adc4729c24168bfe95730c604d1dd5e5c61b6846
[reactos.git] / reactos / dll / 3rdparty / libpng / pngwutil.c
1
2 /* pngwutil.c - utilities to write a PNG file
3 *
4 * Last changed in libpng 1.6.19 [November 12, 2015]
5 * Copyright (c) 1998-2015 Glenn Randers-Pehrson
6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
8 *
9 * This code is released under the libpng license.
10 * For conditions of distribution and use, see the disclaimer
11 * and license in png.h
12 */
13
14 #include "pngpriv.h"
15
16 #ifdef PNG_WRITE_SUPPORTED
17
18 #ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
19 /* Place a 32-bit number into a buffer in PNG byte order. We work
20 * with unsigned numbers for convenience, although one supported
21 * ancillary chunk uses signed (two's complement) numbers.
22 */
23 void PNGAPI
24 png_save_uint_32(png_bytep buf, png_uint_32 i)
25 {
26 buf[0] = (png_byte)(i >> 24);
27 buf[1] = (png_byte)(i >> 16);
28 buf[2] = (png_byte)(i >> 8);
29 buf[3] = (png_byte)(i );
30 }
31
32 /* Place a 16-bit number into a buffer in PNG byte order.
33 * The parameter is declared unsigned int, not png_uint_16,
34 * just to avoid potential problems on pre-ANSI C compilers.
35 */
36 void PNGAPI
37 png_save_uint_16(png_bytep buf, unsigned int i)
38 {
39 buf[0] = (png_byte)(i >> 8);
40 buf[1] = (png_byte)(i );
41 }
42 #endif
43
44 /* Simple function to write the signature. If we have already written
45 * the magic bytes of the signature, or more likely, the PNG stream is
46 * being embedded into another stream and doesn't need its own signature,
47 * we should call png_set_sig_bytes() to tell libpng how many of the
48 * bytes have already been written.
49 */
50 void PNGAPI
51 png_write_sig(png_structrp png_ptr)
52 {
53 png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
54
55 #ifdef PNG_IO_STATE_SUPPORTED
56 /* Inform the I/O callback that the signature is being written */
57 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_SIGNATURE;
58 #endif
59
60 /* Write the rest of the 8 byte signature */
61 png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes],
62 (png_size_t)(8 - png_ptr->sig_bytes));
63
64 if (png_ptr->sig_bytes < 3)
65 png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
66 }
67
68 /* Write the start of a PNG chunk. The type is the chunk type.
69 * The total_length is the sum of the lengths of all the data you will be
70 * passing in png_write_chunk_data().
71 */
72 static void
73 png_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
114 void PNGAPI
115 png_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 */
126 void PNGAPI
127 png_write_chunk_data(png_structrp png_ptr, png_const_bytep data,
128 png_size_t length)
129 {
130 /* Write the data, and run the CRC over it */
131 if (png_ptr == NULL)
132 return;
133
134 if (data != NULL && length > 0)
135 {
136 png_write_data(png_ptr, data, length);
137
138 /* Update the CRC after writing the data,
139 * in case the user I/O routine alters it.
140 */
141 png_calculate_crc(png_ptr, data, length);
142 }
143 }
144
145 /* Finish a chunk started with png_write_chunk_header(). */
146 void PNGAPI
147 png_write_chunk_end(png_structrp png_ptr)
148 {
149 png_byte buf[4];
150
151 if (png_ptr == NULL) return;
152
153 #ifdef PNG_IO_STATE_SUPPORTED
154 /* Inform the I/O callback that the chunk CRC is being written.
155 * PNG_IO_CHUNK_CRC requires a single I/O function call.
156 */
157 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_CRC;
158 #endif
159
160 /* Write the crc in a single operation */
161 png_save_uint_32(buf, png_ptr->crc);
162
163 png_write_data(png_ptr, buf, (png_size_t)4);
164 }
165
166 /* Write a PNG chunk all at once. The type is an array of ASCII characters
167 * representing the chunk name. The array must be at least 4 bytes in
168 * length, and does not need to be null terminated. To be safe, pass the
169 * pre-defined chunk names here, and if you need a new one, define it
170 * where the others are defined. The length is the length of the data.
171 * All the data must be present. If that is not possible, use the
172 * png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end()
173 * functions instead.
174 */
175 static void
176 png_write_complete_chunk(png_structrp png_ptr, png_uint_32 chunk_name,
177 png_const_bytep data, png_size_t length)
178 {
179 if (png_ptr == NULL)
180 return;
181
182 /* On 64-bit architectures 'length' may not fit in a png_uint_32. */
183 if (length > PNG_UINT_31_MAX)
184 png_error(png_ptr, "length exceeds PNG maximum");
185
186 png_write_chunk_header(png_ptr, chunk_name, (png_uint_32)length);
187 png_write_chunk_data(png_ptr, data, length);
188 png_write_chunk_end(png_ptr);
189 }
190
191 /* This is the API that calls the internal function above. */
192 void PNGAPI
193 png_write_chunk(png_structrp png_ptr, png_const_bytep chunk_string,
194 png_const_bytep data, png_size_t length)
195 {
196 png_write_complete_chunk(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), data,
197 length);
198 }
199
200 /* This is used below to find the size of an image to pass to png_deflate_claim,
201 * so it only needs to be accurate if the size is less than 16384 bytes (the
202 * point at which a lower LZ window size can be used.)
203 */
204 static png_alloc_size_t
205 png_image_size(png_structrp png_ptr)
206 {
207 /* Only return sizes up to the maximum of a png_uint_32; do this by limiting
208 * the width and height used to 15 bits.
209 */
210 png_uint_32 h = png_ptr->height;
211
212 if (png_ptr->rowbytes < 32768 && h < 32768)
213 {
214 if (png_ptr->interlaced != 0)
215 {
216 /* Interlacing makes the image larger because of the replication of
217 * both the filter byte and the padding to a byte boundary.
218 */
219 png_uint_32 w = png_ptr->width;
220 unsigned int pd = png_ptr->pixel_depth;
221 png_alloc_size_t cb_base;
222 int pass;
223
224 for (cb_base=0, pass=0; pass<=6; ++pass)
225 {
226 png_uint_32 pw = PNG_PASS_COLS(w, pass);
227
228 if (pw > 0)
229 cb_base += (PNG_ROWBYTES(pd, pw)+1) * PNG_PASS_ROWS(h, pass);
230 }
231
232 return cb_base;
233 }
234
235 else
236 return (png_ptr->rowbytes+1) * h;
237 }
238
239 else
240 return 0xffffffffU;
241 }
242
243 #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
244 /* This is the code to hack the first two bytes of the deflate stream (the
245 * deflate header) to correct the windowBits value to match the actual data
246 * size. Note that the second argument is the *uncompressed* size but the
247 * first argument is the *compressed* data (and it must be deflate
248 * compressed.)
249 */
250 static void
251 optimize_cmf(png_bytep data, png_alloc_size_t data_size)
252 {
253 /* Optimize the CMF field in the zlib stream. The resultant zlib stream is
254 * still compliant to the stream specification.
255 */
256 if (data_size <= 16384) /* else windowBits must be 15 */
257 {
258 unsigned int z_cmf = data[0]; /* zlib compression method and flags */
259
260 if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
261 {
262 unsigned int z_cinfo;
263 unsigned int half_z_window_size;
264
265 z_cinfo = z_cmf >> 4;
266 half_z_window_size = 1U << (z_cinfo + 7);
267
268 if (data_size <= half_z_window_size) /* else no change */
269 {
270 unsigned int tmp;
271
272 do
273 {
274 half_z_window_size >>= 1;
275 --z_cinfo;
276 }
277 while (z_cinfo > 0 && data_size <= half_z_window_size);
278
279 z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
280
281 data[0] = (png_byte)z_cmf;
282 tmp = data[1] & 0xe0;
283 tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
284 data[1] = (png_byte)tmp;
285 }
286 }
287 }
288 }
289 #endif /* WRITE_OPTIMIZE_CMF */
290
291 /* Initialize the compressor for the appropriate type of compression. */
292 static int
293 png_deflate_claim(png_structrp png_ptr, png_uint_32 owner,
294 png_alloc_size_t data_size)
295 {
296 if (png_ptr->zowner != 0)
297 {
298 #if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_ERROR_TEXT_SUPPORTED)
299 char msg[64];
300
301 PNG_STRING_FROM_CHUNK(msg, owner);
302 msg[4] = ':';
303 msg[5] = ' ';
304 PNG_STRING_FROM_CHUNK(msg+6, png_ptr->zowner);
305 /* So the message that results is "<chunk> using zstream"; this is an
306 * internal error, but is very useful for debugging. i18n requirements
307 * are minimal.
308 */
309 (void)png_safecat(msg, (sizeof msg), 10, " using zstream");
310 #endif
311 #if PNG_RELEASE_BUILD
312 png_warning(png_ptr, msg);
313
314 /* Attempt sane error recovery */
315 if (png_ptr->zowner == png_IDAT) /* don't steal from IDAT */
316 {
317 png_ptr->zstream.msg = PNGZ_MSG_CAST("in use by IDAT");
318 return Z_STREAM_ERROR;
319 }
320
321 png_ptr->zowner = 0;
322 #else
323 png_error(png_ptr, msg);
324 #endif
325 }
326
327 {
328 int level = png_ptr->zlib_level;
329 int method = png_ptr->zlib_method;
330 int windowBits = png_ptr->zlib_window_bits;
331 int memLevel = png_ptr->zlib_mem_level;
332 int strategy; /* set below */
333 int ret; /* zlib return code */
334
335 if (owner == png_IDAT)
336 {
337 if ((png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY) != 0)
338 strategy = png_ptr->zlib_strategy;
339
340 else if (png_ptr->do_filter != PNG_FILTER_NONE)
341 strategy = PNG_Z_DEFAULT_STRATEGY;
342
343 else
344 strategy = PNG_Z_DEFAULT_NOFILTER_STRATEGY;
345 }
346
347 else
348 {
349 #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
350 level = png_ptr->zlib_text_level;
351 method = png_ptr->zlib_text_method;
352 windowBits = png_ptr->zlib_text_window_bits;
353 memLevel = png_ptr->zlib_text_mem_level;
354 strategy = png_ptr->zlib_text_strategy;
355 #else
356 /* If customization is not supported the values all come from the
357 * IDAT values except for the strategy, which is fixed to the
358 * default. (This is the pre-1.6.0 behavior too, although it was
359 * implemented in a very different way.)
360 */
361 strategy = Z_DEFAULT_STRATEGY;
362 #endif
363 }
364
365 /* Adjust 'windowBits' down if larger than 'data_size'; to stop this
366 * happening just pass 32768 as the data_size parameter. Notice that zlib
367 * requires an extra 262 bytes in the window in addition to the data to be
368 * able to see the whole of the data, so if data_size+262 takes us to the
369 * next windowBits size we need to fix up the value later. (Because even
370 * though deflate needs the extra window, inflate does not!)
371 */
372 if (data_size <= 16384)
373 {
374 /* IMPLEMENTATION NOTE: this 'half_window_size' stuff is only here to
375 * work round a Microsoft Visual C misbehavior which, contrary to C-90,
376 * widens the result of the following shift to 64-bits if (and,
377 * apparently, only if) it is used in a test.
378 */
379 unsigned int half_window_size = 1U << (windowBits-1);
380
381 while (data_size + 262 <= half_window_size)
382 {
383 half_window_size >>= 1;
384 --windowBits;
385 }
386 }
387
388 /* Check against the previous initialized values, if any. */
389 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0 &&
390 (png_ptr->zlib_set_level != level ||
391 png_ptr->zlib_set_method != method ||
392 png_ptr->zlib_set_window_bits != windowBits ||
393 png_ptr->zlib_set_mem_level != memLevel ||
394 png_ptr->zlib_set_strategy != strategy))
395 {
396 if (deflateEnd(&png_ptr->zstream) != Z_OK)
397 png_warning(png_ptr, "deflateEnd failed (ignored)");
398
399 png_ptr->flags &= ~PNG_FLAG_ZSTREAM_INITIALIZED;
400 }
401
402 /* For safety clear out the input and output pointers (currently zlib
403 * doesn't use them on Init, but it might in the future).
404 */
405 png_ptr->zstream.next_in = NULL;
406 png_ptr->zstream.avail_in = 0;
407 png_ptr->zstream.next_out = NULL;
408 png_ptr->zstream.avail_out = 0;
409
410 /* Now initialize if required, setting the new parameters, otherwise just
411 * to a simple reset to the previous parameters.
412 */
413 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
414 ret = deflateReset(&png_ptr->zstream);
415
416 else
417 {
418 ret = deflateInit2(&png_ptr->zstream, level, method, windowBits,
419 memLevel, strategy);
420
421 if (ret == Z_OK)
422 png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
423 }
424
425 /* The return code is from either deflateReset or deflateInit2; they have
426 * pretty much the same set of error codes.
427 */
428 if (ret == Z_OK)
429 png_ptr->zowner = owner;
430
431 else
432 png_zstream_error(png_ptr, ret);
433
434 return ret;
435 }
436 }
437
438 /* Clean up (or trim) a linked list of compression buffers. */
439 void /* PRIVATE */
440 png_free_buffer_list(png_structrp png_ptr, png_compression_bufferp *listp)
441 {
442 png_compression_bufferp list = *listp;
443
444 if (list != NULL)
445 {
446 *listp = NULL;
447
448 do
449 {
450 png_compression_bufferp next = list->next;
451
452 png_free(png_ptr, list);
453 list = next;
454 }
455 while (list != NULL);
456 }
457 }
458
459 #ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
460 /* This pair of functions encapsulates the operation of (a) compressing a
461 * text string, and (b) issuing it later as a series of chunk data writes.
462 * The compression_state structure is shared context for these functions
463 * set up by the caller to allow access to the relevant local variables.
464 *
465 * compression_buffer (new in 1.6.0) is just a linked list of zbuffer_size
466 * temporary buffers. From 1.6.0 it is retained in png_struct so that it will
467 * be correctly freed in the event of a write error (previous implementations
468 * just leaked memory.)
469 */
470 typedef struct
471 {
472 png_const_bytep input; /* The uncompressed input data */
473 png_alloc_size_t input_len; /* Its length */
474 png_uint_32 output_len; /* Final compressed length */
475 png_byte output[1024]; /* First block of output */
476 } compression_state;
477
478 static void
479 png_text_compress_init(compression_state *comp, png_const_bytep input,
480 png_alloc_size_t input_len)
481 {
482 comp->input = input;
483 comp->input_len = input_len;
484 comp->output_len = 0;
485 }
486
487 /* Compress the data in the compression state input */
488 static int
489 png_text_compress(png_structrp png_ptr, png_uint_32 chunk_name,
490 compression_state *comp, png_uint_32 prefix_len)
491 {
492 int ret;
493
494 /* To find the length of the output it is necessary to first compress the
495 * input. The result is buffered rather than using the two-pass algorithm
496 * that is used on the inflate side; deflate is assumed to be slower and a
497 * PNG writer is assumed to have more memory available than a PNG reader.
498 *
499 * IMPLEMENTATION NOTE: the zlib API deflateBound() can be used to find an
500 * upper limit on the output size, but it is always bigger than the input
501 * size so it is likely to be more efficient to use this linked-list
502 * approach.
503 */
504 ret = png_deflate_claim(png_ptr, chunk_name, comp->input_len);
505
506 if (ret != Z_OK)
507 return ret;
508
509 /* Set up the compression buffers, we need a loop here to avoid overflowing a
510 * uInt. Use ZLIB_IO_MAX to limit the input. The output is always limited
511 * by the output buffer size, so there is no need to check that. Since this
512 * is ANSI-C we know that an 'int', hence a uInt, is always at least 16 bits
513 * in size.
514 */
515 {
516 png_compression_bufferp *end = &png_ptr->zbuffer_list;
517 png_alloc_size_t input_len = comp->input_len; /* may be zero! */
518 png_uint_32 output_len;
519
520 /* zlib updates these for us: */
521 png_ptr->zstream.next_in = PNGZ_INPUT_CAST(comp->input);
522 png_ptr->zstream.avail_in = 0; /* Set below */
523 png_ptr->zstream.next_out = comp->output;
524 png_ptr->zstream.avail_out = (sizeof comp->output);
525
526 output_len = png_ptr->zstream.avail_out;
527
528 do
529 {
530 uInt avail_in = ZLIB_IO_MAX;
531
532 if (avail_in > input_len)
533 avail_in = (uInt)input_len;
534
535 input_len -= avail_in;
536
537 png_ptr->zstream.avail_in = avail_in;
538
539 if (png_ptr->zstream.avail_out == 0)
540 {
541 png_compression_buffer *next;
542
543 /* Chunk data is limited to 2^31 bytes in length, so the prefix
544 * length must be counted here.
545 */
546 if (output_len + prefix_len > PNG_UINT_31_MAX)
547 {
548 ret = Z_MEM_ERROR;
549 break;
550 }
551
552 /* Need a new (malloc'ed) buffer, but there may be one present
553 * already.
554 */
555 next = *end;
556 if (next == NULL)
557 {
558 next = png_voidcast(png_compression_bufferp, png_malloc_base
559 (png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr)));
560
561 if (next == NULL)
562 {
563 ret = Z_MEM_ERROR;
564 break;
565 }
566
567 /* Link in this buffer (so that it will be freed later) */
568 next->next = NULL;
569 *end = next;
570 }
571
572 png_ptr->zstream.next_out = next->output;
573 png_ptr->zstream.avail_out = png_ptr->zbuffer_size;
574 output_len += png_ptr->zstream.avail_out;
575
576 /* Move 'end' to the next buffer pointer. */
577 end = &next->next;
578 }
579
580 /* Compress the data */
581 ret = deflate(&png_ptr->zstream,
582 input_len > 0 ? Z_NO_FLUSH : Z_FINISH);
583
584 /* Claw back input data that was not consumed (because avail_in is
585 * reset above every time round the loop).
586 */
587 input_len += png_ptr->zstream.avail_in;
588 png_ptr->zstream.avail_in = 0; /* safety */
589 }
590 while (ret == Z_OK);
591
592 /* There may be some space left in the last output buffer. This needs to
593 * be subtracted from output_len.
594 */
595 output_len -= png_ptr->zstream.avail_out;
596 png_ptr->zstream.avail_out = 0; /* safety */
597 comp->output_len = output_len;
598
599 /* Now double check the output length, put in a custom message if it is
600 * too long. Otherwise ensure the z_stream::msg pointer is set to
601 * something.
602 */
603 if (output_len + prefix_len >= PNG_UINT_31_MAX)
604 {
605 png_ptr->zstream.msg = PNGZ_MSG_CAST("compressed data too long");
606 ret = Z_MEM_ERROR;
607 }
608
609 else
610 png_zstream_error(png_ptr, ret);
611
612 /* Reset zlib for another zTXt/iTXt or image data */
613 png_ptr->zowner = 0;
614
615 /* The only success case is Z_STREAM_END, input_len must be 0; if not this
616 * is an internal error.
617 */
618 if (ret == Z_STREAM_END && input_len == 0)
619 {
620 #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
621 /* Fix up the deflate header, if required */
622 optimize_cmf(comp->output, comp->input_len);
623 #endif
624 /* But Z_OK is returned, not Z_STREAM_END; this allows the claim
625 * function above to return Z_STREAM_END on an error (though it never
626 * does in the current versions of zlib.)
627 */
628 return Z_OK;
629 }
630
631 else
632 return ret;
633 }
634 }
635
636 /* Ship the compressed text out via chunk writes */
637 static void
638 png_write_compressed_data_out(png_structrp png_ptr, compression_state *comp)
639 {
640 png_uint_32 output_len = comp->output_len;
641 png_const_bytep output = comp->output;
642 png_uint_32 avail = (sizeof comp->output);
643 png_compression_buffer *next = png_ptr->zbuffer_list;
644
645 for (;;)
646 {
647 if (avail > output_len)
648 avail = output_len;
649
650 png_write_chunk_data(png_ptr, output, avail);
651
652 output_len -= avail;
653
654 if (output_len == 0 || next == NULL)
655 break;
656
657 avail = png_ptr->zbuffer_size;
658 output = next->output;
659 next = next->next;
660 }
661
662 /* This is an internal error; 'next' must have been NULL! */
663 if (output_len > 0)
664 png_error(png_ptr, "error writing ancillary chunked compressed data");
665 }
666 #endif /* WRITE_COMPRESSED_TEXT */
667
668 #if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \
669 defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
670 /* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification,
671 * and if invalid, correct the keyword rather than discarding the entire
672 * chunk. The PNG 1.0 specification requires keywords 1-79 characters in
673 * length, forbids leading or trailing whitespace, multiple internal spaces,
674 * and the non-break space (0x80) from ISO 8859-1. Returns keyword length.
675 *
676 * The 'new_key' buffer must be 80 characters in size (for the keyword plus a
677 * trailing '\0'). If this routine returns 0 then there was no keyword, or a
678 * valid one could not be generated, and the caller must png_error.
679 */
680 static png_uint_32
681 png_check_keyword(png_structrp png_ptr, png_const_charp key, png_bytep new_key)
682 {
683 png_const_charp orig_key = key;
684 png_uint_32 key_len = 0;
685 int bad_character = 0;
686 int space = 1;
687
688 png_debug(1, "in png_check_keyword");
689
690 if (key == NULL)
691 {
692 *new_key = 0;
693 return 0;
694 }
695
696 while (*key && key_len < 79)
697 {
698 png_byte ch = (png_byte)*key++;
699
700 if ((ch > 32 && ch <= 126) || (ch >= 161 /*&& ch <= 255*/))
701 *new_key++ = ch, ++key_len, space = 0;
702
703 else if (space == 0)
704 {
705 /* A space or an invalid character when one wasn't seen immediately
706 * before; output just a space.
707 */
708 *new_key++ = 32, ++key_len, space = 1;
709
710 /* If the character was not a space then it is invalid. */
711 if (ch != 32)
712 bad_character = ch;
713 }
714
715 else if (bad_character == 0)
716 bad_character = ch; /* just skip it, record the first error */
717 }
718
719 if (key_len > 0 && space != 0) /* trailing space */
720 {
721 --key_len, --new_key;
722 if (bad_character == 0)
723 bad_character = 32;
724 }
725
726 /* Terminate the keyword */
727 *new_key = 0;
728
729 if (key_len == 0)
730 return 0;
731
732 #ifdef PNG_WARNINGS_SUPPORTED
733 /* Try to only output one warning per keyword: */
734 if (*key != 0) /* keyword too long */
735 png_warning(png_ptr, "keyword truncated");
736
737 else if (bad_character != 0)
738 {
739 PNG_WARNING_PARAMETERS(p)
740
741 png_warning_parameter(p, 1, orig_key);
742 png_warning_parameter_signed(p, 2, PNG_NUMBER_FORMAT_02x, bad_character);
743
744 png_formatted_warning(png_ptr, p, "keyword \"@1\": bad character '0x@2'");
745 }
746 #endif /* WARNINGS */
747
748 return key_len;
749 }
750 #endif /* WRITE_TEXT || WRITE_pCAL || WRITE_iCCP || WRITE_sPLT */
751
752 /* Write the IHDR chunk, and update the png_struct with the necessary
753 * information. Note that the rest of this code depends upon this
754 * information being correct.
755 */
756 void /* PRIVATE */
757 png_write_IHDR(png_structrp png_ptr, png_uint_32 width, png_uint_32 height,
758 int bit_depth, int color_type, int compression_type, int filter_type,
759 int interlace_type)
760 {
761 png_byte buf[13]; /* Buffer to store the IHDR info */
762
763 png_debug(1, "in png_write_IHDR");
764
765 /* Check that we have valid input data from the application info */
766 switch (color_type)
767 {
768 case PNG_COLOR_TYPE_GRAY:
769 switch (bit_depth)
770 {
771 case 1:
772 case 2:
773 case 4:
774 case 8:
775 #ifdef PNG_WRITE_16BIT_SUPPORTED
776 case 16:
777 #endif
778 png_ptr->channels = 1; break;
779
780 default:
781 png_error(png_ptr,
782 "Invalid bit depth for grayscale image");
783 }
784 break;
785
786 case PNG_COLOR_TYPE_RGB:
787 #ifdef PNG_WRITE_16BIT_SUPPORTED
788 if (bit_depth != 8 && bit_depth != 16)
789 #else
790 if (bit_depth != 8)
791 #endif
792 png_error(png_ptr, "Invalid bit depth for RGB image");
793
794 png_ptr->channels = 3;
795 break;
796
797 case PNG_COLOR_TYPE_PALETTE:
798 switch (bit_depth)
799 {
800 case 1:
801 case 2:
802 case 4:
803 case 8:
804 png_ptr->channels = 1;
805 break;
806
807 default:
808 png_error(png_ptr, "Invalid bit depth for paletted image");
809 }
810 break;
811
812 case PNG_COLOR_TYPE_GRAY_ALPHA:
813 if (bit_depth != 8 && bit_depth != 16)
814 png_error(png_ptr, "Invalid bit depth for grayscale+alpha image");
815
816 png_ptr->channels = 2;
817 break;
818
819 case PNG_COLOR_TYPE_RGB_ALPHA:
820 #ifdef PNG_WRITE_16BIT_SUPPORTED
821 if (bit_depth != 8 && bit_depth != 16)
822 #else
823 if (bit_depth != 8)
824 #endif
825 png_error(png_ptr, "Invalid bit depth for RGBA image");
826
827 png_ptr->channels = 4;
828 break;
829
830 default:
831 png_error(png_ptr, "Invalid image color type specified");
832 }
833
834 if (compression_type != PNG_COMPRESSION_TYPE_BASE)
835 {
836 png_warning(png_ptr, "Invalid compression type specified");
837 compression_type = PNG_COMPRESSION_TYPE_BASE;
838 }
839
840 /* Write filter_method 64 (intrapixel differencing) only if
841 * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
842 * 2. Libpng did not write a PNG signature (this filter_method is only
843 * used in PNG datastreams that are embedded in MNG datastreams) and
844 * 3. The application called png_permit_mng_features with a mask that
845 * included PNG_FLAG_MNG_FILTER_64 and
846 * 4. The filter_method is 64 and
847 * 5. The color_type is RGB or RGBA
848 */
849 if (
850 #ifdef PNG_MNG_FEATURES_SUPPORTED
851 !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
852 ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
853 (color_type == PNG_COLOR_TYPE_RGB ||
854 color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&
855 (filter_type == PNG_INTRAPIXEL_DIFFERENCING)) &&
856 #endif
857 filter_type != PNG_FILTER_TYPE_BASE)
858 {
859 png_warning(png_ptr, "Invalid filter type specified");
860 filter_type = PNG_FILTER_TYPE_BASE;
861 }
862
863 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
864 if (interlace_type != PNG_INTERLACE_NONE &&
865 interlace_type != PNG_INTERLACE_ADAM7)
866 {
867 png_warning(png_ptr, "Invalid interlace type specified");
868 interlace_type = PNG_INTERLACE_ADAM7;
869 }
870 #else
871 interlace_type=PNG_INTERLACE_NONE;
872 #endif
873
874 /* Save the relevant information */
875 png_ptr->bit_depth = (png_byte)bit_depth;
876 png_ptr->color_type = (png_byte)color_type;
877 png_ptr->interlaced = (png_byte)interlace_type;
878 #ifdef PNG_MNG_FEATURES_SUPPORTED
879 png_ptr->filter_type = (png_byte)filter_type;
880 #endif
881 png_ptr->compression_type = (png_byte)compression_type;
882 png_ptr->width = width;
883 png_ptr->height = height;
884
885 png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels);
886 png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width);
887 /* Set the usr info, so any transformations can modify it */
888 png_ptr->usr_width = png_ptr->width;
889 png_ptr->usr_bit_depth = png_ptr->bit_depth;
890 png_ptr->usr_channels = png_ptr->channels;
891
892 /* Pack the header information into the buffer */
893 png_save_uint_32(buf, width);
894 png_save_uint_32(buf + 4, height);
895 buf[8] = (png_byte)bit_depth;
896 buf[9] = (png_byte)color_type;
897 buf[10] = (png_byte)compression_type;
898 buf[11] = (png_byte)filter_type;
899 buf[12] = (png_byte)interlace_type;
900
901 /* Write the chunk */
902 png_write_complete_chunk(png_ptr, png_IHDR, buf, (png_size_t)13);
903
904 if ((png_ptr->do_filter) == PNG_NO_FILTERS)
905 {
906 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
907 png_ptr->bit_depth < 8)
908 png_ptr->do_filter = PNG_FILTER_NONE;
909
910 else
911 png_ptr->do_filter = PNG_ALL_FILTERS;
912 }
913
914 png_ptr->mode = PNG_HAVE_IHDR; /* not READY_FOR_ZTXT */
915 }
916
917 /* Write the palette. We are careful not to trust png_color to be in the
918 * correct order for PNG, so people can redefine it to any convenient
919 * structure.
920 */
921 void /* PRIVATE */
922 png_write_PLTE(png_structrp png_ptr, png_const_colorp palette,
923 png_uint_32 num_pal)
924 {
925 png_uint_32 max_palette_length, i;
926 png_const_colorp pal_ptr;
927 png_byte buf[3];
928
929 png_debug(1, "in png_write_PLTE");
930
931 max_palette_length = (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ?
932 (1 << png_ptr->bit_depth) : PNG_MAX_PALETTE_LENGTH;
933
934 if ((
935 #ifdef PNG_MNG_FEATURES_SUPPORTED
936 (png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0 &&
937 #endif
938 num_pal == 0) || num_pal > max_palette_length)
939 {
940 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
941 {
942 png_error(png_ptr, "Invalid number of colors in palette");
943 }
944
945 else
946 {
947 png_warning(png_ptr, "Invalid number of colors in palette");
948 return;
949 }
950 }
951
952 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
953 {
954 png_warning(png_ptr,
955 "Ignoring request to write a PLTE chunk in grayscale PNG");
956
957 return;
958 }
959
960 png_ptr->num_palette = (png_uint_16)num_pal;
961 png_debug1(3, "num_palette = %d", png_ptr->num_palette);
962
963 png_write_chunk_header(png_ptr, png_PLTE, (png_uint_32)(num_pal * 3));
964 #ifdef PNG_POINTER_INDEXING_SUPPORTED
965
966 for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++)
967 {
968 buf[0] = pal_ptr->red;
969 buf[1] = pal_ptr->green;
970 buf[2] = pal_ptr->blue;
971 png_write_chunk_data(png_ptr, buf, (png_size_t)3);
972 }
973
974 #else
975 /* This is a little slower but some buggy compilers need to do this
976 * instead
977 */
978 pal_ptr=palette;
979
980 for (i = 0; i < num_pal; i++)
981 {
982 buf[0] = pal_ptr[i].red;
983 buf[1] = pal_ptr[i].green;
984 buf[2] = pal_ptr[i].blue;
985 png_write_chunk_data(png_ptr, buf, (png_size_t)3);
986 }
987
988 #endif
989 png_write_chunk_end(png_ptr);
990 png_ptr->mode |= PNG_HAVE_PLTE;
991 }
992
993 /* This is similar to png_text_compress, above, except that it does not require
994 * all of the data at once and, instead of buffering the compressed result,
995 * writes it as IDAT chunks. Unlike png_text_compress it *can* png_error out
996 * because it calls the write interface. As a result it does its own error
997 * reporting and does not return an error code. In the event of error it will
998 * just call png_error. The input data length may exceed 32-bits. The 'flush'
999 * parameter is exactly the same as that to deflate, with the following
1000 * meanings:
1001 *
1002 * Z_NO_FLUSH: normal incremental output of compressed data
1003 * Z_SYNC_FLUSH: do a SYNC_FLUSH, used by png_write_flush
1004 * Z_FINISH: this is the end of the input, do a Z_FINISH and clean up
1005 *
1006 * The routine manages the acquire and release of the png_ptr->zstream by
1007 * checking and (at the end) clearing png_ptr->zowner; it does some sanity
1008 * checks on the 'mode' flags while doing this.
1009 */
1010 void /* PRIVATE */
1011 png_compress_IDAT(png_structrp png_ptr, png_const_bytep input,
1012 png_alloc_size_t input_len, int flush)
1013 {
1014 if (png_ptr->zowner != png_IDAT)
1015 {
1016 /* First time. Ensure we have a temporary buffer for compression and
1017 * trim the buffer list if it has more than one entry to free memory.
1018 * If 'WRITE_COMPRESSED_TEXT' is not set the list will never have been
1019 * created at this point, but the check here is quick and safe.
1020 */
1021 if (png_ptr->zbuffer_list == NULL)
1022 {
1023 png_ptr->zbuffer_list = png_voidcast(png_compression_bufferp,
1024 png_malloc(png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr)));
1025 png_ptr->zbuffer_list->next = NULL;
1026 }
1027
1028 else
1029 png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list->next);
1030
1031 /* It is a terminal error if we can't claim the zstream. */
1032 if (png_deflate_claim(png_ptr, png_IDAT, png_image_size(png_ptr)) != Z_OK)
1033 png_error(png_ptr, png_ptr->zstream.msg);
1034
1035 /* The output state is maintained in png_ptr->zstream, so it must be
1036 * initialized here after the claim.
1037 */
1038 png_ptr->zstream.next_out = png_ptr->zbuffer_list->output;
1039 png_ptr->zstream.avail_out = png_ptr->zbuffer_size;
1040 }
1041
1042 /* Now loop reading and writing until all the input is consumed or an error
1043 * terminates the operation. The _out values are maintained across calls to
1044 * this function, but the input must be reset each time.
1045 */
1046 png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
1047 png_ptr->zstream.avail_in = 0; /* set below */
1048 for (;;)
1049 {
1050 int ret;
1051
1052 /* INPUT: from the row data */
1053 uInt avail = ZLIB_IO_MAX;
1054
1055 if (avail > input_len)
1056 avail = (uInt)input_len; /* safe because of the check */
1057
1058 png_ptr->zstream.avail_in = avail;
1059 input_len -= avail;
1060
1061 ret = deflate(&png_ptr->zstream, input_len > 0 ? Z_NO_FLUSH : flush);
1062
1063 /* Include as-yet unconsumed input */
1064 input_len += png_ptr->zstream.avail_in;
1065 png_ptr->zstream.avail_in = 0;
1066
1067 /* OUTPUT: write complete IDAT chunks when avail_out drops to zero. Note
1068 * that these two zstream fields are preserved across the calls, therefore
1069 * there is no need to set these up on entry to the loop.
1070 */
1071 if (png_ptr->zstream.avail_out == 0)
1072 {
1073 png_bytep data = png_ptr->zbuffer_list->output;
1074 uInt size = png_ptr->zbuffer_size;
1075
1076 /* Write an IDAT containing the data then reset the buffer. The
1077 * first IDAT may need deflate header optimization.
1078 */
1079 #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
1080 if ((png_ptr->mode & PNG_HAVE_IDAT) == 0 &&
1081 png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
1082 optimize_cmf(data, png_image_size(png_ptr));
1083 #endif
1084
1085 png_write_complete_chunk(png_ptr, png_IDAT, data, size);
1086 png_ptr->mode |= PNG_HAVE_IDAT;
1087
1088 png_ptr->zstream.next_out = data;
1089 png_ptr->zstream.avail_out = size;
1090
1091 /* For SYNC_FLUSH or FINISH it is essential to keep calling zlib with
1092 * the same flush parameter until it has finished output, for NO_FLUSH
1093 * it doesn't matter.
1094 */
1095 if (ret == Z_OK && flush != Z_NO_FLUSH)
1096 continue;
1097 }
1098
1099 /* The order of these checks doesn't matter much; it just affects which
1100 * possible error might be detected if multiple things go wrong at once.
1101 */
1102 if (ret == Z_OK) /* most likely return code! */
1103 {
1104 /* If all the input has been consumed then just return. If Z_FINISH
1105 * was used as the flush parameter something has gone wrong if we get
1106 * here.
1107 */
1108 if (input_len == 0)
1109 {
1110 if (flush == Z_FINISH)
1111 png_error(png_ptr, "Z_OK on Z_FINISH with output space");
1112
1113 return;
1114 }
1115 }
1116
1117 else if (ret == Z_STREAM_END && flush == Z_FINISH)
1118 {
1119 /* This is the end of the IDAT data; any pending output must be
1120 * flushed. For small PNG files we may still be at the beginning.
1121 */
1122 png_bytep data = png_ptr->zbuffer_list->output;
1123 uInt size = png_ptr->zbuffer_size - png_ptr->zstream.avail_out;
1124
1125 #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
1126 if ((png_ptr->mode & PNG_HAVE_IDAT) == 0 &&
1127 png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
1128 optimize_cmf(data, png_image_size(png_ptr));
1129 #endif
1130
1131 png_write_complete_chunk(png_ptr, png_IDAT, data, size);
1132 png_ptr->zstream.avail_out = 0;
1133 png_ptr->zstream.next_out = NULL;
1134 png_ptr->mode |= PNG_HAVE_IDAT | PNG_AFTER_IDAT;
1135
1136 png_ptr->zowner = 0; /* Release the stream */
1137 return;
1138 }
1139
1140 else
1141 {
1142 /* This is an error condition. */
1143 png_zstream_error(png_ptr, ret);
1144 png_error(png_ptr, png_ptr->zstream.msg);
1145 }
1146 }
1147 }
1148
1149 /* Write an IEND chunk */
1150 void /* PRIVATE */
1151 png_write_IEND(png_structrp png_ptr)
1152 {
1153 png_debug(1, "in png_write_IEND");
1154
1155 png_write_complete_chunk(png_ptr, png_IEND, NULL, (png_size_t)0);
1156 png_ptr->mode |= PNG_HAVE_IEND;
1157 }
1158
1159 #ifdef PNG_WRITE_gAMA_SUPPORTED
1160 /* Write a gAMA chunk */
1161 void /* PRIVATE */
1162 png_write_gAMA_fixed(png_structrp png_ptr, png_fixed_point file_gamma)
1163 {
1164 png_byte buf[4];
1165
1166 png_debug(1, "in png_write_gAMA");
1167
1168 /* file_gamma is saved in 1/100,000ths */
1169 png_save_uint_32(buf, (png_uint_32)file_gamma);
1170 png_write_complete_chunk(png_ptr, png_gAMA, buf, (png_size_t)4);
1171 }
1172 #endif
1173
1174 #ifdef PNG_WRITE_sRGB_SUPPORTED
1175 /* Write a sRGB chunk */
1176 void /* PRIVATE */
1177 png_write_sRGB(png_structrp png_ptr, int srgb_intent)
1178 {
1179 png_byte buf[1];
1180
1181 png_debug(1, "in png_write_sRGB");
1182
1183 if (srgb_intent >= PNG_sRGB_INTENT_LAST)
1184 png_warning(png_ptr,
1185 "Invalid sRGB rendering intent specified");
1186
1187 buf[0]=(png_byte)srgb_intent;
1188 png_write_complete_chunk(png_ptr, png_sRGB, buf, (png_size_t)1);
1189 }
1190 #endif
1191
1192 #ifdef PNG_WRITE_iCCP_SUPPORTED
1193 /* Write an iCCP chunk */
1194 void /* PRIVATE */
1195 png_write_iCCP(png_structrp png_ptr, png_const_charp name,
1196 png_const_bytep profile)
1197 {
1198 png_uint_32 name_len;
1199 png_uint_32 profile_len;
1200 png_byte new_name[81]; /* 1 byte for the compression byte */
1201 compression_state comp;
1202 png_uint_32 temp;
1203
1204 png_debug(1, "in png_write_iCCP");
1205
1206 /* These are all internal problems: the profile should have been checked
1207 * before when it was stored.
1208 */
1209 if (profile == NULL)
1210 png_error(png_ptr, "No profile for iCCP chunk"); /* internal error */
1211
1212 profile_len = png_get_uint_32(profile);
1213
1214 if (profile_len < 132)
1215 png_error(png_ptr, "ICC profile too short");
1216
1217 temp = (png_uint_32) (*(profile+8));
1218 if (temp > 3 && (profile_len & 0x03))
1219 png_error(png_ptr, "ICC profile length invalid (not a multiple of 4)");
1220
1221 {
1222 png_uint_32 embedded_profile_len = png_get_uint_32(profile);
1223
1224 if (profile_len != embedded_profile_len)
1225 png_error(png_ptr, "Profile length does not match profile");
1226 }
1227
1228 name_len = png_check_keyword(png_ptr, name, new_name);
1229
1230 if (name_len == 0)
1231 png_error(png_ptr, "iCCP: invalid keyword");
1232
1233 new_name[++name_len] = PNG_COMPRESSION_TYPE_BASE;
1234
1235 /* Make sure we include the NULL after the name and the compression type */
1236 ++name_len;
1237
1238 png_text_compress_init(&comp, profile, profile_len);
1239
1240 /* Allow for keyword terminator and compression byte */
1241 if (png_text_compress(png_ptr, png_iCCP, &comp, name_len) != Z_OK)
1242 png_error(png_ptr, png_ptr->zstream.msg);
1243
1244 png_write_chunk_header(png_ptr, png_iCCP, name_len + comp.output_len);
1245
1246 png_write_chunk_data(png_ptr, new_name, name_len);
1247
1248 png_write_compressed_data_out(png_ptr, &comp);
1249
1250 png_write_chunk_end(png_ptr);
1251 }
1252 #endif
1253
1254 #ifdef PNG_WRITE_sPLT_SUPPORTED
1255 /* Write a sPLT chunk */
1256 void /* PRIVATE */
1257 png_write_sPLT(png_structrp png_ptr, png_const_sPLT_tp spalette)
1258 {
1259 png_uint_32 name_len;
1260 png_byte new_name[80];
1261 png_byte entrybuf[10];
1262 png_size_t entry_size = (spalette->depth == 8 ? 6 : 10);
1263 png_size_t palette_size = entry_size * spalette->nentries;
1264 png_sPLT_entryp ep;
1265 #ifndef PNG_POINTER_INDEXING_SUPPORTED
1266 int i;
1267 #endif
1268
1269 png_debug(1, "in png_write_sPLT");
1270
1271 name_len = png_check_keyword(png_ptr, spalette->name, new_name);
1272
1273 if (name_len == 0)
1274 png_error(png_ptr, "sPLT: invalid keyword");
1275
1276 /* Make sure we include the NULL after the name */
1277 png_write_chunk_header(png_ptr, png_sPLT,
1278 (png_uint_32)(name_len + 2 + palette_size));
1279
1280 png_write_chunk_data(png_ptr, (png_bytep)new_name,
1281 (png_size_t)(name_len + 1));
1282
1283 png_write_chunk_data(png_ptr, &spalette->depth, (png_size_t)1);
1284
1285 /* Loop through each palette entry, writing appropriately */
1286 #ifdef PNG_POINTER_INDEXING_SUPPORTED
1287 for (ep = spalette->entries; ep<spalette->entries + spalette->nentries; ep++)
1288 {
1289 if (spalette->depth == 8)
1290 {
1291 entrybuf[0] = (png_byte)ep->red;
1292 entrybuf[1] = (png_byte)ep->green;
1293 entrybuf[2] = (png_byte)ep->blue;
1294 entrybuf[3] = (png_byte)ep->alpha;
1295 png_save_uint_16(entrybuf + 4, ep->frequency);
1296 }
1297
1298 else
1299 {
1300 png_save_uint_16(entrybuf + 0, ep->red);
1301 png_save_uint_16(entrybuf + 2, ep->green);
1302 png_save_uint_16(entrybuf + 4, ep->blue);
1303 png_save_uint_16(entrybuf + 6, ep->alpha);
1304 png_save_uint_16(entrybuf + 8, ep->frequency);
1305 }
1306
1307 png_write_chunk_data(png_ptr, entrybuf, entry_size);
1308 }
1309 #else
1310 ep=spalette->entries;
1311 for (i = 0; i>spalette->nentries; i++)
1312 {
1313 if (spalette->depth == 8)
1314 {
1315 entrybuf[0] = (png_byte)ep[i].red;
1316 entrybuf[1] = (png_byte)ep[i].green;
1317 entrybuf[2] = (png_byte)ep[i].blue;
1318 entrybuf[3] = (png_byte)ep[i].alpha;
1319 png_save_uint_16(entrybuf + 4, ep[i].frequency);
1320 }
1321
1322 else
1323 {
1324 png_save_uint_16(entrybuf + 0, ep[i].red);
1325 png_save_uint_16(entrybuf + 2, ep[i].green);
1326 png_save_uint_16(entrybuf + 4, ep[i].blue);
1327 png_save_uint_16(entrybuf + 6, ep[i].alpha);
1328 png_save_uint_16(entrybuf + 8, ep[i].frequency);
1329 }
1330
1331 png_write_chunk_data(png_ptr, entrybuf, entry_size);
1332 }
1333 #endif
1334
1335 png_write_chunk_end(png_ptr);
1336 }
1337 #endif
1338
1339 #ifdef PNG_WRITE_sBIT_SUPPORTED
1340 /* Write the sBIT chunk */
1341 void /* PRIVATE */
1342 png_write_sBIT(png_structrp png_ptr, png_const_color_8p sbit, int color_type)
1343 {
1344 png_byte buf[4];
1345 png_size_t size;
1346
1347 png_debug(1, "in png_write_sBIT");
1348
1349 /* Make sure we don't depend upon the order of PNG_COLOR_8 */
1350 if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
1351 {
1352 png_byte maxbits;
1353
1354 maxbits = (png_byte)(color_type==PNG_COLOR_TYPE_PALETTE ? 8 :
1355 png_ptr->usr_bit_depth);
1356
1357 if (sbit->red == 0 || sbit->red > maxbits ||
1358 sbit->green == 0 || sbit->green > maxbits ||
1359 sbit->blue == 0 || sbit->blue > maxbits)
1360 {
1361 png_warning(png_ptr, "Invalid sBIT depth specified");
1362 return;
1363 }
1364
1365 buf[0] = sbit->red;
1366 buf[1] = sbit->green;
1367 buf[2] = sbit->blue;
1368 size = 3;
1369 }
1370
1371 else
1372 {
1373 if (sbit->gray == 0 || sbit->gray > png_ptr->usr_bit_depth)
1374 {
1375 png_warning(png_ptr, "Invalid sBIT depth specified");
1376 return;
1377 }
1378
1379 buf[0] = sbit->gray;
1380 size = 1;
1381 }
1382
1383 if ((color_type & PNG_COLOR_MASK_ALPHA) != 0)
1384 {
1385 if (sbit->alpha == 0 || sbit->alpha > png_ptr->usr_bit_depth)
1386 {
1387 png_warning(png_ptr, "Invalid sBIT depth specified");
1388 return;
1389 }
1390
1391 buf[size++] = sbit->alpha;
1392 }
1393
1394 png_write_complete_chunk(png_ptr, png_sBIT, buf, size);
1395 }
1396 #endif
1397
1398 #ifdef PNG_WRITE_cHRM_SUPPORTED
1399 /* Write the cHRM chunk */
1400 void /* PRIVATE */
1401 png_write_cHRM_fixed(png_structrp png_ptr, const png_xy *xy)
1402 {
1403 png_byte buf[32];
1404
1405 png_debug(1, "in png_write_cHRM");
1406
1407 /* Each value is saved in 1/100,000ths */
1408 png_save_int_32(buf, xy->whitex);
1409 png_save_int_32(buf + 4, xy->whitey);
1410
1411 png_save_int_32(buf + 8, xy->redx);
1412 png_save_int_32(buf + 12, xy->redy);
1413
1414 png_save_int_32(buf + 16, xy->greenx);
1415 png_save_int_32(buf + 20, xy->greeny);
1416
1417 png_save_int_32(buf + 24, xy->bluex);
1418 png_save_int_32(buf + 28, xy->bluey);
1419
1420 png_write_complete_chunk(png_ptr, png_cHRM, buf, 32);
1421 }
1422 #endif
1423
1424 #ifdef PNG_WRITE_tRNS_SUPPORTED
1425 /* Write the tRNS chunk */
1426 void /* PRIVATE */
1427 png_write_tRNS(png_structrp png_ptr, png_const_bytep trans_alpha,
1428 png_const_color_16p tran, int num_trans, int color_type)
1429 {
1430 png_byte buf[6];
1431
1432 png_debug(1, "in png_write_tRNS");
1433
1434 if (color_type == PNG_COLOR_TYPE_PALETTE)
1435 {
1436 if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette)
1437 {
1438 png_app_warning(png_ptr,
1439 "Invalid number of transparent colors specified");
1440 return;
1441 }
1442
1443 /* Write the chunk out as it is */
1444 png_write_complete_chunk(png_ptr, png_tRNS, trans_alpha,
1445 (png_size_t)num_trans);
1446 }
1447
1448 else if (color_type == PNG_COLOR_TYPE_GRAY)
1449 {
1450 /* One 16-bit value */
1451 if (tran->gray >= (1 << png_ptr->bit_depth))
1452 {
1453 png_app_warning(png_ptr,
1454 "Ignoring attempt to write tRNS chunk out-of-range for bit_depth");
1455
1456 return;
1457 }
1458
1459 png_save_uint_16(buf, tran->gray);
1460 png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)2);
1461 }
1462
1463 else if (color_type == PNG_COLOR_TYPE_RGB)
1464 {
1465 /* Three 16-bit values */
1466 png_save_uint_16(buf, tran->red);
1467 png_save_uint_16(buf + 2, tran->green);
1468 png_save_uint_16(buf + 4, tran->blue);
1469 #ifdef PNG_WRITE_16BIT_SUPPORTED
1470 if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]) != 0)
1471 #else
1472 if ((buf[0] | buf[2] | buf[4]) != 0)
1473 #endif
1474 {
1475 png_app_warning(png_ptr,
1476 "Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8");
1477 return;
1478 }
1479
1480 png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)6);
1481 }
1482
1483 else
1484 {
1485 png_app_warning(png_ptr, "Can't write tRNS with an alpha channel");
1486 }
1487 }
1488 #endif
1489
1490 #ifdef PNG_WRITE_bKGD_SUPPORTED
1491 /* Write the background chunk */
1492 void /* PRIVATE */
1493 png_write_bKGD(png_structrp png_ptr, png_const_color_16p back, int color_type)
1494 {
1495 png_byte buf[6];
1496
1497 png_debug(1, "in png_write_bKGD");
1498
1499 if (color_type == PNG_COLOR_TYPE_PALETTE)
1500 {
1501 if (
1502 #ifdef PNG_MNG_FEATURES_SUPPORTED
1503 (png_ptr->num_palette != 0 ||
1504 (png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0) &&
1505 #endif
1506 back->index >= png_ptr->num_palette)
1507 {
1508 png_warning(png_ptr, "Invalid background palette index");
1509 return;
1510 }
1511
1512 buf[0] = back->index;
1513 png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)1);
1514 }
1515
1516 else if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
1517 {
1518 png_save_uint_16(buf, back->red);
1519 png_save_uint_16(buf + 2, back->green);
1520 png_save_uint_16(buf + 4, back->blue);
1521 #ifdef PNG_WRITE_16BIT_SUPPORTED
1522 if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]) != 0)
1523 #else
1524 if ((buf[0] | buf[2] | buf[4]) != 0)
1525 #endif
1526 {
1527 png_warning(png_ptr,
1528 "Ignoring attempt to write 16-bit bKGD chunk when bit_depth is 8");
1529
1530 return;
1531 }
1532
1533 png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)6);
1534 }
1535
1536 else
1537 {
1538 if (back->gray >= (1 << png_ptr->bit_depth))
1539 {
1540 png_warning(png_ptr,
1541 "Ignoring attempt to write bKGD chunk out-of-range for bit_depth");
1542
1543 return;
1544 }
1545
1546 png_save_uint_16(buf, back->gray);
1547 png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)2);
1548 }
1549 }
1550 #endif
1551
1552 #ifdef PNG_WRITE_hIST_SUPPORTED
1553 /* Write the histogram */
1554 void /* PRIVATE */
1555 png_write_hIST(png_structrp png_ptr, png_const_uint_16p hist, int num_hist)
1556 {
1557 int i;
1558 png_byte buf[3];
1559
1560 png_debug(1, "in png_write_hIST");
1561
1562 if (num_hist > (int)png_ptr->num_palette)
1563 {
1564 png_debug2(3, "num_hist = %d, num_palette = %d", num_hist,
1565 png_ptr->num_palette);
1566
1567 png_warning(png_ptr, "Invalid number of histogram entries specified");
1568 return;
1569 }
1570
1571 png_write_chunk_header(png_ptr, png_hIST, (png_uint_32)(num_hist * 2));
1572
1573 for (i = 0; i < num_hist; i++)
1574 {
1575 png_save_uint_16(buf, hist[i]);
1576 png_write_chunk_data(png_ptr, buf, (png_size_t)2);
1577 }
1578
1579 png_write_chunk_end(png_ptr);
1580 }
1581 #endif
1582
1583 #ifdef PNG_WRITE_tEXt_SUPPORTED
1584 /* Write a tEXt chunk */
1585 void /* PRIVATE */
1586 png_write_tEXt(png_structrp png_ptr, png_const_charp key, png_const_charp text,
1587 png_size_t text_len)
1588 {
1589 png_uint_32 key_len;
1590 png_byte new_key[80];
1591
1592 png_debug(1, "in png_write_tEXt");
1593
1594 key_len = png_check_keyword(png_ptr, key, new_key);
1595
1596 if (key_len == 0)
1597 png_error(png_ptr, "tEXt: invalid keyword");
1598
1599 if (text == NULL || *text == '\0')
1600 text_len = 0;
1601
1602 else
1603 text_len = strlen(text);
1604
1605 if (text_len > PNG_UINT_31_MAX - (key_len+1))
1606 png_error(png_ptr, "tEXt: text too long");
1607
1608 /* Make sure we include the 0 after the key */
1609 png_write_chunk_header(png_ptr, png_tEXt,
1610 (png_uint_32)/*checked above*/(key_len + text_len + 1));
1611 /*
1612 * We leave it to the application to meet PNG-1.0 requirements on the
1613 * contents of the text. PNG-1.0 through PNG-1.2 discourage the use of
1614 * any non-Latin-1 characters except for NEWLINE. ISO PNG will forbid them.
1615 * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1616 */
1617 png_write_chunk_data(png_ptr, new_key, key_len + 1);
1618
1619 if (text_len != 0)
1620 png_write_chunk_data(png_ptr, (png_const_bytep)text, text_len);
1621
1622 png_write_chunk_end(png_ptr);
1623 }
1624 #endif
1625
1626 #ifdef PNG_WRITE_zTXt_SUPPORTED
1627 /* Write a compressed text chunk */
1628 void /* PRIVATE */
1629 png_write_zTXt(png_structrp png_ptr, png_const_charp key, png_const_charp text,
1630 int compression)
1631 {
1632 png_uint_32 key_len;
1633 png_byte new_key[81];
1634 compression_state comp;
1635
1636 png_debug(1, "in png_write_zTXt");
1637
1638 if (compression == PNG_TEXT_COMPRESSION_NONE)
1639 {
1640 png_write_tEXt(png_ptr, key, text, 0);
1641 return;
1642 }
1643
1644 if (compression != PNG_TEXT_COMPRESSION_zTXt)
1645 png_error(png_ptr, "zTXt: invalid compression type");
1646
1647 key_len = png_check_keyword(png_ptr, key, new_key);
1648
1649 if (key_len == 0)
1650 png_error(png_ptr, "zTXt: invalid keyword");
1651
1652 /* Add the compression method and 1 for the keyword separator. */
1653 new_key[++key_len] = PNG_COMPRESSION_TYPE_BASE;
1654 ++key_len;
1655
1656 /* Compute the compressed data; do it now for the length */
1657 png_text_compress_init(&comp, (png_const_bytep)text,
1658 text == NULL ? 0 : strlen(text));
1659
1660 if (png_text_compress(png_ptr, png_zTXt, &comp, key_len) != Z_OK)
1661 png_error(png_ptr, png_ptr->zstream.msg);
1662
1663 /* Write start of chunk */
1664 png_write_chunk_header(png_ptr, png_zTXt, key_len + comp.output_len);
1665
1666 /* Write key */
1667 png_write_chunk_data(png_ptr, new_key, key_len);
1668
1669 /* Write the compressed data */
1670 png_write_compressed_data_out(png_ptr, &comp);
1671
1672 /* Close the chunk */
1673 png_write_chunk_end(png_ptr);
1674 }
1675 #endif
1676
1677 #ifdef PNG_WRITE_iTXt_SUPPORTED
1678 /* Write an iTXt chunk */
1679 void /* PRIVATE */
1680 png_write_iTXt(png_structrp png_ptr, int compression, png_const_charp key,
1681 png_const_charp lang, png_const_charp lang_key, png_const_charp text)
1682 {
1683 png_uint_32 key_len, prefix_len;
1684 png_size_t lang_len, lang_key_len;
1685 png_byte new_key[82];
1686 compression_state comp;
1687
1688 png_debug(1, "in png_write_iTXt");
1689
1690 key_len = png_check_keyword(png_ptr, key, new_key);
1691
1692 if (key_len == 0)
1693 png_error(png_ptr, "iTXt: invalid keyword");
1694
1695 /* Set the compression flag */
1696 switch (compression)
1697 {
1698 case PNG_ITXT_COMPRESSION_NONE:
1699 case PNG_TEXT_COMPRESSION_NONE:
1700 compression = new_key[++key_len] = 0; /* no compression */
1701 break;
1702
1703 case PNG_TEXT_COMPRESSION_zTXt:
1704 case PNG_ITXT_COMPRESSION_zTXt:
1705 compression = new_key[++key_len] = 1; /* compressed */
1706 break;
1707
1708 default:
1709 png_error(png_ptr, "iTXt: invalid compression");
1710 }
1711
1712 new_key[++key_len] = PNG_COMPRESSION_TYPE_BASE;
1713 ++key_len; /* for the keywod separator */
1714
1715 /* We leave it to the application to meet PNG-1.0 requirements on the
1716 * contents of the text. PNG-1.0 through PNG-1.2 discourage the use of
1717 * any non-Latin-1 characters except for NEWLINE. ISO PNG, however,
1718 * specifies that the text is UTF-8 and this really doesn't require any
1719 * checking.
1720 *
1721 * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1722 *
1723 * TODO: validate the language tag correctly (see the spec.)
1724 */
1725 if (lang == NULL) lang = ""; /* empty language is valid */
1726 lang_len = strlen(lang)+1;
1727 if (lang_key == NULL) lang_key = ""; /* may be empty */
1728 lang_key_len = strlen(lang_key)+1;
1729 if (text == NULL) text = ""; /* may be empty */
1730
1731 prefix_len = key_len;
1732 if (lang_len > PNG_UINT_31_MAX-prefix_len)
1733 prefix_len = PNG_UINT_31_MAX;
1734 else
1735 prefix_len = (png_uint_32)(prefix_len + lang_len);
1736
1737 if (lang_key_len > PNG_UINT_31_MAX-prefix_len)
1738 prefix_len = PNG_UINT_31_MAX;
1739 else
1740 prefix_len = (png_uint_32)(prefix_len + lang_key_len);
1741
1742 png_text_compress_init(&comp, (png_const_bytep)text, strlen(text));
1743
1744 if (compression != 0)
1745 {
1746 if (png_text_compress(png_ptr, png_iTXt, &comp, prefix_len) != Z_OK)
1747 png_error(png_ptr, png_ptr->zstream.msg);
1748 }
1749
1750 else
1751 {
1752 if (comp.input_len > PNG_UINT_31_MAX-prefix_len)
1753 png_error(png_ptr, "iTXt: uncompressed text too long");
1754
1755 /* So the string will fit in a chunk: */
1756 comp.output_len = (png_uint_32)/*SAFE*/comp.input_len;
1757 }
1758
1759 png_write_chunk_header(png_ptr, png_iTXt, comp.output_len + prefix_len);
1760
1761 png_write_chunk_data(png_ptr, new_key, key_len);
1762
1763 png_write_chunk_data(png_ptr, (png_const_bytep)lang, lang_len);
1764
1765 png_write_chunk_data(png_ptr, (png_const_bytep)lang_key, lang_key_len);
1766
1767 if (compression != 0)
1768 png_write_compressed_data_out(png_ptr, &comp);
1769
1770 else
1771 png_write_chunk_data(png_ptr, (png_const_bytep)text, comp.output_len);
1772
1773 png_write_chunk_end(png_ptr);
1774 }
1775 #endif
1776
1777 #ifdef PNG_WRITE_oFFs_SUPPORTED
1778 /* Write the oFFs chunk */
1779 void /* PRIVATE */
1780 png_write_oFFs(png_structrp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
1781 int unit_type)
1782 {
1783 png_byte buf[9];
1784
1785 png_debug(1, "in png_write_oFFs");
1786
1787 if (unit_type >= PNG_OFFSET_LAST)
1788 png_warning(png_ptr, "Unrecognized unit type for oFFs chunk");
1789
1790 png_save_int_32(buf, x_offset);
1791 png_save_int_32(buf + 4, y_offset);
1792 buf[8] = (png_byte)unit_type;
1793
1794 png_write_complete_chunk(png_ptr, png_oFFs, buf, (png_size_t)9);
1795 }
1796 #endif
1797 #ifdef PNG_WRITE_pCAL_SUPPORTED
1798 /* Write the pCAL chunk (described in the PNG extensions document) */
1799 void /* PRIVATE */
1800 png_write_pCAL(png_structrp png_ptr, png_charp purpose, png_int_32 X0,
1801 png_int_32 X1, int type, int nparams, png_const_charp units,
1802 png_charpp params)
1803 {
1804 png_uint_32 purpose_len;
1805 png_size_t units_len, total_len;
1806 png_size_tp params_len;
1807 png_byte buf[10];
1808 png_byte new_purpose[80];
1809 int i;
1810
1811 png_debug1(1, "in png_write_pCAL (%d parameters)", nparams);
1812
1813 if (type >= PNG_EQUATION_LAST)
1814 png_error(png_ptr, "Unrecognized equation type for pCAL chunk");
1815
1816 purpose_len = png_check_keyword(png_ptr, purpose, new_purpose);
1817
1818 if (purpose_len == 0)
1819 png_error(png_ptr, "pCAL: invalid keyword");
1820
1821 ++purpose_len; /* terminator */
1822
1823 png_debug1(3, "pCAL purpose length = %d", (int)purpose_len);
1824 units_len = strlen(units) + (nparams == 0 ? 0 : 1);
1825 png_debug1(3, "pCAL units length = %d", (int)units_len);
1826 total_len = purpose_len + units_len + 10;
1827
1828 params_len = (png_size_tp)png_malloc(png_ptr,
1829 (png_alloc_size_t)(nparams * (sizeof (png_size_t))));
1830
1831 /* Find the length of each parameter, making sure we don't count the
1832 * null terminator for the last parameter.
1833 */
1834 for (i = 0; i < nparams; i++)
1835 {
1836 params_len[i] = strlen(params[i]) + (i == nparams - 1 ? 0 : 1);
1837 png_debug2(3, "pCAL parameter %d length = %lu", i,
1838 (unsigned long)params_len[i]);
1839 total_len += params_len[i];
1840 }
1841
1842 png_debug1(3, "pCAL total length = %d", (int)total_len);
1843 png_write_chunk_header(png_ptr, png_pCAL, (png_uint_32)total_len);
1844 png_write_chunk_data(png_ptr, new_purpose, purpose_len);
1845 png_save_int_32(buf, X0);
1846 png_save_int_32(buf + 4, X1);
1847 buf[8] = (png_byte)type;
1848 buf[9] = (png_byte)nparams;
1849 png_write_chunk_data(png_ptr, buf, (png_size_t)10);
1850 png_write_chunk_data(png_ptr, (png_const_bytep)units, (png_size_t)units_len);
1851
1852 for (i = 0; i < nparams; i++)
1853 {
1854 png_write_chunk_data(png_ptr, (png_const_bytep)params[i], params_len[i]);
1855 }
1856
1857 png_free(png_ptr, params_len);
1858 png_write_chunk_end(png_ptr);
1859 }
1860 #endif
1861
1862 #ifdef PNG_WRITE_sCAL_SUPPORTED
1863 /* Write the sCAL chunk */
1864 void /* PRIVATE */
1865 png_write_sCAL_s(png_structrp png_ptr, int unit, png_const_charp width,
1866 png_const_charp height)
1867 {
1868 png_byte buf[64];
1869 png_size_t wlen, hlen, total_len;
1870
1871 png_debug(1, "in png_write_sCAL_s");
1872
1873 wlen = strlen(width);
1874 hlen = strlen(height);
1875 total_len = wlen + hlen + 2;
1876
1877 if (total_len > 64)
1878 {
1879 png_warning(png_ptr, "Can't write sCAL (buffer too small)");
1880 return;
1881 }
1882
1883 buf[0] = (png_byte)unit;
1884 memcpy(buf + 1, width, wlen + 1); /* Append the '\0' here */
1885 memcpy(buf + wlen + 2, height, hlen); /* Do NOT append the '\0' here */
1886
1887 png_debug1(3, "sCAL total length = %u", (unsigned int)total_len);
1888 png_write_complete_chunk(png_ptr, png_sCAL, buf, total_len);
1889 }
1890 #endif
1891
1892 #ifdef PNG_WRITE_pHYs_SUPPORTED
1893 /* Write the pHYs chunk */
1894 void /* PRIVATE */
1895 png_write_pHYs(png_structrp png_ptr, png_uint_32 x_pixels_per_unit,
1896 png_uint_32 y_pixels_per_unit,
1897 int unit_type)
1898 {
1899 png_byte buf[9];
1900
1901 png_debug(1, "in png_write_pHYs");
1902
1903 if (unit_type >= PNG_RESOLUTION_LAST)
1904 png_warning(png_ptr, "Unrecognized unit type for pHYs chunk");
1905
1906 png_save_uint_32(buf, x_pixels_per_unit);
1907 png_save_uint_32(buf + 4, y_pixels_per_unit);
1908 buf[8] = (png_byte)unit_type;
1909
1910 png_write_complete_chunk(png_ptr, png_pHYs, buf, (png_size_t)9);
1911 }
1912 #endif
1913
1914 #ifdef PNG_WRITE_tIME_SUPPORTED
1915 /* Write the tIME chunk. Use either png_convert_from_struct_tm()
1916 * or png_convert_from_time_t(), or fill in the structure yourself.
1917 */
1918 void /* PRIVATE */
1919 png_write_tIME(png_structrp png_ptr, png_const_timep mod_time)
1920 {
1921 png_byte buf[7];
1922
1923 png_debug(1, "in png_write_tIME");
1924
1925 if (mod_time->month > 12 || mod_time->month < 1 ||
1926 mod_time->day > 31 || mod_time->day < 1 ||
1927 mod_time->hour > 23 || mod_time->second > 60)
1928 {
1929 png_warning(png_ptr, "Invalid time specified for tIME chunk");
1930 return;
1931 }
1932
1933 png_save_uint_16(buf, mod_time->year);
1934 buf[2] = mod_time->month;
1935 buf[3] = mod_time->day;
1936 buf[4] = mod_time->hour;
1937 buf[5] = mod_time->minute;
1938 buf[6] = mod_time->second;
1939
1940 png_write_complete_chunk(png_ptr, png_tIME, buf, (png_size_t)7);
1941 }
1942 #endif
1943
1944 /* Initializes the row writing capability of libpng */
1945 void /* PRIVATE */
1946 png_write_start_row(png_structrp png_ptr)
1947 {
1948 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
1949 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1950
1951 /* Start of interlace block */
1952 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
1953
1954 /* Offset to next interlace block */
1955 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
1956
1957 /* Start of interlace block in the y direction */
1958 static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
1959
1960 /* Offset to next interlace block in the y direction */
1961 static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
1962 #endif
1963
1964 png_alloc_size_t buf_size;
1965 int usr_pixel_depth;
1966
1967 #ifdef PNG_WRITE_FILTER_SUPPORTED
1968 png_byte filters;
1969 #endif
1970
1971 png_debug(1, "in png_write_start_row");
1972
1973 usr_pixel_depth = png_ptr->usr_channels * png_ptr->usr_bit_depth;
1974 buf_size = PNG_ROWBYTES(usr_pixel_depth, png_ptr->width) + 1;
1975
1976 /* 1.5.6: added to allow checking in the row write code. */
1977 png_ptr->transformed_pixel_depth = png_ptr->pixel_depth;
1978 png_ptr->maximum_pixel_depth = (png_byte)usr_pixel_depth;
1979
1980 /* Set up row buffer */
1981 png_ptr->row_buf = png_voidcast(png_bytep, png_malloc(png_ptr, buf_size));
1982
1983 png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE;
1984
1985 #ifdef PNG_WRITE_FILTER_SUPPORTED
1986 filters = png_ptr->do_filter;
1987
1988 if (png_ptr->height == 1)
1989 filters &= 0xff & ~(PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH);
1990
1991 if (png_ptr->width == 1)
1992 filters &= 0xff & ~(PNG_FILTER_SUB|PNG_FILTER_AVG|PNG_FILTER_PAETH);
1993
1994 if (filters == 0)
1995 filters = PNG_FILTER_NONE;
1996
1997 png_ptr->do_filter = filters;
1998
1999 if (((filters & (PNG_FILTER_SUB | PNG_FILTER_UP | PNG_FILTER_AVG |
2000 PNG_FILTER_PAETH)) != 0) && png_ptr->try_row == NULL)
2001 {
2002 int num_filters = 0;
2003
2004 png_ptr->try_row = png_voidcast(png_bytep, png_malloc(png_ptr, buf_size));
2005
2006 if (filters & PNG_FILTER_SUB)
2007 num_filters++;
2008
2009 if (filters & PNG_FILTER_UP)
2010 num_filters++;
2011
2012 if (filters & PNG_FILTER_AVG)
2013 num_filters++;
2014
2015 if (filters & PNG_FILTER_PAETH)
2016 num_filters++;
2017
2018 if (num_filters > 1)
2019 png_ptr->tst_row = png_voidcast(png_bytep, png_malloc(png_ptr,
2020 buf_size));
2021 }
2022
2023 /* We only need to keep the previous row if we are using one of the following
2024 * filters.
2025 */
2026 if ((filters & (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH)) != 0)
2027 png_ptr->prev_row = png_voidcast(png_bytep,
2028 png_calloc(png_ptr, buf_size));
2029 #endif /* WRITE_FILTER */
2030
2031 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
2032 /* If interlaced, we need to set up width and height of pass */
2033 if (png_ptr->interlaced != 0)
2034 {
2035 if ((png_ptr->transformations & PNG_INTERLACE) == 0)
2036 {
2037 png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
2038 png_pass_ystart[0]) / png_pass_yinc[0];
2039
2040 png_ptr->usr_width = (png_ptr->width + png_pass_inc[0] - 1 -
2041 png_pass_start[0]) / png_pass_inc[0];
2042 }
2043
2044 else
2045 {
2046 png_ptr->num_rows = png_ptr->height;
2047 png_ptr->usr_width = png_ptr->width;
2048 }
2049 }
2050
2051 else
2052 #endif
2053 {
2054 png_ptr->num_rows = png_ptr->height;
2055 png_ptr->usr_width = png_ptr->width;
2056 }
2057 }
2058
2059 /* Internal use only. Called when finished processing a row of data. */
2060 void /* PRIVATE */
2061 png_write_finish_row(png_structrp png_ptr)
2062 {
2063 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
2064 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
2065
2066 /* Start of interlace block */
2067 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
2068
2069 /* Offset to next interlace block */
2070 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
2071
2072 /* Start of interlace block in the y direction */
2073 static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
2074
2075 /* Offset to next interlace block in the y direction */
2076 static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
2077 #endif
2078
2079 png_debug(1, "in png_write_finish_row");
2080
2081 /* Next row */
2082 png_ptr->row_number++;
2083
2084 /* See if we are done */
2085 if (png_ptr->row_number < png_ptr->num_rows)
2086 return;
2087
2088 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
2089 /* If interlaced, go to next pass */
2090 if (png_ptr->interlaced != 0)
2091 {
2092 png_ptr->row_number = 0;
2093 if ((png_ptr->transformations & PNG_INTERLACE) != 0)
2094 {
2095 png_ptr->pass++;
2096 }
2097
2098 else
2099 {
2100 /* Loop until we find a non-zero width or height pass */
2101 do
2102 {
2103 png_ptr->pass++;
2104
2105 if (png_ptr->pass >= 7)
2106 break;
2107
2108 png_ptr->usr_width = (png_ptr->width +
2109 png_pass_inc[png_ptr->pass] - 1 -
2110 png_pass_start[png_ptr->pass]) /
2111 png_pass_inc[png_ptr->pass];
2112
2113 png_ptr->num_rows = (png_ptr->height +
2114 png_pass_yinc[png_ptr->pass] - 1 -
2115 png_pass_ystart[png_ptr->pass]) /
2116 png_pass_yinc[png_ptr->pass];
2117
2118 if ((png_ptr->transformations & PNG_INTERLACE) != 0)
2119 break;
2120
2121 } while (png_ptr->usr_width == 0 || png_ptr->num_rows == 0);
2122
2123 }
2124
2125 /* Reset the row above the image for the next pass */
2126 if (png_ptr->pass < 7)
2127 {
2128 if (png_ptr->prev_row != NULL)
2129 memset(png_ptr->prev_row, 0,
2130 (png_size_t)(PNG_ROWBYTES(png_ptr->usr_channels*
2131 png_ptr->usr_bit_depth, png_ptr->width)) + 1);
2132
2133 return;
2134 }
2135 }
2136 #endif
2137
2138 /* If we get here, we've just written the last row, so we need
2139 to flush the compressor */
2140 png_compress_IDAT(png_ptr, NULL, 0, Z_FINISH);
2141 }
2142
2143 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
2144 /* Pick out the correct pixels for the interlace pass.
2145 * The basic idea here is to go through the row with a source
2146 * pointer and a destination pointer (sp and dp), and copy the
2147 * correct pixels for the pass. As the row gets compacted,
2148 * sp will always be >= dp, so we should never overwrite anything.
2149 * See the default: case for the easiest code to understand.
2150 */
2151 void /* PRIVATE */
2152 png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
2153 {
2154 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
2155
2156 /* Start of interlace block */
2157 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
2158
2159 /* Offset to next interlace block */
2160 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
2161
2162 png_debug(1, "in png_do_write_interlace");
2163
2164 /* We don't have to do anything on the last pass (6) */
2165 if (pass < 6)
2166 {
2167 /* Each pixel depth is handled separately */
2168 switch (row_info->pixel_depth)
2169 {
2170 case 1:
2171 {
2172 png_bytep sp;
2173 png_bytep dp;
2174 unsigned int shift;
2175 int d;
2176 int value;
2177 png_uint_32 i;
2178 png_uint_32 row_width = row_info->width;
2179
2180 dp = row;
2181 d = 0;
2182 shift = 7;
2183
2184 for (i = png_pass_start[pass]; i < row_width;
2185 i += png_pass_inc[pass])
2186 {
2187 sp = row + (png_size_t)(i >> 3);
2188 value = (int)(*sp >> (7 - (int)(i & 0x07))) & 0x01;
2189 d |= (value << shift);
2190
2191 if (shift == 0)
2192 {
2193 shift = 7;
2194 *dp++ = (png_byte)d;
2195 d = 0;
2196 }
2197
2198 else
2199 shift--;
2200
2201 }
2202 if (shift != 7)
2203 *dp = (png_byte)d;
2204
2205 break;
2206 }
2207
2208 case 2:
2209 {
2210 png_bytep sp;
2211 png_bytep dp;
2212 unsigned int shift;
2213 int d;
2214 int value;
2215 png_uint_32 i;
2216 png_uint_32 row_width = row_info->width;
2217
2218 dp = row;
2219 shift = 6;
2220 d = 0;
2221
2222 for (i = png_pass_start[pass]; i < row_width;
2223 i += png_pass_inc[pass])
2224 {
2225 sp = row + (png_size_t)(i >> 2);
2226 value = (*sp >> ((3 - (int)(i & 0x03)) << 1)) & 0x03;
2227 d |= (value << shift);
2228
2229 if (shift == 0)
2230 {
2231 shift = 6;
2232 *dp++ = (png_byte)d;
2233 d = 0;
2234 }
2235
2236 else
2237 shift -= 2;
2238 }
2239 if (shift != 6)
2240 *dp = (png_byte)d;
2241
2242 break;
2243 }
2244
2245 case 4:
2246 {
2247 png_bytep sp;
2248 png_bytep dp;
2249 unsigned int shift;
2250 int d;
2251 int value;
2252 png_uint_32 i;
2253 png_uint_32 row_width = row_info->width;
2254
2255 dp = row;
2256 shift = 4;
2257 d = 0;
2258 for (i = png_pass_start[pass]; i < row_width;
2259 i += png_pass_inc[pass])
2260 {
2261 sp = row + (png_size_t)(i >> 1);
2262 value = (*sp >> ((1 - (int)(i & 0x01)) << 2)) & 0x0f;
2263 d |= (value << shift);
2264
2265 if (shift == 0)
2266 {
2267 shift = 4;
2268 *dp++ = (png_byte)d;
2269 d = 0;
2270 }
2271
2272 else
2273 shift -= 4;
2274 }
2275 if (shift != 4)
2276 *dp = (png_byte)d;
2277
2278 break;
2279 }
2280
2281 default:
2282 {
2283 png_bytep sp;
2284 png_bytep dp;
2285 png_uint_32 i;
2286 png_uint_32 row_width = row_info->width;
2287 png_size_t pixel_bytes;
2288
2289 /* Start at the beginning */
2290 dp = row;
2291
2292 /* Find out how many bytes each pixel takes up */
2293 pixel_bytes = (row_info->pixel_depth >> 3);
2294
2295 /* Loop through the row, only looking at the pixels that matter */
2296 for (i = png_pass_start[pass]; i < row_width;
2297 i += png_pass_inc[pass])
2298 {
2299 /* Find out where the original pixel is */
2300 sp = row + (png_size_t)i * pixel_bytes;
2301
2302 /* Move the pixel */
2303 if (dp != sp)
2304 memcpy(dp, sp, pixel_bytes);
2305
2306 /* Next pixel */
2307 dp += pixel_bytes;
2308 }
2309 break;
2310 }
2311 }
2312 /* Set new row width */
2313 row_info->width = (row_info->width +
2314 png_pass_inc[pass] - 1 -
2315 png_pass_start[pass]) /
2316 png_pass_inc[pass];
2317
2318 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
2319 row_info->width);
2320 }
2321 }
2322 #endif
2323
2324
2325 /* This filters the row, chooses which filter to use, if it has not already
2326 * been specified by the application, and then writes the row out with the
2327 * chosen filter.
2328 */
2329 static void /* PRIVATE */
2330 png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row,
2331 png_size_t row_bytes);
2332
2333 #ifdef PNG_WRITE_FILTER_SUPPORTED
2334 static png_size_t /* PRIVATE */
2335 png_setup_sub_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, lp;
2339 png_size_t i;
2340 png_size_t sum = 0;
2341 int v;
2342
2343 png_ptr->try_row[0] = PNG_FILTER_VALUE_SUB;
2344
2345 for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1; i < bpp;
2346 i++, rp++, dp++)
2347 {
2348 v = *dp = *rp;
2349 sum += (v < 128) ? v : 256 - v;
2350 }
2351
2352 for (lp = png_ptr->row_buf + 1; i < row_bytes;
2353 i++, rp++, lp++, dp++)
2354 {
2355 v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
2356 sum += (v < 128) ? v : 256 - v;
2357
2358 if (sum > lmins) /* We are already worse, don't continue. */
2359 break;
2360 }
2361
2362 return (sum);
2363 }
2364
2365 static png_size_t /* PRIVATE */
2366 png_setup_up_row(png_structrp png_ptr, const png_size_t row_bytes,
2367 const png_size_t lmins)
2368 {
2369 png_bytep rp, dp, pp;
2370 png_size_t i;
2371 png_size_t sum = 0;
2372 int v;
2373
2374 png_ptr->try_row[0] = PNG_FILTER_VALUE_UP;
2375
2376 for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1,
2377 pp = png_ptr->prev_row + 1; i < row_bytes;
2378 i++, rp++, pp++, dp++)
2379 {
2380 v = *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
2381 sum += (v < 128) ? v : 256 - v;
2382
2383 if (sum > lmins) /* We are already worse, don't continue. */
2384 break;
2385 }
2386
2387 return (sum);
2388 }
2389
2390 static png_size_t /* PRIVATE */
2391 png_setup_avg_row(png_structrp png_ptr, const png_uint_32 bpp,
2392 const png_size_t row_bytes, const png_size_t lmins)
2393 {
2394 png_bytep rp, dp, pp, lp;
2395 png_uint_32 i;
2396 png_size_t sum = 0;
2397 int v;
2398
2399 png_ptr->try_row[0] = PNG_FILTER_VALUE_AVG;
2400
2401 for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1,
2402 pp = png_ptr->prev_row + 1; i < bpp; i++)
2403 {
2404 v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
2405
2406 sum += (v < 128) ? v : 256 - v;
2407 }
2408
2409 for (lp = png_ptr->row_buf + 1; i < row_bytes; i++)
2410 {
2411 v = *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
2412 & 0xff);
2413
2414 sum += (v < 128) ? v : 256 - v;
2415
2416 if (sum > lmins) /* We are already worse, don't continue. */
2417 break;
2418 }
2419
2420 return (sum);
2421 }
2422
2423 static png_size_t /* PRIVATE */
2424 png_setup_paeth_row(png_structrp png_ptr, const png_uint_32 bpp,
2425 const png_size_t row_bytes, const png_size_t lmins)
2426 {
2427 png_bytep rp, dp, pp, cp, lp;
2428 png_size_t i;
2429 png_size_t sum = 0;
2430 int v;
2431
2432 png_ptr->try_row[0] = PNG_FILTER_VALUE_PAETH;
2433
2434 for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1,
2435 pp = png_ptr->prev_row + 1; i < bpp; i++)
2436 {
2437 v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2438
2439 sum += (v < 128) ? v : 256 - v;
2440 }
2441
2442 for (lp = png_ptr->row_buf + 1, cp = png_ptr->prev_row + 1; i < row_bytes;
2443 i++)
2444 {
2445 int a, b, c, pa, pb, pc, p;
2446
2447 b = *pp++;
2448 c = *cp++;
2449 a = *lp++;
2450
2451 p = b - c;
2452 pc = a - c;
2453
2454 #ifdef PNG_USE_ABS
2455 pa = abs(p);
2456 pb = abs(pc);
2457 pc = abs(p + pc);
2458 #else
2459 pa = p < 0 ? -p : p;
2460 pb = pc < 0 ? -pc : pc;
2461 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
2462 #endif
2463
2464 p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
2465
2466 v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
2467
2468 sum += (v < 128) ? v : 256 - v;
2469
2470 if (sum > lmins) /* We are already worse, don't continue. */
2471 break;
2472 }
2473
2474 return (sum);
2475 }
2476 #endif /* WRITE_FILTER */
2477
2478 void /* PRIVATE */
2479 png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
2480 {
2481 #ifndef PNG_WRITE_FILTER_SUPPORTED
2482 png_write_filtered_row(png_ptr, png_ptr->row_buf, row_info->rowbytes+1);
2483 #else
2484 png_byte filter_to_do = png_ptr->do_filter;
2485 png_bytep row_buf;
2486 png_bytep best_row;
2487 png_uint_32 bpp;
2488 png_size_t mins;
2489 png_size_t row_bytes = row_info->rowbytes;
2490
2491 png_debug(1, "in png_write_find_filter");
2492
2493 /* Find out how many bytes offset each pixel is */
2494 bpp = (row_info->pixel_depth + 7) >> 3;
2495
2496 row_buf = png_ptr->row_buf;
2497 mins = PNG_SIZE_MAX - 256/* so we can detect potential overflow of the
2498 running sum */;
2499
2500 /* The prediction method we use is to find which method provides the
2501 * smallest value when summing the absolute values of the distances
2502 * from zero, using anything >= 128 as negative numbers. This is known
2503 * as the "minimum sum of absolute differences" heuristic. Other
2504 * heuristics are the "weighted minimum sum of absolute differences"
2505 * (experimental and can in theory improve compression), and the "zlib
2506 * predictive" method (not implemented yet), which does test compressions
2507 * of lines using different filter methods, and then chooses the
2508 * (series of) filter(s) that give minimum compressed data size (VERY
2509 * computationally expensive).
2510 *
2511 * GRR 980525: consider also
2512 *
2513 * (1) minimum sum of absolute differences from running average (i.e.,
2514 * keep running sum of non-absolute differences & count of bytes)
2515 * [track dispersion, too? restart average if dispersion too large?]
2516 *
2517 * (1b) minimum sum of absolute differences from sliding average, probably
2518 * with window size <= deflate window (usually 32K)
2519 *
2520 * (2) minimum sum of squared differences from zero or running average
2521 * (i.e., ~ root-mean-square approach)
2522 */
2523
2524
2525 /* We don't need to test the 'no filter' case if this is the only filter
2526 * that has been chosen, as it doesn't actually do anything to the data.
2527 */
2528 best_row = png_ptr->row_buf;
2529
2530
2531 if ((filter_to_do & PNG_FILTER_NONE) != 0 && filter_to_do != PNG_FILTER_NONE)
2532 {
2533 png_bytep rp;
2534 png_size_t sum = 0;
2535 png_size_t i;
2536 int v;
2537
2538 if (PNG_SIZE_MAX/128 <= row_bytes)
2539 {
2540 for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
2541 {
2542 /* Check for overflow */
2543 if (sum > PNG_SIZE_MAX/128 - 256)
2544 break;
2545
2546 v = *rp;
2547 sum += (v < 128) ? v : 256 - v;
2548 }
2549 }
2550 else /* Overflow is not possible */
2551 {
2552 for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
2553 {
2554 v = *rp;
2555 sum += (v < 128) ? v : 256 - v;
2556 }
2557 }
2558
2559 mins = sum;
2560 }
2561
2562 /* Sub filter */
2563 if (filter_to_do == PNG_FILTER_SUB)
2564 /* It's the only filter so no testing is needed */
2565 {
2566 (void) png_setup_sub_row(png_ptr, bpp, row_bytes, mins);
2567 best_row = png_ptr->try_row;
2568 }
2569
2570 else if ((filter_to_do & PNG_FILTER_SUB) != 0)
2571 {
2572 png_size_t sum;
2573 png_size_t lmins = mins;
2574
2575 sum = png_setup_sub_row(png_ptr, bpp, row_bytes, lmins);
2576
2577 if (sum < mins)
2578 {
2579 mins = sum;
2580 best_row = png_ptr->try_row;
2581 if (png_ptr->tst_row != NULL)
2582 {
2583 png_ptr->try_row = png_ptr->tst_row;
2584 png_ptr->tst_row = best_row;
2585 }
2586 }
2587 }
2588
2589 /* Up filter */
2590 if (filter_to_do == PNG_FILTER_UP)
2591 {
2592 (void) png_setup_up_row(png_ptr, row_bytes, mins);
2593 best_row = png_ptr->try_row;
2594 }
2595
2596 else if ((filter_to_do & PNG_FILTER_UP) != 0)
2597 {
2598 png_size_t sum;
2599 png_size_t lmins = mins;
2600
2601 sum = png_setup_up_row(png_ptr, row_bytes, lmins);
2602
2603 if (sum < mins)
2604 {
2605 mins = sum;
2606 best_row = png_ptr->try_row;
2607 if (png_ptr->tst_row != NULL)
2608 {
2609 png_ptr->try_row = png_ptr->tst_row;
2610 png_ptr->tst_row = best_row;
2611 }
2612 }
2613 }
2614
2615 /* Avg filter */
2616 if (filter_to_do == PNG_FILTER_AVG)
2617 {
2618 (void) png_setup_avg_row(png_ptr, bpp, row_bytes, mins);
2619 best_row = png_ptr->try_row;
2620 }
2621
2622 else if ((filter_to_do & PNG_FILTER_AVG) != 0)
2623 {
2624 png_size_t sum;
2625 png_size_t lmins = mins;
2626
2627 sum= png_setup_avg_row(png_ptr, bpp, row_bytes, lmins);
2628
2629 if (sum < mins)
2630 {
2631 mins = sum;
2632 best_row = png_ptr->try_row;
2633 if (png_ptr->tst_row != NULL)
2634 {
2635 png_ptr->try_row = png_ptr->tst_row;
2636 png_ptr->tst_row = best_row;
2637 }
2638 }
2639 }
2640
2641 /* Paeth filter */
2642 if ((filter_to_do == PNG_FILTER_PAETH) != 0)
2643 {
2644 (void) png_setup_paeth_row(png_ptr, bpp, row_bytes, mins);
2645 best_row = png_ptr->try_row;
2646 }
2647
2648 else if ((filter_to_do & PNG_FILTER_PAETH) != 0)
2649 {
2650 png_size_t sum;
2651 png_size_t lmins = mins;
2652
2653 sum = png_setup_paeth_row(png_ptr, bpp, row_bytes, lmins);
2654
2655 if (sum < mins)
2656 {
2657 best_row = png_ptr->try_row;
2658 if (png_ptr->tst_row != NULL)
2659 {
2660 png_ptr->try_row = png_ptr->tst_row;
2661 png_ptr->tst_row = best_row;
2662 }
2663 }
2664 }
2665
2666 /* Do the actual writing of the filtered row data from the chosen filter. */
2667 png_write_filtered_row(png_ptr, best_row, row_info->rowbytes+1);
2668
2669 #endif /* WRITE_FILTER */
2670 }
2671
2672
2673 /* Do the actual writing of a previously filtered row. */
2674 static void
2675 png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row,
2676 png_size_t full_row_length/*includes filter byte*/)
2677 {
2678 png_debug(1, "in png_write_filtered_row");
2679
2680 png_debug1(2, "filter = %d", filtered_row[0]);
2681
2682 png_compress_IDAT(png_ptr, filtered_row, full_row_length, Z_NO_FLUSH);
2683
2684 #ifdef PNG_WRITE_FILTER_SUPPORTED
2685 /* Swap the current and previous rows */
2686 if (png_ptr->prev_row != NULL)
2687 {
2688 png_bytep tptr;
2689
2690 tptr = png_ptr->prev_row;
2691 png_ptr->prev_row = png_ptr->row_buf;
2692 png_ptr->row_buf = tptr;
2693 }
2694 #endif /* WRITE_FILTER */
2695
2696 /* Finish row - updates counters and flushes zlib if last row */
2697 png_write_finish_row(png_ptr);
2698
2699 #ifdef PNG_WRITE_FLUSH_SUPPORTED
2700 png_ptr->flush_rows++;
2701
2702 if (png_ptr->flush_dist > 0 &&
2703 png_ptr->flush_rows >= png_ptr->flush_dist)
2704 {
2705 png_write_flush(png_ptr);
2706 }
2707 #endif /* WRITE_FLUSH */
2708 }
2709 #endif /* WRITE */