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1 /* pngread.c - read a PNG file | |
2 * | |
3 * Last changed in libpng 1.6.1 [March 28, 2013] | |
4 * Copyright (c) 1998-2013 Glenn Randers-Pehrson | |
5 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) | |
6 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) | |
7 * | |
8 * This code is released under the libpng license. | |
9 * For conditions of distribution and use, see the disclaimer | |
10 * and license in png.h | |
11 * | |
12 * This file contains routines that an application calls directly to | |
13 * read a PNG file or stream. | |
14 */ | |
15 | |
16 #include "pngpriv.h" | |
17 #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) && defined(PNG_STDIO_SUPPORTED) | |
18 # include <errno.h> | |
19 #endif | |
20 | |
21 #ifdef PNG_READ_SUPPORTED | |
22 | |
23 /* Create a PNG structure for reading, and allocate any memory needed. */ | |
24 PNG_FUNCTION(png_structp,PNGAPI | |
25 png_create_read_struct,(png_const_charp user_png_ver, png_voidp error_ptr, | |
26 png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED) | |
27 { | |
28 #ifndef PNG_USER_MEM_SUPPORTED | |
29 png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr, | |
30 error_fn, warn_fn, NULL, NULL, NULL); | |
31 #else | |
32 return png_create_read_struct_2(user_png_ver, error_ptr, error_fn, | |
33 warn_fn, NULL, NULL, NULL); | |
34 } | |
35 | |
36 /* Alternate create PNG structure for reading, and allocate any memory | |
37 * needed. | |
38 */ | |
39 PNG_FUNCTION(png_structp,PNGAPI | |
40 png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr, | |
41 png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr, | |
42 png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED) | |
43 { | |
44 png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr, | |
45 error_fn, warn_fn, mem_ptr, malloc_fn, free_fn); | |
46 #endif /* PNG_USER_MEM_SUPPORTED */ | |
47 | |
48 if (png_ptr != NULL) | |
49 { | |
50 png_ptr->mode = PNG_IS_READ_STRUCT; | |
51 | |
52 /* Added in libpng-1.6.0; this can be used to detect a read structure if | |
53 * required (it will be zero in a write structure.) | |
54 */ | |
55 # ifdef PNG_SEQUENTIAL_READ_SUPPORTED | |
56 png_ptr->IDAT_read_size = PNG_IDAT_READ_SIZE; | |
57 # endif | |
58 | |
59 # ifdef PNG_BENIGN_READ_ERRORS_SUPPORTED | |
60 png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN; | |
61 | |
62 /* In stable builds only warn if an application error can be completely | |
63 * handled. | |
64 */ | |
65 # if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC | |
66 png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN; | |
67 # endif | |
68 # endif | |
69 | |
70 /* TODO: delay this, it can be done in png_init_io (if the app doesn't | |
71 * do it itself) avoiding setting the default function if it is not | |
72 * required. | |
73 */ | |
74 png_set_read_fn(png_ptr, NULL, NULL); | |
75 } | |
76 | |
77 return png_ptr; | |
78 } | |
79 | |
80 | |
81 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED | |
82 /* Read the information before the actual image data. This has been | |
83 * changed in v0.90 to allow reading a file that already has the magic | |
84 * bytes read from the stream. You can tell libpng how many bytes have | |
85 * been read from the beginning of the stream (up to the maximum of 8) | |
86 * via png_set_sig_bytes(), and we will only check the remaining bytes | |
87 * here. The application can then have access to the signature bytes we | |
88 * read if it is determined that this isn't a valid PNG file. | |
89 */ | |
90 void PNGAPI | |
91 png_read_info(png_structrp png_ptr, png_inforp info_ptr) | |
92 { | |
93 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED | |
94 int keep; | |
95 #endif | |
96 | |
97 png_debug(1, "in png_read_info"); | |
98 | |
99 if (png_ptr == NULL || info_ptr == NULL) | |
100 return; | |
101 | |
102 /* Read and check the PNG file signature. */ | |
103 png_read_sig(png_ptr, info_ptr); | |
104 | |
105 for (;;) | |
106 { | |
107 png_uint_32 length = png_read_chunk_header(png_ptr); | |
108 png_uint_32 chunk_name = png_ptr->chunk_name; | |
109 | |
110 /* IDAT logic needs to happen here to simplify getting the two flags | |
111 * right. | |
112 */ | |
113 if (chunk_name == png_IDAT) | |
114 { | |
115 if (!(png_ptr->mode & PNG_HAVE_IHDR)) | |
116 png_chunk_error(png_ptr, "Missing IHDR before IDAT"); | |
117 | |
118 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE && | |
119 !(png_ptr->mode & PNG_HAVE_PLTE)) | |
120 png_chunk_error(png_ptr, "Missing PLTE before IDAT"); | |
121 | |
122 else if (png_ptr->mode & PNG_AFTER_IDAT) | |
123 png_chunk_benign_error(png_ptr, "Too many IDATs found"); | |
124 | |
125 png_ptr->mode |= PNG_HAVE_IDAT; | |
126 } | |
127 | |
128 else if (png_ptr->mode & PNG_HAVE_IDAT) | |
129 png_ptr->mode |= PNG_AFTER_IDAT; | |
130 | |
131 /* This should be a binary subdivision search or a hash for | |
132 * matching the chunk name rather than a linear search. | |
133 */ | |
134 if (chunk_name == png_IHDR) | |
135 png_handle_IHDR(png_ptr, info_ptr, length); | |
136 | |
137 else if (chunk_name == png_IEND) | |
138 png_handle_IEND(png_ptr, info_ptr, length); | |
139 | |
140 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED | |
141 else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0) | |
142 { | |
143 png_handle_unknown(png_ptr, info_ptr, length, keep); | |
144 | |
145 if (chunk_name == png_PLTE) | |
146 png_ptr->mode |= PNG_HAVE_PLTE; | |
147 | |
148 else if (chunk_name == png_IDAT) | |
149 { | |
150 png_ptr->idat_size = 0; /* It has been consumed */ | |
151 break; | |
152 } | |
153 } | |
154 #endif | |
155 else if (chunk_name == png_PLTE) | |
156 png_handle_PLTE(png_ptr, info_ptr, length); | |
157 | |
158 else if (chunk_name == png_IDAT) | |
159 { | |
160 png_ptr->idat_size = length; | |
161 break; | |
162 } | |
163 | |
164 #ifdef PNG_READ_bKGD_SUPPORTED | |
165 else if (chunk_name == png_bKGD) | |
166 png_handle_bKGD(png_ptr, info_ptr, length); | |
167 #endif | |
168 | |
169 #ifdef PNG_READ_cHRM_SUPPORTED | |
170 else if (chunk_name == png_cHRM) | |
171 png_handle_cHRM(png_ptr, info_ptr, length); | |
172 #endif | |
173 | |
174 #ifdef PNG_READ_gAMA_SUPPORTED | |
175 else if (chunk_name == png_gAMA) | |
176 png_handle_gAMA(png_ptr, info_ptr, length); | |
177 #endif | |
178 | |
179 #ifdef PNG_READ_hIST_SUPPORTED | |
180 else if (chunk_name == png_hIST) | |
181 png_handle_hIST(png_ptr, info_ptr, length); | |
182 #endif | |
183 | |
184 #ifdef PNG_READ_oFFs_SUPPORTED | |
185 else if (chunk_name == png_oFFs) | |
186 png_handle_oFFs(png_ptr, info_ptr, length); | |
187 #endif | |
188 | |
189 #ifdef PNG_READ_pCAL_SUPPORTED | |
190 else if (chunk_name == png_pCAL) | |
191 png_handle_pCAL(png_ptr, info_ptr, length); | |
192 #endif | |
193 | |
194 #ifdef PNG_READ_sCAL_SUPPORTED | |
195 else if (chunk_name == png_sCAL) | |
196 png_handle_sCAL(png_ptr, info_ptr, length); | |
197 #endif | |
198 | |
199 #ifdef PNG_READ_pHYs_SUPPORTED | |
200 else if (chunk_name == png_pHYs) | |
201 png_handle_pHYs(png_ptr, info_ptr, length); | |
202 #endif | |
203 | |
204 #ifdef PNG_READ_sBIT_SUPPORTED | |
205 else if (chunk_name == png_sBIT) | |
206 png_handle_sBIT(png_ptr, info_ptr, length); | |
207 #endif | |
208 | |
209 #ifdef PNG_READ_sRGB_SUPPORTED | |
210 else if (chunk_name == png_sRGB) | |
211 png_handle_sRGB(png_ptr, info_ptr, length); | |
212 #endif | |
213 | |
214 #ifdef PNG_READ_iCCP_SUPPORTED | |
215 else if (chunk_name == png_iCCP) | |
216 png_handle_iCCP(png_ptr, info_ptr, length); | |
217 #endif | |
218 | |
219 #ifdef PNG_READ_sPLT_SUPPORTED | |
220 else if (chunk_name == png_sPLT) | |
221 png_handle_sPLT(png_ptr, info_ptr, length); | |
222 #endif | |
223 | |
224 #ifdef PNG_READ_tEXt_SUPPORTED | |
225 else if (chunk_name == png_tEXt) | |
226 png_handle_tEXt(png_ptr, info_ptr, length); | |
227 #endif | |
228 | |
229 #ifdef PNG_READ_tIME_SUPPORTED | |
230 else if (chunk_name == png_tIME) | |
231 png_handle_tIME(png_ptr, info_ptr, length); | |
232 #endif | |
233 | |
234 #ifdef PNG_READ_tRNS_SUPPORTED | |
235 else if (chunk_name == png_tRNS) | |
236 png_handle_tRNS(png_ptr, info_ptr, length); | |
237 #endif | |
238 | |
239 #ifdef PNG_READ_zTXt_SUPPORTED | |
240 else if (chunk_name == png_zTXt) | |
241 png_handle_zTXt(png_ptr, info_ptr, length); | |
242 #endif | |
243 | |
244 #ifdef PNG_READ_iTXt_SUPPORTED | |
245 else if (chunk_name == png_iTXt) | |
246 png_handle_iTXt(png_ptr, info_ptr, length); | |
247 #endif | |
248 | |
249 else | |
250 png_handle_unknown(png_ptr, info_ptr, length, | |
251 PNG_HANDLE_CHUNK_AS_DEFAULT); | |
252 } | |
253 } | |
254 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ | |
255 | |
256 /* Optional call to update the users info_ptr structure */ | |
257 void PNGAPI | |
258 png_read_update_info(png_structrp png_ptr, png_inforp info_ptr) | |
259 { | |
260 png_debug(1, "in png_read_update_info"); | |
261 | |
262 if (png_ptr != NULL) | |
263 { | |
264 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) | |
265 { | |
266 png_read_start_row(png_ptr); | |
267 | |
268 # ifdef PNG_READ_TRANSFORMS_SUPPORTED | |
269 png_read_transform_info(png_ptr, info_ptr); | |
270 # else | |
271 PNG_UNUSED(info_ptr) | |
272 # endif | |
273 } | |
274 | |
275 /* New in 1.6.0 this avoids the bug of doing the initializations twice */ | |
276 else | |
277 png_app_error(png_ptr, | |
278 "png_read_update_info/png_start_read_image: duplicate call"); | |
279 } | |
280 } | |
281 | |
282 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED | |
283 /* Initialize palette, background, etc, after transformations | |
284 * are set, but before any reading takes place. This allows | |
285 * the user to obtain a gamma-corrected palette, for example. | |
286 * If the user doesn't call this, we will do it ourselves. | |
287 */ | |
288 void PNGAPI | |
289 png_start_read_image(png_structrp png_ptr) | |
290 { | |
291 png_debug(1, "in png_start_read_image"); | |
292 | |
293 if (png_ptr != NULL) | |
294 { | |
295 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) | |
296 png_read_start_row(png_ptr); | |
297 | |
298 /* New in 1.6.0 this avoids the bug of doing the initializations twice */ | |
299 else | |
300 png_app_error(png_ptr, | |
301 "png_start_read_image/png_read_update_info: duplicate call"); | |
302 } | |
303 } | |
304 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ | |
305 | |
306 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED | |
307 void PNGAPI | |
308 png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row) | |
309 { | |
310 png_row_info row_info; | |
311 | |
312 if (png_ptr == NULL) | |
313 return; | |
314 | |
315 png_debug2(1, "in png_read_row (row %lu, pass %d)", | |
316 (unsigned long)png_ptr->row_number, png_ptr->pass); | |
317 | |
318 /* png_read_start_row sets the information (in particular iwidth) for this | |
319 * interlace pass. | |
320 */ | |
321 if (!(png_ptr->flags & PNG_FLAG_ROW_INIT)) | |
322 png_read_start_row(png_ptr); | |
323 | |
324 /* 1.5.6: row_info moved out of png_struct to a local here. */ | |
325 row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */ | |
326 row_info.color_type = png_ptr->color_type; | |
327 row_info.bit_depth = png_ptr->bit_depth; | |
328 row_info.channels = png_ptr->channels; | |
329 row_info.pixel_depth = png_ptr->pixel_depth; | |
330 row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width); | |
331 | |
332 if (png_ptr->row_number == 0 && png_ptr->pass == 0) | |
333 { | |
334 /* Check for transforms that have been set but were defined out */ | |
335 #if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED) | |
336 if (png_ptr->transformations & PNG_INVERT_MONO) | |
337 png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined"); | |
338 #endif | |
339 | |
340 #if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED) | |
341 if (png_ptr->transformations & PNG_FILLER) | |
342 png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined"); | |
343 #endif | |
344 | |
345 #if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \ | |
346 !defined(PNG_READ_PACKSWAP_SUPPORTED) | |
347 if (png_ptr->transformations & PNG_PACKSWAP) | |
348 png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined"); | |
349 #endif | |
350 | |
351 #if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED) | |
352 if (png_ptr->transformations & PNG_PACK) | |
353 png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined"); | |
354 #endif | |
355 | |
356 #if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED) | |
357 if (png_ptr->transformations & PNG_SHIFT) | |
358 png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined"); | |
359 #endif | |
360 | |
361 #if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED) | |
362 if (png_ptr->transformations & PNG_BGR) | |
363 png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined"); | |
364 #endif | |
365 | |
366 #if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED) | |
367 if (png_ptr->transformations & PNG_SWAP_BYTES) | |
368 png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined"); | |
369 #endif | |
370 } | |
371 | |
372 #ifdef PNG_READ_INTERLACING_SUPPORTED | |
373 /* If interlaced and we do not need a new row, combine row and return. | |
374 * Notice that the pixels we have from previous rows have been transformed | |
375 * already; we can only combine like with like (transformed or | |
376 * untransformed) and, because of the libpng API for interlaced images, this | |
377 * means we must transform before de-interlacing. | |
378 */ | |
379 if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE)) | |
380 { | |
381 switch (png_ptr->pass) | |
382 { | |
383 case 0: | |
384 if (png_ptr->row_number & 0x07) | |
385 { | |
386 if (dsp_row != NULL) | |
387 png_combine_row(png_ptr, dsp_row, 1/*display*/); | |
388 png_read_finish_row(png_ptr); | |
389 return; | |
390 } | |
391 break; | |
392 | |
393 case 1: | |
394 if ((png_ptr->row_number & 0x07) || png_ptr->width < 5) | |
395 { | |
396 if (dsp_row != NULL) | |
397 png_combine_row(png_ptr, dsp_row, 1/*display*/); | |
398 | |
399 png_read_finish_row(png_ptr); | |
400 return; | |
401 } | |
402 break; | |
403 | |
404 case 2: | |
405 if ((png_ptr->row_number & 0x07) != 4) | |
406 { | |
407 if (dsp_row != NULL && (png_ptr->row_number & 4)) | |
408 png_combine_row(png_ptr, dsp_row, 1/*display*/); | |
409 | |
410 png_read_finish_row(png_ptr); | |
411 return; | |
412 } | |
413 break; | |
414 | |
415 case 3: | |
416 if ((png_ptr->row_number & 3) || png_ptr->width < 3) | |
417 { | |
418 if (dsp_row != NULL) | |
419 png_combine_row(png_ptr, dsp_row, 1/*display*/); | |
420 | |
421 png_read_finish_row(png_ptr); | |
422 return; | |
423 } | |
424 break; | |
425 | |
426 case 4: | |
427 if ((png_ptr->row_number & 3) != 2) | |
428 { | |
429 if (dsp_row != NULL && (png_ptr->row_number & 2)) | |
430 png_combine_row(png_ptr, dsp_row, 1/*display*/); | |
431 | |
432 png_read_finish_row(png_ptr); | |
433 return; | |
434 } | |
435 break; | |
436 | |
437 case 5: | |
438 if ((png_ptr->row_number & 1) || png_ptr->width < 2) | |
439 { | |
440 if (dsp_row != NULL) | |
441 png_combine_row(png_ptr, dsp_row, 1/*display*/); | |
442 | |
443 png_read_finish_row(png_ptr); | |
444 return; | |
445 } | |
446 break; | |
447 | |
448 default: | |
449 case 6: | |
450 if (!(png_ptr->row_number & 1)) | |
451 { | |
452 png_read_finish_row(png_ptr); | |
453 return; | |
454 } | |
455 break; | |
456 } | |
457 } | |
458 #endif | |
459 | |
460 if (!(png_ptr->mode & PNG_HAVE_IDAT)) | |
461 png_error(png_ptr, "Invalid attempt to read row data"); | |
462 | |
463 /* Fill the row with IDAT data: */ | |
464 png_read_IDAT_data(png_ptr, png_ptr->row_buf, row_info.rowbytes + 1); | |
465 | |
466 if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE) | |
467 { | |
468 if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST) | |
469 png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1, | |
470 png_ptr->prev_row + 1, png_ptr->row_buf[0]); | |
471 else | |
472 png_error(png_ptr, "bad adaptive filter value"); | |
473 } | |
474 | |
475 /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before | |
476 * 1.5.6, while the buffer really is this big in current versions of libpng | |
477 * it may not be in the future, so this was changed just to copy the | |
478 * interlaced count: | |
479 */ | |
480 memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1); | |
481 | |
482 #ifdef PNG_MNG_FEATURES_SUPPORTED | |
483 if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) && | |
484 (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING)) | |
485 { | |
486 /* Intrapixel differencing */ | |
487 png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1); | |
488 } | |
489 #endif | |
490 | |
491 | |
492 #ifdef PNG_READ_TRANSFORMS_SUPPORTED | |
493 if (png_ptr->transformations) | |
494 png_do_read_transformations(png_ptr, &row_info); | |
495 #endif | |
496 | |
497 /* The transformed pixel depth should match the depth now in row_info. */ | |
498 if (png_ptr->transformed_pixel_depth == 0) | |
499 { | |
500 png_ptr->transformed_pixel_depth = row_info.pixel_depth; | |
501 if (row_info.pixel_depth > png_ptr->maximum_pixel_depth) | |
502 png_error(png_ptr, "sequential row overflow"); | |
503 } | |
504 | |
505 else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth) | |
506 png_error(png_ptr, "internal sequential row size calculation error"); | |
507 | |
508 #ifdef PNG_READ_INTERLACING_SUPPORTED | |
509 /* Blow up interlaced rows to full size */ | |
510 if (png_ptr->interlaced && | |
511 (png_ptr->transformations & PNG_INTERLACE)) | |
512 { | |
513 if (png_ptr->pass < 6) | |
514 png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass, | |
515 png_ptr->transformations); | |
516 | |
517 if (dsp_row != NULL) | |
518 png_combine_row(png_ptr, dsp_row, 1/*display*/); | |
519 | |
520 if (row != NULL) | |
521 png_combine_row(png_ptr, row, 0/*row*/); | |
522 } | |
523 | |
524 else | |
525 #endif | |
526 { | |
527 if (row != NULL) | |
528 png_combine_row(png_ptr, row, -1/*ignored*/); | |
529 | |
530 if (dsp_row != NULL) | |
531 png_combine_row(png_ptr, dsp_row, -1/*ignored*/); | |
532 } | |
533 png_read_finish_row(png_ptr); | |
534 | |
535 if (png_ptr->read_row_fn != NULL) | |
536 (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass); | |
537 | |
538 } | |
539 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ | |
540 | |
541 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED | |
542 /* Read one or more rows of image data. If the image is interlaced, | |
543 * and png_set_interlace_handling() has been called, the rows need to | |
544 * contain the contents of the rows from the previous pass. If the | |
545 * image has alpha or transparency, and png_handle_alpha()[*] has been | |
546 * called, the rows contents must be initialized to the contents of the | |
547 * screen. | |
548 * | |
549 * "row" holds the actual image, and pixels are placed in it | |
550 * as they arrive. If the image is displayed after each pass, it will | |
551 * appear to "sparkle" in. "display_row" can be used to display a | |
552 * "chunky" progressive image, with finer detail added as it becomes | |
553 * available. If you do not want this "chunky" display, you may pass | |
554 * NULL for display_row. If you do not want the sparkle display, and | |
555 * you have not called png_handle_alpha(), you may pass NULL for rows. | |
556 * If you have called png_handle_alpha(), and the image has either an | |
557 * alpha channel or a transparency chunk, you must provide a buffer for | |
558 * rows. In this case, you do not have to provide a display_row buffer | |
559 * also, but you may. If the image is not interlaced, or if you have | |
560 * not called png_set_interlace_handling(), the display_row buffer will | |
561 * be ignored, so pass NULL to it. | |
562 * | |
563 * [*] png_handle_alpha() does not exist yet, as of this version of libpng | |
564 */ | |
565 | |
566 void PNGAPI | |
567 png_read_rows(png_structrp png_ptr, png_bytepp row, | |
568 png_bytepp display_row, png_uint_32 num_rows) | |
569 { | |
570 png_uint_32 i; | |
571 png_bytepp rp; | |
572 png_bytepp dp; | |
573 | |
574 png_debug(1, "in png_read_rows"); | |
575 | |
576 if (png_ptr == NULL) | |
577 return; | |
578 | |
579 rp = row; | |
580 dp = display_row; | |
581 if (rp != NULL && dp != NULL) | |
582 for (i = 0; i < num_rows; i++) | |
583 { | |
584 png_bytep rptr = *rp++; | |
585 png_bytep dptr = *dp++; | |
586 | |
587 png_read_row(png_ptr, rptr, dptr); | |
588 } | |
589 | |
590 else if (rp != NULL) | |
591 for (i = 0; i < num_rows; i++) | |
592 { | |
593 png_bytep rptr = *rp; | |
594 png_read_row(png_ptr, rptr, NULL); | |
595 rp++; | |
596 } | |
597 | |
598 else if (dp != NULL) | |
599 for (i = 0; i < num_rows; i++) | |
600 { | |
601 png_bytep dptr = *dp; | |
602 png_read_row(png_ptr, NULL, dptr); | |
603 dp++; | |
604 } | |
605 } | |
606 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ | |
607 | |
608 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED | |
609 /* Read the entire image. If the image has an alpha channel or a tRNS | |
610 * chunk, and you have called png_handle_alpha()[*], you will need to | |
611 * initialize the image to the current image that PNG will be overlaying. | |
612 * We set the num_rows again here, in case it was incorrectly set in | |
613 * png_read_start_row() by a call to png_read_update_info() or | |
614 * png_start_read_image() if png_set_interlace_handling() wasn't called | |
615 * prior to either of these functions like it should have been. You can | |
616 * only call this function once. If you desire to have an image for | |
617 * each pass of a interlaced image, use png_read_rows() instead. | |
618 * | |
619 * [*] png_handle_alpha() does not exist yet, as of this version of libpng | |
620 */ | |
621 void PNGAPI | |
622 png_read_image(png_structrp png_ptr, png_bytepp image) | |
623 { | |
624 png_uint_32 i, image_height; | |
625 int pass, j; | |
626 png_bytepp rp; | |
627 | |
628 png_debug(1, "in png_read_image"); | |
629 | |
630 if (png_ptr == NULL) | |
631 return; | |
632 | |
633 #ifdef PNG_READ_INTERLACING_SUPPORTED | |
634 if (!(png_ptr->flags & PNG_FLAG_ROW_INIT)) | |
635 { | |
636 pass = png_set_interlace_handling(png_ptr); | |
637 /* And make sure transforms are initialized. */ | |
638 png_start_read_image(png_ptr); | |
639 } | |
640 else | |
641 { | |
642 if (png_ptr->interlaced && !(png_ptr->transformations & PNG_INTERLACE)) | |
643 { | |
644 /* Caller called png_start_read_image or png_read_update_info without | |
645 * first turning on the PNG_INTERLACE transform. We can fix this here, | |
646 * but the caller should do it! | |
647 */ | |
648 png_warning(png_ptr, "Interlace handling should be turned on when " | |
649 "using png_read_image"); | |
650 /* Make sure this is set correctly */ | |
651 png_ptr->num_rows = png_ptr->height; | |
652 } | |
653 | |
654 /* Obtain the pass number, which also turns on the PNG_INTERLACE flag in | |
655 * the above error case. | |
656 */ | |
657 pass = png_set_interlace_handling(png_ptr); | |
658 } | |
659 #else | |
660 if (png_ptr->interlaced) | |
661 png_error(png_ptr, | |
662 "Cannot read interlaced image -- interlace handler disabled"); | |
663 | |
664 pass = 1; | |
665 #endif | |
666 | |
667 image_height=png_ptr->height; | |
668 | |
669 for (j = 0; j < pass; j++) | |
670 { | |
671 rp = image; | |
672 for (i = 0; i < image_height; i++) | |
673 { | |
674 png_read_row(png_ptr, *rp, NULL); | |
675 rp++; | |
676 } | |
677 } | |
678 } | |
679 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ | |
680 | |
681 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED | |
682 /* Read the end of the PNG file. Will not read past the end of the | |
683 * file, will verify the end is accurate, and will read any comments | |
684 * or time information at the end of the file, if info is not NULL. | |
685 */ | |
686 void PNGAPI | |
687 png_read_end(png_structrp png_ptr, png_inforp info_ptr) | |
688 { | |
689 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED | |
690 int keep; | |
691 #endif | |
692 | |
693 png_debug(1, "in png_read_end"); | |
694 | |
695 if (png_ptr == NULL) | |
696 return; | |
697 | |
698 /* If png_read_end is called in the middle of reading the rows there may | |
699 * still be pending IDAT data and an owned zstream. Deal with this here. | |
700 */ | |
701 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED | |
702 if (!png_chunk_unknown_handling(png_ptr, png_IDAT)) | |
703 #endif | |
704 png_read_finish_IDAT(png_ptr); | |
705 | |
706 #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED | |
707 /* Report invalid palette index; added at libng-1.5.10 */ | |
708 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE && | |
709 png_ptr->num_palette_max > png_ptr->num_palette) | |
710 png_benign_error(png_ptr, "Read palette index exceeding num_palette"); | |
711 #endif | |
712 | |
713 do | |
714 { | |
715 png_uint_32 length = png_read_chunk_header(png_ptr); | |
716 png_uint_32 chunk_name = png_ptr->chunk_name; | |
717 | |
718 if (chunk_name == png_IHDR) | |
719 png_handle_IHDR(png_ptr, info_ptr, length); | |
720 | |
721 else if (chunk_name == png_IEND) | |
722 png_handle_IEND(png_ptr, info_ptr, length); | |
723 | |
724 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED | |
725 else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0) | |
726 { | |
727 if (chunk_name == png_IDAT) | |
728 { | |
729 if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT)) | |
730 png_benign_error(png_ptr, "Too many IDATs found"); | |
731 } | |
732 png_handle_unknown(png_ptr, info_ptr, length, keep); | |
733 if (chunk_name == png_PLTE) | |
734 png_ptr->mode |= PNG_HAVE_PLTE; | |
735 } | |
736 #endif | |
737 | |
738 else if (chunk_name == png_IDAT) | |
739 { | |
740 /* Zero length IDATs are legal after the last IDAT has been | |
741 * read, but not after other chunks have been read. | |
742 */ | |
743 if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT)) | |
744 png_benign_error(png_ptr, "Too many IDATs found"); | |
745 | |
746 png_crc_finish(png_ptr, length); | |
747 } | |
748 else if (chunk_name == png_PLTE) | |
749 png_handle_PLTE(png_ptr, info_ptr, length); | |
750 | |
751 #ifdef PNG_READ_bKGD_SUPPORTED | |
752 else if (chunk_name == png_bKGD) | |
753 png_handle_bKGD(png_ptr, info_ptr, length); | |
754 #endif | |
755 | |
756 #ifdef PNG_READ_cHRM_SUPPORTED | |
757 else if (chunk_name == png_cHRM) | |
758 png_handle_cHRM(png_ptr, info_ptr, length); | |
759 #endif | |
760 | |
761 #ifdef PNG_READ_gAMA_SUPPORTED | |
762 else if (chunk_name == png_gAMA) | |
763 png_handle_gAMA(png_ptr, info_ptr, length); | |
764 #endif | |
765 | |
766 #ifdef PNG_READ_hIST_SUPPORTED | |
767 else if (chunk_name == png_hIST) | |
768 png_handle_hIST(png_ptr, info_ptr, length); | |
769 #endif | |
770 | |
771 #ifdef PNG_READ_oFFs_SUPPORTED | |
772 else if (chunk_name == png_oFFs) | |
773 png_handle_oFFs(png_ptr, info_ptr, length); | |
774 #endif | |
775 | |
776 #ifdef PNG_READ_pCAL_SUPPORTED | |
777 else if (chunk_name == png_pCAL) | |
778 png_handle_pCAL(png_ptr, info_ptr, length); | |
779 #endif | |
780 | |
781 #ifdef PNG_READ_sCAL_SUPPORTED | |
782 else if (chunk_name == png_sCAL) | |
783 png_handle_sCAL(png_ptr, info_ptr, length); | |
784 #endif | |
785 | |
786 #ifdef PNG_READ_pHYs_SUPPORTED | |
787 else if (chunk_name == png_pHYs) | |
788 png_handle_pHYs(png_ptr, info_ptr, length); | |
789 #endif | |
790 | |
791 #ifdef PNG_READ_sBIT_SUPPORTED | |
792 else if (chunk_name == png_sBIT) | |
793 png_handle_sBIT(png_ptr, info_ptr, length); | |
794 #endif | |
795 | |
796 #ifdef PNG_READ_sRGB_SUPPORTED | |
797 else if (chunk_name == png_sRGB) | |
798 png_handle_sRGB(png_ptr, info_ptr, length); | |
799 #endif | |
800 | |
801 #ifdef PNG_READ_iCCP_SUPPORTED | |
802 else if (chunk_name == png_iCCP) | |
803 png_handle_iCCP(png_ptr, info_ptr, length); | |
804 #endif | |
805 | |
806 #ifdef PNG_READ_sPLT_SUPPORTED | |
807 else if (chunk_name == png_sPLT) | |
808 png_handle_sPLT(png_ptr, info_ptr, length); | |
809 #endif | |
810 | |
811 #ifdef PNG_READ_tEXt_SUPPORTED | |
812 else if (chunk_name == png_tEXt) | |
813 png_handle_tEXt(png_ptr, info_ptr, length); | |
814 #endif | |
815 | |
816 #ifdef PNG_READ_tIME_SUPPORTED | |
817 else if (chunk_name == png_tIME) | |
818 png_handle_tIME(png_ptr, info_ptr, length); | |
819 #endif | |
820 | |
821 #ifdef PNG_READ_tRNS_SUPPORTED | |
822 else if (chunk_name == png_tRNS) | |
823 png_handle_tRNS(png_ptr, info_ptr, length); | |
824 #endif | |
825 | |
826 #ifdef PNG_READ_zTXt_SUPPORTED | |
827 else if (chunk_name == png_zTXt) | |
828 png_handle_zTXt(png_ptr, info_ptr, length); | |
829 #endif | |
830 | |
831 #ifdef PNG_READ_iTXt_SUPPORTED | |
832 else if (chunk_name == png_iTXt) | |
833 png_handle_iTXt(png_ptr, info_ptr, length); | |
834 #endif | |
835 | |
836 else | |
837 png_handle_unknown(png_ptr, info_ptr, length, | |
838 PNG_HANDLE_CHUNK_AS_DEFAULT); | |
839 } while (!(png_ptr->mode & PNG_HAVE_IEND)); | |
840 } | |
841 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ | |
842 | |
843 /* Free all memory used in the read struct */ | |
844 static void | |
845 png_read_destroy(png_structrp png_ptr) | |
846 { | |
847 png_debug(1, "in png_read_destroy"); | |
848 | |
849 #ifdef PNG_READ_GAMMA_SUPPORTED | |
850 png_destroy_gamma_table(png_ptr); | |
851 #endif | |
852 | |
853 png_free(png_ptr, png_ptr->big_row_buf); | |
854 png_free(png_ptr, png_ptr->big_prev_row); | |
855 png_free(png_ptr, png_ptr->read_buffer); | |
856 | |
857 #ifdef PNG_READ_QUANTIZE_SUPPORTED | |
858 png_free(png_ptr, png_ptr->palette_lookup); | |
859 png_free(png_ptr, png_ptr->quantize_index); | |
860 #endif | |
861 | |
862 if (png_ptr->free_me & PNG_FREE_PLTE) | |
863 png_zfree(png_ptr, png_ptr->palette); | |
864 png_ptr->free_me &= ~PNG_FREE_PLTE; | |
865 | |
866 #if defined(PNG_tRNS_SUPPORTED) || \ | |
867 defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) | |
868 if (png_ptr->free_me & PNG_FREE_TRNS) | |
869 png_free(png_ptr, png_ptr->trans_alpha); | |
870 png_ptr->free_me &= ~PNG_FREE_TRNS; | |
871 #endif | |
872 | |
873 inflateEnd(&png_ptr->zstream); | |
874 | |
875 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED | |
876 png_free(png_ptr, png_ptr->save_buffer); | |
877 #endif | |
878 | |
879 #if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) &&\ | |
880 defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) | |
881 png_free(png_ptr, png_ptr->unknown_chunk.data); | |
882 #endif | |
883 | |
884 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED | |
885 png_free(png_ptr, png_ptr->chunk_list); | |
886 #endif | |
887 | |
888 /* NOTE: the 'setjmp' buffer may still be allocated and the memory and error | |
889 * callbacks are still set at this point. They are required to complete the | |
890 * destruction of the png_struct itself. | |
891 */ | |
892 } | |
893 | |
894 /* Free all memory used by the read */ | |
895 void PNGAPI | |
896 png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr, | |
897 png_infopp end_info_ptr_ptr) | |
898 { | |
899 png_structrp png_ptr = NULL; | |
900 | |
901 png_debug(1, "in png_destroy_read_struct"); | |
902 | |
903 if (png_ptr_ptr != NULL) | |
904 png_ptr = *png_ptr_ptr; | |
905 | |
906 if (png_ptr == NULL) | |
907 return; | |
908 | |
909 /* libpng 1.6.0: use the API to destroy info structs to ensure consistent | |
910 * behavior. Prior to 1.6.0 libpng did extra 'info' destruction in this API. | |
911 * The extra was, apparently, unnecessary yet this hides memory leak bugs. | |
912 */ | |
913 png_destroy_info_struct(png_ptr, end_info_ptr_ptr); | |
914 png_destroy_info_struct(png_ptr, info_ptr_ptr); | |
915 | |
916 *png_ptr_ptr = NULL; | |
917 png_read_destroy(png_ptr); | |
918 png_destroy_png_struct(png_ptr); | |
919 } | |
920 | |
921 void PNGAPI | |
922 png_set_read_status_fn(png_structrp png_ptr, png_read_status_ptr read_row_fn) | |
923 { | |
924 if (png_ptr == NULL) | |
925 return; | |
926 | |
927 png_ptr->read_row_fn = read_row_fn; | |
928 } | |
929 | |
930 | |
931 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED | |
932 #ifdef PNG_INFO_IMAGE_SUPPORTED | |
933 void PNGAPI | |
934 png_read_png(png_structrp png_ptr, png_inforp info_ptr, | |
935 int transforms, | |
936 voidp params) | |
937 { | |
938 int row; | |
939 | |
940 if (png_ptr == NULL || info_ptr == NULL) | |
941 return; | |
942 | |
943 /* png_read_info() gives us all of the information from the | |
944 * PNG file before the first IDAT (image data chunk). | |
945 */ | |
946 png_read_info(png_ptr, info_ptr); | |
947 if (info_ptr->height > PNG_UINT_32_MAX/(sizeof (png_bytep))) | |
948 png_error(png_ptr, "Image is too high to process with png_read_png()"); | |
949 | |
950 /* -------------- image transformations start here ------------------- */ | |
951 | |
952 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED | |
953 /* Tell libpng to strip 16-bit/color files down to 8 bits per color. | |
954 */ | |
955 if (transforms & PNG_TRANSFORM_SCALE_16) | |
956 { | |
957 /* Added at libpng-1.5.4. "strip_16" produces the same result that it | |
958 * did in earlier versions, while "scale_16" is now more accurate. | |
959 */ | |
960 png_set_scale_16(png_ptr); | |
961 } | |
962 #endif | |
963 | |
964 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED | |
965 /* If both SCALE and STRIP are required pngrtran will effectively cancel the | |
966 * latter by doing SCALE first. This is ok and allows apps not to check for | |
967 * which is supported to get the right answer. | |
968 */ | |
969 if (transforms & PNG_TRANSFORM_STRIP_16) | |
970 png_set_strip_16(png_ptr); | |
971 #endif | |
972 | |
973 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED | |
974 /* Strip alpha bytes from the input data without combining with | |
975 * the background (not recommended). | |
976 */ | |
977 if (transforms & PNG_TRANSFORM_STRIP_ALPHA) | |
978 png_set_strip_alpha(png_ptr); | |
979 #endif | |
980 | |
981 #if defined(PNG_READ_PACK_SUPPORTED) && !defined(PNG_READ_EXPAND_SUPPORTED) | |
982 /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single | |
983 * byte into separate bytes (useful for paletted and grayscale images). | |
984 */ | |
985 if (transforms & PNG_TRANSFORM_PACKING) | |
986 png_set_packing(png_ptr); | |
987 #endif | |
988 | |
989 #ifdef PNG_READ_PACKSWAP_SUPPORTED | |
990 /* Change the order of packed pixels to least significant bit first | |
991 * (not useful if you are using png_set_packing). | |
992 */ | |
993 if (transforms & PNG_TRANSFORM_PACKSWAP) | |
994 png_set_packswap(png_ptr); | |
995 #endif | |
996 | |
997 #ifdef PNG_READ_EXPAND_SUPPORTED | |
998 /* Expand paletted colors into true RGB triplets | |
999 * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel | |
1000 * Expand paletted or RGB images with transparency to full alpha | |
1001 * channels so the data will be available as RGBA quartets. | |
1002 */ | |
1003 if (transforms & PNG_TRANSFORM_EXPAND) | |
1004 if ((png_ptr->bit_depth < 8) || | |
1005 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) || | |
1006 (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))) | |
1007 png_set_expand(png_ptr); | |
1008 #endif | |
1009 | |
1010 /* We don't handle background color or gamma transformation or quantizing. | |
1011 */ | |
1012 | |
1013 #ifdef PNG_READ_INVERT_SUPPORTED | |
1014 /* Invert monochrome files to have 0 as white and 1 as black | |
1015 */ | |
1016 if (transforms & PNG_TRANSFORM_INVERT_MONO) | |
1017 png_set_invert_mono(png_ptr); | |
1018 #endif | |
1019 | |
1020 #ifdef PNG_READ_SHIFT_SUPPORTED | |
1021 /* If you want to shift the pixel values from the range [0,255] or | |
1022 * [0,65535] to the original [0,7] or [0,31], or whatever range the | |
1023 * colors were originally in: | |
1024 */ | |
1025 if ((transforms & PNG_TRANSFORM_SHIFT) | |
1026 && png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT)) | |
1027 { | |
1028 png_color_8p sig_bit; | |
1029 | |
1030 png_get_sBIT(png_ptr, info_ptr, &sig_bit); | |
1031 png_set_shift(png_ptr, sig_bit); | |
1032 } | |
1033 #endif | |
1034 | |
1035 #ifdef PNG_READ_BGR_SUPPORTED | |
1036 /* Flip the RGB pixels to BGR (or RGBA to BGRA) */ | |
1037 if (transforms & PNG_TRANSFORM_BGR) | |
1038 png_set_bgr(png_ptr); | |
1039 #endif | |
1040 | |
1041 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED | |
1042 /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */ | |
1043 if (transforms & PNG_TRANSFORM_SWAP_ALPHA) | |
1044 png_set_swap_alpha(png_ptr); | |
1045 #endif | |
1046 | |
1047 #ifdef PNG_READ_SWAP_SUPPORTED | |
1048 /* Swap bytes of 16-bit files to least significant byte first */ | |
1049 if (transforms & PNG_TRANSFORM_SWAP_ENDIAN) | |
1050 png_set_swap(png_ptr); | |
1051 #endif | |
1052 | |
1053 /* Added at libpng-1.2.41 */ | |
1054 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED | |
1055 /* Invert the alpha channel from opacity to transparency */ | |
1056 if (transforms & PNG_TRANSFORM_INVERT_ALPHA) | |
1057 png_set_invert_alpha(png_ptr); | |
1058 #endif | |
1059 | |
1060 /* Added at libpng-1.2.41 */ | |
1061 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED | |
1062 /* Expand grayscale image to RGB */ | |
1063 if (transforms & PNG_TRANSFORM_GRAY_TO_RGB) | |
1064 png_set_gray_to_rgb(png_ptr); | |
1065 #endif | |
1066 | |
1067 /* Added at libpng-1.5.4 */ | |
1068 #ifdef PNG_READ_EXPAND_16_SUPPORTED | |
1069 if (transforms & PNG_TRANSFORM_EXPAND_16) | |
1070 png_set_expand_16(png_ptr); | |
1071 #endif | |
1072 | |
1073 /* We don't handle adding filler bytes */ | |
1074 | |
1075 /* We use png_read_image and rely on that for interlace handling, but we also | |
1076 * call png_read_update_info therefore must turn on interlace handling now: | |
1077 */ | |
1078 (void)png_set_interlace_handling(png_ptr); | |
1079 | |
1080 /* Optional call to gamma correct and add the background to the palette | |
1081 * and update info structure. REQUIRED if you are expecting libpng to | |
1082 * update the palette for you (i.e., you selected such a transform above). | |
1083 */ | |
1084 png_read_update_info(png_ptr, info_ptr); | |
1085 | |
1086 /* -------------- image transformations end here ------------------- */ | |
1087 | |
1088 png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0); | |
1089 if (info_ptr->row_pointers == NULL) | |
1090 { | |
1091 png_uint_32 iptr; | |
1092 | |
1093 info_ptr->row_pointers = (png_bytepp)png_malloc(png_ptr, | |
1094 info_ptr->height * (sizeof (png_bytep))); | |
1095 for (iptr=0; iptr<info_ptr->height; iptr++) | |
1096 info_ptr->row_pointers[iptr] = NULL; | |
1097 | |
1098 info_ptr->free_me |= PNG_FREE_ROWS; | |
1099 | |
1100 for (row = 0; row < (int)info_ptr->height; row++) | |
1101 info_ptr->row_pointers[row] = (png_bytep)png_malloc(png_ptr, | |
1102 png_get_rowbytes(png_ptr, info_ptr)); | |
1103 } | |
1104 | |
1105 png_read_image(png_ptr, info_ptr->row_pointers); | |
1106 info_ptr->valid |= PNG_INFO_IDAT; | |
1107 | |
1108 /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */ | |
1109 png_read_end(png_ptr, info_ptr); | |
1110 | |
1111 PNG_UNUSED(transforms) /* Quiet compiler warnings */ | |
1112 PNG_UNUSED(params) | |
1113 | |
1114 } | |
1115 #endif /* PNG_INFO_IMAGE_SUPPORTED */ | |
1116 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ | |
1117 | |
1118 #ifdef PNG_SIMPLIFIED_READ_SUPPORTED | |
1119 /* SIMPLIFIED READ | |
1120 * | |
1121 * This code currently relies on the sequential reader, though it could easily | |
1122 * be made to work with the progressive one. | |
1123 */ | |
1124 /* Arguments to png_image_finish_read: */ | |
1125 | |
1126 /* Encoding of PNG data (used by the color-map code) */ | |
1127 /* TODO: change these, dang, ANSI-C reserves the 'E' namespace. */ | |
1128 # define E_NOTSET 0 /* File encoding not yet known */ | |
1129 # define E_sRGB 1 /* 8-bit encoded to sRGB gamma */ | |
1130 # define E_LINEAR 2 /* 16-bit linear: not encoded, NOT pre-multiplied! */ | |
1131 # define E_FILE 3 /* 8-bit encoded to file gamma, not sRGB or linear */ | |
1132 # define E_LINEAR8 4 /* 8-bit linear: only from a file value */ | |
1133 | |
1134 /* Color-map processing: after libpng has run on the PNG image further | |
1135 * processing may be needed to conver the data to color-map indicies. | |
1136 */ | |
1137 #define PNG_CMAP_NONE 0 | |
1138 #define PNG_CMAP_GA 1 /* Process GA data to a color-map with alpha */ | |
1139 #define PNG_CMAP_TRANS 2 /* Process GA data to a background index */ | |
1140 #define PNG_CMAP_RGB 3 /* Process RGB data */ | |
1141 #define PNG_CMAP_RGB_ALPHA 4 /* Process RGBA data */ | |
1142 | |
1143 /* The following document where the background is for each processing case. */ | |
1144 #define PNG_CMAP_NONE_BACKGROUND 256 | |
1145 #define PNG_CMAP_GA_BACKGROUND 231 | |
1146 #define PNG_CMAP_TRANS_BACKGROUND 254 | |
1147 #define PNG_CMAP_RGB_BACKGROUND 256 | |
1148 #define PNG_CMAP_RGB_ALPHA_BACKGROUND 216 | |
1149 | |
1150 typedef struct | |
1151 { | |
1152 /* Arguments: */ | |
1153 png_imagep image; | |
1154 png_voidp buffer; | |
1155 png_int_32 row_stride; | |
1156 png_voidp colormap; | |
1157 png_const_colorp background; | |
1158 /* Local variables: */ | |
1159 png_voidp local_row; | |
1160 png_voidp first_row; | |
1161 ptrdiff_t row_bytes; /* step between rows */ | |
1162 int file_encoding; /* E_ values above */ | |
1163 png_fixed_point gamma_to_linear; /* For E_FILE, reciprocal of gamma */ | |
1164 int colormap_processing; /* PNG_CMAP_ values above */ | |
1165 } png_image_read_control; | |
1166 | |
1167 /* Do all the *safe* initialization - 'safe' means that png_error won't be | |
1168 * called, so setting up the jmp_buf is not required. This means that anything | |
1169 * called from here must *not* call png_malloc - it has to call png_malloc_warn | |
1170 * instead so that control is returned safely back to this routine. | |
1171 */ | |
1172 static int | |
1173 png_image_read_init(png_imagep image) | |
1174 { | |
1175 if (image->opaque == NULL) | |
1176 { | |
1177 png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, image, | |
1178 png_safe_error, png_safe_warning); | |
1179 | |
1180 /* And set the rest of the structure to NULL to ensure that the various | |
1181 * fields are consistent. | |
1182 */ | |
1183 memset(image, 0, (sizeof *image)); | |
1184 image->version = PNG_IMAGE_VERSION; | |
1185 | |
1186 if (png_ptr != NULL) | |
1187 { | |
1188 png_infop info_ptr = png_create_info_struct(png_ptr); | |
1189 | |
1190 if (info_ptr != NULL) | |
1191 { | |
1192 png_controlp control = png_voidcast(png_controlp, | |
1193 png_malloc_warn(png_ptr, (sizeof *control))); | |
1194 | |
1195 if (control != NULL) | |
1196 { | |
1197 memset(control, 0, (sizeof *control)); | |
1198 | |
1199 control->png_ptr = png_ptr; | |
1200 control->info_ptr = info_ptr; | |
1201 control->for_write = 0; | |
1202 | |
1203 image->opaque = control; | |
1204 return 1; | |
1205 } | |
1206 | |
1207 /* Error clean up */ | |
1208 png_destroy_info_struct(png_ptr, &info_ptr); | |
1209 } | |
1210 | |
1211 png_destroy_read_struct(&png_ptr, NULL, NULL); | |
1212 } | |
1213 | |
1214 return png_image_error(image, "png_image_read: out of memory"); | |
1215 } | |
1216 | |
1217 return png_image_error(image, "png_image_read: opaque pointer not NULL"); | |
1218 } | |
1219 | |
1220 /* Utility to find the base format of a PNG file from a png_struct. */ | |
1221 static png_uint_32 | |
1222 png_image_format(png_structrp png_ptr) | |
1223 { | |
1224 png_uint_32 format = 0; | |
1225 | |
1226 if (png_ptr->color_type & PNG_COLOR_MASK_COLOR) | |
1227 format |= PNG_FORMAT_FLAG_COLOR; | |
1228 | |
1229 if (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) | |
1230 format |= PNG_FORMAT_FLAG_ALPHA; | |
1231 | |
1232 /* Use png_ptr here, not info_ptr, because by examination png_handle_tRNS | |
1233 * sets the png_struct fields; that's all we are interested in here. The | |
1234 * precise interaction with an app call to png_set_tRNS and PNG file reading | |
1235 * is unclear. | |
1236 */ | |
1237 else if (png_ptr->num_trans > 0) | |
1238 format |= PNG_FORMAT_FLAG_ALPHA; | |
1239 | |
1240 if (png_ptr->bit_depth == 16) | |
1241 format |= PNG_FORMAT_FLAG_LINEAR; | |
1242 | |
1243 if (png_ptr->color_type & PNG_COLOR_MASK_PALETTE) | |
1244 format |= PNG_FORMAT_FLAG_COLORMAP; | |
1245 | |
1246 return format; | |
1247 } | |
1248 | |
1249 /* Is the given gamma significantly different from sRGB? The test is the same | |
1250 * one used in pngrtran.c when deciding whether to do gamma correction. The | |
1251 * arithmetic optimizes the division by using the fact that the inverse of the | |
1252 * file sRGB gamma is 2.2 | |
1253 */ | |
1254 static int | |
1255 png_gamma_not_sRGB(png_fixed_point g) | |
1256 { | |
1257 if (g < PNG_FP_1) | |
1258 { | |
1259 /* An uninitialized gamma is assumed to be sRGB for the simplified API. */ | |
1260 if (g == 0) | |
1261 return 0; | |
1262 | |
1263 return png_gamma_significant((g * 11 + 2)/5 /* i.e. *2.2, rounded */); | |
1264 } | |
1265 | |
1266 return 1; | |
1267 } | |
1268 | |
1269 /* Do the main body of a 'png_image_begin_read' function; read the PNG file | |
1270 * header and fill in all the information. This is executed in a safe context, | |
1271 * unlike the init routine above. | |
1272 */ | |
1273 static int | |
1274 png_image_read_header(png_voidp argument) | |
1275 { | |
1276 png_imagep image = png_voidcast(png_imagep, argument); | |
1277 png_structrp png_ptr = image->opaque->png_ptr; | |
1278 png_inforp info_ptr = image->opaque->info_ptr; | |
1279 | |
1280 png_set_benign_errors(png_ptr, 1/*warn*/); | |
1281 png_read_info(png_ptr, info_ptr); | |
1282 | |
1283 /* Do this the fast way; just read directly out of png_struct. */ | |
1284 image->width = png_ptr->width; | |
1285 image->height = png_ptr->height; | |
1286 | |
1287 { | |
1288 png_uint_32 format = png_image_format(png_ptr); | |
1289 | |
1290 image->format = format; | |
1291 | |
1292 #ifdef PNG_COLORSPACE_SUPPORTED | |
1293 /* Does the colorspace match sRGB? If there is no color endpoint | |
1294 * (colorant) information assume yes, otherwise require the | |
1295 * 'ENDPOINTS_MATCHE_sRGB' colorspace flag to have been set. If the | |
1296 * colorspace has been determined to be invalid ignore it. | |
1297 */ | |
1298 if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && ((png_ptr->colorspace.flags | |
1299 & (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB| | |
1300 PNG_COLORSPACE_INVALID)) == PNG_COLORSPACE_HAVE_ENDPOINTS)) | |
1301 image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB; | |
1302 #endif | |
1303 } | |
1304 | |
1305 /* We need the maximum number of entries regardless of the format the | |
1306 * application sets here. | |
1307 */ | |
1308 { | |
1309 png_uint_32 cmap_entries; | |
1310 | |
1311 switch (png_ptr->color_type) | |
1312 { | |
1313 case PNG_COLOR_TYPE_GRAY: | |
1314 cmap_entries = 1U << png_ptr->bit_depth; | |
1315 break; | |
1316 | |
1317 case PNG_COLOR_TYPE_PALETTE: | |
1318 cmap_entries = png_ptr->num_palette; | |
1319 break; | |
1320 | |
1321 default: | |
1322 cmap_entries = 256; | |
1323 break; | |
1324 } | |
1325 | |
1326 if (cmap_entries > 256) | |
1327 cmap_entries = 256; | |
1328 | |
1329 image->colormap_entries = cmap_entries; | |
1330 } | |
1331 | |
1332 return 1; | |
1333 } | |
1334 | |
1335 #ifdef PNG_STDIO_SUPPORTED | |
1336 int PNGAPI | |
1337 png_image_begin_read_from_stdio(png_imagep image, FILE* file) | |
1338 { | |
1339 if (image != NULL && image->version == PNG_IMAGE_VERSION) | |
1340 { | |
1341 if (file != NULL) | |
1342 { | |
1343 if (png_image_read_init(image)) | |
1344 { | |
1345 /* This is slightly evil, but png_init_io doesn't do anything other | |
1346 * than this and we haven't changed the standard IO functions so | |
1347 * this saves a 'safe' function. | |
1348 */ | |
1349 image->opaque->png_ptr->io_ptr = file; | |
1350 return png_safe_execute(image, png_image_read_header, image); | |
1351 } | |
1352 } | |
1353 | |
1354 else | |
1355 return png_image_error(image, | |
1356 "png_image_begin_read_from_stdio: invalid argument"); | |
1357 } | |
1358 | |
1359 else if (image != NULL) | |
1360 return png_image_error(image, | |
1361 "png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION"); | |
1362 | |
1363 return 0; | |
1364 } | |
1365 | |
1366 int PNGAPI | |
1367 png_image_begin_read_from_file(png_imagep image, const char *file_name) | |
1368 { | |
1369 if (image != NULL && image->version == PNG_IMAGE_VERSION) | |
1370 { | |
1371 if (file_name != NULL) | |
1372 { | |
1373 FILE *fp = fopen(file_name, "rb"); | |
1374 | |
1375 if (fp != NULL) | |
1376 { | |
1377 if (png_image_read_init(image)) | |
1378 { | |
1379 image->opaque->png_ptr->io_ptr = fp; | |
1380 image->opaque->owned_file = 1; | |
1381 return png_safe_execute(image, png_image_read_header, image); | |
1382 } | |
1383 | |
1384 /* Clean up: just the opened file. */ | |
1385 (void)fclose(fp); | |
1386 } | |
1387 | |
1388 else | |
1389 return png_image_error(image, strerror(errno)); | |
1390 } | |
1391 | |
1392 else | |
1393 return png_image_error(image, | |
1394 "png_image_begin_read_from_file: invalid argument"); | |
1395 } | |
1396 | |
1397 else if (image != NULL) | |
1398 return png_image_error(image, | |
1399 "png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION"); | |
1400 | |
1401 return 0; | |
1402 } | |
1403 #endif /* PNG_STDIO_SUPPORTED */ | |
1404 | |
1405 static void PNGCBAPI | |
1406 png_image_memory_read(png_structp png_ptr, png_bytep out, png_size_t need) | |
1407 { | |
1408 if (png_ptr != NULL) | |
1409 { | |
1410 png_imagep image = png_voidcast(png_imagep, png_ptr->io_ptr); | |
1411 if (image != NULL) | |
1412 { | |
1413 png_controlp cp = image->opaque; | |
1414 if (cp != NULL) | |
1415 { | |
1416 png_const_bytep memory = cp->memory; | |
1417 png_size_t size = cp->size; | |
1418 | |
1419 if (memory != NULL && size >= need) | |
1420 { | |
1421 memcpy(out, memory, need); | |
1422 cp->memory = memory + need; | |
1423 cp->size = size - need; | |
1424 return; | |
1425 } | |
1426 | |
1427 png_error(png_ptr, "read beyond end of data"); | |
1428 } | |
1429 } | |
1430 | |
1431 png_error(png_ptr, "invalid memory read"); | |
1432 } | |
1433 } | |
1434 | |
1435 int PNGAPI png_image_begin_read_from_memory(png_imagep image, | |
1436 png_const_voidp memory, png_size_t size) | |
1437 { | |
1438 if (image != NULL && image->version == PNG_IMAGE_VERSION) | |
1439 { | |
1440 if (memory != NULL && size > 0) | |
1441 { | |
1442 if (png_image_read_init(image)) | |
1443 { | |
1444 /* Now set the IO functions to read from the memory buffer and | |
1445 * store it into io_ptr. Again do this in-place to avoid calling a | |
1446 * libpng function that requires error handling. | |
1447 */ | |
1448 image->opaque->memory = png_voidcast(png_const_bytep, memory); | |
1449 image->opaque->size = size; | |
1450 image->opaque->png_ptr->io_ptr = image; | |
1451 image->opaque->png_ptr->read_data_fn = png_image_memory_read; | |
1452 | |
1453 return png_safe_execute(image, png_image_read_header, image); | |
1454 } | |
1455 } | |
1456 | |
1457 else | |
1458 return png_image_error(image, | |
1459 "png_image_begin_read_from_memory: invalid argument"); | |
1460 } | |
1461 | |
1462 else if (image != NULL) | |
1463 return png_image_error(image, | |
1464 "png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION"); | |
1465 | |
1466 return 0; | |
1467 } | |
1468 | |
1469 /* Utility function to skip chunks that are not used by the simplified image | |
1470 * read functions and an appropriate macro to call it. | |
1471 */ | |
1472 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED | |
1473 static void | |
1474 png_image_skip_unused_chunks(png_structrp png_ptr) | |
1475 { | |
1476 /* Prepare the reader to ignore all recognized chunks whose data will not | |
1477 * be used, i.e., all chunks recognized by libpng except for those | |
1478 * involved in basic image reading: | |
1479 * | |
1480 * IHDR, PLTE, IDAT, IEND | |
1481 * | |
1482 * Or image data handling: | |
1483 * | |
1484 * tRNS, bKGD, gAMA, cHRM, sRGB, iCCP and sBIT. | |
1485 * | |
1486 * This provides a small performance improvement and eliminates any | |
1487 * potential vulnerability to security problems in the unused chunks. | |
1488 */ | |
1489 { | |
1490 static PNG_CONST png_byte chunks_to_process[] = { | |
1491 98, 75, 71, 68, '\0', /* bKGD */ | |
1492 99, 72, 82, 77, '\0', /* cHRM */ | |
1493 103, 65, 77, 65, '\0', /* gAMA */ | |
1494 105, 67, 67, 80, '\0', /* iCCP */ | |
1495 115, 66, 73, 84, '\0', /* sBIT */ | |
1496 115, 82, 71, 66, '\0', /* sRGB */ | |
1497 }; | |
1498 | |
1499 /* Ignore unknown chunks and all other chunks except for the | |
1500 * IHDR, PLTE, tRNS, IDAT, and IEND chunks. | |
1501 */ | |
1502 png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_NEVER, | |
1503 NULL, -1); | |
1504 | |
1505 /* But do not ignore image data handling chunks */ | |
1506 png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_AS_DEFAULT, | |
1507 chunks_to_process, (sizeof chunks_to_process)/5); | |
1508 } | |
1509 } | |
1510 | |
1511 # define PNG_SKIP_CHUNKS(p) png_image_skip_unused_chunks(p) | |
1512 #else | |
1513 # define PNG_SKIP_CHUNKS(p) ((void)0) | |
1514 #endif /* PNG_HANDLE_AS_UNKNOWN_SUPPORTED */ | |
1515 | |
1516 /* The following macro gives the exact rounded answer for all values in the | |
1517 * range 0..255 (it actually divides by 51.2, but the rounding still generates | |
1518 * the correct numbers 0..5 | |
1519 */ | |
1520 #define PNG_DIV51(v8) (((v8) * 5 + 130) >> 8) | |
1521 | |
1522 /* Utility functions to make particular color-maps */ | |
1523 static void | |
1524 set_file_encoding(png_image_read_control *display) | |
1525 { | |
1526 png_fixed_point g = display->image->opaque->png_ptr->colorspace.gamma; | |
1527 if (png_gamma_significant(g)) | |
1528 { | |
1529 if (png_gamma_not_sRGB(g)) | |
1530 { | |
1531 display->file_encoding = E_FILE; | |
1532 display->gamma_to_linear = png_reciprocal(g); | |
1533 } | |
1534 | |
1535 else | |
1536 display->file_encoding = E_sRGB; | |
1537 } | |
1538 | |
1539 else | |
1540 display->file_encoding = E_LINEAR8; | |
1541 } | |
1542 | |
1543 static unsigned int | |
1544 decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding) | |
1545 { | |
1546 if (encoding == E_FILE) /* double check */ | |
1547 encoding = display->file_encoding; | |
1548 | |
1549 if (encoding == E_NOTSET) /* must be the file encoding */ | |
1550 { | |
1551 set_file_encoding(display); | |
1552 encoding = display->file_encoding; | |
1553 } | |
1554 | |
1555 switch (encoding) | |
1556 { | |
1557 case E_FILE: | |
1558 value = png_gamma_16bit_correct(value*257, display->gamma_to_linear); | |
1559 break; | |
1560 | |
1561 case E_sRGB: | |
1562 value = png_sRGB_table[value]; | |
1563 break; | |
1564 | |
1565 case E_LINEAR: | |
1566 break; | |
1567 | |
1568 case E_LINEAR8: | |
1569 value *= 257; | |
1570 break; | |
1571 | |
1572 default: | |
1573 png_error(display->image->opaque->png_ptr, | |
1574 "unexpected encoding (internal error)"); | |
1575 break; | |
1576 } | |
1577 | |
1578 return value; | |
1579 } | |
1580 | |
1581 static png_uint_32 | |
1582 png_colormap_compose(png_image_read_control *display, | |
1583 png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha, | |
1584 png_uint_32 background, int encoding) | |
1585 { | |
1586 /* The file value is composed on the background, the background has the given | |
1587 * encoding and so does the result, the file is encoded with E_FILE and the | |
1588 * file and alpha are 8-bit values. The (output) encoding will always be | |
1589 * E_LINEAR or E_sRGB. | |
1590 */ | |
1591 png_uint_32 f = decode_gamma(display, foreground, foreground_encoding); | |
1592 png_uint_32 b = decode_gamma(display, background, encoding); | |
1593 | |
1594 /* The alpha is always an 8-bit value (it comes from the palette), the value | |
1595 * scaled by 255 is what PNG_sRGB_FROM_LINEAR requires. | |
1596 */ | |
1597 f = f * alpha + b * (255-alpha); | |
1598 | |
1599 if (encoding == E_LINEAR) | |
1600 { | |
1601 /* Scale to 65535; divide by 255, approximately (in fact this is extremely | |
1602 * accurate, it divides by 255.00000005937181414556, with no overflow.) | |
1603 */ | |
1604 f *= 257; /* Now scaled by 65535 */ | |
1605 f += f >> 16; | |
1606 f = (f+32768) >> 16; | |
1607 } | |
1608 | |
1609 else /* E_sRGB */ | |
1610 f = PNG_sRGB_FROM_LINEAR(f); | |
1611 | |
1612 return f; | |
1613 } | |
1614 | |
1615 /* NOTE: E_LINEAR values to this routine must be 16-bit, but E_FILE values must | |
1616 * be 8-bit. | |
1617 */ | |
1618 static void | |
1619 png_create_colormap_entry(png_image_read_control *display, | |
1620 png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue, | |
1621 png_uint_32 alpha, int encoding) | |
1622 { | |
1623 png_imagep image = display->image; | |
1624 const int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) ? | |
1625 E_LINEAR : E_sRGB; | |
1626 const int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 && | |
1627 (red != green || green != blue); | |
1628 | |
1629 if (ip > 255) | |
1630 png_error(image->opaque->png_ptr, "color-map index out of range"); | |
1631 | |
1632 /* Update the cache with whether the file gamma is significantly different | |
1633 * from sRGB. | |
1634 */ | |
1635 if (encoding == E_FILE) | |
1636 { | |
1637 if (display->file_encoding == E_NOTSET) | |
1638 set_file_encoding(display); | |
1639 | |
1640 /* Note that the cached value may be E_FILE too, but if it is then the | |
1641 * gamma_to_linear member has been set. | |
1642 */ | |
1643 encoding = display->file_encoding; | |
1644 } | |
1645 | |
1646 if (encoding == E_FILE) | |
1647 { | |
1648 png_fixed_point g = display->gamma_to_linear; | |
1649 | |
1650 red = png_gamma_16bit_correct(red*257, g); | |
1651 green = png_gamma_16bit_correct(green*257, g); | |
1652 blue = png_gamma_16bit_correct(blue*257, g); | |
1653 | |
1654 if (convert_to_Y || output_encoding == E_LINEAR) | |
1655 { | |
1656 alpha *= 257; | |
1657 encoding = E_LINEAR; | |
1658 } | |
1659 | |
1660 else | |
1661 { | |
1662 red = PNG_sRGB_FROM_LINEAR(red * 255); | |
1663 green = PNG_sRGB_FROM_LINEAR(green * 255); | |
1664 blue = PNG_sRGB_FROM_LINEAR(blue * 255); | |
1665 encoding = E_sRGB; | |
1666 } | |
1667 } | |
1668 | |
1669 else if (encoding == E_LINEAR8) | |
1670 { | |
1671 /* This encoding occurs quite frequently in test cases because PngSuite | |
1672 * includes a gAMA 1.0 chunk with most images. | |
1673 */ | |
1674 red *= 257; | |
1675 green *= 257; | |
1676 blue *= 257; | |
1677 alpha *= 257; | |
1678 encoding = E_LINEAR; | |
1679 } | |
1680 | |
1681 else if (encoding == E_sRGB && (convert_to_Y || output_encoding == E_LINEAR)) | |
1682 { | |
1683 /* The values are 8-bit sRGB values, but must be converted to 16-bit | |
1684 * linear. | |
1685 */ | |
1686 red = png_sRGB_table[red]; | |
1687 green = png_sRGB_table[green]; | |
1688 blue = png_sRGB_table[blue]; | |
1689 alpha *= 257; | |
1690 encoding = E_LINEAR; | |
1691 } | |
1692 | |
1693 /* This is set if the color isn't gray but the output is. */ | |
1694 if (encoding == E_LINEAR) | |
1695 { | |
1696 if (convert_to_Y) | |
1697 { | |
1698 /* NOTE: these values are copied from png_do_rgb_to_gray */ | |
1699 png_uint_32 y = (png_uint_32)6968 * red + (png_uint_32)23434 * green + | |
1700 (png_uint_32)2366 * blue; | |
1701 | |
1702 if (output_encoding == E_LINEAR) | |
1703 y = (y + 16384) >> 15; | |
1704 | |
1705 else | |
1706 { | |
1707 /* y is scaled by 32768, we need it scaled by 255: */ | |
1708 y = (y + 128) >> 8; | |
1709 y *= 255; | |
1710 y = PNG_sRGB_FROM_LINEAR((y + 64) >> 7); | |
1711 encoding = E_sRGB; | |
1712 } | |
1713 | |
1714 blue = red = green = y; | |
1715 } | |
1716 | |
1717 else if (output_encoding == E_sRGB) | |
1718 { | |
1719 red = PNG_sRGB_FROM_LINEAR(red * 255); | |
1720 green = PNG_sRGB_FROM_LINEAR(green * 255); | |
1721 blue = PNG_sRGB_FROM_LINEAR(blue * 255); | |
1722 alpha = PNG_DIV257(alpha); | |
1723 encoding = E_sRGB; | |
1724 } | |
1725 } | |
1726 | |
1727 if (encoding != output_encoding) | |
1728 png_error(image->opaque->png_ptr, "bad encoding (internal error)"); | |
1729 | |
1730 /* Store the value. */ | |
1731 { | |
1732 # ifdef PNG_FORMAT_BGR_SUPPORTED | |
1733 const int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 && | |
1734 (image->format & PNG_FORMAT_FLAG_ALPHA) != 0; | |
1735 # else | |
1736 # define afirst 0 | |
1737 # endif | |
1738 # ifdef PNG_FORMAT_BGR_SUPPORTED | |
1739 const int bgr = (image->format & PNG_FORMAT_FLAG_BGR) ? 2 : 0; | |
1740 # else | |
1741 # define bgr 0 | |
1742 # endif | |
1743 | |
1744 if (output_encoding == E_LINEAR) | |
1745 { | |
1746 png_uint_16p entry = png_voidcast(png_uint_16p, display->colormap); | |
1747 | |
1748 entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format); | |
1749 | |
1750 /* The linear 16-bit values must be pre-multiplied by the alpha channel | |
1751 * value, if less than 65535 (this is, effectively, composite on black | |
1752 * if the alpha channel is removed.) | |
1753 */ | |
1754 switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format)) | |
1755 { | |
1756 case 4: | |
1757 entry[afirst ? 0 : 3] = (png_uint_16)alpha; | |
1758 /* FALL THROUGH */ | |
1759 | |
1760 case 3: | |
1761 if (alpha < 65535) | |
1762 { | |
1763 if (alpha > 0) | |
1764 { | |
1765 blue = (blue * alpha + 32767U)/65535U; | |
1766 green = (green * alpha + 32767U)/65535U; | |
1767 red = (red * alpha + 32767U)/65535U; | |
1768 } | |
1769 | |
1770 else | |
1771 red = green = blue = 0; | |
1772 } | |
1773 entry[afirst + (2 ^ bgr)] = (png_uint_16)blue; | |
1774 entry[afirst + 1] = (png_uint_16)green; | |
1775 entry[afirst + bgr] = (png_uint_16)red; | |
1776 break; | |
1777 | |
1778 case 2: | |
1779 entry[1 ^ afirst] = (png_uint_16)alpha; | |
1780 /* FALL THROUGH */ | |
1781 | |
1782 case 1: | |
1783 if (alpha < 65535) | |
1784 { | |
1785 if (alpha > 0) | |
1786 green = (green * alpha + 32767U)/65535U; | |
1787 | |
1788 else | |
1789 green = 0; | |
1790 } | |
1791 entry[afirst] = (png_uint_16)green; | |
1792 break; | |
1793 | |
1794 default: | |
1795 break; | |
1796 } | |
1797 } | |
1798 | |
1799 else /* output encoding is E_sRGB */ | |
1800 { | |
1801 png_bytep entry = png_voidcast(png_bytep, display->colormap); | |
1802 | |
1803 entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format); | |
1804 | |
1805 switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format)) | |
1806 { | |
1807 case 4: | |
1808 entry[afirst ? 0 : 3] = (png_byte)alpha; | |
1809 case 3: | |
1810 entry[afirst + (2 ^ bgr)] = (png_byte)blue; | |
1811 entry[afirst + 1] = (png_byte)green; | |
1812 entry[afirst + bgr] = (png_byte)red; | |
1813 break; | |
1814 | |
1815 case 2: | |
1816 entry[1 ^ afirst] = (png_byte)alpha; | |
1817 case 1: | |
1818 entry[afirst] = (png_byte)green; | |
1819 break; | |
1820 | |
1821 default: | |
1822 break; | |
1823 } | |
1824 } | |
1825 | |
1826 # ifdef afirst | |
1827 # undef afirst | |
1828 # endif | |
1829 # ifdef bgr | |
1830 # undef bgr | |
1831 # endif | |
1832 } | |
1833 } | |
1834 | |
1835 static int | |
1836 make_gray_file_colormap(png_image_read_control *display) | |
1837 { | |
1838 unsigned int i; | |
1839 | |
1840 for (i=0; i<256; ++i) | |
1841 png_create_colormap_entry(display, i, i, i, i, 255, E_FILE); | |
1842 | |
1843 return i; | |
1844 } | |
1845 | |
1846 static int | |
1847 make_gray_colormap(png_image_read_control *display) | |
1848 { | |
1849 unsigned int i; | |
1850 | |
1851 for (i=0; i<256; ++i) | |
1852 png_create_colormap_entry(display, i, i, i, i, 255, E_sRGB); | |
1853 | |
1854 return i; | |
1855 } | |
1856 #define PNG_GRAY_COLORMAP_ENTRIES 256 | |
1857 | |
1858 static int | |
1859 make_ga_colormap(png_image_read_control *display) | |
1860 { | |
1861 unsigned int i, a; | |
1862 | |
1863 /* Alpha is retained, the output will be a color-map with entries | |
1864 * selected by six levels of alpha. One transparent entry, 6 gray | |
1865 * levels for all the intermediate alpha values, leaving 230 entries | |
1866 * for the opaque grays. The color-map entries are the six values | |
1867 * [0..5]*51, the GA processing uses PNG_DIV51(value) to find the | |
1868 * relevant entry. | |
1869 * | |
1870 * if (alpha > 229) // opaque | |
1871 * { | |
1872 * // The 231 entries are selected to make the math below work: | |
1873 * base = 0; | |
1874 * entry = (231 * gray + 128) >> 8; | |
1875 * } | |
1876 * else if (alpha < 26) // transparent | |
1877 * { | |
1878 * base = 231; | |
1879 * entry = 0; | |
1880 * } | |
1881 * else // partially opaque | |
1882 * { | |
1883 * base = 226 + 6 * PNG_DIV51(alpha); | |
1884 * entry = PNG_DIV51(gray); | |
1885 * } | |
1886 */ | |
1887 i = 0; | |
1888 while (i < 231) | |
1889 { | |
1890 unsigned int gray = (i * 256 + 115) / 231; | |
1891 png_create_colormap_entry(display, i++, gray, gray, gray, 255, E_sRGB); | |
1892 } | |
1893 | |
1894 /* 255 is used here for the component values for consistency with the code | |
1895 * that undoes premultiplication in pngwrite.c. | |
1896 */ | |
1897 png_create_colormap_entry(display, i++, 255, 255, 255, 0, E_sRGB); | |
1898 | |
1899 for (a=1; a<5; ++a) | |
1900 { | |
1901 unsigned int g; | |
1902 | |
1903 for (g=0; g<6; ++g) | |
1904 png_create_colormap_entry(display, i++, g*51, g*51, g*51, a*51, | |
1905 E_sRGB); | |
1906 } | |
1907 | |
1908 return i; | |
1909 } | |
1910 | |
1911 #define PNG_GA_COLORMAP_ENTRIES 256 | |
1912 | |
1913 static int | |
1914 make_rgb_colormap(png_image_read_control *display) | |
1915 { | |
1916 unsigned int i, r; | |
1917 | |
1918 /* Build a 6x6x6 opaque RGB cube */ | |
1919 for (i=r=0; r<6; ++r) | |
1920 { | |
1921 unsigned int g; | |
1922 | |
1923 for (g=0; g<6; ++g) | |
1924 { | |
1925 unsigned int b; | |
1926 | |
1927 for (b=0; b<6; ++b) | |
1928 png_create_colormap_entry(display, i++, r*51, g*51, b*51, 255, | |
1929 E_sRGB); | |
1930 } | |
1931 } | |
1932 | |
1933 return i; | |
1934 } | |
1935 | |
1936 #define PNG_RGB_COLORMAP_ENTRIES 216 | |
1937 | |
1938 /* Return a palette index to the above palette given three 8-bit sRGB values. */ | |
1939 #define PNG_RGB_INDEX(r,g,b) \ | |
1940 ((png_byte)(6 * (6 * PNG_DIV51(r) + PNG_DIV51(g)) + PNG_DIV51(b))) | |
1941 | |
1942 static int | |
1943 png_image_read_colormap(png_voidp argument) | |
1944 { | |
1945 png_image_read_control *display = | |
1946 png_voidcast(png_image_read_control*, argument); | |
1947 const png_imagep image = display->image; | |
1948 | |
1949 const png_structrp png_ptr = image->opaque->png_ptr; | |
1950 const png_uint_32 output_format = image->format; | |
1951 const int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) ? | |
1952 E_LINEAR : E_sRGB; | |
1953 | |
1954 unsigned int cmap_entries; | |
1955 unsigned int output_processing; /* Output processing option */ | |
1956 unsigned int data_encoding = E_NOTSET; /* Encoding libpng must produce */ | |
1957 | |
1958 /* Background information; the background color and the index of this color | |
1959 * in the color-map if it exists (else 256). | |
1960 */ | |
1961 unsigned int background_index = 256; | |
1962 png_uint_32 back_r, back_g, back_b; | |
1963 | |
1964 /* Flags to accumulate things that need to be done to the input. */ | |
1965 int expand_tRNS = 0; | |
1966 | |
1967 /* Exclude the NYI feature of compositing onto a color-mapped buffer; it is | |
1968 * very difficult to do, the results look awful, and it is difficult to see | |
1969 * what possible use it is because the application can't control the | |
1970 * color-map. | |
1971 */ | |
1972 if (((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0 || | |
1973 png_ptr->num_trans > 0) /* alpha in input */ && | |
1974 ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) /* no alpha in output */) | |
1975 { | |
1976 if (output_encoding == E_LINEAR) /* compose on black */ | |
1977 back_b = back_g = back_r = 0; | |
1978 | |
1979 else if (display->background == NULL /* no way to remove it */) | |
1980 png_error(png_ptr, | |
1981 "a background color must be supplied to remove alpha/transparency"); | |
1982 | |
1983 /* Get a copy of the background color (this avoids repeating the checks | |
1984 * below.) The encoding is 8-bit sRGB or 16-bit linear, depending on the | |
1985 * output format. | |
1986 */ | |
1987 else | |
1988 { | |
1989 back_g = display->background->green; | |
1990 if (output_format & PNG_FORMAT_FLAG_COLOR) | |
1991 { | |
1992 back_r = display->background->red; | |
1993 back_b = display->background->blue; | |
1994 } | |
1995 else | |
1996 back_b = back_r = back_g; | |
1997 } | |
1998 } | |
1999 | |
2000 else if (output_encoding == E_LINEAR) | |
2001 back_b = back_r = back_g = 65535; | |
2002 | |
2003 else | |
2004 back_b = back_r = back_g = 255; | |
2005 | |
2006 /* Default the input file gamma if required - this is necessary because | |
2007 * libpng assumes that if no gamma information is present the data is in the | |
2008 * output format, but the simplified API deduces the gamma from the input | |
2009 * format. | |
2010 */ | |
2011 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) == 0) | |
2012 { | |
2013 /* Do this directly, not using the png_colorspace functions, to ensure | |
2014 * that it happens even if the colorspace is invalid (though probably if | |
2015 * it is the setting will be ignored) Note that the same thing can be | |
2016 * achieved at the application interface with png_set_gAMA. | |
2017 */ | |
2018 if (png_ptr->bit_depth == 16 && | |
2019 (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0) | |
2020 png_ptr->colorspace.gamma = PNG_GAMMA_LINEAR; | |
2021 | |
2022 else | |
2023 png_ptr->colorspace.gamma = PNG_GAMMA_sRGB_INVERSE; | |
2024 | |
2025 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA; | |
2026 } | |
2027 | |
2028 /* Decide what to do based on the PNG color type of the input data. The | |
2029 * utility function png_create_colormap_entry deals with most aspects of the | |
2030 * output transformations; this code works out how to produce bytes of | |
2031 * color-map entries from the original format. | |
2032 */ | |
2033 switch (png_ptr->color_type) | |
2034 { | |
2035 case PNG_COLOR_TYPE_GRAY: | |
2036 if (png_ptr->bit_depth <= 8) | |
2037 { | |
2038 /* There at most 256 colors in the output, regardless of | |
2039 * transparency. | |
2040 */ | |
2041 unsigned int step, i, val, trans = 256/*ignore*/, back_alpha = 0; | |
2042 | |
2043 cmap_entries = 1U << png_ptr->bit_depth; | |
2044 if (cmap_entries > image->colormap_entries) | |
2045 png_error(png_ptr, "gray[8] color-map: too few entries"); | |
2046 | |
2047 step = 255 / (cmap_entries - 1); | |
2048 output_processing = PNG_CMAP_NONE; | |
2049 | |
2050 /* If there is a tRNS chunk then this either selects a transparent | |
2051 * value or, if the output has no alpha, the background color. | |
2052 */ | |
2053 if (png_ptr->num_trans > 0) | |
2054 { | |
2055 trans = png_ptr->trans_color.gray; | |
2056 | |
2057 if ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) | |
2058 back_alpha = output_encoding == E_LINEAR ? 65535 : 255; | |
2059 } | |
2060 | |
2061 /* png_create_colormap_entry just takes an RGBA and writes the | |
2062 * corresponding color-map entry using the format from 'image', | |
2063 * including the required conversion to sRGB or linear as | |
2064 * appropriate. The input values are always either sRGB (if the | |
2065 * gamma correction flag is 0) or 0..255 scaled file encoded values | |
2066 * (if the function must gamma correct them). | |
2067 */ | |
2068 for (i=val=0; i<cmap_entries; ++i, val += step) | |
2069 { | |
2070 /* 'i' is a file value. While this will result in duplicated | |
2071 * entries for 8-bit non-sRGB encoded files it is necessary to | |
2072 * have non-gamma corrected values to do tRNS handling. | |
2073 */ | |
2074 if (i != trans) | |
2075 png_create_colormap_entry(display, i, val, val, val, 255, | |
2076 E_FILE/*8-bit with file gamma*/); | |
2077 | |
2078 /* Else this entry is transparent. The colors don't matter if | |
2079 * there is an alpha channel (back_alpha == 0), but it does no | |
2080 * harm to pass them in; the values are not set above so this | |
2081 * passes in white. | |
2082 * | |
2083 * NOTE: this preserves the full precision of the application | |
2084 * supplied background color when it is used. | |
2085 */ | |
2086 else | |
2087 png_create_colormap_entry(display, i, back_r, back_g, back_b, | |
2088 back_alpha, output_encoding); | |
2089 } | |
2090 | |
2091 /* We need libpng to preserve the original encoding. */ | |
2092 data_encoding = E_FILE; | |
2093 | |
2094 /* The rows from libpng, while technically gray values, are now also | |
2095 * color-map indicies; however, they may need to be expanded to 1 | |
2096 * byte per pixel. This is what png_set_packing does (i.e., it | |
2097 * unpacks the bit values into bytes.) | |
2098 */ | |
2099 if (png_ptr->bit_depth < 8) | |
2100 png_set_packing(png_ptr); | |
2101 } | |
2102 | |
2103 else /* bit depth is 16 */ | |
2104 { | |
2105 /* The 16-bit input values can be converted directly to 8-bit gamma | |
2106 * encoded values; however, if a tRNS chunk is present 257 color-map | |
2107 * entries are required. This means that the extra entry requires | |
2108 * special processing; add an alpha channel, sacrifice gray level | |
2109 * 254 and convert transparent (alpha==0) entries to that. | |
2110 * | |
2111 * Use libpng to chop the data to 8 bits. Convert it to sRGB at the | |
2112 * same time to minimize quality loss. If a tRNS chunk is present | |
2113 * this means libpng must handle it too; otherwise it is impossible | |
2114 * to do the exact match on the 16-bit value. | |
2115 * | |
2116 * If the output has no alpha channel *and* the background color is | |
2117 * gray then it is possible to let libpng handle the substitution by | |
2118 * ensuring that the corresponding gray level matches the background | |
2119 * color exactly. | |
2120 */ | |
2121 data_encoding = E_sRGB; | |
2122 | |
2123 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries) | |
2124 png_error(png_ptr, "gray[16] color-map: too few entries"); | |
2125 | |
2126 cmap_entries = make_gray_colormap(display); | |
2127 | |
2128 if (png_ptr->num_trans > 0) | |
2129 { | |
2130 unsigned int back_alpha; | |
2131 | |
2132 if (output_format & PNG_FORMAT_FLAG_ALPHA) | |
2133 back_alpha = 0; | |
2134 | |
2135 else | |
2136 { | |
2137 if (back_r == back_g && back_g == back_b) | |
2138 { | |
2139 /* Background is gray; no special processing will be | |
2140 * required. | |
2141 */ | |
2142 png_color_16 c; | |
2143 png_uint_32 gray = back_g; | |
2144 | |
2145 if (output_encoding == E_LINEAR) | |
2146 { | |
2147 gray = PNG_sRGB_FROM_LINEAR(gray * 255); | |
2148 | |
2149 /* And make sure the corresponding palette entry | |
2150 * matches. | |
2151 */ | |
2152 png_create_colormap_entry(display, gray, back_g, back_g, | |
2153 back_g, 65535, E_LINEAR); | |
2154 } | |
2155 | |
2156 /* The background passed to libpng, however, must be the | |
2157 * sRGB value. | |
2158 */ | |
2159 c.index = 0; /*unused*/ | |
2160 c.gray = c.red = c.green = c.blue = (png_uint_16)gray; | |
2161 | |
2162 /* NOTE: does this work without expanding tRNS to alpha? | |
2163 * It should be the color->gray case below apparently | |
2164 * doesn't. | |
2165 */ | |
2166 png_set_background_fixed(png_ptr, &c, | |
2167 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, | |
2168 0/*gamma: not used*/); | |
2169 | |
2170 output_processing = PNG_CMAP_NONE; | |
2171 break; | |
2172 } | |
2173 | |
2174 back_alpha = output_encoding == E_LINEAR ? 65535 : 255; | |
2175 } | |
2176 | |
2177 /* output_processing means that the libpng-processed row will be | |
2178 * 8-bit GA and it has to be processing to single byte color-map | |
2179 * values. Entry 254 is replaced by either a completely | |
2180 * transparent entry or by the background color at full | |
2181 * precision (and the background color is not a simple gray leve | |
2182 * in this case.) | |
2183 */ | |
2184 expand_tRNS = 1; | |
2185 output_processing = PNG_CMAP_TRANS; | |
2186 background_index = 254; | |
2187 | |
2188 /* And set (overwrite) color-map entry 254 to the actual | |
2189 * background color at full precision. | |
2190 */ | |
2191 png_create_colormap_entry(display, 254, back_r, back_g, back_b, | |
2192 back_alpha, output_encoding); | |
2193 } | |
2194 | |
2195 else | |
2196 output_processing = PNG_CMAP_NONE; | |
2197 } | |
2198 break; | |
2199 | |
2200 case PNG_COLOR_TYPE_GRAY_ALPHA: | |
2201 /* 8-bit or 16-bit PNG with two channels - gray and alpha. A minimum | |
2202 * of 65536 combinations. If, however, the alpha channel is to be | |
2203 * removed there are only 256 possibilities if the background is gray. | |
2204 * (Otherwise there is a subset of the 65536 possibilities defined by | |
2205 * the triangle between black, white and the background color.) | |
2206 * | |
2207 * Reduce 16-bit files to 8-bit and sRGB encode the result. No need to | |
2208 * worry about tRNS matching - tRNS is ignored if there is an alpha | |
2209 * channel. | |
2210 */ | |
2211 data_encoding = E_sRGB; | |
2212 | |
2213 if (output_format & PNG_FORMAT_FLAG_ALPHA) | |
2214 { | |
2215 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries) | |
2216 png_error(png_ptr, "gray+alpha color-map: too few entries"); | |
2217 | |
2218 cmap_entries = make_ga_colormap(display); | |
2219 | |
2220 background_index = PNG_CMAP_GA_BACKGROUND; | |
2221 output_processing = PNG_CMAP_GA; | |
2222 } | |
2223 | |
2224 else /* alpha is removed */ | |
2225 { | |
2226 /* Alpha must be removed as the PNG data is processed when the | |
2227 * background is a color because the G and A channels are | |
2228 * independent and the vector addition (non-parallel vectors) is a | |
2229 * 2-D problem. | |
2230 * | |
2231 * This can be reduced to the same algorithm as above by making a | |
2232 * colormap containing gray levels (for the opaque grays), a | |
2233 * background entry (for a transparent pixel) and a set of four six | |
2234 * level color values, one set for each intermediate alpha value. | |
2235 * See the comments in make_ga_colormap for how this works in the | |
2236 * per-pixel processing. | |
2237 * | |
2238 * If the background is gray, however, we only need a 256 entry gray | |
2239 * level color map. It is sufficient to make the entry generated | |
2240 * for the background color be exactly the color specified. | |
2241 */ | |
2242 if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0 || | |
2243 (back_r == back_g && back_g == back_b)) | |
2244 { | |
2245 /* Background is gray; no special processing will be required. */ | |
2246 png_color_16 c; | |
2247 png_uint_32 gray = back_g; | |
2248 | |
2249 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries) | |
2250 png_error(png_ptr, "gray-alpha color-map: too few entries"); | |
2251 | |
2252 cmap_entries = make_gray_colormap(display); | |
2253 | |
2254 if (output_encoding == E_LINEAR) | |
2255 { | |
2256 gray = PNG_sRGB_FROM_LINEAR(gray * 255); | |
2257 | |
2258 /* And make sure the corresponding palette entry matches. */ | |
2259 png_create_colormap_entry(display, gray, back_g, back_g, | |
2260 back_g, 65535, E_LINEAR); | |
2261 } | |
2262 | |
2263 /* The background passed to libpng, however, must be the sRGB | |
2264 * value. | |
2265 */ | |
2266 c.index = 0; /*unused*/ | |
2267 c.gray = c.red = c.green = c.blue = (png_uint_16)gray; | |
2268 | |
2269 png_set_background_fixed(png_ptr, &c, | |
2270 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, | |
2271 0/*gamma: not used*/); | |
2272 | |
2273 output_processing = PNG_CMAP_NONE; | |
2274 } | |
2275 | |
2276 else | |
2277 { | |
2278 png_uint_32 i, a; | |
2279 | |
2280 /* This is the same as png_make_ga_colormap, above, except that | |
2281 * the entries are all opaque. | |
2282 */ | |
2283 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries) | |
2284 png_error(png_ptr, "ga-alpha color-map: too few entries"); | |
2285 | |
2286 i = 0; | |
2287 while (i < 231) | |
2288 { | |
2289 png_uint_32 gray = (i * 256 + 115) / 231; | |
2290 png_create_colormap_entry(display, i++, gray, gray, gray, | |
2291 255, E_sRGB); | |
2292 } | |
2293 | |
2294 /* NOTE: this preserves the full precision of the application | |
2295 * background color. | |
2296 */ | |
2297 background_index = i; | |
2298 png_create_colormap_entry(display, i++, back_r, back_g, back_b, | |
2299 output_encoding == E_LINEAR ? 65535U : 255U, output_encoding); | |
2300 | |
2301 /* For non-opaque input composite on the sRGB background - this | |
2302 * requires inverting the encoding for each component. The input | |
2303 * is still converted to the sRGB encoding because this is a | |
2304 * reasonable approximate to the logarithmic curve of human | |
2305 * visual sensitivity, at least over the narrow range which PNG | |
2306 * represents. Consequently 'G' is always sRGB encoded, while | |
2307 * 'A' is linear. We need the linear background colors. | |
2308 */ | |
2309 if (output_encoding == E_sRGB) /* else already linear */ | |
2310 { | |
2311 /* This may produce a value not exactly matching the | |
2312 * background, but that's ok because these numbers are only | |
2313 * used when alpha != 0 | |
2314 */ | |
2315 back_r = png_sRGB_table[back_r]; | |
2316 back_g = png_sRGB_table[back_g]; | |
2317 back_b = png_sRGB_table[back_b]; | |
2318 } | |
2319 | |
2320 for (a=1; a<5; ++a) | |
2321 { | |
2322 unsigned int g; | |
2323 | |
2324 /* PNG_sRGB_FROM_LINEAR expects a 16-bit linear value scaled | |
2325 * by an 8-bit alpha value (0..255). | |
2326 */ | |
2327 png_uint_32 alpha = 51 * a; | |
2328 png_uint_32 back_rx = (255-alpha) * back_r; | |
2329 png_uint_32 back_gx = (255-alpha) * back_g; | |
2330 png_uint_32 back_bx = (255-alpha) * back_b; | |
2331 | |
2332 for (g=0; g<6; ++g) | |
2333 { | |
2334 png_uint_32 gray = png_sRGB_table[g*51] * alpha; | |
2335 | |
2336 png_create_colormap_entry(display, i++, | |
2337 PNG_sRGB_FROM_LINEAR(gray + back_rx), | |
2338 PNG_sRGB_FROM_LINEAR(gray + back_gx), | |
2339 PNG_sRGB_FROM_LINEAR(gray + back_bx), 255, E_sRGB); | |
2340 } | |
2341 } | |
2342 | |
2343 cmap_entries = i; | |
2344 output_processing = PNG_CMAP_GA; | |
2345 } | |
2346 } | |
2347 break; | |
2348 | |
2349 case PNG_COLOR_TYPE_RGB: | |
2350 case PNG_COLOR_TYPE_RGB_ALPHA: | |
2351 /* Exclude the case where the output is gray; we can always handle this | |
2352 * with the cases above. | |
2353 */ | |
2354 if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0) | |
2355 { | |
2356 /* The color-map will be grayscale, so we may as well convert the | |
2357 * input RGB values to a simple grayscale and use the grayscale | |
2358 * code above. | |
2359 * | |
2360 * NOTE: calling this apparently damages the recognition of the | |
2361 * transparent color in background color handling; call | |
2362 * png_set_tRNS_to_alpha before png_set_background_fixed. | |
2363 */ | |
2364 png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, -1, | |
2365 -1); | |
2366 data_encoding = E_sRGB; | |
2367 | |
2368 /* The output will now be one or two 8-bit gray or gray+alpha | |
2369 * channels. The more complex case arises when the input has alpha. | |
2370 */ | |
2371 if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || | |
2372 png_ptr->num_trans > 0) && | |
2373 (output_format & PNG_FORMAT_FLAG_ALPHA) != 0) | |
2374 { | |
2375 /* Both input and output have an alpha channel, so no background | |
2376 * processing is required; just map the GA bytes to the right | |
2377 * color-map entry. | |
2378 */ | |
2379 expand_tRNS = 1; | |
2380 | |
2381 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries) | |
2382 png_error(png_ptr, "rgb[ga] color-map: too few entries"); | |
2383 | |
2384 cmap_entries = make_ga_colormap(display); | |
2385 background_index = PNG_CMAP_GA_BACKGROUND; | |
2386 output_processing = PNG_CMAP_GA; | |
2387 } | |
2388 | |
2389 else | |
2390 { | |
2391 /* Either the input or the output has no alpha channel, so there | |
2392 * will be no non-opaque pixels in the color-map; it will just be | |
2393 * grayscale. | |
2394 */ | |
2395 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries) | |
2396 png_error(png_ptr, "rgb[gray] color-map: too few entries"); | |
2397 | |
2398 /* Ideally this code would use libpng to do the gamma correction, | |
2399 * but if an input alpha channel is to be removed we will hit the | |
2400 * libpng bug in gamma+compose+rgb-to-gray (the double gamma | |
2401 * correction bug). Fix this by dropping the gamma correction in | |
2402 * this case and doing it in the palette; this will result in | |
2403 * duplicate palette entries, but that's better than the | |
2404 * alternative of double gamma correction. | |
2405 */ | |
2406 if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || | |
2407 png_ptr->num_trans > 0) && | |
2408 png_gamma_not_sRGB(png_ptr->colorspace.gamma)) | |
2409 { | |
2410 cmap_entries = make_gray_file_colormap(display); | |
2411 data_encoding = E_FILE; | |
2412 } | |
2413 | |
2414 else | |
2415 cmap_entries = make_gray_colormap(display); | |
2416 | |
2417 /* But if the input has alpha or transparency it must be removed | |
2418 */ | |
2419 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || | |
2420 png_ptr->num_trans > 0) | |
2421 { | |
2422 png_color_16 c; | |
2423 png_uint_32 gray = back_g; | |
2424 | |
2425 /* We need to ensure that the application background exists in | |
2426 * the colormap and that completely transparent pixels map to | |
2427 * it. Achieve this simply by ensuring that the entry | |
2428 * selected for the background really is the background color. | |
2429 */ | |
2430 if (data_encoding == E_FILE) /* from the fixup above */ | |
2431 { | |
2432 /* The app supplied a gray which is in output_encoding, we | |
2433 * need to convert it to a value of the input (E_FILE) | |
2434 * encoding then set this palette entry to the required | |
2435 * output encoding. | |
2436 */ | |
2437 if (output_encoding == E_sRGB) | |
2438 gray = png_sRGB_table[gray]; /* now E_LINEAR */ | |
2439 | |
2440 gray = PNG_DIV257(png_gamma_16bit_correct(gray, | |
2441 png_ptr->colorspace.gamma)); /* now E_FILE */ | |
2442 | |
2443 /* And make sure the corresponding palette entry contains | |
2444 * exactly the required sRGB value. | |
2445 */ | |
2446 png_create_colormap_entry(display, gray, back_g, back_g, | |
2447 back_g, 0/*unused*/, output_encoding); | |
2448 } | |
2449 | |
2450 else if (output_encoding == E_LINEAR) | |
2451 { | |
2452 gray = PNG_sRGB_FROM_LINEAR(gray * 255); | |
2453 | |
2454 /* And make sure the corresponding palette entry matches. | |
2455 */ | |
2456 png_create_colormap_entry(display, gray, back_g, back_g, | |
2457 back_g, 0/*unused*/, E_LINEAR); | |
2458 } | |
2459 | |
2460 /* The background passed to libpng, however, must be the | |
2461 * output (normally sRGB) value. | |
2462 */ | |
2463 c.index = 0; /*unused*/ | |
2464 c.gray = c.red = c.green = c.blue = (png_uint_16)gray; | |
2465 | |
2466 /* NOTE: the following is apparently a bug in libpng. Without | |
2467 * it the transparent color recognition in | |
2468 * png_set_background_fixed seems to go wrong. | |
2469 */ | |
2470 expand_tRNS = 1; | |
2471 png_set_background_fixed(png_ptr, &c, | |
2472 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, | |
2473 0/*gamma: not used*/); | |
2474 } | |
2475 | |
2476 output_processing = PNG_CMAP_NONE; | |
2477 } | |
2478 } | |
2479 | |
2480 else /* output is color */ | |
2481 { | |
2482 /* We could use png_quantize here so long as there is no transparent | |
2483 * color or alpha; png_quantize ignores alpha. Easier overall just | |
2484 * to do it once and using PNG_DIV51 on the 6x6x6 reduced RGB cube. | |
2485 * Consequently we always want libpng to produce sRGB data. | |
2486 */ | |
2487 data_encoding = E_sRGB; | |
2488 | |
2489 /* Is there any transparency or alpha? */ | |
2490 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || | |
2491 png_ptr->num_trans > 0) | |
2492 { | |
2493 /* Is there alpha in the output too? If so all four channels are | |
2494 * processed into a special RGB cube with alpha support. | |
2495 */ | |
2496 if (output_format & PNG_FORMAT_FLAG_ALPHA) | |
2497 { | |
2498 png_uint_32 r; | |
2499 | |
2500 if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries) | |
2501 png_error(png_ptr, "rgb+alpha color-map: too few entries"); | |
2502 | |
2503 cmap_entries = make_rgb_colormap(display); | |
2504 | |
2505 /* Add a transparent entry. */ | |
2506 png_create_colormap_entry(display, cmap_entries, 255, 255, | |
2507 255, 0, E_sRGB); | |
2508 | |
2509 /* This is stored as the background index for the processing | |
2510 * algorithm. | |
2511 */ | |
2512 background_index = cmap_entries++; | |
2513 | |
2514 /* Add 27 r,g,b entries each with alpha 0.5. */ | |
2515 for (r=0; r<256; r = (r << 1) | 0x7f) | |
2516 { | |
2517 png_uint_32 g; | |
2518 | |
2519 for (g=0; g<256; g = (g << 1) | 0x7f) | |
2520 { | |
2521 png_uint_32 b; | |
2522 | |
2523 /* This generates components with the values 0, 127 and | |
2524 * 255 | |
2525 */ | |
2526 for (b=0; b<256; b = (b << 1) | 0x7f) | |
2527 png_create_colormap_entry(display, cmap_entries++, | |
2528 r, g, b, 128, E_sRGB); | |
2529 } | |
2530 } | |
2531 | |
2532 expand_tRNS = 1; | |
2533 output_processing = PNG_CMAP_RGB_ALPHA; | |
2534 } | |
2535 | |
2536 else | |
2537 { | |
2538 /* Alpha/transparency must be removed. The background must | |
2539 * exist in the color map (achieved by setting adding it after | |
2540 * the 666 color-map). If the standard processing code will | |
2541 * pick up this entry automatically that's all that is | |
2542 * required; libpng can be called to do the background | |
2543 * processing. | |
2544 */ | |
2545 unsigned int sample_size = | |
2546 PNG_IMAGE_SAMPLE_SIZE(output_format); | |
2547 png_uint_32 r, g, b; /* sRGB background */ | |
2548 | |
2549 if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries) | |
2550 png_error(png_ptr, "rgb-alpha color-map: too few entries"); | |
2551 | |
2552 cmap_entries = make_rgb_colormap(display); | |
2553 | |
2554 png_create_colormap_entry(display, cmap_entries, back_r, | |
2555 back_g, back_b, 0/*unused*/, output_encoding); | |
2556 | |
2557 if (output_encoding == E_LINEAR) | |
2558 { | |
2559 r = PNG_sRGB_FROM_LINEAR(back_r * 255); | |
2560 g = PNG_sRGB_FROM_LINEAR(back_g * 255); | |
2561 b = PNG_sRGB_FROM_LINEAR(back_b * 255); | |
2562 } | |
2563 | |
2564 else | |
2565 { | |
2566 r = back_r; | |
2567 g = back_g; | |
2568 b = back_g; | |
2569 } | |
2570 | |
2571 /* Compare the newly-created color-map entry with the one the | |
2572 * PNG_CMAP_RGB algorithm will use. If the two entries don't | |
2573 * match, add the new one and set this as the background | |
2574 * index. | |
2575 */ | |
2576 if (memcmp((png_const_bytep)display->colormap + | |
2577 sample_size * cmap_entries, | |
2578 (png_const_bytep)display->colormap + | |
2579 sample_size * PNG_RGB_INDEX(r,g,b), | |
2580 sample_size) != 0) | |
2581 { | |
2582 /* The background color must be added. */ | |
2583 background_index = cmap_entries++; | |
2584 | |
2585 /* Add 27 r,g,b entries each with created by composing with | |
2586 * the background at alpha 0.5. | |
2587 */ | |
2588 for (r=0; r<256; r = (r << 1) | 0x7f) | |
2589 { | |
2590 for (g=0; g<256; g = (g << 1) | 0x7f) | |
2591 { | |
2592 /* This generates components with the values 0, 127 | |
2593 * and 255 | |
2594 */ | |
2595 for (b=0; b<256; b = (b << 1) | 0x7f) | |
2596 png_create_colormap_entry(display, cmap_entries++, | |
2597 png_colormap_compose(display, r, E_sRGB, 128, | |
2598 back_r, output_encoding), | |
2599 png_colormap_compose(display, g, E_sRGB, 128, | |
2600 back_g, output_encoding), | |
2601 png_colormap_compose(display, b, E_sRGB, 128, | |
2602 back_b, output_encoding), | |
2603 0/*unused*/, output_encoding); | |
2604 } | |
2605 } | |
2606 | |
2607 expand_tRNS = 1; | |
2608 output_processing = PNG_CMAP_RGB_ALPHA; | |
2609 } | |
2610 | |
2611 else /* background color is in the standard color-map */ | |
2612 { | |
2613 png_color_16 c; | |
2614 | |
2615 c.index = 0; /*unused*/ | |
2616 c.red = (png_uint_16)back_r; | |
2617 c.gray = c.green = (png_uint_16)back_g; | |
2618 c.blue = (png_uint_16)back_b; | |
2619 | |
2620 png_set_background_fixed(png_ptr, &c, | |
2621 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, | |
2622 0/*gamma: not used*/); | |
2623 | |
2624 output_processing = PNG_CMAP_RGB; | |
2625 } | |
2626 } | |
2627 } | |
2628 | |
2629 else /* no alpha or transparency in the input */ | |
2630 { | |
2631 /* Alpha in the output is irrelevant, simply map the opaque input | |
2632 * pixels to the 6x6x6 color-map. | |
2633 */ | |
2634 if (PNG_RGB_COLORMAP_ENTRIES > image->colormap_entries) | |
2635 png_error(png_ptr, "rgb color-map: too few entries"); | |
2636 | |
2637 cmap_entries = make_rgb_colormap(display); | |
2638 output_processing = PNG_CMAP_RGB; | |
2639 } | |
2640 } | |
2641 break; | |
2642 | |
2643 case PNG_COLOR_TYPE_PALETTE: | |
2644 /* It's already got a color-map. It may be necessary to eliminate the | |
2645 * tRNS entries though. | |
2646 */ | |
2647 { | |
2648 unsigned int num_trans = png_ptr->num_trans; | |
2649 png_const_bytep trans = num_trans > 0 ? png_ptr->trans_alpha : NULL; | |
2650 png_const_colorp colormap = png_ptr->palette; | |
2651 const int do_background = trans != NULL && | |
2652 (output_format & PNG_FORMAT_FLAG_ALPHA) == 0; | |
2653 unsigned int i; | |
2654 | |
2655 /* Just in case: */ | |
2656 if (trans == NULL) | |
2657 num_trans = 0; | |
2658 | |
2659 output_processing = PNG_CMAP_NONE; | |
2660 data_encoding = E_FILE; /* Don't change from color-map indicies */ | |
2661 cmap_entries = png_ptr->num_palette; | |
2662 if (cmap_entries > 256) | |
2663 cmap_entries = 256; | |
2664 | |
2665 if (cmap_entries > image->colormap_entries) | |
2666 png_error(png_ptr, "palette color-map: too few entries"); | |
2667 | |
2668 for (i=0; i < cmap_entries; ++i) | |
2669 { | |
2670 if (do_background && i < num_trans && trans[i] < 255) | |
2671 { | |
2672 if (trans[i] == 0) | |
2673 png_create_colormap_entry(display, i, back_r, back_g, | |
2674 back_b, 0, output_encoding); | |
2675 | |
2676 else | |
2677 { | |
2678 /* Must compose the PNG file color in the color-map entry | |
2679 * on the sRGB color in 'back'. | |
2680 */ | |
2681 png_create_colormap_entry(display, i, | |
2682 png_colormap_compose(display, colormap[i].red, E_FILE, | |
2683 trans[i], back_r, output_encoding), | |
2684 png_colormap_compose(display, colormap[i].green, E_FILE, | |
2685 trans[i], back_g, output_encoding), | |
2686 png_colormap_compose(display, colormap[i].blue, E_FILE, | |
2687 trans[i], back_b, output_encoding), | |
2688 output_encoding == E_LINEAR ? trans[i] * 257U : | |
2689 trans[i], | |
2690 output_encoding); | |
2691 } | |
2692 } | |
2693 | |
2694 else | |
2695 png_create_colormap_entry(display, i, colormap[i].red, | |
2696 colormap[i].green, colormap[i].blue, | |
2697 i < num_trans ? trans[i] : 255U, E_FILE/*8-bit*/); | |
2698 } | |
2699 | |
2700 /* The PNG data may have indicies packed in fewer than 8 bits, it | |
2701 * must be expanded if so. | |
2702 */ | |
2703 if (png_ptr->bit_depth < 8) | |
2704 png_set_packing(png_ptr); | |
2705 } | |
2706 break; | |
2707 | |
2708 default: | |
2709 png_error(png_ptr, "invalid PNG color type"); | |
2710 /*NOT REACHED*/ | |
2711 break; | |
2712 } | |
2713 | |
2714 /* Now deal with the output processing */ | |
2715 if (expand_tRNS && png_ptr->num_trans > 0 && | |
2716 (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0) | |
2717 png_set_tRNS_to_alpha(png_ptr); | |
2718 | |
2719 switch (data_encoding) | |
2720 { | |
2721 default: | |
2722 png_error(png_ptr, "bad data option (internal error)"); | |
2723 break; | |
2724 | |
2725 case E_sRGB: | |
2726 /* Change to 8-bit sRGB */ | |
2727 png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB); | |
2728 /* FALL THROUGH */ | |
2729 | |
2730 case E_FILE: | |
2731 if (png_ptr->bit_depth > 8) | |
2732 png_set_scale_16(png_ptr); | |
2733 break; | |
2734 } | |
2735 | |
2736 if (cmap_entries > 256 || cmap_entries > image->colormap_entries) | |
2737 png_error(png_ptr, "color map overflow (BAD internal error)"); | |
2738 | |
2739 image->colormap_entries = cmap_entries; | |
2740 | |
2741 /* Double check using the recorded background index */ | |
2742 switch (output_processing) | |
2743 { | |
2744 case PNG_CMAP_NONE: | |
2745 if (background_index != PNG_CMAP_NONE_BACKGROUND) | |
2746 goto bad_background; | |
2747 break; | |
2748 | |
2749 case PNG_CMAP_GA: | |
2750 if (background_index != PNG_CMAP_GA_BACKGROUND) | |
2751 goto bad_background; | |
2752 break; | |
2753 | |
2754 case PNG_CMAP_TRANS: | |
2755 if (background_index >= cmap_entries || | |
2756 background_index != PNG_CMAP_TRANS_BACKGROUND) | |
2757 goto bad_background; | |
2758 break; | |
2759 | |
2760 case PNG_CMAP_RGB: | |
2761 if (background_index != PNG_CMAP_RGB_BACKGROUND) | |
2762 goto bad_background; | |
2763 break; | |
2764 | |
2765 case PNG_CMAP_RGB_ALPHA: | |
2766 if (background_index != PNG_CMAP_RGB_ALPHA_BACKGROUND) | |
2767 goto bad_background; | |
2768 break; | |
2769 | |
2770 default: | |
2771 png_error(png_ptr, "bad processing option (internal error)"); | |
2772 | |
2773 bad_background: | |
2774 png_error(png_ptr, "bad background index (internal error)"); | |
2775 } | |
2776 | |
2777 display->colormap_processing = output_processing; | |
2778 | |
2779 return 1/*ok*/; | |
2780 } | |
2781 | |
2782 /* The final part of the color-map read called from png_image_finish_read. */ | |
2783 static int | |
2784 png_image_read_and_map(png_voidp argument) | |
2785 { | |
2786 png_image_read_control *display = png_voidcast(png_image_read_control*, | |
2787 argument); | |
2788 png_imagep image = display->image; | |
2789 png_structrp png_ptr = image->opaque->png_ptr; | |
2790 int passes; | |
2791 | |
2792 /* Called when the libpng data must be transformed into the color-mapped | |
2793 * form. There is a local row buffer in display->local and this routine must | |
2794 * do the interlace handling. | |
2795 */ | |
2796 switch (png_ptr->interlaced) | |
2797 { | |
2798 case PNG_INTERLACE_NONE: | |
2799 passes = 1; | |
2800 break; | |
2801 | |
2802 case PNG_INTERLACE_ADAM7: | |
2803 passes = PNG_INTERLACE_ADAM7_PASSES; | |
2804 break; | |
2805 | |
2806 default: | |
2807 passes = 0; | |
2808 png_error(png_ptr, "unknown interlace type"); | |
2809 } | |
2810 | |
2811 { | |
2812 png_uint_32 height = image->height; | |
2813 png_uint_32 width = image->width; | |
2814 int proc = display->colormap_processing; | |
2815 png_bytep first_row = png_voidcast(png_bytep, display->first_row); | |
2816 ptrdiff_t step_row = display->row_bytes; | |
2817 int pass; | |
2818 | |
2819 for (pass = 0; pass < passes; ++pass) | |
2820 { | |
2821 unsigned int startx, stepx, stepy; | |
2822 png_uint_32 y; | |
2823 | |
2824 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) | |
2825 { | |
2826 /* The row may be empty for a short image: */ | |
2827 if (PNG_PASS_COLS(width, pass) == 0) | |
2828 continue; | |
2829 | |
2830 startx = PNG_PASS_START_COL(pass); | |
2831 stepx = PNG_PASS_COL_OFFSET(pass); | |
2832 y = PNG_PASS_START_ROW(pass); | |
2833 stepy = PNG_PASS_ROW_OFFSET(pass); | |
2834 } | |
2835 | |
2836 else | |
2837 { | |
2838 y = 0; | |
2839 startx = 0; | |
2840 stepx = stepy = 1; | |
2841 } | |
2842 | |
2843 for (; y<height; y += stepy) | |
2844 { | |
2845 png_bytep inrow = png_voidcast(png_bytep, display->local_row); | |
2846 png_bytep outrow = first_row + y * step_row; | |
2847 png_const_bytep end_row = outrow + width; | |
2848 | |
2849 /* Read read the libpng data into the temporary buffer. */ | |
2850 png_read_row(png_ptr, inrow, NULL); | |
2851 | |
2852 /* Now process the row according to the processing option, note | |
2853 * that the caller verifies that the format of the libpng output | |
2854 * data is as required. | |
2855 */ | |
2856 outrow += startx; | |
2857 switch (proc) | |
2858 { | |
2859 case PNG_CMAP_GA: | |
2860 for (; outrow < end_row; outrow += stepx) | |
2861 { | |
2862 /* The data is always in the PNG order */ | |
2863 unsigned int gray = *inrow++; | |
2864 unsigned int alpha = *inrow++; | |
2865 unsigned int entry; | |
2866 | |
2867 /* NOTE: this code is copied as a comment in | |
2868 * make_ga_colormap above. Please update the | |
2869 * comment if you change this code! | |
2870 */ | |
2871 if (alpha > 229) /* opaque */ | |
2872 { | |
2873 entry = (231 * gray + 128) >> 8; | |
2874 } | |
2875 else if (alpha < 26) /* transparent */ | |
2876 { | |
2877 entry = 231; | |
2878 } | |
2879 else /* partially opaque */ | |
2880 { | |
2881 entry = 226 + 6 * PNG_DIV51(alpha) + PNG_DIV51(gray); | |
2882 } | |
2883 | |
2884 *outrow = (png_byte)entry; | |
2885 } | |
2886 break; | |
2887 | |
2888 case PNG_CMAP_TRANS: | |
2889 for (; outrow < end_row; outrow += stepx) | |
2890 { | |
2891 png_byte gray = *inrow++; | |
2892 png_byte alpha = *inrow++; | |
2893 | |
2894 if (alpha == 0) | |
2895 *outrow = PNG_CMAP_TRANS_BACKGROUND; | |
2896 | |
2897 else if (gray != PNG_CMAP_TRANS_BACKGROUND) | |
2898 *outrow = gray; | |
2899 | |
2900 else | |
2901 *outrow = (png_byte)(PNG_CMAP_TRANS_BACKGROUND+1); | |
2902 } | |
2903 break; | |
2904 | |
2905 case PNG_CMAP_RGB: | |
2906 for (; outrow < end_row; outrow += stepx) | |
2907 { | |
2908 *outrow = PNG_RGB_INDEX(inrow[0], inrow[1], inrow[2]); | |
2909 inrow += 3; | |
2910 } | |
2911 break; | |
2912 | |
2913 case PNG_CMAP_RGB_ALPHA: | |
2914 for (; outrow < end_row; outrow += stepx) | |
2915 { | |
2916 unsigned int alpha = inrow[3]; | |
2917 | |
2918 /* Because the alpha entries only hold alpha==0.5 values | |
2919 * split the processing at alpha==0.25 (64) and 0.75 | |
2920 * (196). | |
2921 */ | |
2922 | |
2923 if (alpha >= 196) | |
2924 *outrow = PNG_RGB_INDEX(inrow[0], inrow[1], | |
2925 inrow[2]); | |
2926 | |
2927 else if (alpha < 64) | |
2928 *outrow = PNG_CMAP_RGB_ALPHA_BACKGROUND; | |
2929 | |
2930 else | |
2931 { | |
2932 /* Likewise there are three entries for each of r, g | |
2933 * and b. We could select the entry by popcount on | |
2934 * the top two bits on those architectures that | |
2935 * support it, this is what the code below does, | |
2936 * crudely. | |
2937 */ | |
2938 unsigned int back_i = PNG_CMAP_RGB_ALPHA_BACKGROUND+1; | |
2939 | |
2940 /* Here are how the values map: | |
2941 * | |
2942 * 0x00 .. 0x3f -> 0 | |
2943 * 0x40 .. 0xbf -> 1 | |
2944 * 0xc0 .. 0xff -> 2 | |
2945 * | |
2946 * So, as above with the explicit alpha checks, the | |
2947 * breakpoints are at 64 and 196. | |
2948 */ | |
2949 if (inrow[0] & 0x80) back_i += 9; /* red */ | |
2950 if (inrow[0] & 0x40) back_i += 9; | |
2951 if (inrow[0] & 0x80) back_i += 3; /* green */ | |
2952 if (inrow[0] & 0x40) back_i += 3; | |
2953 if (inrow[0] & 0x80) back_i += 1; /* blue */ | |
2954 if (inrow[0] & 0x40) back_i += 1; | |
2955 | |
2956 *outrow = (png_byte)back_i; | |
2957 } | |
2958 | |
2959 inrow += 4; | |
2960 } | |
2961 break; | |
2962 | |
2963 default: | |
2964 break; | |
2965 } | |
2966 } | |
2967 } | |
2968 } | |
2969 | |
2970 return 1; | |
2971 } | |
2972 | |
2973 static int | |
2974 png_image_read_colormapped(png_voidp argument) | |
2975 { | |
2976 png_image_read_control *display = png_voidcast(png_image_read_control*, | |
2977 argument); | |
2978 png_imagep image = display->image; | |
2979 png_controlp control = image->opaque; | |
2980 png_structrp png_ptr = control->png_ptr; | |
2981 png_inforp info_ptr = control->info_ptr; | |
2982 | |
2983 int passes = 0; /* As a flag */ | |
2984 | |
2985 PNG_SKIP_CHUNKS(png_ptr); | |
2986 | |
2987 /* Update the 'info' structure and make sure the result is as required; first | |
2988 * make sure to turn on the interlace handling if it will be required | |
2989 * (because it can't be turned on *after* the call to png_read_update_info!) | |
2990 */ | |
2991 if (display->colormap_processing == PNG_CMAP_NONE) | |
2992 passes = png_set_interlace_handling(png_ptr); | |
2993 | |
2994 png_read_update_info(png_ptr, info_ptr); | |
2995 | |
2996 /* The expected output can be deduced from the colormap_processing option. */ | |
2997 switch (display->colormap_processing) | |
2998 { | |
2999 case PNG_CMAP_NONE: | |
3000 /* Output must be one channel and one byte per pixel, the output | |
3001 * encoding can be anything. | |
3002 */ | |
3003 if ((info_ptr->color_type == PNG_COLOR_TYPE_PALETTE || | |
3004 info_ptr->color_type == PNG_COLOR_TYPE_GRAY) && | |
3005 info_ptr->bit_depth == 8) | |
3006 break; | |
3007 | |
3008 goto bad_output; | |
3009 | |
3010 case PNG_CMAP_TRANS: | |
3011 case PNG_CMAP_GA: | |
3012 /* Output must be two channels and the 'G' one must be sRGB, the latter | |
3013 * can be checked with an exact number because it should have been set | |
3014 * to this number above! | |
3015 */ | |
3016 if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA && | |
3017 info_ptr->bit_depth == 8 && | |
3018 png_ptr->screen_gamma == PNG_GAMMA_sRGB && | |
3019 image->colormap_entries == 256) | |
3020 break; | |
3021 | |
3022 goto bad_output; | |
3023 | |
3024 case PNG_CMAP_RGB: | |
3025 /* Output must be 8-bit sRGB encoded RGB */ | |
3026 if (info_ptr->color_type == PNG_COLOR_TYPE_RGB && | |
3027 info_ptr->bit_depth == 8 && | |
3028 png_ptr->screen_gamma == PNG_GAMMA_sRGB && | |
3029 image->colormap_entries == 216) | |
3030 break; | |
3031 | |
3032 goto bad_output; | |
3033 | |
3034 case PNG_CMAP_RGB_ALPHA: | |
3035 /* Output must be 8-bit sRGB encoded RGBA */ | |
3036 if (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA && | |
3037 info_ptr->bit_depth == 8 && | |
3038 png_ptr->screen_gamma == PNG_GAMMA_sRGB && | |
3039 image->colormap_entries == 244 /* 216 + 1 + 27 */) | |
3040 break; | |
3041 | |
3042 /* goto bad_output; */ | |
3043 /* FALL THROUGH */ | |
3044 | |
3045 default: | |
3046 bad_output: | |
3047 png_error(png_ptr, "bad color-map processing (internal error)"); | |
3048 } | |
3049 | |
3050 /* Now read the rows. Do this here if it is possible to read directly into | |
3051 * the output buffer, otherwise allocate a local row buffer of the maximum | |
3052 * size libpng requires and call the relevant processing routine safely. | |
3053 */ | |
3054 { | |
3055 png_voidp first_row = display->buffer; | |
3056 ptrdiff_t row_bytes = display->row_stride; | |
3057 | |
3058 /* The following expression is designed to work correctly whether it gives | |
3059 * a signed or an unsigned result. | |
3060 */ | |
3061 if (row_bytes < 0) | |
3062 { | |
3063 char *ptr = png_voidcast(char*, first_row); | |
3064 ptr += (image->height-1) * (-row_bytes); | |
3065 first_row = png_voidcast(png_voidp, ptr); | |
3066 } | |
3067 | |
3068 display->first_row = first_row; | |
3069 display->row_bytes = row_bytes; | |
3070 } | |
3071 | |
3072 if (passes == 0) | |
3073 { | |
3074 int result; | |
3075 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr)); | |
3076 | |
3077 display->local_row = row; | |
3078 result = png_safe_execute(image, png_image_read_and_map, display); | |
3079 display->local_row = NULL; | |
3080 png_free(png_ptr, row); | |
3081 | |
3082 return result; | |
3083 } | |
3084 | |
3085 else | |
3086 { | |
3087 png_alloc_size_t row_bytes = display->row_bytes; | |
3088 | |
3089 while (--passes >= 0) | |
3090 { | |
3091 png_uint_32 y = image->height; | |
3092 png_bytep row = png_voidcast(png_bytep, display->first_row); | |
3093 | |
3094 while (y-- > 0) | |
3095 { | |
3096 png_read_row(png_ptr, row, NULL); | |
3097 row += row_bytes; | |
3098 } | |
3099 } | |
3100 | |
3101 return 1; | |
3102 } | |
3103 } | |
3104 | |
3105 /* Just the row reading part of png_image_read. */ | |
3106 static int | |
3107 png_image_read_composite(png_voidp argument) | |
3108 { | |
3109 png_image_read_control *display = png_voidcast(png_image_read_control*, | |
3110 argument); | |
3111 png_imagep image = display->image; | |
3112 png_structrp png_ptr = image->opaque->png_ptr; | |
3113 int passes; | |
3114 | |
3115 switch (png_ptr->interlaced) | |
3116 { | |
3117 case PNG_INTERLACE_NONE: | |
3118 passes = 1; | |
3119 break; | |
3120 | |
3121 case PNG_INTERLACE_ADAM7: | |
3122 passes = PNG_INTERLACE_ADAM7_PASSES; | |
3123 break; | |
3124 | |
3125 default: | |
3126 passes = 0; | |
3127 png_error(png_ptr, "unknown interlace type"); | |
3128 } | |
3129 | |
3130 { | |
3131 png_uint_32 height = image->height; | |
3132 png_uint_32 width = image->width; | |
3133 ptrdiff_t step_row = display->row_bytes; | |
3134 unsigned int channels = (image->format & PNG_FORMAT_FLAG_COLOR) ? 3 : 1; | |
3135 int pass; | |
3136 | |
3137 for (pass = 0; pass < passes; ++pass) | |
3138 { | |
3139 unsigned int startx, stepx, stepy; | |
3140 png_uint_32 y; | |
3141 | |
3142 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) | |
3143 { | |
3144 /* The row may be empty for a short image: */ | |
3145 if (PNG_PASS_COLS(width, pass) == 0) | |
3146 continue; | |
3147 | |
3148 startx = PNG_PASS_START_COL(pass) * channels; | |
3149 stepx = PNG_PASS_COL_OFFSET(pass) * channels; | |
3150 y = PNG_PASS_START_ROW(pass); | |
3151 stepy = PNG_PASS_ROW_OFFSET(pass); | |
3152 } | |
3153 | |
3154 else | |
3155 { | |
3156 y = 0; | |
3157 startx = 0; | |
3158 stepx = channels; | |
3159 stepy = 1; | |
3160 } | |
3161 | |
3162 for (; y<height; y += stepy) | |
3163 { | |
3164 png_bytep inrow = png_voidcast(png_bytep, display->local_row); | |
3165 png_bytep outrow; | |
3166 png_const_bytep end_row; | |
3167 | |
3168 /* Read the row, which is packed: */ | |
3169 png_read_row(png_ptr, inrow, NULL); | |
3170 | |
3171 outrow = png_voidcast(png_bytep, display->first_row); | |
3172 outrow += y * step_row; | |
3173 end_row = outrow + width * channels; | |
3174 | |
3175 /* Now do the composition on each pixel in this row. */ | |
3176 outrow += startx; | |
3177 for (; outrow < end_row; outrow += stepx) | |
3178 { | |
3179 png_byte alpha = inrow[channels]; | |
3180 | |
3181 if (alpha > 0) /* else no change to the output */ | |
3182 { | |
3183 unsigned int c; | |
3184 | |
3185 for (c=0; c<channels; ++c) | |
3186 { | |
3187 png_uint_32 component = inrow[c]; | |
3188 | |
3189 if (alpha < 255) /* else just use component */ | |
3190 { | |
3191 /* This is PNG_OPTIMIZED_ALPHA, the component value | |
3192 * is a linear 8-bit value. Combine this with the | |
3193 * current outrow[c] value which is sRGB encoded. | |
3194 * Arithmetic here is 16-bits to preserve the output | |
3195 * values correctly. | |
3196 */ | |
3197 component *= 257*255; /* =65535 */ | |
3198 component += (255-alpha)*png_sRGB_table[outrow[c]]; | |
3199 | |
3200 /* So 'component' is scaled by 255*65535 and is | |
3201 * therefore appropriate for the sRGB to linear | |
3202 * conversion table. | |
3203 */ | |
3204 component = PNG_sRGB_FROM_LINEAR(component); | |
3205 } | |
3206 | |
3207 outrow[c] = (png_byte)component; | |
3208 } | |
3209 } | |
3210 | |
3211 inrow += channels+1; /* components and alpha channel */ | |
3212 } | |
3213 } | |
3214 } | |
3215 } | |
3216 | |
3217 return 1; | |
3218 } | |
3219 | |
3220 /* The do_local_background case; called when all the following transforms are to | |
3221 * be done: | |
3222 * | |
3223 * PNG_RGB_TO_GRAY | |
3224 * PNG_COMPOSITE | |
3225 * PNG_GAMMA | |
3226 * | |
3227 * This is a work-round for the fact that both the PNG_RGB_TO_GRAY and | |
3228 * PNG_COMPOSITE code performs gamma correction, so we get double gamma | |
3229 * correction. The fix-up is to prevent the PNG_COMPOSITE operation happening | |
3230 * inside libpng, so this routine sees an 8 or 16-bit gray+alpha row and handles | |
3231 * the removal or pre-multiplication of the alpha channel. | |
3232 */ | |
3233 static int | |
3234 png_image_read_background(png_voidp argument) | |
3235 { | |
3236 png_image_read_control *display = png_voidcast(png_image_read_control*, | |
3237 argument); | |
3238 png_imagep image = display->image; | |
3239 png_structrp png_ptr = image->opaque->png_ptr; | |
3240 png_inforp info_ptr = image->opaque->info_ptr; | |
3241 png_uint_32 height = image->height; | |
3242 png_uint_32 width = image->width; | |
3243 int pass, passes; | |
3244 | |
3245 /* Double check the convoluted logic below. We expect to get here with | |
3246 * libpng doing rgb to gray and gamma correction but background processing | |
3247 * left to the png_image_read_background function. The rows libpng produce | |
3248 * might be 8 or 16-bit but should always have two channels; gray plus alpha. | |
3249 */ | |
3250 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 0) | |
3251 png_error(png_ptr, "lost rgb to gray"); | |
3252 | |
3253 if ((png_ptr->transformations & PNG_COMPOSE) != 0) | |
3254 png_error(png_ptr, "unexpected compose"); | |
3255 | |
3256 if (png_get_channels(png_ptr, info_ptr) != 2) | |
3257 png_error(png_ptr, "lost/gained channels"); | |
3258 | |
3259 /* Expect the 8-bit case to always remove the alpha channel */ | |
3260 if ((image->format & PNG_FORMAT_FLAG_LINEAR) == 0 && | |
3261 (image->format & PNG_FORMAT_FLAG_ALPHA) != 0) | |
3262 png_error(png_ptr, "unexpected 8-bit transformation"); | |
3263 | |
3264 switch (png_ptr->interlaced) | |
3265 { | |
3266 case PNG_INTERLACE_NONE: | |
3267 passes = 1; | |
3268 break; | |
3269 | |
3270 case PNG_INTERLACE_ADAM7: | |
3271 passes = PNG_INTERLACE_ADAM7_PASSES; | |
3272 break; | |
3273 | |
3274 default: | |
3275 passes = 0; | |
3276 png_error(png_ptr, "unknown interlace type"); | |
3277 } | |
3278 | |
3279 switch (png_get_bit_depth(png_ptr, info_ptr)) | |
3280 { | |
3281 default: | |
3282 png_error(png_ptr, "unexpected bit depth"); | |
3283 break; | |
3284 | |
3285 case 8: | |
3286 /* 8-bit sRGB gray values with an alpha channel; the alpha channel is | |
3287 * to be removed by composing on a backgroundi: either the row if | |
3288 * display->background is NULL or display->background->green if not. | |
3289 * Unlike the code above ALPHA_OPTIMIZED has *not* been done. | |
3290 */ | |
3291 { | |
3292 png_bytep first_row = png_voidcast(png_bytep, display->first_row); | |
3293 ptrdiff_t step_row = display->row_bytes; | |
3294 | |
3295 for (pass = 0; pass < passes; ++pass) | |
3296 { | |
3297 png_bytep row = png_voidcast(png_bytep, | |
3298 display->first_row); | |
3299 unsigned int startx, stepx, stepy; | |
3300 png_uint_32 y; | |
3301 | |
3302 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) | |
3303 { | |
3304 /* The row may be empty for a short image: */ | |
3305 if (PNG_PASS_COLS(width, pass) == 0) | |
3306 continue; | |
3307 | |
3308 startx = PNG_PASS_START_COL(pass); | |
3309 stepx = PNG_PASS_COL_OFFSET(pass); | |
3310 y = PNG_PASS_START_ROW(pass); | |
3311 stepy = PNG_PASS_ROW_OFFSET(pass); | |
3312 } | |
3313 | |
3314 else | |
3315 { | |
3316 y = 0; | |
3317 startx = 0; | |
3318 stepx = stepy = 1; | |
3319 } | |
3320 | |
3321 if (display->background == NULL) | |
3322 { | |
3323 for (; y<height; y += stepy) | |
3324 { | |
3325 png_bytep inrow = png_voidcast(png_bytep, | |
3326 display->local_row); | |
3327 png_bytep outrow = first_row + y * step_row; | |
3328 png_const_bytep end_row = outrow + width; | |
3329 | |
3330 /* Read the row, which is packed: */ | |
3331 png_read_row(png_ptr, inrow, NULL); | |
3332 | |
3333 /* Now do the composition on each pixel in this row. */ | |
3334 outrow += startx; | |
3335 for (; outrow < end_row; outrow += stepx) | |
3336 { | |
3337 png_byte alpha = inrow[1]; | |
3338 | |
3339 if (alpha > 0) /* else no change to the output */ | |
3340 { | |
3341 png_uint_32 component = inrow[0]; | |
3342 | |
3343 if (alpha < 255) /* else just use component */ | |
3344 { | |
3345 /* Since PNG_OPTIMIZED_ALPHA was not set it is | |
3346 * necessary to invert the sRGB transfer | |
3347 * function and multiply the alpha out. | |
3348 */ | |
3349 component = png_sRGB_table[component] * alpha; | |
3350 component += png_sRGB_table[outrow[0]] * | |
3351 (255-alpha); | |
3352 component = PNG_sRGB_FROM_LINEAR(component); | |
3353 } | |
3354 | |
3355 outrow[0] = (png_byte)component; | |
3356 } | |
3357 | |
3358 inrow += 2; /* gray and alpha channel */ | |
3359 } | |
3360 } | |
3361 } | |
3362 | |
3363 else /* constant background value */ | |
3364 { | |
3365 png_byte background8 = display->background->green; | |
3366 png_uint_16 background = png_sRGB_table[background8]; | |
3367 | |
3368 for (; y<height; y += stepy) | |
3369 { | |
3370 png_bytep inrow = png_voidcast(png_bytep, | |
3371 display->local_row); | |
3372 png_bytep outrow = first_row + y * step_row; | |
3373 png_const_bytep end_row = outrow + width; | |
3374 | |
3375 /* Read the row, which is packed: */ | |
3376 png_read_row(png_ptr, inrow, NULL); | |
3377 | |
3378 /* Now do the composition on each pixel in this row. */ | |
3379 outrow += startx; | |
3380 for (; outrow < end_row; outrow += stepx) | |
3381 { | |
3382 png_byte alpha = inrow[1]; | |
3383 | |
3384 if (alpha > 0) /* else use background */ | |
3385 { | |
3386 png_uint_32 component = inrow[0]; | |
3387 | |
3388 if (alpha < 255) /* else just use component */ | |
3389 { | |
3390 component = png_sRGB_table[component] * alpha; | |
3391 component += background * (255-alpha); | |
3392 component = PNG_sRGB_FROM_LINEAR(component); | |
3393 } | |
3394 | |
3395 outrow[0] = (png_byte)component; | |
3396 } | |
3397 | |
3398 else | |
3399 outrow[0] = background8; | |
3400 | |
3401 inrow += 2; /* gray and alpha channel */ | |
3402 } | |
3403 | |
3404 row += display->row_bytes; | |
3405 } | |
3406 } | |
3407 } | |
3408 } | |
3409 break; | |
3410 | |
3411 case 16: | |
3412 /* 16-bit linear with pre-multiplied alpha; the pre-multiplication must | |
3413 * still be done and, maybe, the alpha channel removed. This code also | |
3414 * handles the alpha-first option. | |
3415 */ | |
3416 { | |
3417 png_uint_16p first_row = png_voidcast(png_uint_16p, | |
3418 display->first_row); | |
3419 /* The division by two is safe because the caller passed in a | |
3420 * stride which was multiplied by 2 (below) to get row_bytes. | |
3421 */ | |
3422 ptrdiff_t step_row = display->row_bytes / 2; | |
3423 int preserve_alpha = (image->format & PNG_FORMAT_FLAG_ALPHA) != 0; | |
3424 unsigned int outchannels = 1+preserve_alpha; | |
3425 int swap_alpha = 0; | |
3426 | |
3427 if (preserve_alpha && (image->format & PNG_FORMAT_FLAG_AFIRST)) | |
3428 swap_alpha = 1; | |
3429 | |
3430 for (pass = 0; pass < passes; ++pass) | |
3431 { | |
3432 unsigned int startx, stepx, stepy; | |
3433 png_uint_32 y; | |
3434 | |
3435 /* The 'x' start and step are adjusted to output components here. | |
3436 */ | |
3437 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) | |
3438 { | |
3439 /* The row may be empty for a short image: */ | |
3440 if (PNG_PASS_COLS(width, pass) == 0) | |
3441 continue; | |
3442 | |
3443 startx = PNG_PASS_START_COL(pass) * outchannels; | |
3444 stepx = PNG_PASS_COL_OFFSET(pass) * outchannels; | |
3445 y = PNG_PASS_START_ROW(pass); | |
3446 stepy = PNG_PASS_ROW_OFFSET(pass); | |
3447 } | |
3448 | |
3449 else | |
3450 { | |
3451 y = 0; | |
3452 startx = 0; | |
3453 stepx = outchannels; | |
3454 stepy = 1; | |
3455 } | |
3456 | |
3457 for (; y<height; y += stepy) | |
3458 { | |
3459 png_const_uint_16p inrow; | |
3460 png_uint_16p outrow = first_row + y*step_row; | |
3461 png_uint_16p end_row = outrow + width * outchannels; | |
3462 | |
3463 /* Read the row, which is packed: */ | |
3464 png_read_row(png_ptr, png_voidcast(png_bytep, | |
3465 display->local_row), NULL); | |
3466 inrow = png_voidcast(png_const_uint_16p, display->local_row); | |
3467 | |
3468 /* Now do the pre-multiplication on each pixel in this row. | |
3469 */ | |
3470 outrow += startx; | |
3471 for (; outrow < end_row; outrow += stepx) | |
3472 { | |
3473 png_uint_32 component = inrow[0]; | |
3474 png_uint_16 alpha = inrow[1]; | |
3475 | |
3476 if (alpha > 0) /* else 0 */ | |
3477 { | |
3478 if (alpha < 65535) /* else just use component */ | |
3479 { | |
3480 component *= alpha; | |
3481 component += 32767; | |
3482 component /= 65535; | |
3483 } | |
3484 } | |
3485 | |
3486 else | |
3487 component = 0; | |
3488 | |
3489 outrow[swap_alpha] = (png_uint_16)component; | |
3490 if (preserve_alpha) | |
3491 outrow[1 ^ swap_alpha] = alpha; | |
3492 | |
3493 inrow += 2; /* components and alpha channel */ | |
3494 } | |
3495 } | |
3496 } | |
3497 } | |
3498 break; | |
3499 } | |
3500 | |
3501 return 1; | |
3502 } | |
3503 | |
3504 /* The guts of png_image_finish_read as a png_safe_execute callback. */ | |
3505 static int | |
3506 png_image_read_direct(png_voidp argument) | |
3507 { | |
3508 png_image_read_control *display = png_voidcast(png_image_read_control*, | |
3509 argument); | |
3510 png_imagep image = display->image; | |
3511 png_structrp png_ptr = image->opaque->png_ptr; | |
3512 png_inforp info_ptr = image->opaque->info_ptr; | |
3513 | |
3514 png_uint_32 format = image->format; | |
3515 int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0; | |
3516 int do_local_compose = 0; | |
3517 int do_local_background = 0; /* to avoid double gamma correction bug */ | |
3518 int passes = 0; | |
3519 | |
3520 /* Add transforms to ensure the correct output format is produced then check | |
3521 * that the required implementation support is there. Always expand; always | |
3522 * need 8 bits minimum, no palette and expanded tRNS. | |
3523 */ | |
3524 png_set_expand(png_ptr); | |
3525 | |
3526 /* Now check the format to see if it was modified. */ | |
3527 { | |
3528 png_uint_32 base_format = png_image_format(png_ptr) & | |
3529 ~PNG_FORMAT_FLAG_COLORMAP /* removed by png_set_expand */; | |
3530 png_uint_32 change = format ^ base_format; | |
3531 png_fixed_point output_gamma; | |
3532 int mode; /* alpha mode */ | |
3533 | |
3534 /* Do this first so that we have a record if rgb to gray is happening. */ | |
3535 if (change & PNG_FORMAT_FLAG_COLOR) | |
3536 { | |
3537 /* gray<->color transformation required. */ | |
3538 if (format & PNG_FORMAT_FLAG_COLOR) | |
3539 png_set_gray_to_rgb(png_ptr); | |
3540 | |
3541 else | |
3542 { | |
3543 /* libpng can't do both rgb to gray and | |
3544 * background/pre-multiplication if there is also significant gamma | |
3545 * correction, because both operations require linear colors and | |
3546 * the code only supports one transform doing the gamma correction. | |
3547 * Handle this by doing the pre-multiplication or background | |
3548 * operation in this code, if necessary. | |
3549 * | |
3550 * TODO: fix this by rewriting pngrtran.c (!) | |
3551 * | |
3552 * For the moment (given that fixing this in pngrtran.c is an | |
3553 * enormous change) 'do_local_background' is used to indicate that | |
3554 * the problem exists. | |
3555 */ | |
3556 if (base_format & PNG_FORMAT_FLAG_ALPHA) | |
3557 do_local_background = 1/*maybe*/; | |
3558 | |
3559 png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, | |
3560 PNG_RGB_TO_GRAY_DEFAULT, PNG_RGB_TO_GRAY_DEFAULT); | |
3561 } | |
3562 | |
3563 change &= ~PNG_FORMAT_FLAG_COLOR; | |
3564 } | |
3565 | |
3566 /* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise. | |
3567 */ | |
3568 { | |
3569 png_fixed_point input_gamma_default; | |
3570 | |
3571 if ((base_format & PNG_FORMAT_FLAG_LINEAR) && | |
3572 (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0) | |
3573 input_gamma_default = PNG_GAMMA_LINEAR; | |
3574 else | |
3575 input_gamma_default = PNG_DEFAULT_sRGB; | |
3576 | |
3577 /* Call png_set_alpha_mode to set the default for the input gamma; the | |
3578 * output gamma is set by a second call below. | |
3579 */ | |
3580 png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, input_gamma_default); | |
3581 } | |
3582 | |
3583 if (linear) | |
3584 { | |
3585 /* If there *is* an alpha channel in the input it must be multiplied | |
3586 * out; use PNG_ALPHA_STANDARD, otherwise just use PNG_ALPHA_PNG. | |
3587 */ | |
3588 if (base_format & PNG_FORMAT_FLAG_ALPHA) | |
3589 mode = PNG_ALPHA_STANDARD; /* associated alpha */ | |
3590 | |
3591 else | |
3592 mode = PNG_ALPHA_PNG; | |
3593 | |
3594 output_gamma = PNG_GAMMA_LINEAR; | |
3595 } | |
3596 | |
3597 else | |
3598 { | |
3599 mode = PNG_ALPHA_PNG; | |
3600 output_gamma = PNG_DEFAULT_sRGB; | |
3601 } | |
3602 | |
3603 /* If 'do_local_background' is set check for the presence of gamma | |
3604 * correction; this is part of the work-round for the libpng bug | |
3605 * described above. | |
3606 * | |
3607 * TODO: fix libpng and remove this. | |
3608 */ | |
3609 if (do_local_background) | |
3610 { | |
3611 png_fixed_point gtest; | |
3612 | |
3613 /* This is 'png_gamma_threshold' from pngrtran.c; the test used for | |
3614 * gamma correction, the screen gamma hasn't been set on png_struct | |
3615 * yet; it's set below. png_struct::gamma, however, is set to the | |
3616 * final value. | |
3617 */ | |
3618 if (png_muldiv(>est, output_gamma, png_ptr->colorspace.gamma, | |
3619 PNG_FP_1) && !png_gamma_significant(gtest)) | |
3620 do_local_background = 0; | |
3621 | |
3622 else if (mode == PNG_ALPHA_STANDARD) | |
3623 { | |
3624 do_local_background = 2/*required*/; | |
3625 mode = PNG_ALPHA_PNG; /* prevent libpng doing it */ | |
3626 } | |
3627 | |
3628 /* else leave as 1 for the checks below */ | |
3629 } | |
3630 | |
3631 /* If the bit-depth changes then handle that here. */ | |
3632 if (change & PNG_FORMAT_FLAG_LINEAR) | |
3633 { | |
3634 if (linear /*16-bit output*/) | |
3635 png_set_expand_16(png_ptr); | |
3636 | |
3637 else /* 8-bit output */ | |
3638 png_set_scale_16(png_ptr); | |
3639 | |
3640 change &= ~PNG_FORMAT_FLAG_LINEAR; | |
3641 } | |
3642 | |
3643 /* Now the background/alpha channel changes. */ | |
3644 if (change & PNG_FORMAT_FLAG_ALPHA) | |
3645 { | |
3646 /* Removing an alpha channel requires composition for the 8-bit | |
3647 * formats; for the 16-bit it is already done, above, by the | |
3648 * pre-multiplication and the channel just needs to be stripped. | |
3649 */ | |
3650 if (base_format & PNG_FORMAT_FLAG_ALPHA) | |
3651 { | |
3652 /* If RGB->gray is happening the alpha channel must be left and the | |
3653 * operation completed locally. | |
3654 * | |
3655 * TODO: fix libpng and remove this. | |
3656 */ | |
3657 if (do_local_background) | |
3658 do_local_background = 2/*required*/; | |
3659 | |
3660 /* 16-bit output: just remove the channel */ | |
3661 else if (linear) /* compose on black (well, pre-multiply) */ | |
3662 png_set_strip_alpha(png_ptr); | |
3663 | |
3664 /* 8-bit output: do an appropriate compose */ | |
3665 else if (display->background != NULL) | |
3666 { | |
3667 png_color_16 c; | |
3668 | |
3669 c.index = 0; /*unused*/ | |
3670 c.red = display->background->red; | |
3671 c.green = display->background->green; | |
3672 c.blue = display->background->blue; | |
3673 c.gray = display->background->green; | |
3674 | |
3675 /* This is always an 8-bit sRGB value, using the 'green' channel | |
3676 * for gray is much better than calculating the luminance here; | |
3677 * we can get off-by-one errors in that calculation relative to | |
3678 * the app expectations and that will show up in transparent | |
3679 * pixels. | |
3680 */ | |
3681 png_set_background_fixed(png_ptr, &c, | |
3682 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, | |
3683 0/*gamma: not used*/); | |
3684 } | |
3685 | |
3686 else /* compose on row: implemented below. */ | |
3687 { | |
3688 do_local_compose = 1; | |
3689 /* This leaves the alpha channel in the output, so it has to be | |
3690 * removed by the code below. Set the encoding to the 'OPTIMIZE' | |
3691 * one so the code only has to hack on the pixels that require | |
3692 * composition. | |
3693 */ | |
3694 mode = PNG_ALPHA_OPTIMIZED; | |
3695 } | |
3696 } | |
3697 | |
3698 else /* output needs an alpha channel */ | |
3699 { | |
3700 /* This is tricky because it happens before the swap operation has | |
3701 * been accomplished; however, the swap does *not* swap the added | |
3702 * alpha channel (weird API), so it must be added in the correct | |
3703 * place. | |
3704 */ | |
3705 png_uint_32 filler; /* opaque filler */ | |
3706 int where; | |
3707 | |
3708 if (linear) | |
3709 filler = 65535; | |
3710 | |
3711 else | |
3712 filler = 255; | |
3713 | |
3714 # ifdef PNG_FORMAT_AFIRST_SUPPORTED | |
3715 if (format & PNG_FORMAT_FLAG_AFIRST) | |
3716 { | |
3717 where = PNG_FILLER_BEFORE; | |
3718 change &= ~PNG_FORMAT_FLAG_AFIRST; | |
3719 } | |
3720 | |
3721 else | |
3722 # endif | |
3723 where = PNG_FILLER_AFTER; | |
3724 | |
3725 png_set_add_alpha(png_ptr, filler, where); | |
3726 } | |
3727 | |
3728 /* This stops the (irrelevant) call to swap_alpha below. */ | |
3729 change &= ~PNG_FORMAT_FLAG_ALPHA; | |
3730 } | |
3731 | |
3732 /* Now set the alpha mode correctly; this is always done, even if there is | |
3733 * no alpha channel in either the input or the output because it correctly | |
3734 * sets the output gamma. | |
3735 */ | |
3736 png_set_alpha_mode_fixed(png_ptr, mode, output_gamma); | |
3737 | |
3738 # ifdef PNG_FORMAT_BGR_SUPPORTED | |
3739 if (change & PNG_FORMAT_FLAG_BGR) | |
3740 { | |
3741 /* Check only the output format; PNG is never BGR; don't do this if | |
3742 * the output is gray, but fix up the 'format' value in that case. | |
3743 */ | |
3744 if (format & PNG_FORMAT_FLAG_COLOR) | |
3745 png_set_bgr(png_ptr); | |
3746 | |
3747 else | |
3748 format &= ~PNG_FORMAT_FLAG_BGR; | |
3749 | |
3750 change &= ~PNG_FORMAT_FLAG_BGR; | |
3751 } | |
3752 # endif | |
3753 | |
3754 # ifdef PNG_FORMAT_AFIRST_SUPPORTED | |
3755 if (change & PNG_FORMAT_FLAG_AFIRST) | |
3756 { | |
3757 /* Only relevant if there is an alpha channel - it's particularly | |
3758 * important to handle this correctly because do_local_compose may | |
3759 * be set above and then libpng will keep the alpha channel for this | |
3760 * code to remove. | |
3761 */ | |
3762 if (format & PNG_FORMAT_FLAG_ALPHA) | |
3763 { | |
3764 /* Disable this if doing a local background, | |
3765 * TODO: remove this when local background is no longer required. | |
3766 */ | |
3767 if (do_local_background != 2) | |
3768 png_set_swap_alpha(png_ptr); | |
3769 } | |
3770 | |
3771 else | |
3772 format &= ~PNG_FORMAT_FLAG_AFIRST; | |
3773 | |
3774 change &= ~PNG_FORMAT_FLAG_AFIRST; | |
3775 } | |
3776 # endif | |
3777 | |
3778 /* If the *output* is 16-bit then we need to check for a byte-swap on this | |
3779 * architecture. | |
3780 */ | |
3781 if (linear) | |
3782 { | |
3783 PNG_CONST png_uint_16 le = 0x0001; | |
3784 | |
3785 if (*(png_const_bytep)&le) | |
3786 png_set_swap(png_ptr); | |
3787 } | |
3788 | |
3789 /* If change is not now 0 some transformation is missing - error out. */ | |
3790 if (change) | |
3791 png_error(png_ptr, "png_read_image: unsupported transformation"); | |
3792 } | |
3793 | |
3794 PNG_SKIP_CHUNKS(png_ptr); | |
3795 | |
3796 /* Update the 'info' structure and make sure the result is as required; first | |
3797 * make sure to turn on the interlace handling if it will be required | |
3798 * (because it can't be turned on *after* the call to png_read_update_info!) | |
3799 * | |
3800 * TODO: remove the do_local_background fixup below. | |
3801 */ | |
3802 if (!do_local_compose && do_local_background != 2) | |
3803 passes = png_set_interlace_handling(png_ptr); | |
3804 | |
3805 png_read_update_info(png_ptr, info_ptr); | |
3806 | |
3807 { | |
3808 png_uint_32 info_format = 0; | |
3809 | |
3810 if (info_ptr->color_type & PNG_COLOR_MASK_COLOR) | |
3811 info_format |= PNG_FORMAT_FLAG_COLOR; | |
3812 | |
3813 if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA) | |
3814 { | |
3815 /* do_local_compose removes this channel below. */ | |
3816 if (!do_local_compose) | |
3817 { | |
3818 /* do_local_background does the same if required. */ | |
3819 if (do_local_background != 2 || | |
3820 (format & PNG_FORMAT_FLAG_ALPHA) != 0) | |
3821 info_format |= PNG_FORMAT_FLAG_ALPHA; | |
3822 } | |
3823 } | |
3824 | |
3825 else if (do_local_compose) /* internal error */ | |
3826 png_error(png_ptr, "png_image_read: alpha channel lost"); | |
3827 | |
3828 if (info_ptr->bit_depth == 16) | |
3829 info_format |= PNG_FORMAT_FLAG_LINEAR; | |
3830 | |
3831 # ifdef PNG_FORMAT_BGR_SUPPORTED | |
3832 if (png_ptr->transformations & PNG_BGR) | |
3833 info_format |= PNG_FORMAT_FLAG_BGR; | |
3834 # endif | |
3835 | |
3836 # ifdef PNG_FORMAT_AFIRST_SUPPORTED | |
3837 if (do_local_background == 2) | |
3838 { | |
3839 if (format & PNG_FORMAT_FLAG_AFIRST) | |
3840 info_format |= PNG_FORMAT_FLAG_AFIRST; | |
3841 } | |
3842 | |
3843 if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0 || | |
3844 ((png_ptr->transformations & PNG_ADD_ALPHA) != 0 && | |
3845 (png_ptr->flags & PNG_FLAG_FILLER_AFTER) == 0)) | |
3846 { | |
3847 if (do_local_background == 2) | |
3848 png_error(png_ptr, "unexpected alpha swap transformation"); | |
3849 | |
3850 info_format |= PNG_FORMAT_FLAG_AFIRST; | |
3851 } | |
3852 # endif | |
3853 | |
3854 /* This is actually an internal error. */ | |
3855 if (info_format != format) | |
3856 png_error(png_ptr, "png_read_image: invalid transformations"); | |
3857 } | |
3858 | |
3859 /* Now read the rows. If do_local_compose is set then it is necessary to use | |
3860 * a local row buffer. The output will be GA, RGBA or BGRA and must be | |
3861 * converted to G, RGB or BGR as appropriate. The 'local_row' member of the | |
3862 * display acts as a flag. | |
3863 */ | |
3864 { | |
3865 png_voidp first_row = display->buffer; | |
3866 ptrdiff_t row_bytes = display->row_stride; | |
3867 | |
3868 if (linear) | |
3869 row_bytes *= 2; | |
3870 | |
3871 /* The following expression is designed to work correctly whether it gives | |
3872 * a signed or an unsigned result. | |
3873 */ | |
3874 if (row_bytes < 0) | |
3875 { | |
3876 char *ptr = png_voidcast(char*, first_row); | |
3877 ptr += (image->height-1) * (-row_bytes); | |
3878 first_row = png_voidcast(png_voidp, ptr); | |
3879 } | |
3880 | |
3881 display->first_row = first_row; | |
3882 display->row_bytes = row_bytes; | |
3883 } | |
3884 | |
3885 if (do_local_compose) | |
3886 { | |
3887 int result; | |
3888 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr)); | |
3889 | |
3890 display->local_row = row; | |
3891 result = png_safe_execute(image, png_image_read_composite, display); | |
3892 display->local_row = NULL; | |
3893 png_free(png_ptr, row); | |
3894 | |
3895 return result; | |
3896 } | |
3897 | |
3898 else if (do_local_background == 2) | |
3899 { | |
3900 int result; | |
3901 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr)); | |
3902 | |
3903 display->local_row = row; | |
3904 result = png_safe_execute(image, png_image_read_background, display); | |
3905 display->local_row = NULL; | |
3906 png_free(png_ptr, row); | |
3907 | |
3908 return result; | |
3909 } | |
3910 | |
3911 else | |
3912 { | |
3913 png_alloc_size_t row_bytes = display->row_bytes; | |
3914 | |
3915 while (--passes >= 0) | |
3916 { | |
3917 png_uint_32 y = image->height; | |
3918 png_bytep row = png_voidcast(png_bytep, display->first_row); | |
3919 | |
3920 while (y-- > 0) | |
3921 { | |
3922 png_read_row(png_ptr, row, NULL); | |
3923 row += row_bytes; | |
3924 } | |
3925 } | |
3926 | |
3927 return 1; | |
3928 } | |
3929 } | |
3930 | |
3931 int PNGAPI | |
3932 png_image_finish_read(png_imagep image, png_const_colorp background, | |
3933 void *buffer, png_int_32 row_stride, void *colormap) | |
3934 { | |
3935 if (image != NULL && image->version == PNG_IMAGE_VERSION) | |
3936 { | |
3937 png_uint_32 check; | |
3938 | |
3939 if (row_stride == 0) | |
3940 row_stride = PNG_IMAGE_ROW_STRIDE(*image); | |
3941 | |
3942 if (row_stride < 0) | |
3943 check = -row_stride; | |
3944 | |
3945 else | |
3946 check = row_stride; | |
3947 | |
3948 if (image->opaque != NULL && buffer != NULL && | |
3949 check >= PNG_IMAGE_ROW_STRIDE(*image)) | |
3950 { | |
3951 if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 || | |
3952 (image->colormap_entries > 0 && colormap != NULL)) | |
3953 { | |
3954 int result; | |
3955 png_image_read_control display; | |
3956 | |
3957 memset(&display, 0, (sizeof display)); | |
3958 display.image = image; | |
3959 display.buffer = buffer; | |
3960 display.row_stride = row_stride; | |
3961 display.colormap = colormap; | |
3962 display.background = background; | |
3963 display.local_row = NULL; | |
3964 | |
3965 /* Choose the correct 'end' routine; for the color-map case all the | |
3966 * setup has already been done. | |
3967 */ | |
3968 if (image->format & PNG_FORMAT_FLAG_COLORMAP) | |
3969 result = | |
3970 png_safe_execute(image, png_image_read_colormap, &display) && | |
3971 png_safe_execute(image, png_image_read_colormapped, &display); | |
3972 | |
3973 else | |
3974 result = | |
3975 png_safe_execute(image, png_image_read_direct, &display); | |
3976 | |
3977 png_image_free(image); | |
3978 return result; | |
3979 } | |
3980 | |
3981 else | |
3982 return png_image_error(image, | |
3983 "png_image_finish_read[color-map]: no color-map"); | |
3984 } | |
3985 | |
3986 else | |
3987 return png_image_error(image, | |
3988 "png_image_finish_read: invalid argument"); | |
3989 } | |
3990 | |
3991 else if (image != NULL) | |
3992 return png_image_error(image, | |
3993 "png_image_finish_read: damaged PNG_IMAGE_VERSION"); | |
3994 | |
3995 return 0; | |
3996 } | |
3997 | |
3998 #endif /* PNG_SIMPLIFIED_READ_SUPPORTED */ | |
3999 #endif /* PNG_READ_SUPPORTED */ | |
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