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

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