_32 i, a;
2687
2688 /* This is the same as png_make_ga_colormap, above, except that
2689 * the entries are all opaque.
2690 */
2691 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2692 png_error(png_ptr, "ga-alpha color-map: too few entries");
2693
2694 i = 0;
2695 while (i < 231)
2696 {
2697 png_uint_32 gray = (i * 256 + 115) / 231;
2698 png_create_colormap_entry(display, i++, gray, gray, gray,
2699 255, P_sRGB);
2700 }
2701
2702 /* NOTE: this preserves the full precision of the application
2703 * background color.
2704 */
2705 background_index = i;
2706 png_create_colormap_entry(display, i++, back_r, back_g, back_b,
2707 #ifdef __COVERITY__
2708 /* Coverity claims that output_encoding
2709 * cannot be 2 (P_LINEAR) here.
2710 */ 255U,
2711 #else
2712 output_encoding == P_LINEAR ? 65535U : 255U,
2713 #endif
2714 output_encoding);
2715
2716 /* For non-opaque input composite on the sRGB background - this
2717 * requires inverting the encoding for each component. The input
2718 * is still converted to the sRGB encoding because this is a
2719 * reasonable approximate to the logarithmic curve of human
2720 * visual sensitivity, at least over the narrow range which PNG
2721 * represents. Consequently 'G' is always sRGB encoded, while
2722 * 'A' is linear. We need the linear background colors.
2723 */
2724 if (output_encoding == P_sRGB) /* else already linear */
2725 {
2726 /* This may produce a value not exactly matching the
2727 * background, but that's ok because these numbers are only
2728 * used when alpha != 0
2729 */
2730 back_r = png_sRGB_table[back_r];
2731 back_g = png_sRGB_table[back_g];
2732 back_b = png_sRGB_table[back_b];
2733 }
2734
2735 for (a=1; a<5; ++a)
2736 {
2737 unsigned int g;
2738
2739 /* PNG_sRGB_FROM_LINEAR expects a 16-bit linear value scaled
2740 * by an 8-bit alpha value (0..255).
2741 */
2742 png_uint_32 alpha = 51 * a;
2743 png_uint_32 back_rx = (255-alpha) * back_r;
2744 png_uint_32 back_gx = (255-alpha) * back_g;
2745 png_uint_32 back_bx = (255-alpha) * back_b;
2746
2747 for (g=0; g<6; ++g)
2748 {
2749 png_uint_32 gray = png_sRGB_table[g*51] * alpha;
2750
2751 png_create_colormap_entry(display, i++,
2752 PNG_sRGB_FROM_LINEAR(gray + back_rx),
2753 PNG_sRGB_FROM_LINEAR(gray + back_gx),
2754 PNG_sRGB_FROM_LINEAR(gray + back_bx), 255, P_sRGB);
2755 }
2756 }
2757
2758 cmap_entries = i;
2759 output_processing = PNG_CMAP_GA;
2760 }
2761 }
2762 break;
2763
2764 case PNG_COLOR_TYPE_RGB:
2765 case PNG_COLOR_TYPE_RGB_ALPHA:
2766 /* Exclude the case where the output is gray; we can always handle this
2767 * with the cases above.
2768 */
2769 if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0)
2770 {
2771 /* The color-map will be grayscale, so we may as well convert the
2772 * input RGB values to a simple grayscale and use the grayscale
2773 * code above.
2774 *
2775 * NOTE: calling this apparently damages the recognition of the
2776 * transparent color in background color handling; call
2777 * png_set_tRNS_to_alpha before png_set_background_fixed.
2778 */
2779 png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, -1,
2780 -1);
2781 data_encoding = P_sRGB;
2782
2783 /* The output will now be one or two 8-bit gray or gray+alpha
2784 * channels. The more complex case arises when the input has alpha.
2785 */
2786 if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2787 png_ptr->num_trans > 0) &&
2788 (output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2789 {
2790 /* Both input and output have an alpha channel, so no background
2791 * processing is required; just map the GA bytes to the right
2792 * color-map entry.
2793 */
2794 expand_tRNS = 1;
2795
2796 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2797 png_error(png_ptr, "rgb[ga] color-map: too few entries");
2798
2799 cmap_entries = (unsigned int)make_ga_colormap(display);
2800 background_index = PNG_CMAP_GA_BACKGROUND;
2801 output_processing = PNG_CMAP_GA;
2802 }
2803
2804 else
2805 {
2806 /* Either the input or the output has no alpha channel, so there
2807 * will be no non-opaque pixels in the color-map; it will just be
2808 * grayscale.
2809 */
2810 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2811 png_error(png_ptr, "rgb[gray] color-map: too few entries");
2812
2813 /* Ideally this code would use libpng to do the gamma correction,
2814 * but if an input alpha channel is to be removed we will hit the
2815 * libpng bug in gamma+compose+rgb-to-gray (the double gamma
2816 * correction bug). Fix this by dropping the gamma correction in
2817 * this case and doing it in the palette; this will result in
2818 * duplicate palette entries, but that's better than the
2819 * alternative of double gamma correction.
2820 */
2821 if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2822 png_ptr->num_trans > 0) &&
2823 png_gamma_not_sRGB(png_ptr->colorspace.gamma) != 0)
2824 {
2825 cmap_entries = (unsigned int)make_gray_file_colormap(display);
2826 data_encoding = P_FILE;
2827 }
2828
2829 else
2830 cmap_entries = (unsigned int)make_gray_colormap(display);
2831
2832 /* But if the input has alpha or transparency it must be removed
2833 */
2834 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2835 png_ptr->num_trans > 0)
2836 {
2837 png_color_16 c;
2838 png_uint_32 gray = back_g;
2839
2840 /* We need to ensure that the application background exists in
2841 * the colormap and that completely transparent pixels map to
2842 * it. Achieve this simply by ensuring that the entry
2843 * selected for the background really is the background color.
2844 */
2845 if (data_encoding == P_FILE) /* from the fixup above */
2846 {
2847 /* The app supplied a gray which is in output_encoding, we
2848 * need to convert it to a value of the input (P_FILE)
2849 * encoding then set this palette entry to the required
2850 * output encoding.
2851 */
2852 if (output_encoding == P_sRGB)
2853 gray = png_sRGB_table[gray]; /* now P_LINEAR */
2854
2855 gray = PNG_DIV257(png_gamma_16bit_correct(gray,
2856 png_ptr->colorspace.gamma)); /* now P_FILE */
2857
2858 /* And make sure the corresponding palette entry contains
2859 * exactly the required sRGB value.
2860 */
2861 png_create_colormap_entry(display, gray, back_g, back_g,
2862 back_g, 0/*unused*/, output_encoding);
2863 }
2864
2865 else if (output_encoding == P_LINEAR)
2866 {
2867 gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2868
2869 /* And make sure the corresponding palette entry matches.
2870 */
2871 png_create_colormap_entry(display, gray, back_g, back_g,
2872 back_g, 0/*unused*/, P_LINEAR);
2873 }
2874
2875 /* The background passed to libpng, however, must be the
2876 * output (normally sRGB) value.
2877 */
2878 c.index = 0; /*unused*/
2879 c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2880
2881 /* NOTE: the following is apparently a bug in libpng. Without
2882 * it the transparent color recognition in
2883 * png_set_background_fixed seems to go wrong.
2884 */
2885 expand_tRNS = 1;
2886 png_set_background_fixed(png_ptr, &c,
2887 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2888 0/*gamma: not used*/);
2889 }
2890
2891 output_processing = PNG_CMAP_NONE;
2892 }
2893 }
2894
2895 else /* output is color */
2896 {
2897 /* We could use png_quantize here so long as there is no transparent
2898 * color or alpha; png_quantize ignores alpha. Easier overall just
2899 * to do it once and using PNG_DIV51 on the 6x6x6 reduced RGB cube.
2900 * Consequently we always want libpng to produce sRGB data.
2901 */
2902 data_encoding = P_sRGB;
2903
2904 /* Is there any transparency or alpha? */
2905 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2906 png_ptr->num_trans > 0)
2907 {
2908 /* Is there alpha in the output too? If so all four channels are
2909 * processed into a special RGB cube with alpha support.
2910 */
2911 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2912 {
2913 png_uint_32 r;
2914
2915 if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
2916 png_error(png_ptr, "rgb+alpha color-map: too few entries");
2917
2918 cmap_entries = (unsigned int)make_rgb_colormap(display);
2919
2920 /* Add a transparent entry. */
2921 png_create_colormap_entry(display, cmap_entries, 255, 255,
2922 255, 0, P_sRGB);
2923
2924 /* This is stored as the background index for the processing
2925 * algorithm.
2926 */
2927 background_index = cmap_entries++;
2928
2929 /* Add 27 r,g,b entries each with alpha 0.5. */
2930 for (r=0; r<256; r = (r << 1) | 0x7f)
2931 {
2932 png_uint_32 g;
2933
2934 for (g=0; g<256; g = (g << 1) | 0x7f)
2935 {
2936 png_uint_32 b;
2937
2938 /* This generates components with the values 0, 127 and
2939 * 255
2940 */
2941 for (b=0; b<256; b = (b << 1) | 0x7f)
2942 png_create_colormap_entry(display, cmap_entries++,
2943 r, g, b, 128, P_sRGB);
2944 }
2945 }
2946
2947 expand_tRNS = 1;
2948 output_processing = PNG_CMAP_RGB_ALPHA;
2949 }
2950
2951 else
2952 {
2953 /* Alpha/transparency must be removed. The background must
2954 * exist in the color map (achieved by setting adding it after
2955 * the 666 color-map). If the standard processing code will
2956 * pick up this entry automatically that's all that is
2957 * required; libpng can be called to do the background
2958 * processing.
2959 */
2960 unsigned int sample_size =
2961 PNG_IMAGE_SAMPLE_SIZE(output_format);
2962 png_uint_32 r, g, b; /* sRGB background */
2963
2964 if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
2965 png_error(png_ptr, "rgb-alpha color-map: too few entries");
2966
2967 cmap_entries = (unsigned int)make_rgb_colormap(display);
2968
2969 png_create_colormap_entry(display, cmap_entries, back_r,
2970 back_g, back_b, 0/*unused*/, output_encoding);
2971
2972 if (output_encoding == P_LINEAR)
2973 {
2974 r = PNG_sRGB_FROM_LINEAR(back_r * 255);
2975 g = PNG_sRGB_FROM_LINEAR(back_g * 255);
2976 b = PNG_sRGB_FROM_LINEAR(back_b * 255);
2977 }
2978
2979 else
2980 {
2981 r = back_r;
2982 g = back_g;
2983 b = back_g;
2984 }
2985
2986 /* Compare the newly-created color-map entry with the one the
2987 * PNG_CMAP_RGB algorithm will use. If the two entries don't
2988 * match, add the new one and set this as the background
2989 * index.
2990 */
2991 if (memcmp((png_const_bytep)display->colormap +
2992 sample_size * cmap_entries,
2993 (png_const_bytep)display->colormap +
2994 sample_size * PNG_RGB_INDEX(r,g,b),
2995 sample_size) != 0)
2996 {
2997 /* The background color must be added. */
2998 background_index = cmap_entries++;
2999
3000 /* Add 27 r,g,b entries each with created by composing with
3001 * the background at alpha 0.5.
3002 */
3003 for (r=0; r<256; r = (r << 1) | 0x7f)
3004 {
3005 for (g=0; g<256; g = (g << 1) | 0x7f)
3006 {
3007 /* This generates components with the values 0, 127
3008 * and 255
3009 */
3010 for (b=0; b<256; b = (b << 1) | 0x7f)
3011 png_create_colormap_entry(display, cmap_entries++,
3012 png_colormap_compose(display, r, P_sRGB, 128,
3013 back_r, output_encoding),
3014 png_colormap_compose(display, g, P_sRGB, 128,
3015 back_g, output_encoding),
3016 png_colormap_compose(display, b, P_sRGB, 128,
3017 back_b, output_encoding),
3018 0/*unused*/, output_encoding);
3019 }
3020 }
3021
3022 expand_tRNS = 1;
3023 output_processing = PNG_CMAP_RGB_ALPHA;
3024 }
3025
3026 else /* background color is in the standard color-map */
3027 {
3028 png_color_16 c;
3029
3030 c.index = 0; /*unused*/
3031 c.red = (png_uint_16)back_r;
3032 c.gray = c.green = (png_uint_16)back_g;
3033 c.blue = (png_uint_16)back_b;
3034
3035 png_set_background_fixed(png_ptr, &c,
3036 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
3037 0/*gamma: not used*/);
3038
3039 output_processing = PNG_CMAP_RGB;
3040 }
3041 }
3042 }
3043
3044 else /* no alpha or transparency in the input */
3045 {
3046 /* Alpha in the output is irrelevant, simply map the opaque input
3047 * pixels to the 6x6x6 color-map.
3048 */
3049 if (PNG_RGB_COLORMAP_ENTRIES > image->colormap_entries)
3050 png_error(png_ptr, "rgb color-map: too few entries");
3051
3052 cmap_entries = (unsigned int)make_rgb_colormap(display);
3053 output_processing = PNG_CMAP_RGB;
3054 }
3055 }
3056 break;
3057
3058 case PNG_COLOR_TYPE_PALETTE:
3059 /* It's already got a color-map. It may be necessary to eliminate the
3060 * tRNS entries though.
3061 */
3062 {
3063 unsigned int num_trans = png_ptr->num_trans;
3064 png_const_bytep trans = num_trans > 0 ? png_ptr->trans_alpha : NULL;
3065 png_const_colorp colormap = png_ptr->palette;
3066 int do_background = trans != NULL &&
3067 (output_format & PNG_FORMAT_FLAG_ALPHA) == 0;
3068 unsigned int i;
3069
3070 /* Just in case: */
3071 if (trans == NULL)
3072 num_trans = 0;
3073
3074 output_processing = PNG_CMAP_NONE;
3075 data_encoding = P_FILE; /* Don't change from color-map indices */
3076 cmap_entries = (unsigned int)png_ptr->num_palette;
3077 if (cmap_entries > 256)
3078 cmap_entries = 256;
3079
3080 if (cmap_entries > (unsigned int)image->colormap_entries)
3081 png_error(png_ptr, "palette color-map: too few entries");
3082
3083 for (i=0; i < cmap_entries; ++i)
3084 {
3085 if (do_background != 0 && i < num_trans && trans[i] < 255)
3086 {
3087 if (trans[i] == 0)
3088 png_create_colormap_entry(display, i, back_r, back_g,
3089 back_b, 0, output_encoding);
3090
3091 else
3092 {
3093 /* Must compose the PNG file color in the color-map entry
3094 * on the sRGB color in 'back'.
3095 */
3096 png_create_colormap_entry(display, i,
3097 png_colormap_compose(display, colormap[i].red,
3098 P_FILE, trans[i], back_r, output_encoding),
3099 png_colormap_compose(display, colormap[i].green,
3100 P_FILE, trans[i], back_g, output_encoding),
3101 png_colormap_compose(display, colormap[i].blue,
3102 P_FILE, trans[i], back_b, output_encoding),
3103 output_encoding == P_LINEAR ? trans[i] * 257U :
3104 trans[i],
3105 output_encoding);
3106 }
3107 }
3108
3109 else
3110 png_create_colormap_entry(display, i, colormap[i].red,
3111 colormap[i].green, colormap[i].blue,
3112 i < num_trans ? trans[i] : 255U, P_FILE/*8-bit*/);
3113 }
3114
3115 /* The PNG data may have indices packed in fewer than 8 bits, it
3116 * must be expanded if so.
3117 */
3118 if (png_ptr->bit_depth < 8)
3119 png_set_packing(png_ptr);
3120 }
3121 break;
3122
3123 default:
3124 png_error(png_ptr, "invalid PNG color type");
3125 /*NOT REACHED*/
3126 }
3127
3128 /* Now deal with the output processing */
3129 if (expand_tRNS != 0 && png_ptr->num_trans > 0 &&
3130 (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0)
3131 png_set_tRNS_to_alpha(png_ptr);
3132
3133 switch (data_encoding)
3134 {
3135 case P_sRGB:
3136 /* Change to 8-bit sRGB */
3137 png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB);
3138 /* FALLTHROUGH */
3139
3140 case P_FILE:
3141 if (png_ptr->bit_depth > 8)
3142 png_set_scale_16(png_ptr);
3143 break;
3144
3145 #ifdef __GNUC__
3146 default:
3147 png_error(png_ptr, "bad data option (internal error)");
3148 #endif
3149 }
3150
3151 if (cmap_entries > 256 || cmap_entries > image->colormap_entries)
3152 png_error(png_ptr, "color map overflow (BAD internal error)");
3153
3154 image->colormap_entries = cmap_entries;
3155
3156 /* Double check using the recorded background index */
3157 switch (output_processing)
3158 {
3159 case PNG_CMAP_NONE:
3160 if (background_index != PNG_CMAP_NONE_BACKGROUND)
3161 goto bad_background;
3162 break;
3163
3164 case PNG_CMAP_GA:
3165 if (background_index != PNG_CMAP_GA_BACKGROUND)
3166 goto bad_background;
3167 break;
3168
3169 case PNG_CMAP_TRANS:
3170 if (background_index >= cmap_entries ||
3171 background_index != PNG_CMAP_TRANS_BACKGROUND)
3172 goto bad_background;
3173 break;
3174
3175 case PNG_CMAP_RGB:
3176 if (background_index != PNG_CMAP_RGB_BACKGROUND)
3177 goto bad_background;
3178 break;
3179
3180 case PNG_CMAP_RGB_ALPHA:
3181 if (background_index != PNG_CMAP_RGB_ALPHA_BACKGROUND)
3182 goto bad_background;
3183 break;
3184
3185 default:
3186 png_error(png_ptr, "bad processing option (internal error)");
3187
3188 bad_background:
3189 png_error(png_ptr, "bad background index (internal error)");
3190 }
3191
3192 display->colormap_processing = (int)output_processing;
3193
3194 return 1/*ok*/;
3195 }
3196
3197 /* The final part of the color-map read called from png_image_finish_read. */
3198 static int
png_image_read_and_map(png_voidp argument)3199 png_image_read_and_map(png_voidp argument)
3200 {
3201 png_image_read_control *display = png_voidcast(png_image_read_control*,
3202 argument);
3203 png_imagep image = display->image;
3204 png_structrp png_ptr = image->opaque->png_ptr;
3205 int passes;
3206
3207 /* Called when the libpng data must be transformed into the color-mapped
3208 * form. There is a local row buffer in display->local and this routine must
3209 * do the interlace handling.
3210 */
3211 switch (png_ptr->interlaced)
3212 {
3213 case PNG_INTERLACE_NONE:
3214 passes = 1;
3215 break;
3216
3217 case PNG_INTERLACE_ADAM7:
3218 passes = PNG_INTERLACE_ADAM7_PASSES;
3219 break;
3220
3221 default:
3222 png_error(png_ptr, "unknown interlace type");
3223 }
3224
3225 {
3226 png_uint_32 height = image->height;
3227 png_uint_32 width = image->width;
3228 int proc = display->colormap_processing;
3229 png_bytep first_row = png_voidcast(png_bytep, display->first_row);
3230 ptrdiff_t step_row = display->row_bytes;
3231 int pass;
3232
3233 for (pass = 0; pass < passes; ++pass)
3234 {
3235 unsigned int startx, stepx, stepy;
3236 png_uint_32 y;
3237
3238 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3239 {
3240 /* The row may be empty for a short image: */
3241 if (PNG_PASS_COLS(width, pass) == 0)
3242 continue;
3243
3244 startx = PNG_PASS_START_COL(pass);
3245 stepx = PNG_PASS_COL_OFFSET(pass);
3246 y = PNG_PASS_START_ROW(pass);
3247 stepy = PNG_PASS_ROW_OFFSET(pass);
3248 }
3249
3250 else
3251 {
3252 y = 0;
3253 startx = 0;
3254 stepx = stepy = 1;
3255 }
3256
3257 for (; y<height; y += stepy)
3258 {
3259 png_bytep inrow = png_voidcast(png_bytep, display->local_row);
3260 png_bytep outrow = first_row + y * step_row;
3261 png_const_bytep end_row = outrow + width;
3262
3263 /* Read read the libpng data into the temporary buffer. */
3264 png_read_row(png_ptr, inrow, NULL);
3265
3266 /* Now process the row according to the processing option, note
3267 * that the caller verifies that the format of the libpng output
3268 * data is as required.
3269 */
3270 outrow += startx;
3271 switch (proc)
3272 {
3273 case PNG_CMAP_GA:
3274 for (; outrow < end_row; outrow += stepx)
3275 {
3276 /* The data is always in the PNG order */
3277 unsigned int gray = *inrow++;
3278 unsigned int alpha = *inrow++;
3279 unsigned int entry;
3280
3281 /* NOTE: this code is copied as a comment in
3282 * make_ga_colormap above. Please update the
3283 * comment if you change this code!
3284 */
3285 if (alpha > 229) /* opaque */
3286 {
3287 entry = (231 * gray + 128) >> 8;
3288 }
3289 else if (alpha < 26) /* transparent */
3290 {
3291 entry = 231;
3292 }
3293 else /* partially opaque */
3294 {
3295 entry = 226 + 6 * PNG_DIV51(alpha) + PNG_DIV51(gray);
3296 }
3297
3298 *outrow = (png_byte)entry;
3299 }
3300 break;
3301
3302 case PNG_CMAP_TRANS:
3303 for (; outrow < end_row; outrow += stepx)
3304 {
3305 png_byte gray = *inrow++;
3306 png_byte alpha = *inrow++;
3307
3308 if (alpha == 0)
3309 *outrow = PNG_CMAP_TRANS_BACKGROUND;
3310
3311 else if (gray != PNG_CMAP_TRANS_BACKGROUND)
3312 *outrow = gray;
3313
3314 else
3315 *outrow = (png_byte)(PNG_CMAP_TRANS_BACKGROUND+1);
3316 }
3317 break;
3318
3319 case PNG_CMAP_RGB:
3320 for (; outrow < end_row; outrow += stepx)
3321 {
3322 *outrow = PNG_RGB_INDEX(inrow[0], inrow[1], inrow[2]);
3323 inrow += 3;
3324 }
3325 break;
3326
3327 case PNG_CMAP_RGB_ALPHA:
3328 for (; outrow < end_row; outrow += stepx)
3329 {
3330 unsigned int alpha = inrow[3];
3331
3332 /* Because the alpha entries only hold alpha==0.5 values
3333 * split the processing at alpha==0.25 (64) and 0.75
3334 * (196).
3335 */
3336
3337 if (alpha >= 196)
3338 *outrow = PNG_RGB_INDEX(inrow[0], inrow[1],
3339 inrow[2]);
3340
3341 else if (alpha < 64)
3342 *outrow = PNG_CMAP_RGB_ALPHA_BACKGROUND;
3343
3344 else
3345 {
3346 /* Likewise there are three entries for each of r, g
3347 * and b. We could select the entry by popcount on
3348 * the top two bits on those architectures that
3349 * support it, this is what the code below does,
3350 * crudely.
3351 */
3352 unsigned int back_i = PNG_CMAP_RGB_ALPHA_BACKGROUND+1;
3353
3354 /* Here are how the values map:
3355 *
3356 * 0x00 .. 0x3f -> 0
3357 * 0x40 .. 0xbf -> 1
3358 * 0xc0 .. 0xff -> 2
3359 *
3360 * So, as above with the explicit alpha checks, the
3361 * breakpoints are at 64 and 196.
3362 */
3363 if (inrow[0] & 0x80) back_i += 9; /* red */
3364 if (inrow[0] & 0x40) back_i += 9;
3365 if (inrow[0] & 0x80) back_i += 3; /* green */
3366 if (inrow[0] & 0x40) back_i += 3;
3367 if (inrow[0] & 0x80) back_i += 1; /* blue */
3368 if (inrow[0] & 0x40) back_i += 1;
3369
3370 *outrow = (png_byte)back_i;
3371 }
3372
3373 inrow += 4;
3374 }
3375 break;
3376
3377 default:
3378 break;
3379 }
3380 }
3381 }
3382 }
3383
3384 return 1;
3385 }
3386
3387 static int
png_image_read_colormapped(png_voidp argument)3388 png_image_read_colormapped(png_voidp argument)
3389 {
3390 png_image_read_control *display = png_voidcast(png_image_read_control*,
3391 argument);
3392 png_imagep image = display->image;
3393 png_controlp control = image->opaque;
3394 png_structrp png_ptr = control->png_ptr;
3395 png_inforp info_ptr = control->info_ptr;
3396
3397 int passes = 0; /* As a flag */
3398
3399 PNG_SKIP_CHUNKS(png_ptr);
3400
3401 /* Update the 'info' structure and make sure the result is as required; first
3402 * make sure to turn on the interlace handling if it will be required
3403 * (because it can't be turned on *after* the call to png_read_update_info!)
3404 */
3405 if (display->colormap_processing == PNG_CMAP_NONE)
3406 passes = png_set_interlace_handling(png_ptr);
3407
3408 png_read_update_info(png_ptr, info_ptr);
3409
3410 /* The expected output can be deduced from the colormap_processing option. */
3411 switch (display->colormap_processing)
3412 {
3413 case PNG_CMAP_NONE:
3414 /* Output must be one channel and one byte per pixel, the output
3415 * encoding can be anything.
3416 */
3417 if ((info_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
3418 info_ptr->color_type == PNG_COLOR_TYPE_GRAY) &&
3419 info_ptr->bit_depth == 8)
3420 break;
3421
3422 goto bad_output;
3423
3424 case PNG_CMAP_TRANS:
3425 case PNG_CMAP_GA:
3426 /* Output must be two channels and the 'G' one must be sRGB, the latter
3427 * can be checked with an exact number because it should have been set
3428 * to this number above!
3429 */
3430 if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA &&
3431 info_ptr->bit_depth == 8 &&
3432 png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3433 image->colormap_entries == 256)
3434 break;
3435
3436 goto bad_output;
3437
3438 case PNG_CMAP_RGB:
3439 /* Output must be 8-bit sRGB encoded RGB */
3440 if (info_ptr->color_type == PNG_COLOR_TYPE_RGB &&
3441 info_ptr->bit_depth == 8 &&
3442 png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3443 image->colormap_entries == 216)
3444 break;
3445
3446 goto bad_output;
3447
3448 case PNG_CMAP_RGB_ALPHA:
3449 /* Output must be 8-bit sRGB encoded RGBA */
3450 if (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
3451 info_ptr->bit_depth == 8 &&
3452 png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3453 image->colormap_entries == 244 /* 216 + 1 + 27 */)
3454 break;
3455
3456 goto bad_output;
3457
3458 default:
3459 bad_output:
3460 png_error(png_ptr, "bad color-map processing (internal error)");
3461 }
3462
3463 /* Now read the rows. Do this here if it is possible to read directly into
3464 * the output buffer, otherwise allocate a local row buffer of the maximum
3465 * size libpng requires and call the relevant processing routine safely.
3466 */
3467 {
3468 png_voidp first_row = display->buffer;
3469 ptrdiff_t row_bytes = display->row_stride;
3470
3471 /* The following expression is designed to work correctly whether it gives
3472 * a signed or an unsigned result.
3473 */
3474 if (row_bytes < 0)
3475 {
3476 char *ptr = png_voidcast(char*, first_row);
3477 ptr += (image->height-1) * (-row_bytes);
3478 first_row = png_voidcast(png_voidp, ptr);
3479 }
3480
3481 display->first_row = first_row;
3482 display->row_bytes = row_bytes;
3483 }
3484
3485 if (passes == 0)
3486 {
3487 int result;
3488 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
3489
3490 display->local_row = row;
3491 result = png_safe_execute(image, png_image_read_and_map, display);
3492 display->local_row = NULL;
3493 png_free(png_ptr, row);
3494
3495 return result;
3496 }
3497
3498 else
3499 {
3500 png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes;
3501
3502 while (--passes >= 0)
3503 {
3504 png_uint_32 y = image->height;
3505 png_bytep row = png_voidcast(png_bytep, display->first_row);
3506
3507 for (; y > 0; --y)
3508 {
3509 png_read_row(png_ptr, row, NULL);
3510 row += row_bytes;
3511 }
3512 }
3513
3514 return 1;
3515 }
3516 }
3517
3518 /* Just the row reading part of png_image_read. */
3519 static int
png_image_read_composite(png_voidp argument)3520 png_image_read_composite(png_voidp argument)
3521 {
3522 png_image_read_control *display = png_voidcast(png_image_read_control*,
3523 argument);
3524 png_imagep image = display->image;
3525 png_structrp png_ptr = image->opaque->png_ptr;
3526 int passes;
3527
3528 switch (png_ptr->interlaced)
3529 {
3530 case PNG_INTERLACE_NONE:
3531 passes = 1;
3532 break;
3533
3534 case PNG_INTERLACE_ADAM7:
3535 passes = PNG_INTERLACE_ADAM7_PASSES;
3536 break;
3537
3538 default:
3539 png_error(png_ptr, "unknown interlace type");
3540 }
3541
3542 {
3543 png_uint_32 height = image->height;
3544 png_uint_32 width = image->width;
3545 ptrdiff_t step_row = display->row_bytes;
3546 unsigned int channels =
3547 (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
3548 int pass;
3549
3550 for (pass = 0; pass < passes; ++pass)
3551 {
3552 unsigned int startx, stepx, stepy;
3553 png_uint_32 y;
3554
3555 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3556 {
3557 /* The row may be empty for a short image: */
3558 if (PNG_PASS_COLS(width, pass) == 0)
3559 continue;
3560
3561 startx = PNG_PASS_START_COL(pass) * channels;
3562 stepx = PNG_PASS_COL_OFFSET(pass) * channels;
3563 y = PNG_PASS_START_ROW(pass);
3564 stepy = PNG_PASS_ROW_OFFSET(pass);
3565 }
3566
3567 else
3568 {
3569 y = 0;
3570 startx = 0;
3571 stepx = channels;
3572 stepy = 1;
3573 }
3574
3575 for (; y<height; y += stepy)
3576 {
3577 png_bytep inrow = png_voidcast(png_bytep, display->local_row);
3578 png_bytep outrow;
3579 png_const_bytep end_row;
3580
3581 /* Read the row, which is packed: */
3582 png_read_row(png_ptr, inrow, NULL);
3583
3584 outrow = png_voidcast(png_bytep, display->first_row);
3585 outrow += y * step_row;
3586 end_row = outrow + width * channels;
3587
3588 /* Now do the composition on each pixel in this row. */
3589 outrow += startx;
3590 for (; outrow < end_row; outrow += stepx)
3591 {
3592 png_byte alpha = inrow[channels];
3593
3594 if (alpha > 0) /* else no change to the output */
3595 {
3596 unsigned int c;
3597
3598 for (c=0; c<channels; ++c)
3599 {
3600 png_uint_32 component = inrow[c];
3601
3602 if (alpha < 255) /* else just use component */
3603 {
3604 /* This is PNG_OPTIMIZED_ALPHA, the component value
3605 * is a linear 8-bit value. Combine this with the
3606 * current outrow[c] value which is sRGB encoded.
3607 * Arithmetic here is 16-bits to preserve the output
3608 * values correctly.
3609 */
3610 component *= 257*255; /* =65535 */
3611 component += (255-alpha)*png_sRGB_table[outrow[c]];
3612
3613 /* So 'component' is scaled by 255*65535 and is
3614 * therefore appropriate for the sRGB to linear
3615 * conversion table.
3616 */
3617 component = PNG_sRGB_FROM_LINEAR(component);
3618 }
3619
3620 outrow[c] = (png_byte)component;
3621 }
3622 }
3623
3624 inrow += channels+1; /* components and alpha channel */
3625 }
3626 }
3627 }
3628 }
3629
3630 return 1;
3631 }
3632
3633 /* The do_local_background case; called when all the following transforms are to
3634 * be done:
3635 *
3636 * PNG_RGB_TO_GRAY
3637 * PNG_COMPOSITE
3638 * PNG_GAMMA
3639 *
3640 * This is a work-around for the fact that both the PNG_RGB_TO_GRAY and
3641 * PNG_COMPOSITE code performs gamma correction, so we get double gamma
3642 * correction. The fix-up is to prevent the PNG_COMPOSITE operation from
3643 * happening inside libpng, so this routine sees an 8 or 16-bit gray+alpha
3644 * row and handles the removal or pre-multiplication of the alpha channel.
3645 */
3646 static int
png_image_read_background(png_voidp argument)3647 png_image_read_background(png_voidp argument)
3648 {
3649 png_image_read_control *display = png_voidcast(png_image_read_control*,
3650 argument);
3651 png_imagep image = display->image;
3652 png_structrp png_ptr = image->opaque->png_ptr;
3653 png_inforp info_ptr = image->opaque->info_ptr;
3654 png_uint_32 height = image->height;
3655 png_uint_32 width = image->width;
3656 int pass, passes;
3657
3658 /* Double check the convoluted logic below. We expect to get here with
3659 * libpng doing rgb to gray and gamma correction but background processing
3660 * left to the png_image_read_background function. The rows libpng produce
3661 * might be 8 or 16-bit but should always have two channels; gray plus alpha.
3662 */
3663 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
3664 png_error(png_ptr, "lost rgb to gray");
3665
3666 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
3667 png_error(png_ptr, "unexpected compose");
3668
3669 if (png_get_channels(png_ptr, info_ptr) != 2)
3670 png_error(png_ptr, "lost/gained channels");
3671
3672 /* Expect the 8-bit case to always remove the alpha channel */
3673 if ((image->format & PNG_FORMAT_FLAG_LINEAR) == 0 &&
3674 (image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
3675 png_error(png_ptr, "unexpected 8-bit transformation");
3676
3677 switch (png_ptr->interlaced)
3678 {
3679 case PNG_INTERLACE_NONE:
3680 passes = 1;
3681 break;
3682
3683 case PNG_INTERLACE_ADAM7:
3684 passes = PNG_INTERLACE_ADAM7_PASSES;
3685 break;
3686
3687 default:
3688 png_error(png_ptr, "unknown interlace type");
3689 }
3690
3691 /* Use direct access to info_ptr here because otherwise the simplified API
3692 * would require PNG_EASY_ACCESS_SUPPORTED (just for this.) Note this is
3693 * checking the value after libpng expansions, not the original value in the
3694 * PNG.
3695 */
3696 switch (info_ptr->bit_depth)
3697 {
3698 case 8:
3699 /* 8-bit sRGB gray values with an alpha channel; the alpha channel is
3700 * to be removed by composing on a background: either the row if
3701 * display->background is NULL or display->background->green if not.
3702 * Unlike the code above ALPHA_OPTIMIZED has *not* been done.
3703 */
3704 {
3705 png_bytep first_row = png_voidcast(png_bytep, display->first_row);
3706 ptrdiff_t step_row = display->row_bytes;
3707
3708 for (pass = 0; pass < passes; ++pass)
3709 {
3710 png_bytep row = png_voidcast(png_bytep, display->first_row);
3711 unsigned int startx, stepx, stepy;
3712 png_uint_32 y;
3713
3714 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3715 {
3716 /* The row may be empty for a short image: */
3717 if (PNG_PASS_COLS(width, pass) == 0)
3718 continue;
3719
3720 startx = PNG_PASS_START_COL(pass);
3721 stepx = PNG_PASS_COL_OFFSET(pass);
3722 y = PNG_PASS_START_ROW(pass);
3723 stepy = PNG_PASS_ROW_OFFSET(pass);
3724 }
3725
3726 else
3727 {
3728 y = 0;
3729 startx = 0;
3730 stepx = stepy = 1;
3731 }
3732
3733 if (display->background == NULL)
3734 {
3735 for (; y<height; y += stepy)
3736 {
3737 png_bytep inrow = png_voidcast(png_bytep,
3738 display->local_row);
3739 png_bytep outrow = first_row + y * step_row;
3740 png_const_bytep end_row = outrow + width;
3741
3742 /* Read the row, which is packed: */
3743 png_read_row(png_ptr, inrow, NULL);
3744
3745 /* Now do the composition on each pixel in this row. */
3746 outrow += startx;
3747 for (; outrow < end_row; outrow += stepx)
3748 {
3749 png_byte alpha = inrow[1];
3750
3751 if (alpha > 0) /* else no change to the output */
3752 {
3753 png_uint_32 component = inrow[0];
3754
3755 if (alpha < 255) /* else just use component */
3756 {
3757 /* Since PNG_OPTIMIZED_ALPHA was not set it is
3758 * necessary to invert the sRGB transfer
3759 * function and multiply the alpha out.
3760 */
3761 component = png_sRGB_table[component] * alpha;
3762 component += png_sRGB_table[outrow[0]] *
3763 (255-alpha);
3764 component = PNG_sRGB_FROM_LINEAR(component);
3765 }
3766
3767 outrow[0] = (png_byte)component;
3768 }
3769
3770 inrow += 2; /* gray and alpha channel */
3771 }
3772 }
3773 }
3774
3775 else /* constant background value */
3776 {
3777 png_byte background8 = display->background->green;
3778 png_uint_16 background = png_sRGB_table[background8];
3779
3780 for (; y<height; y += stepy)
3781 {
3782 png_bytep inrow = png_voidcast(png_bytep,
3783 display->local_row);
3784 png_bytep outrow = first_row + y * step_row;
3785 png_const_bytep end_row = outrow + width;
3786
3787 /* Read the row, which is packed: */
3788 png_read_row(png_ptr, inrow, NULL);
3789
3790 /* Now do the composition on each pixel in this row. */
3791 outrow += startx;
3792 for (; outrow < end_row; outrow += stepx)
3793 {
3794 png_byte alpha = inrow[1];
3795
3796 if (alpha > 0) /* else use background */
3797 {
3798 png_uint_32 component = inrow[0];
3799
3800 if (alpha < 255) /* else just use component */
3801 {
3802 component = png_sRGB_table[component] * alpha;
3803 component += background * (255-alpha);
3804 component = PNG_sRGB_FROM_LINEAR(component);
3805 }
3806
3807 outrow[0] = (png_byte)component;
3808 }
3809
3810 else
3811 outrow[0] = background8;
3812
3813 inrow += 2; /* gray and alpha channel */
3814 }
3815
3816 row += display->row_bytes;
3817 }
3818 }
3819 }
3820 }
3821 break;
3822
3823 case 16:
3824 /* 16-bit linear with pre-multiplied alpha; the pre-multiplication must
3825 * still be done and, maybe, the alpha channel removed. This code also
3826 * handles the alpha-first option.
3827 */
3828 {
3829 png_uint_16p first_row = png_voidcast(png_uint_16p,
3830 display->first_row);
3831 /* The division by two is safe because the caller passed in a
3832 * stride which was multiplied by 2 (below) to get row_bytes.
3833 */
3834 ptrdiff_t step_row = display->row_bytes / 2;
3835 unsigned int preserve_alpha = (image->format &
3836 PNG_FORMAT_FLAG_ALPHA) != 0;
3837 unsigned int outchannels = 1U+preserve_alpha;
3838 int swap_alpha = 0;
3839
3840 # ifdef PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED
3841 if (preserve_alpha != 0 &&
3842 (image->format & PNG_FORMAT_FLAG_AFIRST) != 0)
3843 swap_alpha = 1;
3844 # endif
3845
3846 for (pass = 0; pass < passes; ++pass)
3847 {
3848 unsigned int startx, stepx, stepy;
3849 png_uint_32 y;
3850
3851 /* The 'x' start and step are adjusted to output components here.
3852 */
3853 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3854 {
3855 /* The row may be empty for a short image: */
3856 if (PNG_PASS_COLS(width, pass) == 0)
3857 continue;
3858
3859 startx = PNG_PASS_START_COL(pass) * outchannels;
3860 stepx = PNG_PASS_COL_OFFSET(pass) * outchannels;
3861 y = PNG_PASS_START_ROW(pass);
3862 stepy = PNG_PASS_ROW_OFFSET(pass);
3863 }
3864
3865 else
3866 {
3867 y = 0;
3868 startx = 0;
3869 stepx = outchannels;
3870 stepy = 1;
3871 }
3872
3873 for (; y<height; y += stepy)
3874 {
3875 png_const_uint_16p inrow;
3876 png_uint_16p outrow = first_row + y*step_row;
3877 png_uint_16p end_row = outrow + width * outchannels;
3878
3879 /* Read the row, which is packed: */
3880 png_read_row(png_ptr, png_voidcast(png_bytep,
3881 display->local_row), NULL);
3882 inrow = png_voidcast(png_const_uint_16p, display->local_row);
3883
3884 /* Now do the pre-multiplication on each pixel in this row.
3885 */
3886 outrow += startx;
3887 for (; outrow < end_row; outrow += stepx)
3888 {
3889 png_uint_32 component = inrow[0];
3890 png_uint_16 alpha = inrow[1];
3891
3892 if (alpha > 0) /* else 0 */
3893 {
3894 if (alpha < 65535) /* else just use component */
3895 {
3896 component *= alpha;
3897 component += 32767;
3898 component /= 65535;
3899 }
3900 }
3901
3902 else
3903 component = 0;
3904
3905 outrow[swap_alpha] = (png_uint_16)component;
3906 if (preserve_alpha != 0)
3907 outrow[1 ^ swap_alpha] = alpha;
3908
3909 inrow += 2; /* components and alpha channel */
3910 }
3911 }
3912 }
3913 }
3914 break;
3915
3916 #ifdef __GNUC__
3917 default:
3918 png_error(png_ptr, "unexpected bit depth");
3919 #endif
3920 }
3921
3922 return 1;
3923 }
3924
3925 /* The guts of png_image_finish_read as a png_safe_execute callback. */
3926 static int
png_image_read_direct(png_voidp argument)3927 png_image_read_direct(png_voidp argument)
3928 {
3929 png_image_read_control *display = png_voidcast(png_image_read_control*,
3930 argument);
3931 png_imagep image = display->image;
3932 png_structrp png_ptr = image->opaque->png_ptr;
3933 png_inforp info_ptr = image->opaque->info_ptr;
3934
3935 png_uint_32 format = image->format;
3936 int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0;
3937 int do_local_compose = 0;
3938 int do_local_background = 0; /* to avoid double gamma correction bug */
3939 int passes = 0;
3940
3941 /* Add transforms to ensure the correct output format is produced then check
3942 * that the required implementation support is there. Always expand; always
3943 * need 8 bits minimum, no palette and expanded tRNS.
3944 */
3945 png_set_expand(png_ptr);
3946
3947 /* Now check the format to see if it was modified. */
3948 {
3949 png_uint_32 base_format = png_image_format(png_ptr) &
3950 ~PNG_FORMAT_FLAG_COLORMAP /* removed by png_set_expand */;
3951 png_uint_32 change = format ^ base_format;
3952 png_fixed_point output_gamma;
3953 int mode; /* alpha mode */
3954
3955 /* Do this first so that we have a record if rgb to gray is happening. */
3956 if ((change & PNG_FORMAT_FLAG_COLOR) != 0)
3957 {
3958 /* gray<->color transformation required. */
3959 if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
3960 png_set_gray_to_rgb(png_ptr);
3961
3962 else
3963 {
3964 /* libpng can't do both rgb to gray and
3965 * background/pre-multiplication if there is also significant gamma
3966 * correction, because both operations require linear colors and
3967 * the code only supports one transform doing the gamma correction.
3968 * Handle this by doing the pre-multiplication or background
3969 * operation in this code, if necessary.
3970 *
3971 * TODO: fix this by rewriting pngrtran.c (!)
3972 *
3973 * For the moment (given that fixing this in pngrtran.c is an
3974 * enormous change) 'do_local_background' is used to indicate that
3975 * the problem exists.
3976 */
3977 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3978 do_local_background = 1/*maybe*/;
3979
3980 png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE,
3981 PNG_RGB_TO_GRAY_DEFAULT, PNG_RGB_TO_GRAY_DEFAULT);
3982 }
3983
3984 change &= ~PNG_FORMAT_FLAG_COLOR;
3985 }
3986
3987 /* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise.
3988 */
3989 {
3990 png_fixed_point input_gamma_default;
3991
3992 if ((base_format & PNG_FORMAT_FLAG_LINEAR) != 0 &&
3993 (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
3994 input_gamma_default = PNG_GAMMA_LINEAR;
3995 else
3996 input_gamma_default = PNG_DEFAULT_sRGB;
3997
3998 /* Call png_set_alpha_mode to set the default for the input gamma; the
3999 * output gamma is set by a second call below.
4000 */
4001 png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, input_gamma_default);
4002 }
4003
4004 if (linear != 0)
4005 {
4006 /* If there *is* an alpha channel in the input it must be multiplied
4007 * out; use PNG_ALPHA_STANDARD, otherwise just use PNG_ALPHA_PNG.
4008 */
4009 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
4010 mode = PNG_ALPHA_STANDARD; /* associated alpha */
4011
4012 else
4013 mode = PNG_ALPHA_PNG;
4014
4015 output_gamma = PNG_GAMMA_LINEAR;
4016 }
4017
4018 else
4019 {
4020 mode = PNG_ALPHA_PNG;
4021 output_gamma = PNG_DEFAULT_sRGB;
4022 }
4023
4024 if ((change & PNG_FORMAT_FLAG_ASSOCIATED_ALPHA) != 0)
4025 {
4026 mode = PNG_ALPHA_OPTIMIZED;
4027 change &= ~PNG_FORMAT_FLAG_ASSOCIATED_ALPHA;
4028 }
4029
4030 /* If 'do_local_background' is set check for the presence of gamma
4031 * correction; this is part of the work-round for the libpng bug
4032 * described above.
4033 *
4034 * TODO: fix libpng and remove this.
4035 */
4036 if (do_local_background != 0)
4037 {
4038 png_fixed_point gtest;
4039
4040 /* This is 'png_gamma_threshold' from pngrtran.c; the test used for
4041 * gamma correction, the screen gamma hasn't been set on png_struct
4042 * yet; it's set below. png_struct::gamma, however, is set to the
4043 * final value.
4044 */
4045 if (png_muldiv(>est, output_gamma, png_ptr->colorspace.gamma,
4046 PNG_FP_1) != 0 && png_gamma_significant(gtest) == 0)
4047 do_local_background = 0;
4048
4049 else if (mode == PNG_ALPHA_STANDARD)
4050 {
4051 do_local_background = 2/*required*/;
4052 mode = PNG_ALPHA_PNG; /* prevent libpng doing it */
4053 }
4054
4055 /* else leave as 1 for the checks below */
4056 }
4057
4058 /* If the bit-depth changes then handle that here. */
4059 if ((change & PNG_FORMAT_FLAG_LINEAR) != 0)
4060 {
4061 if (linear != 0 /*16-bit output*/)
4062 png_set_expand_16(png_ptr);
4063
4064 else /* 8-bit output */
4065 png_set_scale_16(png_ptr);
4066
4067 change &= ~PNG_FORMAT_FLAG_LINEAR;
4068 }
4069
4070 /* Now the background/alpha channel changes. */
4071 if ((change & PNG_FORMAT_FLAG_ALPHA) != 0)
4072 {
4073 /* Removing an alpha channel requires composition for the 8-bit
4074 * formats; for the 16-bit it is already done, above, by the
4075 * pre-multiplication and the channel just needs to be stripped.
4076 */
4077 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
4078 {
4079 /* If RGB->gray is happening the alpha channel must be left and the
4080 * operation completed locally.
4081 *
4082 * TODO: fix libpng and remove this.
4083 */
4084 if (do_local_background != 0)
4085 do_local_background = 2/*required*/;
4086
4087 /* 16-bit output: just remove the channel */
4088 else if (linear != 0) /* compose on black (well, pre-multiply) */
4089 png_set_strip_alpha(png_ptr);
4090
4091 /* 8-bit output: do an appropriate compose */
4092 else if (display->background != NULL)
4093 {
4094 png_color_16 c;
4095
4096 c.index = 0; /*unused*/
4097 c.red = display->background->red;
4098 c.green = display->background->green;
4099 c.blue = display->background->blue;
4100 c.gray = display->background->green;
4101
4102 /* This is always an 8-bit sRGB value, using the 'green' channel
4103 * for gray is much better than calculating the luminance here;
4104 * we can get off-by-one errors in that calculation relative to
4105 * the app expectations and that will show up in transparent
4106 * pixels.
4107 */
4108 png_set_background_fixed(png_ptr, &c,
4109 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
4110 0/*gamma: not used*/);
4111 }
4112
4113 else /* compose on row: implemented below. */
4114 {
4115 do_local_compose = 1;
4116 /* This leaves the alpha channel in the output, so it has to be
4117 * removed by the code below. Set the encoding to the 'OPTIMIZE'
4118 * one so the code only has to hack on the pixels that require
4119 * composition.
4120 */
4121 mode = PNG_ALPHA_OPTIMIZED;
4122 }
4123 }
4124
4125 else /* output needs an alpha channel */
4126 {
4127 /* This is tricky because it happens before the swap operation has
4128 * been accomplished; however, the swap does *not* swap the added
4129 * alpha channel (weird API), so it must be added in the correct
4130 * place.
4131 */
4132 png_uint_32 filler; /* opaque filler */
4133 int where;
4134
4135 if (linear != 0)
4136 filler = 65535;
4137
4138 else
4139 filler = 255;
4140
4141 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
4142 if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
4143 {
4144 where = PNG_FILLER_BEFORE;
4145 change &= ~PNG_FORMAT_FLAG_AFIRST;
4146 }
4147
4148 else
4149 #endif
4150 where = PNG_FILLER_AFTER;
4151
4152 png_set_add_alpha(png_ptr, filler, where);
4153 }
4154
4155 /* This stops the (irrelevant) call to swap_alpha below. */
4156 change &= ~PNG_FORMAT_FLAG_ALPHA;
4157 }
4158
4159 /* Now set the alpha mode correctly; this is always done, even if there is
4160 * no alpha channel in either the input or the output because it correctly
4161 * sets the output gamma.
4162 */
4163 png_set_alpha_mode_fixed(png_ptr, mode, output_gamma);
4164
4165 # ifdef PNG_FORMAT_BGR_SUPPORTED
4166 if ((change & PNG_FORMAT_FLAG_BGR) != 0)
4167 {
4168 /* Check only the output format; PNG is never BGR; don't do this if
4169 * the output is gray, but fix up the 'format' value in that case.
4170 */
4171 if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
4172 png_set_bgr(png_ptr);
4173
4174 else
4175 format &= ~PNG_FORMAT_FLAG_BGR;
4176
4177 change &= ~PNG_FORMAT_FLAG_BGR;
4178 }
4179 # endif
4180
4181 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
4182 if ((change & PNG_FORMAT_FLAG_AFIRST) != 0)
4183 {
4184 /* Only relevant if there is an alpha channel - it's particularly
4185 * important to handle this correctly because do_local_compose may
4186 * be set above and then libpng will keep the alpha channel for this
4187 * code to remove.
4188 */
4189 if ((format & PNG_FORMAT_FLAG_ALPHA) != 0)
4190 {
4191 /* Disable this if doing a local background,
4192 * TODO: remove this when local background is no longer required.
4193 */
4194 if (do_local_background != 2)
4195 png_set_swap_alpha(png_ptr);
4196 }
4197
4198 else
4199 format &= ~PNG_FORMAT_FLAG_AFIRST;
4200
4201 change &= ~PNG_FORMAT_FLAG_AFIRST;
4202 }
4203 # endif
4204
4205 /* If the *output* is 16-bit then we need to check for a byte-swap on this
4206 * architecture.
4207 */
4208 if (linear != 0)
4209 {
4210 png_uint_16 le = 0x0001;
4211
4212 if ((*(png_const_bytep) & le) != 0)
4213 png_set_swap(png_ptr);
4214 }
4215
4216 /* If change is not now 0 some transformation is missing - error out. */
4217 if (change != 0)
4218 png_error(png_ptr, "png_read_image: unsupported transformation");
4219 }
4220
4221 PNG_SKIP_CHUNKS(png_ptr);
4222
4223 /* Update the 'info' structure and make sure the result is as required; first
4224 * make sure to turn on the interlace handling if it will be required
4225 * (because it can't be turned on *after* the call to png_read_update_info!)
4226 *
4227 * TODO: remove the do_local_background fixup below.
4228 */
4229 if (do_local_compose == 0 && do_local_background != 2)
4230 passes = png_set_interlace_handling(png_ptr);
4231
4232 png_read_update_info(png_ptr, info_ptr);
4233
4234 {
4235 png_uint_32 info_format = 0;
4236
4237 if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
4238 info_format |= PNG_FORMAT_FLAG_COLOR;
4239
4240 if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
4241 {
4242 /* do_local_compose removes this channel below. */
4243 if (do_local_compose == 0)
4244 {
4245 /* do_local_background does the same if required. */
4246 if (do_local_background != 2 ||
4247 (format & PNG_FORMAT_FLAG_ALPHA) != 0)
4248 info_format |= PNG_FORMAT_FLAG_ALPHA;
4249 }
4250 }
4251
4252 else if (do_local_compose != 0) /* internal error */
4253 png_error(png_ptr, "png_image_read: alpha channel lost");
4254
4255 if ((format & PNG_FORMAT_FLAG_ASSOCIATED_ALPHA) != 0) {
4256 info_format |= PNG_FORMAT_FLAG_ASSOCIATED_ALPHA;
4257 }
4258
4259 if (info_ptr->bit_depth == 16)
4260 info_format |= PNG_FORMAT_FLAG_LINEAR;
4261
4262 #ifdef PNG_FORMAT_BGR_SUPPORTED
4263 if ((png_ptr->transformations & PNG_BGR) != 0)
4264 info_format |= PNG_FORMAT_FLAG_BGR;
4265 #endif
4266
4267 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
4268 if (do_local_background == 2)
4269 {
4270 if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
4271 info_format |= PNG_FORMAT_FLAG_AFIRST;
4272 }
4273
4274 if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0 ||
4275 ((png_ptr->transformations & PNG_ADD_ALPHA) != 0 &&
4276 (png_ptr->flags & PNG_FLAG_FILLER_AFTER) == 0))
4277 {
4278 if (do_local_background == 2)
4279 png_error(png_ptr, "unexpected alpha swap transformation");
4280
4281 info_format |= PNG_FORMAT_FLAG_AFIRST;
4282 }
4283 # endif
4284
4285 /* This is actually an internal error. */
4286 if (info_format != format)
4287 png_error(png_ptr, "png_read_image: invalid transformations");
4288 }
4289
4290 /* Now read the rows. If do_local_compose is set then it is necessary to use
4291 * a local row buffer. The output will be GA, RGBA or BGRA and must be
4292 * converted to G, RGB or BGR as appropriate. The 'local_row' member of the
4293 * display acts as a flag.
4294 */
4295 {
4296 png_voidp first_row = display->buffer;
4297 ptrdiff_t row_bytes = display->row_stride;
4298
4299 if (linear != 0)
4300 row_bytes *= 2;
4301
4302 /* The following expression is designed to work correctly whether it gives
4303 * a signed or an unsigned result.
4304 */
4305 if (row_bytes < 0)
4306 {
4307 char *ptr = png_voidcast(char*, first_row);
4308 ptr += (image->height-1) * (-row_bytes);
4309 first_row = png_voidcast(png_voidp, ptr);
4310 }
4311
4312 display->first_row = first_row;
4313 display->row_bytes = row_bytes;
4314 }
4315
4316 if (do_local_compose != 0)
4317 {
4318 int result;
4319 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
4320
4321 display->local_row = row;
4322 result = png_safe_execute(image, png_image_read_composite, display);
4323 display->local_row = NULL;
4324 png_free(png_ptr, row);
4325
4326 return result;
4327 }
4328
4329 else if (do_local_background == 2)
4330 {
4331 int result;
4332 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
4333
4334 display->local_row = row;
4335 result = png_safe_execute(image, png_image_read_background, display);
4336 display->local_row = NULL;
4337 png_free(png_ptr, row);
4338
4339 return result;
4340 }
4341
4342 else
4343 {
4344 png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes;
4345
4346 while (--passes >= 0)
4347 {
4348 png_uint_32 y = image->height;
4349 png_bytep row = png_voidcast(png_bytep, display->first_row);
4350
4351 for (; y > 0; --y)
4352 {
4353 png_read_row(png_ptr, row, NULL);
4354 row += row_bytes;
4355 }
4356 }
4357
4358 return 1;
4359 }
4360 }
4361
4362 int PNGAPI
png_image_finish_read(png_imagep image,png_const_colorp background,void * buffer,png_int_32 row_stride,void * colormap)4363 png_image_finish_read(png_imagep image, png_const_colorp background,
4364 void *buffer, png_int_32 row_stride, void *colormap)
4365 {
4366 if (image != NULL && image->version == PNG_IMAGE_VERSION)
4367 {
4368 /* Check for row_stride overflow. This check is not performed on the
4369 * original PNG format because it may not occur in the output PNG format
4370 * and libpng deals with the issues of reading the original.
4371 */
4372 unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
4373
4374 /* The following checks just the 'row_stride' calculation to ensure it
4375 * fits in a signed 32-bit value. Because channels/components can be
4376 * either 1 or 2 bytes in size the length of a row can still overflow 32
4377 * bits; this is just to verify that the 'row_stride' argument can be
4378 * represented.
4379 */
4380 if (image->width <= 0x7fffffffU/channels) /* no overflow */
4381 {
4382 png_uint_32 check;
4383 png_uint_32 png_row_stride = image->width * channels;
4384
4385 if (row_stride == 0)
4386 row_stride = (png_int_32)/*SAFE*/png_row_stride;
4387
4388 if (row_stride < 0)
4389 check = (png_uint_32)(-row_stride);
4390
4391 else
4392 check = (png_uint_32)row_stride;
4393
4394 /* This verifies 'check', the absolute value of the actual stride
4395 * passed in and detects overflow in the application calculation (i.e.
4396 * if the app did actually pass in a non-zero 'row_stride'.
4397 */
4398 if (image->opaque != NULL && buffer != NULL && check >= png_row_stride)
4399 {
4400 /* Now check for overflow of the image buffer calculation; this
4401 * limits the whole image size to 32 bits for API compatibility with
4402 * the current, 32-bit, PNG_IMAGE_BUFFER_SIZE macro.
4403 *
4404 * The PNG_IMAGE_BUFFER_SIZE macro is:
4405 *
4406 * (PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)*height*(row_stride))
4407 *
4408 * And the component size is always 1 or 2, so make sure that the
4409 * number of *bytes* that the application is saying are available
4410 * does actually fit into a 32-bit number.
4411 *
4412 * NOTE: this will be changed in 1.7 because PNG_IMAGE_BUFFER_SIZE
4413 * will be changed to use png_alloc_size_t; bigger images can be
4414 * accommodated on 64-bit systems.
4415 */
4416 if (image->height <=
4417 0xffffffffU/PNG_IMAGE_PIXEL_COMPONENT_SIZE(image->format)/check)
4418 {
4419 if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 ||
4420 (image->colormap_entries > 0 && colormap != NULL))
4421 {
4422 int result;
4423 png_image_read_control display;
4424
4425 memset(&display, 0, (sizeof display));
4426 display.image = image;
4427 display.buffer = buffer;
4428 display.row_stride = row_stride;
4429 display.colormap = colormap;
4430 display.background = background;
4431 display.local_row = NULL;
4432
4433 /* Choose the correct 'end' routine; for the color-map case
4434 * all the setup has already been done.
4435 */
4436 if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0)
4437 result =
4438 png_safe_execute(image,
4439 png_image_read_colormap, &display) &&
4440 png_safe_execute(image,
4441 png_image_read_colormapped, &display);
4442
4443 else
4444 result =
4445 png_safe_execute(image,
4446 png_image_read_direct, &display);
4447
4448 png_image_free(image);
4449 return result;
4450 }
4451
4452 else
4453 return png_image_error(image,
4454 "png_image_finish_read[color-map]: no color-map");
4455 }
4456
4457 else
4458 return png_image_error(image,
4459 "png_image_finish_read: image too large");
4460 }
4461
4462 else
4463 return png_image_error(image,
4464 "png_image_finish_read: invalid argument");
4465 }
4466
4467 else
4468 return png_image_error(image,
4469 "png_image_finish_read: row_stride too large");
4470 }
4471
4472 else if (image != NULL)
4473 return png_image_error(image,
4474 "png_image_finish_read: damaged PNG_IMAGE_VERSION");
4475
4476 return 0;
4477 }
4478
4479 #endif /* SIMPLIFIED_READ */
4480 #endif /* READ */
4481