pngcrush  1.8.13
About: Pngcrush is an optimizer for PNG (Portable Network Graphics) files.
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pngread.c
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1 
2 /* pngread.c - read a PNG file
3  *
4  * Last changed in libpng 1.6.32 [August 24, 2017]
5  * Copyright (c) 1998-2002,2004,2006-2017 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 #ifndef LIBPNG_UNIFIED
25 #if PNGCRUSH_TIMERS > 4
26 #define PNGCRUSH_TIMER_VOID_API extern void PNGAPI
28 pngcrush_timer_start(unsigned int n);
30 pngcrush_timer_stop(unsigned int n);
31 #endif
32 #endif
33 
34 /* Create a PNG structure for reading, and allocate any memory needed. */
36 png_create_read_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
38 {
39 #ifndef PNG_USER_MEM_SUPPORTED
40  png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
41  error_fn, warn_fn, NULL, NULL, NULL);
42 #else
43  return png_create_read_struct_2(user_png_ver, error_ptr, error_fn,
44  warn_fn, NULL, NULL, NULL);
45 }
46 
47 /* Alternate create PNG structure for reading, and allocate any memory
48  * needed.
49  */
51 png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
52  png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
54 {
55  png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
56  error_fn, warn_fn, mem_ptr, malloc_fn, free_fn);
57 #endif /* USER_MEM */
58 
59  if (png_ptr != NULL)
60  {
61  png_ptr->mode = PNG_IS_READ_STRUCT;
62 
63  /* Added in libpng-1.6.0; this can be used to detect a read structure if
64  * required (it will be zero in a write structure.)
65  */
66 # ifdef PNG_SEQUENTIAL_READ_SUPPORTED
67  png_ptr->IDAT_read_size = PNG_IDAT_READ_SIZE;
68 # endif
69 
70 # ifdef PNG_BENIGN_READ_ERRORS_SUPPORTED
72 
73  /* In stable builds only warn if an application error can be completely
74  * handled.
75  */
76 # if PNG_RELEASE_BUILD
78 # endif
79 # endif
80 
81  /* TODO: delay this, it can be done in png_init_io (if the app doesn't
82  * do it itself) avoiding setting the default function if it is not
83  * required.
84  */
85  png_set_read_fn(png_ptr, NULL, NULL);
86  }
87 
88  return png_ptr;
89 }
90 
91 
92 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
93 /* Read the information before the actual image data. This has been
94  * changed in v0.90 to allow reading a file that already has the magic
95  * bytes read from the stream. You can tell libpng how many bytes have
96  * been read from the beginning of the stream (up to the maximum of 8)
97  * via png_set_sig_bytes(), and we will only check the remaining bytes
98  * here. The application can then have access to the signature bytes we
99  * read if it is determined that this isn't a valid PNG file.
100  */
101 void PNGAPI
103 {
104 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
105  int keep;
106 #endif
107 
108  png_debug(1, "in png_read_info");
109 
110  if (png_ptr == NULL || info_ptr == NULL)
111  return;
112 
113  /* Read and check the PNG file signature. */
114  png_read_sig(png_ptr, info_ptr);
115 
116  for (;;)
117  {
118  png_uint_32 length = png_read_chunk_header(png_ptr);
119  png_uint_32 chunk_name = png_ptr->chunk_name;
120 
121  /* IDAT logic needs to happen here to simplify getting the two flags
122  * right.
123  */
124  if (chunk_name == png_IDAT)
125  {
126  if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
127  png_chunk_error(png_ptr, "Missing IHDR before IDAT");
128 
129  else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
130  (png_ptr->mode & PNG_HAVE_PLTE) == 0)
131  png_chunk_error(png_ptr, "Missing PLTE before IDAT");
132 
133  else if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
134  png_chunk_benign_error(png_ptr, "Too many IDATs found");
135 
136  png_ptr->mode |= PNG_HAVE_IDAT;
137  }
138 
139  else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
140  {
141  png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
142  png_ptr->mode |= PNG_AFTER_IDAT;
143  }
144 
145  /* This should be a binary subdivision search or a hash for
146  * matching the chunk name rather than a linear search.
147  */
148  if (chunk_name == png_IHDR)
149  png_handle_IHDR(png_ptr, info_ptr, length);
150 
151  else if (chunk_name == png_IEND)
152  png_handle_IEND(png_ptr, info_ptr, length);
153 
154 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
155  else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
156  {
157  png_handle_unknown(png_ptr, info_ptr, length, keep);
158 
159  if (chunk_name == png_PLTE)
160  png_ptr->mode |= PNG_HAVE_PLTE;
161 
162  else if (chunk_name == png_IDAT)
163  {
164  png_ptr->idat_size = 0; /* It has been consumed */
165  break;
166  }
167  }
168 #endif
169  else if (chunk_name == png_PLTE)
170  png_handle_PLTE(png_ptr, info_ptr, length);
171 
172  else if (chunk_name == png_IDAT)
173  {
174  png_ptr->idat_size = length;
175  break;
176  }
177 
178 #ifdef PNG_READ_bKGD_SUPPORTED
179  else if (chunk_name == png_bKGD)
180  png_handle_bKGD(png_ptr, info_ptr, length);
181 #endif
182 
183 #ifdef PNG_READ_cHRM_SUPPORTED
184  else if (chunk_name == png_cHRM)
185  png_handle_cHRM(png_ptr, info_ptr, length);
186 #endif
187 
188 #ifdef PNG_READ_eXIf_SUPPORTED
189  else if (chunk_name == png_eXIf)
190  png_handle_eXIf(png_ptr, info_ptr, length);
191 #endif
192 
193 #ifdef PNG_READ_gAMA_SUPPORTED
194  else if (chunk_name == png_gAMA)
195  png_handle_gAMA(png_ptr, info_ptr, length);
196 #endif
197 
198 #ifdef PNG_READ_hIST_SUPPORTED
199  else if (chunk_name == png_hIST)
200  png_handle_hIST(png_ptr, info_ptr, length);
201 #endif
202 
203 #ifdef PNG_READ_oFFs_SUPPORTED
204  else if (chunk_name == png_oFFs)
205  png_handle_oFFs(png_ptr, info_ptr, length);
206 #endif
207 
208 #ifdef PNG_READ_pCAL_SUPPORTED
209  else if (chunk_name == png_pCAL)
210  png_handle_pCAL(png_ptr, info_ptr, length);
211 #endif
212 
213 #ifdef PNG_READ_sCAL_SUPPORTED
214  else if (chunk_name == png_sCAL)
215  png_handle_sCAL(png_ptr, info_ptr, length);
216 #endif
217 
218 #ifdef PNG_READ_pHYs_SUPPORTED
219  else if (chunk_name == png_pHYs)
220  png_handle_pHYs(png_ptr, info_ptr, length);
221 #endif
222 
223 #ifdef PNG_READ_sBIT_SUPPORTED
224  else if (chunk_name == png_sBIT)
225  png_handle_sBIT(png_ptr, info_ptr, length);
226 #endif
227 
228 #ifdef PNG_READ_sRGB_SUPPORTED
229  else if (chunk_name == png_sRGB)
230  png_handle_sRGB(png_ptr, info_ptr, length);
231 #endif
232 
233 #ifdef PNG_READ_iCCP_SUPPORTED
234  else if (chunk_name == png_iCCP)
235  png_handle_iCCP(png_ptr, info_ptr, length);
236 #endif
237 
238 #ifdef PNG_READ_sPLT_SUPPORTED
239  else if (chunk_name == png_sPLT)
240  png_handle_sPLT(png_ptr, info_ptr, length);
241 #endif
242 
243 #ifdef PNG_READ_tEXt_SUPPORTED
244  else if (chunk_name == png_tEXt)
245  png_handle_tEXt(png_ptr, info_ptr, length);
246 #endif
247 
248 #ifdef PNG_READ_tIME_SUPPORTED
249  else if (chunk_name == png_tIME)
250  png_handle_tIME(png_ptr, info_ptr, length);
251 #endif
252 
253 #ifdef PNG_READ_tRNS_SUPPORTED
254  else if (chunk_name == png_tRNS)
255  png_handle_tRNS(png_ptr, info_ptr, length);
256 #endif
257 
258 #ifdef PNG_READ_zTXt_SUPPORTED
259  else if (chunk_name == png_zTXt)
260  png_handle_zTXt(png_ptr, info_ptr, length);
261 #endif
262 
263 #ifdef PNG_READ_iTXt_SUPPORTED
264  else if (chunk_name == png_iTXt)
265  png_handle_iTXt(png_ptr, info_ptr, length);
266 #endif
267 
268  else
269  png_handle_unknown(png_ptr, info_ptr, length,
271  }
272 }
273 #endif /* SEQUENTIAL_READ */
274 
275 /* Optional call to update the users info_ptr structure */
276 void PNGAPI
278 {
279  png_debug(1, "in png_read_update_info");
280 
281  if (png_ptr != NULL)
282  {
283  if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
284  {
285  png_read_start_row(png_ptr);
286 
287 # ifdef PNG_READ_TRANSFORMS_SUPPORTED
288  png_read_transform_info(png_ptr, info_ptr);
289 # else
290  PNG_UNUSED(info_ptr)
291 # endif
292  }
293 
294  /* New in 1.6.0 this avoids the bug of doing the initializations twice */
295  else
296  png_app_error(png_ptr,
297  "png_read_update_info/png_start_read_image: duplicate call");
298  }
299 }
300 
301 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
302 /* Initialize palette, background, etc, after transformations
303  * are set, but before any reading takes place. This allows
304  * the user to obtain a gamma-corrected palette, for example.
305  * If the user doesn't call this, we will do it ourselves.
306  */
307 void PNGAPI
309 {
310  png_debug(1, "in png_start_read_image");
311 
312  if (png_ptr != NULL)
313  {
314  if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
315  png_read_start_row(png_ptr);
316 
317  /* New in 1.6.0 this avoids the bug of doing the initializations twice */
318  else
319  png_app_error(png_ptr,
320  "png_start_read_image/png_read_update_info: duplicate call");
321  }
322 }
323 #endif /* SEQUENTIAL_READ */
324 
325 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
326 #ifdef PNG_MNG_FEATURES_SUPPORTED
327 /* Undoes intrapixel differencing,
328  * NOTE: this is apparently only supported in the 'sequential' reader.
329  */
330 static void
332 {
333  png_debug(1, "in png_do_read_intrapixel");
334 
335  if (
336  (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
337  {
338  int bytes_per_pixel;
339  png_uint_32 row_width = row_info->width;
340 
341  if (row_info->bit_depth == 8)
342  {
343  png_bytep rp;
344  png_uint_32 i;
345 
346  if (row_info->color_type == PNG_COLOR_TYPE_RGB)
347  bytes_per_pixel = 3;
348 
349  else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
350  bytes_per_pixel = 4;
351 
352  else
353  return;
354 
355  for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
356  {
357  *(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff);
358  *(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff);
359  }
360  }
361  else if (row_info->bit_depth == 16)
362  {
363  png_bytep rp;
364  png_uint_32 i;
365 
366  if (row_info->color_type == PNG_COLOR_TYPE_RGB)
367  bytes_per_pixel = 6;
368 
369  else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
370  bytes_per_pixel = 8;
371 
372  else
373  return;
374 
375  for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
376  {
377  png_uint_32 s0 = (png_uint_32)(*(rp ) << 8) | *(rp + 1);
378  png_uint_32 s1 = (png_uint_32)(*(rp + 2) << 8) | *(rp + 3);
379  png_uint_32 s2 = (png_uint_32)(*(rp + 4) << 8) | *(rp + 5);
380  png_uint_32 red = (s0 + s1 + 65536) & 0xffff;
381  png_uint_32 blue = (s2 + s1 + 65536) & 0xffff;
382  *(rp ) = (png_byte)((red >> 8) & 0xff);
383  *(rp + 1) = (png_byte)(red & 0xff);
384  *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
385  *(rp + 5) = (png_byte)(blue & 0xff);
386  }
387  }
388  }
389 }
390 #endif /* MNG_FEATURES */
391 
392 void PNGAPI
394 {
395  png_row_info row_info;
396 
397  if (png_ptr == NULL)
398  return;
399 
400  png_debug2(1, "in png_read_row (row %lu, pass %d)",
401  (unsigned long)png_ptr->row_number, png_ptr->pass);
402 
403  /* png_read_start_row sets the information (in particular iwidth) for this
404  * interlace pass.
405  */
406  if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
407  png_read_start_row(png_ptr);
408 
409  /* 1.5.6: row_info moved out of png_struct to a local here. */
410  row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
411  row_info.color_type = png_ptr->color_type;
412  row_info.bit_depth = png_ptr->bit_depth;
413  row_info.channels = png_ptr->channels;
414  row_info.pixel_depth = png_ptr->pixel_depth;
415  row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
416 
417 #ifdef PNG_WARNINGS_SUPPORTED
418  if (png_ptr->row_number == 0 && png_ptr->pass == 0)
419  {
420  /* Check for transforms that have been set but were defined out */
421 #if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED)
422  if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
423  png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined");
424 #endif
425 
426 #if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED)
427  if ((png_ptr->transformations & PNG_FILLER) != 0)
428  png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined");
429 #endif
430 
431 #if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
432  !defined(PNG_READ_PACKSWAP_SUPPORTED)
433  if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
434  png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined");
435 #endif
436 
437 #if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED)
438  if ((png_ptr->transformations & PNG_PACK) != 0)
439  png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined");
440 #endif
441 
442 #if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED)
443  if ((png_ptr->transformations & PNG_SHIFT) != 0)
444  png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined");
445 #endif
446 
447 #if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED)
448  if ((png_ptr->transformations & PNG_BGR) != 0)
449  png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined");
450 #endif
451 
452 #if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED)
453  if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
454  png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined");
455 #endif
456  }
457 #endif /* WARNINGS */
458 
459 #ifdef PNG_READ_INTERLACING_SUPPORTED
460  /* If interlaced and we do not need a new row, combine row and return.
461  * Notice that the pixels we have from previous rows have been transformed
462  * already; we can only combine like with like (transformed or
463  * untransformed) and, because of the libpng API for interlaced images, this
464  * means we must transform before de-interlacing.
465  */
466  if (png_ptr->interlaced != 0 &&
467  (png_ptr->transformations & PNG_INTERLACE) != 0)
468  {
469 #if PNGCRUSH_TIMERS > 4
471 #endif
472  switch (png_ptr->pass)
473  {
474  case 0:
475  if (png_ptr->row_number & 0x07)
476  {
477  if (dsp_row != NULL)
478  png_combine_row(png_ptr, dsp_row, 1/*display*/);
479  png_read_finish_row(png_ptr);
480  return;
481  }
482  break;
483 
484  case 1:
485  if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
486  {
487  if (dsp_row != NULL)
488  png_combine_row(png_ptr, dsp_row, 1/*display*/);
489 
490  png_read_finish_row(png_ptr);
491  return;
492  }
493  break;
494 
495  case 2:
496  if ((png_ptr->row_number & 0x07) != 4)
497  {
498  if (dsp_row != NULL && (png_ptr->row_number & 4))
499  png_combine_row(png_ptr, dsp_row, 1/*display*/);
500 
501  png_read_finish_row(png_ptr);
502  return;
503  }
504  break;
505 
506  case 3:
507  if ((png_ptr->row_number & 3) || png_ptr->width < 3)
508  {
509  if (dsp_row != NULL)
510  png_combine_row(png_ptr, dsp_row, 1/*display*/);
511 
512  png_read_finish_row(png_ptr);
513  return;
514  }
515  break;
516 
517  case 4:
518  if ((png_ptr->row_number & 3) != 2)
519  {
520  if (dsp_row != NULL && (png_ptr->row_number & 2))
521  png_combine_row(png_ptr, dsp_row, 1/*display*/);
522 
523  png_read_finish_row(png_ptr);
524  return;
525  }
526  break;
527 
528  case 5:
529  if ((png_ptr->row_number & 1) || png_ptr->width < 2)
530  {
531  if (dsp_row != NULL)
532  png_combine_row(png_ptr, dsp_row, 1/*display*/);
533 
534  png_read_finish_row(png_ptr);
535  return;
536  }
537  break;
538 
539  default:
540  case 6:
541  if ((png_ptr->row_number & 1) == 0)
542  {
543  png_read_finish_row(png_ptr);
544  return;
545  }
546  break;
547  }
548 #if PNGCRUSH_TIMERS > 4
550 #endif
551  }
552 #endif
553 
554  if ((png_ptr->mode & PNG_HAVE_IDAT) == 0)
555  png_error(png_ptr, "Invalid attempt to read row data");
556 
557  /* Fill the row with IDAT data: */
558  png_ptr->row_buf[0]=255; /* to force error if no data was found */
559  png_read_IDAT_data(png_ptr, png_ptr->row_buf, row_info.rowbytes + 1);
560 
561 #if PNGCRUSH_TIMERS > 5
562  pngcrush_timer_start(png_ptr->row_buf[0]+5);
563 #endif
564 
565  if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
566  {
567  if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
568  png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
569  png_ptr->prev_row + 1, png_ptr->row_buf[0]);
570  else
571  png_error(png_ptr, "bad adaptive filter value");
572  }
573 #if PNGCRUSH_TIMERS > 5
574  pngcrush_timer_stop(png_ptr->row_buf[0]+5);
575 #endif
576 
577  /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
578  * 1.5.6, while the buffer really is this big in current versions of libpng
579  * it may not be in the future, so this was changed just to copy the
580  * interlaced count:
581  */
582  memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
583 
584 #ifdef PNG_MNG_FEATURES_SUPPORTED
585  if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
586  (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
587  {
588  /* Intrapixel differencing */
589  png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1);
590  }
591 #endif
592 
593 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
594  if (png_ptr->transformations)
595  png_do_read_transformations(png_ptr, &row_info);
596 #endif
597 
598  /* The transformed pixel depth should match the depth now in row_info. */
599  if (png_ptr->transformed_pixel_depth == 0)
600  {
601  png_ptr->transformed_pixel_depth = row_info.pixel_depth;
602  if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
603  png_error(png_ptr, "sequential row overflow");
604  }
605 
606  else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
607  png_error(png_ptr, "internal sequential row size calculation error");
608 
609 #ifdef PNG_READ_INTERLACING_SUPPORTED
610  /* Expand interlaced rows to full size */
611  if (png_ptr->interlaced != 0 &&
612  (png_ptr->transformations & PNG_INTERLACE) != 0)
613  {
614  if (png_ptr->pass < 6)
615  png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
616  png_ptr->transformations);
617 
618  if (dsp_row != NULL)
619  png_combine_row(png_ptr, dsp_row, 1/*display*/);
620 
621  if (row != NULL)
622  png_combine_row(png_ptr, row, 0/*row*/);
623  }
624 
625  else
626 #endif
627  {
628  if (row != NULL)
629  png_combine_row(png_ptr, row, -1/*ignored*/);
630 
631  if (dsp_row != NULL)
632  png_combine_row(png_ptr, dsp_row, -1/*ignored*/);
633  }
634  png_read_finish_row(png_ptr);
635 
636  if (png_ptr->read_row_fn != NULL)
637  (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
638 
639 }
640 #endif /* SEQUENTIAL_READ */
641 
642 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
643 /* Read one or more rows of image data. If the image is interlaced,
644  * and png_set_interlace_handling() has been called, the rows need to
645  * contain the contents of the rows from the previous pass. If the
646  * image has alpha or transparency, and png_handle_alpha()[*] has been
647  * called, the rows contents must be initialized to the contents of the
648  * screen.
649  *
650  * "row" holds the actual image, and pixels are placed in it
651  * as they arrive. If the image is displayed after each pass, it will
652  * appear to "sparkle" in. "display_row" can be used to display a
653  * "chunky" progressive image, with finer detail added as it becomes
654  * available. If you do not want this "chunky" display, you may pass
655  * NULL for display_row. If you do not want the sparkle display, and
656  * you have not called png_handle_alpha(), you may pass NULL for rows.
657  * If you have called png_handle_alpha(), and the image has either an
658  * alpha channel or a transparency chunk, you must provide a buffer for
659  * rows. In this case, you do not have to provide a display_row buffer
660  * also, but you may. If the image is not interlaced, or if you have
661  * not called png_set_interlace_handling(), the display_row buffer will
662  * be ignored, so pass NULL to it.
663  *
664  * [*] png_handle_alpha() does not exist yet, as of this version of libpng
665  */
666 
667 void PNGAPI
669  png_bytepp display_row, png_uint_32 num_rows)
670 {
671  png_uint_32 i;
672  png_bytepp rp;
673  png_bytepp dp;
674 
675  png_debug(1, "in png_read_rows");
676 
677  if (png_ptr == NULL)
678  return;
679 
680  rp = row;
681  dp = display_row;
682  if (rp != NULL && dp != NULL)
683  for (i = 0; i < num_rows; i++)
684  {
685  png_bytep rptr = *rp++;
686  png_bytep dptr = *dp++;
687 
688  png_read_row(png_ptr, rptr, dptr);
689  }
690 
691  else if (rp != NULL)
692  for (i = 0; i < num_rows; i++)
693  {
694  png_bytep rptr = *rp;
695  png_read_row(png_ptr, rptr, NULL);
696  rp++;
697  }
698 
699  else if (dp != NULL)
700  for (i = 0; i < num_rows; i++)
701  {
702  png_bytep dptr = *dp;
703  png_read_row(png_ptr, NULL, dptr);
704  dp++;
705  }
706 }
707 #endif /* SEQUENTIAL_READ */
708 
709 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
710 /* Read the entire image. If the image has an alpha channel or a tRNS
711  * chunk, and you have called png_handle_alpha()[*], you will need to
712  * initialize the image to the current image that PNG will be overlaying.
713  * We set the num_rows again here, in case it was incorrectly set in
714  * png_read_start_row() by a call to png_read_update_info() or
715  * png_start_read_image() if png_set_interlace_handling() wasn't called
716  * prior to either of these functions like it should have been. You can
717  * only call this function once. If you desire to have an image for
718  * each pass of a interlaced image, use png_read_rows() instead.
719  *
720  * [*] png_handle_alpha() does not exist yet, as of this version of libpng
721  */
722 void PNGAPI
724 {
725  png_uint_32 i, image_height;
726  int pass, j;
727  png_bytepp rp;
728 
729  png_debug(1, "in png_read_image");
730 
731  if (png_ptr == NULL)
732  return;
733 
734 #ifdef PNG_READ_INTERLACING_SUPPORTED
735  if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
736  {
737  pass = png_set_interlace_handling(png_ptr);
738  /* And make sure transforms are initialized. */
739  png_start_read_image(png_ptr);
740  }
741  else
742  {
743  if (png_ptr->interlaced != 0 &&
744  (png_ptr->transformations & PNG_INTERLACE) == 0)
745  {
746  /* Caller called png_start_read_image or png_read_update_info without
747  * first turning on the PNG_INTERLACE transform. We can fix this here,
748  * but the caller should do it!
749  */
750  png_warning(png_ptr, "Interlace handling should be turned on when "
751  "using png_read_image");
752  /* Make sure this is set correctly */
753  png_ptr->num_rows = png_ptr->height;
754  }
755 
756  /* Obtain the pass number, which also turns on the PNG_INTERLACE flag in
757  * the above error case.
758  */
759  pass = png_set_interlace_handling(png_ptr);
760  }
761 #else
762  if (png_ptr->interlaced)
763  png_error(png_ptr,
764  "Cannot read interlaced image -- interlace handler disabled");
765 
766  pass = 1;
767 #endif
768 
769  image_height=png_ptr->height;
770 
771  for (j = 0; j < pass; j++)
772  {
773  rp = image;
774  for (i = 0; i < image_height; i++)
775  {
776  png_read_row(png_ptr, *rp, NULL);
777  rp++;
778  }
779  }
780 }
781 #endif /* SEQUENTIAL_READ */
782 
783 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
784 /* Read the end of the PNG file. Will not read past the end of the
785  * file, will verify the end is accurate, and will read any comments
786  * or time information at the end of the file, if info is not NULL.
787  */
788 void PNGAPI
790 {
791 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
792  int keep;
793 #endif
794 
795  png_debug(1, "in png_read_end");
796 
797  if (png_ptr == NULL)
798  return;
799 
800  /* If png_read_end is called in the middle of reading the rows there may
801  * still be pending IDAT data and an owned zstream. Deal with this here.
802  */
803 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
804  if (png_chunk_unknown_handling(png_ptr, png_IDAT) == 0)
805 #endif
806  png_read_finish_IDAT(png_ptr);
807 
808 #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
809  /* Report invalid palette index; added at libng-1.5.10 */
810  if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
811  png_ptr->num_palette_max > png_ptr->num_palette)
812  png_benign_error(png_ptr, "Read palette index exceeding num_palette");
813 #endif
814 
815  do
816  {
817  png_uint_32 length = png_read_chunk_header(png_ptr);
818  png_uint_32 chunk_name = png_ptr->chunk_name;
819 
820  if (chunk_name != png_IDAT)
821  png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
822 
823  if (chunk_name == png_IEND)
824  png_handle_IEND(png_ptr, info_ptr, length);
825 
826  else if (chunk_name == png_IHDR)
827  png_handle_IHDR(png_ptr, info_ptr, length);
828 
829  else if (info_ptr == NULL)
830  png_crc_finish(png_ptr, length);
831 
832 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
833  else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
834  {
835  if (chunk_name == png_IDAT)
836  {
837  if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
838  || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
839  png_benign_error(png_ptr, ".Too many IDATs found");
840  }
841  png_handle_unknown(png_ptr, info_ptr, length, keep);
842  if (chunk_name == png_PLTE)
843  png_ptr->mode |= PNG_HAVE_PLTE;
844  }
845 #endif
846 
847  else if (chunk_name == png_IDAT)
848  {
849  /* Zero length IDATs are legal after the last IDAT has been
850  * read, but not after other chunks have been read. 1.6 does not
851  * always read all the deflate data; specifically it cannot be relied
852  * upon to read the Adler32 at the end. If it doesn't ignore IDAT
853  * chunks which are longer than zero as well:
854  */
855  if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
856  || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
857  png_benign_error(png_ptr, "..Too many IDATs found");
858 
859  png_crc_finish(png_ptr, length);
860  }
861  else if (chunk_name == png_PLTE)
862  png_handle_PLTE(png_ptr, info_ptr, length);
863 
864 #ifdef PNG_READ_bKGD_SUPPORTED
865  else if (chunk_name == png_bKGD)
866  png_handle_bKGD(png_ptr, info_ptr, length);
867 #endif
868 
869 #ifdef PNG_READ_cHRM_SUPPORTED
870  else if (chunk_name == png_cHRM)
871  png_handle_cHRM(png_ptr, info_ptr, length);
872 #endif
873 
874 #ifdef PNG_READ_eXIf_SUPPORTED
875  else if (chunk_name == png_eXIf)
876  png_handle_eXIf(png_ptr, info_ptr, length);
877 #endif
878 
879 #ifdef PNG_READ_gAMA_SUPPORTED
880  else if (chunk_name == png_gAMA)
881  png_handle_gAMA(png_ptr, info_ptr, length);
882 #endif
883 
884 #ifdef PNG_READ_hIST_SUPPORTED
885  else if (chunk_name == png_hIST)
886  png_handle_hIST(png_ptr, info_ptr, length);
887 #endif
888 
889 #ifdef PNG_READ_oFFs_SUPPORTED
890  else if (chunk_name == png_oFFs)
891  png_handle_oFFs(png_ptr, info_ptr, length);
892 #endif
893 
894 #ifdef PNG_READ_pCAL_SUPPORTED
895  else if (chunk_name == png_pCAL)
896  png_handle_pCAL(png_ptr, info_ptr, length);
897 #endif
898 
899 #ifdef PNG_READ_sCAL_SUPPORTED
900  else if (chunk_name == png_sCAL)
901  png_handle_sCAL(png_ptr, info_ptr, length);
902 #endif
903 
904 #ifdef PNG_READ_pHYs_SUPPORTED
905  else if (chunk_name == png_pHYs)
906  png_handle_pHYs(png_ptr, info_ptr, length);
907 #endif
908 
909 #ifdef PNG_READ_sBIT_SUPPORTED
910  else if (chunk_name == png_sBIT)
911  png_handle_sBIT(png_ptr, info_ptr, length);
912 #endif
913 
914 #ifdef PNG_READ_sRGB_SUPPORTED
915  else if (chunk_name == png_sRGB)
916  png_handle_sRGB(png_ptr, info_ptr, length);
917 #endif
918 
919 #ifdef PNG_READ_iCCP_SUPPORTED
920  else if (chunk_name == png_iCCP)
921  png_handle_iCCP(png_ptr, info_ptr, length);
922 #endif
923 
924 #ifdef PNG_READ_sPLT_SUPPORTED
925  else if (chunk_name == png_sPLT)
926  png_handle_sPLT(png_ptr, info_ptr, length);
927 #endif
928 
929 #ifdef PNG_READ_tEXt_SUPPORTED
930  else if (chunk_name == png_tEXt)
931  png_handle_tEXt(png_ptr, info_ptr, length);
932 #endif
933 
934 #ifdef PNG_READ_tIME_SUPPORTED
935  else if (chunk_name == png_tIME)
936  png_handle_tIME(png_ptr, info_ptr, length);
937 #endif
938 
939 #ifdef PNG_READ_tRNS_SUPPORTED
940  else if (chunk_name == png_tRNS)
941  png_handle_tRNS(png_ptr, info_ptr, length);
942 #endif
943 
944 #ifdef PNG_READ_zTXt_SUPPORTED
945  else if (chunk_name == png_zTXt)
946  png_handle_zTXt(png_ptr, info_ptr, length);
947 #endif
948 
949 #ifdef PNG_READ_iTXt_SUPPORTED
950  else if (chunk_name == png_iTXt)
951  png_handle_iTXt(png_ptr, info_ptr, length);
952 #endif
953 
954  else
955  png_handle_unknown(png_ptr, info_ptr, length,
957  } while ((png_ptr->mode & PNG_HAVE_IEND) == 0);
958 }
959 #endif /* SEQUENTIAL_READ */
960 
961 /* Free all memory used in the read struct */
962 static void
964 {
965  png_debug(1, "in png_read_destroy");
966 
967 #ifdef PNG_READ_GAMMA_SUPPORTED
968  png_destroy_gamma_table(png_ptr);
969 #endif
970 
971  png_free(png_ptr, png_ptr->big_row_buf);
972  png_ptr->big_row_buf = NULL;
973  png_free(png_ptr, png_ptr->big_prev_row);
974  png_ptr->big_prev_row = NULL;
975  png_free(png_ptr, png_ptr->read_buffer);
976  png_ptr->read_buffer = NULL;
977 
978 #ifdef PNG_READ_QUANTIZE_SUPPORTED
979  png_free(png_ptr, png_ptr->palette_lookup);
980  png_ptr->palette_lookup = NULL;
981  png_free(png_ptr, png_ptr->quantize_index);
982  png_ptr->quantize_index = NULL;
983 #endif
984 
985  if ((png_ptr->free_me & PNG_FREE_PLTE) != 0)
986  {
987  png_zfree(png_ptr, png_ptr->palette);
988  png_ptr->palette = NULL;
989  }
990  png_ptr->free_me &= ~PNG_FREE_PLTE;
991 
992 #if defined(PNG_tRNS_SUPPORTED) || \
993  defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
994  if ((png_ptr->free_me & PNG_FREE_TRNS) != 0)
995  {
996  png_free(png_ptr, png_ptr->trans_alpha);
997  png_ptr->trans_alpha = NULL;
998  }
999  png_ptr->free_me &= ~PNG_FREE_TRNS;
1000 #endif
1001 
1002  inflateEnd(&png_ptr->zstream);
1003 
1004 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
1005  png_free(png_ptr, png_ptr->save_buffer);
1006  png_ptr->save_buffer = NULL;
1007 #endif
1008 
1009 #if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) && \
1010  defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
1011  png_free(png_ptr, png_ptr->unknown_chunk.data);
1012  png_ptr->unknown_chunk.data = NULL;
1013 #endif
1014 
1015 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
1016  png_free(png_ptr, png_ptr->chunk_list);
1017  png_ptr->chunk_list = NULL;
1018 #endif
1019 
1020  /* NOTE: the 'setjmp' buffer may still be allocated and the memory and error
1021  * callbacks are still set at this point. They are required to complete the
1022  * destruction of the png_struct itself.
1023  */
1024 }
1025 
1026 /* Free all memory used by the read */
1027 void PNGAPI
1029  png_infopp end_info_ptr_ptr)
1030 {
1031  png_structrp png_ptr = NULL;
1032 
1033  png_debug(1, "in png_destroy_read_struct");
1034 
1035  if (png_ptr_ptr != NULL)
1036  png_ptr = *png_ptr_ptr;
1037 
1038  if (png_ptr == NULL)
1039  return;
1040 
1041  /* libpng 1.6.0: use the API to destroy info structs to ensure consistent
1042  * behavior. Prior to 1.6.0 libpng did extra 'info' destruction in this API.
1043  * The extra was, apparently, unnecessary yet this hides memory leak bugs.
1044  */
1045  png_destroy_info_struct(png_ptr, end_info_ptr_ptr);
1046  png_destroy_info_struct(png_ptr, info_ptr_ptr);
1047 
1048  *png_ptr_ptr = NULL;
1049  png_read_destroy(png_ptr);
1050  png_destroy_png_struct(png_ptr);
1051 }
1052 
1053 void PNGAPI
1055 {
1056  if (png_ptr == NULL)
1057  return;
1058 
1059  png_ptr->read_row_fn = read_row_fn;
1060 }
1061 
1062 
1063 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1064 #ifdef PNG_INFO_IMAGE_SUPPORTED
1065 void PNGAPI
1067  int transforms, voidp params)
1068 {
1069  if (png_ptr == NULL || info_ptr == NULL)
1070  return;
1071 
1072  /* png_read_info() gives us all of the information from the
1073  * PNG file before the first IDAT (image data chunk).
1074  */
1075  png_read_info(png_ptr, info_ptr);
1076  if (info_ptr->height > PNG_UINT_32_MAX/(sizeof (png_bytep)))
1077  png_error(png_ptr, "Image is too high to process with png_read_png()");
1078 
1079  /* -------------- image transformations start here ------------------- */
1080  /* libpng 1.6.10: add code to cause a png_app_error if a selected TRANSFORM
1081  * is not implemented. This will only happen in de-configured (non-default)
1082  * libpng builds. The results can be unexpected - png_read_png may return
1083  * short or mal-formed rows because the transform is skipped.
1084  */
1085 
1086  /* Tell libpng to strip 16-bit/color files down to 8 bits per color.
1087  */
1088  if ((transforms & PNG_TRANSFORM_SCALE_16) != 0)
1089  /* Added at libpng-1.5.4. "strip_16" produces the same result that it
1090  * did in earlier versions, while "scale_16" is now more accurate.
1091  */
1092 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1093  png_set_scale_16(png_ptr);
1094 #else
1095  png_app_error(png_ptr, "PNG_TRANSFORM_SCALE_16 not supported");
1096 #endif
1097 
1098  /* If both SCALE and STRIP are required pngrtran will effectively cancel the
1099  * latter by doing SCALE first. This is ok and allows apps not to check for
1100  * which is supported to get the right answer.
1101  */
1102  if ((transforms & PNG_TRANSFORM_STRIP_16) != 0)
1103 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1104  png_set_strip_16(png_ptr);
1105 #else
1106  png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_16 not supported");
1107 #endif
1108 
1109  /* Strip alpha bytes from the input data without combining with
1110  * the background (not recommended).
1111  */
1112  if ((transforms & PNG_TRANSFORM_STRIP_ALPHA) != 0)
1113 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1114  png_set_strip_alpha(png_ptr);
1115 #else
1116  png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_ALPHA not supported");
1117 #endif
1118 
1119  /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single
1120  * byte into separate bytes (useful for paletted and grayscale images).
1121  */
1122  if ((transforms & PNG_TRANSFORM_PACKING) != 0)
1123 #ifdef PNG_READ_PACK_SUPPORTED
1124  png_set_packing(png_ptr);
1125 #else
1126  png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported");
1127 #endif
1128 
1129  /* Change the order of packed pixels to least significant bit first
1130  * (not useful if you are using png_set_packing).
1131  */
1132  if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0)
1133 #ifdef PNG_READ_PACKSWAP_SUPPORTED
1134  png_set_packswap(png_ptr);
1135 #else
1136  png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported");
1137 #endif
1138 
1139  /* Expand paletted colors into true RGB triplets
1140  * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel
1141  * Expand paletted or RGB images with transparency to full alpha
1142  * channels so the data will be available as RGBA quartets.
1143  */
1144  if ((transforms & PNG_TRANSFORM_EXPAND) != 0)
1145 #ifdef PNG_READ_EXPAND_SUPPORTED
1146  png_set_expand(png_ptr);
1147 #else
1148  png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND not supported");
1149 #endif
1150 
1151  /* We don't handle background color or gamma transformation or quantizing.
1152  */
1153 
1154  /* Invert monochrome files to have 0 as white and 1 as black
1155  */
1156  if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0)
1157 #ifdef PNG_READ_INVERT_SUPPORTED
1158  png_set_invert_mono(png_ptr);
1159 #else
1160  png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
1161 #endif
1162 
1163  /* If you want to shift the pixel values from the range [0,255] or
1164  * [0,65535] to the original [0,7] or [0,31], or whatever range the
1165  * colors were originally in:
1166  */
1167  if ((transforms & PNG_TRANSFORM_SHIFT) != 0)
1168 #ifdef PNG_READ_SHIFT_SUPPORTED
1169  if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
1170  png_set_shift(png_ptr, &info_ptr->sig_bit);
1171 #else
1172  png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
1173 #endif
1174 
1175  /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
1176  if ((transforms & PNG_TRANSFORM_BGR) != 0)
1177 #ifdef PNG_READ_BGR_SUPPORTED
1178  png_set_bgr(png_ptr);
1179 #else
1180  png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported");
1181 #endif
1182 
1183  /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
1184  if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0)
1185 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
1186  png_set_swap_alpha(png_ptr);
1187 #else
1188  png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported");
1189 #endif
1190 
1191  /* Swap bytes of 16-bit files to least significant byte first */
1192  if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0)
1193 #ifdef PNG_READ_SWAP_SUPPORTED
1194  png_set_swap(png_ptr);
1195 #else
1196  png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
1197 #endif
1198 
1199 /* Added at libpng-1.2.41 */
1200  /* Invert the alpha channel from opacity to transparency */
1201  if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0)
1202 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1203  png_set_invert_alpha(png_ptr);
1204 #else
1205  png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported");
1206 #endif
1207 
1208 /* Added at libpng-1.2.41 */
1209  /* Expand grayscale image to RGB */
1210  if ((transforms & PNG_TRANSFORM_GRAY_TO_RGB) != 0)
1211 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1212  png_set_gray_to_rgb(png_ptr);
1213 #else
1214  png_app_error(png_ptr, "PNG_TRANSFORM_GRAY_TO_RGB not supported");
1215 #endif
1216 
1217 /* Added at libpng-1.5.4 */
1218  if ((transforms & PNG_TRANSFORM_EXPAND_16) != 0)
1219 #ifdef PNG_READ_EXPAND_16_SUPPORTED
1220  png_set_expand_16(png_ptr);
1221 #else
1222  png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND_16 not supported");
1223 #endif
1224 
1225  /* We don't handle adding filler bytes */
1226 
1227  /* We use png_read_image and rely on that for interlace handling, but we also
1228  * call png_read_update_info therefore must turn on interlace handling now:
1229  */
1230  (void)png_set_interlace_handling(png_ptr);
1231 
1232  /* Optional call to gamma correct and add the background to the palette
1233  * and update info structure. REQUIRED if you are expecting libpng to
1234  * update the palette for you (i.e., you selected such a transform above).
1235  */
1236  png_read_update_info(png_ptr, info_ptr);
1237 
1238  /* -------------- image transformations end here ------------------- */
1239 
1240  png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);
1241  if (info_ptr->row_pointers == NULL)
1242  {
1243  png_uint_32 iptr;
1244 
1245  info_ptr->row_pointers = png_voidcast(png_bytepp, png_malloc(png_ptr,
1246  info_ptr->height * (sizeof (png_bytep))));
1247 
1248  for (iptr=0; iptr<info_ptr->height; iptr++)
1249  info_ptr->row_pointers[iptr] = NULL;
1250 
1251  info_ptr->free_me |= PNG_FREE_ROWS;
1252 
1253  for (iptr = 0; iptr < info_ptr->height; iptr++)
1254  info_ptr->row_pointers[iptr] = png_voidcast(png_bytep,
1255  png_malloc(png_ptr, info_ptr->rowbytes));
1256  }
1257 
1258  png_read_image(png_ptr, info_ptr->row_pointers);
1259  info_ptr->valid |= PNG_INFO_IDAT;
1260 
1261  /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
1262  png_read_end(png_ptr, info_ptr);
1263 
1264  PNG_UNUSED(params)
1265 }
1266 #endif /* INFO_IMAGE */
1267 #endif /* SEQUENTIAL_READ */
1268 
1269 #ifdef PNG_SIMPLIFIED_READ_SUPPORTED
1270 /* SIMPLIFIED READ
1271  *
1272  * This code currently relies on the sequential reader, though it could easily
1273  * be made to work with the progressive one.
1274  */
1275 /* Arguments to png_image_finish_read: */
1276 
1277 /* Encoding of PNG data (used by the color-map code) */
1278 # define P_NOTSET 0 /* File encoding not yet known */
1279 # define P_sRGB 1 /* 8-bit encoded to sRGB gamma */
1280 # define P_LINEAR 2 /* 16-bit linear: not encoded, NOT pre-multiplied! */
1281 # define P_FILE 3 /* 8-bit encoded to file gamma, not sRGB or linear */
1282 # define P_LINEAR8 4 /* 8-bit linear: only from a file value */
1283 
1284 /* Color-map processing: after libpng has run on the PNG image further
1285  * processing may be needed to convert the data to color-map indices.
1286  */
1287 #define PNG_CMAP_NONE 0
1288 #define PNG_CMAP_GA 1 /* Process GA data to a color-map with alpha */
1289 #define PNG_CMAP_TRANS 2 /* Process GA data to a background index */
1290 #define PNG_CMAP_RGB 3 /* Process RGB data */
1291 #define PNG_CMAP_RGB_ALPHA 4 /* Process RGBA data */
1292 
1293 /* The following document where the background is for each processing case. */
1294 #define PNG_CMAP_NONE_BACKGROUND 256
1295 #define PNG_CMAP_GA_BACKGROUND 231
1296 #define PNG_CMAP_TRANS_BACKGROUND 254
1297 #define PNG_CMAP_RGB_BACKGROUND 256
1298 #define PNG_CMAP_RGB_ALPHA_BACKGROUND 216
1299 
1300 typedef struct
1301 {
1302  /* Arguments: */
1303  png_imagep image;
1305  png_int_32 row_stride;
1308  /* Local variables: */
1311  ptrdiff_t row_bytes; /* step between rows */
1312  int file_encoding; /* E_ values above */
1313  png_fixed_point gamma_to_linear; /* For P_FILE, reciprocal of gamma */
1314  int colormap_processing; /* PNG_CMAP_ values above */
1316 
1317 /* Do all the *safe* initialization - 'safe' means that png_error won't be
1318  * called, so setting up the jmp_buf is not required. This means that anything
1319  * called from here must *not* call png_malloc - it has to call png_malloc_warn
1320  * instead so that control is returned safely back to this routine.
1321  */
1322 static int
1323 png_image_read_init(png_imagep image)
1324 {
1325  if (image->opaque == NULL)
1326  {
1329 
1330  /* And set the rest of the structure to NULL to ensure that the various
1331  * fields are consistent.
1332  */
1333  memset(image, 0, (sizeof *image));
1334  image->version = PNG_IMAGE_VERSION;
1335 
1336  if (png_ptr != NULL)
1337  {
1338  png_infop info_ptr = png_create_info_struct(png_ptr);
1339 
1340  if (info_ptr != NULL)
1341  {
1342  png_controlp control = png_voidcast(png_controlp,
1343  png_malloc_warn(png_ptr, (sizeof *control)));
1344 
1345  if (control != NULL)
1346  {
1347  memset(control, 0, (sizeof *control));
1348 
1349  control->png_ptr = png_ptr;
1350  control->info_ptr = info_ptr;
1351  control->for_write = 0;
1352 
1353  image->opaque = control;
1354  return 1;
1355  }
1356 
1357  /* Error clean up */
1358  png_destroy_info_struct(png_ptr, &info_ptr);
1359  }
1360 
1361  png_destroy_read_struct(&png_ptr, NULL, NULL);
1362  }
1363 
1364  return png_image_error(image, "png_image_read: out of memory");
1365  }
1366 
1367  return png_image_error(image, "png_image_read: opaque pointer not NULL");
1368 }
1369 
1370 /* Utility to find the base format of a PNG file from a png_struct. */
1371 static png_uint_32
1373 {
1374  png_uint_32 format = 0;
1375 
1376  if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
1377  format |= PNG_FORMAT_FLAG_COLOR;
1378 
1379  if ((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
1380  format |= PNG_FORMAT_FLAG_ALPHA;
1381 
1382  /* Use png_ptr here, not info_ptr, because by examination png_handle_tRNS
1383  * sets the png_struct fields; that's all we are interested in here. The
1384  * precise interaction with an app call to png_set_tRNS and PNG file reading
1385  * is unclear.
1386  */
1387  else if (png_ptr->num_trans > 0)
1388  format |= PNG_FORMAT_FLAG_ALPHA;
1389 
1390  if (png_ptr->bit_depth == 16)
1391  format |= PNG_FORMAT_FLAG_LINEAR;
1392 
1393  if ((png_ptr->color_type & PNG_COLOR_MASK_PALETTE) != 0)
1394  format |= PNG_FORMAT_FLAG_COLORMAP;
1395 
1396  return format;
1397 }
1398 
1399 /* Is the given gamma significantly different from sRGB? The test is the same
1400  * one used in pngrtran.c when deciding whether to do gamma correction. The
1401  * arithmetic optimizes the division by using the fact that the inverse of the
1402  * file sRGB gamma is 2.2
1403  */
1404 static int
1406 {
1407  if (g < PNG_FP_1)
1408  {
1409  /* An uninitialized gamma is assumed to be sRGB for the simplified API. */
1410  if (g == 0)
1411  return 0;
1412 
1413  return png_gamma_significant((g * 11 + 2)/5 /* i.e. *2.2, rounded */);
1414  }
1415 
1416  return 1;
1417 }
1418 
1419 /* Do the main body of a 'png_image_begin_read' function; read the PNG file
1420  * header and fill in all the information. This is executed in a safe context,
1421  * unlike the init routine above.
1422  */
1423 static int
1425 {
1426  png_imagep image = png_voidcast(png_imagep, argument);
1427  png_structrp png_ptr = image->opaque->png_ptr;
1428  png_inforp info_ptr = image->opaque->info_ptr;
1429 
1430 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
1431  png_set_benign_errors(png_ptr, 1/*warn*/);
1432 #endif
1433  png_read_info(png_ptr, info_ptr);
1434 
1435  /* Do this the fast way; just read directly out of png_struct. */
1436  image->width = png_ptr->width;
1437  image->height = png_ptr->height;
1438 
1439  {
1440  png_uint_32 format = png_image_format(png_ptr);
1441 
1442  image->format = format;
1443 
1444 #ifdef PNG_COLORSPACE_SUPPORTED
1445  /* Does the colorspace match sRGB? If there is no color endpoint
1446  * (colorant) information assume yes, otherwise require the
1447  * 'ENDPOINTS_MATCHP_sRGB' colorspace flag to have been set. If the
1448  * colorspace has been determined to be invalid ignore it.
1449  */
1450  if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && ((png_ptr->colorspace.flags
1451  & (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB|
1452  PNG_COLORSPACE_INVALID)) == PNG_COLORSPACE_HAVE_ENDPOINTS))
1453  image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB;
1454 #endif
1455  }
1456 
1457  /* We need the maximum number of entries regardless of the format the
1458  * application sets here.
1459  */
1460  {
1461  png_uint_32 cmap_entries;
1462 
1463  switch (png_ptr->color_type)
1464  {
1465  case PNG_COLOR_TYPE_GRAY:
1466  cmap_entries = 1U << png_ptr->bit_depth;
1467  break;
1468 
1470  cmap_entries = (png_uint_32)png_ptr->num_palette;
1471  break;
1472 
1473  default:
1474  cmap_entries = 256;
1475  break;
1476  }
1477 
1478  if (cmap_entries > 256)
1479  cmap_entries = 256;
1480 
1481  image->colormap_entries = cmap_entries;
1482  }
1483 
1484  return 1;
1485 }
1486 
1487 #ifdef PNG_STDIO_SUPPORTED
1488 int PNGAPI
1489 png_image_begin_read_from_stdio(png_imagep image, FILE* file)
1490 {
1491  if (image != NULL && image->version == PNG_IMAGE_VERSION)
1492  {
1493  if (file != NULL)
1494  {
1495  if (png_image_read_init(image) != 0)
1496  {
1497  /* This is slightly evil, but png_init_io doesn't do anything other
1498  * than this and we haven't changed the standard IO functions so
1499  * this saves a 'safe' function.
1500  */
1501  image->opaque->png_ptr->io_ptr = file;
1502  return png_safe_execute(image, png_image_read_header, image);
1503  }
1504  }
1505 
1506  else
1507  return png_image_error(image,
1508  "png_image_begin_read_from_stdio: invalid argument");
1509  }
1510 
1511  else if (image != NULL)
1512  return png_image_error(image,
1513  "png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION");
1514 
1515  return 0;
1516 }
1517 
1518 int PNGAPI
1519 png_image_begin_read_from_file(png_imagep image, const char *file_name)
1520 {
1521  if (image != NULL && image->version == PNG_IMAGE_VERSION)
1522  {
1523  if (file_name != NULL)
1524  {
1525  FILE *fp = fopen(file_name, "rb");
1526 
1527  if (fp != NULL)
1528  {
1529  if (png_image_read_init(image) != 0)
1530  {
1531  image->opaque->png_ptr->io_ptr = fp;
1532  image->opaque->owned_file = 1;
1533  return png_safe_execute(image, png_image_read_header, image);
1534  }
1535 
1536  /* Clean up: just the opened file. */
1537  (void)fclose(fp);
1538  }
1539 
1540  else
1541  return png_image_error(image, strerror(errno));
1542  }
1543 
1544  else
1545  return png_image_error(image,
1546  "png_image_begin_read_from_file: invalid argument");
1547  }
1548 
1549  else if (image != NULL)
1550  return png_image_error(image,
1551  "png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION");
1552 
1553  return 0;
1554 }
1555 #endif /* STDIO */
1556 
1557 static void PNGCBAPI
1559 {
1560  if (png_ptr != NULL)
1561  {
1562  png_imagep image = png_voidcast(png_imagep, png_ptr->io_ptr);
1563  if (image != NULL)
1564  {
1565  png_controlp cp = image->opaque;
1566  if (cp != NULL)
1567  {
1568  png_const_bytep memory = cp->memory;
1569  png_size_t size = cp->size;
1570 
1571  if (memory != NULL && size >= need)
1572  {
1573  memcpy(out, memory, need);
1574  cp->memory = memory + need;
1575  cp->size = size - need;
1576  return;
1577  }
1578 
1579  png_error(png_ptr, "read beyond end of data");
1580  }
1581  }
1582 
1583  png_error(png_ptr, "invalid memory read");
1584  }
1585 }
1586 
1588  png_const_voidp memory, png_size_t size)
1589 {
1590  if (image != NULL && image->version == PNG_IMAGE_VERSION)
1591  {
1592  if (memory != NULL && size > 0)
1593  {
1594  if (png_image_read_init(image) != 0)
1595  {
1596  /* Now set the IO functions to read from the memory buffer and
1597  * store it into io_ptr. Again do this in-place to avoid calling a
1598  * libpng function that requires error handling.
1599  */
1600  image->opaque->memory = png_voidcast(png_const_bytep, memory);
1601  image->opaque->size = size;
1602  image->opaque->png_ptr->io_ptr = image;
1603  image->opaque->png_ptr->read_data_fn = png_image_memory_read;
1604 
1605  return png_safe_execute(image, png_image_read_header, image);
1606  }
1607  }
1608 
1609  else
1610  return png_image_error(image,
1611  "png_image_begin_read_from_memory: invalid argument");
1612  }
1613 
1614  else if (image != NULL)
1615  return png_image_error(image,
1616  "png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION");
1617 
1618  return 0;
1619 }
1620 
1621 /* Utility function to skip chunks that are not used by the simplified image
1622  * read functions and an appropriate macro to call it.
1623  */
1624 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
1625 static void
1627 {
1628  /* Prepare the reader to ignore all recognized chunks whose data will not
1629  * be used, i.e., all chunks recognized by libpng except for those
1630  * involved in basic image reading:
1631  *
1632  * IHDR, PLTE, IDAT, IEND
1633  *
1634  * Or image data handling:
1635  *
1636  * tRNS, bKGD, gAMA, cHRM, sRGB, [iCCP] and sBIT.
1637  *
1638  * This provides a small performance improvement and eliminates any
1639  * potential vulnerability to security problems in the unused chunks.
1640  *
1641  * At present the iCCP chunk data isn't used, so iCCP chunk can be ignored
1642  * too. This allows the simplified API to be compiled without iCCP support,
1643  * however if the support is there the chunk is still checked to detect
1644  * errors (which are unfortunately quite common.)
1645  */
1646  {
1647  static PNG_CONST png_byte chunks_to_process[] = {
1648  98, 75, 71, 68, '\0', /* bKGD */
1649  99, 72, 82, 77, '\0', /* cHRM */
1650  103, 65, 77, 65, '\0', /* gAMA */
1651 # ifdef PNG_READ_iCCP_SUPPORTED
1652  105, 67, 67, 80, '\0', /* iCCP */
1653 # endif
1654  115, 66, 73, 84, '\0', /* sBIT */
1655  115, 82, 71, 66, '\0', /* sRGB */
1656  };
1657 
1658  /* Ignore unknown chunks and all other chunks except for the
1659  * IHDR, PLTE, tRNS, IDAT, and IEND chunks.
1660  */
1662  NULL, -1);
1663 
1664  /* But do not ignore image data handling chunks */
1666  chunks_to_process, (int)/*SAFE*/(sizeof chunks_to_process)/5);
1667  }
1668 }
1669 
1670 # define PNG_SKIP_CHUNKS(p) png_image_skip_unused_chunks(p)
1671 #else
1672 # define PNG_SKIP_CHUNKS(p) ((void)0)
1673 #endif /* HANDLE_AS_UNKNOWN */
1674 
1675 /* The following macro gives the exact rounded answer for all values in the
1676  * range 0..255 (it actually divides by 51.2, but the rounding still generates
1677  * the correct numbers 0..5
1678  */
1679 #define PNG_DIV51(v8) (((v8) * 5 + 130) >> 8)
1680 
1681 /* Utility functions to make particular color-maps */
1682 static void
1684 {
1685  png_fixed_point g = display->image->opaque->png_ptr->colorspace.gamma;
1686  if (png_gamma_significant(g) != 0)
1687  {
1688  if (png_gamma_not_sRGB(g) != 0)
1689  {
1690  display->file_encoding = P_FILE;
1691  display->gamma_to_linear = png_reciprocal(g);
1692  }
1693 
1694  else
1695  display->file_encoding = P_sRGB;
1696  }
1697 
1698  else
1699  display->file_encoding = P_LINEAR8;
1700 }
1701 
1702 static unsigned int
1703 decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding)
1704 {
1705  if (encoding == P_FILE) /* double check */
1706  encoding = display->file_encoding;
1707 
1708  if (encoding == P_NOTSET) /* must be the file encoding */
1709  {
1710  set_file_encoding(display);
1711  encoding = display->file_encoding;
1712  }
1713 
1714  switch (encoding)
1715  {
1716  case P_FILE:
1717  value = png_gamma_16bit_correct(value*257, display->gamma_to_linear);
1718  break;
1719 
1720  case P_sRGB:
1721  value = png_sRGB_table[value];
1722  break;
1723 
1724  case P_LINEAR:
1725  break;
1726 
1727  case P_LINEAR8:
1728  value *= 257;
1729  break;
1730 
1731 #ifdef __GNUC__
1732  default:
1733  png_error(display->image->opaque->png_ptr,
1734  "unexpected encoding (internal error)");
1735 #endif
1736  }
1737 
1738  return value;
1739 }
1740 
1741 static png_uint_32
1743  png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha,
1744  png_uint_32 background, int encoding)
1745 {
1746  /* The file value is composed on the background, the background has the given
1747  * encoding and so does the result, the file is encoded with P_FILE and the
1748  * file and alpha are 8-bit values. The (output) encoding will always be
1749  * P_LINEAR or P_sRGB.
1750  */
1751  png_uint_32 f = decode_gamma(display, foreground, foreground_encoding);
1752  png_uint_32 b = decode_gamma(display, background, encoding);
1753 
1754  /* The alpha is always an 8-bit value (it comes from the palette), the value
1755  * scaled by 255 is what PNG_sRGB_FROM_LINEAR requires.
1756  */
1757  f = f * alpha + b * (255-alpha);
1758 
1759  if (encoding == P_LINEAR)
1760  {
1761  /* Scale to 65535; divide by 255, approximately (in fact this is extremely
1762  * accurate, it divides by 255.00000005937181414556, with no overflow.)
1763  */
1764  f *= 257; /* Now scaled by 65535 */
1765  f += f >> 16;
1766  f = (f+32768) >> 16;
1767  }
1768 
1769  else /* P_sRGB */
1770  f = PNG_sRGB_FROM_LINEAR(f);
1771 
1772  return f;
1773 }
1774 
1775 /* NOTE: P_LINEAR values to this routine must be 16-bit, but P_FILE values must
1776  * be 8-bit.
1777  */
1778 static void
1780  png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue,
1781  png_uint_32 alpha, int encoding)
1782 {
1783  png_imagep image = display->image;
1784  const int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
1785  P_LINEAR : P_sRGB;
1786  const int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 &&
1787  (red != green || green != blue);
1788 
1789  if (ip > 255)
1790  png_error(image->opaque->png_ptr, "color-map index out of range");
1791 
1792  /* Update the cache with whether the file gamma is significantly different
1793  * from sRGB.
1794  */
1795  if (encoding == P_FILE)
1796  {
1797  if (display->file_encoding == P_NOTSET)
1798  set_file_encoding(display);
1799 
1800  /* Note that the cached value may be P_FILE too, but if it is then the
1801  * gamma_to_linear member has been set.
1802  */
1803  encoding = display->file_encoding;
1804  }
1805 
1806  if (encoding == P_FILE)
1807  {
1808  png_fixed_point g = display->gamma_to_linear;
1809 
1810  red = png_gamma_16bit_correct(red*257, g);
1811  green = png_gamma_16bit_correct(green*257, g);
1812  blue = png_gamma_16bit_correct(blue*257, g);
1813 
1814  if (convert_to_Y != 0 || output_encoding == P_LINEAR)
1815  {
1816  alpha *= 257;
1817  encoding = P_LINEAR;
1818  }
1819 
1820  else
1821  {
1822  red = PNG_sRGB_FROM_LINEAR(red * 255);
1823  green = PNG_sRGB_FROM_LINEAR(green * 255);
1824  blue = PNG_sRGB_FROM_LINEAR(blue * 255);
1825  encoding = P_sRGB;
1826  }
1827  }
1828 
1829  else if (encoding == P_LINEAR8)
1830  {
1831  /* This encoding occurs quite frequently in test cases because PngSuite
1832  * includes a gAMA 1.0 chunk with most images.
1833  */
1834  red *= 257;
1835  green *= 257;
1836  blue *= 257;
1837  alpha *= 257;
1838  encoding = P_LINEAR;
1839  }
1840 
1841  else if (encoding == P_sRGB &&
1842  (convert_to_Y != 0 || output_encoding == P_LINEAR))
1843  {
1844  /* The values are 8-bit sRGB values, but must be converted to 16-bit
1845  * linear.
1846  */
1847  red = png_sRGB_table[red];
1848  green = png_sRGB_table[green];
1849  blue = png_sRGB_table[blue];
1850  alpha *= 257;
1851  encoding = P_LINEAR;
1852  }
1853 
1854  /* This is set if the color isn't gray but the output is. */
1855  if (encoding == P_LINEAR)
1856  {
1857  if (convert_to_Y != 0)
1858  {
1859  /* NOTE: these values are copied from png_do_rgb_to_gray */
1860  png_uint_32 y = (png_uint_32)6968 * red + (png_uint_32)23434 * green +
1861  (png_uint_32)2366 * blue;
1862 
1863  if (output_encoding == P_LINEAR)
1864  y = (y + 16384) >> 15;
1865 
1866  else
1867  {
1868  /* y is scaled by 32768, we need it scaled by 255: */
1869  y = (y + 128) >> 8;
1870  y *= 255;
1871  y = PNG_sRGB_FROM_LINEAR((y + 64) >> 7);
1872  alpha = PNG_DIV257(alpha);
1873  encoding = P_sRGB;
1874  }
1875 
1876  blue = red = green = y;
1877  }
1878 
1879  else if (output_encoding == P_sRGB)
1880  {
1881  red = PNG_sRGB_FROM_LINEAR(red * 255);
1882  green = PNG_sRGB_FROM_LINEAR(green * 255);
1883  blue = PNG_sRGB_FROM_LINEAR(blue * 255);
1884  alpha = PNG_DIV257(alpha);
1885  encoding = P_sRGB;
1886  }
1887  }
1888 
1889  if (encoding != output_encoding)
1890  png_error(image->opaque->png_ptr, "bad encoding (internal error)");
1891 
1892  /* Store the value. */
1893  {
1894 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
1895  const int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
1896  (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
1897 # else
1898 # define afirst 0
1899 # endif
1900 # ifdef PNG_FORMAT_BGR_SUPPORTED
1901  const int bgr = (image->format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
1902 # else
1903 # define bgr 0
1904 # endif
1905 
1906  if (output_encoding == P_LINEAR)
1907  {
1908  png_uint_16p entry = png_voidcast(png_uint_16p, display->colormap);
1909 
1910  entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
1911 
1912  /* The linear 16-bit values must be pre-multiplied by the alpha channel
1913  * value, if less than 65535 (this is, effectively, composite on black
1914  * if the alpha channel is removed.)
1915  */
1916  switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
1917  {
1918  case 4:
1919  entry[afirst ? 0 : 3] = (png_uint_16)alpha;
1920  /* FALLTHROUGH */
1921 
1922  case 3:
1923  if (alpha < 65535)
1924  {
1925  if (alpha > 0)
1926  {
1927  blue = (blue * alpha + 32767U)/65535U;
1928  green = (green * alpha + 32767U)/65535U;
1929  red = (red * alpha + 32767U)/65535U;
1930  }
1931 
1932  else
1933  red = green = blue = 0;
1934  }
1935  entry[afirst + (2 ^ bgr)] = (png_uint_16)blue;
1936  entry[afirst + 1] = (png_uint_16)green;
1937  entry[afirst + bgr] = (png_uint_16)red;
1938  break;
1939 
1940  case 2:
1941  entry[1 ^ afirst] = (png_uint_16)alpha;
1942  /* FALLTHROUGH */
1943 
1944  case 1:
1945  if (alpha < 65535)
1946  {
1947  if (alpha > 0)
1948  green = (green * alpha + 32767U)/65535U;
1949 
1950  else
1951  green = 0;
1952  }
1953  entry[afirst] = (png_uint_16)green;
1954  break;
1955 
1956  default:
1957  break;
1958  }
1959  }
1960 
1961  else /* output encoding is P_sRGB */
1962  {
1963  png_bytep entry = png_voidcast(png_bytep, display->colormap);
1964 
1965  entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
1966 
1967  switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
1968  {
1969  case 4:
1970  entry[afirst ? 0 : 3] = (png_byte)alpha;
1971  /* FALLTHROUGH */
1972  case 3:
1973  entry[afirst + (2 ^ bgr)] = (png_byte)blue;
1974  entry[afirst + 1] = (png_byte)green;
1975  entry[afirst + bgr] = (png_byte)red;
1976  break;
1977 
1978  case 2:
1979  entry[1 ^ afirst] = (png_byte)alpha;
1980  /* FALLTHROUGH */
1981  case 1:
1982  entry[afirst] = (png_byte)green;
1983  break;
1984 
1985  default:
1986  break;
1987  }
1988  }
1989 
1990 # ifdef afirst
1991 # undef afirst
1992 # endif
1993 # ifdef bgr
1994 # undef bgr
1995 # endif
1996  }
1997 }
1998 
1999 static int
2001 {
2002  unsigned int i;
2003 
2004  for (i=0; i<256; ++i)
2005  png_create_colormap_entry(display, i, i, i, i, 255, P_FILE);
2006 
2007  return (int)i;
2008 }
2009 
2010 static int
2012 {
2013  unsigned int i;
2014 
2015  for (i=0; i<256; ++i)
2016  png_create_colormap_entry(display, i, i, i, i, 255, P_sRGB);
2017 
2018  return (int)i;
2019 }
2020 #define PNG_GRAY_COLORMAP_ENTRIES 256
2021 
2022 static int
2024 {
2025  unsigned int i, a;
2026 
2027  /* Alpha is retained, the output will be a color-map with entries
2028  * selected by six levels of alpha. One transparent entry, 6 gray
2029  * levels for all the intermediate alpha values, leaving 230 entries
2030  * for the opaque grays. The color-map entries are the six values
2031  * [0..5]*51, the GA processing uses PNG_DIV51(value) to find the
2032  * relevant entry.
2033  *
2034  * if (alpha > 229) // opaque
2035  * {
2036  * // The 231 entries are selected to make the math below work:
2037  * base = 0;
2038  * entry = (231 * gray + 128) >> 8;
2039  * }
2040  * else if (alpha < 26) // transparent
2041  * {
2042  * base = 231;
2043  * entry = 0;
2044  * }
2045  * else // partially opaque
2046  * {
2047  * base = 226 + 6 * PNG_DIV51(alpha);
2048  * entry = PNG_DIV51(gray);
2049  * }
2050  */
2051  i = 0;
2052  while (i < 231)
2053  {
2054  unsigned int gray = (i * 256 + 115) / 231;
2055  png_create_colormap_entry(display, i++, gray, gray, gray, 255, P_sRGB);
2056  }
2057 
2058  /* 255 is used here for the component values for consistency with the code
2059  * that undoes premultiplication in pngwrite.c.
2060  */
2061  png_create_colormap_entry(display, i++, 255, 255, 255, 0, P_sRGB);
2062 
2063  for (a=1; a<5; ++a)
2064  {
2065  unsigned int g;
2066 
2067  for (g=0; g<6; ++g)
2068  png_create_colormap_entry(display, i++, g*51, g*51, g*51, a*51,
2069  P_sRGB);
2070  }
2071 
2072  return (int)i;
2073 }
2074 
2075 #define PNG_GA_COLORMAP_ENTRIES 256
2076 
2077 static int
2079 {
2080  unsigned int i, r;
2081 
2082  /* Build a 6x6x6 opaque RGB cube */
2083  for (i=r=0; r<6; ++r)
2084  {
2085  unsigned int g;
2086 
2087  for (g=0; g<6; ++g)
2088  {
2089  unsigned int b;
2090 
2091  for (b=0; b<6; ++b)
2092  png_create_colormap_entry(display, i++, r*51, g*51, b*51, 255,
2093  P_sRGB);
2094  }
2095  }
2096 
2097  return (int)i;
2098 }
2099 
2100 #define PNG_RGB_COLORMAP_ENTRIES 216
2101 
2102 /* Return a palette index to the above palette given three 8-bit sRGB values. */
2103 #define PNG_RGB_INDEX(r,g,b) \
2104  ((png_byte)(6 * (6 * PNG_DIV51(r) + PNG_DIV51(g)) + PNG_DIV51(b)))
2105 
2106 static int
2108 {
2109  png_image_read_control *display =
2111  const png_imagep image = display->image;
2112 
2113  const png_structrp png_ptr = image->opaque->png_ptr;
2114  const png_uint_32 output_format = image->format;
2115  const int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
2116  P_LINEAR : P_sRGB;
2117 
2118  unsigned int cmap_entries;
2119  unsigned int output_processing; /* Output processing option */
2120  unsigned int data_encoding = P_NOTSET; /* Encoding libpng must produce */
2121 
2122  /* Background information; the background color and the index of this color
2123  * in the color-map if it exists (else 256).
2124  */
2125  unsigned int background_index = 256;
2126  png_uint_32 back_r, back_g, back_b;
2127 
2128  /* Flags to accumulate things that need to be done to the input. */
2129  int expand_tRNS = 0;
2130 
2131  /* Exclude the NYI feature of compositing onto a color-mapped buffer; it is
2132  * very difficult to do, the results look awful, and it is difficult to see
2133  * what possible use it is because the application can't control the
2134  * color-map.
2135  */
2136  if (((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0 ||
2137  png_ptr->num_trans > 0) /* alpha in input */ &&
2138  ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) /* no alpha in output */)
2139  {
2140  if (output_encoding == P_LINEAR) /* compose on black */
2141  back_b = back_g = back_r = 0;
2142 
2143  else if (display->background == NULL /* no way to remove it */)
2144  png_error(png_ptr,
2145  "background color must be supplied to remove alpha/transparency");
2146 
2147  /* Get a copy of the background color (this avoids repeating the checks
2148  * below.) The encoding is 8-bit sRGB or 16-bit linear, depending on the
2149  * output format.
2150  */
2151  else
2152  {
2153  back_g = display->background->green;
2154  if ((output_format & PNG_FORMAT_FLAG_COLOR) != 0)
2155  {
2156  back_r = display->background->red;
2157  back_b = display->background->blue;
2158  }
2159  else
2160  back_b = back_r = back_g;
2161  }
2162  }
2163 
2164  else if (output_encoding == P_LINEAR)
2165  back_b = back_r = back_g = 65535;
2166 
2167  else
2168  back_b = back_r = back_g = 255;
2169 
2170  /* Default the input file gamma if required - this is necessary because
2171  * libpng assumes that if no gamma information is present the data is in the
2172  * output format, but the simplified API deduces the gamma from the input
2173  * format.
2174  */
2175  if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) == 0)
2176  {
2177  /* Do this directly, not using the png_colorspace functions, to ensure
2178  * that it happens even if the colorspace is invalid (though probably if
2179  * it is the setting will be ignored) Note that the same thing can be
2180  * achieved at the application interface with png_set_gAMA.
2181  */
2182  if (png_ptr->bit_depth == 16 &&
2183  (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
2184  png_ptr->colorspace.gamma = PNG_GAMMA_LINEAR;
2185 
2186  else
2187  png_ptr->colorspace.gamma = PNG_GAMMA_sRGB_INVERSE;
2188 
2189  png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
2190  }
2191 
2192  /* Decide what to do based on the PNG color type of the input data. The
2193  * utility function png_create_colormap_entry deals with most aspects of the
2194  * output transformations; this code works out how to produce bytes of
2195  * color-map entries from the original format.
2196  */
2197  switch (png_ptr->color_type)
2198  {
2199  case PNG_COLOR_TYPE_GRAY:
2200  if (png_ptr->bit_depth <= 8)
2201  {
2202  /* There at most 256 colors in the output, regardless of
2203  * transparency.
2204  */
2205  unsigned int step, i, val, trans = 256/*ignore*/, back_alpha = 0;
2206 
2207  cmap_entries = 1U << png_ptr->bit_depth;
2208  if (cmap_entries > image->colormap_entries)
2209  png_error(png_ptr, "gray[8] color-map: too few entries");
2210 
2211  step = 255 / (cmap_entries - 1);
2212  output_processing = PNG_CMAP_NONE;
2213 
2214  /* If there is a tRNS chunk then this either selects a transparent
2215  * value or, if the output has no alpha, the background color.
2216  */
2217  if (png_ptr->num_trans > 0)
2218  {
2219  trans = png_ptr->trans_color.gray;
2220 
2221  if ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0)
2222  back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
2223  }
2224 
2225  /* png_create_colormap_entry just takes an RGBA and writes the
2226  * corresponding color-map entry using the format from 'image',
2227  * including the required conversion to sRGB or linear as
2228  * appropriate. The input values are always either sRGB (if the
2229  * gamma correction flag is 0) or 0..255 scaled file encoded values
2230  * (if the function must gamma correct them).
2231  */
2232  for (i=val=0; i<cmap_entries; ++i, val += step)
2233  {
2234  /* 'i' is a file value. While this will result in duplicated
2235  * entries for 8-bit non-sRGB encoded files it is necessary to
2236  * have non-gamma corrected values to do tRNS handling.
2237  */
2238  if (i != trans)
2239  png_create_colormap_entry(display, i, val, val, val, 255,
2240  P_FILE/*8-bit with file gamma*/);
2241 
2242  /* Else this entry is transparent. The colors don't matter if
2243  * there is an alpha channel (back_alpha == 0), but it does no
2244  * harm to pass them in; the values are not set above so this
2245  * passes in white.
2246  *
2247  * NOTE: this preserves the full precision of the application
2248  * supplied background color when it is used.
2249  */
2250  else
2251  png_create_colormap_entry(display, i, back_r, back_g, back_b,
2252  back_alpha, output_encoding);
2253  }
2254 
2255  /* We need libpng to preserve the original encoding. */
2256  data_encoding = P_FILE;
2257 
2258  /* The rows from libpng, while technically gray values, are now also
2259  * color-map indices; however, they may need to be expanded to 1
2260  * byte per pixel. This is what png_set_packing does (i.e., it
2261  * unpacks the bit values into bytes.)
2262  */
2263  if (png_ptr->bit_depth < 8)
2264  png_set_packing(png_ptr);
2265  }
2266 
2267  else /* bit depth is 16 */
2268  {
2269  /* The 16-bit input values can be converted directly to 8-bit gamma
2270  * encoded values; however, if a tRNS chunk is present 257 color-map
2271  * entries are required. This means that the extra entry requires
2272  * special processing; add an alpha channel, sacrifice gray level
2273  * 254 and convert transparent (alpha==0) entries to that.
2274  *
2275  * Use libpng to chop the data to 8 bits. Convert it to sRGB at the
2276  * same time to minimize quality loss. If a tRNS chunk is present
2277  * this means libpng must handle it too; otherwise it is impossible
2278  * to do the exact match on the 16-bit value.
2279  *
2280  * If the output has no alpha channel *and* the background color is
2281  * gray then it is possible to let libpng handle the substitution by
2282  * ensuring that the corresponding gray level matches the background
2283  * color exactly.
2284  */
2285  data_encoding = P_sRGB;
2286 
2287  if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2288  png_error(png_ptr, "gray[16] color-map: too few entries");
2289 
2290  cmap_entries = (unsigned int)make_gray_colormap(display);
2291 
2292  if (png_ptr->num_trans > 0)
2293  {
2294  unsigned int back_alpha;
2295 
2296  if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2297  back_alpha = 0;
2298 
2299  else
2300  {
2301  if (back_r == back_g && back_g == back_b)
2302  {
2303  /* Background is gray; no special processing will be
2304  * required.
2305  */
2306  png_color_16 c;
2307  png_uint_32 gray = back_g;
2308 
2309  if (output_encoding == P_LINEAR)
2310  {
2311  gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2312 
2313  /* And make sure the corresponding palette entry
2314  * matches.
2315  */
2316  png_create_colormap_entry(display, gray, back_g, back_g,
2317  back_g, 65535, P_LINEAR);
2318  }
2319 
2320  /* The background passed to libpng, however, must be the
2321  * sRGB value.
2322  */
2323  c.index = 0; /*unused*/
2324  c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2325 
2326  /* NOTE: does this work without expanding tRNS to alpha?
2327  * It should be the color->gray case below apparently
2328  * doesn't.
2329  */
2330  png_set_background_fixed(png_ptr, &c,
2331  PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2332  0/*gamma: not used*/);
2333 
2334  output_processing = PNG_CMAP_NONE;
2335  break;
2336  }
2337 #ifdef __COVERITY__
2338  /* Coverity claims that output_encoding cannot be 2 (P_LINEAR)
2339  * here.
2340  */
2341  back_alpha = 255;
2342 #else
2343  back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
2344 #endif
2345  }
2346 
2347  /* output_processing means that the libpng-processed row will be
2348  * 8-bit GA and it has to be processing to single byte color-map
2349  * values. Entry 254 is replaced by either a completely
2350  * transparent entry or by the background color at full
2351  * precision (and the background color is not a simple gray
2352  * level in this case.)
2353  */
2354  expand_tRNS = 1;
2355  output_processing = PNG_CMAP_TRANS;
2356  background_index = 254;
2357 
2358  /* And set (overwrite) color-map entry 254 to the actual
2359  * background color at full precision.
2360  */
2361  png_create_colormap_entry(display, 254, back_r, back_g, back_b,
2362  back_alpha, output_encoding);
2363  }
2364 
2365  else
2366  output_processing = PNG_CMAP_NONE;
2367  }
2368  break;
2369 
2371  /* 8-bit or 16-bit PNG with two channels - gray and alpha. A minimum
2372  * of 65536 combinations. If, however, the alpha channel is to be
2373  * removed there are only 256 possibilities if the background is gray.
2374  * (Otherwise there is a subset of the 65536 possibilities defined by
2375  * the triangle between black, white and the background color.)
2376  *
2377  * Reduce 16-bit files to 8-bit and sRGB encode the result. No need to
2378  * worry about tRNS matching - tRNS is ignored if there is an alpha
2379  * channel.
2380  */
2381  data_encoding = P_sRGB;
2382 
2383  if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2384  {
2385  if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2386  png_error(png_ptr, "gray+alpha color-map: too few entries");
2387 
2388  cmap_entries = (unsigned int)make_ga_colormap(display);
2389 
2390  background_index = PNG_CMAP_GA_BACKGROUND;
2391  output_processing = PNG_CMAP_GA;
2392  }
2393 
2394  else /* alpha is removed */
2395  {
2396  /* Alpha must be removed as the PNG data is processed when the
2397  * background is a color because the G and A channels are
2398  * independent and the vector addition (non-parallel vectors) is a
2399  * 2-D problem.
2400  *
2401  * This can be reduced to the same algorithm as above by making a
2402  * colormap containing gray levels (for the opaque grays), a
2403  * background entry (for a transparent pixel) and a set of four six
2404  * level color values, one set for each intermediate alpha value.
2405  * See the comments in make_ga_colormap for how this works in the
2406  * per-pixel processing.
2407  *
2408  * If the background is gray, however, we only need a 256 entry gray
2409  * level color map. It is sufficient to make the entry generated
2410  * for the background color be exactly the color specified.
2411  */
2412  if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0 ||
2413  (back_r == back_g && back_g == back_b))
2414  {
2415  /* Background is gray; no special processing will be required. */
2416  png_color_16 c;
2417  png_uint_32 gray = back_g;
2418 
2419  if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2420  png_error(png_ptr, "gray-alpha color-map: too few entries");
2421 
2422  cmap_entries = (unsigned int)make_gray_colormap(display);
2423 
2424  if (output_encoding == P_LINEAR)
2425  {
2426  gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2427 
2428  /* And make sure the corresponding palette entry matches. */
2429  png_create_colormap_entry(display, gray, back_g, back_g,
2430  back_g, 65535, P_LINEAR);
2431  }
2432 
2433  /* The background passed to libpng, however, must be the sRGB
2434  * value.
2435  */
2436  c.index = 0; /*unused*/
2437  c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2438 
2439  png_set_background_fixed(png_ptr, &c,
2440  PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2441  0/*gamma: not used*/);
2442 
2443  output_processing = PNG_CMAP_NONE;
2444  }
2445 
2446  else
2447  {
2448  png_uint_32 i, a;
2449 
2450  /* This is the same as png_make_ga_colormap, above, except that
2451  * the entries are all opaque.
2452  */
2453  if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2454  png_error(png_ptr, "ga-alpha color-map: too few entries");
2455 
2456  i = 0;
2457  while (i < 231)
2458  {
2459  png_uint_32 gray = (i * 256 + 115) / 231;
2460  png_create_colormap_entry(display, i++, gray, gray, gray,
2461  255, P_sRGB);
2462  }
2463 
2464  /* NOTE: this preserves the full precision of the application
2465  * background color.
2466  */
2467  background_index = i;
2468  png_create_colormap_entry(display, i++, back_r, back_g, back_b,
2469 #ifdef __COVERITY__
2470  /* Coverity claims that output_encoding
2471  * cannot be 2 (P_LINEAR) here.
2472  */ 255U,
2473 #else
2474  output_encoding == P_LINEAR ? 65535U : 255U,
2475 #endif
2476  output_encoding);
2477 
2478  /* For non-opaque input composite on the sRGB background - this
2479  * requires inverting the encoding for each component. The input
2480  * is still converted to the sRGB encoding because this is a
2481  * reasonable approximate to the logarithmic curve of human
2482  * visual sensitivity, at least over the narrow range which PNG
2483  * represents. Consequently 'G' is always sRGB encoded, while
2484  * 'A' is linear. We need the linear background colors.
2485  */
2486  if (output_encoding == P_sRGB) /* else already linear */
2487  {
2488  /* This may produce a value not exactly matching the
2489  * background, but that's ok because these numbers are only
2490  * used when alpha != 0
2491  */
2492  back_r = png_sRGB_table[back_r];
2493  back_g = png_sRGB_table[back_g];
2494  back_b = png_sRGB_table[back_b];
2495  }
2496 
2497  for (a=1; a<5; ++a)
2498  {
2499  unsigned int g;
2500 
2501  /* PNG_sRGB_FROM_LINEAR expects a 16-bit linear value scaled
2502  * by an 8-bit alpha value (0..255).
2503  */
2504  png_uint_32 alpha = 51 * a;
2505  png_uint_32 back_rx = (255-alpha) * back_r;
2506  png_uint_32 back_gx = (255-alpha) * back_g;
2507  png_uint_32 back_bx = (255-alpha) * back_b;
2508 
2509  for (g=0; g<6; ++g)
2510  {
2511  png_uint_32 gray = png_sRGB_table[g*51] * alpha;
2512 
2513  png_create_colormap_entry(display, i++,
2514  PNG_sRGB_FROM_LINEAR(gray + back_rx),
2515  PNG_sRGB_FROM_LINEAR(gray + back_gx),
2516  PNG_sRGB_FROM_LINEAR(gray + back_bx), 255, P_sRGB);
2517  }
2518  }
2519 
2520  cmap_entries = i;
2521  output_processing = PNG_CMAP_GA;
2522  }
2523  }
2524  break;
2525 
2526  case PNG_COLOR_TYPE_RGB:
2528  /* Exclude the case where the output is gray; we can always handle this
2529  * with the cases above.
2530  */
2531  if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0)
2532  {
2533  /* The color-map will be grayscale, so we may as well convert the
2534  * input RGB values to a simple grayscale and use the grayscale
2535  * code above.
2536  *
2537  * NOTE: calling this apparently damages the recognition of the
2538  * transparent color in background color handling; call
2539  * png_set_tRNS_to_alpha before png_set_background_fixed.
2540  */
2542  -1);
2543  data_encoding = P_sRGB;
2544 
2545  /* The output will now be one or two 8-bit gray or gray+alpha
2546  * channels. The more complex case arises when the input has alpha.
2547  */
2548  if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2549  png_ptr->num_trans > 0) &&
2550  (output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2551  {
2552  /* Both input and output have an alpha channel, so no background
2553  * processing is required; just map the GA bytes to the right
2554  * color-map entry.
2555  */
2556  expand_tRNS = 1;
2557 
2558  if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2559  png_error(png_ptr, "rgb[ga] color-map: too few entries");
2560 
2561  cmap_entries = (unsigned int)make_ga_colormap(display);
2562  background_index = PNG_CMAP_GA_BACKGROUND;
2563  output_processing = PNG_CMAP_GA;
2564  }
2565 
2566  else
2567  {
2568  /* Either the input or the output has no alpha channel, so there
2569  * will be no non-opaque pixels in the color-map; it will just be
2570  * grayscale.
2571  */
2572  if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2573  png_error(png_ptr, "rgb[gray] color-map: too few entries");
2574 
2575  /* Ideally this code would use libpng to do the gamma correction,
2576  * but if an input alpha channel is to be removed we will hit the
2577  * libpng bug in gamma+compose+rgb-to-gray (the double gamma
2578  * correction bug). Fix this by dropping the gamma correction in
2579  * this case and doing it in the palette; this will result in
2580  * duplicate palette entries, but that's better than the
2581  * alternative of double gamma correction.
2582  */
2583  if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2584  png_ptr->num_trans > 0) &&
2585  png_gamma_not_sRGB(png_ptr->colorspace.gamma) != 0)
2586  {
2587  cmap_entries = (unsigned int)make_gray_file_colormap(display);
2588  data_encoding = P_FILE;
2589  }
2590 
2591  else
2592  cmap_entries = (unsigned int)make_gray_colormap(display);
2593 
2594  /* But if the input has alpha or transparency it must be removed
2595  */
2596  if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2597  png_ptr->num_trans > 0)
2598  {
2599  png_color_16 c;
2600  png_uint_32 gray = back_g;
2601 
2602  /* We need to ensure that the application background exists in
2603  * the colormap and that completely transparent pixels map to
2604  * it. Achieve this simply by ensuring that the entry
2605  * selected for the background really is the background color.
2606  */
2607  if (data_encoding == P_FILE) /* from the fixup above */
2608  {
2609  /* The app supplied a gray which is in output_encoding, we
2610  * need to convert it to a value of the input (P_FILE)
2611  * encoding then set this palette entry to the required
2612  * output encoding.
2613  */
2614  if (output_encoding == P_sRGB)
2615  gray = png_sRGB_table[gray]; /* now P_LINEAR */
2616 
2617  gray = PNG_DIV257(png_gamma_16bit_correct(gray,
2618  png_ptr->colorspace.gamma)); /* now P_FILE */
2619 
2620  /* And make sure the corresponding palette entry contains
2621  * exactly the required sRGB value.
2622  */
2623  png_create_colormap_entry(display, gray, back_g, back_g,
2624  back_g, 0/*unused*/, output_encoding);
2625  }
2626 
2627  else if (output_encoding == P_LINEAR)
2628  {
2629  gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2630 
2631  /* And make sure the corresponding palette entry matches.
2632  */
2633  png_create_colormap_entry(display, gray, back_g, back_g,
2634  back_g, 0/*unused*/, P_LINEAR);
2635  }
2636 
2637  /* The background passed to libpng, however, must be the
2638  * output (normally sRGB) value.
2639  */
2640  c.index = 0; /*unused*/
2641  c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2642 
2643  /* NOTE: the following is apparently a bug in libpng. Without
2644  * it the transparent color recognition in
2645  * png_set_background_fixed seems to go wrong.
2646  */
2647  expand_tRNS = 1;
2648  png_set_background_fixed(png_ptr, &c,
2649  PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2650  0/*gamma: not used*/);
2651  }
2652 
2653  output_processing = PNG_CMAP_NONE;
2654  }
2655  }
2656 
2657  else /* output is color */
2658  {
2659  /* We could use png_quantize here so long as there is no transparent
2660  * color or alpha; png_quantize ignores alpha. Easier overall just
2661  * to do it once and using PNG_DIV51 on the 6x6x6 reduced RGB cube.
2662  * Consequently we always want libpng to produce sRGB data.
2663  */
2664  data_encoding = P_sRGB;
2665 
2666  /* Is there any transparency or alpha? */
2667  if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2668  png_ptr->num_trans > 0)
2669  {
2670  /* Is there alpha in the output too? If so all four channels are
2671  * processed into a special RGB cube with alpha support.
2672  */
2673  if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2674  {
2675  png_uint_32 r;
2676 
2677  if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
2678  png_error(png_ptr, "rgb+alpha color-map: too few entries");
2679 
2680  cmap_entries = (unsigned int)make_rgb_colormap(display);
2681 
2682  /* Add a transparent entry. */
2683  png_create_colormap_entry(display, cmap_entries, 255, 255,
2684  255, 0, P_sRGB);
2685 
2686  /* This is stored as the background index for the processing
2687  * algorithm.
2688  */
2689  background_index = cmap_entries++;
2690 
2691  /* Add 27 r,g,b entries each with alpha 0.5. */
2692  for (r=0; r<256; r = (r << 1) | 0x7f)
2693  {
2694  png_uint_32 g;
2695 
2696  for (g=0; g<256; g = (g << 1) | 0x7f)
2697  {
2698  png_uint_32 b;
2699 
2700  /* This generates components with the values 0, 127 and
2701  * 255
2702  */
2703  for (b=0; b<256; b = (b << 1) | 0x7f)
2704  png_create_colormap_entry(display, cmap_entries++,
2705  r, g, b, 128, P_sRGB);
2706  }
2707  }
2708 
2709  expand_tRNS = 1;
2710  output_processing = PNG_CMAP_RGB_ALPHA;
2711  }
2712 
2713  else
2714  {
2715  /* Alpha/transparency must be removed. The background must
2716  * exist in the color map (achieved by setting adding it after
2717  * the 666 color-map). If the standard processing code will
2718  * pick up this entry automatically that's all that is
2719  * required; libpng can be called to do the background
2720  * processing.
2721  */
2722  unsigned int sample_size =
2723  PNG_IMAGE_SAMPLE_SIZE(output_format);
2724  png_uint_32 r, g, b; /* sRGB background */
2725 
2726  if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
2727  png_error(png_ptr, "rgb-alpha color-map: too few entries");
2728 
2729  cmap_entries = (unsigned int)make_rgb_colormap(display);
2730 
2731  png_create_colormap_entry(display, cmap_entries, back_r,
2732  back_g, back_b, 0/*unused*/, output_encoding);
2733 
2734  if (output_encoding == P_LINEAR)
2735  {
2736  r = PNG_sRGB_FROM_LINEAR(back_r * 255);
2737  g = PNG_sRGB_FROM_LINEAR(back_g * 255);
2738  b = PNG_sRGB_FROM_LINEAR(back_b * 255);
2739  }
2740 
2741  else
2742  {
2743  r = back_r;
2744  g = back_g;
2745  b = back_g;
2746  }
2747 
2748  /* Compare the newly-created color-map entry with the one the
2749  * PNG_CMAP_RGB algorithm will use. If the two entries don't
2750  * match, add the new one and set this as the background
2751  * index.
2752  */
2753  if (memcmp((png_const_bytep)display->colormap +
2754  sample_size * cmap_entries,
2755  (png_const_bytep)display->colormap +
2756  sample_size * PNG_RGB_INDEX(r,g,b),
2757  sample_size) != 0)
2758  {
2759  /* The background color must be added. */
2760  background_index = cmap_entries++;
2761 
2762  /* Add 27 r,g,b entries each with created by composing with
2763  * the background at alpha 0.5.
2764  */
2765  for (r=0; r<256; r = (r << 1) | 0x7f)
2766  {
2767  for (g=0; g<256; g = (g << 1) | 0x7f)
2768  {
2769  /* This generates components with the values 0, 127
2770  * and 255
2771  */
2772  for (b=0; b<256; b = (b << 1) | 0x7f)
2773  png_create_colormap_entry(display, cmap_entries++,
2774  png_colormap_compose(display, r, P_sRGB, 128,
2775  back_r, output_encoding),
2776  png_colormap_compose(display, g, P_sRGB, 128,
2777  back_g, output_encoding),
2778  png_colormap_compose(display, b, P_sRGB, 128,
2779  back_b, output_encoding),
2780  0/*unused*/, output_encoding);
2781  }
2782  }
2783 
2784  expand_tRNS = 1;
2785  output_processing = PNG_CMAP_RGB_ALPHA;
2786  }
2787 
2788  else /* background color is in the standard color-map */
2789  {
2790  png_color_16 c;
2791 
2792  c.index = 0; /*unused*/
2793  c.red = (png_uint_16)back_r;
2794  c.gray = c.green = (png_uint_16)back_g;
2795  c.blue = (png_uint_16)back_b;
2796 
2797  png_set_background_fixed(png_ptr, &c,
2798  PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2799  0/*gamma: not used*/);
2800 
2801  output_processing = PNG_CMAP_RGB;
2802  }
2803  }
2804  }
2805 
2806  else /* no alpha or transparency in the input */
2807  {
2808  /* Alpha in the output is irrelevant, simply map the opaque input
2809  * pixels to the 6x6x6 color-map.
2810  */
2811  if (PNG_RGB_COLORMAP_ENTRIES > image->colormap_entries)
2812  png_error(png_ptr, "rgb color-map: too few entries");
2813 
2814  cmap_entries = (unsigned int)make_rgb_colormap(display);
2815  output_processing = PNG_CMAP_RGB;
2816  }
2817  }
2818  break;
2819 
2821  /* It's already got a color-map. It may be necessary to eliminate the
2822  * tRNS entries though.
2823  */
2824  {
2825  unsigned int num_trans = png_ptr->num_trans;
2826  png_const_bytep trans = num_trans > 0 ? png_ptr->trans_alpha : NULL;
2827  png_const_colorp colormap = png_ptr->palette;
2828  const int do_background = trans != NULL &&
2829  (output_format & PNG_FORMAT_FLAG_ALPHA) == 0;
2830  unsigned int i;
2831 
2832  /* Just in case: */
2833  if (trans == NULL)
2834  num_trans = 0;
2835 
2836  output_processing = PNG_CMAP_NONE;
2837  data_encoding = P_FILE; /* Don't change from color-map indices */
2838  cmap_entries = (unsigned int)png_ptr->num_palette;
2839  if (cmap_entries > 256)
2840  cmap_entries = 256;
2841 
2842  if (cmap_entries > (unsigned int)image->colormap_entries)
2843  png_error(png_ptr, "palette color-map: too few entries");
2844 
2845  for (i=0; i < cmap_entries; ++i)
2846  {
2847  if (do_background != 0 && i < num_trans && trans[i] < 255)
2848  {
2849  if (trans[i] == 0)
2850  png_create_colormap_entry(display, i, back_r, back_g,
2851  back_b, 0, output_encoding);
2852 
2853  else
2854  {
2855  /* Must compose the PNG file color in the color-map entry
2856  * on the sRGB color in 'back'.
2857  */
2858  png_create_colormap_entry(display, i,
2859  png_colormap_compose(display, colormap[i].red,
2860  P_FILE, trans[i], back_r, output_encoding),
2861  png_colormap_compose(display, colormap[i].green,
2862  P_FILE, trans[i], back_g, output_encoding),
2863  png_colormap_compose(display, colormap[i].blue,
2864  P_FILE, trans[i], back_b, output_encoding),
2865  output_encoding == P_LINEAR ? trans[i] * 257U :
2866  trans[i],
2867  output_encoding);
2868  }
2869  }
2870 
2871  else
2872  png_create_colormap_entry(display, i, colormap[i].red,
2873  colormap[i].green, colormap[i].blue,
2874  i < num_trans ? trans[i] : 255U, P_FILE/*8-bit*/);
2875  }
2876 
2877  /* The PNG data may have indices packed in fewer than 8 bits, it
2878  * must be expanded if so.
2879  */
2880  if (png_ptr->bit_depth < 8)
2881  png_set_packing(png_ptr);
2882  }
2883  break;
2884 
2885  default:
2886  png_error(png_ptr, "invalid PNG color type");
2887  /*NOT REACHED*/
2888  }
2889 
2890  /* Now deal with the output processing */
2891  if (expand_tRNS != 0 && png_ptr->num_trans > 0 &&
2892  (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0)
2893  png_set_tRNS_to_alpha(png_ptr);
2894 
2895  switch (data_encoding)
2896  {
2897  case P_sRGB:
2898  /* Change to 8-bit sRGB */
2899  png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB);
2900  /* FALLTHROUGH */
2901 
2902  case P_FILE:
2903  if (png_ptr->bit_depth > 8)
2904  png_set_scale_16(png_ptr);
2905  break;
2906 
2907 #ifdef __GNUC__
2908  default:
2909  png_error(png_ptr, "bad data option (internal error)");
2910 #endif
2911  }
2912 
2913  if (cmap_entries > 256 || cmap_entries > image->colormap_entries)
2914  png_error(png_ptr, "color map overflow (BAD internal error)");
2915 
2916  image->colormap_entries = cmap_entries;
2917 
2918  /* Double check using the recorded background index */
2919  switch (output_processing)
2920  {
2921  case PNG_CMAP_NONE:
2922  if (background_index != PNG_CMAP_NONE_BACKGROUND)
2923  goto bad_background;
2924  break;
2925 
2926  case PNG_CMAP_GA:
2927  if (background_index != PNG_CMAP_GA_BACKGROUND)
2928  goto bad_background;
2929  break;
2930 
2931  case PNG_CMAP_TRANS:
2932  if (background_index >= cmap_entries ||
2933  background_index != PNG_CMAP_TRANS_BACKGROUND)
2934  goto bad_background;
2935  break;
2936 
2937  case PNG_CMAP_RGB:
2938  if (background_index != PNG_CMAP_RGB_BACKGROUND)
2939  goto bad_background;
2940  break;
2941 
2942  case PNG_CMAP_RGB_ALPHA:
2943  if (background_index != PNG_CMAP_RGB_ALPHA_BACKGROUND)
2944  goto bad_background;
2945  break;
2946 
2947  default:
2948  png_error(png_ptr, "bad processing option (internal error)");
2949 
2950  bad_background:
2951  png_error(png_ptr, "bad background index (internal error)");
2952  }
2953 
2954  display->colormap_processing = (int)output_processing;
2955 
2956  return 1/*ok*/;
2957 }
2958 
2959 /* The final part of the color-map read called from png_image_finish_read. */
2960 static int
2962 {
2964  argument);
2965  png_imagep image = display->image;
2966  png_structrp png_ptr = image->opaque->png_ptr;
2967  int passes;
2968 
2969  /* Called when the libpng data must be transformed into the color-mapped
2970  * form. There is a local row buffer in display->local and this routine must
2971  * do the interlace handling.
2972  */
2973  switch (png_ptr->interlaced)
2974  {
2975  case PNG_INTERLACE_NONE:
2976  passes = 1;
2977  break;
2978 
2979  case PNG_INTERLACE_ADAM7:
2980  passes = PNG_INTERLACE_ADAM7_PASSES;
2981  break;
2982 
2983  default:
2984  png_error(png_ptr, "unknown interlace type");
2985  }
2986 
2987  {
2988  png_uint_32 height = image->height;
2989  png_uint_32 width = image->width;
2990  int proc = display->colormap_processing;
2991  png_bytep first_row = png_voidcast(png_bytep, display->first_row);
2992  ptrdiff_t step_row = display->row_bytes;
2993  int pass;
2994 
2995  for (pass = 0; pass < passes; ++pass)
2996  {
2997  unsigned int startx, stepx, stepy;
2998  png_uint_32 y;
2999 
3000  if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3001  {
3002  /* The row may be empty for a short image: */
3003  if (PNG_PASS_COLS(width, pass) == 0)
3004  continue;
3005 
3006  startx = PNG_PASS_START_COL(pass);
3007  stepx = PNG_PASS_COL_OFFSET(pass);
3008  y = PNG_PASS_START_ROW(pass);
3009  stepy = PNG_PASS_ROW_OFFSET(pass);
3010  }
3011 
3012  else
3013  {
3014  y = 0;
3015  startx = 0;
3016  stepx = stepy = 1;
3017  }
3018 
3019  for (; y<height; y += stepy)
3020  {
3021  png_bytep inrow = png_voidcast(png_bytep, display->local_row);
3022  png_bytep outrow = first_row + y * step_row;
3023  png_const_bytep end_row = outrow + width;
3024 
3025  /* Read read the libpng data into the temporary buffer. */
3026  png_read_row(png_ptr, inrow, NULL);
3027 
3028  /* Now process the row according to the processing option, note
3029  * that the caller verifies that the format of the libpng output
3030  * data is as required.
3031  */
3032  outrow += startx;
3033  switch (proc)
3034  {
3035  case PNG_CMAP_GA:
3036  for (; outrow < end_row; outrow += stepx)
3037  {
3038  /* The data is always in the PNG order */
3039  unsigned int gray = *inrow++;
3040  unsigned int alpha = *inrow++;
3041  unsigned int entry;
3042 
3043  /* NOTE: this code is copied as a comment in
3044  * make_ga_colormap above. Please update the
3045  * comment if you change this code!
3046  */
3047  if (alpha > 229) /* opaque */
3048  {
3049  entry = (231 * gray + 128) >> 8;
3050  }
3051  else if (alpha < 26) /* transparent */
3052  {
3053  entry = 231;
3054  }
3055  else /* partially opaque */
3056  {
3057  entry = 226 + 6 * PNG_DIV51(alpha) + PNG_DIV51(gray);
3058  }
3059 
3060  *outrow = (png_byte)entry;
3061  }
3062  break;
3063 
3064  case PNG_CMAP_TRANS:
3065  for (; outrow < end_row; outrow += stepx)
3066  {
3067  png_byte gray = *inrow++;
3068  png_byte alpha = *inrow++;
3069 
3070  if (alpha == 0)
3071  *outrow = PNG_CMAP_TRANS_BACKGROUND;
3072 
3073  else if (gray != PNG_CMAP_TRANS_BACKGROUND)
3074  *outrow = gray;
3075 
3076  else
3077  *outrow = (png_byte)(PNG_CMAP_TRANS_BACKGROUND+1);
3078  }
3079  break;
3080 
3081  case PNG_CMAP_RGB:
3082  for (; outrow < end_row; outrow += stepx)
3083  {
3084  *outrow = PNG_RGB_INDEX(inrow[0], inrow[1], inrow[2]);
3085  inrow += 3;
3086  }
3087  break;
3088 
3089  case PNG_CMAP_RGB_ALPHA:
3090  for (; outrow < end_row; outrow += stepx)
3091  {
3092  unsigned int alpha = inrow[3];
3093 
3094  /* Because the alpha entries only hold alpha==0.5 values
3095  * split the processing at alpha==0.25 (64) and 0.75
3096  * (196).
3097  */
3098 
3099  if (alpha >= 196)
3100  *outrow = PNG_RGB_INDEX(inrow[0], inrow[1],
3101  inrow[2]);
3102 
3103  else if (alpha < 64)
3105 
3106  else
3107  {
3108  /* Likewise there are three entries for each of r, g
3109  * and b. We could select the entry by popcount on
3110  * the top two bits on those architectures that
3111  * support it, this is what the code below does,
3112  * crudely.
3113  */
3114  unsigned int back_i = PNG_CMAP_RGB_ALPHA_BACKGROUND+1;
3115 
3116  /* Here are how the values map:
3117  *
3118  * 0x00 .. 0x3f -> 0
3119  * 0x40 .. 0xbf -> 1
3120  * 0xc0 .. 0xff -> 2
3121  *
3122  * So, as above with the explicit alpha checks, the
3123  * breakpoints are at 64 and 196.
3124  */
3125  if (inrow[0] & 0x80) back_i += 9; /* red */
3126  if (inrow[0] & 0x40) back_i += 9;
3127  if (inrow[0] & 0x80) back_i += 3; /* green */
3128  if (inrow[0] & 0x40) back_i += 3;
3129  if (inrow[0] & 0x80) back_i += 1; /* blue */
3130  if (inrow[0] & 0x40) back_i += 1;
3131 
3132  *outrow = (png_byte)back_i;
3133  }
3134 
3135  inrow += 4;
3136  }
3137  break;
3138 
3139  default:
3140  break;
3141  }
3142  }
3143  }
3144  }
3145 
3146  return 1;
3147 }
3148 
3149 static int
3151 {
3153  argument);
3154  png_imagep image = display->image;
3155  png_controlp control = image->opaque;
3156  png_structrp png_ptr = control->png_ptr;
3157  png_inforp info_ptr = control->info_ptr;
3158 
3159  int passes = 0; /* As a flag */
3160 
3161  PNG_SKIP_CHUNKS(png_ptr);
3162 
3163  /* Update the 'info' structure and make sure the result is as required; first
3164  * make sure to turn on the interlace handling if it will be required
3165  * (because it can't be turned on *after* the call to png_read_update_info!)
3166  */
3167  if (display->colormap_processing == PNG_CMAP_NONE)
3168  passes = png_set_interlace_handling(png_ptr);
3169 
3170  png_read_update_info(png_ptr, info_ptr);
3171 
3172  /* The expected output can be deduced from the colormap_processing option. */
3173  switch (display->colormap_processing)
3174  {
3175  case PNG_CMAP_NONE:
3176  /* Output must be one channel and one byte per pixel, the output
3177  * encoding can be anything.
3178  */
3179  if ((info_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
3180  info_ptr->color_type == PNG_COLOR_TYPE_GRAY) &&
3181  info_ptr->bit_depth == 8)
3182  break;
3183 
3184  goto bad_output;
3185 
3186  case PNG_CMAP_TRANS:
3187  case PNG_CMAP_GA:
3188  /* Output must be two channels and the 'G' one must be sRGB, the latter
3189  * can be checked with an exact number because it should have been set
3190  * to this number above!
3191  */
3192  if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA &&
3193  info_ptr->bit_depth == 8 &&
3194  png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3195  image->colormap_entries == 256)
3196  break;
3197 
3198  goto bad_output;
3199 
3200  case PNG_CMAP_RGB:
3201  /* Output must be 8-bit sRGB encoded RGB */
3202  if (info_ptr->color_type == PNG_COLOR_TYPE_RGB &&
3203  info_ptr->bit_depth == 8 &&
3204  png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3205  image->colormap_entries == 216)
3206  break;
3207 
3208  goto bad_output;
3209 
3210  case PNG_CMAP_RGB_ALPHA:
3211  /* Output must be 8-bit sRGB encoded RGBA */
3212  if (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
3213  info_ptr->bit_depth == 8 &&
3214  png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3215  image->colormap_entries == 244 /* 216 + 1 + 27 */)
3216  break;
3217 
3218  goto bad_output;
3219 
3220  default:
3221  bad_output:
3222  png_error(png_ptr, "bad color-map processing (internal error)");
3223  }
3224 
3225  /* Now read the rows. Do this here if it is possible to read directly into
3226  * the output buffer, otherwise allocate a local row buffer of the maximum
3227  * size libpng requires and call the relevant processing routine safely.
3228  */
3229  {
3230  png_voidp first_row = display->buffer;
3231  ptrdiff_t row_bytes = display->row_stride;
3232 
3233  /* The following expression is designed to work correctly whether it gives
3234  * a signed or an unsigned result.
3235  */
3236  if (row_bytes < 0)
3237  {
3238  char *ptr = png_voidcast(char*, first_row);
3239  ptr += (image->height-1) * (-row_bytes);
3240  first_row = png_voidcast(png_voidp, ptr);
3241  }
3242 
3243  display->first_row = first_row;
3244  display->row_bytes = row_bytes;
3245  }
3246 
3247  if (passes == 0)
3248  {
3249  int result;
3250  png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
3251 
3252  display->local_row = row;
3253  result = png_safe_execute(image, png_image_read_and_map, display);
3254  display->local_row = NULL;
3255  png_free(png_ptr, row);
3256 
3257  return result;
3258  }
3259 
3260  else
3261  {
3262  png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes;
3263 
3264  while (--passes >= 0)
3265  {
3266  png_uint_32 y = image->height;
3267  png_bytep row = png_voidcast(png_bytep, display->first_row);
3268 
3269  for (; y > 0; --y)
3270  {
3271  png_read_row(png_ptr, row, NULL);
3272  row += row_bytes;
3273  }
3274  }
3275 
3276  return 1;
3277  }
3278 }
3279 
3280 /* Just the row reading part of png_image_read. */
3281 static int
3283 {
3285  argument);
3286  png_imagep image = display->image;
3287  png_structrp png_ptr = image->opaque->png_ptr;
3288  int passes;
3289 
3290  switch (png_ptr->interlaced)
3291  {
3292  case PNG_INTERLACE_NONE:
3293  passes = 1;
3294  break;
3295 
3296  case PNG_INTERLACE_ADAM7:
3297  passes = PNG_INTERLACE_ADAM7_PASSES;
3298  break;
3299 
3300  default:
3301  png_error(png_ptr, "unknown interlace type");
3302  }
3303 
3304  {
3305  png_uint_32 height = image->height;
3306  png_uint_32 width = image->width;
3307  ptrdiff_t step_row = display->row_bytes;
3308  unsigned int channels =
3309  (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
3310  int pass;
3311 
3312  for (pass = 0; pass < passes; ++pass)
3313  {
3314  unsigned int startx, stepx, stepy;
3315  png_uint_32 y;
3316 
3317  if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3318  {
3319  /* The row may be empty for a short image: */
3320  if (PNG_PASS_COLS(width, pass) == 0)
3321  continue;
3322 
3323  startx = PNG_PASS_START_COL(pass) * channels;
3324  stepx = PNG_PASS_COL_OFFSET(pass) * channels;
3325  y = PNG_PASS_START_ROW(pass);
3326  stepy = PNG_PASS_ROW_OFFSET(pass);
3327  }
3328 
3329  else
3330  {
3331  y = 0;
3332  startx = 0;
3333  stepx = channels;
3334  stepy = 1;
3335  }
3336 
3337  for (; y<height; y += stepy)
3338  {
3339  png_bytep inrow = png_voidcast(png_bytep, display->local_row);
3340  png_bytep outrow;
3341  png_const_bytep end_row;
3342 
3343  /* Read the row, which is packed: */
3344  png_read_row(png_ptr, inrow, NULL);
3345 
3346  outrow = png_voidcast(png_bytep, display->first_row);
3347  outrow += y * step_row;
3348  end_row = outrow + width * channels;
3349 
3350  /* Now do the composition on each pixel in this row. */
3351  outrow += startx;
3352  for (; outrow < end_row; outrow += stepx)
3353  {
3354  png_byte alpha = inrow[channels];
3355 
3356  if (alpha > 0) /* else no change to the output */
3357  {
3358  unsigned int c;
3359 
3360  for (c=0; c<channels; ++c)
3361  {
3362  png_uint_32 component = inrow[c];
3363 
3364  if (alpha < 255) /* else just use component */
3365  {
3366  /* This is PNG_OPTIMIZED_ALPHA, the component value
3367  * is a linear 8-bit value. Combine this with the
3368  * current outrow[c] value which is sRGB encoded.
3369  * Arithmetic here is 16-bits to preserve the output
3370  * values correctly.
3371  */
3372  component *= 257*255; /* =65535 */
3373  component += (255-alpha)*png_sRGB_table[outrow[c]];
3374 
3375  /* So 'component' is scaled by 255*65535 and is
3376  * therefore appropriate for the sRGB to linear
3377  * conversion table.
3378  */
3379  component = PNG_sRGB_FROM_LINEAR(component);
3380  }
3381 
3382  outrow[c] = (png_byte)component;
3383  }
3384  }
3385 
3386  inrow += channels+1; /* components and alpha channel */
3387  }
3388  }
3389  }
3390  }
3391 
3392  return 1;
3393 }
3394 
3395 /* The do_local_background case; called when all the following transforms are to
3396  * be done:
3397  *
3398  * PNG_RGB_TO_GRAY
3399  * PNG_COMPOSITE
3400  * PNG_GAMMA
3401  *
3402  * This is a work-around for the fact that both the PNG_RGB_TO_GRAY and
3403  * PNG_COMPOSITE code performs gamma correction, so we get double gamma
3404  * correction. The fix-up is to prevent the PNG_COMPOSITE operation from
3405  * happening inside libpng, so this routine sees an 8 or 16-bit gray+alpha
3406  * row and handles the removal or pre-multiplication of the alpha channel.
3407  */
3408 static int
3410 {
3412  argument);
3413  png_imagep image = display->image;
3414  png_structrp png_ptr = image->opaque->png_ptr;
3415  png_inforp info_ptr = image->opaque->info_ptr;
3416  png_uint_32 height = image->height;
3417  png_uint_32 width = image->width;
3418  int pass, passes;
3419 
3420  /* Double check the convoluted logic below. We expect to get here with
3421  * libpng doing rgb to gray and gamma correction but background processing
3422  * left to the png_image_read_background function. The rows libpng produce
3423  * might be 8 or 16-bit but should always have two channels; gray plus alpha.
3424  */
3425  if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
3426  png_error(png_ptr, "lost rgb to gray");
3427 
3428  if ((png_ptr->transformations & PNG_COMPOSE) != 0)
3429  png_error(png_ptr, "unexpected compose");
3430 
3431  if (png_get_channels(png_ptr, info_ptr) != 2)
3432  png_error(png_ptr, "lost/gained channels");
3433 
3434  /* Expect the 8-bit case to always remove the alpha channel */
3435  if ((image->format & PNG_FORMAT_FLAG_LINEAR) == 0 &&
3436  (image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
3437  png_error(png_ptr, "unexpected 8-bit transformation");
3438 
3439  switch (png_ptr->interlaced)
3440  {
3441  case PNG_INTERLACE_NONE:
3442  passes = 1;
3443  break;
3444 
3445  case PNG_INTERLACE_ADAM7:
3446  passes = PNG_INTERLACE_ADAM7_PASSES;
3447  break;
3448 
3449  default:
3450  png_error(png_ptr, "unknown interlace type");
3451  }
3452 
3453  /* Use direct access to info_ptr here because otherwise the simplified API
3454  * would require PNG_EASY_ACCESS_SUPPORTED (just for this.) Note this is
3455  * checking the value after libpng expansions, not the original value in the
3456  * PNG.
3457  */
3458  switch (info_ptr->bit_depth)
3459  {
3460  case 8:
3461  /* 8-bit sRGB gray values with an alpha channel; the alpha channel is
3462  * to be removed by composing on a background: either the row if
3463  * display->background is NULL or display->background->green if not.
3464  * Unlike the code above ALPHA_OPTIMIZED has *not* been done.
3465  */
3466  {
3467  png_bytep first_row = png_voidcast(png_bytep, display->first_row);
3468  ptrdiff_t step_row = display->row_bytes;
3469 
3470  for (pass = 0; pass < passes; ++pass)
3471  {
3472  png_bytep row = png_voidcast(png_bytep, display->first_row);
3473  unsigned int startx, stepx, stepy;
3474  png_uint_32 y;
3475 
3476  if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3477  {
3478  /* The row may be empty for a short image: */
3479  if (PNG_PASS_COLS(width, pass) == 0)
3480  continue;
3481 
3482  startx = PNG_PASS_START_COL(pass);
3483  stepx = PNG_PASS_COL_OFFSET(pass);
3484  y = PNG_PASS_START_ROW(pass);
3485  stepy = PNG_PASS_ROW_OFFSET(pass);
3486  }
3487 
3488  else
3489  {
3490  y = 0;
3491  startx = 0;
3492  stepx = stepy = 1;
3493  }
3494 
3495  if (display->background == NULL)
3496  {
3497  for (; y<height; y += stepy)
3498  {
3500  display->local_row);
3501  png_bytep outrow = first_row + y * step_row;
3502  png_const_bytep end_row = outrow + width;
3503 
3504  /* Read the row, which is packed: */
3505  png_read_row(png_ptr, inrow, NULL);
3506 
3507  /* Now do the composition on each pixel in this row. */
3508  outrow += startx;
3509  for (; outrow < end_row; outrow += stepx)
3510  {
3511  png_byte alpha = inrow[1];
3512 
3513  if (alpha > 0) /* else no change to the output */
3514  {
3515  png_uint_32 component = inrow[0];
3516 
3517  if (alpha < 255) /* else just use component */
3518  {
3519  /* Since PNG_OPTIMIZED_ALPHA was not set it is
3520  * necessary to invert the sRGB transfer
3521  * function and multiply the alpha out.
3522  */
3523  component = png_sRGB_table[component] * alpha;
3524  component += png_sRGB_table[outrow[0]] *
3525  (255-alpha);
3526  component = PNG_sRGB_FROM_LINEAR(component);
3527  }
3528 
3529  outrow[0] = (png_byte)component;
3530  }
3531 
3532  inrow += 2; /* gray and alpha channel */
3533  }
3534  }
3535  }
3536 
3537  else /* constant background value */
3538  {
3539  png_byte background8 = display->background->green;
3540  png_uint_16 background = png_sRGB_table[background8];
3541 
3542  for (; y<height; y += stepy)
3543  {
3545  display->local_row);
3546  png_bytep outrow = first_row + y * step_row;
3547  png_const_bytep end_row = outrow + width;
3548 
3549  /* Read the row, which is packed: */
3550  png_read_row(png_ptr, inrow, NULL);
3551 
3552  /* Now do the composition on each pixel in this row. */
3553  outrow += startx;
3554  for (; outrow < end_row; outrow += stepx)
3555  {
3556  png_byte alpha = inrow[1];
3557 
3558  if (alpha > 0) /* else use background */
3559  {
3560  png_uint_32 component = inrow[0];
3561 
3562  if (alpha < 255) /* else just use component */
3563  {
3564  component = png_sRGB_table[component] * alpha;
3565  component += background * (255-alpha);
3566  component = PNG_sRGB_FROM_LINEAR(component);
3567  }
3568 
3569  outrow[0] = (png_byte)component;
3570  }
3571 
3572  else
3573  outrow[0] = background8;
3574 
3575  inrow += 2; /* gray and alpha channel */
3576  }
3577 
3578  row += display->row_bytes;
3579  }
3580  }
3581  }
3582  }
3583  break;
3584 
3585  case 16:
3586  /* 16-bit linear with pre-multiplied alpha; the pre-multiplication must
3587  * still be done and, maybe, the alpha channel removed. This code also
3588  * handles the alpha-first option.
3589  */
3590  {
3592  display->first_row);
3593  /* The division by two is safe because the caller passed in a
3594  * stride which was multiplied by 2 (below) to get row_bytes.
3595  */
3596  ptrdiff_t step_row = display->row_bytes / 2;
3597  unsigned int preserve_alpha = (image->format &
3598  PNG_FORMAT_FLAG_ALPHA) != 0;
3599  unsigned int outchannels = 1U+preserve_alpha;
3600  int swap_alpha = 0;
3601 
3602 # ifdef PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED
3603  if (preserve_alpha != 0 &&
3604  (image->format & PNG_FORMAT_FLAG_AFIRST) != 0)
3605  swap_alpha = 1;
3606 # endif
3607 
3608  for (pass = 0; pass < passes; ++pass)
3609  {
3610  unsigned int startx, stepx, stepy;
3611  png_uint_32 y;
3612 
3613  /* The 'x' start and step are adjusted to output components here.
3614  */
3615  if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3616  {
3617  /* The row may be empty for a short image: */
3618  if (PNG_PASS_COLS(width, pass) == 0)
3619  continue;
3620 
3621  startx = PNG_PASS_START_COL(pass) * outchannels;
3622  stepx = PNG_PASS_COL_OFFSET(pass) * outchannels;
3623  y = PNG_PASS_START_ROW(pass);
3624  stepy = PNG_PASS_ROW_OFFSET(pass);
3625  }
3626 
3627  else
3628  {
3629  y = 0;
3630  startx = 0;
3631  stepx = outchannels;
3632  stepy = 1;
3633  }
3634 
3635  for (; y<height; y += stepy)
3636  {
3637  png_const_uint_16p inrow;
3638  png_uint_16p outrow = first_row + y*step_row;
3639  png_uint_16p end_row = outrow + width * outchannels;
3640 
3641  /* Read the row, which is packed: */
3643  display->local_row), NULL);
3644  inrow = png_voidcast(png_const_uint_16p, display->local_row);
3645 
3646  /* Now do the pre-multiplication on each pixel in this row.
3647  */
3648  outrow += startx;
3649  for (; outrow < end_row; outrow += stepx)
3650  {
3651  png_uint_32 component = inrow[0];
3652  png_uint_16 alpha = inrow[1];
3653 
3654  if (alpha > 0) /* else 0 */
3655  {
3656  if (alpha < 65535) /* else just use component */
3657  {
3658  component *= alpha;
3659  component += 32767;
3660  component /= 65535;
3661  }
3662  }
3663 
3664  else
3665  component = 0;
3666 
3667  outrow[swap_alpha] = (png_uint_16)component;
3668  if (preserve_alpha != 0)
3669  outrow[1 ^ swap_alpha] = alpha;
3670 
3671  inrow += 2; /* components and alpha channel */
3672  }
3673  }
3674  }
3675  }
3676  break;
3677 
3678 #ifdef __GNUC__
3679  default:
3680  png_error(png_ptr, "unexpected bit depth");
3681 #endif
3682  }
3683 
3684  return 1;
3685 }
3686 
3687 /* The guts of png_image_finish_read as a png_safe_execute callback. */
3688 static int
3690 {
3692  argument);
3693  png_imagep image = display->image;
3694  png_structrp png_ptr = image->opaque->png_ptr;
3695  png_inforp info_ptr = image->opaque->info_ptr;
3696 
3697  png_uint_32 format = image->format;
3698  int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0;
3699  int do_local_compose = 0;
3700  int do_local_background = 0; /* to avoid double gamma correction bug */
3701  int passes = 0;
3702 
3703  /* Add transforms to ensure the correct output format is produced then check
3704  * that the required implementation support is there. Always expand; always
3705  * need 8 bits minimum, no palette and expanded tRNS.
3706  */
3707  png_set_expand(png_ptr);
3708 
3709  /* Now check the format to see if it was modified. */
3710  {
3711  png_uint_32 base_format = png_image_format(png_ptr) &
3712  ~PNG_FORMAT_FLAG_COLORMAP /* removed by png_set_expand */;
3713  png_uint_32 change = format ^ base_format;
3714  png_fixed_point output_gamma;
3715  int mode; /* alpha mode */
3716 
3717  /* Do this first so that we have a record if rgb to gray is happening. */
3718  if ((change & PNG_FORMAT_FLAG_COLOR) != 0)
3719  {
3720  /* gray<->color transformation required. */
3721  if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
3722  png_set_gray_to_rgb(png_ptr);
3723 
3724  else
3725  {
3726  /* libpng can't do both rgb to gray and
3727  * background/pre-multiplication if there is also significant gamma
3728  * correction, because both operations require linear colors and
3729  * the code only supports one transform doing the gamma correction.
3730  * Handle this by doing the pre-multiplication or background
3731  * operation in this code, if necessary.
3732  *
3733  * TODO: fix this by rewriting pngrtran.c (!)
3734  *
3735  * For the moment (given that fixing this in pngrtran.c is an
3736  * enormous change) 'do_local_background' is used to indicate that
3737  * the problem exists.
3738  */
3739  if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3740  do_local_background = 1/*maybe*/;
3741 
3744  }
3745 
3746  change &= ~PNG_FORMAT_FLAG_COLOR;
3747  }
3748 
3749  /* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise.
3750  */
3751  {
3752  png_fixed_point input_gamma_default;
3753 
3754  if ((base_format & PNG_FORMAT_FLAG_LINEAR) != 0 &&
3755  (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
3756  input_gamma_default = PNG_GAMMA_LINEAR;
3757  else
3758  input_gamma_default = PNG_DEFAULT_sRGB;
3759 
3760  /* Call png_set_alpha_mode to set the default for the input gamma; the
3761  * output gamma is set by a second call below.
3762  */
3763  png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, input_gamma_default);
3764  }
3765 
3766  if (linear != 0)
3767  {
3768  /* If there *is* an alpha channel in the input it must be multiplied
3769  * out; use PNG_ALPHA_STANDARD, otherwise just use PNG_ALPHA_PNG.
3770  */
3771  if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3772  mode = PNG_ALPHA_STANDARD; /* associated alpha */
3773 
3774  else
3775  mode = PNG_ALPHA_PNG;
3776 
3777  output_gamma = PNG_GAMMA_LINEAR;
3778  }
3779 
3780  else
3781  {
3782  mode = PNG_ALPHA_PNG;
3783  output_gamma = PNG_DEFAULT_sRGB;
3784  }
3785 
3786  /* If 'do_local_background' is set check for the presence of gamma
3787  * correction; this is part of the work-round for the libpng bug
3788  * described above.
3789  *
3790  * TODO: fix libpng and remove this.
3791  */
3792  if (do_local_background != 0)
3793  {
3794  png_fixed_point gtest;
3795 
3796  /* This is 'png_gamma_threshold' from pngrtran.c; the test used for
3797  * gamma correction, the screen gamma hasn't been set on png_struct
3798  * yet; it's set below. png_struct::gamma, however, is set to the
3799  * final value.
3800  */
3801  if (png_muldiv(&gtest, output_gamma, png_ptr->colorspace.gamma,
3802  PNG_FP_1) != 0 && png_gamma_significant(gtest) == 0)
3803  do_local_background = 0;
3804 
3805  else if (mode == PNG_ALPHA_STANDARD)
3806  {
3807  do_local_background = 2/*required*/;
3808  mode = PNG_ALPHA_PNG; /* prevent libpng doing it */
3809  }
3810 
3811  /* else leave as 1 for the checks below */
3812  }
3813 
3814  /* If the bit-depth changes then handle that here. */
3815  if ((change & PNG_FORMAT_FLAG_LINEAR) != 0)
3816  {
3817  if (linear != 0 /*16-bit output*/)
3818  png_set_expand_16(png_ptr);
3819 
3820  else /* 8-bit output */
3821  png_set_scale_16(png_ptr);
3822 
3823  change &= ~PNG_FORMAT_FLAG_LINEAR;
3824  }
3825 
3826  /* Now the background/alpha channel changes. */
3827  if ((change & PNG_FORMAT_FLAG_ALPHA) != 0)
3828  {
3829  /* Removing an alpha channel requires composition for the 8-bit
3830  * formats; for the 16-bit it is already done, above, by the
3831  * pre-multiplication and the channel just needs to be stripped.
3832  */
3833  if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3834  {
3835  /* If RGB->gray is happening the alpha channel must be left and the
3836  * operation completed locally.
3837  *
3838  * TODO: fix libpng and remove this.
3839  */
3840  if (do_local_background != 0)
3841  do_local_background = 2/*required*/;
3842 
3843  /* 16-bit output: just remove the channel */
3844  else if (linear != 0) /* compose on black (well, pre-multiply) */
3845  png_set_strip_alpha(png_ptr);
3846 
3847  /* 8-bit output: do an appropriate compose */
3848  else if (display->background != NULL)
3849  {
3850  png_color_16 c;
3851 
3852  c.index = 0; /*unused*/
3853  c.red = display->background->red;
3854  c.green = display->background->green;
3855  c.blue = display->background->blue;
3856  c.gray = display->background->green;
3857 
3858  /* This is always an 8-bit sRGB value, using the 'green' channel
3859  * for gray is much better than calculating the luminance here;
3860  * we can get off-by-one errors in that calculation relative to
3861  * the app expectations and that will show up in transparent
3862  * pixels.
3863  */
3864  png_set_background_fixed(png_ptr, &c,
3865  PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
3866  0/*gamma: not used*/);
3867  }
3868 
3869  else /* compose on row: implemented below. */
3870  {
3871  do_local_compose = 1;
3872  /* This leaves the alpha channel in the output, so it has to be
3873  * removed by the code below. Set the encoding to the 'OPTIMIZE'
3874  * one so the code only has to hack on the pixels that require
3875  * composition.
3876  */
3877  mode = PNG_ALPHA_OPTIMIZED;
3878  }
3879  }
3880 
3881  else /* output needs an alpha channel */
3882  {
3883  /* This is tricky because it happens before the swap operation has
3884  * been accomplished; however, the swap does *not* swap the added
3885  * alpha channel (weird API), so it must be added in the correct
3886  * place.
3887  */
3888  png_uint_32 filler; /* opaque filler */
3889  int where;
3890 
3891  if (linear != 0)
3892  filler = 65535;
3893 
3894  else
3895  filler = 255;
3896 
3897 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
3898  if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
3899  {
3900  where = PNG_FILLER_BEFORE;
3901  change &= ~PNG_FORMAT_FLAG_AFIRST;
3902  }
3903 
3904  else
3905 #endif
3906  where = PNG_FILLER_AFTER;
3907 
3908  png_set_add_alpha(png_ptr, filler, where);
3909  }
3910 
3911  /* This stops the (irrelevant) call to swap_alpha below. */
3912  change &= ~PNG_FORMAT_FLAG_ALPHA;
3913  }
3914 
3915  /* Now set the alpha mode correctly; this is always done, even if there is
3916  * no alpha channel in either the input or the output because it correctly
3917  * sets the output gamma.
3918  */
3919  png_set_alpha_mode_fixed(png_ptr, mode, output_gamma);
3920 
3921 # ifdef PNG_FORMAT_BGR_SUPPORTED
3922  if ((change & PNG_FORMAT_FLAG_BGR) != 0)
3923  {
3924  /* Check only the output format; PNG is never BGR; don't do this if
3925  * the output is gray, but fix up the 'format' value in that case.
3926  */
3927  if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
3928  png_set_bgr(png_ptr);
3929 
3930  else
3931  format &= ~PNG_FORMAT_FLAG_BGR;
3932 
3933  change &= ~PNG_FORMAT_FLAG_BGR;
3934  }
3935 # endif
3936 
3937 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
3938  if ((change & PNG_FORMAT_FLAG_AFIRST) != 0)
3939  {
3940  /* Only relevant if there is an alpha channel - it's particularly
3941  * important to handle this correctly because do_local_compose may
3942  * be set above and then libpng will keep the alpha channel for this
3943  * code to remove.
3944  */
3945  if ((format & PNG_FORMAT_FLAG_ALPHA) != 0)
3946  {
3947  /* Disable this if doing a local background,
3948  * TODO: remove this when local background is no longer required.
3949  */
3950  if (do_local_background != 2)
3951  png_set_swap_alpha(png_ptr);
3952  }
3953 
3954  else
3955  format &= ~PNG_FORMAT_FLAG_AFIRST;
3956 
3957  change &= ~PNG_FORMAT_FLAG_AFIRST;
3958  }
3959 # endif
3960 
3961  /* If the *output* is 16-bit then we need to check for a byte-swap on this
3962  * architecture.
3963  */
3964  if (linear != 0)
3965  {
3966  PNG_CONST png_uint_16 le = 0x0001;
3967 
3968  if ((*(png_const_bytep) & le) != 0)
3969  png_set_swap(png_ptr);
3970  }
3971 
3972  /* If change is not now 0 some transformation is missing - error out. */
3973  if (change != 0)
3974  png_error(png_ptr, "png_read_image: unsupported transformation");
3975  }
3976 
3977  PNG_SKIP_CHUNKS(png_ptr);
3978 
3979  /* Update the 'info' structure and make sure the result is as required; first
3980  * make sure to turn on the interlace handling if it will be required
3981  * (because it can't be turned on *after* the call to png_read_update_info!)
3982  *
3983  * TODO: remove the do_local_background fixup below.
3984  */
3985  if (do_local_compose == 0 && do_local_background != 2)
3986  passes = png_set_interlace_handling(png_ptr);
3987 
3988  png_read_update_info(png_ptr, info_ptr);
3989 
3990  {
3991  png_uint_32 info_format = 0;
3992 
3993  if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
3994  info_format |= PNG_FORMAT_FLAG_COLOR;
3995 
3996  if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
3997  {
3998  /* do_local_compose removes this channel below. */
3999  if (do_local_compose == 0)
4000  {
4001  /* do_local_background does the same if required. */
4002  if (do_local_background != 2 ||
4003  (format & PNG_FORMAT_FLAG_ALPHA) != 0)
4004  info_format |= PNG_FORMAT_FLAG_ALPHA;
4005  }
4006  }
4007 
4008  else if (do_local_compose != 0) /* internal error */
4009  png_error(png_ptr, "png_image_read: alpha channel lost");
4010 
4011  if (info_ptr->bit_depth == 16)
4012  info_format |= PNG_FORMAT_FLAG_LINEAR;
4013 
4014 #ifdef PNG_FORMAT_BGR_SUPPORTED
4015  if ((png_ptr->transformations & PNG_BGR) != 0)
4016  info_format |= PNG_FORMAT_FLAG_BGR;
4017 #endif
4018 
4019 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
4020  if (do_local_background == 2)
4021  {
4022  if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
4023  info_format |= PNG_FORMAT_FLAG_AFIRST;
4024  }
4025 
4026  if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0 ||
4027  ((png_ptr->transformations & PNG_ADD_ALPHA) != 0 &&
4028  (png_ptr->flags & PNG_FLAG_FILLER_AFTER) == 0))
4029  {
4030  if (do_local_background == 2)
4031  png_error(png_ptr, "unexpected alpha swap transformation");
4032 
4033  info_format |= PNG_FORMAT_FLAG_AFIRST;
4034  }
4035 # endif
4036 
4037  /* This is actually an internal error. */
4038  if (info_format != format)
4039  png_error(png_ptr, "png_read_image: invalid transformations");
4040  }
4041 
4042  /* Now read the rows. If do_local_compose is set then it is necessary to use
4043  * a local row buffer. The output will be GA, RGBA or BGRA and must be
4044  * converted to G, RGB or BGR as appropriate. The 'local_row' member of the
4045  * display acts as a flag.
4046  */
4047  {
4048  png_voidp first_row = display->buffer;
4049  ptrdiff_t row_bytes = display->row_stride;
4050 
4051  if (linear != 0)
4052  row_bytes *= 2;
4053 
4054  /* The following expression is designed to work correctly whether it gives
4055  * a signed or an unsigned result.
4056  */
4057  if (row_bytes < 0)
4058  {
4059  char *ptr = png_voidcast(char*, first_row);
4060  ptr += (image->height-1) * (-row_bytes);
4061  first_row = png_voidcast(png_voidp, ptr);
4062  }
4063 
4064  display->first_row = first_row;
4065  display->row_bytes = row_bytes;
4066  }
4067 
4068  if (do_local_compose != 0)
4069  {
4070  int result;
4071  png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
4072 
4073  display->local_row = row;
4074  result = png_safe_execute(image, png_image_read_composite, display);
4075  display->local_row = NULL;
4076  png_free(png_ptr, row);
4077 
4078  return result;
4079  }
4080 
4081  else if (do_local_background == 2)
4082  {
4083  int result;
4084  png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
4085 
4086  display->local_row = row;
4087  result = png_safe_execute(image, png_image_read_background, display);
4088  display->local_row = NULL;
4089  png_free(png_ptr, row);
4090 
4091  return result;
4092  }
4093 
4094  else
4095  {
4096  png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes;
4097 
4098  while (--passes >= 0)
4099  {
4100  png_uint_32 y = image->height;
4101  png_bytep row = png_voidcast(png_bytep, display->first_row);
4102 
4103  for (; y > 0; --y)
4104  {
4105  png_read_row(png_ptr, row, NULL);
4106  row += row_bytes;
4107  }
4108  }
4109 
4110  return 1;
4111  }
4112 }
4113 
4114 int PNGAPI
4115 png_image_finish_read(png_imagep image, png_const_colorp background,
4116  void *buffer, png_int_32 row_stride, void *colormap)
4117 {
4118  if (image != NULL && image->version == PNG_IMAGE_VERSION)
4119  {
4120  /* Check for row_stride overflow. This check is not performed on the
4121  * original PNG format because it may not occur in the output PNG format
4122  * and libpng deals with the issues of reading the original.
4123  */
4124  const unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
4125 
4126  /* The following checks just the 'row_stride' calculation to ensure it
4127  * fits in a signed 32-bit value. Because channels/components can be
4128  * either 1 or 2 bytes in size the length of a row can still overflow 32
4129  * bits; this is just to verify that the 'row_stride' argument can be
4130  * represented.
4131  */
4132  if (image->width <= 0x7fffffffU/channels) /* no overflow */
4133  {
4134  png_uint_32 check;
4135  const png_uint_32 png_row_stride = image->width * channels;
4136 
4137  if (row_stride == 0)
4138  row_stride = (png_int_32)/*SAFE*/png_row_stride;
4139 
4140  if (row_stride < 0)
4141  check = (png_uint_32)(-row_stride);
4142 
4143  else
4144  check = (png_uint_32)row_stride;
4145 
4146  /* This verifies 'check', the absolute value of the actual stride
4147  * passed in and detects overflow in the application calculation (i.e.
4148  * if the app did actually pass in a non-zero 'row_stride'.
4149  */
4150  if (image->opaque != NULL && buffer != NULL && check >= png_row_stride)
4151  {
4152  /* Now check for overflow of the image buffer calculation; this
4153  * limits the whole image size to 32 bits for API compatibility with
4154  * the current, 32-bit, PNG_IMAGE_BUFFER_SIZE macro.
4155  *
4156  * The PNG_IMAGE_BUFFER_SIZE macro is:
4157  *
4158  * (PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)*height*(row_stride))
4159  *
4160  * And the component size is always 1 or 2, so make sure that the
4161  * number of *bytes* that the application is saying are available
4162  * does actually fit into a 32-bit number.
4163  *
4164  * NOTE: this will be changed in 1.7 because PNG_IMAGE_BUFFER_SIZE
4165  * will be changed to use png_alloc_size_t; bigger images can be
4166  * accomodated on 64-bit systems.
4167  */
4168  if (image->height <=
4169  0xffffffffU/PNG_IMAGE_PIXEL_COMPONENT_SIZE(image->format)/check)
4170  {
4171  if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 ||
4172  (image->colormap_entries > 0 && colormap != NULL))
4173  {
4174  int result;
4175  png_image_read_control display;
4176 
4177  memset(&display, 0, (sizeof display));
4178  display.image = image;
4179  display.buffer = buffer;
4180  display.row_stride = row_stride;
4181  display.colormap = colormap;
4182  display.background = background;
4183  display.local_row = NULL;
4184 
4185  /* Choose the correct 'end' routine; for the color-map case
4186  * all the setup has already been done.
4187  */
4188  if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0)
4189  result =
4190  png_safe_execute(image,
4191  png_image_read_colormap, &display) &&
4192  png_safe_execute(image,
4193  png_image_read_colormapped, &display);
4194 
4195  else
4196  result =
4197  png_safe_execute(image,
4198  png_image_read_direct, &display);
4199 
4200  png_image_free(image);
4201  return result;
4202  }
4203 
4204  else
4205  return png_image_error(image,
4206  "png_image_finish_read[color-map]: no color-map");
4207  }
4208 
4209  else
4210  return png_image_error(image,
4211  "png_image_finish_read: image too large");
4212  }
4213 
4214  else
4215  return png_image_error(image,
4216  "png_image_finish_read: invalid argument");
4217  }
4218 
4219  else
4220  return png_image_error(image,
4221  "png_image_finish_read: row_stride too large");
4222  }
4223 
4224  else if (image != NULL)
4225  return png_image_error(image,
4226  "png_image_finish_read: damaged PNG_IMAGE_VERSION");
4227 
4228  return 0;
4229 }
4230 
4231 #endif /* SIMPLIFIED_READ */
4232 #endif /* READ */
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Definition: pngpriv.h:633
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Definition: pngread.c:277
png_read_image
void png_read_image(png_structrp png_ptr, png_bytepp image)
Definition: pngread.c:723
png_tEXt
#define png_tEXt
Definition: pngpriv.h:862
png_handle_tIME
void png_handle_tIME(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
Definition: pngrutil.c:2459
PNG_HAVE_CHUNK_AFTER_IDAT
#define PNG_HAVE_CHUNK_AFTER_IDAT
Definition: pngpriv.h:628
PNG_INTRAPIXEL_DIFFERENCING
#define PNG_INTRAPIXEL_DIFFERENCING
Definition: png.h:714
png_read_sig
void png_read_sig(png_structrp png_ptr, png_inforp info_ptr)
Definition: pngrutil.c:121
png_struct_def::free_me
png_uint_32 free_me
Definition: pngstruct.h:368
png_image_read_colormapped
static int png_image_read_colormapped(png_voidp argument)
Definition: pngread.c:3150
png_voidcast
#define png_voidcast(type, value)
Definition: pngpriv.h:485
png_image_read_control::local_row
png_voidp local_row
Definition: pngread.c:1309
png_info_def::valid
png_uint_32 valid
Definition: pnginfo.h:60
png_row_info_struct::width
png_uint_32 width
Definition: png.h:787
png_struct_def::chunk_name
png_uint_32 chunk_name
Definition: pngstruct.h:220
png_handle_bKGD
void png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
Definition: pngrutil.c:1929
png_image_begin_read_from_file
int png_image_begin_read_from_file(png_imagep image, const char *file_name)
Definition: pngread.c:1519
png_handle_gAMA
void png_handle_gAMA(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
Definition: pngrutil.c:1119
png_image_read_control::row_bytes
ptrdiff_t row_bytes
Definition: pngread.c:1311
png_IEND
#define png_IEND
Definition: pngpriv.h:840
png_safe_execute
int png_safe_execute(png_imagep image, int(*function)(png_voidp), png_voidp arg)
png_sPLT
#define png_sPLT
Definition: pngpriv.h:859
width
static png_uint_32 width
Definition: pngcrush.c:2136
PNG_ALLOCATED
#define PNG_ALLOCATED
Definition: pngconf.h:445
png_set_benign_errors
PNG_IMPEXP void() png_set_benign_errors(png_structrp png_ptr, int allowed)
Definition: pngset.c:1671
png_set_tRNS_to_alpha
PNG_IMPEXP void() png_set_tRNS_to_alpha(png_structrp png_ptr)
Definition: pngrtran.c:913
PNG_COLOR_TYPE_RGB
#define PNG_COLOR_TYPE_RGB
Definition: png.h:701
png_read_end
void png_read_end(png_structrp png_ptr, png_inforp info_ptr)
Definition: pngread.c:789
PNG_FLAG_MNG_FILTER_64
#define PNG_FLAG_MNG_FILTER_64
Definition: png.h:889
png_struct_def::big_row_buf
png_bytep big_row_buf
Definition: pngstruct.h:416
PNG_TRANSFORM_PACKSWAP
#define PNG_TRANSFORM_PACKSWAP
Definition: png.h:867
png_struct_def::prev_row
png_bytep prev_row
Definition: pngstruct.h:221
output_format
static int output_format
Definition: pngcrush.c:2365
PNG_SWAP_BYTES
#define PNG_SWAP_BYTES
Definition: pngpriv.h:637
png_set_rgb_to_gray_fixed
PNG_IMPEXP void() png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action, png_fixed_point red, png_fixed_point green)
Definition: pngrtran.c:957
PNG_CMAP_NONE
#define PNG_CMAP_NONE
Definition: pngread.c:1287
PNG_DIV51
#define PNG_DIV51(v8)
Definition: pngread.c:1679
PNG_CONST
#define PNG_CONST
Definition: pngconf.h:70
PNG_TRANSFORM_STRIP_16
#define PNG_TRANSFORM_STRIP_16
Definition: png.h:864
png_handle_sRGB
void png_handle_sRGB(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
Definition: pngrutil.c:1311
png_set_invert_mono
void png_set_invert_mono(png_structrp png_ptr)
Definition: pngtrans.c:250
PNGAPI
#define PNGAPI
Definition: pngconf.h:267
PNG_FILLER
#define PNG_FILLER
Definition: pngcrush.c:1991
png_info_def::bit_depth
png_byte bit_depth
Definition: pnginfo.h:65
png_set_shift
PNG_IMPEXP void() png_set_shift(png_structrp png_ptr, png_const_color_8p true_bits)
Definition: pngtrans.c:84
PNGCRUSH_TIMER_VOID_API
#define PNGCRUSH_TIMER_VOID_API
Definition: pngcrush.c:1518
PNG_TRANSFORM_EXPAND_16
#define PNG_TRANSFORM_EXPAND_16
Definition: png.h:882
make_ga_colormap
static int make_ga_colormap(png_image_read_control *display)
Definition: pngread.c:2023
png_start_read_image
void png_start_read_image(png_structrp png_ptr)
Definition: pngread.c:308
PNG_SKIP_CHUNKS
#define PNG_SKIP_CHUNKS(p)
Definition: pngread.c:1670
PNG_PASS_ROW_OFFSET
#define PNG_PASS_ROW_OFFSET(pass)
Definition: png.h:2482
png_const_uint_16p
const typedef png_uint_16 * png_const_uint_16p
Definition: pngconf.h:591
PNG_HAVE_IHDR
#define PNG_HAVE_IHDR
Definition: png.h:675
PNG_PACKSWAP
#define PNG_PACKSWAP
Definition: pngpriv.h:649
png_read_info
void png_read_info(png_structrp png_ptr, png_inforp info_ptr)
Definition: pngread.c:102
PNG_HAVE_IDAT
#define PNG_HAVE_IDAT
Definition: pngpriv.h:617
png_image_read_header
static int png_image_read_header(png_voidp argument)
Definition: pngread.c:1424
png_image_read_control::background
png_const_colorp background
Definition: pngread.c:1307
png_get_rowbytes
PNG_IMPEXP png_size_t() png_get_rowbytes(png_const_structrp png_ptr, png_const_inforp info_ptr)
Definition: pngget.c:30
png_handle_tRNS
void png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
Definition: pngrutil.c:1825
png_safe_error
void() png_safe_error(png_structp png_ptr, png_const_charp error_message)
png_struct_def::row_buf
png_bytep row_buf
Definition: pngstruct.h:226
png_error_ptr
void(* png_error_ptr)(png_structp, png_const_charp)
Definition: png.h:806
png_gamma_not_sRGB
static int png_gamma_not_sRGB(png_fixed_point g)
Definition: pngread.c:1405
PNG_PASS_START_COL
#define PNG_PASS_START_COL(pass)
Definition: png.h:2475
png_set_expand_16
PNG_IMPEXP void() png_set_expand_16(png_structrp png_ptr)
Definition: pngrtran.c:929
png_handle_oFFs
void png_handle_oFFs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
Definition: pngrutil.c:2190
png_handle_tEXt
void png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
Definition: pngrutil.c:2505
png_read_row
void png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)
Definition: pngread.c:393
P_FILE
#define P_FILE
Definition: pngread.c:1281
png_malloc
PNG_IMPEXP png_voidp() png_malloc(png_const_structrp png_ptr, png_alloc_size_t size)
Definition: pngmem.c:172
png_info_def
Definition: pnginfo.h:55
png_row_info_struct::channels
png_byte channels
Definition: png.h:791
png_set_packswap
PNG_IMPEXP void() png_set_packswap(png_structrp png_ptr)
Definition: pngtrans.c:70
png_struct_def::palette
png_colorp palette
Definition: pngstruct.h:239
PNG_FREE_PLTE
#define PNG_FREE_PLTE
Definition: png.h:1789
PNG_TRANSFORM_INVERT_ALPHA
#define PNG_TRANSFORM_INVERT_ALPHA
Definition: png.h:874
png_color_16_struct::green
png_uint_16 green
Definition: png.h:523
PNG_COLOR_TYPE_GRAY
#define PNG_COLOR_TYPE_GRAY
Definition: png.h:699
png_row_info_struct::color_type
png_byte color_type
Definition: png.h:789
PNG_HANDLE_CHUNK_NEVER
#define PNG_HANDLE_CHUNK_NEVER
Definition: png.h:2377
png_image_begin_read_from_memory
int png_image_begin_read_from_memory(png_imagep image, png_const_voidp memory, png_size_t size)
Definition: pngread.c:1587
PNG_INTERLACE_ADAM7_PASSES
#define PNG_INTERLACE_ADAM7_PASSES
Definition: png.h:2468
png_info_def::rowbytes
png_size_t rowbytes
Definition: pnginfo.h:61
png_struct_def::num_palette
png_uint_16 num_palette
Definition: pngstruct.h:240
png_debug
#define png_debug(l, m)
Definition: pngdebug.h:145
PNG_TRANSFORM_PACKING
#define PNG_TRANSFORM_PACKING
Definition: png.h:866
png_image_read_control::row_stride
png_int_32 row_stride
Definition: pngread.c:1305
PNG_INTERLACE
#define PNG_INTERLACE
Definition: pngpriv.h:634
voidp
Byte * voidp
Definition: zconf.h:414
png_IDAT
#define png_IDAT
Definition: pngpriv.h:839
png_muldiv
int png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times, png_int_32 divisor)
Definition: png.c:3355
png_create_info_struct
png_infop png_create_info_struct(png_const_structrp png_ptr)
Definition: png.c:354
png_const_charp
const typedef char * png_const_charp
Definition: pngconf.h:595
make_rgb_colormap
static int make_rgb_colormap(png_image_read_control *display)
Definition: pngread.c:2078
PNG_FILTER_VALUE_NONE
#define PNG_FILTER_VALUE_NONE
Definition: png.h:1507
png_IHDR
#define png_IHDR
Definition: pngpriv.h:841
png_set_background_fixed
PNG_IMPEXP void() png_set_background_fixed(png_structrp png_ptr, png_const_color_16p background_color, int background_gamma_code, int need_expand, png_fixed_point background_gamma)
Definition: pngrtran.c:126
png_cHRM
#define png_cHRM
Definition: pngpriv.h:844
pngcrush_timer_start
void pngcrush_timer_start(unsigned int n)
Definition: pngcrush.c:1587
buffer
char buffer[256]
Definition: pngcrush.c:2214
png_colormap_compose
static png_uint_32 png_colormap_compose(png_image_read_control *display, png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha, png_uint_32 background, int encoding)
Definition: pngread.c:1742
PNG_FILTER_VALUE_LAST
#define PNG_FILTER_VALUE_LAST
Definition: png.h:1512
png_struct_def::flags
png_uint_32 flags
Definition: pngstruct.h:179
PNG_HANDLE_CHUNK_AS_DEFAULT
#define PNG_HANDLE_CHUNK_AS_DEFAULT
Definition: png.h:2376
png_gamma_16bit_correct
png_uint_16 png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val)
Definition: png.c:3918
png_handle_sBIT
void png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
Definition: pngrutil.c:1157
PNG_PASS_START_ROW
#define PNG_PASS_START_ROW(pass)
Definition: png.h:2474
png_image_finish_read
int png_image_finish_read(png_imagep image, png_const_colorp background, void *buffer, png_int_32 row_stride, void *colormap)
Definition: pngread.c:4115
PNG_HAVE_IEND
#define PNG_HAVE_IEND
Definition: pngpriv.h:619
PNG_CMAP_TRANS
#define PNG_CMAP_TRANS
Definition: pngread.c:1289
png_image_read_and_map
static int png_image_read_and_map(png_voidp argument)
Definition: pngread.c:2961
png_row_info_struct::pixel_depth
png_byte pixel_depth
Definition: png.h:792
png_image_read_control::gamma_to_linear
png_fixed_point gamma_to_linear
Definition: pngread.c:1313
PNG_INTERLACE_ADAM7
#define PNG_INTERLACE_ADAM7
Definition: png.h:719
PNG_TRANSFORM_BGR
#define PNG_TRANSFORM_BGR
Definition: png.h:871
set_file_encoding
static void set_file_encoding(png_image_read_control *display)
Definition: pngread.c:1683
PNG_PASS_COL_OFFSET
#define PNG_PASS_COL_OFFSET(pass)
Definition: png.h:2483
png_image_format
static png_uint_32 png_image_format(png_structrp png_ptr)
Definition: pngread.c:1372
png_image_error
int png_image_error(png_imagep image, png_const_charp error_message)
png_read_transform_info
void png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
Definition: pngrtran.c:1927
PNG_ADD_ALPHA
#define PNG_ADD_ALPHA
Definition: pngpriv.h:658
PNG_FILLER_BEFORE
#define PNG_FILLER_BEFORE
Definition: png.h:1279
P_LINEAR
#define P_LINEAR
Definition: pngread.c:1280
png_struct_def
Definition: pngstruct.h:143
png_set_swap_alpha
void png_set_swap_alpha(png_structrp png_ptr)
Definition: pngtrans.c:223
png_image_read_control
Definition: pngread.c:1300
png_image_read_control::colormap
png_voidp colormap
Definition: pngread.c:1306
png_struct_def::big_prev_row
png_bytep big_prev_row
Definition: pngstruct.h:471
png_struct_def::read_row_fn
png_read_status_ptr read_row_fn
Definition: pngstruct.h:319
png_const_voidp
const typedef void * png_const_voidp
Definition: pngconf.h:583
height
static png_uint_32 height
Definition: pngcrush.c:2136
png_create_read_struct_2
png_structp png_create_read_struct_2(png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn)
Definition: pngread.c:53
png_info_def::free_me
png_uint_32 free_me
Definition: pnginfo.h:228
png_image_read_composite
static int png_image_read_composite(png_voidp argument)
Definition: pngread.c:3282
inflateEnd
int inflateEnd(z_streamp strm)
Definition: inflate.c:1277
png_read_status_ptr
void(* png_read_status_ptr)(png_structp, png_uint_32, int)
Definition: png.h:810
decode_gamma
static unsigned int decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding)
Definition: pngread.c:1703
png_handle_sPLT
void png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
Definition: pngrutil.c:1648
png_sRGB_table
const png_uint_16 png_sRGB_table[256]
png_uint_16p
png_uint_16 * png_uint_16p
Definition: pngconf.h:590
png_struct_def::io_ptr
png_voidp io_ptr
Definition: pngstruct.h:158
png_hIST
#define png_hIST
Definition: pngpriv.h:851
png_struct_def::num_rows
png_uint_32 num_rows
Definition: pngstruct.h:215
PNG_BACKGROUND_GAMMA_SCREEN
#define PNG_BACKGROUND_GAMMA_SCREEN
Definition: png.h:1339
png_oFFs
#define png_oFFs
Definition: pngpriv.h:854
PNG_LIBPNG_VER_STRING
#define PNG_LIBPNG_VER_STRING
Definition: png.h:312
png_struct_def::pixel_depth
png_byte pixel_depth
Definition: pngstruct.h:256
png_read_start_row
void png_read_start_row(png_structrp png_ptr)
Definition: pngrutil.c:4378
png_set_strip_alpha
PNG_IMPEXP void() png_set_strip_alpha(png_structrp png_ptr)
Definition: pngrtran.c:199
png_struct_def::maximum_pixel_depth
png_byte maximum_pixel_depth
Definition: pngstruct.h:262
png_handle_iTXt
void png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
Definition: pngrutil.c:2703
png_struct_def::idat_size
png_uint_32 idat_size
Definition: pngstruct.h:237
png_row_info_struct::rowbytes
png_size_t rowbytes
Definition: png.h:788
PNG_ERROR_ACTION_NONE
#define PNG_ERROR_ACTION_NONE
Definition: png.h:1107
PNG_FLAG_BENIGN_ERRORS_WARN
#define PNG_FLAG_BENIGN_ERRORS_WARN
Definition: pngpriv.h:690
png_warning
PNG_IMPEXP void() png_warning(png_const_structrp png_ptr, png_const_charp warning_message)
Definition: pngerror.c:216
png_image_begin_read_from_stdio
int png_image_begin_read_from_stdio(png_imagep image, FILE *file)
Definition: pngread.c:1489
png_set_expand
PNG_IMPEXP void() png_set_expand(png_structrp png_ptr)
Definition: pngrtran.c:859
png_malloc_ptr
png_voidp(* png_malloc_ptr)(png_structp, png_alloc_size_t)
Definition: png.h:899
png_image_memory_read
static void png_image_memory_read(png_structp png_ptr, png_bytep out, png_size_t need)
Definition: pngread.c:1558
png_chunk_error
PNG_IMPEXP void() png_chunk_error(png_const_structrp png_ptr, png_const_charp error_message)
Definition: pngerror.c:481
png_destroy_png_struct
void png_destroy_png_struct(png_structrp png_ptr)
Definition: pngmem.c:25
PNG_SHIFT
#define PNG_SHIFT
Definition: pngpriv.h:636
png_size_t
size_t png_size_t
Definition: pngconf.h:527
png_color_16_struct::index
png_byte index
Definition: png.h:521
PNG_GA_COLORMAP_ENTRIES
#define PNG_GA_COLORMAP_ENTRIES
Definition: pngread.c:2075
png_pHYs
#define png_pHYs
Definition: pngpriv.h:856
PNG_CMAP_RGB_ALPHA
#define PNG_CMAP_RGB_ALPHA
Definition: pngread.c:1291
PNG_ROWBYTES
#define PNG_ROWBYTES(pixel_bits, width)
Definition: pngpriv.h:729
png_struct_def::channels
png_byte channels
Definition: pngstruct.h:257
png_struct_def::bit_depth
png_byte bit_depth
Definition: pngstruct.h:254
png_read_finish_IDAT
void png_read_finish_IDAT(png_structrp png_ptr)
Definition: pngrutil.c:4265
PNG_FLAG_FILLER_AFTER
#define PNG_FLAG_FILLER_AFTER
Definition: pngpriv.h:677
PNG_TRANSFORM_GRAY_TO_RGB
#define PNG_TRANSFORM_GRAY_TO_RGB
Definition: png.h:880
PNG_CMAP_NONE_BACKGROUND
#define PNG_CMAP_NONE_BACKGROUND
Definition: pngread.c:1294
png_sBIT
#define png_sBIT
Definition: pngpriv.h:857
PNG_COLOR_MASK_COLOR
#define PNG_COLOR_MASK_COLOR
Definition: png.h:695
PNG_TRANSFORM_SWAP_ALPHA
#define PNG_TRANSFORM_SWAP_ALPHA
Definition: png.h:872
png_malloc_warn
PNG_IMPEXP png_voidp() png_malloc_warn(png_const_structrp png_ptr, png_alloc_size_t size)
Definition: pngmem.c:213
png_set_bgr
void png_set_bgr(png_structrp png_ptr)
Definition: pngtrans.c:21
P_NOTSET
#define P_NOTSET
Definition: pngread.c:1278
png_struct_def::num_trans
png_uint_16 num_trans
Definition: pngstruct.h:247
png_gAMA
#define png_gAMA
Definition: pngpriv.h:847
png_read_finish_row
void png_read_finish_row(png_structrp png_ptr)
Definition: pngrutil.c:4313
png_gamma_significant
int png_gamma_significant(png_fixed_point gamma_val)
Definition: png.c:3515
png_do_read_intrapixel
static void png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
Definition: pngread.c:331
png_struct_def::mode
png_uint_32 mode
Definition: pngstruct.h:178
png_safe_warning
void() png_safe_warning(png_structp png_ptr, png_const_charp warning_message)
PNG_FLAG_ZSTREAM_ENDED
#define PNG_FLAG_ZSTREAM_ENDED
Definition: pngpriv.h:673
png_destroy_gamma_table
void png_destroy_gamma_table(png_structrp png_ptr)
Definition: png.c:4142
png_row_info_struct
Definition: png.h:785
png_image_read_control::image
png_imagep image
Definition: pngread.c:1303
png_pCAL
#define png_pCAL
Definition: pngpriv.h:855
png_destroy_info_struct
void png_destroy_info_struct(png_const_structrp png_ptr, png_infopp info_ptr_ptr)
Definition: png.c:386
PNG_COLOR_MASK_PALETTE
#define PNG_COLOR_MASK_PALETTE
Definition: png.h:694
PNG_INFO_sBIT
#define PNG_INFO_sBIT
Definition: png.h:764
png_read_filter_row
void png_read_filter_row(png_structrp pp, png_row_infop row_info, png_bytep row, png_const_bytep prev_row, int filter)
Definition: pngrutil.c:4118
png_handle_IHDR
void png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
Definition: pngrutil.c:838
png_tIME
#define png_tIME
Definition: pngpriv.h:863
png_image_read_control::colormap_processing
int colormap_processing
Definition: pngread.c:1314
png_set_swap
void png_set_swap(png_structrp png_ptr)
Definition: pngtrans.c:35
png_set_strip_16
PNG_IMPEXP void() png_set_strip_16(png_structrp png_ptr)
Definition: pngrtran.c:186
ip
char * ip
Definition: pngcrush.c:2189
png_fixed_point
png_int_32 png_fixed_point
Definition: pngconf.h:579
PNG_TRANSFORM_SWAP_ENDIAN
#define PNG_TRANSFORM_SWAP_ENDIAN
Definition: png.h:873
png_struct_def::interlaced
png_byte interlaced
Definition: pngstruct.h:250
length
png_uint_32 length
Definition: png.c:2253
PNG_FUNCTION
#define PNG_FUNCTION(type, name, args, attributes)
Definition: pngconf.h:293
png_handle_iCCP
void png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
Definition: pngrutil.c:1361
png_chunk_unknown_handling
int png_chunk_unknown_handling(png_const_structrp png_ptr, png_uint_32 chunk_name)
Definition: png.c:967
png_zfree
void png_zfree(voidpf png_ptr, voidpf ptr)
Definition: png.c:118
png_image_read_direct
static int png_image_read_direct(png_voidp argument)
Definition: pngread.c:3689
PNG_FP_1
#define PNG_FP_1
Definition: png.h:687
png_app_error
void png_app_error(png_const_structrp png_ptr, png_const_charp error_message)
Definition: pngerror.c:405
PNG_TRANSFORM_SHIFT
#define PNG_TRANSFORM_SHIFT
Definition: png.h:870
png_handle_IEND
void png_handle_IEND(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
Definition: pngrutil.c:1099
png_row_info_struct::bit_depth
png_byte bit_depth
Definition: png.h:790
png_set_invert_alpha
void png_set_invert_alpha(png_structrp png_ptr)
Definition: pngtrans.c:237
PNG_COLOR_TYPE_GRAY_ALPHA
#define PNG_COLOR_TYPE_GRAY_ALPHA
Definition: png.h:703
png_color_16_struct::red
png_uint_16 red
Definition: png.h:522
PNG_GAMMA_sRGB_INVERSE
#define PNG_GAMMA_sRGB_INVERSE
Definition: pngpriv.h:897
png_image_skip_unused_chunks
static void png_image_skip_unused_chunks(png_structrp png_ptr)
Definition: pngread.c:1626
PNG_CMAP_GA
#define PNG_CMAP_GA
Definition: pngread.c:1288
png_bKGD
#define png_bKGD
Definition: pngpriv.h:843
trans
png_bytep trans
Definition: pngcrush.c:2337
png_struct_def::height
png_uint_32 height
Definition: pngstruct.h:214
PNG_DIV257
#define PNG_DIV257(v16)
Definition: pngpriv.h:726
PNG_COLOR_MASK_ALPHA
#define PNG_COLOR_MASK_ALPHA
Definition: png.h:696
png_free
PNG_IMPEXP void() png_free(png_const_structrp png_ptr, png_voidp ptr)
Definition: pngmem.c:232
png_create_read_struct
png_structp png_create_read_struct(png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warn_fn)
Definition: pngread.c:37
pngcrush_timer_stop
void pngcrush_timer_stop(unsigned int n)
Definition: pngcrush.c:1605
PNG_INFO_IDAT
#define PNG_INFO_IDAT
Definition: png.h:778
png_struct_def::transformations
png_uint_32 transformations
Definition: pngstruct.h:180
png_read_png
void png_read_png(png_structrp png_ptr, png_inforp info_ptr, int transforms, voidp params)
Definition: pngread.c:1066
png_set_gray_to_rgb
PNG_IMPEXP void() png_set_gray_to_rgb(png_structrp png_ptr)
Definition: pngrtran.c:942
PNG_RGB_TO_GRAY_DEFAULT
#define PNG_RGB_TO_GRAY_DEFAULT
Definition: png.h:1110
png_set_read_fn
PNG_IMPEXP void() png_set_read_fn(png_structrp png_ptr, png_voidp io_ptr, png_rw_ptr read_data_fn)
Definition: pngrio.c:87
PNG_COLOR_TYPE_PALETTE
#define PNG_COLOR_TYPE_PALETTE
Definition: png.h:700
png_do_read_transformations
void png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
Definition: pngrtran.c:4715
PNG_SWAP_ALPHA
#define PNG_SWAP_ALPHA
Definition: pngpriv.h:650
png_create_colormap_entry
static void png_create_colormap_entry(png_image_read_control *display, png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue, png_uint_32 alpha, int encoding)
Definition: pngread.c:1779
png_sRGB
#define png_sRGB
Definition: pngpriv.h:860
PNG_CMAP_GA_BACKGROUND
#define PNG_CMAP_GA_BACKGROUND
Definition: pngread.c:1295
png_struct_def::pass
png_byte pass
Definition: pngstruct.h:251
png_do_read_interlace
void png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass, png_uint_32 transformations)
Definition: pngrutil.c:3671
png_get_channels
PNG_IMPEXP png_byte() png_get_channels(png_const_structrp png_ptr, png_const_inforp info_ptr)
Definition: pngget.c:467
png_set_packing
PNG_IMPEXP void() png_set_packing(png_structrp png_ptr)
Definition: pngtrans.c:50