src/third-party/libpng/pngwutil.c (view raw)
1
2/* pngwutil.c - utilities to write a PNG file
3 *
4 * Last changed in libpng 1.6.17 [March 26, 2015]
5 * Copyright (c) 1998-2015 Glenn Randers-Pehrson
6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
8 *
9 * This code is released under the libpng license.
10 * For conditions of distribution and use, see the disclaimer
11 * and license in png.h
12 */
13
14#include "pngpriv.h"
15
16#ifdef PNG_WRITE_SUPPORTED
17
18#ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
19/* Place a 32-bit number into a buffer in PNG byte order. We work
20 * with unsigned numbers for convenience, although one supported
21 * ancillary chunk uses signed (two's complement) numbers.
22 */
23void PNGAPI
24png_save_uint_32(png_bytep buf, png_uint_32 i)
25{
26 buf[0] = (png_byte)(i >> 24);
27 buf[1] = (png_byte)(i >> 16);
28 buf[2] = (png_byte)(i >> 8);
29 buf[3] = (png_byte)(i );
30}
31
32/* Place a 16-bit number into a buffer in PNG byte order.
33 * The parameter is declared unsigned int, not png_uint_16,
34 * just to avoid potential problems on pre-ANSI C compilers.
35 */
36void PNGAPI
37png_save_uint_16(png_bytep buf, unsigned int i)
38{
39 buf[0] = (png_byte)(i >> 8);
40 buf[1] = (png_byte)(i );
41}
42#endif
43
44/* Simple function to write the signature. If we have already written
45 * the magic bytes of the signature, or more likely, the PNG stream is
46 * being embedded into another stream and doesn't need its own signature,
47 * we should call png_set_sig_bytes() to tell libpng how many of the
48 * bytes have already been written.
49 */
50void PNGAPI
51png_write_sig(png_structrp png_ptr)
52{
53 png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
54
55#ifdef PNG_IO_STATE_SUPPORTED
56 /* Inform the I/O callback that the signature is being written */
57 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_SIGNATURE;
58#endif
59
60 /* Write the rest of the 8 byte signature */
61 png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes],
62 (png_size_t)(8 - png_ptr->sig_bytes));
63
64 if (png_ptr->sig_bytes < 3)
65 png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
66}
67
68/* Write the start of a PNG chunk. The type is the chunk type.
69 * The total_length is the sum of the lengths of all the data you will be
70 * passing in png_write_chunk_data().
71 */
72static void
73png_write_chunk_header(png_structrp png_ptr, png_uint_32 chunk_name,
74 png_uint_32 length)
75{
76 png_byte buf[8];
77
78#if defined(PNG_DEBUG) && (PNG_DEBUG > 0)
79 PNG_CSTRING_FROM_CHUNK(buf, chunk_name);
80 png_debug2(0, "Writing %s chunk, length = %lu", buf, (unsigned long)length);
81#endif
82
83 if (png_ptr == NULL)
84 return;
85
86#ifdef PNG_IO_STATE_SUPPORTED
87 /* Inform the I/O callback that the chunk header is being written.
88 * PNG_IO_CHUNK_HDR requires a single I/O call.
89 */
90 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_HDR;
91#endif
92
93 /* Write the length and the chunk name */
94 png_save_uint_32(buf, length);
95 png_save_uint_32(buf + 4, chunk_name);
96 png_write_data(png_ptr, buf, 8);
97
98 /* Put the chunk name into png_ptr->chunk_name */
99 png_ptr->chunk_name = chunk_name;
100
101 /* Reset the crc and run it over the chunk name */
102 png_reset_crc(png_ptr);
103
104 png_calculate_crc(png_ptr, buf + 4, 4);
105
106#ifdef PNG_IO_STATE_SUPPORTED
107 /* Inform the I/O callback that chunk data will (possibly) be written.
108 * PNG_IO_CHUNK_DATA does NOT require a specific number of I/O calls.
109 */
110 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_DATA;
111#endif
112}
113
114void PNGAPI
115png_write_chunk_start(png_structrp png_ptr, png_const_bytep chunk_string,
116 png_uint_32 length)
117{
118 png_write_chunk_header(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), length);
119}
120
121/* Write the data of a PNG chunk started with png_write_chunk_header().
122 * Note that multiple calls to this function are allowed, and that the
123 * sum of the lengths from these calls *must* add up to the total_length
124 * given to png_write_chunk_header().
125 */
126void PNGAPI
127png_write_chunk_data(png_structrp png_ptr, png_const_bytep data,
128 png_size_t length)
129{
130 /* Write the data, and run the CRC over it */
131 if (png_ptr == NULL)
132 return;
133
134 if (data != NULL && length > 0)
135 {
136 png_write_data(png_ptr, data, length);
137
138 /* Update the CRC after writing the data,
139 * in case the user I/O routine alters it.
140 */
141 png_calculate_crc(png_ptr, data, length);
142 }
143}
144
145/* Finish a chunk started with png_write_chunk_header(). */
146void PNGAPI
147png_write_chunk_end(png_structrp png_ptr)
148{
149 png_byte buf[4];
150
151 if (png_ptr == NULL) return;
152
153#ifdef PNG_IO_STATE_SUPPORTED
154 /* Inform the I/O callback that the chunk CRC is being written.
155 * PNG_IO_CHUNK_CRC requires a single I/O function call.
156 */
157 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_CRC;
158#endif
159
160 /* Write the crc in a single operation */
161 png_save_uint_32(buf, png_ptr->crc);
162
163 png_write_data(png_ptr, buf, (png_size_t)4);
164}
165
166/* Write a PNG chunk all at once. The type is an array of ASCII characters
167 * representing the chunk name. The array must be at least 4 bytes in
168 * length, and does not need to be null terminated. To be safe, pass the
169 * pre-defined chunk names here, and if you need a new one, define it
170 * where the others are defined. The length is the length of the data.
171 * All the data must be present. If that is not possible, use the
172 * png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end()
173 * functions instead.
174 */
175static void
176png_write_complete_chunk(png_structrp png_ptr, png_uint_32 chunk_name,
177 png_const_bytep data, png_size_t length)
178{
179 if (png_ptr == NULL)
180 return;
181
182 /* On 64 bit architectures 'length' may not fit in a png_uint_32. */
183 if (length > PNG_UINT_31_MAX)
184 png_error(png_ptr, "length exceeds PNG maximum");
185
186 png_write_chunk_header(png_ptr, chunk_name, (png_uint_32)length);
187 png_write_chunk_data(png_ptr, data, length);
188 png_write_chunk_end(png_ptr);
189}
190
191/* This is the API that calls the internal function above. */
192void PNGAPI
193png_write_chunk(png_structrp png_ptr, png_const_bytep chunk_string,
194 png_const_bytep data, png_size_t length)
195{
196 png_write_complete_chunk(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), data,
197 length);
198}
199
200/* This is used below to find the size of an image to pass to png_deflate_claim,
201 * so it only needs to be accurate if the size is less than 16384 bytes (the
202 * point at which a lower LZ window size can be used.)
203 */
204static png_alloc_size_t
205png_image_size(png_structrp png_ptr)
206{
207 /* Only return sizes up to the maximum of a png_uint_32; do this by limiting
208 * the width and height used to 15 bits.
209 */
210 png_uint_32 h = png_ptr->height;
211
212 if (png_ptr->rowbytes < 32768 && h < 32768)
213 {
214 if (png_ptr->interlaced != 0)
215 {
216 /* Interlacing makes the image larger because of the replication of
217 * both the filter byte and the padding to a byte boundary.
218 */
219 png_uint_32 w = png_ptr->width;
220 unsigned int pd = png_ptr->pixel_depth;
221 png_alloc_size_t cb_base;
222 int pass;
223
224 for (cb_base=0, pass=0; pass<=6; ++pass)
225 {
226 png_uint_32 pw = PNG_PASS_COLS(w, pass);
227
228 if (pw > 0)
229 cb_base += (PNG_ROWBYTES(pd, pw)+1) * PNG_PASS_ROWS(h, pass);
230 }
231
232 return cb_base;
233 }
234
235 else
236 return (png_ptr->rowbytes+1) * h;
237 }
238
239 else
240 return 0xffffffffU;
241}
242
243#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
244 /* This is the code to hack the first two bytes of the deflate stream (the
245 * deflate header) to correct the windowBits value to match the actual data
246 * size. Note that the second argument is the *uncompressed* size but the
247 * first argument is the *compressed* data (and it must be deflate
248 * compressed.)
249 */
250static void
251optimize_cmf(png_bytep data, png_alloc_size_t data_size)
252{
253 /* Optimize the CMF field in the zlib stream. The resultant zlib stream is
254 * still compliant to the stream specification.
255 */
256 if (data_size <= 16384) /* else windowBits must be 15 */
257 {
258 unsigned int z_cmf = data[0]; /* zlib compression method and flags */
259
260 if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
261 {
262 unsigned int z_cinfo;
263 unsigned int half_z_window_size;
264
265 z_cinfo = z_cmf >> 4;
266 half_z_window_size = 1U << (z_cinfo + 7);
267
268 if (data_size <= half_z_window_size) /* else no change */
269 {
270 unsigned int tmp;
271
272 do
273 {
274 half_z_window_size >>= 1;
275 --z_cinfo;
276 }
277 while (z_cinfo > 0 && data_size <= half_z_window_size);
278
279 z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
280
281 data[0] = (png_byte)z_cmf;
282 tmp = data[1] & 0xe0;
283 tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
284 data[1] = (png_byte)tmp;
285 }
286 }
287 }
288}
289#endif /* WRITE_OPTIMIZE_CMF */
290
291/* Initialize the compressor for the appropriate type of compression. */
292static int
293png_deflate_claim(png_structrp png_ptr, png_uint_32 owner,
294 png_alloc_size_t data_size)
295{
296 if (png_ptr->zowner != 0)
297 {
298#if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_ERROR_TEXT_SUPPORTED)
299 char msg[64];
300
301 PNG_STRING_FROM_CHUNK(msg, owner);
302 msg[4] = ':';
303 msg[5] = ' ';
304 PNG_STRING_FROM_CHUNK(msg+6, png_ptr->zowner);
305 /* So the message that results is "<chunk> using zstream"; this is an
306 * internal error, but is very useful for debugging. i18n requirements
307 * are minimal.
308 */
309 (void)png_safecat(msg, (sizeof msg), 10, " using zstream");
310#endif
311#if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC
312 png_warning(png_ptr, msg);
313
314 /* Attempt sane error recovery */
315 if (png_ptr->zowner == png_IDAT) /* don't steal from IDAT */
316 {
317 png_ptr->zstream.msg = PNGZ_MSG_CAST("in use by IDAT");
318 return Z_STREAM_ERROR;
319 }
320
321 png_ptr->zowner = 0;
322#else
323 png_error(png_ptr, msg);
324#endif
325 }
326
327 {
328 int level = png_ptr->zlib_level;
329 int method = png_ptr->zlib_method;
330 int windowBits = png_ptr->zlib_window_bits;
331 int memLevel = png_ptr->zlib_mem_level;
332 int strategy; /* set below */
333 int ret; /* zlib return code */
334
335 if (owner == png_IDAT)
336 {
337 if ((png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY) != 0)
338 strategy = png_ptr->zlib_strategy;
339
340 else if (png_ptr->do_filter != PNG_FILTER_NONE)
341 strategy = PNG_Z_DEFAULT_STRATEGY;
342
343 else
344 strategy = PNG_Z_DEFAULT_NOFILTER_STRATEGY;
345 }
346
347 else
348 {
349#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
350 level = png_ptr->zlib_text_level;
351 method = png_ptr->zlib_text_method;
352 windowBits = png_ptr->zlib_text_window_bits;
353 memLevel = png_ptr->zlib_text_mem_level;
354 strategy = png_ptr->zlib_text_strategy;
355#else
356 /* If customization is not supported the values all come from the
357 * IDAT values except for the strategy, which is fixed to the
358 * default. (This is the pre-1.6.0 behavior too, although it was
359 * implemented in a very different way.)
360 */
361 strategy = Z_DEFAULT_STRATEGY;
362#endif
363 }
364
365 /* Adjust 'windowBits' down if larger than 'data_size'; to stop this
366 * happening just pass 32768 as the data_size parameter. Notice that zlib
367 * requires an extra 262 bytes in the window in addition to the data to be
368 * able to see the whole of the data, so if data_size+262 takes us to the
369 * next windowBits size we need to fix up the value later. (Because even
370 * though deflate needs the extra window, inflate does not!)
371 */
372 if (data_size <= 16384)
373 {
374 /* IMPLEMENTATION NOTE: this 'half_window_size' stuff is only here to
375 * work round a Microsoft Visual C misbehavior which, contrary to C-90,
376 * widens the result of the following shift to 64-bits if (and,
377 * apparently, only if) it is used in a test.
378 */
379 unsigned int half_window_size = 1U << (windowBits-1);
380
381 while (data_size + 262 <= half_window_size)
382 {
383 half_window_size >>= 1;
384 --windowBits;
385 }
386 }
387
388 /* Check against the previous initialized values, if any. */
389 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0 &&
390 (png_ptr->zlib_set_level != level ||
391 png_ptr->zlib_set_method != method ||
392 png_ptr->zlib_set_window_bits != windowBits ||
393 png_ptr->zlib_set_mem_level != memLevel ||
394 png_ptr->zlib_set_strategy != strategy))
395 {
396 if (deflateEnd(&png_ptr->zstream) != Z_OK)
397 png_warning(png_ptr, "deflateEnd failed (ignored)");
398
399 png_ptr->flags &= ~PNG_FLAG_ZSTREAM_INITIALIZED;
400 }
401
402 /* For safety clear out the input and output pointers (currently zlib
403 * doesn't use them on Init, but it might in the future).
404 */
405 png_ptr->zstream.next_in = NULL;
406 png_ptr->zstream.avail_in = 0;
407 png_ptr->zstream.next_out = NULL;
408 png_ptr->zstream.avail_out = 0;
409
410 /* Now initialize if required, setting the new parameters, otherwise just
411 * to a simple reset to the previous parameters.
412 */
413 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
414 ret = deflateReset(&png_ptr->zstream);
415
416 else
417 {
418 ret = deflateInit2(&png_ptr->zstream, level, method, windowBits,
419 memLevel, strategy);
420
421 if (ret == Z_OK)
422 png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
423 }
424
425 /* The return code is from either deflateReset or deflateInit2; they have
426 * pretty much the same set of error codes.
427 */
428 if (ret == Z_OK)
429 png_ptr->zowner = owner;
430
431 else
432 png_zstream_error(png_ptr, ret);
433
434 return ret;
435 }
436}
437
438/* Clean up (or trim) a linked list of compression buffers. */
439void /* PRIVATE */
440png_free_buffer_list(png_structrp png_ptr, png_compression_bufferp *listp)
441{
442 png_compression_bufferp list = *listp;
443
444 if (list != NULL)
445 {
446 *listp = NULL;
447
448 do
449 {
450 png_compression_bufferp next = list->next;
451
452 png_free(png_ptr, list);
453 list = next;
454 }
455 while (list != NULL);
456 }
457}
458
459#ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
460/* This pair of functions encapsulates the operation of (a) compressing a
461 * text string, and (b) issuing it later as a series of chunk data writes.
462 * The compression_state structure is shared context for these functions
463 * set up by the caller to allow access to the relevant local variables.
464 *
465 * compression_buffer (new in 1.6.0) is just a linked list of zbuffer_size
466 * temporary buffers. From 1.6.0 it is retained in png_struct so that it will
467 * be correctly freed in the event of a write error (previous implementations
468 * just leaked memory.)
469 */
470typedef struct
471{
472 png_const_bytep input; /* The uncompressed input data */
473 png_alloc_size_t input_len; /* Its length */
474 png_uint_32 output_len; /* Final compressed length */
475 png_byte output[1024]; /* First block of output */
476} compression_state;
477
478static void
479png_text_compress_init(compression_state *comp, png_const_bytep input,
480 png_alloc_size_t input_len)
481{
482 comp->input = input;
483 comp->input_len = input_len;
484 comp->output_len = 0;
485}
486
487/* Compress the data in the compression state input */
488static int
489png_text_compress(png_structrp png_ptr, png_uint_32 chunk_name,
490 compression_state *comp, png_uint_32 prefix_len)
491{
492 int ret;
493
494 /* To find the length of the output it is necessary to first compress the
495 * input. The result is buffered rather than using the two-pass algorithm
496 * that is used on the inflate side; deflate is assumed to be slower and a
497 * PNG writer is assumed to have more memory available than a PNG reader.
498 *
499 * IMPLEMENTATION NOTE: the zlib API deflateBound() can be used to find an
500 * upper limit on the output size, but it is always bigger than the input
501 * size so it is likely to be more efficient to use this linked-list
502 * approach.
503 */
504 ret = png_deflate_claim(png_ptr, chunk_name, comp->input_len);
505
506 if (ret != Z_OK)
507 return ret;
508
509 /* Set up the compression buffers, we need a loop here to avoid overflowing a
510 * uInt. Use ZLIB_IO_MAX to limit the input. The output is always limited
511 * by the output buffer size, so there is no need to check that. Since this
512 * is ANSI-C we know that an 'int', hence a uInt, is always at least 16 bits
513 * in size.
514 */
515 {
516 png_compression_bufferp *end = &png_ptr->zbuffer_list;
517 png_alloc_size_t input_len = comp->input_len; /* may be zero! */
518 png_uint_32 output_len;
519
520 /* zlib updates these for us: */
521 png_ptr->zstream.next_in = PNGZ_INPUT_CAST(comp->input);
522 png_ptr->zstream.avail_in = 0; /* Set below */
523 png_ptr->zstream.next_out = comp->output;
524 png_ptr->zstream.avail_out = (sizeof comp->output);
525
526 output_len = png_ptr->zstream.avail_out;
527
528 do
529 {
530 uInt avail_in = ZLIB_IO_MAX;
531
532 if (avail_in > input_len)
533 avail_in = (uInt)input_len;
534
535 input_len -= avail_in;
536
537 png_ptr->zstream.avail_in = avail_in;
538
539 if (png_ptr->zstream.avail_out == 0)
540 {
541 png_compression_buffer *next;
542
543 /* Chunk data is limited to 2^31 bytes in length, so the prefix
544 * length must be counted here.
545 */
546 if (output_len + prefix_len > PNG_UINT_31_MAX)
547 {
548 ret = Z_MEM_ERROR;
549 break;
550 }
551
552 /* Need a new (malloc'ed) buffer, but there may be one present
553 * already.
554 */
555 next = *end;
556 if (next == NULL)
557 {
558 next = png_voidcast(png_compression_bufferp, png_malloc_base
559 (png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr)));
560
561 if (next == NULL)
562 {
563 ret = Z_MEM_ERROR;
564 break;
565 }
566
567 /* Link in this buffer (so that it will be freed later) */
568 next->next = NULL;
569 *end = next;
570 }
571
572 png_ptr->zstream.next_out = next->output;
573 png_ptr->zstream.avail_out = png_ptr->zbuffer_size;
574 output_len += png_ptr->zstream.avail_out;
575
576 /* Move 'end' to the next buffer pointer. */
577 end = &next->next;
578 }
579
580 /* Compress the data */
581 ret = deflate(&png_ptr->zstream,
582 input_len > 0 ? Z_NO_FLUSH : Z_FINISH);
583
584 /* Claw back input data that was not consumed (because avail_in is
585 * reset above every time round the loop).
586 */
587 input_len += png_ptr->zstream.avail_in;
588 png_ptr->zstream.avail_in = 0; /* safety */
589 }
590 while (ret == Z_OK);
591
592 /* There may be some space left in the last output buffer. This needs to
593 * be subtracted from output_len.
594 */
595 output_len -= png_ptr->zstream.avail_out;
596 png_ptr->zstream.avail_out = 0; /* safety */
597 comp->output_len = output_len;
598
599 /* Now double check the output length, put in a custom message if it is
600 * too long. Otherwise ensure the z_stream::msg pointer is set to
601 * something.
602 */
603 if (output_len + prefix_len >= PNG_UINT_31_MAX)
604 {
605 png_ptr->zstream.msg = PNGZ_MSG_CAST("compressed data too long");
606 ret = Z_MEM_ERROR;
607 }
608
609 else
610 png_zstream_error(png_ptr, ret);
611
612 /* Reset zlib for another zTXt/iTXt or image data */
613 png_ptr->zowner = 0;
614
615 /* The only success case is Z_STREAM_END, input_len must be 0; if not this
616 * is an internal error.
617 */
618 if (ret == Z_STREAM_END && input_len == 0)
619 {
620#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
621 /* Fix up the deflate header, if required */
622 optimize_cmf(comp->output, comp->input_len);
623#endif
624 /* But Z_OK is returned, not Z_STREAM_END; this allows the claim
625 * function above to return Z_STREAM_END on an error (though it never
626 * does in the current versions of zlib.)
627 */
628 return Z_OK;
629 }
630
631 else
632 return ret;
633 }
634}
635
636/* Ship the compressed text out via chunk writes */
637static void
638png_write_compressed_data_out(png_structrp png_ptr, compression_state *comp)
639{
640 png_uint_32 output_len = comp->output_len;
641 png_const_bytep output = comp->output;
642 png_uint_32 avail = (sizeof comp->output);
643 png_compression_buffer *next = png_ptr->zbuffer_list;
644
645 for (;;)
646 {
647 if (avail > output_len)
648 avail = output_len;
649
650 png_write_chunk_data(png_ptr, output, avail);
651
652 output_len -= avail;
653
654 if (output_len == 0 || next == NULL)
655 break;
656
657 avail = png_ptr->zbuffer_size;
658 output = next->output;
659 next = next->next;
660 }
661
662 /* This is an internal error; 'next' must have been NULL! */
663 if (output_len > 0)
664 png_error(png_ptr, "error writing ancillary chunked compressed data");
665}
666#endif /* WRITE_COMPRESSED_TEXT */
667
668#if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \
669 defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
670/* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification,
671 * and if invalid, correct the keyword rather than discarding the entire
672 * chunk. The PNG 1.0 specification requires keywords 1-79 characters in
673 * length, forbids leading or trailing whitespace, multiple internal spaces,
674 * and the non-break space (0x80) from ISO 8859-1. Returns keyword length.
675 *
676 * The 'new_key' buffer must be 80 characters in size (for the keyword plus a
677 * trailing '\0'). If this routine returns 0 then there was no keyword, or a
678 * valid one could not be generated, and the caller must png_error.
679 */
680static png_uint_32
681png_check_keyword(png_structrp png_ptr, png_const_charp key, png_bytep new_key)
682{
683 png_const_charp orig_key = key;
684 png_uint_32 key_len = 0;
685 int bad_character = 0;
686 int space = 1;
687
688 png_debug(1, "in png_check_keyword");
689
690 if (key == NULL)
691 {
692 *new_key = 0;
693 return 0;
694 }
695
696 while (*key && key_len < 79)
697 {
698 png_byte ch = (png_byte)*key++;
699
700 if ((ch > 32 && ch <= 126) || (ch >= 161 /*&& ch <= 255*/))
701 *new_key++ = ch, ++key_len, space = 0;
702
703 else if (space == 0)
704 {
705 /* A space or an invalid character when one wasn't seen immediately
706 * before; output just a space.
707 */
708 *new_key++ = 32, ++key_len, space = 1;
709
710 /* If the character was not a space then it is invalid. */
711 if (ch != 32)
712 bad_character = ch;
713 }
714
715 else if (bad_character == 0)
716 bad_character = ch; /* just skip it, record the first error */
717 }
718
719 if (key_len > 0 && space != 0) /* trailing space */
720 {
721 --key_len, --new_key;
722 if (bad_character == 0)
723 bad_character = 32;
724 }
725
726 /* Terminate the keyword */
727 *new_key = 0;
728
729 if (key_len == 0)
730 return 0;
731
732#ifdef PNG_WARNINGS_SUPPORTED
733 /* Try to only output one warning per keyword: */
734 if (*key != 0) /* keyword too long */
735 png_warning(png_ptr, "keyword truncated");
736
737 else if (bad_character != 0)
738 {
739 PNG_WARNING_PARAMETERS(p)
740
741 png_warning_parameter(p, 1, orig_key);
742 png_warning_parameter_signed(p, 2, PNG_NUMBER_FORMAT_02x, bad_character);
743
744 png_formatted_warning(png_ptr, p, "keyword \"@1\": bad character '0x@2'");
745 }
746#endif /* WARNINGS */
747
748 return key_len;
749}
750#endif /* WRITE_TEXT || WRITE_pCAL || WRITE_iCCP || WRITE_sPLT */
751
752/* Write the IHDR chunk, and update the png_struct with the necessary
753 * information. Note that the rest of this code depends upon this
754 * information being correct.
755 */
756void /* PRIVATE */
757png_write_IHDR(png_structrp png_ptr, png_uint_32 width, png_uint_32 height,
758 int bit_depth, int color_type, int compression_type, int filter_type,
759 int interlace_type)
760{
761 png_byte buf[13]; /* Buffer to store the IHDR info */
762
763 png_debug(1, "in png_write_IHDR");
764
765 /* Check that we have valid input data from the application info */
766 switch (color_type)
767 {
768 case PNG_COLOR_TYPE_GRAY:
769 switch (bit_depth)
770 {
771 case 1:
772 case 2:
773 case 4:
774 case 8:
775#ifdef PNG_WRITE_16BIT_SUPPORTED
776 case 16:
777#endif
778 png_ptr->channels = 1; break;
779
780 default:
781 png_error(png_ptr,
782 "Invalid bit depth for grayscale image");
783 }
784 break;
785
786 case PNG_COLOR_TYPE_RGB:
787#ifdef PNG_WRITE_16BIT_SUPPORTED
788 if (bit_depth != 8 && bit_depth != 16)
789#else
790 if (bit_depth != 8)
791#endif
792 png_error(png_ptr, "Invalid bit depth for RGB image");
793
794 png_ptr->channels = 3;
795 break;
796
797 case PNG_COLOR_TYPE_PALETTE:
798 switch (bit_depth)
799 {
800 case 1:
801 case 2:
802 case 4:
803 case 8:
804 png_ptr->channels = 1;
805 break;
806
807 default:
808 png_error(png_ptr, "Invalid bit depth for paletted image");
809 }
810 break;
811
812 case PNG_COLOR_TYPE_GRAY_ALPHA:
813 if (bit_depth != 8 && bit_depth != 16)
814 png_error(png_ptr, "Invalid bit depth for grayscale+alpha image");
815
816 png_ptr->channels = 2;
817 break;
818
819 case PNG_COLOR_TYPE_RGB_ALPHA:
820#ifdef PNG_WRITE_16BIT_SUPPORTED
821 if (bit_depth != 8 && bit_depth != 16)
822#else
823 if (bit_depth != 8)
824#endif
825 png_error(png_ptr, "Invalid bit depth for RGBA image");
826
827 png_ptr->channels = 4;
828 break;
829
830 default:
831 png_error(png_ptr, "Invalid image color type specified");
832 }
833
834 if (compression_type != PNG_COMPRESSION_TYPE_BASE)
835 {
836 png_warning(png_ptr, "Invalid compression type specified");
837 compression_type = PNG_COMPRESSION_TYPE_BASE;
838 }
839
840 /* Write filter_method 64 (intrapixel differencing) only if
841 * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
842 * 2. Libpng did not write a PNG signature (this filter_method is only
843 * used in PNG datastreams that are embedded in MNG datastreams) and
844 * 3. The application called png_permit_mng_features with a mask that
845 * included PNG_FLAG_MNG_FILTER_64 and
846 * 4. The filter_method is 64 and
847 * 5. The color_type is RGB or RGBA
848 */
849 if (
850#ifdef PNG_MNG_FEATURES_SUPPORTED
851 !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
852 ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
853 (color_type == PNG_COLOR_TYPE_RGB ||
854 color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&
855 (filter_type == PNG_INTRAPIXEL_DIFFERENCING)) &&
856#endif
857 filter_type != PNG_FILTER_TYPE_BASE)
858 {
859 png_warning(png_ptr, "Invalid filter type specified");
860 filter_type = PNG_FILTER_TYPE_BASE;
861 }
862
863#ifdef PNG_WRITE_INTERLACING_SUPPORTED
864 if (interlace_type != PNG_INTERLACE_NONE &&
865 interlace_type != PNG_INTERLACE_ADAM7)
866 {
867 png_warning(png_ptr, "Invalid interlace type specified");
868 interlace_type = PNG_INTERLACE_ADAM7;
869 }
870#else
871 interlace_type=PNG_INTERLACE_NONE;
872#endif
873
874 /* Save the relevant information */
875 png_ptr->bit_depth = (png_byte)bit_depth;
876 png_ptr->color_type = (png_byte)color_type;
877 png_ptr->interlaced = (png_byte)interlace_type;
878#ifdef PNG_MNG_FEATURES_SUPPORTED
879 png_ptr->filter_type = (png_byte)filter_type;
880#endif
881 png_ptr->compression_type = (png_byte)compression_type;
882 png_ptr->width = width;
883 png_ptr->height = height;
884
885 png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels);
886 png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width);
887 /* Set the usr info, so any transformations can modify it */
888 png_ptr->usr_width = png_ptr->width;
889 png_ptr->usr_bit_depth = png_ptr->bit_depth;
890 png_ptr->usr_channels = png_ptr->channels;
891
892 /* Pack the header information into the buffer */
893 png_save_uint_32(buf, width);
894 png_save_uint_32(buf + 4, height);
895 buf[8] = (png_byte)bit_depth;
896 buf[9] = (png_byte)color_type;
897 buf[10] = (png_byte)compression_type;
898 buf[11] = (png_byte)filter_type;
899 buf[12] = (png_byte)interlace_type;
900
901 /* Write the chunk */
902 png_write_complete_chunk(png_ptr, png_IHDR, buf, (png_size_t)13);
903
904 if ((png_ptr->do_filter) == PNG_NO_FILTERS)
905 {
906 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
907 png_ptr->bit_depth < 8)
908 png_ptr->do_filter = PNG_FILTER_NONE;
909
910 else
911 png_ptr->do_filter = PNG_ALL_FILTERS;
912 }
913
914 png_ptr->mode = PNG_HAVE_IHDR; /* not READY_FOR_ZTXT */
915}
916
917/* Write the palette. We are careful not to trust png_color to be in the
918 * correct order for PNG, so people can redefine it to any convenient
919 * structure.
920 */
921void /* PRIVATE */
922png_write_PLTE(png_structrp png_ptr, png_const_colorp palette,
923 png_uint_32 num_pal)
924{
925 png_uint_32 i;
926 png_const_colorp pal_ptr;
927 png_byte buf[3];
928
929 png_debug(1, "in png_write_PLTE");
930
931 if ((
932#ifdef PNG_MNG_FEATURES_SUPPORTED
933 (png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0 &&
934#endif
935 num_pal == 0) || num_pal > 256)
936 {
937 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
938 {
939 png_error(png_ptr, "Invalid number of colors in palette");
940 }
941
942 else
943 {
944 png_warning(png_ptr, "Invalid number of colors in palette");
945 return;
946 }
947 }
948
949 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
950 {
951 png_warning(png_ptr,
952 "Ignoring request to write a PLTE chunk in grayscale PNG");
953
954 return;
955 }
956
957 png_ptr->num_palette = (png_uint_16)num_pal;
958 png_debug1(3, "num_palette = %d", png_ptr->num_palette);
959
960 png_write_chunk_header(png_ptr, png_PLTE, (png_uint_32)(num_pal * 3));
961#ifdef PNG_POINTER_INDEXING_SUPPORTED
962
963 for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++)
964 {
965 buf[0] = pal_ptr->red;
966 buf[1] = pal_ptr->green;
967 buf[2] = pal_ptr->blue;
968 png_write_chunk_data(png_ptr, buf, (png_size_t)3);
969 }
970
971#else
972 /* This is a little slower but some buggy compilers need to do this
973 * instead
974 */
975 pal_ptr=palette;
976
977 for (i = 0; i < num_pal; i++)
978 {
979 buf[0] = pal_ptr[i].red;
980 buf[1] = pal_ptr[i].green;
981 buf[2] = pal_ptr[i].blue;
982 png_write_chunk_data(png_ptr, buf, (png_size_t)3);
983 }
984
985#endif
986 png_write_chunk_end(png_ptr);
987 png_ptr->mode |= PNG_HAVE_PLTE;
988}
989
990/* This is similar to png_text_compress, above, except that it does not require
991 * all of the data at once and, instead of buffering the compressed result,
992 * writes it as IDAT chunks. Unlike png_text_compress it *can* png_error out
993 * because it calls the write interface. As a result it does its own error
994 * reporting and does not return an error code. In the event of error it will
995 * just call png_error. The input data length may exceed 32-bits. The 'flush'
996 * parameter is exactly the same as that to deflate, with the following
997 * meanings:
998 *
999 * Z_NO_FLUSH: normal incremental output of compressed data
1000 * Z_SYNC_FLUSH: do a SYNC_FLUSH, used by png_write_flush
1001 * Z_FINISH: this is the end of the input, do a Z_FINISH and clean up
1002 *
1003 * The routine manages the acquire and release of the png_ptr->zstream by
1004 * checking and (at the end) clearing png_ptr->zowner; it does some sanity
1005 * checks on the 'mode' flags while doing this.
1006 */
1007void /* PRIVATE */
1008png_compress_IDAT(png_structrp png_ptr, png_const_bytep input,
1009 png_alloc_size_t input_len, int flush)
1010{
1011 if (png_ptr->zowner != png_IDAT)
1012 {
1013 /* First time. Ensure we have a temporary buffer for compression and
1014 * trim the buffer list if it has more than one entry to free memory.
1015 * If 'WRITE_COMPRESSED_TEXT' is not set the list will never have been
1016 * created at this point, but the check here is quick and safe.
1017 */
1018 if (png_ptr->zbuffer_list == NULL)
1019 {
1020 png_ptr->zbuffer_list = png_voidcast(png_compression_bufferp,
1021 png_malloc(png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr)));
1022 png_ptr->zbuffer_list->next = NULL;
1023 }
1024
1025 else
1026 png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list->next);
1027
1028 /* It is a terminal error if we can't claim the zstream. */
1029 if (png_deflate_claim(png_ptr, png_IDAT, png_image_size(png_ptr)) != Z_OK)
1030 png_error(png_ptr, png_ptr->zstream.msg);
1031
1032 /* The output state is maintained in png_ptr->zstream, so it must be
1033 * initialized here after the claim.
1034 */
1035 png_ptr->zstream.next_out = png_ptr->zbuffer_list->output;
1036 png_ptr->zstream.avail_out = png_ptr->zbuffer_size;
1037 }
1038
1039 /* Now loop reading and writing until all the input is consumed or an error
1040 * terminates the operation. The _out values are maintained across calls to
1041 * this function, but the input must be reset each time.
1042 */
1043 png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
1044 png_ptr->zstream.avail_in = 0; /* set below */
1045 for (;;)
1046 {
1047 int ret;
1048
1049 /* INPUT: from the row data */
1050 uInt avail = ZLIB_IO_MAX;
1051
1052 if (avail > input_len)
1053 avail = (uInt)input_len; /* safe because of the check */
1054
1055 png_ptr->zstream.avail_in = avail;
1056 input_len -= avail;
1057
1058 ret = deflate(&png_ptr->zstream, input_len > 0 ? Z_NO_FLUSH : flush);
1059
1060 /* Include as-yet unconsumed input */
1061 input_len += png_ptr->zstream.avail_in;
1062 png_ptr->zstream.avail_in = 0;
1063
1064 /* OUTPUT: write complete IDAT chunks when avail_out drops to zero. Note
1065 * that these two zstream fields are preserved across the calls, therefore
1066 * there is no need to set these up on entry to the loop.
1067 */
1068 if (png_ptr->zstream.avail_out == 0)
1069 {
1070 png_bytep data = png_ptr->zbuffer_list->output;
1071 uInt size = png_ptr->zbuffer_size;
1072
1073 /* Write an IDAT containing the data then reset the buffer. The
1074 * first IDAT may need deflate header optimization.
1075 */
1076#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
1077 if ((png_ptr->mode & PNG_HAVE_IDAT) == 0 &&
1078 png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
1079 optimize_cmf(data, png_image_size(png_ptr));
1080#endif
1081
1082 png_write_complete_chunk(png_ptr, png_IDAT, data, size);
1083 png_ptr->mode |= PNG_HAVE_IDAT;
1084
1085 png_ptr->zstream.next_out = data;
1086 png_ptr->zstream.avail_out = size;
1087
1088 /* For SYNC_FLUSH or FINISH it is essential to keep calling zlib with
1089 * the same flush parameter until it has finished output, for NO_FLUSH
1090 * it doesn't matter.
1091 */
1092 if (ret == Z_OK && flush != Z_NO_FLUSH)
1093 continue;
1094 }
1095
1096 /* The order of these checks doesn't matter much; it just affects which
1097 * possible error might be detected if multiple things go wrong at once.
1098 */
1099 if (ret == Z_OK) /* most likely return code! */
1100 {
1101 /* If all the input has been consumed then just return. If Z_FINISH
1102 * was used as the flush parameter something has gone wrong if we get
1103 * here.
1104 */
1105 if (input_len == 0)
1106 {
1107 if (flush == Z_FINISH)
1108 png_error(png_ptr, "Z_OK on Z_FINISH with output space");
1109
1110 return;
1111 }
1112 }
1113
1114 else if (ret == Z_STREAM_END && flush == Z_FINISH)
1115 {
1116 /* This is the end of the IDAT data; any pending output must be
1117 * flushed. For small PNG files we may still be at the beginning.
1118 */
1119 png_bytep data = png_ptr->zbuffer_list->output;
1120 uInt size = png_ptr->zbuffer_size - png_ptr->zstream.avail_out;
1121
1122#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
1123 if ((png_ptr->mode & PNG_HAVE_IDAT) == 0 &&
1124 png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
1125 optimize_cmf(data, png_image_size(png_ptr));
1126#endif
1127
1128 png_write_complete_chunk(png_ptr, png_IDAT, data, size);
1129 png_ptr->zstream.avail_out = 0;
1130 png_ptr->zstream.next_out = NULL;
1131 png_ptr->mode |= PNG_HAVE_IDAT | PNG_AFTER_IDAT;
1132
1133 png_ptr->zowner = 0; /* Release the stream */
1134 return;
1135 }
1136
1137 else
1138 {
1139 /* This is an error condition. */
1140 png_zstream_error(png_ptr, ret);
1141 png_error(png_ptr, png_ptr->zstream.msg);
1142 }
1143 }
1144}
1145
1146/* Write an IEND chunk */
1147void /* PRIVATE */
1148png_write_IEND(png_structrp png_ptr)
1149{
1150 png_debug(1, "in png_write_IEND");
1151
1152 png_write_complete_chunk(png_ptr, png_IEND, NULL, (png_size_t)0);
1153 png_ptr->mode |= PNG_HAVE_IEND;
1154}
1155
1156#ifdef PNG_WRITE_gAMA_SUPPORTED
1157/* Write a gAMA chunk */
1158void /* PRIVATE */
1159png_write_gAMA_fixed(png_structrp png_ptr, png_fixed_point file_gamma)
1160{
1161 png_byte buf[4];
1162
1163 png_debug(1, "in png_write_gAMA");
1164
1165 /* file_gamma is saved in 1/100,000ths */
1166 png_save_uint_32(buf, (png_uint_32)file_gamma);
1167 png_write_complete_chunk(png_ptr, png_gAMA, buf, (png_size_t)4);
1168}
1169#endif
1170
1171#ifdef PNG_WRITE_sRGB_SUPPORTED
1172/* Write a sRGB chunk */
1173void /* PRIVATE */
1174png_write_sRGB(png_structrp png_ptr, int srgb_intent)
1175{
1176 png_byte buf[1];
1177
1178 png_debug(1, "in png_write_sRGB");
1179
1180 if (srgb_intent >= PNG_sRGB_INTENT_LAST)
1181 png_warning(png_ptr,
1182 "Invalid sRGB rendering intent specified");
1183
1184 buf[0]=(png_byte)srgb_intent;
1185 png_write_complete_chunk(png_ptr, png_sRGB, buf, (png_size_t)1);
1186}
1187#endif
1188
1189#ifdef PNG_WRITE_iCCP_SUPPORTED
1190/* Write an iCCP chunk */
1191void /* PRIVATE */
1192png_write_iCCP(png_structrp png_ptr, png_const_charp name,
1193 png_const_bytep profile)
1194{
1195 png_uint_32 name_len;
1196 png_uint_32 profile_len;
1197 png_byte new_name[81]; /* 1 byte for the compression byte */
1198 compression_state comp;
1199 png_uint_32 temp;
1200
1201 png_debug(1, "in png_write_iCCP");
1202
1203 /* These are all internal problems: the profile should have been checked
1204 * before when it was stored.
1205 */
1206 if (profile == NULL)
1207 png_error(png_ptr, "No profile for iCCP chunk"); /* internal error */
1208
1209 profile_len = png_get_uint_32(profile);
1210
1211 if (profile_len < 132)
1212 png_error(png_ptr, "ICC profile too short");
1213
1214 temp = (png_uint_32) (*(profile+8));
1215 if (temp > 3 && (profile_len & 0x03))
1216 png_error(png_ptr, "ICC profile length invalid (not a multiple of 4)");
1217
1218 {
1219 png_uint_32 embedded_profile_len = png_get_uint_32(profile);
1220
1221 if (profile_len != embedded_profile_len)
1222 png_error(png_ptr, "Profile length does not match profile");
1223 }
1224
1225 name_len = png_check_keyword(png_ptr, name, new_name);
1226
1227 if (name_len == 0)
1228 png_error(png_ptr, "iCCP: invalid keyword");
1229
1230 new_name[++name_len] = PNG_COMPRESSION_TYPE_BASE;
1231
1232 /* Make sure we include the NULL after the name and the compression type */
1233 ++name_len;
1234
1235 png_text_compress_init(&comp, profile, profile_len);
1236
1237 /* Allow for keyword terminator and compression byte */
1238 if (png_text_compress(png_ptr, png_iCCP, &comp, name_len) != Z_OK)
1239 png_error(png_ptr, png_ptr->zstream.msg);
1240
1241 png_write_chunk_header(png_ptr, png_iCCP, name_len + comp.output_len);
1242
1243 png_write_chunk_data(png_ptr, new_name, name_len);
1244
1245 png_write_compressed_data_out(png_ptr, &comp);
1246
1247 png_write_chunk_end(png_ptr);
1248}
1249#endif
1250
1251#ifdef PNG_WRITE_sPLT_SUPPORTED
1252/* Write a sPLT chunk */
1253void /* PRIVATE */
1254png_write_sPLT(png_structrp png_ptr, png_const_sPLT_tp spalette)
1255{
1256 png_uint_32 name_len;
1257 png_byte new_name[80];
1258 png_byte entrybuf[10];
1259 png_size_t entry_size = (spalette->depth == 8 ? 6 : 10);
1260 png_size_t palette_size = entry_size * spalette->nentries;
1261 png_sPLT_entryp ep;
1262#ifndef PNG_POINTER_INDEXING_SUPPORTED
1263 int i;
1264#endif
1265
1266 png_debug(1, "in png_write_sPLT");
1267
1268 name_len = png_check_keyword(png_ptr, spalette->name, new_name);
1269
1270 if (name_len == 0)
1271 png_error(png_ptr, "sPLT: invalid keyword");
1272
1273 /* Make sure we include the NULL after the name */
1274 png_write_chunk_header(png_ptr, png_sPLT,
1275 (png_uint_32)(name_len + 2 + palette_size));
1276
1277 png_write_chunk_data(png_ptr, (png_bytep)new_name,
1278 (png_size_t)(name_len + 1));
1279
1280 png_write_chunk_data(png_ptr, &spalette->depth, (png_size_t)1);
1281
1282 /* Loop through each palette entry, writing appropriately */
1283#ifdef PNG_POINTER_INDEXING_SUPPORTED
1284 for (ep = spalette->entries; ep<spalette->entries + spalette->nentries; ep++)
1285 {
1286 if (spalette->depth == 8)
1287 {
1288 entrybuf[0] = (png_byte)ep->red;
1289 entrybuf[1] = (png_byte)ep->green;
1290 entrybuf[2] = (png_byte)ep->blue;
1291 entrybuf[3] = (png_byte)ep->alpha;
1292 png_save_uint_16(entrybuf + 4, ep->frequency);
1293 }
1294
1295 else
1296 {
1297 png_save_uint_16(entrybuf + 0, ep->red);
1298 png_save_uint_16(entrybuf + 2, ep->green);
1299 png_save_uint_16(entrybuf + 4, ep->blue);
1300 png_save_uint_16(entrybuf + 6, ep->alpha);
1301 png_save_uint_16(entrybuf + 8, ep->frequency);
1302 }
1303
1304 png_write_chunk_data(png_ptr, entrybuf, entry_size);
1305 }
1306#else
1307 ep=spalette->entries;
1308 for (i = 0; i>spalette->nentries; i++)
1309 {
1310 if (spalette->depth == 8)
1311 {
1312 entrybuf[0] = (png_byte)ep[i].red;
1313 entrybuf[1] = (png_byte)ep[i].green;
1314 entrybuf[2] = (png_byte)ep[i].blue;
1315 entrybuf[3] = (png_byte)ep[i].alpha;
1316 png_save_uint_16(entrybuf + 4, ep[i].frequency);
1317 }
1318
1319 else
1320 {
1321 png_save_uint_16(entrybuf + 0, ep[i].red);
1322 png_save_uint_16(entrybuf + 2, ep[i].green);
1323 png_save_uint_16(entrybuf + 4, ep[i].blue);
1324 png_save_uint_16(entrybuf + 6, ep[i].alpha);
1325 png_save_uint_16(entrybuf + 8, ep[i].frequency);
1326 }
1327
1328 png_write_chunk_data(png_ptr, entrybuf, entry_size);
1329 }
1330#endif
1331
1332 png_write_chunk_end(png_ptr);
1333}
1334#endif
1335
1336#ifdef PNG_WRITE_sBIT_SUPPORTED
1337/* Write the sBIT chunk */
1338void /* PRIVATE */
1339png_write_sBIT(png_structrp png_ptr, png_const_color_8p sbit, int color_type)
1340{
1341 png_byte buf[4];
1342 png_size_t size;
1343
1344 png_debug(1, "in png_write_sBIT");
1345
1346 /* Make sure we don't depend upon the order of PNG_COLOR_8 */
1347 if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
1348 {
1349 png_byte maxbits;
1350
1351 maxbits = (png_byte)(color_type==PNG_COLOR_TYPE_PALETTE ? 8 :
1352 png_ptr->usr_bit_depth);
1353
1354 if (sbit->red == 0 || sbit->red > maxbits ||
1355 sbit->green == 0 || sbit->green > maxbits ||
1356 sbit->blue == 0 || sbit->blue > maxbits)
1357 {
1358 png_warning(png_ptr, "Invalid sBIT depth specified");
1359 return;
1360 }
1361
1362 buf[0] = sbit->red;
1363 buf[1] = sbit->green;
1364 buf[2] = sbit->blue;
1365 size = 3;
1366 }
1367
1368 else
1369 {
1370 if (sbit->gray == 0 || sbit->gray > png_ptr->usr_bit_depth)
1371 {
1372 png_warning(png_ptr, "Invalid sBIT depth specified");
1373 return;
1374 }
1375
1376 buf[0] = sbit->gray;
1377 size = 1;
1378 }
1379
1380 if ((color_type & PNG_COLOR_MASK_ALPHA) != 0)
1381 {
1382 if (sbit->alpha == 0 || sbit->alpha > png_ptr->usr_bit_depth)
1383 {
1384 png_warning(png_ptr, "Invalid sBIT depth specified");
1385 return;
1386 }
1387
1388 buf[size++] = sbit->alpha;
1389 }
1390
1391 png_write_complete_chunk(png_ptr, png_sBIT, buf, size);
1392}
1393#endif
1394
1395#ifdef PNG_WRITE_cHRM_SUPPORTED
1396/* Write the cHRM chunk */
1397void /* PRIVATE */
1398png_write_cHRM_fixed(png_structrp png_ptr, const png_xy *xy)
1399{
1400 png_byte buf[32];
1401
1402 png_debug(1, "in png_write_cHRM");
1403
1404 /* Each value is saved in 1/100,000ths */
1405 png_save_int_32(buf, xy->whitex);
1406 png_save_int_32(buf + 4, xy->whitey);
1407
1408 png_save_int_32(buf + 8, xy->redx);
1409 png_save_int_32(buf + 12, xy->redy);
1410
1411 png_save_int_32(buf + 16, xy->greenx);
1412 png_save_int_32(buf + 20, xy->greeny);
1413
1414 png_save_int_32(buf + 24, xy->bluex);
1415 png_save_int_32(buf + 28, xy->bluey);
1416
1417 png_write_complete_chunk(png_ptr, png_cHRM, buf, 32);
1418}
1419#endif
1420
1421#ifdef PNG_WRITE_tRNS_SUPPORTED
1422/* Write the tRNS chunk */
1423void /* PRIVATE */
1424png_write_tRNS(png_structrp png_ptr, png_const_bytep trans_alpha,
1425 png_const_color_16p tran, int num_trans, int color_type)
1426{
1427 png_byte buf[6];
1428
1429 png_debug(1, "in png_write_tRNS");
1430
1431 if (color_type == PNG_COLOR_TYPE_PALETTE)
1432 {
1433 if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette)
1434 {
1435 png_app_warning(png_ptr,
1436 "Invalid number of transparent colors specified");
1437 return;
1438 }
1439
1440 /* Write the chunk out as it is */
1441 png_write_complete_chunk(png_ptr, png_tRNS, trans_alpha,
1442 (png_size_t)num_trans);
1443 }
1444
1445 else if (color_type == PNG_COLOR_TYPE_GRAY)
1446 {
1447 /* One 16 bit value */
1448 if (tran->gray >= (1 << png_ptr->bit_depth))
1449 {
1450 png_app_warning(png_ptr,
1451 "Ignoring attempt to write tRNS chunk out-of-range for bit_depth");
1452
1453 return;
1454 }
1455
1456 png_save_uint_16(buf, tran->gray);
1457 png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)2);
1458 }
1459
1460 else if (color_type == PNG_COLOR_TYPE_RGB)
1461 {
1462 /* Three 16 bit values */
1463 png_save_uint_16(buf, tran->red);
1464 png_save_uint_16(buf + 2, tran->green);
1465 png_save_uint_16(buf + 4, tran->blue);
1466#ifdef PNG_WRITE_16BIT_SUPPORTED
1467 if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]) != 0)
1468#else
1469 if ((buf[0] | buf[2] | buf[4]) != 0)
1470#endif
1471 {
1472 png_app_warning(png_ptr,
1473 "Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8");
1474 return;
1475 }
1476
1477 png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)6);
1478 }
1479
1480 else
1481 {
1482 png_app_warning(png_ptr, "Can't write tRNS with an alpha channel");
1483 }
1484}
1485#endif
1486
1487#ifdef PNG_WRITE_bKGD_SUPPORTED
1488/* Write the background chunk */
1489void /* PRIVATE */
1490png_write_bKGD(png_structrp png_ptr, png_const_color_16p back, int color_type)
1491{
1492 png_byte buf[6];
1493
1494 png_debug(1, "in png_write_bKGD");
1495
1496 if (color_type == PNG_COLOR_TYPE_PALETTE)
1497 {
1498 if (
1499#ifdef PNG_MNG_FEATURES_SUPPORTED
1500 (png_ptr->num_palette != 0 ||
1501 (png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0) &&
1502#endif
1503 back->index >= png_ptr->num_palette)
1504 {
1505 png_warning(png_ptr, "Invalid background palette index");
1506 return;
1507 }
1508
1509 buf[0] = back->index;
1510 png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)1);
1511 }
1512
1513 else if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
1514 {
1515 png_save_uint_16(buf, back->red);
1516 png_save_uint_16(buf + 2, back->green);
1517 png_save_uint_16(buf + 4, back->blue);
1518#ifdef PNG_WRITE_16BIT_SUPPORTED
1519 if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]) != 0)
1520#else
1521 if ((buf[0] | buf[2] | buf[4]) != 0)
1522#endif
1523 {
1524 png_warning(png_ptr,
1525 "Ignoring attempt to write 16-bit bKGD chunk when bit_depth is 8");
1526
1527 return;
1528 }
1529
1530 png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)6);
1531 }
1532
1533 else
1534 {
1535 if (back->gray >= (1 << png_ptr->bit_depth))
1536 {
1537 png_warning(png_ptr,
1538 "Ignoring attempt to write bKGD chunk out-of-range for bit_depth");
1539
1540 return;
1541 }
1542
1543 png_save_uint_16(buf, back->gray);
1544 png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)2);
1545 }
1546}
1547#endif
1548
1549#ifdef PNG_WRITE_hIST_SUPPORTED
1550/* Write the histogram */
1551void /* PRIVATE */
1552png_write_hIST(png_structrp png_ptr, png_const_uint_16p hist, int num_hist)
1553{
1554 int i;
1555 png_byte buf[3];
1556
1557 png_debug(1, "in png_write_hIST");
1558
1559 if (num_hist > (int)png_ptr->num_palette)
1560 {
1561 png_debug2(3, "num_hist = %d, num_palette = %d", num_hist,
1562 png_ptr->num_palette);
1563
1564 png_warning(png_ptr, "Invalid number of histogram entries specified");
1565 return;
1566 }
1567
1568 png_write_chunk_header(png_ptr, png_hIST, (png_uint_32)(num_hist * 2));
1569
1570 for (i = 0; i < num_hist; i++)
1571 {
1572 png_save_uint_16(buf, hist[i]);
1573 png_write_chunk_data(png_ptr, buf, (png_size_t)2);
1574 }
1575
1576 png_write_chunk_end(png_ptr);
1577}
1578#endif
1579
1580#ifdef PNG_WRITE_tEXt_SUPPORTED
1581/* Write a tEXt chunk */
1582void /* PRIVATE */
1583png_write_tEXt(png_structrp png_ptr, png_const_charp key, png_const_charp text,
1584 png_size_t text_len)
1585{
1586 png_uint_32 key_len;
1587 png_byte new_key[80];
1588
1589 png_debug(1, "in png_write_tEXt");
1590
1591 key_len = png_check_keyword(png_ptr, key, new_key);
1592
1593 if (key_len == 0)
1594 png_error(png_ptr, "tEXt: invalid keyword");
1595
1596 if (text == NULL || *text == '\0')
1597 text_len = 0;
1598
1599 else
1600 text_len = strlen(text);
1601
1602 if (text_len > PNG_UINT_31_MAX - (key_len+1))
1603 png_error(png_ptr, "tEXt: text too long");
1604
1605 /* Make sure we include the 0 after the key */
1606 png_write_chunk_header(png_ptr, png_tEXt,
1607 (png_uint_32)/*checked above*/(key_len + text_len + 1));
1608 /*
1609 * We leave it to the application to meet PNG-1.0 requirements on the
1610 * contents of the text. PNG-1.0 through PNG-1.2 discourage the use of
1611 * any non-Latin-1 characters except for NEWLINE. ISO PNG will forbid them.
1612 * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1613 */
1614 png_write_chunk_data(png_ptr, new_key, key_len + 1);
1615
1616 if (text_len != 0)
1617 png_write_chunk_data(png_ptr, (png_const_bytep)text, text_len);
1618
1619 png_write_chunk_end(png_ptr);
1620}
1621#endif
1622
1623#ifdef PNG_WRITE_zTXt_SUPPORTED
1624/* Write a compressed text chunk */
1625void /* PRIVATE */
1626png_write_zTXt(png_structrp png_ptr, png_const_charp key, png_const_charp text,
1627 int compression)
1628{
1629 png_uint_32 key_len;
1630 png_byte new_key[81];
1631 compression_state comp;
1632
1633 png_debug(1, "in png_write_zTXt");
1634
1635 if (compression == PNG_TEXT_COMPRESSION_NONE)
1636 {
1637 png_write_tEXt(png_ptr, key, text, 0);
1638 return;
1639 }
1640
1641 if (compression != PNG_TEXT_COMPRESSION_zTXt)
1642 png_error(png_ptr, "zTXt: invalid compression type");
1643
1644 key_len = png_check_keyword(png_ptr, key, new_key);
1645
1646 if (key_len == 0)
1647 png_error(png_ptr, "zTXt: invalid keyword");
1648
1649 /* Add the compression method and 1 for the keyword separator. */
1650 new_key[++key_len] = PNG_COMPRESSION_TYPE_BASE;
1651 ++key_len;
1652
1653 /* Compute the compressed data; do it now for the length */
1654 png_text_compress_init(&comp, (png_const_bytep)text,
1655 text == NULL ? 0 : strlen(text));
1656
1657 if (png_text_compress(png_ptr, png_zTXt, &comp, key_len) != Z_OK)
1658 png_error(png_ptr, png_ptr->zstream.msg);
1659
1660 /* Write start of chunk */
1661 png_write_chunk_header(png_ptr, png_zTXt, key_len + comp.output_len);
1662
1663 /* Write key */
1664 png_write_chunk_data(png_ptr, new_key, key_len);
1665
1666 /* Write the compressed data */
1667 png_write_compressed_data_out(png_ptr, &comp);
1668
1669 /* Close the chunk */
1670 png_write_chunk_end(png_ptr);
1671}
1672#endif
1673
1674#ifdef PNG_WRITE_iTXt_SUPPORTED
1675/* Write an iTXt chunk */
1676void /* PRIVATE */
1677png_write_iTXt(png_structrp png_ptr, int compression, png_const_charp key,
1678 png_const_charp lang, png_const_charp lang_key, png_const_charp text)
1679{
1680 png_uint_32 key_len, prefix_len;
1681 png_size_t lang_len, lang_key_len;
1682 png_byte new_key[82];
1683 compression_state comp;
1684
1685 png_debug(1, "in png_write_iTXt");
1686
1687 key_len = png_check_keyword(png_ptr, key, new_key);
1688
1689 if (key_len == 0)
1690 png_error(png_ptr, "iTXt: invalid keyword");
1691
1692 /* Set the compression flag */
1693 switch (compression)
1694 {
1695 case PNG_ITXT_COMPRESSION_NONE:
1696 case PNG_TEXT_COMPRESSION_NONE:
1697 compression = new_key[++key_len] = 0; /* no compression */
1698 break;
1699
1700 case PNG_TEXT_COMPRESSION_zTXt:
1701 case PNG_ITXT_COMPRESSION_zTXt:
1702 compression = new_key[++key_len] = 1; /* compressed */
1703 break;
1704
1705 default:
1706 png_error(png_ptr, "iTXt: invalid compression");
1707 }
1708
1709 new_key[++key_len] = PNG_COMPRESSION_TYPE_BASE;
1710 ++key_len; /* for the keywod separator */
1711
1712 /* We leave it to the application to meet PNG-1.0 requirements on the
1713 * contents of the text. PNG-1.0 through PNG-1.2 discourage the use of
1714 * any non-Latin-1 characters except for NEWLINE. ISO PNG, however,
1715 * specifies that the text is UTF-8 and this really doesn't require any
1716 * checking.
1717 *
1718 * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1719 *
1720 * TODO: validate the language tag correctly (see the spec.)
1721 */
1722 if (lang == NULL) lang = ""; /* empty language is valid */
1723 lang_len = strlen(lang)+1;
1724 if (lang_key == NULL) lang_key = ""; /* may be empty */
1725 lang_key_len = strlen(lang_key)+1;
1726 if (text == NULL) text = ""; /* may be empty */
1727
1728 prefix_len = key_len;
1729 if (lang_len > PNG_UINT_31_MAX-prefix_len)
1730 prefix_len = PNG_UINT_31_MAX;
1731 else
1732 prefix_len = (png_uint_32)(prefix_len + lang_len);
1733
1734 if (lang_key_len > PNG_UINT_31_MAX-prefix_len)
1735 prefix_len = PNG_UINT_31_MAX;
1736 else
1737 prefix_len = (png_uint_32)(prefix_len + lang_key_len);
1738
1739 png_text_compress_init(&comp, (png_const_bytep)text, strlen(text));
1740
1741 if (compression != 0)
1742 {
1743 if (png_text_compress(png_ptr, png_iTXt, &comp, prefix_len) != Z_OK)
1744 png_error(png_ptr, png_ptr->zstream.msg);
1745 }
1746
1747 else
1748 {
1749 if (comp.input_len > PNG_UINT_31_MAX-prefix_len)
1750 png_error(png_ptr, "iTXt: uncompressed text too long");
1751
1752 /* So the string will fit in a chunk: */
1753 comp.output_len = (png_uint_32)/*SAFE*/comp.input_len;
1754 }
1755
1756 png_write_chunk_header(png_ptr, png_iTXt, comp.output_len + prefix_len);
1757
1758 png_write_chunk_data(png_ptr, new_key, key_len);
1759
1760 png_write_chunk_data(png_ptr, (png_const_bytep)lang, lang_len);
1761
1762 png_write_chunk_data(png_ptr, (png_const_bytep)lang_key, lang_key_len);
1763
1764 if (compression != 0)
1765 png_write_compressed_data_out(png_ptr, &comp);
1766
1767 else
1768 png_write_chunk_data(png_ptr, (png_const_bytep)text, comp.output_len);
1769
1770 png_write_chunk_end(png_ptr);
1771}
1772#endif
1773
1774#ifdef PNG_WRITE_oFFs_SUPPORTED
1775/* Write the oFFs chunk */
1776void /* PRIVATE */
1777png_write_oFFs(png_structrp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
1778 int unit_type)
1779{
1780 png_byte buf[9];
1781
1782 png_debug(1, "in png_write_oFFs");
1783
1784 if (unit_type >= PNG_OFFSET_LAST)
1785 png_warning(png_ptr, "Unrecognized unit type for oFFs chunk");
1786
1787 png_save_int_32(buf, x_offset);
1788 png_save_int_32(buf + 4, y_offset);
1789 buf[8] = (png_byte)unit_type;
1790
1791 png_write_complete_chunk(png_ptr, png_oFFs, buf, (png_size_t)9);
1792}
1793#endif
1794#ifdef PNG_WRITE_pCAL_SUPPORTED
1795/* Write the pCAL chunk (described in the PNG extensions document) */
1796void /* PRIVATE */
1797png_write_pCAL(png_structrp png_ptr, png_charp purpose, png_int_32 X0,
1798 png_int_32 X1, int type, int nparams, png_const_charp units,
1799 png_charpp params)
1800{
1801 png_uint_32 purpose_len;
1802 png_size_t units_len, total_len;
1803 png_size_tp params_len;
1804 png_byte buf[10];
1805 png_byte new_purpose[80];
1806 int i;
1807
1808 png_debug1(1, "in png_write_pCAL (%d parameters)", nparams);
1809
1810 if (type >= PNG_EQUATION_LAST)
1811 png_error(png_ptr, "Unrecognized equation type for pCAL chunk");
1812
1813 purpose_len = png_check_keyword(png_ptr, purpose, new_purpose);
1814
1815 if (purpose_len == 0)
1816 png_error(png_ptr, "pCAL: invalid keyword");
1817
1818 ++purpose_len; /* terminator */
1819
1820 png_debug1(3, "pCAL purpose length = %d", (int)purpose_len);
1821 units_len = strlen(units) + (nparams == 0 ? 0 : 1);
1822 png_debug1(3, "pCAL units length = %d", (int)units_len);
1823 total_len = purpose_len + units_len + 10;
1824
1825 params_len = (png_size_tp)png_malloc(png_ptr,
1826 (png_alloc_size_t)(nparams * (sizeof (png_size_t))));
1827
1828 /* Find the length of each parameter, making sure we don't count the
1829 * null terminator for the last parameter.
1830 */
1831 for (i = 0; i < nparams; i++)
1832 {
1833 params_len[i] = strlen(params[i]) + (i == nparams - 1 ? 0 : 1);
1834 png_debug2(3, "pCAL parameter %d length = %lu", i,
1835 (unsigned long)params_len[i]);
1836 total_len += params_len[i];
1837 }
1838
1839 png_debug1(3, "pCAL total length = %d", (int)total_len);
1840 png_write_chunk_header(png_ptr, png_pCAL, (png_uint_32)total_len);
1841 png_write_chunk_data(png_ptr, new_purpose, purpose_len);
1842 png_save_int_32(buf, X0);
1843 png_save_int_32(buf + 4, X1);
1844 buf[8] = (png_byte)type;
1845 buf[9] = (png_byte)nparams;
1846 png_write_chunk_data(png_ptr, buf, (png_size_t)10);
1847 png_write_chunk_data(png_ptr, (png_const_bytep)units, (png_size_t)units_len);
1848
1849 for (i = 0; i < nparams; i++)
1850 {
1851 png_write_chunk_data(png_ptr, (png_const_bytep)params[i], params_len[i]);
1852 }
1853
1854 png_free(png_ptr, params_len);
1855 png_write_chunk_end(png_ptr);
1856}
1857#endif
1858
1859#ifdef PNG_WRITE_sCAL_SUPPORTED
1860/* Write the sCAL chunk */
1861void /* PRIVATE */
1862png_write_sCAL_s(png_structrp png_ptr, int unit, png_const_charp width,
1863 png_const_charp height)
1864{
1865 png_byte buf[64];
1866 png_size_t wlen, hlen, total_len;
1867
1868 png_debug(1, "in png_write_sCAL_s");
1869
1870 wlen = strlen(width);
1871 hlen = strlen(height);
1872 total_len = wlen + hlen + 2;
1873
1874 if (total_len > 64)
1875 {
1876 png_warning(png_ptr, "Can't write sCAL (buffer too small)");
1877 return;
1878 }
1879
1880 buf[0] = (png_byte)unit;
1881 memcpy(buf + 1, width, wlen + 1); /* Append the '\0' here */
1882 memcpy(buf + wlen + 2, height, hlen); /* Do NOT append the '\0' here */
1883
1884 png_debug1(3, "sCAL total length = %u", (unsigned int)total_len);
1885 png_write_complete_chunk(png_ptr, png_sCAL, buf, total_len);
1886}
1887#endif
1888
1889#ifdef PNG_WRITE_pHYs_SUPPORTED
1890/* Write the pHYs chunk */
1891void /* PRIVATE */
1892png_write_pHYs(png_structrp png_ptr, png_uint_32 x_pixels_per_unit,
1893 png_uint_32 y_pixels_per_unit,
1894 int unit_type)
1895{
1896 png_byte buf[9];
1897
1898 png_debug(1, "in png_write_pHYs");
1899
1900 if (unit_type >= PNG_RESOLUTION_LAST)
1901 png_warning(png_ptr, "Unrecognized unit type for pHYs chunk");
1902
1903 png_save_uint_32(buf, x_pixels_per_unit);
1904 png_save_uint_32(buf + 4, y_pixels_per_unit);
1905 buf[8] = (png_byte)unit_type;
1906
1907 png_write_complete_chunk(png_ptr, png_pHYs, buf, (png_size_t)9);
1908}
1909#endif
1910
1911#ifdef PNG_WRITE_tIME_SUPPORTED
1912/* Write the tIME chunk. Use either png_convert_from_struct_tm()
1913 * or png_convert_from_time_t(), or fill in the structure yourself.
1914 */
1915void /* PRIVATE */
1916png_write_tIME(png_structrp png_ptr, png_const_timep mod_time)
1917{
1918 png_byte buf[7];
1919
1920 png_debug(1, "in png_write_tIME");
1921
1922 if (mod_time->month > 12 || mod_time->month < 1 ||
1923 mod_time->day > 31 || mod_time->day < 1 ||
1924 mod_time->hour > 23 || mod_time->second > 60)
1925 {
1926 png_warning(png_ptr, "Invalid time specified for tIME chunk");
1927 return;
1928 }
1929
1930 png_save_uint_16(buf, mod_time->year);
1931 buf[2] = mod_time->month;
1932 buf[3] = mod_time->day;
1933 buf[4] = mod_time->hour;
1934 buf[5] = mod_time->minute;
1935 buf[6] = mod_time->second;
1936
1937 png_write_complete_chunk(png_ptr, png_tIME, buf, (png_size_t)7);
1938}
1939#endif
1940
1941/* Initializes the row writing capability of libpng */
1942void /* PRIVATE */
1943png_write_start_row(png_structrp png_ptr)
1944{
1945#ifdef PNG_WRITE_INTERLACING_SUPPORTED
1946 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1947
1948 /* Start of interlace block */
1949 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
1950
1951 /* Offset to next interlace block */
1952 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
1953
1954 /* Start of interlace block in the y direction */
1955 static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
1956
1957 /* Offset to next interlace block in the y direction */
1958 static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
1959#endif
1960
1961 png_alloc_size_t buf_size;
1962 int usr_pixel_depth;
1963
1964 png_debug(1, "in png_write_start_row");
1965
1966 usr_pixel_depth = png_ptr->usr_channels * png_ptr->usr_bit_depth;
1967 buf_size = PNG_ROWBYTES(usr_pixel_depth, png_ptr->width) + 1;
1968
1969 /* 1.5.6: added to allow checking in the row write code. */
1970 png_ptr->transformed_pixel_depth = png_ptr->pixel_depth;
1971 png_ptr->maximum_pixel_depth = (png_byte)usr_pixel_depth;
1972
1973 /* Set up row buffer */
1974 png_ptr->row_buf = (png_bytep)png_malloc(png_ptr, buf_size);
1975
1976 png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE;
1977
1978#ifdef PNG_WRITE_FILTER_SUPPORTED
1979 /* Set up filtering buffer, if using this filter */
1980 if (png_ptr->do_filter & PNG_FILTER_SUB)
1981 {
1982 png_ptr->sub_row = (png_bytep)png_malloc(png_ptr, png_ptr->rowbytes + 1);
1983
1984 png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
1985 }
1986
1987 /* We only need to keep the previous row if we are using one of these. */
1988 if ((png_ptr->do_filter &
1989 (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH)) != 0)
1990 {
1991 /* Set up previous row buffer */
1992 png_ptr->prev_row = (png_bytep)png_calloc(png_ptr, buf_size);
1993
1994 if ((png_ptr->do_filter & PNG_FILTER_UP) != 0)
1995 {
1996 png_ptr->up_row = (png_bytep)png_malloc(png_ptr,
1997 png_ptr->rowbytes + 1);
1998
1999 png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;
2000 }
2001
2002 if ((png_ptr->do_filter & PNG_FILTER_AVG) != 0)
2003 {
2004 png_ptr->avg_row = (png_bytep)png_malloc(png_ptr,
2005 png_ptr->rowbytes + 1);
2006
2007 png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;
2008 }
2009
2010 if ((png_ptr->do_filter & PNG_FILTER_PAETH) != 0)
2011 {
2012 png_ptr->paeth_row = (png_bytep)png_malloc(png_ptr,
2013 png_ptr->rowbytes + 1);
2014
2015 png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
2016 }
2017 }
2018#endif /* WRITE_FILTER */
2019
2020#ifdef PNG_WRITE_INTERLACING_SUPPORTED
2021 /* If interlaced, we need to set up width and height of pass */
2022 if (png_ptr->interlaced != 0)
2023 {
2024 if ((png_ptr->transformations & PNG_INTERLACE) == 0)
2025 {
2026 png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
2027 png_pass_ystart[0]) / png_pass_yinc[0];
2028
2029 png_ptr->usr_width = (png_ptr->width + png_pass_inc[0] - 1 -
2030 png_pass_start[0]) / png_pass_inc[0];
2031 }
2032
2033 else
2034 {
2035 png_ptr->num_rows = png_ptr->height;
2036 png_ptr->usr_width = png_ptr->width;
2037 }
2038 }
2039
2040 else
2041#endif
2042 {
2043 png_ptr->num_rows = png_ptr->height;
2044 png_ptr->usr_width = png_ptr->width;
2045 }
2046}
2047
2048/* Internal use only. Called when finished processing a row of data. */
2049void /* PRIVATE */
2050png_write_finish_row(png_structrp png_ptr)
2051{
2052#ifdef PNG_WRITE_INTERLACING_SUPPORTED
2053 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
2054
2055 /* Start of interlace block */
2056 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
2057
2058 /* Offset to next interlace block */
2059 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
2060
2061 /* Start of interlace block in the y direction */
2062 static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
2063
2064 /* Offset to next interlace block in the y direction */
2065 static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
2066#endif
2067
2068 png_debug(1, "in png_write_finish_row");
2069
2070 /* Next row */
2071 png_ptr->row_number++;
2072
2073 /* See if we are done */
2074 if (png_ptr->row_number < png_ptr->num_rows)
2075 return;
2076
2077#ifdef PNG_WRITE_INTERLACING_SUPPORTED
2078 /* If interlaced, go to next pass */
2079 if (png_ptr->interlaced != 0)
2080 {
2081 png_ptr->row_number = 0;
2082 if ((png_ptr->transformations & PNG_INTERLACE) != 0)
2083 {
2084 png_ptr->pass++;
2085 }
2086
2087 else
2088 {
2089 /* Loop until we find a non-zero width or height pass */
2090 do
2091 {
2092 png_ptr->pass++;
2093
2094 if (png_ptr->pass >= 7)
2095 break;
2096
2097 png_ptr->usr_width = (png_ptr->width +
2098 png_pass_inc[png_ptr->pass] - 1 -
2099 png_pass_start[png_ptr->pass]) /
2100 png_pass_inc[png_ptr->pass];
2101
2102 png_ptr->num_rows = (png_ptr->height +
2103 png_pass_yinc[png_ptr->pass] - 1 -
2104 png_pass_ystart[png_ptr->pass]) /
2105 png_pass_yinc[png_ptr->pass];
2106
2107 if ((png_ptr->transformations & PNG_INTERLACE) != 0)
2108 break;
2109
2110 } while (png_ptr->usr_width == 0 || png_ptr->num_rows == 0);
2111
2112 }
2113
2114 /* Reset the row above the image for the next pass */
2115 if (png_ptr->pass < 7)
2116 {
2117 if (png_ptr->prev_row != NULL)
2118 memset(png_ptr->prev_row, 0,
2119 (png_size_t)(PNG_ROWBYTES(png_ptr->usr_channels*
2120 png_ptr->usr_bit_depth, png_ptr->width)) + 1);
2121
2122 return;
2123 }
2124 }
2125#endif
2126
2127 /* If we get here, we've just written the last row, so we need
2128 to flush the compressor */
2129 png_compress_IDAT(png_ptr, NULL, 0, Z_FINISH);
2130}
2131
2132#ifdef PNG_WRITE_INTERLACING_SUPPORTED
2133/* Pick out the correct pixels for the interlace pass.
2134 * The basic idea here is to go through the row with a source
2135 * pointer and a destination pointer (sp and dp), and copy the
2136 * correct pixels for the pass. As the row gets compacted,
2137 * sp will always be >= dp, so we should never overwrite anything.
2138 * See the default: case for the easiest code to understand.
2139 */
2140void /* PRIVATE */
2141png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
2142{
2143 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
2144
2145 /* Start of interlace block */
2146 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
2147
2148 /* Offset to next interlace block */
2149 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
2150
2151 png_debug(1, "in png_do_write_interlace");
2152
2153 /* We don't have to do anything on the last pass (6) */
2154 if (pass < 6)
2155 {
2156 /* Each pixel depth is handled separately */
2157 switch (row_info->pixel_depth)
2158 {
2159 case 1:
2160 {
2161 png_bytep sp;
2162 png_bytep dp;
2163 int shift;
2164 int d;
2165 int value;
2166 png_uint_32 i;
2167 png_uint_32 row_width = row_info->width;
2168
2169 dp = row;
2170 d = 0;
2171 shift = 7;
2172
2173 for (i = png_pass_start[pass]; i < row_width;
2174 i += png_pass_inc[pass])
2175 {
2176 sp = row + (png_size_t)(i >> 3);
2177 value = (int)(*sp >> (7 - (int)(i & 0x07))) & 0x01;
2178 d |= (value << shift);
2179
2180 if (shift == 0)
2181 {
2182 shift = 7;
2183 *dp++ = (png_byte)d;
2184 d = 0;
2185 }
2186
2187 else
2188 shift--;
2189
2190 }
2191 if (shift != 7)
2192 *dp = (png_byte)d;
2193
2194 break;
2195 }
2196
2197 case 2:
2198 {
2199 png_bytep sp;
2200 png_bytep dp;
2201 int shift;
2202 int d;
2203 int value;
2204 png_uint_32 i;
2205 png_uint_32 row_width = row_info->width;
2206
2207 dp = row;
2208 shift = 6;
2209 d = 0;
2210
2211 for (i = png_pass_start[pass]; i < row_width;
2212 i += png_pass_inc[pass])
2213 {
2214 sp = row + (png_size_t)(i >> 2);
2215 value = (*sp >> ((3 - (int)(i & 0x03)) << 1)) & 0x03;
2216 d |= (value << shift);
2217
2218 if (shift == 0)
2219 {
2220 shift = 6;
2221 *dp++ = (png_byte)d;
2222 d = 0;
2223 }
2224
2225 else
2226 shift -= 2;
2227 }
2228 if (shift != 6)
2229 *dp = (png_byte)d;
2230
2231 break;
2232 }
2233
2234 case 4:
2235 {
2236 png_bytep sp;
2237 png_bytep dp;
2238 int shift;
2239 int d;
2240 int value;
2241 png_uint_32 i;
2242 png_uint_32 row_width = row_info->width;
2243
2244 dp = row;
2245 shift = 4;
2246 d = 0;
2247 for (i = png_pass_start[pass]; i < row_width;
2248 i += png_pass_inc[pass])
2249 {
2250 sp = row + (png_size_t)(i >> 1);
2251 value = (*sp >> ((1 - (int)(i & 0x01)) << 2)) & 0x0f;
2252 d |= (value << shift);
2253
2254 if (shift == 0)
2255 {
2256 shift = 4;
2257 *dp++ = (png_byte)d;
2258 d = 0;
2259 }
2260
2261 else
2262 shift -= 4;
2263 }
2264 if (shift != 4)
2265 *dp = (png_byte)d;
2266
2267 break;
2268 }
2269
2270 default:
2271 {
2272 png_bytep sp;
2273 png_bytep dp;
2274 png_uint_32 i;
2275 png_uint_32 row_width = row_info->width;
2276 png_size_t pixel_bytes;
2277
2278 /* Start at the beginning */
2279 dp = row;
2280
2281 /* Find out how many bytes each pixel takes up */
2282 pixel_bytes = (row_info->pixel_depth >> 3);
2283
2284 /* Loop through the row, only looking at the pixels that matter */
2285 for (i = png_pass_start[pass]; i < row_width;
2286 i += png_pass_inc[pass])
2287 {
2288 /* Find out where the original pixel is */
2289 sp = row + (png_size_t)i * pixel_bytes;
2290
2291 /* Move the pixel */
2292 if (dp != sp)
2293 memcpy(dp, sp, pixel_bytes);
2294
2295 /* Next pixel */
2296 dp += pixel_bytes;
2297 }
2298 break;
2299 }
2300 }
2301 /* Set new row width */
2302 row_info->width = (row_info->width +
2303 png_pass_inc[pass] - 1 -
2304 png_pass_start[pass]) /
2305 png_pass_inc[pass];
2306
2307 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
2308 row_info->width);
2309 }
2310}
2311#endif
2312
2313/* This filters the row, chooses which filter to use, if it has not already
2314 * been specified by the application, and then writes the row out with the
2315 * chosen filter.
2316 */
2317static void /* PRIVATE */
2318png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row,
2319 png_size_t row_bytes);
2320
2321#define PNG_MAXSUM (((png_uint_32)(-1)) >> 1)
2322#define PNG_HISHIFT 10
2323#define PNG_LOMASK ((png_uint_32)0xffffL)
2324#define PNG_HIMASK ((png_uint_32)(~PNG_LOMASK >> PNG_HISHIFT))
2325void /* PRIVATE */
2326png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
2327{
2328 png_bytep best_row;
2329#ifdef PNG_WRITE_FILTER_SUPPORTED
2330 png_bytep prev_row, row_buf;
2331 png_uint_32 mins, bpp;
2332 png_byte filter_to_do = png_ptr->do_filter;
2333 png_size_t row_bytes = row_info->rowbytes;
2334#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2335 int num_p_filters = png_ptr->num_prev_filters;
2336#endif
2337
2338 png_debug(1, "in png_write_find_filter");
2339
2340#ifndef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2341 if (png_ptr->row_number == 0 && filter_to_do == PNG_ALL_FILTERS)
2342 {
2343 /* These will never be selected so we need not test them. */
2344 filter_to_do &= ~(PNG_FILTER_UP | PNG_FILTER_PAETH);
2345 }
2346#endif
2347
2348 /* Find out how many bytes offset each pixel is */
2349 bpp = (row_info->pixel_depth + 7) >> 3;
2350
2351 prev_row = png_ptr->prev_row;
2352#endif
2353 best_row = png_ptr->row_buf;
2354#ifdef PNG_WRITE_FILTER_SUPPORTED
2355 row_buf = best_row;
2356 mins = PNG_MAXSUM;
2357
2358 /* The prediction method we use is to find which method provides the
2359 * smallest value when summing the absolute values of the distances
2360 * from zero, using anything >= 128 as negative numbers. This is known
2361 * as the "minimum sum of absolute differences" heuristic. Other
2362 * heuristics are the "weighted minimum sum of absolute differences"
2363 * (experimental and can in theory improve compression), and the "zlib
2364 * predictive" method (not implemented yet), which does test compressions
2365 * of lines using different filter methods, and then chooses the
2366 * (series of) filter(s) that give minimum compressed data size (VERY
2367 * computationally expensive).
2368 *
2369 * GRR 980525: consider also
2370 *
2371 * (1) minimum sum of absolute differences from running average (i.e.,
2372 * keep running sum of non-absolute differences & count of bytes)
2373 * [track dispersion, too? restart average if dispersion too large?]
2374 *
2375 * (1b) minimum sum of absolute differences from sliding average, probably
2376 * with window size <= deflate window (usually 32K)
2377 *
2378 * (2) minimum sum of squared differences from zero or running average
2379 * (i.e., ~ root-mean-square approach)
2380 */
2381
2382
2383 /* We don't need to test the 'no filter' case if this is the only filter
2384 * that has been chosen, as it doesn't actually do anything to the data.
2385 */
2386 if ((filter_to_do & PNG_FILTER_NONE) != 0 && filter_to_do != PNG_FILTER_NONE)
2387 {
2388 png_bytep rp;
2389 png_uint_32 sum = 0;
2390 png_size_t i;
2391 int v;
2392
2393 for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
2394 {
2395 v = *rp;
2396 sum += (v < 128) ? v : 256 - v;
2397 }
2398
2399#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2400 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2401 {
2402 png_uint_32 sumhi, sumlo;
2403 int j;
2404 sumlo = sum & PNG_LOMASK;
2405 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; /* Gives us some footroom */
2406
2407 /* Reduce the sum if we match any of the previous rows */
2408 for (j = 0; j < num_p_filters; j++)
2409 {
2410 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
2411 {
2412 sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2413 PNG_WEIGHT_SHIFT;
2414
2415 sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2416 PNG_WEIGHT_SHIFT;
2417 }
2418 }
2419
2420 /* Factor in the cost of this filter (this is here for completeness,
2421 * but it makes no sense to have a "cost" for the NONE filter, as
2422 * it has the minimum possible computational cost - none).
2423 */
2424 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
2425 PNG_COST_SHIFT;
2426
2427 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
2428 PNG_COST_SHIFT;
2429
2430 if (sumhi > PNG_HIMASK)
2431 sum = PNG_MAXSUM;
2432
2433 else
2434 sum = (sumhi << PNG_HISHIFT) + sumlo;
2435 }
2436#endif
2437 mins = sum;
2438 }
2439
2440 /* Sub filter */
2441 if (filter_to_do == PNG_FILTER_SUB)
2442 /* It's the only filter so no testing is needed */
2443 {
2444 png_bytep rp, lp, dp;
2445 png_size_t i;
2446
2447 for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
2448 i++, rp++, dp++)
2449 {
2450 *dp = *rp;
2451 }
2452
2453 for (lp = row_buf + 1; i < row_bytes;
2454 i++, rp++, lp++, dp++)
2455 {
2456 *dp = (png_byte)((int)*rp - (int)*lp);
2457 }
2458
2459 best_row = png_ptr->sub_row;
2460 }
2461
2462 else if ((filter_to_do & PNG_FILTER_SUB) != 0)
2463 {
2464 png_bytep rp, dp, lp;
2465 png_uint_32 sum = 0, lmins = mins;
2466 png_size_t i;
2467 int v;
2468
2469#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2470 /* We temporarily increase the "minimum sum" by the factor we
2471 * would reduce the sum of this filter, so that we can do the
2472 * early exit comparison without scaling the sum each time.
2473 */
2474 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2475 {
2476 int j;
2477 png_uint_32 lmhi, lmlo;
2478 lmlo = lmins & PNG_LOMASK;
2479 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2480
2481 for (j = 0; j < num_p_filters; j++)
2482 {
2483 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
2484 {
2485 lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2486 PNG_WEIGHT_SHIFT;
2487
2488 lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2489 PNG_WEIGHT_SHIFT;
2490 }
2491 }
2492
2493 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2494 PNG_COST_SHIFT;
2495
2496 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2497 PNG_COST_SHIFT;
2498
2499 if (lmhi > PNG_HIMASK)
2500 lmins = PNG_MAXSUM;
2501
2502 else
2503 lmins = (lmhi << PNG_HISHIFT) + lmlo;
2504 }
2505#endif
2506
2507 for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
2508 i++, rp++, dp++)
2509 {
2510 v = *dp = *rp;
2511
2512 sum += (v < 128) ? v : 256 - v;
2513 }
2514
2515 for (lp = row_buf + 1; i < row_bytes;
2516 i++, rp++, lp++, dp++)
2517 {
2518 v = *dp = (png_byte)((int)*rp - (int)*lp);
2519
2520 sum += (v < 128) ? v : 256 - v;
2521
2522 if (sum > lmins) /* We are already worse, don't continue. */
2523 break;
2524 }
2525
2526#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2527 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2528 {
2529 int j;
2530 png_uint_32 sumhi, sumlo;
2531 sumlo = sum & PNG_LOMASK;
2532 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2533
2534 for (j = 0; j < num_p_filters; j++)
2535 {
2536 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
2537 {
2538 sumlo = (sumlo * png_ptr->inv_filter_weights[j]) >>
2539 PNG_WEIGHT_SHIFT;
2540
2541 sumhi = (sumhi * png_ptr->inv_filter_weights[j]) >>
2542 PNG_WEIGHT_SHIFT;
2543 }
2544 }
2545
2546 sumlo = (sumlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2547 PNG_COST_SHIFT;
2548
2549 sumhi = (sumhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2550 PNG_COST_SHIFT;
2551
2552 if (sumhi > PNG_HIMASK)
2553 sum = PNG_MAXSUM;
2554
2555 else
2556 sum = (sumhi << PNG_HISHIFT) + sumlo;
2557 }
2558#endif
2559
2560 if (sum < mins)
2561 {
2562 mins = sum;
2563 best_row = png_ptr->sub_row;
2564 }
2565 }
2566
2567 /* Up filter */
2568 if (filter_to_do == PNG_FILTER_UP)
2569 {
2570 png_bytep rp, dp, pp;
2571 png_size_t i;
2572
2573 for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
2574 pp = prev_row + 1; i < row_bytes;
2575 i++, rp++, pp++, dp++)
2576 {
2577 *dp = (png_byte)((int)*rp - (int)*pp);
2578 }
2579
2580 best_row = png_ptr->up_row;
2581 }
2582
2583 else if ((filter_to_do & PNG_FILTER_UP) != 0)
2584 {
2585 png_bytep rp, dp, pp;
2586 png_uint_32 sum = 0, lmins = mins;
2587 png_size_t i;
2588 int v;
2589
2590
2591#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2592 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2593 {
2594 int j;
2595 png_uint_32 lmhi, lmlo;
2596 lmlo = lmins & PNG_LOMASK;
2597 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2598
2599 for (j = 0; j < num_p_filters; j++)
2600 {
2601 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
2602 {
2603 lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2604 PNG_WEIGHT_SHIFT;
2605
2606 lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2607 PNG_WEIGHT_SHIFT;
2608 }
2609 }
2610
2611 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
2612 PNG_COST_SHIFT;
2613
2614 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
2615 PNG_COST_SHIFT;
2616
2617 if (lmhi > PNG_HIMASK)
2618 lmins = PNG_MAXSUM;
2619
2620 else
2621 lmins = (lmhi << PNG_HISHIFT) + lmlo;
2622 }
2623#endif
2624
2625 for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
2626 pp = prev_row + 1; i < row_bytes; i++)
2627 {
2628 v = *dp++ = (png_byte)((int)*rp++ - (int)*pp++);
2629
2630 sum += (v < 128) ? v : 256 - v;
2631
2632 if (sum > lmins) /* We are already worse, don't continue. */
2633 break;
2634 }
2635
2636#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2637 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2638 {
2639 int j;
2640 png_uint_32 sumhi, sumlo;
2641 sumlo = sum & PNG_LOMASK;
2642 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2643
2644 for (j = 0; j < num_p_filters; j++)
2645 {
2646 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
2647 {
2648 sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2649 PNG_WEIGHT_SHIFT;
2650
2651 sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2652 PNG_WEIGHT_SHIFT;
2653 }
2654 }
2655
2656 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
2657 PNG_COST_SHIFT;
2658
2659 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
2660 PNG_COST_SHIFT;
2661
2662 if (sumhi > PNG_HIMASK)
2663 sum = PNG_MAXSUM;
2664
2665 else
2666 sum = (sumhi << PNG_HISHIFT) + sumlo;
2667 }
2668#endif
2669
2670 if (sum < mins)
2671 {
2672 mins = sum;
2673 best_row = png_ptr->up_row;
2674 }
2675 }
2676
2677 /* Avg filter */
2678 if (filter_to_do == PNG_FILTER_AVG)
2679 {
2680 png_bytep rp, dp, pp, lp;
2681 png_uint_32 i;
2682
2683 for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
2684 pp = prev_row + 1; i < bpp; i++)
2685 {
2686 *dp++ = (png_byte)((int)*rp++ - ((int)*pp++ / 2));
2687 }
2688
2689 for (lp = row_buf + 1; i < row_bytes; i++)
2690 {
2691 *dp++ =
2692 (png_byte)((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2));
2693 }
2694 best_row = png_ptr->avg_row;
2695 }
2696
2697 else if ((filter_to_do & PNG_FILTER_AVG) != 0)
2698 {
2699 png_bytep rp, dp, pp, lp;
2700 png_uint_32 sum = 0, lmins = mins;
2701 png_size_t i;
2702 int v;
2703
2704#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2705 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2706 {
2707 int j;
2708 png_uint_32 lmhi, lmlo;
2709 lmlo = lmins & PNG_LOMASK;
2710 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2711
2712 for (j = 0; j < num_p_filters; j++)
2713 {
2714 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_AVG)
2715 {
2716 lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2717 PNG_WEIGHT_SHIFT;
2718
2719 lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2720 PNG_WEIGHT_SHIFT;
2721 }
2722 }
2723
2724 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
2725 PNG_COST_SHIFT;
2726
2727 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
2728 PNG_COST_SHIFT;
2729
2730 if (lmhi > PNG_HIMASK)
2731 lmins = PNG_MAXSUM;
2732
2733 else
2734 lmins = (lmhi << PNG_HISHIFT) + lmlo;
2735 }
2736#endif
2737
2738 for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
2739 pp = prev_row + 1; i < bpp; i++)
2740 {
2741 v = *dp++ = (png_byte)((int)*rp++ - ((int)*pp++ / 2));
2742
2743 sum += (v < 128) ? v : 256 - v;
2744 }
2745
2746 for (lp = row_buf + 1; i < row_bytes; i++)
2747 {
2748 v = *dp++ =
2749 (png_byte)(((int)*rp++ - ((int)*pp++ + (int)*lp++) / 2));
2750
2751 sum += (v < 128) ? v : 256 - v;
2752
2753 if (sum > lmins) /* We are already worse, don't continue. */
2754 break;
2755 }
2756
2757#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2758 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2759 {
2760 int j;
2761 png_uint_32 sumhi, sumlo;
2762 sumlo = sum & PNG_LOMASK;
2763 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2764
2765 for (j = 0; j < num_p_filters; j++)
2766 {
2767 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
2768 {
2769 sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2770 PNG_WEIGHT_SHIFT;
2771
2772 sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2773 PNG_WEIGHT_SHIFT;
2774 }
2775 }
2776
2777 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
2778 PNG_COST_SHIFT;
2779
2780 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
2781 PNG_COST_SHIFT;
2782
2783 if (sumhi > PNG_HIMASK)
2784 sum = PNG_MAXSUM;
2785
2786 else
2787 sum = (sumhi << PNG_HISHIFT) + sumlo;
2788 }
2789#endif
2790
2791 if (sum < mins)
2792 {
2793 mins = sum;
2794 best_row = png_ptr->avg_row;
2795 }
2796 }
2797
2798 /* Paeth filter */
2799 if ((filter_to_do == PNG_FILTER_PAETH) != 0)
2800 {
2801 png_bytep rp, dp, pp, cp, lp;
2802 png_size_t i;
2803
2804 for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
2805 pp = prev_row + 1; i < bpp; i++)
2806 {
2807 *dp++ = (png_byte)((int)*rp++ - (int)*pp++);
2808 }
2809
2810 for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
2811 {
2812 int a, b, c, pa, pb, pc, p;
2813
2814 b = *pp++;
2815 c = *cp++;
2816 a = *lp++;
2817
2818 p = b - c;
2819 pc = a - c;
2820
2821#ifdef PNG_USE_ABS
2822 pa = abs(p);
2823 pb = abs(pc);
2824 pc = abs(p + pc);
2825#else
2826 pa = p < 0 ? -p : p;
2827 pb = pc < 0 ? -pc : pc;
2828 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
2829#endif
2830
2831 p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
2832
2833 *dp++ = (png_byte)((int)*rp++ - p);
2834 }
2835 best_row = png_ptr->paeth_row;
2836 }
2837
2838 else if ((filter_to_do & PNG_FILTER_PAETH) != 0)
2839 {
2840 png_bytep rp, dp, pp, cp, lp;
2841 png_uint_32 sum = 0, lmins = mins;
2842 png_size_t i;
2843 int v;
2844
2845#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2846 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2847 {
2848 int j;
2849 png_uint_32 lmhi, lmlo;
2850 lmlo = lmins & PNG_LOMASK;
2851 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2852
2853 for (j = 0; j < num_p_filters; j++)
2854 {
2855 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
2856 {
2857 lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2858 PNG_WEIGHT_SHIFT;
2859
2860 lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2861 PNG_WEIGHT_SHIFT;
2862 }
2863 }
2864
2865 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2866 PNG_COST_SHIFT;
2867
2868 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2869 PNG_COST_SHIFT;
2870
2871 if (lmhi > PNG_HIMASK)
2872 lmins = PNG_MAXSUM;
2873
2874 else
2875 lmins = (lmhi << PNG_HISHIFT) + lmlo;
2876 }
2877#endif
2878
2879 for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
2880 pp = prev_row + 1; i < bpp; i++)
2881 {
2882 v = *dp++ = (png_byte)((int)*rp++ - (int)*pp++);
2883
2884 sum += (v < 128) ? v : 256 - v;
2885 }
2886
2887 for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
2888 {
2889 int a, b, c, pa, pb, pc, p;
2890
2891 b = *pp++;
2892 c = *cp++;
2893 a = *lp++;
2894
2895#ifndef PNG_SLOW_PAETH
2896 p = b - c;
2897 pc = a - c;
2898#ifdef PNG_USE_ABS
2899 pa = abs(p);
2900 pb = abs(pc);
2901 pc = abs(p + pc);
2902#else
2903 pa = p < 0 ? -p : p;
2904 pb = pc < 0 ? -pc : pc;
2905 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
2906#endif
2907 p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
2908#else /* SLOW_PAETH */
2909 p = a + b - c;
2910 pa = abs(p - a);
2911 pb = abs(p - b);
2912 pc = abs(p - c);
2913
2914 if (pa <= pb && pa <= pc)
2915 p = a;
2916
2917 else if (pb <= pc)
2918 p = b;
2919
2920 else
2921 p = c;
2922#endif /* SLOW_PAETH */
2923
2924 v = *dp++ = (png_byte)((int)*rp++ - p);
2925
2926 sum += (v < 128) ? v : 256 - v;
2927
2928 if (sum > lmins) /* We are already worse, don't continue. */
2929 break;
2930 }
2931
2932#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2933 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2934 {
2935 int j;
2936 png_uint_32 sumhi, sumlo;
2937 sumlo = sum & PNG_LOMASK;
2938 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2939
2940 for (j = 0; j < num_p_filters; j++)
2941 {
2942 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
2943 {
2944 sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2945 PNG_WEIGHT_SHIFT;
2946
2947 sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2948 PNG_WEIGHT_SHIFT;
2949 }
2950 }
2951
2952 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2953 PNG_COST_SHIFT;
2954
2955 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2956 PNG_COST_SHIFT;
2957
2958 if (sumhi > PNG_HIMASK)
2959 sum = PNG_MAXSUM;
2960
2961 else
2962 sum = (sumhi << PNG_HISHIFT) + sumlo;
2963 }
2964#endif
2965
2966 if (sum < mins)
2967 {
2968 best_row = png_ptr->paeth_row;
2969 }
2970 }
2971#endif /* WRITE_FILTER */
2972
2973 /* Do the actual writing of the filtered row data from the chosen filter. */
2974 png_write_filtered_row(png_ptr, best_row, row_info->rowbytes+1);
2975
2976#ifdef PNG_WRITE_FILTER_SUPPORTED
2977#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2978 /* Save the type of filter we picked this time for future calculations */
2979 if (png_ptr->num_prev_filters > 0)
2980 {
2981 int j;
2982
2983 for (j = 1; j < num_p_filters; j++)
2984 {
2985 png_ptr->prev_filters[j] = png_ptr->prev_filters[j - 1];
2986 }
2987
2988 png_ptr->prev_filters[j] = best_row[0];
2989 }
2990#endif
2991#endif /* WRITE_FILTER */
2992}
2993
2994
2995/* Do the actual writing of a previously filtered row. */
2996static void
2997png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row,
2998 png_size_t full_row_length/*includes filter byte*/)
2999{
3000 png_debug(1, "in png_write_filtered_row");
3001
3002 png_debug1(2, "filter = %d", filtered_row[0]);
3003
3004 png_compress_IDAT(png_ptr, filtered_row, full_row_length, Z_NO_FLUSH);
3005
3006#ifdef PNG_WRITE_FILTER_SUPPORTED
3007 /* Swap the current and previous rows */
3008 if (png_ptr->prev_row != NULL)
3009 {
3010 png_bytep tptr;
3011
3012 tptr = png_ptr->prev_row;
3013 png_ptr->prev_row = png_ptr->row_buf;
3014 png_ptr->row_buf = tptr;
3015 }
3016#endif /* WRITE_FILTER */
3017
3018 /* Finish row - updates counters and flushes zlib if last row */
3019 png_write_finish_row(png_ptr);
3020
3021#ifdef PNG_WRITE_FLUSH_SUPPORTED
3022 png_ptr->flush_rows++;
3023
3024 if (png_ptr->flush_dist > 0 &&
3025 png_ptr->flush_rows >= png_ptr->flush_dist)
3026 {
3027 png_write_flush(png_ptr);
3028 }
3029#endif /* WRITE_FLUSH */
3030}
3031#endif /* WRITE */