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fix for openout message (HH)
[luatex.git] / source / libs / libpng / libpng-1.6.16 / pngread.c
blob87a789157bb3cb6758bf0c1a27548750f01757dc
1
2 /* pngread.c - read a PNG file
3 *
4 * Last changed in libpng 1.6.15 [November 20, 2014]
5 * Copyright (c) 1998-2014 Glenn Randers-Pehrson
6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
8 *
9 * This code is released under the libpng license.
10 * For conditions of distribution and use, see the disclaimer
11 * and license in png.h
12 *
13 * This file contains 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 png_ptr->IDAT_read_size = PNG_IDAT_READ_SIZE;
58 # endif
59
60 # ifdef PNG_BENIGN_READ_ERRORS_SUPPORTED
61 png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN;
62
63 /* In stable builds only warn if an application error can be completely
64 * handled.
65 */
66 # if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC
67 png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN;
68 # endif
69 # endif
70
71 /* TODO: delay this, it can be done in png_init_io (if the app doesn't
72 * do it itself) avoiding setting the default function if it is not
73 * required.
74 */
75 png_set_read_fn(png_ptr, NULL, NULL);
76 }
77
78 return png_ptr;
79 }
80
81
82 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
83 /* Read the information before the actual image data. This has been
84 * changed in v0.90 to allow reading a file that already has the magic
85 * bytes read from the stream. You can tell libpng how many bytes have
86 * been read from the beginning of the stream (up to the maximum of 8)
87 * via png_set_sig_bytes(), and we will only check the remaining bytes
88 * here. The application can then have access to the signature bytes we
89 * read if it is determined that this isn't a valid PNG file.
90 */
91 void PNGAPI
92 png_read_info(png_structrp png_ptr, png_inforp info_ptr)
93 {
94 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
95 int keep;
96 #endif
97
98 png_debug(1, "in png_read_info");
99
100 if (png_ptr == NULL || info_ptr == NULL)
101 return;
102
103 /* Read and check the PNG file signature. */
104 png_read_sig(png_ptr, info_ptr);
105
106 for (;;)
107 {
108 png_uint_32 length = png_read_chunk_header(png_ptr);
109 png_uint_32 chunk_name = png_ptr->chunk_name;
110
111 /* IDAT logic needs to happen here to simplify getting the two flags
112 * right.
113 */
114 if (chunk_name == png_IDAT)
115 {
116 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
117 png_chunk_error(png_ptr, "Missing IHDR before IDAT");
118
119 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
120 (png_ptr->mode & PNG_HAVE_PLTE) == 0)
121 png_chunk_error(png_ptr, "Missing PLTE before IDAT");
122
123 else if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
124 png_chunk_benign_error(png_ptr, "Too many IDATs found");
125
126 png_ptr->mode |= PNG_HAVE_IDAT;
127 }
128
129 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
130 png_ptr->mode |= PNG_AFTER_IDAT;
131
132 /* This should be a binary subdivision search or a hash for
133 * matching the chunk name rather than a linear search.
134 */
135 if (chunk_name == png_IHDR)
136 png_handle_IHDR(png_ptr, info_ptr, length);
137
138 else if (chunk_name == png_IEND)
139 png_handle_IEND(png_ptr, info_ptr, length);
140
141 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
142 else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
143 {
144 png_handle_unknown(png_ptr, info_ptr, length, keep);
145
146 if (chunk_name == png_PLTE)
147 png_ptr->mode |= PNG_HAVE_PLTE;
148
149 else if (chunk_name == png_IDAT)
150 {
151 png_ptr->idat_size = 0; /* It has been consumed */
152 break;
153 }
154 }
155 #endif
156 else if (chunk_name == png_PLTE)
157 png_handle_PLTE(png_ptr, info_ptr, length);
158
159 else if (chunk_name == png_IDAT)
160 {
161 png_ptr->idat_size = length;
162 break;
163 }
164
165 #ifdef PNG_READ_bKGD_SUPPORTED
166 else if (chunk_name == png_bKGD)
167 png_handle_bKGD(png_ptr, info_ptr, length);
168 #endif
169
170 #ifdef PNG_READ_cHRM_SUPPORTED
171 else if (chunk_name == png_cHRM)
172 png_handle_cHRM(png_ptr, info_ptr, length);
173 #endif
174
175 #ifdef PNG_READ_gAMA_SUPPORTED
176 else if (chunk_name == png_gAMA)
177 png_handle_gAMA(png_ptr, info_ptr, length);
178 #endif
179
180 #ifdef PNG_READ_hIST_SUPPORTED
181 else if (chunk_name == png_hIST)
182 png_handle_hIST(png_ptr, info_ptr, length);
183 #endif
184
185 #ifdef PNG_READ_oFFs_SUPPORTED
186 else if (chunk_name == png_oFFs)
187 png_handle_oFFs(png_ptr, info_ptr, length);
188 #endif
189
190 #ifdef PNG_READ_pCAL_SUPPORTED
191 else if (chunk_name == png_pCAL)
192 png_handle_pCAL(png_ptr, info_ptr, length);
193 #endif
194
195 #ifdef PNG_READ_sCAL_SUPPORTED
196 else if (chunk_name == png_sCAL)
197 png_handle_sCAL(png_ptr, info_ptr, length);
198 #endif
199
200 #ifdef PNG_READ_pHYs_SUPPORTED
201 else if (chunk_name == png_pHYs)
202 png_handle_pHYs(png_ptr, info_ptr, length);
203 #endif
204
205 #ifdef PNG_READ_sBIT_SUPPORTED
206 else if (chunk_name == png_sBIT)
207 png_handle_sBIT(png_ptr, info_ptr, length);
208 #endif
209
210 #ifdef PNG_READ_sRGB_SUPPORTED
211 else if (chunk_name == png_sRGB)
212 png_handle_sRGB(png_ptr, info_ptr, length);
213 #endif
214
215 #ifdef PNG_READ_iCCP_SUPPORTED
216 else if (chunk_name == png_iCCP)
217 png_handle_iCCP(png_ptr, info_ptr, length);
218 #endif
219
220 #ifdef PNG_READ_sPLT_SUPPORTED
221 else if (chunk_name == png_sPLT)
222 png_handle_sPLT(png_ptr, info_ptr, length);
223 #endif
224
225 #ifdef PNG_READ_tEXt_SUPPORTED
226 else if (chunk_name == png_tEXt)
227 png_handle_tEXt(png_ptr, info_ptr, length);
228 #endif
229
230 #ifdef PNG_READ_tIME_SUPPORTED
231 else if (chunk_name == png_tIME)
232 png_handle_tIME(png_ptr, info_ptr, length);
233 #endif
234
235 #ifdef PNG_READ_tRNS_SUPPORTED
236 else if (chunk_name == png_tRNS)
237 png_handle_tRNS(png_ptr, info_ptr, length);
238 #endif
239
240 #ifdef PNG_READ_zTXt_SUPPORTED
241 else if (chunk_name == png_zTXt)
242 png_handle_zTXt(png_ptr, info_ptr, length);
243 #endif
244
245 #ifdef PNG_READ_iTXt_SUPPORTED
246 else if (chunk_name == png_iTXt)
247 png_handle_iTXt(png_ptr, info_ptr, length);
248 #endif
249
250 else
251 png_handle_unknown(png_ptr, info_ptr, length,
252 PNG_HANDLE_CHUNK_AS_DEFAULT);
253 }
254 }
255 #endif /* SEQUENTIAL_READ */
256
257 /* Optional call to update the users info_ptr structure */
258 void PNGAPI
259 png_read_update_info(png_structrp png_ptr, png_inforp info_ptr)
260 {
261 png_debug(1, "in png_read_update_info");
262
263 if (png_ptr != NULL)
264 {
265 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
266 {
267 png_read_start_row(png_ptr);
268
269 # ifdef PNG_READ_TRANSFORMS_SUPPORTED
270 png_read_transform_info(png_ptr, info_ptr);
271 # else
272 PNG_UNUSED(info_ptr)
273 # endif
274 }
275
276 /* New in 1.6.0 this avoids the bug of doing the initializations twice */
277 else
278 png_app_error(png_ptr,
279 "png_read_update_info/png_start_read_image: duplicate call");
280 }
281 }
282
283 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
284 /* Initialize palette, background, etc, after transformations
285 * are set, but before any reading takes place. This allows
286 * the user to obtain a gamma-corrected palette, for example.
287 * If the user doesn't call this, we will do it ourselves.
288 */
289 void PNGAPI
290 png_start_read_image(png_structrp png_ptr)
291 {
292 png_debug(1, "in png_start_read_image");
293
294 if (png_ptr != NULL)
295 {
296 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
297 png_read_start_row(png_ptr);
298
299 /* New in 1.6.0 this avoids the bug of doing the initializations twice */
300 else
301 png_app_error(png_ptr,
302 "png_start_read_image/png_read_update_info: duplicate call");
303 }
304 }
305 #endif /* SEQUENTIAL_READ */
306
307 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
308 #ifdef PNG_MNG_FEATURES_SUPPORTED
309 /* Undoes intrapixel differencing,
310 * NOTE: this is apparently only supported in the 'sequential' reader.
311 */
312 static void
313 png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
314 {
315 png_debug(1, "in png_do_read_intrapixel");
316
317 if (
318 (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
319 {
320 int bytes_per_pixel;
321 png_uint_32 row_width = row_info->width;
322
323 if (row_info->bit_depth == 8)
324 {
325 png_bytep rp;
326 png_uint_32 i;
327
328 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
329 bytes_per_pixel = 3;
330
331 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
332 bytes_per_pixel = 4;
333
334 else
335 return;
336
337 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
338 {
339 *(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff);
340 *(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff);
341 }
342 }
343 else if (row_info->bit_depth == 16)
344 {
345 png_bytep rp;
346 png_uint_32 i;
347
348 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
349 bytes_per_pixel = 6;
350
351 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
352 bytes_per_pixel = 8;
353
354 else
355 return;
356
357 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
358 {
359 png_uint_32 s0 = (*(rp ) << 8) | *(rp + 1);
360 png_uint_32 s1 = (*(rp + 2) << 8) | *(rp + 3);
361 png_uint_32 s2 = (*(rp + 4) << 8) | *(rp + 5);
362 png_uint_32 red = (s0 + s1 + 65536) & 0xffff;
363 png_uint_32 blue = (s2 + s1 + 65536) & 0xffff;
364 *(rp ) = (png_byte)((red >> 8) & 0xff);
365 *(rp + 1) = (png_byte)(red & 0xff);
366 *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
367 *(rp + 5) = (png_byte)(blue & 0xff);
368 }
369 }
370 }
371 }
372 #endif /* MNG_FEATURES */
373
374 void PNGAPI
375 png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)
376 {
377 png_row_info row_info;
378
379 if (png_ptr == NULL)
380 return;
381
382 png_debug2(1, "in png_read_row (row %lu, pass %d)",
383 (unsigned long)png_ptr->row_number, png_ptr->pass);
384
385 /* png_read_start_row sets the information (in particular iwidth) for this
386 * interlace pass.
387 */
388 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
389 png_read_start_row(png_ptr);
390
391 /* 1.5.6: row_info moved out of png_struct to a local here. */
392 row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
393 row_info.color_type = png_ptr->color_type;
394 row_info.bit_depth = png_ptr->bit_depth;
395 row_info.channels = png_ptr->channels;
396 row_info.pixel_depth = png_ptr->pixel_depth;
397 row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
398
399 #ifdef PNG_WARNINGS_SUPPORTED
400 if (png_ptr->row_number == 0 && png_ptr->pass == 0)
401 {
402 /* Check for transforms that have been set but were defined out */
403 #if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED)
404 if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
405 png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined");
406 #endif
407
408 #if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED)
409 if ((png_ptr->transformations & PNG_FILLER) != 0)
410 png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined");
411 #endif
412
413 #if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
414 !defined(PNG_READ_PACKSWAP_SUPPORTED)
415 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
416 png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined");
417 #endif
418
419 #if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED)
420 if ((png_ptr->transformations & PNG_PACK) != 0)
421 png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined");
422 #endif
423
424 #if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED)
425 if ((png_ptr->transformations & PNG_SHIFT) != 0)
426 png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined");
427 #endif
428
429 #if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED)
430 if ((png_ptr->transformations & PNG_BGR) != 0)
431 png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined");
432 #endif
433
434 #if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED)
435 if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
436 png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined");
437 #endif
438 }
439 #endif /* WARNINGS */
440
441 #ifdef PNG_READ_INTERLACING_SUPPORTED
442 /* If interlaced and we do not need a new row, combine row and return.
443 * Notice that the pixels we have from previous rows have been transformed
444 * already; we can only combine like with like (transformed or
445 * untransformed) and, because of the libpng API for interlaced images, this
446 * means we must transform before de-interlacing.
447 */
448 if (png_ptr->interlaced != 0 &&
449 (png_ptr->transformations & PNG_INTERLACE) != 0)
450 {
451 switch (png_ptr->pass)
452 {
453 case 0:
454 if (png_ptr->row_number & 0x07)
455 {
456 if (dsp_row != NULL)
457 png_combine_row(png_ptr, dsp_row, 1/*display*/);
458 png_read_finish_row(png_ptr);
459 return;
460 }
461 break;
462
463 case 1:
464 if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
465 {
466 if (dsp_row != NULL)
467 png_combine_row(png_ptr, dsp_row, 1/*display*/);
468
469 png_read_finish_row(png_ptr);
470 return;
471 }
472 break;
473
474 case 2:
475 if ((png_ptr->row_number & 0x07) != 4)
476 {
477 if (dsp_row != NULL && (png_ptr->row_number & 4))
478 png_combine_row(png_ptr, dsp_row, 1/*display*/);
479
480 png_read_finish_row(png_ptr);
481 return;
482 }
483 break;
484
485 case 3:
486 if ((png_ptr->row_number & 3) || png_ptr->width < 3)
487 {
488 if (dsp_row != NULL)
489 png_combine_row(png_ptr, dsp_row, 1/*display*/);
490
491 png_read_finish_row(png_ptr);
492 return;
493 }
494 break;
495
496 case 4:
497 if ((png_ptr->row_number & 3) != 2)
498 {
499 if (dsp_row != NULL && (png_ptr->row_number & 2))
500 png_combine_row(png_ptr, dsp_row, 1/*display*/);
501
502 png_read_finish_row(png_ptr);
503 return;
504 }
505 break;
506
507 case 5:
508 if ((png_ptr->row_number & 1) || png_ptr->width < 2)
509 {
510 if (dsp_row != NULL)
511 png_combine_row(png_ptr, dsp_row, 1/*display*/);
512
513 png_read_finish_row(png_ptr);
514 return;
515 }
516 break;
517
518 default:
519 case 6:
520 if ((png_ptr->row_number & 1) == 0)
521 {
522 png_read_finish_row(png_ptr);
523 return;
524 }
525 break;
526 }
527 }
528 #endif
529
530 if ((png_ptr->mode & PNG_HAVE_IDAT) == 0)
531 png_error(png_ptr, "Invalid attempt to read row data");
532
533 /* Fill the row with IDAT data: */
534 png_read_IDAT_data(png_ptr, png_ptr->row_buf, row_info.rowbytes + 1);
535
536 if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
537 {
538 if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
539 png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
540 png_ptr->prev_row + 1, png_ptr->row_buf[0]);
541 else
542 png_error(png_ptr, "bad adaptive filter value");
543 }
544
545 /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
546 * 1.5.6, while the buffer really is this big in current versions of libpng
547 * it may not be in the future, so this was changed just to copy the
548 * interlaced count:
549 */
550 memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
551
552 #ifdef PNG_MNG_FEATURES_SUPPORTED
553 if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
554 (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
555 {
556 /* Intrapixel differencing */
557 png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1);
558 }
559 #endif
560
561 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
562 if (png_ptr->transformations)
563 png_do_read_transformations(png_ptr, &row_info);
564 #endif
565
566 /* The transformed pixel depth should match the depth now in row_info. */
567 if (png_ptr->transformed_pixel_depth == 0)
568 {
569 png_ptr->transformed_pixel_depth = row_info.pixel_depth;
570 if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
571 png_error(png_ptr, "sequential row overflow");
572 }
573
574 else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
575 png_error(png_ptr, "internal sequential row size calculation error");
576
577 #ifdef PNG_READ_INTERLACING_SUPPORTED
578 /* Expand interlaced rows to full size */
579 if (png_ptr->interlaced != 0 &&
580 (png_ptr->transformations & PNG_INTERLACE) != 0)
581 {
582 if (png_ptr->pass < 6)
583 png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
584 png_ptr->transformations);
585
586 if (dsp_row != NULL)
587 png_combine_row(png_ptr, dsp_row, 1/*display*/);
588
589 if (row != NULL)
590 png_combine_row(png_ptr, row, 0/*row*/);
591 }
592
593 else
594 #endif
595 {
596 if (row != NULL)
597 png_combine_row(png_ptr, row, -1/*ignored*/);
598
599 if (dsp_row != NULL)
600 png_combine_row(png_ptr, dsp_row, -1/*ignored*/);
601 }
602 png_read_finish_row(png_ptr);
603
604 if (png_ptr->read_row_fn != NULL)
605 (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
606
607 }
608 #endif /* SEQUENTIAL_READ */
609
610 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
611 /* Read one or more rows of image data. If the image is interlaced,
612 * and png_set_interlace_handling() has been called, the rows need to
613 * contain the contents of the rows from the previous pass. If the
614 * image has alpha or transparency, and png_handle_alpha()[*] has been
615 * called, the rows contents must be initialized to the contents of the
616 * screen.
617 *
618 * "row" holds the actual image, and pixels are placed in it
619 * as they arrive. If the image is displayed after each pass, it will
620 * appear to "sparkle" in. "display_row" can be used to display a
621 * "chunky" progressive image, with finer detail added as it becomes
622 * available. If you do not want this "chunky" display, you may pass
623 * NULL for display_row. If you do not want the sparkle display, and
624 * you have not called png_handle_alpha(), you may pass NULL for rows.
625 * If you have called png_handle_alpha(), and the image has either an
626 * alpha channel or a transparency chunk, you must provide a buffer for
627 * rows. In this case, you do not have to provide a display_row buffer
628 * also, but you may. If the image is not interlaced, or if you have
629 * not called png_set_interlace_handling(), the display_row buffer will
630 * be ignored, so pass NULL to it.
631 *
632 * [*] png_handle_alpha() does not exist yet, as of this version of libpng
633 */
634
635 void PNGAPI
636 png_read_rows(png_structrp png_ptr, png_bytepp row,
637 png_bytepp display_row, png_uint_32 num_rows)
638 {
639 png_uint_32 i;
640 png_bytepp rp;
641 png_bytepp dp;
642
643 png_debug(1, "in png_read_rows");
644
645 if (png_ptr == NULL)
646 return;
647
648 rp = row;
649 dp = display_row;
650 if (rp != NULL && dp != NULL)
651 for (i = 0; i < num_rows; i++)
652 {
653 png_bytep rptr = *rp++;
654 png_bytep dptr = *dp++;
655
656 png_read_row(png_ptr, rptr, dptr);
657 }
658
659 else if (rp != NULL)
660 for (i = 0; i < num_rows; i++)
661 {
662 png_bytep rptr = *rp;
663 png_read_row(png_ptr, rptr, NULL);
664 rp++;
665 }
666
667 else if (dp != NULL)
668 for (i = 0; i < num_rows; i++)
669 {
670 png_bytep dptr = *dp;
671 png_read_row(png_ptr, NULL, dptr);
672 dp++;
673 }
674 }
675 #endif /* SEQUENTIAL_READ */
676
677 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
678 /* Read the entire image. If the image has an alpha channel or a tRNS
679 * chunk, and you have called png_handle_alpha()[*], you will need to
680 * initialize the image to the current image that PNG will be overlaying.
681 * We set the num_rows again here, in case it was incorrectly set in
682 * png_read_start_row() by a call to png_read_update_info() or
683 * png_start_read_image() if png_set_interlace_handling() wasn't called
684 * prior to either of these functions like it should have been. You can
685 * only call this function once. If you desire to have an image for
686 * each pass of a interlaced image, use png_read_rows() instead.
687 *
688 * [*] png_handle_alpha() does not exist yet, as of this version of libpng
689 */
690 void PNGAPI
691 png_read_image(png_structrp png_ptr, png_bytepp image)
692 {
693 png_uint_32 i, image_height;
694 int pass, j;
695 png_bytepp rp;
696
697 png_debug(1, "in png_read_image");
698
699 if (png_ptr == NULL)
700 return;
701
702 #ifdef PNG_READ_INTERLACING_SUPPORTED
703 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
704 {
705 pass = png_set_interlace_handling(png_ptr);
706 /* And make sure transforms are initialized. */
707 png_start_read_image(png_ptr);
708 }
709 else
710 {
711 if (png_ptr->interlaced != 0 &&
712 (png_ptr->transformations & PNG_INTERLACE) == 0)
713 {
714 /* Caller called png_start_read_image or png_read_update_info without
715 * first turning on the PNG_INTERLACE transform. We can fix this here,
716 * but the caller should do it!
717 */
718 png_warning(png_ptr, "Interlace handling should be turned on when "
719 "using png_read_image");
720 /* Make sure this is set correctly */
721 png_ptr->num_rows = png_ptr->height;
722 }
723
724 /* Obtain the pass number, which also turns on the PNG_INTERLACE flag in
725 * the above error case.
726 */
727 pass = png_set_interlace_handling(png_ptr);
728 }
729 #else
730 if (png_ptr->interlaced)
731 png_error(png_ptr,
732 "Cannot read interlaced image -- interlace handler disabled");
733
734 pass = 1;
735 #endif
736
737 image_height=png_ptr->height;
738
739 for (j = 0; j < pass; j++)
740 {
741 rp = image;
742 for (i = 0; i < image_height; i++)
743 {
744 png_read_row(png_ptr, *rp, NULL);
745 rp++;
746 }
747 }
748 }
749 #endif /* SEQUENTIAL_READ */
750
751 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
752 /* Read the end of the PNG file. Will not read past the end of the
753 * file, will verify the end is accurate, and will read any comments
754 * or time information at the end of the file, if info is not NULL.
755 */
756 void PNGAPI
757 png_read_end(png_structrp png_ptr, png_inforp info_ptr)
758 {
759 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
760 int keep;
761 #endif
762
763 png_debug(1, "in png_read_end");
764
765 if (png_ptr == NULL)
766 return;
767
768 /* If png_read_end is called in the middle of reading the rows there may
769 * still be pending IDAT data and an owned zstream. Deal with this here.
770 */
771 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
772 if (png_chunk_unknown_handling(png_ptr, png_IDAT) == 0)
773 #endif
774 png_read_finish_IDAT(png_ptr);
775
776 #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
777 /* Report invalid palette index; added at libng-1.5.10 */
778 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
779 png_ptr->num_palette_max > png_ptr->num_palette)
780 png_benign_error(png_ptr, "Read palette index exceeding num_palette");
781 #endif
782
783 do
784 {
785 png_uint_32 length = png_read_chunk_header(png_ptr);
786 png_uint_32 chunk_name = png_ptr->chunk_name;
787
788 if (chunk_name == png_IEND)
789 png_handle_IEND(png_ptr, info_ptr, length);
790
791 else if (chunk_name == png_IHDR)
792 png_handle_IHDR(png_ptr, info_ptr, length);
793
794 else if (info_ptr == NULL)
795 png_crc_finish(png_ptr, length);
796
797 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
798 else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
799 {
800 if (chunk_name == png_IDAT)
801 {
802 if ((length > 0) ||
803 (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
804 png_benign_error(png_ptr, "Too many IDATs found");
805 }
806 png_handle_unknown(png_ptr, info_ptr, length, keep);
807 if (chunk_name == png_PLTE)
808 png_ptr->mode |= PNG_HAVE_PLTE;
809 }
810 #endif
811
812 else if (chunk_name == png_IDAT)
813 {
814 /* Zero length IDATs are legal after the last IDAT has been
815 * read, but not after other chunks have been read.
816 */
817 if ((length > 0) ||
818 (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
819 png_benign_error(png_ptr, "Too many IDATs found");
820
821 png_crc_finish(png_ptr, length);
822 }
823 else if (chunk_name == png_PLTE)
824 png_handle_PLTE(png_ptr, info_ptr, length);
825
826 #ifdef PNG_READ_bKGD_SUPPORTED
827 else if (chunk_name == png_bKGD)
828 png_handle_bKGD(png_ptr, info_ptr, length);
829 #endif
830
831 #ifdef PNG_READ_cHRM_SUPPORTED
832 else if (chunk_name == png_cHRM)
833 png_handle_cHRM(png_ptr, info_ptr, length);
834 #endif
835
836 #ifdef PNG_READ_gAMA_SUPPORTED
837 else if (chunk_name == png_gAMA)
838 png_handle_gAMA(png_ptr, info_ptr, length);
839 #endif
840
841 #ifdef PNG_READ_hIST_SUPPORTED
842 else if (chunk_name == png_hIST)
843 png_handle_hIST(png_ptr, info_ptr, length);
844 #endif
845
846 #ifdef PNG_READ_oFFs_SUPPORTED
847 else if (chunk_name == png_oFFs)
848 png_handle_oFFs(png_ptr, info_ptr, length);
849 #endif
850
851 #ifdef PNG_READ_pCAL_SUPPORTED
852 else if (chunk_name == png_pCAL)
853 png_handle_pCAL(png_ptr, info_ptr, length);
854 #endif
855
856 #ifdef PNG_READ_sCAL_SUPPORTED
857 else if (chunk_name == png_sCAL)
858 png_handle_sCAL(png_ptr, info_ptr, length);
859 #endif
860
861 #ifdef PNG_READ_pHYs_SUPPORTED
862 else if (chunk_name == png_pHYs)
863 png_handle_pHYs(png_ptr, info_ptr, length);
864 #endif
865
866 #ifdef PNG_READ_sBIT_SUPPORTED
867 else if (chunk_name == png_sBIT)
868 png_handle_sBIT(png_ptr, info_ptr, length);
869 #endif
870
871 #ifdef PNG_READ_sRGB_SUPPORTED
872 else if (chunk_name == png_sRGB)
873 png_handle_sRGB(png_ptr, info_ptr, length);
874 #endif
875
876 #ifdef PNG_READ_iCCP_SUPPORTED
877 else if (chunk_name == png_iCCP)
878 png_handle_iCCP(png_ptr, info_ptr, length);
879 #endif
880
881 #ifdef PNG_READ_sPLT_SUPPORTED
882 else if (chunk_name == png_sPLT)
883 png_handle_sPLT(png_ptr, info_ptr, length);
884 #endif
885
886 #ifdef PNG_READ_tEXt_SUPPORTED
887 else if (chunk_name == png_tEXt)
888 png_handle_tEXt(png_ptr, info_ptr, length);
889 #endif
890
891 #ifdef PNG_READ_tIME_SUPPORTED
892 else if (chunk_name == png_tIME)
893 png_handle_tIME(png_ptr, info_ptr, length);
894 #endif
895
896 #ifdef PNG_READ_tRNS_SUPPORTED
897 else if (chunk_name == png_tRNS)
898 png_handle_tRNS(png_ptr, info_ptr, length);
899 #endif
900
901 #ifdef PNG_READ_zTXt_SUPPORTED
902 else if (chunk_name == png_zTXt)
903 png_handle_zTXt(png_ptr, info_ptr, length);
904 #endif
905
906 #ifdef PNG_READ_iTXt_SUPPORTED
907 else if (chunk_name == png_iTXt)
908 png_handle_iTXt(png_ptr, info_ptr, length);
909 #endif
910
911 else
912 png_handle_unknown(png_ptr, info_ptr, length,
913 PNG_HANDLE_CHUNK_AS_DEFAULT);
914 } while ((png_ptr->mode & PNG_HAVE_IEND) == 0);
915 }
916 #endif /* SEQUENTIAL_READ */
917
918 /* Free all memory used in the read struct */
919 static void
920 png_read_destroy(png_structrp png_ptr)
921 {
922 png_debug(1, "in png_read_destroy");
923
924 #ifdef PNG_READ_GAMMA_SUPPORTED
925 png_destroy_gamma_table(png_ptr);
926 #endif
927
928 png_free(png_ptr, png_ptr->big_row_buf);
929 png_ptr->big_row_buf = NULL;
930 png_free(png_ptr, png_ptr->big_prev_row);
931 png_ptr->big_prev_row = NULL;
932 png_free(png_ptr, png_ptr->read_buffer);
933 png_ptr->read_buffer = NULL;
934
935 #ifdef PNG_READ_QUANTIZE_SUPPORTED
936 png_free(png_ptr, png_ptr->palette_lookup);
937 png_ptr->palette_lookup = NULL;
938 png_free(png_ptr, png_ptr->quantize_index);
939 png_ptr->quantize_index = NULL;
940 #endif
941
942 if ((png_ptr->free_me & PNG_FREE_PLTE) != 0)
943 {
944 png_zfree(png_ptr, png_ptr->palette);
945 png_ptr->palette = NULL;
946 }
947 png_ptr->free_me &= ~PNG_FREE_PLTE;
948
949 #if defined(PNG_tRNS_SUPPORTED) || \
950 defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
951 if ((png_ptr->free_me & PNG_FREE_TRNS) != 0)
952 {
953 png_free(png_ptr, png_ptr->trans_alpha);
954 png_ptr->trans_alpha = NULL;
955 }
956 png_ptr->free_me &= ~PNG_FREE_TRNS;
957 #endif
958
959 inflateEnd(&png_ptr->zstream);
960
961 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
962 png_free(png_ptr, png_ptr->save_buffer);
963 png_ptr->save_buffer = NULL;
964 #endif
965
966 #if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) && \
967 defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
968 png_free(png_ptr, png_ptr->unknown_chunk.data);
969 png_ptr->unknown_chunk.data = NULL;
970 #endif
971
972 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
973 png_free(png_ptr, png_ptr->chunk_list);
974 png_ptr->chunk_list = NULL;
975 #endif
976
977 /* NOTE: the 'setjmp' buffer may still be allocated and the memory and error
978 * callbacks are still set at this point. They are required to complete the
979 * destruction of the png_struct itself.
980 */
981 }
982
983 /* Free all memory used by the read */
984 void PNGAPI
985 png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
986 png_infopp end_info_ptr_ptr)
987 {
988 png_structrp png_ptr = NULL;
989
990 png_debug(1, "in png_destroy_read_struct");
991
992 if (png_ptr_ptr != NULL)
993 png_ptr = *png_ptr_ptr;
994
995 if (png_ptr == NULL)
996 return;
997
998 /* libpng 1.6.0: use the API to destroy info structs to ensure consistent
999 * behavior. Prior to 1.6.0 libpng did extra 'info' destruction in this API.
1000 * The extra was, apparently, unnecessary yet this hides memory leak bugs.
1001 */
1002 png_destroy_info_struct(png_ptr, end_info_ptr_ptr);
1003 png_destroy_info_struct(png_ptr, info_ptr_ptr);
1004
1005 *png_ptr_ptr = NULL;
1006 png_read_destroy(png_ptr);
1007 png_destroy_png_struct(png_ptr);
1008 }
1009
1010 void PNGAPI
1011 png_set_read_status_fn(png_structrp png_ptr, png_read_status_ptr read_row_fn)
1012 {
1013 if (png_ptr == NULL)
1014 return;
1015
1016 png_ptr->read_row_fn = read_row_fn;
1017 }
1018
1019
1020 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1021 #ifdef PNG_INFO_IMAGE_SUPPORTED
1022 void PNGAPI
1023 png_read_png(png_structrp png_ptr, png_inforp info_ptr,
1024 int transforms,
1025 voidp params)
1026 {
1027 if (png_ptr == NULL || info_ptr == NULL)
1028 return;
1029
1030 /* png_read_info() gives us all of the information from the
1031 * PNG file before the first IDAT (image data chunk).
1032 */
1033 png_read_info(png_ptr, info_ptr);
1034 if (info_ptr->height > PNG_UINT_32_MAX/(sizeof (png_bytep)))
1035 png_error(png_ptr, "Image is too high to process with png_read_png()");
1036
1037 /* -------------- image transformations start here ------------------- */
1038 /* libpng 1.6.10: add code to cause a png_app_error if a selected TRANSFORM
1039 * is not implemented. This will only happen in de-configured (non-default)
1040 * libpng builds. The results can be unexpected - png_read_png may return
1041 * short or mal-formed rows because the transform is skipped.
1042 */
1043
1044 /* Tell libpng to strip 16-bit/color files down to 8 bits per color.
1045 */
1046 if ((transforms & PNG_TRANSFORM_SCALE_16) != 0)
1047 /* Added at libpng-1.5.4. "strip_16" produces the same result that it
1048 * did in earlier versions, while "scale_16" is now more accurate.
1049 */
1050 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1051 png_set_scale_16(png_ptr);
1052 #else
1053 png_app_error(png_ptr, "PNG_TRANSFORM_SCALE_16 not supported");
1054 #endif
1055
1056 /* If both SCALE and STRIP are required pngrtran will effectively cancel the
1057 * latter by doing SCALE first. This is ok and allows apps not to check for
1058 * which is supported to get the right answer.
1059 */
1060 if ((transforms & PNG_TRANSFORM_STRIP_16) != 0)
1061 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1062 png_set_strip_16(png_ptr);
1063 #else
1064 png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_16 not supported");
1065 #endif
1066
1067 /* Strip alpha bytes from the input data without combining with
1068 * the background (not recommended).
1069 */
1070 if ((transforms & PNG_TRANSFORM_STRIP_ALPHA) != 0)
1071 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1072 png_set_strip_alpha(png_ptr);
1073 #else
1074 png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_ALPHA not supported");
1075 #endif
1076
1077 /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single
1078 * byte into separate bytes (useful for paletted and grayscale images).
1079 */
1080 if ((transforms & PNG_TRANSFORM_PACKING) != 0)
1081 #ifdef PNG_READ_PACK_SUPPORTED
1082 png_set_packing(png_ptr);
1083 #else
1084 png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported");
1085 #endif
1086
1087 /* Change the order of packed pixels to least significant bit first
1088 * (not useful if you are using png_set_packing).
1089 */
1090 if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0)
1091 #ifdef PNG_READ_PACKSWAP_SUPPORTED
1092 png_set_packswap(png_ptr);
1093 #else
1094 png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported");
1095 #endif
1096
1097 /* Expand paletted colors into true RGB triplets
1098 * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel
1099 * Expand paletted or RGB images with transparency to full alpha
1100 * channels so the data will be available as RGBA quartets.
1101 */
1102 if ((transforms & PNG_TRANSFORM_EXPAND) != 0)
1103 #ifdef PNG_READ_EXPAND_SUPPORTED
1104 png_set_expand(png_ptr);
1105 #else
1106 png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND not supported");
1107 #endif
1108
1109 /* We don't handle background color or gamma transformation or quantizing.
1110 */
1111
1112 /* Invert monochrome files to have 0 as white and 1 as black
1113 */
1114 if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0)
1115 #ifdef PNG_READ_INVERT_SUPPORTED
1116 png_set_invert_mono(png_ptr);
1117 #else
1118 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
1119 #endif
1120
1121 /* If you want to shift the pixel values from the range [0,255] or
1122 * [0,65535] to the original [0,7] or [0,31], or whatever range the
1123 * colors were originally in:
1124 */
1125 if ((transforms & PNG_TRANSFORM_SHIFT) != 0)
1126 #ifdef PNG_READ_SHIFT_SUPPORTED
1127 if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
1128 png_set_shift(png_ptr, &info_ptr->sig_bit);
1129 #else
1130 png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
1131 #endif
1132
1133 /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
1134 if ((transforms & PNG_TRANSFORM_BGR) != 0)
1135 #ifdef PNG_READ_BGR_SUPPORTED
1136 png_set_bgr(png_ptr);
1137 #else
1138 png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported");
1139 #endif
1140
1141 /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
1142 if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0)
1143 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
1144 png_set_swap_alpha(png_ptr);
1145 #else
1146 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported");
1147 #endif
1148
1149 /* Swap bytes of 16-bit files to least significant byte first */
1150 if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0)
1151 #ifdef PNG_READ_SWAP_SUPPORTED
1152 png_set_swap(png_ptr);
1153 #else
1154 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
1155 #endif
1156
1157 /* Added at libpng-1.2.41 */
1158 /* Invert the alpha channel from opacity to transparency */
1159 if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0)
1160 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1161 png_set_invert_alpha(png_ptr);
1162 #else
1163 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported");
1164 #endif
1165
1166 /* Added at libpng-1.2.41 */
1167 /* Expand grayscale image to RGB */
1168 if ((transforms & PNG_TRANSFORM_GRAY_TO_RGB) != 0)
1169 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1170 png_set_gray_to_rgb(png_ptr);
1171 #else
1172 png_app_error(png_ptr, "PNG_TRANSFORM_GRAY_TO_RGB not supported");
1173 #endif
1174
1175 /* Added at libpng-1.5.4 */
1176 if ((transforms & PNG_TRANSFORM_EXPAND_16) != 0)
1177 #ifdef PNG_READ_EXPAND_16_SUPPORTED
1178 png_set_expand_16(png_ptr);
1179 #else
1180 png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND_16 not supported");
1181 #endif
1182
1183 /* We don't handle adding filler bytes */
1184
1185 /* We use png_read_image and rely on that for interlace handling, but we also
1186 * call png_read_update_info therefore must turn on interlace handling now:
1187 */
1188 (void)png_set_interlace_handling(png_ptr);
1189
1190 /* Optional call to gamma correct and add the background to the palette
1191 * and update info structure. REQUIRED if you are expecting libpng to
1192 * update the palette for you (i.e., you selected such a transform above).
1193 */
1194 png_read_update_info(png_ptr, info_ptr);
1195
1196 /* -------------- image transformations end here ------------------- */
1197
1198 png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);
1199 if (info_ptr->row_pointers == NULL)
1200 {
1201 png_uint_32 iptr;
1202
1203 info_ptr->row_pointers = png_voidcast(png_bytepp, png_malloc(png_ptr,
1204 info_ptr->height * (sizeof (png_bytep))));
1205
1206 for (iptr=0; iptr<info_ptr->height; iptr++)
1207 info_ptr->row_pointers[iptr] = NULL;
1208
1209 info_ptr->free_me |= PNG_FREE_ROWS;
1210
1211 for (iptr = 0; iptr < info_ptr->height; iptr++)
1212 info_ptr->row_pointers[iptr] = png_voidcast(png_bytep,
1213 png_malloc(png_ptr, info_ptr->rowbytes));
1214 }
1215
1216 png_read_image(png_ptr, info_ptr->row_pointers);
1217 info_ptr->valid |= PNG_INFO_IDAT;
1218
1219 /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
1220 png_read_end(png_ptr, info_ptr);
1221
1222 PNG_UNUSED(params)
1223 }
1224 #endif /* INFO_IMAGE */
1225 #endif /* SEQUENTIAL_READ */
1226
1227 #ifdef PNG_SIMPLIFIED_READ_SUPPORTED
1228 /* SIMPLIFIED READ
1229 *
1230 * This code currently relies on the sequential reader, though it could easily
1231 * be made to work with the progressive one.
1232 */
1233 /* Arguments to png_image_finish_read: */
1234
1235 /* Encoding of PNG data (used by the color-map code) */
1236 # define P_NOTSET 0 /* File encoding not yet known */
1237 # define P_sRGB 1 /* 8-bit encoded to sRGB gamma */
1238 # define P_LINEAR 2 /* 16-bit linear: not encoded, NOT pre-multiplied! */
1239 # define P_FILE 3 /* 8-bit encoded to file gamma, not sRGB or linear */
1240 # define P_LINEAR8 4 /* 8-bit linear: only from a file value */
1241
1242 /* Color-map processing: after libpng has run on the PNG image further
1243 * processing may be needed to convert the data to color-map indices.
1244 */
1245 #define PNG_CMAP_NONE 0
1246 #define PNG_CMAP_GA 1 /* Process GA data to a color-map with alpha */
1247 #define PNG_CMAP_TRANS 2 /* Process GA data to a background index */
1248 #define PNG_CMAP_RGB 3 /* Process RGB data */
1249 #define PNG_CMAP_RGB_ALPHA 4 /* Process RGBA data */
1250
1251 /* The following document where the background is for each processing case. */
1252 #define PNG_CMAP_NONE_BACKGROUND 256
1253 #define PNG_CMAP_GA_BACKGROUND 231
1254 #define PNG_CMAP_TRANS_BACKGROUND 254
1255 #define PNG_CMAP_RGB_BACKGROUND 256
1256 #define PNG_CMAP_RGB_ALPHA_BACKGROUND 216
1257
1258 typedef struct
1259 {
1260 /* Arguments: */
1261 png_imagep image;
1262 png_voidp buffer;
1263 png_int_32 row_stride;
1264 png_voidp colormap;
1265 png_const_colorp background;
1266 /* Local variables: */
1267 png_voidp local_row;
1268 png_voidp first_row;
1269 ptrdiff_t row_bytes; /* step between rows */
1270 int file_encoding; /* E_ values above */
1271 png_fixed_point gamma_to_linear; /* For P_FILE, reciprocal of gamma */
1272 int colormap_processing; /* PNG_CMAP_ values above */
1273 } png_image_read_control;
1274
1275 /* Do all the *safe* initialization - 'safe' means that png_error won't be
1276 * called, so setting up the jmp_buf is not required. This means that anything
1277 * called from here must *not* call png_malloc - it has to call png_malloc_warn
1278 * instead so that control is returned safely back to this routine.
1279 */
1280 static int
1281 png_image_read_init(png_imagep image)
1282 {
1283 if (image->opaque == NULL)
1284 {
1285 png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, image,
1286 png_safe_error, png_safe_warning);
1287
1288 /* And set the rest of the structure to NULL to ensure that the various
1289 * fields are consistent.
1290 */
1291 memset(image, 0, (sizeof *image));
1292 image->version = PNG_IMAGE_VERSION;
1293
1294 if (png_ptr != NULL)
1295 {
1296 png_infop info_ptr = png_create_info_struct(png_ptr);
1297
1298 if (info_ptr != NULL)
1299 {
1300 png_controlp control = png_voidcast(png_controlp,
1301 png_malloc_warn(png_ptr, (sizeof *control)));
1302
1303 if (control != NULL)
1304 {
1305 memset(control, 0, (sizeof *control));
1306
1307 control->png_ptr = png_ptr;
1308 control->info_ptr = info_ptr;
1309 control->for_write = 0;
1310
1311 image->opaque = control;
1312 return 1;
1313 }
1314
1315 /* Error clean up */
1316 png_destroy_info_struct(png_ptr, &info_ptr);
1317 }
1318
1319 png_destroy_read_struct(&png_ptr, NULL, NULL);
1320 }
1321
1322 return png_image_error(image, "png_image_read: out of memory");
1323 }
1324
1325 return png_image_error(image, "png_image_read: opaque pointer not NULL");
1326 }
1327
1328 /* Utility to find the base format of a PNG file from a png_struct. */
1329 static png_uint_32
1330 png_image_format(png_structrp png_ptr)
1331 {
1332 png_uint_32 format = 0;
1333
1334 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
1335 format |= PNG_FORMAT_FLAG_COLOR;
1336
1337 if ((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
1338 format |= PNG_FORMAT_FLAG_ALPHA;
1339
1340 /* Use png_ptr here, not info_ptr, because by examination png_handle_tRNS
1341 * sets the png_struct fields; that's all we are interested in here. The
1342 * precise interaction with an app call to png_set_tRNS and PNG file reading
1343 * is unclear.
1344 */
1345 else if (png_ptr->num_trans > 0)
1346 format |= PNG_FORMAT_FLAG_ALPHA;
1347
1348 if (png_ptr->bit_depth == 16)
1349 format |= PNG_FORMAT_FLAG_LINEAR;
1350
1351 if ((png_ptr->color_type & PNG_COLOR_MASK_PALETTE) != 0)
1352 format |= PNG_FORMAT_FLAG_COLORMAP;
1353
1354 return format;
1355 }
1356
1357 /* Is the given gamma significantly different from sRGB? The test is the same
1358 * one used in pngrtran.c when deciding whether to do gamma correction. The
1359 * arithmetic optimizes the division by using the fact that the inverse of the
1360 * file sRGB gamma is 2.2
1361 */
1362 static int
1363 png_gamma_not_sRGB(png_fixed_point g)
1364 {
1365 if (g < PNG_FP_1)
1366 {
1367 /* An uninitialized gamma is assumed to be sRGB for the simplified API. */
1368 if (g == 0)
1369 return 0;
1370
1371 return png_gamma_significant((g * 11 + 2)/5 /* i.e. *2.2, rounded */);
1372 }
1373
1374 return 1;
1375 }
1376
1377 /* Do the main body of a 'png_image_begin_read' function; read the PNG file
1378 * header and fill in all the information. This is executed in a safe context,
1379 * unlike the init routine above.
1380 */
1381 static int
1382 png_image_read_header(png_voidp argument)
1383 {
1384 png_imagep image = png_voidcast(png_imagep, argument);
1385 png_structrp png_ptr = image->opaque->png_ptr;
1386 png_inforp info_ptr = image->opaque->info_ptr;
1387
1388 png_set_benign_errors(png_ptr, 1/*warn*/);
1389 png_read_info(png_ptr, info_ptr);
1390
1391 /* Do this the fast way; just read directly out of png_struct. */
1392 image->width = png_ptr->width;
1393 image->height = png_ptr->height;
1394
1395 {
1396 png_uint_32 format = png_image_format(png_ptr);
1397
1398 image->format = format;
1399
1400 #ifdef PNG_COLORSPACE_SUPPORTED
1401 /* Does the colorspace match sRGB? If there is no color endpoint
1402 * (colorant) information assume yes, otherwise require the
1403 * 'ENDPOINTS_MATCHP_sRGB' colorspace flag to have been set. If the
1404 * colorspace has been determined to be invalid ignore it.
1405 */
1406 if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && ((png_ptr->colorspace.flags
1407 & (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB|
1408 PNG_COLORSPACE_INVALID)) == PNG_COLORSPACE_HAVE_ENDPOINTS))
1409 image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB;
1410 #endif
1411 }
1412
1413 /* We need the maximum number of entries regardless of the format the
1414 * application sets here.
1415 */
1416 {
1417 png_uint_32 cmap_entries;
1418
1419 switch (png_ptr->color_type)
1420 {
1421 case PNG_COLOR_TYPE_GRAY:
1422 cmap_entries = 1U << png_ptr->bit_depth;
1423 break;
1424
1425 case PNG_COLOR_TYPE_PALETTE:
1426 cmap_entries = png_ptr->num_palette;
1427 break;
1428
1429 default:
1430 cmap_entries = 256;
1431 break;
1432 }
1433
1434 if (cmap_entries > 256)
1435 cmap_entries = 256;
1436
1437 image->colormap_entries = cmap_entries;
1438 }
1439
1440 return 1;
1441 }
1442
1443 #ifdef PNG_STDIO_SUPPORTED
1444 int PNGAPI
1445 png_image_begin_read_from_stdio(png_imagep image, FILE* file)
1446 {
1447 if (image != NULL && image->version == PNG_IMAGE_VERSION)
1448 {
1449 if (file != NULL)
1450 {
1451 if (png_image_read_init(image) != 0)
1452 {
1453 /* This is slightly evil, but png_init_io doesn't do anything other
1454 * than this and we haven't changed the standard IO functions so
1455 * this saves a 'safe' function.
1456 */
1457 image->opaque->png_ptr->io_ptr = file;
1458 return png_safe_execute(image, png_image_read_header, image);
1459 }
1460 }
1461
1462 else
1463 return png_image_error(image,
1464 "png_image_begin_read_from_stdio: invalid argument");
1465 }
1466
1467 else if (image != NULL)
1468 return png_image_error(image,
1469 "png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION");
1470
1471 return 0;
1472 }
1473
1474 int PNGAPI
1475 png_image_begin_read_from_file(png_imagep image, const char *file_name)
1476 {
1477 if (image != NULL && image->version == PNG_IMAGE_VERSION)
1478 {
1479 if (file_name != NULL)
1480 {
1481 FILE *fp = fopen(file_name, "rb");
1482
1483 if (fp != NULL)
1484 {
1485 if (png_image_read_init(image) != 0)
1486 {
1487 image->opaque->png_ptr->io_ptr = fp;
1488 image->opaque->owned_file = 1;
1489 return png_safe_execute(image, png_image_read_header, image);
1490 }
1491
1492 /* Clean up: just the opened file. */
1493 (void)fclose(fp);
1494 }
1495
1496 else
1497 return png_image_error(image, strerror(errno));
1498 }
1499
1500 else
1501 return png_image_error(image,
1502 "png_image_begin_read_from_file: invalid argument");
1503 }
1504
1505 else if (image != NULL)
1506 return png_image_error(image,
1507 "png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION");
1508
1509 return 0;
1510 }
1511 #endif /* STDIO */
1512
1513 static void PNGCBAPI
1514 png_image_memory_read(png_structp png_ptr, png_bytep out, png_size_t need)
1515 {
1516 if (png_ptr != NULL)
1517 {
1518 png_imagep image = png_voidcast(png_imagep, png_ptr->io_ptr);
1519 if (image != NULL)
1520 {
1521 png_controlp cp = image->opaque;
1522 if (cp != NULL)
1523 {
1524 png_const_bytep memory = cp->memory;
1525 png_size_t size = cp->size;
1526
1527 if (memory != NULL && size >= need)
1528 {
1529 memcpy(out, memory, need);
1530 cp->memory = memory + need;
1531 cp->size = size - need;
1532 return;
1533 }
1534
1535 png_error(png_ptr, "read beyond end of data");
1536 }
1537 }
1538
1539 png_error(png_ptr, "invalid memory read");
1540 }
1541 }
1542
1543 int PNGAPI png_image_begin_read_from_memory(png_imagep image,
1544 png_const_voidp memory, png_size_t size)
1545 {
1546 if (image != NULL && image->version == PNG_IMAGE_VERSION)
1547 {
1548 if (memory != NULL && size > 0)
1549 {
1550 if (png_image_read_init(image) != 0)
1551 {
1552 /* Now set the IO functions to read from the memory buffer and
1553 * store it into io_ptr. Again do this in-place to avoid calling a
1554 * libpng function that requires error handling.
1555 */
1556 image->opaque->memory = png_voidcast(png_const_bytep, memory);
1557 image->opaque->size = size;
1558 image->opaque->png_ptr->io_ptr = image;
1559 image->opaque->png_ptr->read_data_fn = png_image_memory_read;
1560
1561 return png_safe_execute(image, png_image_read_header, image);
1562 }
1563 }
1564
1565 else
1566 return png_image_error(image,
1567 "png_image_begin_read_from_memory: invalid argument");
1568 }
1569
1570 else if (image != NULL)
1571 return png_image_error(image,
1572 "png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION");
1573
1574 return 0;
1575 }
1576
1577 /* Utility function to skip chunks that are not used by the simplified image
1578 * read functions and an appropriate macro to call it.
1579 */
1580 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
1581 static void
1582 png_image_skip_unused_chunks(png_structrp png_ptr)
1583 {
1584 /* Prepare the reader to ignore all recognized chunks whose data will not
1585 * be used, i.e., all chunks recognized by libpng except for those
1586 * involved in basic image reading:
1587 *
1588 * IHDR, PLTE, IDAT, IEND
1589 *
1590 * Or image data handling:
1591 *
1592 * tRNS, bKGD, gAMA, cHRM, sRGB, [iCCP] and sBIT.
1593 *
1594 * This provides a small performance improvement and eliminates any
1595 * potential vulnerability to security problems in the unused chunks.
1596 *
1597 * At present the iCCP chunk data isn't used, so iCCP chunk can be ignored
1598 * too. This allows the simplified API to be compiled without iCCP support,
1599 * however if the support is there the chunk is still checked to detect
1600 * errors (which are unfortunately quite common.)
1601 */
1602 {
1603 static PNG_CONST png_byte chunks_to_process[] = {
1604 98, 75, 71, 68, '\0', /* bKGD */
1605 99, 72, 82, 77, '\0', /* cHRM */
1606 103, 65, 77, 65, '\0', /* gAMA */
1607 # ifdef PNG_READ_iCCP_SUPPORTED
1608 105, 67, 67, 80, '\0', /* iCCP */
1609 # endif
1610 115, 66, 73, 84, '\0', /* sBIT */
1611 115, 82, 71, 66, '\0', /* sRGB */
1612 };
1613
1614 /* Ignore unknown chunks and all other chunks except for the
1615 * IHDR, PLTE, tRNS, IDAT, and IEND chunks.
1616 */
1617 png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_NEVER,
1618 NULL, -1);
1619
1620 /* But do not ignore image data handling chunks */
1621 png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_AS_DEFAULT,
1622 chunks_to_process, (int)/*SAFE*/(sizeof chunks_to_process)/5);
1623 }
1624 }
1625
1626 # define PNG_SKIP_CHUNKS(p) png_image_skip_unused_chunks(p)
1627 #else
1628 # define PNG_SKIP_CHUNKS(p) ((void)0)
1629 #endif /* HANDLE_AS_UNKNOWN */
1630
1631 /* The following macro gives the exact rounded answer for all values in the
1632 * range 0..255 (it actually divides by 51.2, but the rounding still generates
1633 * the correct numbers 0..5
1634 */
1635 #define PNG_DIV51(v8) (((v8) * 5 + 130) >> 8)
1636
1637 /* Utility functions to make particular color-maps */
1638 static void
1639 set_file_encoding(png_image_read_control *display)
1640 {
1641 png_fixed_point g = display->image->opaque->png_ptr->colorspace.gamma;
1642 if (png_gamma_significant(g) != 0)
1643 {
1644 if (png_gamma_not_sRGB(g) != 0)
1645 {
1646 display->file_encoding = P_FILE;
1647 display->gamma_to_linear = png_reciprocal(g);
1648 }
1649
1650 else
1651 display->file_encoding = P_sRGB;
1652 }
1653
1654 else
1655 display->file_encoding = P_LINEAR8;
1656 }
1657
1658 static unsigned int
1659 decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding)
1660 {
1661 if (encoding == P_FILE) /* double check */
1662 encoding = display->file_encoding;
1663
1664 if (encoding == P_NOTSET) /* must be the file encoding */
1665 {
1666 set_file_encoding(display);
1667 encoding = display->file_encoding;
1668 }
1669
1670 switch (encoding)
1671 {
1672 case P_FILE:
1673 value = png_gamma_16bit_correct(value*257, display->gamma_to_linear);
1674 break;
1675
1676 case P_sRGB:
1677 value = png_sRGB_table[value];
1678 break;
1679
1680 case P_LINEAR:
1681 break;
1682
1683 case P_LINEAR8:
1684 value *= 257;
1685 break;
1686
1687 default:
1688 png_error(display->image->opaque->png_ptr,
1689 "unexpected encoding (internal error)");
1690 break;
1691 }
1692
1693 return value;
1694 }
1695
1696 static png_uint_32
1697 png_colormap_compose(png_image_read_control *display,
1698 png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha,
1699 png_uint_32 background, int encoding)
1700 {
1701 /* The file value is composed on the background, the background has the given
1702 * encoding and so does the result, the file is encoded with P_FILE and the
1703 * file and alpha are 8-bit values. The (output) encoding will always be
1704 * P_LINEAR or P_sRGB.
1705 */
1706 png_uint_32 f = decode_gamma(display, foreground, foreground_encoding);
1707 png_uint_32 b = decode_gamma(display, background, encoding);
1708
1709 /* The alpha is always an 8-bit value (it comes from the palette), the value
1710 * scaled by 255 is what PNG_sRGB_FROM_LINEAR requires.
1711 */
1712 f = f * alpha + b * (255-alpha);
1713
1714 if (encoding == P_LINEAR)
1715 {
1716 /* Scale to 65535; divide by 255, approximately (in fact this is extremely
1717 * accurate, it divides by 255.00000005937181414556, with no overflow.)
1718 */
1719 f *= 257; /* Now scaled by 65535 */
1720 f += f >> 16;
1721 f = (f+32768) >> 16;
1722 }
1723
1724 else /* P_sRGB */
1725 f = PNG_sRGB_FROM_LINEAR(f);
1726
1727 return f;
1728 }
1729
1730 /* NOTE: P_LINEAR values to this routine must be 16-bit, but P_FILE values must
1731 * be 8-bit.
1732 */
1733 static void
1734 png_create_colormap_entry(png_image_read_control *display,
1735 png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue,
1736 png_uint_32 alpha, int encoding)
1737 {
1738 png_imagep image = display->image;
1739 const int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
1740 P_LINEAR : P_sRGB;
1741 const int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 &&
1742 (red != green || green != blue);
1743
1744 if (ip > 255)
1745 png_error(image->opaque->png_ptr, "color-map index out of range");
1746
1747 /* Update the cache with whether the file gamma is significantly different
1748 * from sRGB.
1749 */
1750 if (encoding == P_FILE)
1751 {
1752 if (display->file_encoding == P_NOTSET)
1753 set_file_encoding(display);
1754
1755 /* Note that the cached value may be P_FILE too, but if it is then the
1756 * gamma_to_linear member has been set.
1757 */
1758 encoding = display->file_encoding;
1759 }
1760
1761 if (encoding == P_FILE)
1762 {
1763 png_fixed_point g = display->gamma_to_linear;
1764
1765 red = png_gamma_16bit_correct(red*257, g);
1766 green = png_gamma_16bit_correct(green*257, g);
1767 blue = png_gamma_16bit_correct(blue*257, g);
1768
1769 if (convert_to_Y != 0 || output_encoding == P_LINEAR)
1770 {
1771 alpha *= 257;
1772 encoding = P_LINEAR;
1773 }
1774
1775 else
1776 {
1777 red = PNG_sRGB_FROM_LINEAR(red * 255);
1778 green = PNG_sRGB_FROM_LINEAR(green * 255);
1779 blue = PNG_sRGB_FROM_LINEAR(blue * 255);
1780 encoding = P_sRGB;
1781 }
1782 }
1783
1784 else if (encoding == P_LINEAR8)
1785 {
1786 /* This encoding occurs quite frequently in test cases because PngSuite
1787 * includes a gAMA 1.0 chunk with most images.
1788 */
1789 red *= 257;
1790 green *= 257;
1791 blue *= 257;
1792 alpha *= 257;
1793 encoding = P_LINEAR;
1794 }
1795
1796 else if (encoding == P_sRGB &&
1797 (convert_to_Y != 0 || output_encoding == P_LINEAR))
1798 {
1799 /* The values are 8-bit sRGB values, but must be converted to 16-bit
1800 * linear.
1801 */
1802 red = png_sRGB_table[red];
1803 green = png_sRGB_table[green];
1804 blue = png_sRGB_table[blue];
1805 alpha *= 257;
1806 encoding = P_LINEAR;
1807 }
1808
1809 /* This is set if the color isn't gray but the output is. */
1810 if (encoding == P_LINEAR)
1811 {
1812 if (convert_to_Y != 0)
1813 {
1814 /* NOTE: these values are copied from png_do_rgb_to_gray */
1815 png_uint_32 y = (png_uint_32)6968 * red + (png_uint_32)23434 * green +
1816 (png_uint_32)2366 * blue;
1817
1818 if (output_encoding == P_LINEAR)
1819 y = (y + 16384) >> 15;
1820
1821 else
1822 {
1823 /* y is scaled by 32768, we need it scaled by 255: */
1824 y = (y + 128) >> 8;
1825 y *= 255;
1826 y = PNG_sRGB_FROM_LINEAR((y + 64) >> 7);
1827 encoding = P_sRGB;
1828 }
1829
1830 blue = red = green = y;
1831 }
1832
1833 else if (output_encoding == P_sRGB)
1834 {
1835 red = PNG_sRGB_FROM_LINEAR(red * 255);
1836 green = PNG_sRGB_FROM_LINEAR(green * 255);
1837 blue = PNG_sRGB_FROM_LINEAR(blue * 255);
1838 alpha = PNG_DIV257(alpha);
1839 encoding = P_sRGB;
1840 }
1841 }
1842
1843 if (encoding != output_encoding)
1844 png_error(image->opaque->png_ptr, "bad encoding (internal error)");
1845
1846 /* Store the value. */
1847 {
1848 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
1849 const int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
1850 (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
1851 # else
1852 # define afirst 0
1853 # endif
1854 # ifdef PNG_FORMAT_BGR_SUPPORTED
1855 const int bgr = (image->format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
1856 # else
1857 # define bgr 0
1858 # endif
1859
1860 if (output_encoding == P_LINEAR)
1861 {
1862 png_uint_16p entry = png_voidcast(png_uint_16p, display->colormap);
1863
1864 entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
1865
1866 /* The linear 16-bit values must be pre-multiplied by the alpha channel
1867 * value, if less than 65535 (this is, effectively, composite on black
1868 * if the alpha channel is removed.)
1869 */
1870 switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
1871 {
1872 case 4:
1873 entry[afirst ? 0 : 3] = (png_uint_16)alpha;
1874 /* FALL THROUGH */
1875
1876 case 3:
1877 if (alpha < 65535)
1878 {
1879 if (alpha > 0)
1880 {
1881 blue = (blue * alpha + 32767U)/65535U;
1882 green = (green * alpha + 32767U)/65535U;
1883 red = (red * alpha + 32767U)/65535U;
1884 }
1885
1886 else
1887 red = green = blue = 0;
1888 }
1889 entry[afirst + (2 ^ bgr)] = (png_uint_16)blue;
1890 entry[afirst + 1] = (png_uint_16)green;
1891 entry[afirst + bgr] = (png_uint_16)red;
1892 break;
1893
1894 case 2:
1895 entry[1 ^ afirst] = (png_uint_16)alpha;
1896 /* FALL THROUGH */
1897
1898 case 1:
1899 if (alpha < 65535)
1900 {
1901 if (alpha > 0)
1902 green = (green * alpha + 32767U)/65535U;
1903
1904 else
1905 green = 0;
1906 }
1907 entry[afirst] = (png_uint_16)green;
1908 break;
1909
1910 default:
1911 break;
1912 }
1913 }
1914
1915 else /* output encoding is P_sRGB */
1916 {
1917 png_bytep entry = png_voidcast(png_bytep, display->colormap);
1918
1919 entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
1920
1921 switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
1922 {
1923 case 4:
1924 entry[afirst ? 0 : 3] = (png_byte)alpha;
1925 case 3:
1926 entry[afirst + (2 ^ bgr)] = (png_byte)blue;
1927 entry[afirst + 1] = (png_byte)green;
1928 entry[afirst + bgr] = (png_byte)red;
1929 break;
1930
1931 case 2:
1932 entry[1 ^ afirst] = (png_byte)alpha;
1933 case 1:
1934 entry[afirst] = (png_byte)green;
1935 break;
1936
1937 default:
1938 break;
1939 }
1940 }
1941
1942 # ifdef afirst
1943 # undef afirst
1944 # endif
1945 # ifdef bgr
1946 # undef bgr
1947 # endif
1948 }
1949 }
1950
1951 static int
1952 make_gray_file_colormap(png_image_read_control *display)
1953 {
1954 unsigned int i;
1955
1956 for (i=0; i<256; ++i)
1957 png_create_colormap_entry(display, i, i, i, i, 255, P_FILE);
1958
1959 return i;
1960 }
1961
1962 static int
1963 make_gray_colormap(png_image_read_control *display)
1964 {
1965 unsigned int i;
1966
1967 for (i=0; i<256; ++i)
1968 png_create_colormap_entry(display, i, i, i, i, 255, P_sRGB);
1969
1970 return i;
1971 }
1972 #define PNG_GRAY_COLORMAP_ENTRIES 256
1973
1974 static int
1975 make_ga_colormap(png_image_read_control *display)
1976 {
1977 unsigned int i, a;
1978
1979 /* Alpha is retained, the output will be a color-map with entries
1980 * selected by six levels of alpha. One transparent entry, 6 gray
1981 * levels for all the intermediate alpha values, leaving 230 entries
1982 * for the opaque grays. The color-map entries are the six values
1983 * [0..5]*51, the GA processing uses PNG_DIV51(value) to find the
1984 * relevant entry.
1985 *
1986 * if (alpha > 229) // opaque
1987 * {
1988 * // The 231 entries are selected to make the math below work:
1989 * base = 0;
1990 * entry = (231 * gray + 128) >> 8;
1991 * }
1992 * else if (alpha < 26) // transparent
1993 * {
1994 * base = 231;
1995 * entry = 0;
1996 * }
1997 * else // partially opaque
1998 * {
1999 * base = 226 + 6 * PNG_DIV51(alpha);
2000 * entry = PNG_DIV51(gray);
2001 * }
2002 */
2003 i = 0;
2004 while (i < 231)
2005 {
2006 unsigned int gray = (i * 256 + 115) / 231;
2007 png_create_colormap_entry(display, i++, gray, gray, gray, 255, P_sRGB);
2008 }
2009
2010 /* 255 is used here for the component values for consistency with the code
2011 * that undoes premultiplication in pngwrite.c.
2012 */
2013 png_create_colormap_entry(display, i++, 255, 255, 255, 0, P_sRGB);
2014
2015 for (a=1; a<5; ++a)
2016 {
2017 unsigned int g;
2018
2019 for (g=0; g<6; ++g)
2020 png_create_colormap_entry(display, i++, g*51, g*51, g*51, a*51,
2021 P_sRGB);
2022 }
2023
2024 return i;
2025 }
2026
2027 #define PNG_GA_COLORMAP_ENTRIES 256
2028
2029 static int
2030 make_rgb_colormap(png_image_read_control *display)
2031 {
2032 unsigned int i, r;
2033
2034 /* Build a 6x6x6 opaque RGB cube */
2035 for (i=r=0; r<6; ++r)
2036 {
2037 unsigned int g;
2038
2039 for (g=0; g<6; ++g)
2040 {
2041 unsigned int b;
2042
2043 for (b=0; b<6; ++b)
2044 png_create_colormap_entry(display, i++, r*51, g*51, b*51, 255,
2045 P_sRGB);
2046 }
2047 }
2048
2049 return i;
2050 }
2051
2052 #define PNG_RGB_COLORMAP_ENTRIES 216
2053
2054 /* Return a palette index to the above palette given three 8-bit sRGB values. */
2055 #define PNG_RGB_INDEX(r,g,b) \
2056 ((png_byte)(6 * (6 * PNG_DIV51(r) + PNG_DIV51(g)) + PNG_DIV51(b)))
2057
2058 static int
2059 png_image_read_colormap(png_voidp argument)
2060 {
2061 png_image_read_control *display =
2062 png_voidcast(png_image_read_control*, argument);
2063 const png_imagep image = display->image;
2064
2065 const png_structrp png_ptr = image->opaque->png_ptr;
2066 const png_uint_32 output_format = image->format;
2067 const int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
2068 P_LINEAR : P_sRGB;
2069
2070 unsigned int cmap_entries;
2071 unsigned int output_processing; /* Output processing option */
2072 unsigned int data_encoding = P_NOTSET; /* Encoding libpng must produce */
2073
2074 /* Background information; the background color and the index of this color
2075 * in the color-map if it exists (else 256).
2076 */
2077 unsigned int background_index = 256;
2078 png_uint_32 back_r, back_g, back_b;
2079
2080 /* Flags to accumulate things that need to be done to the input. */
2081 int expand_tRNS = 0;
2082
2083 /* Exclude the NYI feature of compositing onto a color-mapped buffer; it is
2084 * very difficult to do, the results look awful, and it is difficult to see
2085 * what possible use it is because the application can't control the
2086 * color-map.
2087 */
2088 if (((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0 ||
2089 png_ptr->num_trans > 0) /* alpha in input */ &&
2090 ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) /* no alpha in output */)
2091 {
2092 if (output_encoding == P_LINEAR) /* compose on black */
2093 back_b = back_g = back_r = 0;
2094
2095 else if (display->background == NULL /* no way to remove it */)
2096 png_error(png_ptr,
2097 "a background color must be supplied to remove alpha/transparency");
2098
2099 /* Get a copy of the background color (this avoids repeating the checks
2100 * below.) The encoding is 8-bit sRGB or 16-bit linear, depending on the
2101 * output format.
2102 */
2103 else
2104 {
2105 back_g = display->background->green;
2106 if ((output_format & PNG_FORMAT_FLAG_COLOR) != 0)
2107 {
2108 back_r = display->background->red;
2109 back_b = display->background->blue;
2110 }
2111 else
2112 back_b = back_r = back_g;
2113 }
2114 }
2115
2116 else if (output_encoding == P_LINEAR)
2117 back_b = back_r = back_g = 65535;
2118
2119 else
2120 back_b = back_r = back_g = 255;
2121
2122 /* Default the input file gamma if required - this is necessary because
2123 * libpng assumes that if no gamma information is present the data is in the
2124 * output format, but the simplified API deduces the gamma from the input
2125 * format.
2126 */
2127 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) == 0)
2128 {
2129 /* Do this directly, not using the png_colorspace functions, to ensure
2130 * that it happens even if the colorspace is invalid (though probably if
2131 * it is the setting will be ignored) Note that the same thing can be
2132 * achieved at the application interface with png_set_gAMA.
2133 */
2134 if (png_ptr->bit_depth == 16 &&
2135 (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
2136 png_ptr->colorspace.gamma = PNG_GAMMA_LINEAR;
2137
2138 else
2139 png_ptr->colorspace.gamma = PNG_GAMMA_sRGB_INVERSE;
2140
2141 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
2142 }
2143
2144 /* Decide what to do based on the PNG color type of the input data. The
2145 * utility function png_create_colormap_entry deals with most aspects of the
2146 * output transformations; this code works out how to produce bytes of
2147 * color-map entries from the original format.
2148 */
2149 switch (png_ptr->color_type)
2150 {
2151 case PNG_COLOR_TYPE_GRAY:
2152 if (png_ptr->bit_depth <= 8)
2153 {
2154 /* There at most 256 colors in the output, regardless of
2155 * transparency.
2156 */
2157 unsigned int step, i, val, trans = 256/*ignore*/, back_alpha = 0;
2158
2159 cmap_entries = 1U << png_ptr->bit_depth;
2160 if (cmap_entries > image->colormap_entries)
2161 png_error(png_ptr, "gray[8] color-map: too few entries");
2162
2163 step = 255 / (cmap_entries - 1);
2164 output_processing = PNG_CMAP_NONE;
2165
2166 /* If there is a tRNS chunk then this either selects a transparent
2167 * value or, if the output has no alpha, the background color.
2168 */
2169 if (png_ptr->num_trans > 0)
2170 {
2171 trans = png_ptr->trans_color.gray;
2172
2173 if ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0)
2174 back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
2175 }
2176
2177 /* png_create_colormap_entry just takes an RGBA and writes the
2178 * corresponding color-map entry using the format from 'image',
2179 * including the required conversion to sRGB or linear as
2180 * appropriate. The input values are always either sRGB (if the
2181 * gamma correction flag is 0) or 0..255 scaled file encoded values
2182 * (if the function must gamma correct them).
2183 */
2184 for (i=val=0; i<cmap_entries; ++i, val += step)
2185 {
2186 /* 'i' is a file value. While this will result in duplicated
2187 * entries for 8-bit non-sRGB encoded files it is necessary to
2188 * have non-gamma corrected values to do tRNS handling.
2189 */
2190 if (i != trans)
2191 png_create_colormap_entry(display, i, val, val, val, 255,
2192 P_FILE/*8-bit with file gamma*/);
2193
2194 /* Else this entry is transparent. The colors don't matter if
2195 * there is an alpha channel (back_alpha == 0), but it does no
2196 * harm to pass them in; the values are not set above so this
2197 * passes in white.
2198 *
2199 * NOTE: this preserves the full precision of the application
2200 * supplied background color when it is used.
2201 */
2202 else
2203 png_create_colormap_entry(display, i, back_r, back_g, back_b,
2204 back_alpha, output_encoding);
2205 }
2206
2207 /* We need libpng to preserve the original encoding. */
2208 data_encoding = P_FILE;
2209
2210 /* The rows from libpng, while technically gray values, are now also
2211 * color-map indices; however, they may need to be expanded to 1
2212 * byte per pixel. This is what png_set_packing does (i.e., it
2213 * unpacks the bit values into bytes.)
2214 */
2215 if (png_ptr->bit_depth < 8)
2216 png_set_packing(png_ptr);
2217 }
2218
2219 else /* bit depth is 16 */
2220 {
2221 /* The 16-bit input values can be converted directly to 8-bit gamma
2222 * encoded values; however, if a tRNS chunk is present 257 color-map
2223 * entries are required. This means that the extra entry requires
2224 * special processing; add an alpha channel, sacrifice gray level
2225 * 254 and convert transparent (alpha==0) entries to that.
2226 *
2227 * Use libpng to chop the data to 8 bits. Convert it to sRGB at the
2228 * same time to minimize quality loss. If a tRNS chunk is present
2229 * this means libpng must handle it too; otherwise it is impossible
2230 * to do the exact match on the 16-bit value.
2231 *
2232 * If the output has no alpha channel *and* the background color is
2233 * gray then it is possible to let libpng handle the substitution by
2234 * ensuring that the corresponding gray level matches the background
2235 * color exactly.
2236 */
2237 data_encoding = P_sRGB;
2238
2239 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2240 png_error(png_ptr, "gray[16] color-map: too few entries");
2241
2242 cmap_entries = make_gray_colormap(display);
2243
2244 if (png_ptr->num_trans > 0)
2245 {
2246 unsigned int back_alpha;
2247
2248 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2249 back_alpha = 0;
2250
2251 else
2252 {
2253 if (back_r == back_g && back_g == back_b)
2254 {
2255 /* Background is gray; no special processing will be
2256 * required.
2257 */
2258 png_color_16 c;
2259 png_uint_32 gray = back_g;
2260
2261 if (output_encoding == P_LINEAR)
2262 {
2263 gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2264
2265 /* And make sure the corresponding palette entry
2266 * matches.
2267 */
2268 png_create_colormap_entry(display, gray, back_g, back_g,
2269 back_g, 65535, P_LINEAR);
2270 }
2271
2272 /* The background passed to libpng, however, must be the
2273 * sRGB value.
2274 */
2275 c.index = 0; /*unused*/
2276 c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2277
2278 /* NOTE: does this work without expanding tRNS to alpha?
2279 * It should be the color->gray case below apparently
2280 * doesn't.
2281 */
2282 png_set_background_fixed(png_ptr, &c,
2283 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2284 0/*gamma: not used*/);
2285
2286 output_processing = PNG_CMAP_NONE;
2287 break;
2288 }
2289
2290 back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
2291 }
2292
2293 /* output_processing means that the libpng-processed row will be
2294 * 8-bit GA and it has to be processing to single byte color-map
2295 * values. Entry 254 is replaced by either a completely
2296 * transparent entry or by the background color at full
2297 * precision (and the background color is not a simple gray
2298 * level in this case.)
2299 */
2300 expand_tRNS = 1;
2301 output_processing = PNG_CMAP_TRANS;
2302 background_index = 254;
2303
2304 /* And set (overwrite) color-map entry 254 to the actual
2305 * background color at full precision.
2306 */
2307 png_create_colormap_entry(display, 254, back_r, back_g, back_b,
2308 back_alpha, output_encoding);
2309 }
2310
2311 else
2312 output_processing = PNG_CMAP_NONE;
2313 }
2314 break;
2315
2316 case PNG_COLOR_TYPE_GRAY_ALPHA:
2317 /* 8-bit or 16-bit PNG with two channels - gray and alpha. A minimum
2318 * of 65536 combinations. If, however, the alpha channel is to be
2319 * removed there are only 256 possibilities if the background is gray.
2320 * (Otherwise there is a subset of the 65536 possibilities defined by
2321 * the triangle between black, white and the background color.)
2322 *
2323 * Reduce 16-bit files to 8-bit and sRGB encode the result. No need to
2324 * worry about tRNS matching - tRNS is ignored if there is an alpha
2325 * channel.
2326 */
2327 data_encoding = P_sRGB;
2328
2329 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2330 {
2331 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2332 png_error(png_ptr, "gray+alpha color-map: too few entries");
2333
2334 cmap_entries = make_ga_colormap(display);
2335
2336 background_index = PNG_CMAP_GA_BACKGROUND;
2337 output_processing = PNG_CMAP_GA;
2338 }
2339
2340 else /* alpha is removed */
2341 {
2342 /* Alpha must be removed as the PNG data is processed when the
2343 * background is a color because the G and A channels are
2344 * independent and the vector addition (non-parallel vectors) is a
2345 * 2-D problem.
2346 *
2347 * This can be reduced to the same algorithm as above by making a
2348 * colormap containing gray levels (for the opaque grays), a
2349 * background entry (for a transparent pixel) and a set of four six
2350 * level color values, one set for each intermediate alpha value.
2351 * See the comments in make_ga_colormap for how this works in the
2352 * per-pixel processing.
2353 *
2354 * If the background is gray, however, we only need a 256 entry gray
2355 * level color map. It is sufficient to make the entry generated
2356 * for the background color be exactly the color specified.
2357 */
2358 if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0 ||
2359 (back_r == back_g && back_g == back_b))
2360 {
2361 /* Background is gray; no special processing will be required. */
2362 png_color_16 c;
2363 png_uint_32 gray = back_g;
2364
2365 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2366 png_error(png_ptr, "gray-alpha color-map: too few entries");
2367
2368 cmap_entries = make_gray_colormap(display);
2369
2370 if (output_encoding == P_LINEAR)
2371 {
2372 gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2373
2374 /* And make sure the corresponding palette entry matches. */
2375 png_create_colormap_entry(display, gray, back_g, back_g,
2376 back_g, 65535, P_LINEAR);
2377 }
2378
2379 /* The background passed to libpng, however, must be the sRGB
2380 * value.
2381 */
2382 c.index = 0; /*unused*/
2383 c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2384
2385 png_set_background_fixed(png_ptr, &c,
2386 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2387 0/*gamma: not used*/);
2388
2389 output_processing = PNG_CMAP_NONE;
2390 }
2391
2392 else
2393 {
2394 png_uint_32 i, a;
2395
2396 /* This is the same as png_make_ga_colormap, above, except that
2397 * the entries are all opaque.
2398 */
2399 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2400 png_error(png_ptr, "ga-alpha color-map: too few entries");
2401
2402 i = 0;
2403 while (i < 231)
2404 {
2405 png_uint_32 gray = (i * 256 + 115) / 231;
2406 png_create_colormap_entry(display, i++, gray, gray, gray,
2407 255, P_sRGB);
2408 }
2409
2410 /* NOTE: this preserves the full precision of the application
2411 * background color.
2412 */
2413 background_index = i;
2414 png_create_colormap_entry(display, i++, back_r, back_g, back_b,
2415 output_encoding == P_LINEAR ? 65535U : 255U, output_encoding);
2416
2417 /* For non-opaque input composite on the sRGB background - this
2418 * requires inverting the encoding for each component. The input
2419 * is still converted to the sRGB encoding because this is a
2420 * reasonable approximate to the logarithmic curve of human
2421 * visual sensitivity, at least over the narrow range which PNG
2422 * represents. Consequently 'G' is always sRGB encoded, while
2423 * 'A' is linear. We need the linear background colors.
2424 */
2425 if (output_encoding == P_sRGB) /* else already linear */
2426 {
2427 /* This may produce a value not exactly matching the
2428 * background, but that's ok because these numbers are only
2429 * used when alpha != 0
2430 */
2431 back_r = png_sRGB_table[back_r];
2432 back_g = png_sRGB_table[back_g];
2433 back_b = png_sRGB_table[back_b];
2434 }
2435
2436 for (a=1; a<5; ++a)
2437 {
2438 unsigned int g;
2439
2440 /* PNG_sRGB_FROM_LINEAR expects a 16-bit linear value scaled
2441 * by an 8-bit alpha value (0..255).
2442 */
2443 png_uint_32 alpha = 51 * a;
2444 png_uint_32 back_rx = (255-alpha) * back_r;
2445 png_uint_32 back_gx = (255-alpha) * back_g;
2446 png_uint_32 back_bx = (255-alpha) * back_b;
2447
2448 for (g=0; g<6; ++g)
2449 {
2450 png_uint_32 gray = png_sRGB_table[g*51] * alpha;
2451
2452 png_create_colormap_entry(display, i++,
2453 PNG_sRGB_FROM_LINEAR(gray + back_rx),
2454 PNG_sRGB_FROM_LINEAR(gray + back_gx),
2455 PNG_sRGB_FROM_LINEAR(gray + back_bx), 255, P_sRGB);
2456 }
2457 }
2458
2459 cmap_entries = i;
2460 output_processing = PNG_CMAP_GA;
2461 }
2462 }
2463 break;
2464
2465 case PNG_COLOR_TYPE_RGB:
2466 case PNG_COLOR_TYPE_RGB_ALPHA:
2467 /* Exclude the case where the output is gray; we can always handle this
2468 * with the cases above.
2469 */
2470 if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0)
2471 {
2472 /* The color-map will be grayscale, so we may as well convert the
2473 * input RGB values to a simple grayscale and use the grayscale
2474 * code above.
2475 *
2476 * NOTE: calling this apparently damages the recognition of the
2477 * transparent color in background color handling; call
2478 * png_set_tRNS_to_alpha before png_set_background_fixed.
2479 */
2480 png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, -1,
2481 -1);
2482 data_encoding = P_sRGB;
2483
2484 /* The output will now be one or two 8-bit gray or gray+alpha
2485 * channels. The more complex case arises when the input has alpha.
2486 */
2487 if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2488 png_ptr->num_trans > 0) &&
2489 (output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2490 {
2491 /* Both input and output have an alpha channel, so no background
2492 * processing is required; just map the GA bytes to the right
2493 * color-map entry.
2494 */
2495 expand_tRNS = 1;
2496
2497 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2498 png_error(png_ptr, "rgb[ga] color-map: too few entries");
2499
2500 cmap_entries = make_ga_colormap(display);
2501 background_index = PNG_CMAP_GA_BACKGROUND;
2502 output_processing = PNG_CMAP_GA;
2503 }
2504
2505 else
2506 {
2507 /* Either the input or the output has no alpha channel, so there
2508 * will be no non-opaque pixels in the color-map; it will just be
2509 * grayscale.
2510 */
2511 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2512 png_error(png_ptr, "rgb[gray] color-map: too few entries");
2513
2514 /* Ideally this code would use libpng to do the gamma correction,
2515 * but if an input alpha channel is to be removed we will hit the
2516 * libpng bug in gamma+compose+rgb-to-gray (the double gamma
2517 * correction bug). Fix this by dropping the gamma correction in
2518 * this case and doing it in the palette; this will result in
2519 * duplicate palette entries, but that's better than the
2520 * alternative of double gamma correction.
2521 */
2522 if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2523 png_ptr->num_trans > 0) &&
2524 png_gamma_not_sRGB(png_ptr->colorspace.gamma) != 0)
2525 {
2526 cmap_entries = make_gray_file_colormap(display);
2527 data_encoding = P_FILE;
2528 }
2529
2530 else
2531 cmap_entries = make_gray_colormap(display);
2532
2533 /* But if the input has alpha or transparency it must be removed
2534 */
2535 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2536 png_ptr->num_trans > 0)
2537 {
2538 png_color_16 c;
2539 png_uint_32 gray = back_g;
2540
2541 /* We need to ensure that the application background exists in
2542 * the colormap and that completely transparent pixels map to
2543 * it. Achieve this simply by ensuring that the entry
2544 * selected for the background really is the background color.
2545 */
2546 if (data_encoding == P_FILE) /* from the fixup above */
2547 {
2548 /* The app supplied a gray which is in output_encoding, we
2549 * need to convert it to a value of the input (P_FILE)
2550 * encoding then set this palette entry to the required
2551 * output encoding.
2552 */
2553 if (output_encoding == P_sRGB)
2554 gray = png_sRGB_table[gray]; /* now P_LINEAR */
2555
2556 gray = PNG_DIV257(png_gamma_16bit_correct(gray,
2557 png_ptr->colorspace.gamma)); /* now P_FILE */
2558
2559 /* And make sure the corresponding palette entry contains
2560 * exactly the required sRGB value.
2561 */
2562 png_create_colormap_entry(display, gray, back_g, back_g,
2563 back_g, 0/*unused*/, output_encoding);
2564 }
2565
2566 else if (output_encoding == P_LINEAR)
2567 {
2568 gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2569
2570 /* And make sure the corresponding palette entry matches.
2571 */
2572 png_create_colormap_entry(display, gray, back_g, back_g,
2573 back_g, 0/*unused*/, P_LINEAR);
2574 }
2575
2576 /* The background passed to libpng, however, must be the
2577 * output (normally sRGB) value.
2578 */
2579 c.index = 0; /*unused*/
2580 c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2581
2582 /* NOTE: the following is apparently a bug in libpng. Without
2583 * it the transparent color recognition in
2584 * png_set_background_fixed seems to go wrong.
2585 */
2586 expand_tRNS = 1;
2587 png_set_background_fixed(png_ptr, &c,
2588 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2589 0/*gamma: not used*/);
2590 }
2591
2592 output_processing = PNG_CMAP_NONE;
2593 }
2594 }
2595
2596 else /* output is color */
2597 {
2598 /* We could use png_quantize here so long as there is no transparent
2599 * color or alpha; png_quantize ignores alpha. Easier overall just
2600 * to do it once and using PNG_DIV51 on the 6x6x6 reduced RGB cube.
2601 * Consequently we always want libpng to produce sRGB data.
2602 */
2603 data_encoding = P_sRGB;
2604
2605 /* Is there any transparency or alpha? */
2606 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2607 png_ptr->num_trans > 0)
2608 {
2609 /* Is there alpha in the output too? If so all four channels are
2610 * processed into a special RGB cube with alpha support.
2611 */
2612 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2613 {
2614 png_uint_32 r;
2615
2616 if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
2617 png_error(png_ptr, "rgb+alpha color-map: too few entries");
2618
2619 cmap_entries = make_rgb_colormap(display);
2620
2621 /* Add a transparent entry. */
2622 png_create_colormap_entry(display, cmap_entries, 255, 255,
2623 255, 0, P_sRGB);
2624
2625 /* This is stored as the background index for the processing
2626 * algorithm.
2627 */
2628 background_index = cmap_entries++;
2629
2630 /* Add 27 r,g,b entries each with alpha 0.5. */
2631 for (r=0; r<256; r = (r << 1) | 0x7f)
2632 {
2633 png_uint_32 g;
2634
2635 for (g=0; g<256; g = (g << 1) | 0x7f)
2636 {
2637 png_uint_32 b;
2638
2639 /* This generates components with the values 0, 127 and
2640 * 255
2641 */
2642 for (b=0; b<256; b = (b << 1) | 0x7f)
2643 png_create_colormap_entry(display, cmap_entries++,
2644 r, g, b, 128, P_sRGB);
2645 }
2646 }
2647
2648 expand_tRNS = 1;
2649 output_processing = PNG_CMAP_RGB_ALPHA;
2650 }
2651
2652 else
2653 {
2654 /* Alpha/transparency must be removed. The background must
2655 * exist in the color map (achieved by setting adding it after
2656 * the 666 color-map). If the standard processing code will
2657 * pick up this entry automatically that's all that is
2658 * required; libpng can be called to do the background
2659 * processing.
2660 */
2661 unsigned int sample_size =
2662 PNG_IMAGE_SAMPLE_SIZE(output_format);
2663 png_uint_32 r, g, b; /* sRGB background */
2664
2665 if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
2666 png_error(png_ptr, "rgb-alpha color-map: too few entries");
2667
2668 cmap_entries = make_rgb_colormap(display);
2669
2670 png_create_colormap_entry(display, cmap_entries, back_r,
2671 back_g, back_b, 0/*unused*/, output_encoding);
2672
2673 if (output_encoding == P_LINEAR)
2674 {
2675 r = PNG_sRGB_FROM_LINEAR(back_r * 255);
2676 g = PNG_sRGB_FROM_LINEAR(back_g * 255);
2677 b = PNG_sRGB_FROM_LINEAR(back_b * 255);
2678 }
2679
2680 else
2681 {
2682 r = back_r;
2683 g = back_g;
2684 b = back_g;
2685 }
2686
2687 /* Compare the newly-created color-map entry with the one the
2688 * PNG_CMAP_RGB algorithm will use. If the two entries don't
2689 * match, add the new one and set this as the background
2690 * index.
2691 */
2692 if (memcmp((png_const_bytep)display->colormap +
2693 sample_size * cmap_entries,
2694 (png_const_bytep)display->colormap +
2695 sample_size * PNG_RGB_INDEX(r,g,b),
2696 sample_size) != 0)
2697 {
2698 /* The background color must be added. */
2699 background_index = cmap_entries++;
2700
2701 /* Add 27 r,g,b entries each with created by composing with
2702 * the background at alpha 0.5.
2703 */
2704 for (r=0; r<256; r = (r << 1) | 0x7f)
2705 {
2706 for (g=0; g<256; g = (g << 1) | 0x7f)
2707 {
2708 /* This generates components with the values 0, 127
2709 * and 255
2710 */
2711 for (b=0; b<256; b = (b << 1) | 0x7f)
2712 png_create_colormap_entry(display, cmap_entries++,
2713 png_colormap_compose(display, r, P_sRGB, 128,
2714 back_r, output_encoding),
2715 png_colormap_compose(display, g, P_sRGB, 128,
2716 back_g, output_encoding),
2717 png_colormap_compose(display, b, P_sRGB, 128,
2718 back_b, output_encoding),
2719 0/*unused*/, output_encoding);
2720 }
2721 }
2722
2723 expand_tRNS = 1;
2724 output_processing = PNG_CMAP_RGB_ALPHA;
2725 }
2726
2727 else /* background color is in the standard color-map */
2728 {
2729 png_color_16 c;
2730
2731 c.index = 0; /*unused*/
2732 c.red = (png_uint_16)back_r;
2733 c.gray = c.green = (png_uint_16)back_g;
2734 c.blue = (png_uint_16)back_b;
2735
2736 png_set_background_fixed(png_ptr, &c,
2737 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2738 0/*gamma: not used*/);
2739
2740 output_processing = PNG_CMAP_RGB;
2741 }
2742 }
2743 }
2744
2745 else /* no alpha or transparency in the input */
2746 {
2747 /* Alpha in the output is irrelevant, simply map the opaque input
2748 * pixels to the 6x6x6 color-map.
2749 */
2750 if (PNG_RGB_COLORMAP_ENTRIES > image->colormap_entries)
2751 png_error(png_ptr, "rgb color-map: too few entries");
2752
2753 cmap_entries = make_rgb_colormap(display);
2754 output_processing = PNG_CMAP_RGB;
2755 }
2756 }
2757 break;
2758
2759 case PNG_COLOR_TYPE_PALETTE:
2760 /* It's already got a color-map. It may be necessary to eliminate the
2761 * tRNS entries though.
2762 */
2763 {
2764 unsigned int num_trans = png_ptr->num_trans;
2765 png_const_bytep trans = num_trans > 0 ? png_ptr->trans_alpha : NULL;
2766 png_const_colorp colormap = png_ptr->palette;
2767 const int do_background = trans != NULL &&
2768 (output_format & PNG_FORMAT_FLAG_ALPHA) == 0;
2769 unsigned int i;
2770
2771 /* Just in case: */
2772 if (trans == NULL)
2773 num_trans = 0;
2774
2775 output_processing = PNG_CMAP_NONE;
2776 data_encoding = P_FILE; /* Don't change from color-map indices */
2777 cmap_entries = png_ptr->num_palette;
2778 if (cmap_entries > 256)
2779 cmap_entries = 256;
2780
2781 if (cmap_entries > image->colormap_entries)
2782 png_error(png_ptr, "palette color-map: too few entries");
2783
2784 for (i=0; i < cmap_entries; ++i)
2785 {
2786 if (do_background != 0 && i < num_trans && trans[i] < 255)
2787 {
2788 if (trans[i] == 0)
2789 png_create_colormap_entry(display, i, back_r, back_g,
2790 back_b, 0, output_encoding);
2791
2792 else
2793 {
2794 /* Must compose the PNG file color in the color-map entry
2795 * on the sRGB color in 'back'.
2796 */
2797 png_create_colormap_entry(display, i,
2798 png_colormap_compose(display, colormap[i].red, P_FILE,
2799 trans[i], back_r, output_encoding),
2800 png_colormap_compose(display, colormap[i].green, P_FILE,
2801 trans[i], back_g, output_encoding),
2802 png_colormap_compose(display, colormap[i].blue, P_FILE,
2803 trans[i], back_b, output_encoding),
2804 output_encoding == P_LINEAR ? trans[i] * 257U :
2805 trans[i],
2806 output_encoding);
2807 }
2808 }
2809
2810 else
2811 png_create_colormap_entry(display, i, colormap[i].red,
2812 colormap[i].green, colormap[i].blue,
2813 i < num_trans ? trans[i] : 255U, P_FILE/*8-bit*/);
2814 }
2815
2816 /* The PNG data may have indices packed in fewer than 8 bits, it
2817 * must be expanded if so.
2818 */
2819 if (png_ptr->bit_depth < 8)
2820 png_set_packing(png_ptr);
2821 }
2822 break;
2823
2824 default:
2825 png_error(png_ptr, "invalid PNG color type");
2826 /*NOT REACHED*/
2827 break;
2828 }
2829
2830 /* Now deal with the output processing */
2831 if (expand_tRNS != 0 && png_ptr->num_trans > 0 &&
2832 (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0)
2833 png_set_tRNS_to_alpha(png_ptr);
2834
2835 switch (data_encoding)
2836 {
2837 default:
2838 png_error(png_ptr, "bad data option (internal error)");
2839 break;
2840
2841 case P_sRGB:
2842 /* Change to 8-bit sRGB */
2843 png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB);
2844 /* FALL THROUGH */
2845
2846 case P_FILE:
2847 if (png_ptr->bit_depth > 8)
2848 png_set_scale_16(png_ptr);
2849 break;
2850 }
2851
2852 if (cmap_entries > 256 || cmap_entries > image->colormap_entries)
2853 png_error(png_ptr, "color map overflow (BAD internal error)");
2854
2855 image->colormap_entries = cmap_entries;
2856
2857 /* Double check using the recorded background index */
2858 switch (output_processing)
2859 {
2860 case PNG_CMAP_NONE:
2861 if (background_index != PNG_CMAP_NONE_BACKGROUND)
2862 goto bad_background;
2863 break;
2864
2865 case PNG_CMAP_GA:
2866 if (background_index != PNG_CMAP_GA_BACKGROUND)
2867 goto bad_background;
2868 break;
2869
2870 case PNG_CMAP_TRANS:
2871 if (background_index >= cmap_entries ||
2872 background_index != PNG_CMAP_TRANS_BACKGROUND)
2873 goto bad_background;
2874 break;
2875
2876 case PNG_CMAP_RGB:
2877 if (background_index != PNG_CMAP_RGB_BACKGROUND)
2878 goto bad_background;
2879 break;
2880
2881 case PNG_CMAP_RGB_ALPHA:
2882 if (background_index != PNG_CMAP_RGB_ALPHA_BACKGROUND)
2883 goto bad_background;
2884 break;
2885
2886 default:
2887 png_error(png_ptr, "bad processing option (internal error)");
2888
2889 bad_background:
2890 png_error(png_ptr, "bad background index (internal error)");
2891 }
2892
2893 display->colormap_processing = output_processing;
2894
2895 return 1/*ok*/;
2896 }
2897
2898 /* The final part of the color-map read called from png_image_finish_read. */
2899 static int
2900 png_image_read_and_map(png_voidp argument)
2901 {
2902 png_image_read_control *display = png_voidcast(png_image_read_control*,
2903 argument);
2904 png_imagep image = display->image;
2905 png_structrp png_ptr = image->opaque->png_ptr;
2906 int passes;
2907
2908 /* Called when the libpng data must be transformed into the color-mapped
2909 * form. There is a local row buffer in display->local and this routine must
2910 * do the interlace handling.
2911 */
2912 switch (png_ptr->interlaced)
2913 {
2914 case PNG_INTERLACE_NONE:
2915 passes = 1;
2916 break;
2917
2918 case PNG_INTERLACE_ADAM7:
2919 passes = PNG_INTERLACE_ADAM7_PASSES;
2920 break;
2921
2922 default:
2923 png_error(png_ptr, "unknown interlace type");
2924 }
2925
2926 {
2927 png_uint_32 height = image->height;
2928 png_uint_32 width = image->width;
2929 int proc = display->colormap_processing;
2930 png_bytep first_row = png_voidcast(png_bytep, display->first_row);
2931 ptrdiff_t step_row = display->row_bytes;
2932 int pass;
2933
2934 for (pass = 0; pass < passes; ++pass)
2935 {
2936 unsigned int startx, stepx, stepy;
2937 png_uint_32 y;
2938
2939 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
2940 {
2941 /* The row may be empty for a short image: */
2942 if (PNG_PASS_COLS(width, pass) == 0)
2943 continue;
2944
2945 startx = PNG_PASS_START_COL(pass);
2946 stepx = PNG_PASS_COL_OFFSET(pass);
2947 y = PNG_PASS_START_ROW(pass);
2948 stepy = PNG_PASS_ROW_OFFSET(pass);
2949 }
2950
2951 else
2952 {
2953 y = 0;
2954 startx = 0;
2955 stepx = stepy = 1;
2956 }
2957
2958 for (; y<height; y += stepy)
2959 {
2960 png_bytep inrow = png_voidcast(png_bytep, display->local_row);
2961 png_bytep outrow = first_row + y * step_row;
2962 png_const_bytep end_row = outrow + width;
2963
2964 /* Read read the libpng data into the temporary buffer. */
2965 png_read_row(png_ptr, inrow, NULL);
2966
2967 /* Now process the row according to the processing option, note
2968 * that the caller verifies that the format of the libpng output
2969 * data is as required.
2970 */
2971 outrow += startx;
2972 switch (proc)
2973 {
2974 case PNG_CMAP_GA:
2975 for (; outrow < end_row; outrow += stepx)
2976 {
2977 /* The data is always in the PNG order */
2978 unsigned int gray = *inrow++;
2979 unsigned int alpha = *inrow++;
2980 unsigned int entry;
2981
2982 /* NOTE: this code is copied as a comment in
2983 * make_ga_colormap above. Please update the
2984 * comment if you change this code!
2985 */
2986 if (alpha > 229) /* opaque */
2987 {
2988 entry = (231 * gray + 128) >> 8;
2989 }
2990 else if (alpha < 26) /* transparent */
2991 {
2992 entry = 231;
2993 }
2994 else /* partially opaque */
2995 {
2996 entry = 226 + 6 * PNG_DIV51(alpha) + PNG_DIV51(gray);
2997 }
2998
2999 *outrow = (png_byte)entry;
3000 }
3001 break;
3002
3003 case PNG_CMAP_TRANS:
3004 for (; outrow < end_row; outrow += stepx)
3005 {
3006 png_byte gray = *inrow++;
3007 png_byte alpha = *inrow++;
3008
3009 if (alpha == 0)
3010 *outrow = PNG_CMAP_TRANS_BACKGROUND;
3011
3012 else if (gray != PNG_CMAP_TRANS_BACKGROUND)
3013 *outrow = gray;
3014
3015 else
3016 *outrow = (png_byte)(PNG_CMAP_TRANS_BACKGROUND+1);
3017 }
3018 break;
3019
3020 case PNG_CMAP_RGB:
3021 for (; outrow < end_row; outrow += stepx)
3022 {
3023 *outrow = PNG_RGB_INDEX(inrow[0], inrow[1], inrow[2]);
3024 inrow += 3;
3025 }
3026 break;
3027
3028 case PNG_CMAP_RGB_ALPHA:
3029 for (; outrow < end_row; outrow += stepx)
3030 {
3031 unsigned int alpha = inrow[3];
3032
3033 /* Because the alpha entries only hold alpha==0.5 values
3034 * split the processing at alpha==0.25 (64) and 0.75
3035 * (196).
3036 */
3037
3038 if (alpha >= 196)
3039 *outrow = PNG_RGB_INDEX(inrow[0], inrow[1],
3040 inrow[2]);
3041
3042 else if (alpha < 64)
3043 *outrow = PNG_CMAP_RGB_ALPHA_BACKGROUND;
3044
3045 else
3046 {
3047 /* Likewise there are three entries for each of r, g
3048 * and b. We could select the entry by popcount on
3049 * the top two bits on those architectures that
3050 * support it, this is what the code below does,
3051 * crudely.
3052 */
3053 unsigned int back_i = PNG_CMAP_RGB_ALPHA_BACKGROUND+1;
3054
3055 /* Here are how the values map:
3056 *
3057 * 0x00 .. 0x3f -> 0
3058 * 0x40 .. 0xbf -> 1
3059 * 0xc0 .. 0xff -> 2
3060 *
3061 * So, as above with the explicit alpha checks, the
3062 * breakpoints are at 64 and 196.
3063 */
3064 if (inrow[0] & 0x80) back_i += 9; /* red */
3065 if (inrow[0] & 0x40) back_i += 9;
3066 if (inrow[0] & 0x80) back_i += 3; /* green */
3067 if (inrow[0] & 0x40) back_i += 3;
3068 if (inrow[0] & 0x80) back_i += 1; /* blue */
3069 if (inrow[0] & 0x40) back_i += 1;
3070
3071 *outrow = (png_byte)back_i;
3072 }
3073
3074 inrow += 4;
3075 }
3076 break;
3077
3078 default:
3079 break;
3080 }
3081 }
3082 }
3083 }
3084
3085 return 1;
3086 }
3087
3088 static int
3089 png_image_read_colormapped(png_voidp argument)
3090 {
3091 png_image_read_control *display = png_voidcast(png_image_read_control*,
3092 argument);
3093 png_imagep image = display->image;
3094 png_controlp control = image->opaque;
3095 png_structrp png_ptr = control->png_ptr;
3096 png_inforp info_ptr = control->info_ptr;
3097
3098 int passes = 0; /* As a flag */
3099
3100 PNG_SKIP_CHUNKS(png_ptr);
3101
3102 /* Update the 'info' structure and make sure the result is as required; first
3103 * make sure to turn on the interlace handling if it will be required
3104 * (because it can't be turned on *after* the call to png_read_update_info!)
3105 */
3106 if (display->colormap_processing == PNG_CMAP_NONE)
3107 passes = png_set_interlace_handling(png_ptr);
3108
3109 png_read_update_info(png_ptr, info_ptr);
3110
3111 /* The expected output can be deduced from the colormap_processing option. */
3112 switch (display->colormap_processing)
3113 {
3114 case PNG_CMAP_NONE:
3115 /* Output must be one channel and one byte per pixel, the output
3116 * encoding can be anything.
3117 */
3118 if ((info_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
3119 info_ptr->color_type == PNG_COLOR_TYPE_GRAY) &&
3120 info_ptr->bit_depth == 8)
3121 break;
3122
3123 goto bad_output;
3124
3125 case PNG_CMAP_TRANS:
3126 case PNG_CMAP_GA:
3127 /* Output must be two channels and the 'G' one must be sRGB, the latter
3128 * can be checked with an exact number because it should have been set
3129 * to this number above!
3130 */
3131 if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA &&
3132 info_ptr->bit_depth == 8 &&
3133 png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3134 image->colormap_entries == 256)
3135 break;
3136
3137 goto bad_output;
3138
3139 case PNG_CMAP_RGB:
3140 /* Output must be 8-bit sRGB encoded RGB */
3141 if (info_ptr->color_type == PNG_COLOR_TYPE_RGB &&
3142 info_ptr->bit_depth == 8 &&
3143 png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3144 image->colormap_entries == 216)
3145 break;
3146
3147 goto bad_output;
3148
3149 case PNG_CMAP_RGB_ALPHA:
3150 /* Output must be 8-bit sRGB encoded RGBA */
3151 if (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
3152 info_ptr->bit_depth == 8 &&
3153 png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3154 image->colormap_entries == 244 /* 216 + 1 + 27 */)
3155 break;
3156
3157 /* goto bad_output; */
3158 /* FALL THROUGH */
3159
3160 default:
3161 bad_output:
3162 png_error(png_ptr, "bad color-map processing (internal error)");
3163 }
3164
3165 /* Now read the rows. Do this here if it is possible to read directly into
3166 * the output buffer, otherwise allocate a local row buffer of the maximum
3167 * size libpng requires and call the relevant processing routine safely.
3168 */
3169 {
3170 png_voidp first_row = display->buffer;
3171 ptrdiff_t row_bytes = display->row_stride;
3172
3173 /* The following expression is designed to work correctly whether it gives
3174 * a signed or an unsigned result.
3175 */
3176 if (row_bytes < 0)
3177 {
3178 char *ptr = png_voidcast(char*, first_row);
3179 ptr += (image->height-1) * (-row_bytes);
3180 first_row = png_voidcast(png_voidp, ptr);
3181 }
3182
3183 display->first_row = first_row;
3184 display->row_bytes = row_bytes;
3185 }
3186
3187 if (passes == 0)
3188 {
3189 int result;
3190 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
3191
3192 display->local_row = row;
3193 result = png_safe_execute(image, png_image_read_and_map, display);
3194 display->local_row = NULL;
3195 png_free(png_ptr, row);
3196
3197 return result;
3198 }
3199
3200 else
3201 {
3202 png_alloc_size_t row_bytes = display->row_bytes;
3203
3204 while (--passes >= 0)
3205 {
3206 png_uint_32 y = image->height;
3207 png_bytep row = png_voidcast(png_bytep, display->first_row);
3208
3209 while (y-- > 0)
3210 {
3211 png_read_row(png_ptr, row, NULL);
3212 row += row_bytes;
3213 }
3214 }
3215
3216 return 1;
3217 }
3218 }
3219
3220 /* Just the row reading part of png_image_read. */
3221 static int
3222 png_image_read_composite(png_voidp argument)
3223 {
3224 png_image_read_control *display = png_voidcast(png_image_read_control*,
3225 argument);
3226 png_imagep image = display->image;
3227 png_structrp png_ptr = image->opaque->png_ptr;
3228 int passes;
3229
3230 switch (png_ptr->interlaced)
3231 {
3232 case PNG_INTERLACE_NONE:
3233 passes = 1;
3234 break;
3235
3236 case PNG_INTERLACE_ADAM7:
3237 passes = PNG_INTERLACE_ADAM7_PASSES;
3238 break;
3239
3240 default:
3241 png_error(png_ptr, "unknown interlace type");
3242 }
3243
3244 {
3245 png_uint_32 height = image->height;
3246 png_uint_32 width = image->width;
3247 ptrdiff_t step_row = display->row_bytes;
3248 unsigned int channels =
3249 (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
3250 int pass;
3251
3252 for (pass = 0; pass < passes; ++pass)
3253 {
3254 unsigned int startx, stepx, stepy;
3255 png_uint_32 y;
3256
3257 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3258 {
3259 /* The row may be empty for a short image: */
3260 if (PNG_PASS_COLS(width, pass) == 0)
3261 continue;
3262
3263 startx = PNG_PASS_START_COL(pass) * channels;
3264 stepx = PNG_PASS_COL_OFFSET(pass) * channels;
3265 y = PNG_PASS_START_ROW(pass);
3266 stepy = PNG_PASS_ROW_OFFSET(pass);
3267 }
3268
3269 else
3270 {
3271 y = 0;
3272 startx = 0;
3273 stepx = channels;
3274 stepy = 1;
3275 }
3276
3277 for (; y<height; y += stepy)
3278 {
3279 png_bytep inrow = png_voidcast(png_bytep, display->local_row);
3280 png_bytep outrow;
3281 png_const_bytep end_row;
3282
3283 /* Read the row, which is packed: */
3284 png_read_row(png_ptr, inrow, NULL);
3285
3286 outrow = png_voidcast(png_bytep, display->first_row);
3287 outrow += y * step_row;
3288 end_row = outrow + width * channels;
3289
3290 /* Now do the composition on each pixel in this row. */
3291 outrow += startx;
3292 for (; outrow < end_row; outrow += stepx)
3293 {
3294 png_byte alpha = inrow[channels];
3295
3296 if (alpha > 0) /* else no change to the output */
3297 {
3298 unsigned int c;
3299
3300 for (c=0; c<channels; ++c)
3301 {
3302 png_uint_32 component = inrow[c];
3303
3304 if (alpha < 255) /* else just use component */
3305 {
3306 /* This is PNG_OPTIMIZED_ALPHA, the component value
3307 * is a linear 8-bit value. Combine this with the
3308 * current outrow[c] value which is sRGB encoded.
3309 * Arithmetic here is 16-bits to preserve the output
3310 * values correctly.
3311 */
3312 component *= 257*255; /* =65535 */
3313 component += (255-alpha)*png_sRGB_table[outrow[c]];
3314
3315 /* So 'component' is scaled by 255*65535 and is
3316 * therefore appropriate for the sRGB to linear
3317 * conversion table.
3318 */
3319 component = PNG_sRGB_FROM_LINEAR(component);
3320 }
3321
3322 outrow[c] = (png_byte)component;
3323 }
3324 }
3325
3326 inrow += channels+1; /* components and alpha channel */
3327 }
3328 }
3329 }
3330 }
3331
3332 return 1;
3333 }
3334
3335 /* The do_local_background case; called when all the following transforms are to
3336 * be done:
3337 *
3338 * PNG_RGB_TO_GRAY
3339 * PNG_COMPOSITE
3340 * PNG_GAMMA
3341 *
3342 * This is a work-around for the fact that both the PNG_RGB_TO_GRAY and
3343 * PNG_COMPOSITE code performs gamma correction, so we get double gamma
3344 * correction. The fix-up is to prevent the PNG_COMPOSITE operation from
3345 * happening inside libpng, so this routine sees an 8 or 16-bit gray+alpha
3346 * row and handles the removal or pre-multiplication of the alpha channel.
3347 */
3348 static int
3349 png_image_read_background(png_voidp argument)
3350 {
3351 png_image_read_control *display = png_voidcast(png_image_read_control*,
3352 argument);
3353 png_imagep image = display->image;
3354 png_structrp png_ptr = image->opaque->png_ptr;
3355 png_inforp info_ptr = image->opaque->info_ptr;
3356 png_uint_32 height = image->height;
3357 png_uint_32 width = image->width;
3358 int pass, passes;
3359
3360 /* Double check the convoluted logic below. We expect to get here with
3361 * libpng doing rgb to gray and gamma correction but background processing
3362 * left to the png_image_read_background function. The rows libpng produce
3363 * might be 8 or 16-bit but should always have two channels; gray plus alpha.
3364 */
3365 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
3366 png_error(png_ptr, "lost rgb to gray");
3367
3368 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
3369 png_error(png_ptr, "unexpected compose");
3370
3371 if (png_get_channels(png_ptr, info_ptr) != 2)
3372 png_error(png_ptr, "lost/gained channels");
3373
3374 /* Expect the 8-bit case to always remove the alpha channel */
3375 if ((image->format & PNG_FORMAT_FLAG_LINEAR) == 0 &&
3376 (image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
3377 png_error(png_ptr, "unexpected 8-bit transformation");
3378
3379 switch (png_ptr->interlaced)
3380 {
3381 case PNG_INTERLACE_NONE:
3382 passes = 1;
3383 break;
3384
3385 case PNG_INTERLACE_ADAM7:
3386 passes = PNG_INTERLACE_ADAM7_PASSES;
3387 break;
3388
3389 default:
3390 png_error(png_ptr, "unknown interlace type");
3391 }
3392
3393 /* Use direct access to info_ptr here because otherwise the simplified API
3394 * would require PNG_EASY_ACCESS_SUPPORTED (just for this.) Note this is
3395 * checking the value after libpng expansions, not the original value in the
3396 * PNG.
3397 */
3398 switch (info_ptr->bit_depth)
3399 {
3400 default:
3401 png_error(png_ptr, "unexpected bit depth");
3402 break;
3403
3404 case 8:
3405 /* 8-bit sRGB gray values with an alpha channel; the alpha channel is
3406 * to be removed by composing on a background: either the row if
3407 * display->background is NULL or display->background->green if not.
3408 * Unlike the code above ALPHA_OPTIMIZED has *not* been done.
3409 */
3410 {
3411 png_bytep first_row = png_voidcast(png_bytep, display->first_row);
3412 ptrdiff_t step_row = display->row_bytes;
3413
3414 for (pass = 0; pass < passes; ++pass)
3415 {
3416 png_bytep row = png_voidcast(png_bytep,
3417 display->first_row);
3418 unsigned int startx, stepx, stepy;
3419 png_uint_32 y;
3420
3421 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3422 {
3423 /* The row may be empty for a short image: */
3424 if (PNG_PASS_COLS(width, pass) == 0)
3425 continue;
3426
3427 startx = PNG_PASS_START_COL(pass);
3428 stepx = PNG_PASS_COL_OFFSET(pass);
3429 y = PNG_PASS_START_ROW(pass);
3430 stepy = PNG_PASS_ROW_OFFSET(pass);
3431 }
3432
3433 else
3434 {
3435 y = 0;
3436 startx = 0;
3437 stepx = stepy = 1;
3438 }
3439
3440 if (display->background == NULL)
3441 {
3442 for (; y<height; y += stepy)
3443 {
3444 png_bytep inrow = png_voidcast(png_bytep,
3445 display->local_row);
3446 png_bytep outrow = first_row + y * step_row;
3447 png_const_bytep end_row = outrow + width;
3448
3449 /* Read the row, which is packed: */
3450 png_read_row(png_ptr, inrow, NULL);
3451
3452 /* Now do the composition on each pixel in this row. */
3453 outrow += startx;
3454 for (; outrow < end_row; outrow += stepx)
3455 {
3456 png_byte alpha = inrow[1];
3457
3458 if (alpha > 0) /* else no change to the output */
3459 {
3460 png_uint_32 component = inrow[0];
3461
3462 if (alpha < 255) /* else just use component */
3463 {
3464 /* Since PNG_OPTIMIZED_ALPHA was not set it is
3465 * necessary to invert the sRGB transfer
3466 * function and multiply the alpha out.
3467 */
3468 component = png_sRGB_table[component] * alpha;
3469 component += png_sRGB_table[outrow[0]] *
3470 (255-alpha);
3471 component = PNG_sRGB_FROM_LINEAR(component);
3472 }
3473
3474 outrow[0] = (png_byte)component;
3475 }
3476
3477 inrow += 2; /* gray and alpha channel */
3478 }
3479 }
3480 }
3481
3482 else /* constant background value */
3483 {
3484 png_byte background8 = display->background->green;
3485 png_uint_16 background = png_sRGB_table[background8];
3486
3487 for (; y<height; y += stepy)
3488 {
3489 png_bytep inrow = png_voidcast(png_bytep,
3490 display->local_row);
3491 png_bytep outrow = first_row + y * step_row;
3492 png_const_bytep end_row = outrow + width;
3493
3494 /* Read the row, which is packed: */
3495 png_read_row(png_ptr, inrow, NULL);
3496
3497 /* Now do the composition on each pixel in this row. */
3498 outrow += startx;
3499 for (; outrow < end_row; outrow += stepx)
3500 {
3501 png_byte alpha = inrow[1];
3502
3503 if (alpha > 0) /* else use background */
3504 {
3505 png_uint_32 component = inrow[0];
3506
3507 if (alpha < 255) /* else just use component */
3508 {
3509 component = png_sRGB_table[component] * alpha;
3510 component += background * (255-alpha);
3511 component = PNG_sRGB_FROM_LINEAR(component);
3512 }
3513
3514 outrow[0] = (png_byte)component;
3515 }
3516
3517 else
3518 outrow[0] = background8;
3519
3520 inrow += 2; /* gray and alpha channel */
3521 }
3522
3523 row += display->row_bytes;
3524 }
3525 }
3526 }
3527 }
3528 break;
3529
3530 case 16:
3531 /* 16-bit linear with pre-multiplied alpha; the pre-multiplication must
3532 * still be done and, maybe, the alpha channel removed. This code also
3533 * handles the alpha-first option.
3534 */
3535 {
3536 png_uint_16p first_row = png_voidcast(png_uint_16p,
3537 display->first_row);
3538 /* The division by two is safe because the caller passed in a
3539 * stride which was multiplied by 2 (below) to get row_bytes.
3540 */
3541 ptrdiff_t step_row = display->row_bytes / 2;
3542 int preserve_alpha = (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
3543 unsigned int outchannels = 1+preserve_alpha;
3544 int swap_alpha = 0;
3545
3546 # ifdef PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED
3547 if (preserve_alpha != 0 &&
3548 (image->format & PNG_FORMAT_FLAG_AFIRST) != 0)
3549 swap_alpha = 1;
3550 # endif
3551
3552 for (pass = 0; pass < passes; ++pass)
3553 {
3554 unsigned int startx, stepx, stepy;
3555 png_uint_32 y;
3556
3557 /* The 'x' start and step are adjusted to output components here.
3558 */
3559 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3560 {
3561 /* The row may be empty for a short image: */
3562 if (PNG_PASS_COLS(width, pass) == 0)
3563 continue;
3564
3565 startx = PNG_PASS_START_COL(pass) * outchannels;
3566 stepx = PNG_PASS_COL_OFFSET(pass) * outchannels;
3567 y = PNG_PASS_START_ROW(pass);
3568 stepy = PNG_PASS_ROW_OFFSET(pass);
3569 }
3570
3571 else
3572 {
3573 y = 0;
3574 startx = 0;
3575 stepx = outchannels;
3576 stepy = 1;
3577 }
3578
3579 for (; y<height; y += stepy)
3580 {
3581 png_const_uint_16p inrow;
3582 png_uint_16p outrow = first_row + y*step_row;
3583 png_uint_16p end_row = outrow + width * outchannels;
3584
3585 /* Read the row, which is packed: */
3586 png_read_row(png_ptr, png_voidcast(png_bytep,
3587 display->local_row), NULL);
3588 inrow = png_voidcast(png_const_uint_16p, display->local_row);
3589
3590 /* Now do the pre-multiplication on each pixel in this row.
3591 */
3592 outrow += startx;
3593 for (; outrow < end_row; outrow += stepx)
3594 {
3595 png_uint_32 component = inrow[0];
3596 png_uint_16 alpha = inrow[1];
3597
3598 if (alpha > 0) /* else 0 */
3599 {
3600 if (alpha < 65535) /* else just use component */
3601 {
3602 component *= alpha;
3603 component += 32767;
3604 component /= 65535;
3605 }
3606 }
3607
3608 else
3609 component = 0;
3610
3611 outrow[swap_alpha] = (png_uint_16)component;
3612 if (preserve_alpha != 0)
3613 outrow[1 ^ swap_alpha] = alpha;
3614
3615 inrow += 2; /* components and alpha channel */
3616 }
3617 }
3618 }
3619 }
3620 break;
3621 }
3622
3623 return 1;
3624 }
3625
3626 /* The guts of png_image_finish_read as a png_safe_execute callback. */
3627 static int
3628 png_image_read_direct(png_voidp argument)
3629 {
3630 png_image_read_control *display = png_voidcast(png_image_read_control*,
3631 argument);
3632 png_imagep image = display->image;
3633 png_structrp png_ptr = image->opaque->png_ptr;
3634 png_inforp info_ptr = image->opaque->info_ptr;
3635
3636 png_uint_32 format = image->format;
3637 int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0;
3638 int do_local_compose = 0;
3639 int do_local_background = 0; /* to avoid double gamma correction bug */
3640 int passes = 0;
3641
3642 /* Add transforms to ensure the correct output format is produced then check
3643 * that the required implementation support is there. Always expand; always
3644 * need 8 bits minimum, no palette and expanded tRNS.
3645 */
3646 png_set_expand(png_ptr);
3647
3648 /* Now check the format to see if it was modified. */
3649 {
3650 png_uint_32 base_format = png_image_format(png_ptr) &
3651 ~PNG_FORMAT_FLAG_COLORMAP /* removed by png_set_expand */;
3652 png_uint_32 change = format ^ base_format;
3653 png_fixed_point output_gamma;
3654 int mode; /* alpha mode */
3655
3656 /* Do this first so that we have a record if rgb to gray is happening. */
3657 if ((change & PNG_FORMAT_FLAG_COLOR) != 0)
3658 {
3659 /* gray<->color transformation required. */
3660 if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
3661 png_set_gray_to_rgb(png_ptr);
3662
3663 else
3664 {
3665 /* libpng can't do both rgb to gray and
3666 * background/pre-multiplication if there is also significant gamma
3667 * correction, because both operations require linear colors and
3668 * the code only supports one transform doing the gamma correction.
3669 * Handle this by doing the pre-multiplication or background
3670 * operation in this code, if necessary.
3671 *
3672 * TODO: fix this by rewriting pngrtran.c (!)
3673 *
3674 * For the moment (given that fixing this in pngrtran.c is an
3675 * enormous change) 'do_local_background' is used to indicate that
3676 * the problem exists.
3677 */
3678 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3679 do_local_background = 1/*maybe*/;
3680
3681 png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE,
3682 PNG_RGB_TO_GRAY_DEFAULT, PNG_RGB_TO_GRAY_DEFAULT);
3683 }
3684
3685 change &= ~PNG_FORMAT_FLAG_COLOR;
3686 }
3687
3688 /* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise.
3689 */
3690 {
3691 png_fixed_point input_gamma_default;
3692
3693 if ((base_format & PNG_FORMAT_FLAG_LINEAR) != 0 &&
3694 (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
3695 input_gamma_default = PNG_GAMMA_LINEAR;
3696 else
3697 input_gamma_default = PNG_DEFAULT_sRGB;
3698
3699 /* Call png_set_alpha_mode to set the default for the input gamma; the
3700 * output gamma is set by a second call below.
3701 */
3702 png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, input_gamma_default);
3703 }
3704
3705 if (linear != 0)
3706 {
3707 /* If there *is* an alpha channel in the input it must be multiplied
3708 * out; use PNG_ALPHA_STANDARD, otherwise just use PNG_ALPHA_PNG.
3709 */
3710 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3711 mode = PNG_ALPHA_STANDARD; /* associated alpha */
3712
3713 else
3714 mode = PNG_ALPHA_PNG;
3715
3716 output_gamma = PNG_GAMMA_LINEAR;
3717 }
3718
3719 else
3720 {
3721 mode = PNG_ALPHA_PNG;
3722 output_gamma = PNG_DEFAULT_sRGB;
3723 }
3724
3725 /* If 'do_local_background' is set check for the presence of gamma
3726 * correction; this is part of the work-round for the libpng bug
3727 * described above.
3728 *
3729 * TODO: fix libpng and remove this.
3730 */
3731 if (do_local_background != 0)
3732 {
3733 png_fixed_point gtest;
3734
3735 /* This is 'png_gamma_threshold' from pngrtran.c; the test used for
3736 * gamma correction, the screen gamma hasn't been set on png_struct
3737 * yet; it's set below. png_struct::gamma, however, is set to the
3738 * final value.
3739 */
3740 if (png_muldiv(&gtest, output_gamma, png_ptr->colorspace.gamma,
3741 PNG_FP_1) != 0 && png_gamma_significant(gtest) == 0)
3742 do_local_background = 0;
3743
3744 else if (mode == PNG_ALPHA_STANDARD)
3745 {
3746 do_local_background = 2/*required*/;
3747 mode = PNG_ALPHA_PNG; /* prevent libpng doing it */
3748 }
3749
3750 /* else leave as 1 for the checks below */
3751 }
3752
3753 /* If the bit-depth changes then handle that here. */
3754 if ((change & PNG_FORMAT_FLAG_LINEAR) != 0)
3755 {
3756 if (linear != 0 /*16-bit output*/)
3757 png_set_expand_16(png_ptr);
3758
3759 else /* 8-bit output */
3760 png_set_scale_16(png_ptr);
3761
3762 change &= ~PNG_FORMAT_FLAG_LINEAR;
3763 }
3764
3765 /* Now the background/alpha channel changes. */
3766 if ((change & PNG_FORMAT_FLAG_ALPHA) != 0)
3767 {
3768 /* Removing an alpha channel requires composition for the 8-bit
3769 * formats; for the 16-bit it is already done, above, by the
3770 * pre-multiplication and the channel just needs to be stripped.
3771 */
3772 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3773 {
3774 /* If RGB->gray is happening the alpha channel must be left and the
3775 * operation completed locally.
3776 *
3777 * TODO: fix libpng and remove this.
3778 */
3779 if (do_local_background != 0)
3780 do_local_background = 2/*required*/;
3781
3782 /* 16-bit output: just remove the channel */
3783 else if (linear != 0) /* compose on black (well, pre-multiply) */
3784 png_set_strip_alpha(png_ptr);
3785
3786 /* 8-bit output: do an appropriate compose */
3787 else if (display->background != NULL)
3788 {
3789 png_color_16 c;
3790
3791 c.index = 0; /*unused*/
3792 c.red = display->background->red;
3793 c.green = display->background->green;
3794 c.blue = display->background->blue;
3795 c.gray = display->background->green;
3796
3797 /* This is always an 8-bit sRGB value, using the 'green' channel
3798 * for gray is much better than calculating the luminance here;
3799 * we can get off-by-one errors in that calculation relative to
3800 * the app expectations and that will show up in transparent
3801 * pixels.
3802 */
3803 png_set_background_fixed(png_ptr, &c,
3804 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
3805 0/*gamma: not used*/);
3806 }
3807
3808 else /* compose on row: implemented below. */
3809 {
3810 do_local_compose = 1;
3811 /* This leaves the alpha channel in the output, so it has to be
3812 * removed by the code below. Set the encoding to the 'OPTIMIZE'
3813 * one so the code only has to hack on the pixels that require
3814 * composition.
3815 */
3816 mode = PNG_ALPHA_OPTIMIZED;
3817 }
3818 }
3819
3820 else /* output needs an alpha channel */
3821 {
3822 /* This is tricky because it happens before the swap operation has
3823 * been accomplished; however, the swap does *not* swap the added
3824 * alpha channel (weird API), so it must be added in the correct
3825 * place.
3826 */
3827 png_uint_32 filler; /* opaque filler */
3828 int where;
3829
3830 if (linear != 0)
3831 filler = 65535;
3832
3833 else
3834 filler = 255;
3835
3836 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
3837 if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
3838 {
3839 where = PNG_FILLER_BEFORE;
3840 change &= ~PNG_FORMAT_FLAG_AFIRST;
3841 }
3842
3843 else
3844 # endif
3845 where = PNG_FILLER_AFTER;
3846
3847 png_set_add_alpha(png_ptr, filler, where);
3848 }
3849
3850 /* This stops the (irrelevant) call to swap_alpha below. */
3851 change &= ~PNG_FORMAT_FLAG_ALPHA;
3852 }
3853
3854 /* Now set the alpha mode correctly; this is always done, even if there is
3855 * no alpha channel in either the input or the output because it correctly
3856 * sets the output gamma.
3857 */
3858 png_set_alpha_mode_fixed(png_ptr, mode, output_gamma);
3859
3860 # ifdef PNG_FORMAT_BGR_SUPPORTED
3861 if ((change & PNG_FORMAT_FLAG_BGR) != 0)
3862 {
3863 /* Check only the output format; PNG is never BGR; don't do this if
3864 * the output is gray, but fix up the 'format' value in that case.
3865 */
3866 if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
3867 png_set_bgr(png_ptr);
3868
3869 else
3870 format &= ~PNG_FORMAT_FLAG_BGR;
3871
3872 change &= ~PNG_FORMAT_FLAG_BGR;
3873 }
3874 # endif
3875
3876 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
3877 if ((change & PNG_FORMAT_FLAG_AFIRST) != 0)
3878 {
3879 /* Only relevant if there is an alpha channel - it's particularly
3880 * important to handle this correctly because do_local_compose may
3881 * be set above and then libpng will keep the alpha channel for this
3882 * code to remove.
3883 */
3884 if ((format & PNG_FORMAT_FLAG_ALPHA) != 0)
3885 {
3886 /* Disable this if doing a local background,
3887 * TODO: remove this when local background is no longer required.
3888 */
3889 if (do_local_background != 2)
3890 png_set_swap_alpha(png_ptr);
3891 }
3892
3893 else
3894 format &= ~PNG_FORMAT_FLAG_AFIRST;
3895
3896 change &= ~PNG_FORMAT_FLAG_AFIRST;
3897 }
3898 # endif
3899
3900 /* If the *output* is 16-bit then we need to check for a byte-swap on this
3901 * architecture.
3902 */
3903 if (linear != 0)
3904 {
3905 PNG_CONST png_uint_16 le = 0x0001;
3906
3907 if ((*(png_const_bytep) & le) != 0)
3908 png_set_swap(png_ptr);
3909 }
3910
3911 /* If change is not now 0 some transformation is missing - error out. */
3912 if (change != 0)
3913 png_error(png_ptr, "png_read_image: unsupported transformation");
3914 }
3915
3916 PNG_SKIP_CHUNKS(png_ptr);
3917
3918 /* Update the 'info' structure and make sure the result is as required; first
3919 * make sure to turn on the interlace handling if it will be required
3920 * (because it can't be turned on *after* the call to png_read_update_info!)
3921 *
3922 * TODO: remove the do_local_background fixup below.
3923 */
3924 if (do_local_compose == 0 && do_local_background != 2)
3925 passes = png_set_interlace_handling(png_ptr);
3926
3927 png_read_update_info(png_ptr, info_ptr);
3928
3929 {
3930 png_uint_32 info_format = 0;
3931
3932 if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
3933 info_format |= PNG_FORMAT_FLAG_COLOR;
3934
3935 if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
3936 {
3937 /* do_local_compose removes this channel below. */
3938 if (do_local_compose == 0)
3939 {
3940 /* do_local_background does the same if required. */
3941 if (do_local_background != 2 ||
3942 (format & PNG_FORMAT_FLAG_ALPHA) != 0)
3943 info_format |= PNG_FORMAT_FLAG_ALPHA;
3944 }
3945 }
3946
3947 else if (do_local_compose != 0) /* internal error */
3948 png_error(png_ptr, "png_image_read: alpha channel lost");
3949
3950 if (info_ptr->bit_depth == 16)
3951 info_format |= PNG_FORMAT_FLAG_LINEAR;
3952
3953 # ifdef PNG_FORMAT_BGR_SUPPORTED
3954 if ((png_ptr->transformations & PNG_BGR) != 0)
3955 info_format |= PNG_FORMAT_FLAG_BGR;
3956 # endif
3957
3958 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
3959 if (do_local_background == 2)
3960 {
3961 if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
3962 info_format |= PNG_FORMAT_FLAG_AFIRST;
3963 }
3964
3965 if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0 ||
3966 ((png_ptr->transformations & PNG_ADD_ALPHA) != 0 &&
3967 (png_ptr->flags & PNG_FLAG_FILLER_AFTER) == 0))
3968 {
3969 if (do_local_background == 2)
3970 png_error(png_ptr, "unexpected alpha swap transformation");
3971
3972 info_format |= PNG_FORMAT_FLAG_AFIRST;
3973 }
3974 # endif
3975
3976 /* This is actually an internal error. */
3977 if (info_format != format)
3978 png_error(png_ptr, "png_read_image: invalid transformations");
3979 }
3980
3981 /* Now read the rows. If do_local_compose is set then it is necessary to use
3982 * a local row buffer. The output will be GA, RGBA or BGRA and must be
3983 * converted to G, RGB or BGR as appropriate. The 'local_row' member of the
3984 * display acts as a flag.
3985 */
3986 {
3987 png_voidp first_row = display->buffer;
3988 ptrdiff_t row_bytes = display->row_stride;
3989
3990 if (linear != 0)
3991 row_bytes *= 2;
3992
3993 /* The following expression is designed to work correctly whether it gives
3994 * a signed or an unsigned result.
3995 */
3996 if (row_bytes < 0)
3997 {
3998 char *ptr = png_voidcast(char*, first_row);
3999 ptr += (image->height-1) * (-row_bytes);
4000 first_row = png_voidcast(png_voidp, ptr);
4001 }
4002
4003 display->first_row = first_row;
4004 display->row_bytes = row_bytes;
4005 }
4006
4007 if (do_local_compose != 0)
4008 {
4009 int result;
4010 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
4011
4012 display->local_row = row;
4013 result = png_safe_execute(image, png_image_read_composite, display);
4014 display->local_row = NULL;
4015 png_free(png_ptr, row);
4016
4017 return result;
4018 }
4019
4020 else if (do_local_background == 2)
4021 {
4022 int result;
4023 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
4024
4025 display->local_row = row;
4026 result = png_safe_execute(image, png_image_read_background, display);
4027 display->local_row = NULL;
4028 png_free(png_ptr, row);
4029
4030 return result;
4031 }
4032
4033 else
4034 {
4035 png_alloc_size_t row_bytes = display->row_bytes;
4036
4037 while (--passes >= 0)
4038 {
4039 png_uint_32 y = image->height;
4040 png_bytep row = png_voidcast(png_bytep, display->first_row);
4041
4042 while (y-- > 0)
4043 {
4044 png_read_row(png_ptr, row, NULL);
4045 row += row_bytes;
4046 }
4047 }
4048
4049 return 1;
4050 }
4051 }
4052
4053 int PNGAPI
4054 png_image_finish_read(png_imagep image, png_const_colorp background,
4055 void *buffer, png_int_32 row_stride, void *colormap)
4056 {
4057 if (image != NULL && image->version == PNG_IMAGE_VERSION)
4058 {
4059 png_uint_32 check;
4060
4061 if (row_stride == 0)
4062 row_stride = PNG_IMAGE_ROW_STRIDE(*image);
4063
4064 if (row_stride < 0)
4065 check = -row_stride;
4066
4067 else
4068 check = row_stride;
4069
4070 if (image->opaque != NULL && buffer != NULL &&
4071 check >= PNG_IMAGE_ROW_STRIDE(*image))
4072 {
4073 if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 ||
4074 (image->colormap_entries > 0 && colormap != NULL))
4075 {
4076 int result;
4077 png_image_read_control display;
4078
4079 memset(&display, 0, (sizeof display));
4080 display.image = image;
4081 display.buffer = buffer;
4082 display.row_stride = row_stride;
4083 display.colormap = colormap;
4084 display.background = background;
4085 display.local_row = NULL;
4086
4087 /* Choose the correct 'end' routine; for the color-map case all the
4088 * setup has already been done.
4089 */
4090 if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0)
4091 result =
4092 png_safe_execute(image, png_image_read_colormap, &display) &&
4093 png_safe_execute(image, png_image_read_colormapped, &display);
4094
4095 else
4096 result =
4097 png_safe_execute(image, png_image_read_direct, &display);
4098
4099 png_image_free(image);
4100 return result;
4101 }
4102
4103 else
4104 return png_image_error(image,
4105 "png_image_finish_read[color-map]: no color-map");
4106 }
4107
4108 else
4109 return png_image_error(image,
4110 "png_image_finish_read: invalid argument");
4111 }
4112
4113 else if (image != NULL)
4114 return png_image_error(image,
4115 "png_image_finish_read: damaged PNG_IMAGE_VERSION");
4116
4117 return 0;
4118 }
4119
4120 #endif /* SIMPLIFIED_READ */
4121 #endif /* READ */
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