1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation. Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 */
24
25 /* pngwutil.c - utilities to write a PNG file
26 *
27 * This file is available under and governed by the GNU General Public
28 * License version 2 only, as published by the Free Software Foundation.
29 * However, the following notice accompanied the original version of this
30 * file and, per its terms, should not be removed:
31 *
32 * Last changed in libpng 1.6.22 [May 26, 2016]
33 * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
34 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
35 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
36 *
37 * This code is released under the libpng license.
38 * For conditions of distribution and use, see the disclaimer
39 * and license in png.h
40 */
41
42 #include "pngpriv.h"
43
44 #ifdef PNG_WRITE_SUPPORTED
45
46 #ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
47 /* Place a 32-bit number into a buffer in PNG byte order. We work
48 * with unsigned numbers for convenience, although one supported
49 * ancillary chunk uses signed (two's complement) numbers.
50 */
51 void PNGAPI
52 png_save_uint_32(png_bytep buf, png_uint_32 i)
53 {
54 buf[0] = (png_byte)((i >> 24) & 0xffU);
55 buf[1] = (png_byte)((i >> 16) & 0xffU);
56 buf[2] = (png_byte)((i >> 8) & 0xffU);
57 buf[3] = (png_byte)( i & 0xffU);
58 }
59
60 /* Place a 16-bit number into a buffer in PNG byte order.
61 * The parameter is declared unsigned int, not png_uint_16,
62 * just to avoid potential problems on pre-ANSI C compilers.
63 */
64 void PNGAPI
65 png_save_uint_16(png_bytep buf, unsigned int i)
66 {
67 buf[0] = (png_byte)((i >> 8) & 0xffU);
68 buf[1] = (png_byte)( i & 0xffU);
69 }
70 #endif
71
72 /* Simple function to write the signature. If we have already written
73 * the magic bytes of the signature, or more likely, the PNG stream is
74 * being embedded into another stream and doesn't need its own signature,
75 * we should call png_set_sig_bytes() to tell libpng how many of the
76 * bytes have already been written.
77 */
78 void PNGAPI
79 png_write_sig(png_structrp png_ptr)
80 {
81 png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
82
83 #ifdef PNG_IO_STATE_SUPPORTED
84 /* Inform the I/O callback that the signature is being written */
85 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_SIGNATURE;
86 #endif
87
88 /* Write the rest of the 8 byte signature */
89 png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes],
90 (png_size_t)(8 - png_ptr->sig_bytes));
91
92 if (png_ptr->sig_bytes < 3)
93 png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
94 }
95
96 /* Write the start of a PNG chunk. The type is the chunk type.
97 * The total_length is the sum of the lengths of all the data you will be
98 * passing in png_write_chunk_data().
99 */
100 static void
101 png_write_chunk_header(png_structrp png_ptr, png_uint_32 chunk_name,
102 png_uint_32 length)
103 {
104 png_byte buf[8];
105
106 #if defined(PNG_DEBUG) && (PNG_DEBUG > 0)
107 PNG_CSTRING_FROM_CHUNK(buf, chunk_name);
108 png_debug2(0, "Writing %s chunk, length = %lu", buf, (unsigned long)length);
109 #endif
110
111 if (png_ptr == NULL)
112 return;
113
114 #ifdef PNG_IO_STATE_SUPPORTED
115 /* Inform the I/O callback that the chunk header is being written.
116 * PNG_IO_CHUNK_HDR requires a single I/O call.
117 */
118 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_HDR;
119 #endif
120
121 /* Write the length and the chunk name */
122 png_save_uint_32(buf, length);
123 png_save_uint_32(buf + 4, chunk_name);
124 png_write_data(png_ptr, buf, 8);
125
126 /* Put the chunk name into png_ptr->chunk_name */
127 png_ptr->chunk_name = chunk_name;
128
129 /* Reset the crc and run it over the chunk name */
130 png_reset_crc(png_ptr);
131
132 png_calculate_crc(png_ptr, buf + 4, 4);
133
134 #ifdef PNG_IO_STATE_SUPPORTED
135 /* Inform the I/O callback that chunk data will (possibly) be written.
136 * PNG_IO_CHUNK_DATA does NOT require a specific number of I/O calls.
137 */
138 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_DATA;
139 #endif
140 }
141
142 void PNGAPI
143 png_write_chunk_start(png_structrp png_ptr, png_const_bytep chunk_string,
144 png_uint_32 length)
145 {
146 png_write_chunk_header(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), length);
147 }
148
149 /* Write the data of a PNG chunk started with png_write_chunk_header().
150 * Note that multiple calls to this function are allowed, and that the
151 * sum of the lengths from these calls *must* add up to the total_length
152 * given to png_write_chunk_header().
153 */
154 void PNGAPI
155 png_write_chunk_data(png_structrp png_ptr, png_const_bytep data,
156 png_size_t length)
157 {
158 /* Write the data, and run the CRC over it */
159 if (png_ptr == NULL)
160 return;
161
162 if (data != NULL && length > 0)
163 {
164 png_write_data(png_ptr, data, length);
165
166 /* Update the CRC after writing the data,
167 * in case the user I/O routine alters it.
168 */
169 png_calculate_crc(png_ptr, data, length);
170 }
171 }
172
173 /* Finish a chunk started with png_write_chunk_header(). */
174 void PNGAPI
175 png_write_chunk_end(png_structrp png_ptr)
176 {
177 png_byte buf[4];
178
179 if (png_ptr == NULL) return;
180
181 #ifdef PNG_IO_STATE_SUPPORTED
182 /* Inform the I/O callback that the chunk CRC is being written.
183 * PNG_IO_CHUNK_CRC requires a single I/O function call.
184 */
185 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_CRC;
186 #endif
187
188 /* Write the crc in a single operation */
189 png_save_uint_32(buf, png_ptr->crc);
190
191 png_write_data(png_ptr, buf, (png_size_t)4);
192 }
193
194 /* Write a PNG chunk all at once. The type is an array of ASCII characters
195 * representing the chunk name. The array must be at least 4 bytes in
196 * length, and does not need to be null terminated. To be safe, pass the
197 * pre-defined chunk names here, and if you need a new one, define it
198 * where the others are defined. The length is the length of the data.
199 * All the data must be present. If that is not possible, use the
200 * png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end()
201 * functions instead.
202 */
203 static void
204 png_write_complete_chunk(png_structrp png_ptr, png_uint_32 chunk_name,
205 png_const_bytep data, png_size_t length)
206 {
207 if (png_ptr == NULL)
208 return;
209
210 /* On 64-bit architectures 'length' may not fit in a png_uint_32. */
211 if (length > PNG_UINT_31_MAX)
212 png_error(png_ptr, "length exceeds PNG maximum");
213
214 png_write_chunk_header(png_ptr, chunk_name, (png_uint_32)length);
215 png_write_chunk_data(png_ptr, data, length);
216 png_write_chunk_end(png_ptr);
217 }
218
219 /* This is the API that calls the internal function above. */
220 void PNGAPI
221 png_write_chunk(png_structrp png_ptr, png_const_bytep chunk_string,
222 png_const_bytep data, png_size_t length)
223 {
224 png_write_complete_chunk(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), data,
225 length);
226 }
227
228 /* This is used below to find the size of an image to pass to png_deflate_claim,
229 * so it only needs to be accurate if the size is less than 16384 bytes (the
230 * point at which a lower LZ window size can be used.)
231 */
232 static png_alloc_size_t
233 png_image_size(png_structrp png_ptr)
234 {
235 /* Only return sizes up to the maximum of a png_uint_32; do this by limiting
236 * the width and height used to 15 bits.
237 */
238 png_uint_32 h = png_ptr->height;
239
240 if (png_ptr->rowbytes < 32768 && h < 32768)
241 {
242 if (png_ptr->interlaced != 0)
243 {
244 /* Interlacing makes the image larger because of the replication of
245 * both the filter byte and the padding to a byte boundary.
246 */
247 png_uint_32 w = png_ptr->width;
248 unsigned int pd = png_ptr->pixel_depth;
249 png_alloc_size_t cb_base;
250 int pass;
251
252 for (cb_base=0, pass=0; pass<=6; ++pass)
253 {
254 png_uint_32 pw = PNG_PASS_COLS(w, pass);
255
256 if (pw > 0)
257 cb_base += (PNG_ROWBYTES(pd, pw)+1) * PNG_PASS_ROWS(h, pass);
258 }
259
260 return cb_base;
261 }
262
263 else
264 return (png_ptr->rowbytes+1) * h;
265 }
266
267 else
268 return 0xffffffffU;
269 }
270
271 #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
272 /* This is the code to hack the first two bytes of the deflate stream (the
273 * deflate header) to correct the windowBits value to match the actual data
274 * size. Note that the second argument is the *uncompressed* size but the
275 * first argument is the *compressed* data (and it must be deflate
276 * compressed.)
277 */
278 static void
279 optimize_cmf(png_bytep data, png_alloc_size_t data_size)
280 {
281 /* Optimize the CMF field in the zlib stream. The resultant zlib stream is
282 * still compliant to the stream specification.
283 */
284 if (data_size <= 16384) /* else windowBits must be 15 */
285 {
286 unsigned int z_cmf = data[0]; /* zlib compression method and flags */
287
288 if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
289 {
290 unsigned int z_cinfo;
291 unsigned int half_z_window_size;
292
293 z_cinfo = z_cmf >> 4;
294 half_z_window_size = 1U << (z_cinfo + 7);
295
296 if (data_size <= half_z_window_size) /* else no change */
297 {
298 unsigned int tmp;
299
300 do
301 {
302 half_z_window_size >>= 1;
303 --z_cinfo;
304 }
305 while (z_cinfo > 0 && data_size <= half_z_window_size);
306
307 z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
308
309 data[0] = (png_byte)z_cmf;
310 tmp = data[1] & 0xe0;
311 tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
312 data[1] = (png_byte)tmp;
313 }
314 }
315 }
316 }
317 #endif /* WRITE_OPTIMIZE_CMF */
318
319 /* Initialize the compressor for the appropriate type of compression. */
320 static int
321 png_deflate_claim(png_structrp png_ptr, png_uint_32 owner,
322 png_alloc_size_t data_size)
323 {
324 if (png_ptr->zowner != 0)
325 {
326 #if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_ERROR_TEXT_SUPPORTED)
327 char msg[64];
328
329 PNG_STRING_FROM_CHUNK(msg, owner);
330 msg[4] = ':';
331 msg[5] = ' ';
332 PNG_STRING_FROM_CHUNK(msg+6, png_ptr->zowner);
333 /* So the message that results is "<chunk> using zstream"; this is an
334 * internal error, but is very useful for debugging. i18n requirements
335 * are minimal.
336 */
337 (void)png_safecat(msg, (sizeof msg), 10, " using zstream");
338 #endif
339 #if PNG_RELEASE_BUILD
340 png_warning(png_ptr, msg);
341
342 /* Attempt sane error recovery */
343 if (png_ptr->zowner == png_IDAT) /* don't steal from IDAT */
344 {
345 png_ptr->zstream.msg = PNGZ_MSG_CAST("in use by IDAT");
346 return Z_STREAM_ERROR;
347 }
348
349 png_ptr->zowner = 0;
350 #else
351 png_error(png_ptr, msg);
352 #endif
353 }
354
355 {
356 int level = png_ptr->zlib_level;
357 int method = png_ptr->zlib_method;
358 int windowBits = png_ptr->zlib_window_bits;
359 int memLevel = png_ptr->zlib_mem_level;
360 int strategy; /* set below */
361 int ret; /* zlib return code */
362
363 if (owner == png_IDAT)
364 {
365 if ((png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY) != 0)
366 strategy = png_ptr->zlib_strategy;
367
368 else if (png_ptr->do_filter != PNG_FILTER_NONE)
369 strategy = PNG_Z_DEFAULT_STRATEGY;
370
371 else
372 strategy = PNG_Z_DEFAULT_NOFILTER_STRATEGY;
373 }
374
375 else
376 {
377 #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
378 level = png_ptr->zlib_text_level;
379 method = png_ptr->zlib_text_method;
380 windowBits = png_ptr->zlib_text_window_bits;
381 memLevel = png_ptr->zlib_text_mem_level;
382 strategy = png_ptr->zlib_text_strategy;
383 #else
384 /* If customization is not supported the values all come from the
385 * IDAT values except for the strategy, which is fixed to the
386 * default. (This is the pre-1.6.0 behavior too, although it was
387 * implemented in a very different way.)
388 */
389 strategy = Z_DEFAULT_STRATEGY;
390 #endif
391 }
392
393 /* Adjust 'windowBits' down if larger than 'data_size'; to stop this
394 * happening just pass 32768 as the data_size parameter. Notice that zlib
395 * requires an extra 262 bytes in the window in addition to the data to be
396 * able to see the whole of the data, so if data_size+262 takes us to the
397 * next windowBits size we need to fix up the value later. (Because even
398 * though deflate needs the extra window, inflate does not!)
399 */
400 if (data_size <= 16384)
401 {
402 /* IMPLEMENTATION NOTE: this 'half_window_size' stuff is only here to
403 * work round a Microsoft Visual C misbehavior which, contrary to C-90,
404 * widens the result of the following shift to 64-bits if (and,
405 * apparently, only if) it is used in a test.
406 */
407 unsigned int half_window_size = 1U << (windowBits-1);
408
409 while (data_size + 262 <= half_window_size)
410 {
411 half_window_size >>= 1;
412 --windowBits;
413 }
414 }
415
416 /* Check against the previous initialized values, if any. */
417 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0 &&
418 (png_ptr->zlib_set_level != level ||
419 png_ptr->zlib_set_method != method ||
420 png_ptr->zlib_set_window_bits != windowBits ||
421 png_ptr->zlib_set_mem_level != memLevel ||
422 png_ptr->zlib_set_strategy != strategy))
423 {
424 if (deflateEnd(&png_ptr->zstream) != Z_OK)
425 png_warning(png_ptr, "deflateEnd failed (ignored)");
426
427 png_ptr->flags &= ~PNG_FLAG_ZSTREAM_INITIALIZED;
428 }
429
430 /* For safety clear out the input and output pointers (currently zlib
431 * doesn't use them on Init, but it might in the future).
432 */
433 png_ptr->zstream.next_in = NULL;
434 png_ptr->zstream.avail_in = 0;
435 png_ptr->zstream.next_out = NULL;
436 png_ptr->zstream.avail_out = 0;
437
438 /* Now initialize if required, setting the new parameters, otherwise just
439 * to a simple reset to the previous parameters.
440 */
441 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
442 ret = deflateReset(&png_ptr->zstream);
443
444 else
445 {
446 ret = deflateInit2(&png_ptr->zstream, level, method, windowBits,
447 memLevel, strategy);
448
449 if (ret == Z_OK)
450 png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
451 }
452
453 /* The return code is from either deflateReset or deflateInit2; they have
454 * pretty much the same set of error codes.
455 */
456 if (ret == Z_OK)
457 png_ptr->zowner = owner;
458
459 else
460 png_zstream_error(png_ptr, ret);
461
462 return ret;
463 }
464 }
465
466 /* Clean up (or trim) a linked list of compression buffers. */
467 void /* PRIVATE */
468 png_free_buffer_list(png_structrp png_ptr, png_compression_bufferp *listp)
469 {
470 png_compression_bufferp list = *listp;
471
472 if (list != NULL)
473 {
474 *listp = NULL;
475
476 do
477 {
478 png_compression_bufferp next = list->next;
479
480 png_free(png_ptr, list);
481 list = next;
482 }
483 while (list != NULL);
484 }
485 }
486
487 #ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
488 /* This pair of functions encapsulates the operation of (a) compressing a
489 * text string, and (b) issuing it later as a series of chunk data writes.
490 * The compression_state structure is shared context for these functions
491 * set up by the caller to allow access to the relevant local variables.
492 *
493 * compression_buffer (new in 1.6.0) is just a linked list of zbuffer_size
494 * temporary buffers. From 1.6.0 it is retained in png_struct so that it will
495 * be correctly freed in the event of a write error (previous implementations
496 * just leaked memory.)
497 */
498 typedef struct
499 {
500 png_const_bytep input; /* The uncompressed input data */
501 png_alloc_size_t input_len; /* Its length */
502 png_uint_32 output_len; /* Final compressed length */
503 png_byte output[1024]; /* First block of output */
504 } compression_state;
505
506 static void
507 png_text_compress_init(compression_state *comp, png_const_bytep input,
508 png_alloc_size_t input_len)
509 {
510 comp->input = input;
511 comp->input_len = input_len;
512 comp->output_len = 0;
513 }
514
515 /* Compress the data in the compression state input */
516 static int
517 png_text_compress(png_structrp png_ptr, png_uint_32 chunk_name,
518 compression_state *comp, png_uint_32 prefix_len)
519 {
520 int ret;
521
522 /* To find the length of the output it is necessary to first compress the
523 * input. The result is buffered rather than using the two-pass algorithm
524 * that is used on the inflate side; deflate is assumed to be slower and a
525 * PNG writer is assumed to have more memory available than a PNG reader.
526 *
527 * IMPLEMENTATION NOTE: the zlib API deflateBound() can be used to find an
528 * upper limit on the output size, but it is always bigger than the input
529 * size so it is likely to be more efficient to use this linked-list
530 * approach.
531 */
532 ret = png_deflate_claim(png_ptr, chunk_name, comp->input_len);
533
534 if (ret != Z_OK)
535 return ret;
536
537 /* Set up the compression buffers, we need a loop here to avoid overflowing a
538 * uInt. Use ZLIB_IO_MAX to limit the input. The output is always limited
539 * by the output buffer size, so there is no need to check that. Since this
540 * is ANSI-C we know that an 'int', hence a uInt, is always at least 16 bits
541 * in size.
542 */
543 {
544 png_compression_bufferp *end = &png_ptr->zbuffer_list;
545 png_alloc_size_t input_len = comp->input_len; /* may be zero! */
546 png_uint_32 output_len;
547
548 /* zlib updates these for us: */
549 png_ptr->zstream.next_in = PNGZ_INPUT_CAST(comp->input);
550 png_ptr->zstream.avail_in = 0; /* Set below */
551 png_ptr->zstream.next_out = comp->output;
552 png_ptr->zstream.avail_out = (sizeof comp->output);
553
554 output_len = png_ptr->zstream.avail_out;
555
556 do
557 {
558 uInt avail_in = ZLIB_IO_MAX;
559
560 if (avail_in > input_len)
561 avail_in = (uInt)input_len;
562
563 input_len -= avail_in;
564
565 png_ptr->zstream.avail_in = avail_in;
566
567 if (png_ptr->zstream.avail_out == 0)
568 {
569 png_compression_buffer *next;
570
571 /* Chunk data is limited to 2^31 bytes in length, so the prefix
572 * length must be counted here.
573 */
574 if (output_len + prefix_len > PNG_UINT_31_MAX)
575 {
576 ret = Z_MEM_ERROR;
577 break;
578 }
579
580 /* Need a new (malloc'ed) buffer, but there may be one present
581 * already.
582 */
583 next = *end;
584 if (next == NULL)
585 {
586 next = png_voidcast(png_compression_bufferp, png_malloc_base
587 (png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr)));
588
589 if (next == NULL)
590 {
591 ret = Z_MEM_ERROR;
592 break;
593 }
594
595 /* Link in this buffer (so that it will be freed later) */
596 next->next = NULL;
597 *end = next;
598 }
599
600 png_ptr->zstream.next_out = next->output;
601 png_ptr->zstream.avail_out = png_ptr->zbuffer_size;
602 output_len += png_ptr->zstream.avail_out;
603
604 /* Move 'end' to the next buffer pointer. */
605 end = &next->next;
606 }
607
608 /* Compress the data */
609 ret = deflate(&png_ptr->zstream,
610 input_len > 0 ? Z_NO_FLUSH : Z_FINISH);
611
612 /* Claw back input data that was not consumed (because avail_in is
613 * reset above every time round the loop).
614 */
615 input_len += png_ptr->zstream.avail_in;
616 png_ptr->zstream.avail_in = 0; /* safety */
617 }
618 while (ret == Z_OK);
619
620 /* There may be some space left in the last output buffer. This needs to
621 * be subtracted from output_len.
622 */
623 output_len -= png_ptr->zstream.avail_out;
624 png_ptr->zstream.avail_out = 0; /* safety */
625 comp->output_len = output_len;
626
627 /* Now double check the output length, put in a custom message if it is
628 * too long. Otherwise ensure the z_stream::msg pointer is set to
629 * something.
630 */
631 if (output_len + prefix_len >= PNG_UINT_31_MAX)
632 {
633 png_ptr->zstream.msg = PNGZ_MSG_CAST("compressed data too long");
634 ret = Z_MEM_ERROR;
635 }
636
637 else
638 png_zstream_error(png_ptr, ret);
639
640 /* Reset zlib for another zTXt/iTXt or image data */
641 png_ptr->zowner = 0;
642
643 /* The only success case is Z_STREAM_END, input_len must be 0; if not this
644 * is an internal error.
645 */
646 if (ret == Z_STREAM_END && input_len == 0)
647 {
648 #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
649 /* Fix up the deflate header, if required */
650 optimize_cmf(comp->output, comp->input_len);
651 #endif
652 /* But Z_OK is returned, not Z_STREAM_END; this allows the claim
653 * function above to return Z_STREAM_END on an error (though it never
654 * does in the current versions of zlib.)
655 */
656 return Z_OK;
657 }
658
659 else
660 return ret;
661 }
662 }
663
664 /* Ship the compressed text out via chunk writes */
665 static void
666 png_write_compressed_data_out(png_structrp png_ptr, compression_state *comp)
667 {
668 png_uint_32 output_len = comp->output_len;
669 png_const_bytep output = comp->output;
670 png_uint_32 avail = (sizeof comp->output);
671 png_compression_buffer *next = png_ptr->zbuffer_list;
672
673 for (;;)
674 {
675 if (avail > output_len)
676 avail = output_len;
677
678 png_write_chunk_data(png_ptr, output, avail);
679
680 output_len -= avail;
681
682 if (output_len == 0 || next == NULL)
683 break;
684
685 avail = png_ptr->zbuffer_size;
686 output = next->output;
687 next = next->next;
688 }
689
690 /* This is an internal error; 'next' must have been NULL! */
691 if (output_len > 0)
692 png_error(png_ptr, "error writing ancillary chunked compressed data");
693 }
694 #endif /* WRITE_COMPRESSED_TEXT */
695
696 /* Write the IHDR chunk, and update the png_struct with the necessary
697 * information. Note that the rest of this code depends upon this
698 * information being correct.
699 */
700 void /* PRIVATE */
701 png_write_IHDR(png_structrp png_ptr, png_uint_32 width, png_uint_32 height,
702 int bit_depth, int color_type, int compression_type, int filter_type,
703 int interlace_type)
704 {
705 png_byte buf[13]; /* Buffer to store the IHDR info */
706
707 png_debug(1, "in png_write_IHDR");
708
709 /* Check that we have valid input data from the application info */
710 switch (color_type)
711 {
712 case PNG_COLOR_TYPE_GRAY:
713 switch (bit_depth)
714 {
715 case 1:
716 case 2:
717 case 4:
718 case 8:
719 #ifdef PNG_WRITE_16BIT_SUPPORTED
720 case 16:
721 #endif
722 png_ptr->channels = 1; break;
723
724 default:
725 png_error(png_ptr,
726 "Invalid bit depth for grayscale image");
727 }
728 break;
729
730 case PNG_COLOR_TYPE_RGB:
731 #ifdef PNG_WRITE_16BIT_SUPPORTED
732 if (bit_depth != 8 && bit_depth != 16)
733 #else
734 if (bit_depth != 8)
735 #endif
736 png_error(png_ptr, "Invalid bit depth for RGB image");
737
738 png_ptr->channels = 3;
739 break;
740
741 case PNG_COLOR_TYPE_PALETTE:
742 switch (bit_depth)
743 {
744 case 1:
745 case 2:
746 case 4:
747 case 8:
748 png_ptr->channels = 1;
749 break;
750
751 default:
752 png_error(png_ptr, "Invalid bit depth for paletted image");
753 }
754 break;
755
756 case PNG_COLOR_TYPE_GRAY_ALPHA:
757 if (bit_depth != 8 && bit_depth != 16)
758 png_error(png_ptr, "Invalid bit depth for grayscale+alpha image");
759
760 png_ptr->channels = 2;
761 break;
762
763 case PNG_COLOR_TYPE_RGB_ALPHA:
764 #ifdef PNG_WRITE_16BIT_SUPPORTED
765 if (bit_depth != 8 && bit_depth != 16)
766 #else
767 if (bit_depth != 8)
768 #endif
769 png_error(png_ptr, "Invalid bit depth for RGBA image");
770
771 png_ptr->channels = 4;
772 break;
773
774 default:
775 png_error(png_ptr, "Invalid image color type specified");
776 }
777
778 if (compression_type != PNG_COMPRESSION_TYPE_BASE)
779 {
780 png_warning(png_ptr, "Invalid compression type specified");
781 compression_type = PNG_COMPRESSION_TYPE_BASE;
782 }
783
784 /* Write filter_method 64 (intrapixel differencing) only if
785 * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
786 * 2. Libpng did not write a PNG signature (this filter_method is only
787 * used in PNG datastreams that are embedded in MNG datastreams) and
788 * 3. The application called png_permit_mng_features with a mask that
789 * included PNG_FLAG_MNG_FILTER_64 and
790 * 4. The filter_method is 64 and
791 * 5. The color_type is RGB or RGBA
792 */
793 if (
794 #ifdef PNG_MNG_FEATURES_SUPPORTED
795 !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
796 ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
797 (color_type == PNG_COLOR_TYPE_RGB ||
798 color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&
799 (filter_type == PNG_INTRAPIXEL_DIFFERENCING)) &&
800 #endif
801 filter_type != PNG_FILTER_TYPE_BASE)
802 {
803 png_warning(png_ptr, "Invalid filter type specified");
804 filter_type = PNG_FILTER_TYPE_BASE;
805 }
806
807 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
808 if (interlace_type != PNG_INTERLACE_NONE &&
809 interlace_type != PNG_INTERLACE_ADAM7)
810 {
811 png_warning(png_ptr, "Invalid interlace type specified");
812 interlace_type = PNG_INTERLACE_ADAM7;
813 }
814 #else
815 interlace_type=PNG_INTERLACE_NONE;
816 #endif
817
818 /* Save the relevant information */
819 png_ptr->bit_depth = (png_byte)bit_depth;
820 png_ptr->color_type = (png_byte)color_type;
821 png_ptr->interlaced = (png_byte)interlace_type;
822 #ifdef PNG_MNG_FEATURES_SUPPORTED
823 png_ptr->filter_type = (png_byte)filter_type;
824 #endif
825 png_ptr->compression_type = (png_byte)compression_type;
826 png_ptr->width = width;
827 png_ptr->height = height;
828
829 png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels);
830 png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width);
831 /* Set the usr info, so any transformations can modify it */
832 png_ptr->usr_width = png_ptr->width;
833 png_ptr->usr_bit_depth = png_ptr->bit_depth;
834 png_ptr->usr_channels = png_ptr->channels;
835
836 /* Pack the header information into the buffer */
837 png_save_uint_32(buf, width);
838 png_save_uint_32(buf + 4, height);
839 buf[8] = (png_byte)bit_depth;
840 buf[9] = (png_byte)color_type;
841 buf[10] = (png_byte)compression_type;
842 buf[11] = (png_byte)filter_type;
843 buf[12] = (png_byte)interlace_type;
844
845 /* Write the chunk */
846 png_write_complete_chunk(png_ptr, png_IHDR, buf, (png_size_t)13);
847
848 if ((png_ptr->do_filter) == PNG_NO_FILTERS)
849 {
850 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
851 png_ptr->bit_depth < 8)
852 png_ptr->do_filter = PNG_FILTER_NONE;
853
854 else
855 png_ptr->do_filter = PNG_ALL_FILTERS;
856 }
857
858 png_ptr->mode = PNG_HAVE_IHDR; /* not READY_FOR_ZTXT */
859 }
860
861 /* Write the palette. We are careful not to trust png_color to be in the
862 * correct order for PNG, so people can redefine it to any convenient
863 * structure.
864 */
865 void /* PRIVATE */
866 png_write_PLTE(png_structrp png_ptr, png_const_colorp palette,
867 png_uint_32 num_pal)
868 {
869 png_uint_32 max_palette_length, i;
870 png_const_colorp pal_ptr;
871 png_byte buf[3];
872
873 png_debug(1, "in png_write_PLTE");
874
875 max_palette_length = (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ?
876 (1 << png_ptr->bit_depth) : PNG_MAX_PALETTE_LENGTH;
877
878 if ((
879 #ifdef PNG_MNG_FEATURES_SUPPORTED
880 (png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0 &&
881 #endif
882 num_pal == 0) || num_pal > max_palette_length)
883 {
884 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
885 {
886 png_error(png_ptr, "Invalid number of colors in palette");
887 }
888
889 else
890 {
891 png_warning(png_ptr, "Invalid number of colors in palette");
892 return;
893 }
894 }
895
896 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
897 {
898 png_warning(png_ptr,
899 "Ignoring request to write a PLTE chunk in grayscale PNG");
900
901 return;
902 }
903
904 png_ptr->num_palette = (png_uint_16)num_pal;
905 png_debug1(3, "num_palette = %d", png_ptr->num_palette);
906
907 png_write_chunk_header(png_ptr, png_PLTE, (png_uint_32)(num_pal * 3));
908 #ifdef PNG_POINTER_INDEXING_SUPPORTED
909
910 for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++)
911 {
912 buf[0] = pal_ptr->red;
913 buf[1] = pal_ptr->green;
914 buf[2] = pal_ptr->blue;
915 png_write_chunk_data(png_ptr, buf, (png_size_t)3);
916 }
917
918 #else
919 /* This is a little slower but some buggy compilers need to do this
920 * instead
921 */
922 pal_ptr=palette;
923
924 for (i = 0; i < num_pal; i++)
925 {
926 buf[0] = pal_ptr[i].red;
927 buf[1] = pal_ptr[i].green;
928 buf[2] = pal_ptr[i].blue;
929 png_write_chunk_data(png_ptr, buf, (png_size_t)3);
930 }
931
932 #endif
933 png_write_chunk_end(png_ptr);
934 png_ptr->mode |= PNG_HAVE_PLTE;
935 }
936
937 /* This is similar to png_text_compress, above, except that it does not require
938 * all of the data at once and, instead of buffering the compressed result,
939 * writes it as IDAT chunks. Unlike png_text_compress it *can* png_error out
940 * because it calls the write interface. As a result it does its own error
941 * reporting and does not return an error code. In the event of error it will
942 * just call png_error. The input data length may exceed 32-bits. The 'flush'
943 * parameter is exactly the same as that to deflate, with the following
944 * meanings:
945 *
946 * Z_NO_FLUSH: normal incremental output of compressed data
947 * Z_SYNC_FLUSH: do a SYNC_FLUSH, used by png_write_flush
948 * Z_FINISH: this is the end of the input, do a Z_FINISH and clean up
949 *
950 * The routine manages the acquire and release of the png_ptr->zstream by
951 * checking and (at the end) clearing png_ptr->zowner; it does some sanity
952 * checks on the 'mode' flags while doing this.
953 */
954 void /* PRIVATE */
955 png_compress_IDAT(png_structrp png_ptr, png_const_bytep input,
956 png_alloc_size_t input_len, int flush)
957 {
958 if (png_ptr->zowner != png_IDAT)
959 {
960 /* First time. Ensure we have a temporary buffer for compression and
961 * trim the buffer list if it has more than one entry to free memory.
962 * If 'WRITE_COMPRESSED_TEXT' is not set the list will never have been
963 * created at this point, but the check here is quick and safe.
964 */
965 if (png_ptr->zbuffer_list == NULL)
966 {
967 png_ptr->zbuffer_list = png_voidcast(png_compression_bufferp,
968 png_malloc(png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr)));
969 png_ptr->zbuffer_list->next = NULL;
970 }
971
972 else
973 png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list->next);
974
975 /* It is a terminal error if we can't claim the zstream. */
976 if (png_deflate_claim(png_ptr, png_IDAT, png_image_size(png_ptr)) != Z_OK)
977 png_error(png_ptr, png_ptr->zstream.msg);
978
979 /* The output state is maintained in png_ptr->zstream, so it must be
980 * initialized here after the claim.
981 */
982 png_ptr->zstream.next_out = png_ptr->zbuffer_list->output;
983 png_ptr->zstream.avail_out = png_ptr->zbuffer_size;
984 }
985
986 /* Now loop reading and writing until all the input is consumed or an error
987 * terminates the operation. The _out values are maintained across calls to
988 * this function, but the input must be reset each time.
989 */
990 png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
991 png_ptr->zstream.avail_in = 0; /* set below */
992 for (;;)
993 {
994 int ret;
995
996 /* INPUT: from the row data */
997 uInt avail = ZLIB_IO_MAX;
998
999 if (avail > input_len)
1000 avail = (uInt)input_len; /* safe because of the check */
1001
1002 png_ptr->zstream.avail_in = avail;
1003 input_len -= avail;
1004
1005 ret = deflate(&png_ptr->zstream, input_len > 0 ? Z_NO_FLUSH : flush);
1006
1007 /* Include as-yet unconsumed input */
1008 input_len += png_ptr->zstream.avail_in;
1009 png_ptr->zstream.avail_in = 0;
1010
1011 /* OUTPUT: write complete IDAT chunks when avail_out drops to zero. Note
1012 * that these two zstream fields are preserved across the calls, therefore
1013 * there is no need to set these up on entry to the loop.
1014 */
1015 if (png_ptr->zstream.avail_out == 0)
1016 {
1017 png_bytep data = png_ptr->zbuffer_list->output;
1018 uInt size = png_ptr->zbuffer_size;
1019
1020 /* Write an IDAT containing the data then reset the buffer. The
1021 * first IDAT may need deflate header optimization.
1022 */
1023 #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
1024 if ((png_ptr->mode & PNG_HAVE_IDAT) == 0 &&
1025 png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
1026 optimize_cmf(data, png_image_size(png_ptr));
1027 #endif
1028
1029 png_write_complete_chunk(png_ptr, png_IDAT, data, size);
1030 png_ptr->mode |= PNG_HAVE_IDAT;
1031
1032 png_ptr->zstream.next_out = data;
1033 png_ptr->zstream.avail_out = size;
1034
1035 /* For SYNC_FLUSH or FINISH it is essential to keep calling zlib with
1036 * the same flush parameter until it has finished output, for NO_FLUSH
1037 * it doesn't matter.
1038 */
1039 if (ret == Z_OK && flush != Z_NO_FLUSH)
1040 continue;
1041 }
1042
1043 /* The order of these checks doesn't matter much; it just affects which
1044 * possible error might be detected if multiple things go wrong at once.
1045 */
1046 if (ret == Z_OK) /* most likely return code! */
1047 {
1048 /* If all the input has been consumed then just return. If Z_FINISH
1049 * was used as the flush parameter something has gone wrong if we get
1050 * here.
1051 */
1052 if (input_len == 0)
1053 {
1054 if (flush == Z_FINISH)
1055 png_error(png_ptr, "Z_OK on Z_FINISH with output space");
1056
1057 return;
1058 }
1059 }
1060
1061 else if (ret == Z_STREAM_END && flush == Z_FINISH)
1062 {
1063 /* This is the end of the IDAT data; any pending output must be
1064 * flushed. For small PNG files we may still be at the beginning.
1065 */
1066 png_bytep data = png_ptr->zbuffer_list->output;
1067 uInt size = png_ptr->zbuffer_size - png_ptr->zstream.avail_out;
1068
1069 #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
1070 if ((png_ptr->mode & PNG_HAVE_IDAT) == 0 &&
1071 png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
1072 optimize_cmf(data, png_image_size(png_ptr));
1073 #endif
1074
1075 png_write_complete_chunk(png_ptr, png_IDAT, data, size);
1076 png_ptr->zstream.avail_out = 0;
1077 png_ptr->zstream.next_out = NULL;
1078 png_ptr->mode |= PNG_HAVE_IDAT | PNG_AFTER_IDAT;
1079
1080 png_ptr->zowner = 0; /* Release the stream */
1081 return;
1082 }
1083
1084 else
1085 {
1086 /* This is an error condition. */
1087 png_zstream_error(png_ptr, ret);
1088 png_error(png_ptr, png_ptr->zstream.msg);
1089 }
1090 }
1091 }
1092
1093 /* Write an IEND chunk */
1094 void /* PRIVATE */
1095 png_write_IEND(png_structrp png_ptr)
1096 {
1097 png_debug(1, "in png_write_IEND");
1098
1099 png_write_complete_chunk(png_ptr, png_IEND, NULL, (png_size_t)0);
1100 png_ptr->mode |= PNG_HAVE_IEND;
1101 }
1102
1103 #ifdef PNG_WRITE_gAMA_SUPPORTED
1104 /* Write a gAMA chunk */
1105 void /* PRIVATE */
1106 png_write_gAMA_fixed(png_structrp png_ptr, png_fixed_point file_gamma)
1107 {
1108 png_byte buf[4];
1109
1110 png_debug(1, "in png_write_gAMA");
1111
1112 /* file_gamma is saved in 1/100,000ths */
1113 png_save_uint_32(buf, (png_uint_32)file_gamma);
1114 png_write_complete_chunk(png_ptr, png_gAMA, buf, (png_size_t)4);
1115 }
1116 #endif
1117
1118 #ifdef PNG_WRITE_sRGB_SUPPORTED
1119 /* Write a sRGB chunk */
1120 void /* PRIVATE */
1121 png_write_sRGB(png_structrp png_ptr, int srgb_intent)
1122 {
1123 png_byte buf[1];
1124
1125 png_debug(1, "in png_write_sRGB");
1126
1127 if (srgb_intent >= PNG_sRGB_INTENT_LAST)
1128 png_warning(png_ptr,
1129 "Invalid sRGB rendering intent specified");
1130
1131 buf[0]=(png_byte)srgb_intent;
1132 png_write_complete_chunk(png_ptr, png_sRGB, buf, (png_size_t)1);
1133 }
1134 #endif
1135
1136 #ifdef PNG_WRITE_iCCP_SUPPORTED
1137 /* Write an iCCP chunk */
1138 void /* PRIVATE */
1139 png_write_iCCP(png_structrp png_ptr, png_const_charp name,
1140 png_const_bytep profile)
1141 {
1142 png_uint_32 name_len;
1143 png_uint_32 profile_len;
1144 png_byte new_name[81]; /* 1 byte for the compression byte */
1145 compression_state comp;
1146 png_uint_32 temp;
1147
1148 png_debug(1, "in png_write_iCCP");
1149
1150 /* These are all internal problems: the profile should have been checked
1151 * before when it was stored.
1152 */
1153 if (profile == NULL)
1154 png_error(png_ptr, "No profile for iCCP chunk"); /* internal error */
1155
1156 profile_len = png_get_uint_32(profile);
1157
1158 if (profile_len < 132)
1159 png_error(png_ptr, "ICC profile too short");
1160
1161 temp = (png_uint_32) (*(profile+8));
1162 if (temp > 3 && (profile_len & 0x03))
1163 png_error(png_ptr, "ICC profile length invalid (not a multiple of 4)");
1164
1165 {
1166 png_uint_32 embedded_profile_len = png_get_uint_32(profile);
1167
1168 if (profile_len != embedded_profile_len)
1169 png_error(png_ptr, "Profile length does not match profile");
1170 }
1171
1172 name_len = png_check_keyword(png_ptr, name, new_name);
1173
1174 if (name_len == 0)
1175 png_error(png_ptr, "iCCP: invalid keyword");
1176
1177 new_name[++name_len] = PNG_COMPRESSION_TYPE_BASE;
1178
1179 /* Make sure we include the NULL after the name and the compression type */
1180 ++name_len;
1181
1182 png_text_compress_init(&comp, profile, profile_len);
1183
1184 /* Allow for keyword terminator and compression byte */
1185 if (png_text_compress(png_ptr, png_iCCP, &comp, name_len) != Z_OK)
1186 png_error(png_ptr, png_ptr->zstream.msg);
1187
1188 png_write_chunk_header(png_ptr, png_iCCP, name_len + comp.output_len);
1189
1190 png_write_chunk_data(png_ptr, new_name, name_len);
1191
1192 png_write_compressed_data_out(png_ptr, &comp);
1193
1194 png_write_chunk_end(png_ptr);
1195 }
1196 #endif
1197
1198 #ifdef PNG_WRITE_sPLT_SUPPORTED
1199 /* Write a sPLT chunk */
1200 void /* PRIVATE */
1201 png_write_sPLT(png_structrp png_ptr, png_const_sPLT_tp spalette)
1202 {
1203 png_uint_32 name_len;
1204 png_byte new_name[80];
1205 png_byte entrybuf[10];
1206 png_size_t entry_size = (spalette->depth == 8 ? 6 : 10);
1207 png_size_t palette_size = entry_size * spalette->nentries;
1208 png_sPLT_entryp ep;
1209 #ifndef PNG_POINTER_INDEXING_SUPPORTED
1210 int i;
1211 #endif
1212
1213 png_debug(1, "in png_write_sPLT");
1214
1215 name_len = png_check_keyword(png_ptr, spalette->name, new_name);
1216
1217 if (name_len == 0)
1218 png_error(png_ptr, "sPLT: invalid keyword");
1219
1220 /* Make sure we include the NULL after the name */
1221 png_write_chunk_header(png_ptr, png_sPLT,
1222 (png_uint_32)(name_len + 2 + palette_size));
1223
1224 png_write_chunk_data(png_ptr, (png_bytep)new_name,
1225 (png_size_t)(name_len + 1));
1226
1227 png_write_chunk_data(png_ptr, &spalette->depth, (png_size_t)1);
1228
1229 /* Loop through each palette entry, writing appropriately */
1230 #ifdef PNG_POINTER_INDEXING_SUPPORTED
1231 for (ep = spalette->entries; ep<spalette->entries + spalette->nentries; ep++)
1232 {
1233 if (spalette->depth == 8)
1234 {
1235 entrybuf[0] = (png_byte)ep->red;
1236 entrybuf[1] = (png_byte)ep->green;
1237 entrybuf[2] = (png_byte)ep->blue;
1238 entrybuf[3] = (png_byte)ep->alpha;
1239 png_save_uint_16(entrybuf + 4, ep->frequency);
1240 }
1241
1242 else
1243 {
1244 png_save_uint_16(entrybuf + 0, ep->red);
1245 png_save_uint_16(entrybuf + 2, ep->green);
1246 png_save_uint_16(entrybuf + 4, ep->blue);
1247 png_save_uint_16(entrybuf + 6, ep->alpha);
1248 png_save_uint_16(entrybuf + 8, ep->frequency);
1249 }
1250
1251 png_write_chunk_data(png_ptr, entrybuf, entry_size);
1252 }
1253 #else
1254 ep=spalette->entries;
1255 for (i = 0; i>spalette->nentries; i++)
1256 {
1257 if (spalette->depth == 8)
1258 {
1259 entrybuf[0] = (png_byte)ep[i].red;
1260 entrybuf[1] = (png_byte)ep[i].green;
1261 entrybuf[2] = (png_byte)ep[i].blue;
1262 entrybuf[3] = (png_byte)ep[i].alpha;
1263 png_save_uint_16(entrybuf + 4, ep[i].frequency);
1264 }
1265
1266 else
1267 {
1268 png_save_uint_16(entrybuf + 0, ep[i].red);
1269 png_save_uint_16(entrybuf + 2, ep[i].green);
1270 png_save_uint_16(entrybuf + 4, ep[i].blue);
1271 png_save_uint_16(entrybuf + 6, ep[i].alpha);
1272 png_save_uint_16(entrybuf + 8, ep[i].frequency);
1273 }
1274
1275 png_write_chunk_data(png_ptr, entrybuf, entry_size);
1276 }
1277 #endif
1278
1279 png_write_chunk_end(png_ptr);
1280 }
1281 #endif
1282
1283 #ifdef PNG_WRITE_sBIT_SUPPORTED
1284 /* Write the sBIT chunk */
1285 void /* PRIVATE */
1286 png_write_sBIT(png_structrp png_ptr, png_const_color_8p sbit, int color_type)
1287 {
1288 png_byte buf[4];
1289 png_size_t size;
1290
1291 png_debug(1, "in png_write_sBIT");
1292
1293 /* Make sure we don't depend upon the order of PNG_COLOR_8 */
1294 if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
1295 {
1296 png_byte maxbits;
1297
1298 maxbits = (png_byte)(color_type==PNG_COLOR_TYPE_PALETTE ? 8 :
1299 png_ptr->usr_bit_depth);
1300
1301 if (sbit->red == 0 || sbit->red > maxbits ||
1302 sbit->green == 0 || sbit->green > maxbits ||
1303 sbit->blue == 0 || sbit->blue > maxbits)
1304 {
1305 png_warning(png_ptr, "Invalid sBIT depth specified");
1306 return;
1307 }
1308
1309 buf[0] = sbit->red;
1310 buf[1] = sbit->green;
1311 buf[2] = sbit->blue;
1312 size = 3;
1313 }
1314
1315 else
1316 {
1317 if (sbit->gray == 0 || sbit->gray > png_ptr->usr_bit_depth)
1318 {
1319 png_warning(png_ptr, "Invalid sBIT depth specified");
1320 return;
1321 }
1322
1323 buf[0] = sbit->gray;
1324 size = 1;
1325 }
1326
1327 if ((color_type & PNG_COLOR_MASK_ALPHA) != 0)
1328 {
1329 if (sbit->alpha == 0 || sbit->alpha > png_ptr->usr_bit_depth)
1330 {
1331 png_warning(png_ptr, "Invalid sBIT depth specified");
1332 return;
1333 }
1334
1335 buf[size++] = sbit->alpha;
1336 }
1337
1338 png_write_complete_chunk(png_ptr, png_sBIT, buf, size);
1339 }
1340 #endif
1341
1342 #ifdef PNG_WRITE_cHRM_SUPPORTED
1343 /* Write the cHRM chunk */
1344 void /* PRIVATE */
1345 png_write_cHRM_fixed(png_structrp png_ptr, const png_xy *xy)
1346 {
1347 png_byte buf[32];
1348
1349 png_debug(1, "in png_write_cHRM");
1350
1351 /* Each value is saved in 1/100,000ths */
1352 png_save_int_32(buf, xy->whitex);
1353 png_save_int_32(buf + 4, xy->whitey);
1354
1355 png_save_int_32(buf + 8, xy->redx);
1356 png_save_int_32(buf + 12, xy->redy);
1357
1358 png_save_int_32(buf + 16, xy->greenx);
1359 png_save_int_32(buf + 20, xy->greeny);
1360
1361 png_save_int_32(buf + 24, xy->bluex);
1362 png_save_int_32(buf + 28, xy->bluey);
1363
1364 png_write_complete_chunk(png_ptr, png_cHRM, buf, 32);
1365 }
1366 #endif
1367
1368 #ifdef PNG_WRITE_tRNS_SUPPORTED
1369 /* Write the tRNS chunk */
1370 void /* PRIVATE */
1371 png_write_tRNS(png_structrp png_ptr, png_const_bytep trans_alpha,
1372 png_const_color_16p tran, int num_trans, int color_type)
1373 {
1374 png_byte buf[6];
1375
1376 png_debug(1, "in png_write_tRNS");
1377
1378 if (color_type == PNG_COLOR_TYPE_PALETTE)
1379 {
1380 if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette)
1381 {
1382 png_app_warning(png_ptr,
1383 "Invalid number of transparent colors specified");
1384 return;
1385 }
1386
1387 /* Write the chunk out as it is */
1388 png_write_complete_chunk(png_ptr, png_tRNS, trans_alpha,
1389 (png_size_t)num_trans);
1390 }
1391
1392 else if (color_type == PNG_COLOR_TYPE_GRAY)
1393 {
1394 /* One 16-bit value */
1395 if (tran->gray >= (1 << png_ptr->bit_depth))
1396 {
1397 png_app_warning(png_ptr,
1398 "Ignoring attempt to write tRNS chunk out-of-range for bit_depth");
1399
1400 return;
1401 }
1402
1403 png_save_uint_16(buf, tran->gray);
1404 png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)2);
1405 }
1406
1407 else if (color_type == PNG_COLOR_TYPE_RGB)
1408 {
1409 /* Three 16-bit values */
1410 png_save_uint_16(buf, tran->red);
1411 png_save_uint_16(buf + 2, tran->green);
1412 png_save_uint_16(buf + 4, tran->blue);
1413 #ifdef PNG_WRITE_16BIT_SUPPORTED
1414 if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]) != 0)
1415 #else
1416 if ((buf[0] | buf[2] | buf[4]) != 0)
1417 #endif
1418 {
1419 png_app_warning(png_ptr,
1420 "Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8");
1421 return;
1422 }
1423
1424 png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)6);
1425 }
1426
1427 else
1428 {
1429 png_app_warning(png_ptr, "Can't write tRNS with an alpha channel");
1430 }
1431 }
1432 #endif
1433
1434 #ifdef PNG_WRITE_bKGD_SUPPORTED
1435 /* Write the background chunk */
1436 void /* PRIVATE */
1437 png_write_bKGD(png_structrp png_ptr, png_const_color_16p back, int color_type)
1438 {
1439 png_byte buf[6];
1440
1441 png_debug(1, "in png_write_bKGD");
1442
1443 if (color_type == PNG_COLOR_TYPE_PALETTE)
1444 {
1445 if (
1446 #ifdef PNG_MNG_FEATURES_SUPPORTED
1447 (png_ptr->num_palette != 0 ||
1448 (png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0) &&
1449 #endif
1450 back->index >= png_ptr->num_palette)
1451 {
1452 png_warning(png_ptr, "Invalid background palette index");
1453 return;
1454 }
1455
1456 buf[0] = back->index;
1457 png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)1);
1458 }
1459
1460 else if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
1461 {
1462 png_save_uint_16(buf, back->red);
1463 png_save_uint_16(buf + 2, back->green);
1464 png_save_uint_16(buf + 4, back->blue);
1465 #ifdef PNG_WRITE_16BIT_SUPPORTED
1466 if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]) != 0)
1467 #else
1468 if ((buf[0] | buf[2] | buf[4]) != 0)
1469 #endif
1470 {
1471 png_warning(png_ptr,
1472 "Ignoring attempt to write 16-bit bKGD chunk when bit_depth is 8");
1473
1474 return;
1475 }
1476
1477 png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)6);
1478 }
1479
1480 else
1481 {
1482 if (back->gray >= (1 << png_ptr->bit_depth))
1483 {
1484 png_warning(png_ptr,
1485 "Ignoring attempt to write bKGD chunk out-of-range for bit_depth");
1486
1487 return;
1488 }
1489
1490 png_save_uint_16(buf, back->gray);
1491 png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)2);
1492 }
1493 }
1494 #endif
1495
1496 #ifdef PNG_WRITE_hIST_SUPPORTED
1497 /* Write the histogram */
1498 void /* PRIVATE */
1499 png_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, (png_size_t)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 */
1529 void /* PRIVATE */
1530 png_write_tEXt(png_structrp png_ptr, png_const_charp key, png_const_charp text,
1531 png_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 */
1572 void /* PRIVATE */
1573 png_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 */
1623 void /* PRIVATE */
1624 png_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 png_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 */
1723 void /* PRIVATE */
1724 png_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, (png_size_t)9);
1739 }
1740 #endif
1741 #ifdef PNG_WRITE_pCAL_SUPPORTED
1742 /* Write the pCAL chunk (described in the PNG extensions document) */
1743 void /* PRIVATE */
1744 png_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 png_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)(nparams * (sizeof (png_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, (png_size_t)10);
1794 png_write_chunk_data(png_ptr, (png_const_bytep)units, (png_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 */
1808 void /* PRIVATE */
1809 png_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 png_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 */
1838 void /* PRIVATE */
1839 png_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, (png_size_t)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 */
1862 void /* PRIVATE */
1863 png_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, (png_size_t)7);
1885 }
1886 #endif
1887
1888 /* Initializes the row writing capability of libpng */
1889 void /* PRIVATE */
1890 png_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 PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
1897
1898 /* Offset to next interlace block */
1899 static PNG_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 PNG_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 PNG_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. */
2004 void /* PRIVATE */
2005 png_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 PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
2012
2013 /* Offset to next interlace block */
2014 static PNG_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 PNG_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 PNG_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_size_t)(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 */
2095 void /* PRIVATE */
2096 png_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 PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
2102
2103 /* Offset to next interlace block */
2104 static PNG_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 + (png_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 + (png_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 + (png_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 png_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 + (png_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 */
2273 static void /* PRIVATE */
2274 png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row,
2275 png_size_t row_bytes);
2276
2277 #ifdef PNG_WRITE_FILTER_SUPPORTED
2278 static png_size_t /* PRIVATE */
2279 png_setup_sub_row(png_structrp png_ptr, const png_uint_32 bpp,
2280 const png_size_t row_bytes, const png_size_t lmins)
2281 {
2282 png_bytep rp, dp, lp;
2283 png_size_t i;
2284 png_size_t sum = 0;
2285 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 sum += (v < 128) ? v : 256 - v;
2294 }
2295
2296 for (lp = png_ptr->row_buf + 1; i < row_bytes;
2297 i++, rp++, lp++, dp++)
2298 {
2299 v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
2300 sum += (v < 128) ? v : 256 - v;
2301
2302 if (sum > lmins) /* We are already worse, don't continue. */
2303 break;
2304 }
2305
2306 return (sum);
2307 }
2308
2309 static png_size_t /* PRIVATE */
2310 png_setup_up_row(png_structrp png_ptr, const png_size_t row_bytes,
2311 const png_size_t lmins)
2312 {
2313 png_bytep rp, dp, pp;
2314 png_size_t i;
2315 png_size_t sum = 0;
2316 int v;
2317
2318 png_ptr->try_row[0] = PNG_FILTER_VALUE_UP;
2319
2320 for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1,
2321 pp = png_ptr->prev_row + 1; i < row_bytes;
2322 i++, rp++, pp++, dp++)
2323 {
2324 v = *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
2325 sum += (v < 128) ? v : 256 - v;
2326
2327 if (sum > lmins) /* We are already worse, don't continue. */
2328 break;
2329 }
2330
2331 return (sum);
2332 }
2333
2334 static png_size_t /* PRIVATE */
2335 png_setup_avg_row(png_structrp png_ptr, const png_uint_32 bpp,
2336 const png_size_t row_bytes, const png_size_t lmins)
2337 {
2338 png_bytep rp, dp, pp, lp;
2339 png_uint_32 i;
2340 png_size_t sum = 0;
2341 int v;
2342
2343 png_ptr->try_row[0] = PNG_FILTER_VALUE_AVG;
2344
2345 for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1,
2346 pp = png_ptr->prev_row + 1; i < bpp; i++)
2347 {
2348 v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
2349
2350 sum += (v < 128) ? v : 256 - v;
2351 }
2352
2353 for (lp = png_ptr->row_buf + 1; i < row_bytes; i++)
2354 {
2355 v = *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
2356 & 0xff);
2357
2358 sum += (v < 128) ? v : 256 - v;
2359
2360 if (sum > lmins) /* We are already worse, don't continue. */
2361 break;
2362 }
2363
2364 return (sum);
2365 }
2366
2367 static png_size_t /* PRIVATE */
2368 png_setup_paeth_row(png_structrp png_ptr, const png_uint_32 bpp,
2369 const png_size_t row_bytes, const png_size_t lmins)
2370 {
2371 png_bytep rp, dp, pp, cp, lp;
2372 png_size_t i;
2373 png_size_t sum = 0;
2374 int v;
2375
2376 png_ptr->try_row[0] = PNG_FILTER_VALUE_PAETH;
2377
2378 for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1,
2379 pp = png_ptr->prev_row + 1; i < bpp; i++)
2380 {
2381 v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2382
2383 sum += (v < 128) ? v : 256 - v;
2384 }
2385
2386 for (lp = png_ptr->row_buf + 1, cp = png_ptr->prev_row + 1; i < row_bytes;
2387 i++)
2388 {
2389 int a, b, c, pa, pb, pc, p;
2390
2391 b = *pp++;
2392 c = *cp++;
2393 a = *lp++;
2394
2395 p = b - c;
2396 pc = a - c;
2397
2398 #ifdef PNG_USE_ABS
2399 pa = abs(p);
2400 pb = abs(pc);
2401 pc = abs(p + pc);
2402 #else
2403 pa = p < 0 ? -p : p;
2404 pb = pc < 0 ? -pc : pc;
2405 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
2406 #endif
2407
2408 p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
2409
2410 v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
2411
2412 sum += (v < 128) ? v : 256 - v;
2413
2414 if (sum > lmins) /* We are already worse, don't continue. */
2415 break;
2416 }
2417
2418 return (sum);
2419 }
2420 #endif /* WRITE_FILTER */
2421
2422 void /* PRIVATE */
2423 png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
2424 {
2425 #ifndef PNG_WRITE_FILTER_SUPPORTED
2426 png_write_filtered_row(png_ptr, png_ptr->row_buf, row_info->rowbytes+1);
2427 #else
2428 png_byte filter_to_do = png_ptr->do_filter;
2429 png_bytep row_buf;
2430 png_bytep best_row;
2431 png_uint_32 bpp;
2432 png_size_t mins;
2433 png_size_t row_bytes = row_info->rowbytes;
2434
2435 png_debug(1, "in png_write_find_filter");
2436
2437 /* Find out how many bytes offset each pixel is */
2438 bpp = (row_info->pixel_depth + 7) >> 3;
2439
2440 row_buf = png_ptr->row_buf;
2441 mins = PNG_SIZE_MAX - 256/* so we can detect potential overflow of the
2442 running sum */;
2443
2444 /* The prediction method we use is to find which method provides the
2445 * smallest value when summing the absolute values of the distances
2446 * from zero, using anything >= 128 as negative numbers. This is known
2447 * as the "minimum sum of absolute differences" heuristic. Other
2448 * heuristics are the "weighted minimum sum of absolute differences"
2449 * (experimental and can in theory improve compression), and the "zlib
2450 * predictive" method (not implemented yet), which does test compressions
2451 * of lines using different filter methods, and then chooses the
2452 * (series of) filter(s) that give minimum compressed data size (VERY
2453 * computationally expensive).
2454 *
2455 * GRR 980525: consider also
2456 *
2457 * (1) minimum sum of absolute differences from running average (i.e.,
2458 * keep running sum of non-absolute differences & count of bytes)
2459 * [track dispersion, too? restart average if dispersion too large?]
2460 *
2461 * (1b) minimum sum of absolute differences from sliding average, probably
2462 * with window size <= deflate window (usually 32K)
2463 *
2464 * (2) minimum sum of squared differences from zero or running average
2465 * (i.e., ~ root-mean-square approach)
2466 */
2467
2468
2469 /* We don't need to test the 'no filter' case if this is the only filter
2470 * that has been chosen, as it doesn't actually do anything to the data.
2471 */
2472 best_row = png_ptr->row_buf;
2473
2474
2475 if ((filter_to_do & PNG_FILTER_NONE) != 0 && filter_to_do != PNG_FILTER_NONE)
2476 {
2477 png_bytep rp;
2478 png_size_t sum = 0;
2479 png_size_t i;
2480 int v;
2481
2482 if (PNG_SIZE_MAX/128 <= row_bytes)
2483 {
2484 for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
2485 {
2486 /* Check for overflow */
2487 if (sum > PNG_SIZE_MAX/128 - 256)
2488 break;
2489
2490 v = *rp;
2491 sum += (v < 128) ? v : 256 - v;
2492 }
2493 }
2494 else /* Overflow is not possible */
2495 {
2496 for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
2497 {
2498 v = *rp;
2499 sum += (v < 128) ? v : 256 - v;
2500 }
2501 }
2502
2503 mins = sum;
2504 }
2505
2506 /* Sub filter */
2507 if (filter_to_do == PNG_FILTER_SUB)
2508 /* It's the only filter so no testing is needed */
2509 {
2510 (void) png_setup_sub_row(png_ptr, bpp, row_bytes, mins);
2511 best_row = png_ptr->try_row;
2512 }
2513
2514 else if ((filter_to_do & PNG_FILTER_SUB) != 0)
2515 {
2516 png_size_t sum;
2517 png_size_t lmins = mins;
2518
2519 sum = png_setup_sub_row(png_ptr, bpp, row_bytes, lmins);
2520
2521 if (sum < mins)
2522 {
2523 mins = sum;
2524 best_row = png_ptr->try_row;
2525 if (png_ptr->tst_row != NULL)
2526 {
2527 png_ptr->try_row = png_ptr->tst_row;
2528 png_ptr->tst_row = best_row;
2529 }
2530 }
2531 }
2532
2533 /* Up filter */
2534 if (filter_to_do == PNG_FILTER_UP)
2535 {
2536 (void) png_setup_up_row(png_ptr, row_bytes, mins);
2537 best_row = png_ptr->try_row;
2538 }
2539
2540 else if ((filter_to_do & PNG_FILTER_UP) != 0)
2541 {
2542 png_size_t sum;
2543 png_size_t lmins = mins;
2544
2545 sum = png_setup_up_row(png_ptr, row_bytes, lmins);
2546
2547 if (sum < mins)
2548 {
2549 mins = sum;
2550 best_row = png_ptr->try_row;
2551 if (png_ptr->tst_row != NULL)
2552 {
2553 png_ptr->try_row = png_ptr->tst_row;
2554 png_ptr->tst_row = best_row;
2555 }
2556 }
2557 }
2558
2559 /* Avg filter */
2560 if (filter_to_do == PNG_FILTER_AVG)
2561 {
2562 (void) png_setup_avg_row(png_ptr, bpp, row_bytes, mins);
2563 best_row = png_ptr->try_row;
2564 }
2565
2566 else if ((filter_to_do & PNG_FILTER_AVG) != 0)
2567 {
2568 png_size_t sum;
2569 png_size_t lmins = mins;
2570
2571 sum= png_setup_avg_row(png_ptr, bpp, row_bytes, lmins);
2572
2573 if (sum < mins)
2574 {
2575 mins = sum;
2576 best_row = png_ptr->try_row;
2577 if (png_ptr->tst_row != NULL)
2578 {
2579 png_ptr->try_row = png_ptr->tst_row;
2580 png_ptr->tst_row = best_row;
2581 }
2582 }
2583 }
2584
2585 /* Paeth filter */
2586 if ((filter_to_do == PNG_FILTER_PAETH) != 0)
2587 {
2588 (void) png_setup_paeth_row(png_ptr, bpp, row_bytes, mins);
2589 best_row = png_ptr->try_row;
2590 }
2591
2592 else if ((filter_to_do & PNG_FILTER_PAETH) != 0)
2593 {
2594 png_size_t sum;
2595 png_size_t lmins = mins;
2596
2597 sum = png_setup_paeth_row(png_ptr, bpp, row_bytes, lmins);
2598
2599 if (sum < mins)
2600 {
2601 best_row = png_ptr->try_row;
2602 if (png_ptr->tst_row != NULL)
2603 {
2604 png_ptr->try_row = png_ptr->tst_row;
2605 png_ptr->tst_row = best_row;
2606 }
2607 }
2608 }
2609
2610 /* Do the actual writing of the filtered row data from the chosen filter. */
2611 png_write_filtered_row(png_ptr, best_row, row_info->rowbytes+1);
2612
2613 #endif /* WRITE_FILTER */
2614 }
2615
2616
2617 /* Do the actual writing of a previously filtered row. */
2618 static void
2619 png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row,
2620 png_size_t full_row_length/*includes filter byte*/)
2621 {
2622 png_debug(1, "in png_write_filtered_row");
2623
2624 png_debug1(2, "filter = %d", filtered_row[0]);
2625
2626 png_compress_IDAT(png_ptr, filtered_row, full_row_length, Z_NO_FLUSH);
2627
2628 #ifdef PNG_WRITE_FILTER_SUPPORTED
2629 /* Swap the current and previous rows */
2630 if (png_ptr->prev_row != NULL)
2631 {
2632 png_bytep tptr;
2633
2634 tptr = png_ptr->prev_row;
2635 png_ptr->prev_row = png_ptr->row_buf;
2636 png_ptr->row_buf = tptr;
2637 }
2638 #endif /* WRITE_FILTER */
2639
2640 /* Finish row - updates counters and flushes zlib if last row */
2641 png_write_finish_row(png_ptr);
2642
2643 #ifdef PNG_WRITE_FLUSH_SUPPORTED
2644 png_ptr->flush_rows++;
2645
2646 if (png_ptr->flush_dist > 0 &&
2647 png_ptr->flush_rows >= png_ptr->flush_dist)
2648 {
2649 png_write_flush(png_ptr);
2650 }
2651 #endif /* WRITE_FLUSH */
2652 }
2653 #endif /* WRITE */