2
/* pngwutil.c - utilities to write a PNG file
4
* Copyright (c) 2018-2024 Cosmin Truta
5
* Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
6
* Copyright (c) 1996-1997 Andreas Dilger
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* Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
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* This code is released under the libpng license.
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* For conditions of distribution and use, see the disclaimer
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* and license in png.h
16
#ifdef PNG_WRITE_SUPPORTED
18
#ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
19
/* Place a 32-bit number into a buffer in PNG byte order. We work
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* with unsigned numbers for convenience, although one supported
21
* ancillary chunk uses signed (two's complement) numbers.
24
png_save_uint_32(png_bytep buf, png_uint_32 i)
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buf[0] = (png_byte)((i >> 24) & 0xffU);
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buf[1] = (png_byte)((i >> 16) & 0xffU);
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buf[2] = (png_byte)((i >> 8) & 0xffU);
29
buf[3] = (png_byte)( i & 0xffU);
32
/* Place a 16-bit number into a buffer in PNG byte order.
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* The parameter is declared unsigned int, not png_uint_16,
34
* just to avoid potential problems on pre-ANSI C compilers.
37
png_save_uint_16(png_bytep buf, unsigned int i)
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buf[0] = (png_byte)((i >> 8) & 0xffU);
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buf[1] = (png_byte)( i & 0xffU);
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/* Simple function to write the signature. If we have already written
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* 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,
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* we should call png_set_sig_bytes() to tell libpng how many of the
48
* bytes have already been written.
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png_write_sig(png_structrp png_ptr)
53
png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};55
#ifdef PNG_IO_STATE_SUPPORTED
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/* Inform the I/O callback that the signature is being written */
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png_ptr->io_state = PNG_IO_WRITING | PNG_IO_SIGNATURE;
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/* Write the rest of the 8 byte signature */
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png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes],
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(size_t)(8 - png_ptr->sig_bytes));
64
if (png_ptr->sig_bytes < 3)
65
png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
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/* Write the start of a PNG chunk. The type is the chunk type.
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* The total_length is the sum of the lengths of all the data you will be
70
* passing in png_write_chunk_data().
73
png_write_chunk_header(png_structrp png_ptr, png_uint_32 chunk_name,
78
#if defined(PNG_DEBUG) && (PNG_DEBUG > 0)
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PNG_CSTRING_FROM_CHUNK(buf, chunk_name);
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png_debug2(0, "Writing %s chunk, length = %lu", buf, (unsigned long)length);
86
#ifdef PNG_IO_STATE_SUPPORTED
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/* Inform the I/O callback that the chunk header is being written.
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* PNG_IO_CHUNK_HDR requires a single I/O call.
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png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_HDR;
93
/* Write the length and the chunk name */
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png_save_uint_32(buf, length);
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png_save_uint_32(buf + 4, chunk_name);
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png_write_data(png_ptr, buf, 8);
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/* Put the chunk name into png_ptr->chunk_name */
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png_ptr->chunk_name = chunk_name;
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/* Reset the crc and run it over the chunk name */
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png_reset_crc(png_ptr);
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png_calculate_crc(png_ptr, buf + 4, 4);
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#ifdef PNG_IO_STATE_SUPPORTED
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/* Inform the I/O callback that chunk data will (possibly) be written.
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* PNG_IO_CHUNK_DATA does NOT require a specific number of I/O calls.
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png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_DATA;
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png_write_chunk_start(png_structrp png_ptr, png_const_bytep chunk_string,
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png_write_chunk_header(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), length);
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/* Write the data of a PNG chunk started with png_write_chunk_header().
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* 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().
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png_write_chunk_data(png_structrp png_ptr, png_const_bytep data, size_t length)
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/* Write the data, and run the CRC over it */
133
if (data != NULL && length > 0)
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png_write_data(png_ptr, data, length);
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/* Update the CRC after writing the data,
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* in case the user I/O routine alters it.
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png_calculate_crc(png_ptr, data, length);
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/* Finish a chunk started with png_write_chunk_header(). */
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png_write_chunk_end(png_structrp png_ptr)
150
if (png_ptr == NULL) return;
152
#ifdef PNG_IO_STATE_SUPPORTED
153
/* Inform the I/O callback that the chunk CRC is being written.
154
* PNG_IO_CHUNK_CRC requires a single I/O function call.
156
png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_CRC;
159
/* Write the crc in a single operation */
160
png_save_uint_32(buf, png_ptr->crc);
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png_write_data(png_ptr, buf, 4);
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/* Write a PNG chunk all at once. The type is an array of ASCII characters
166
* representing the chunk name. The array must be at least 4 bytes in
167
* length, and does not need to be null terminated. To be safe, pass the
168
* pre-defined chunk names here, and if you need a new one, define it
169
* where the others are defined. The length is the length of the data.
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* All the data must be present. If that is not possible, use the
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* png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end()
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png_write_complete_chunk(png_structrp png_ptr, png_uint_32 chunk_name,
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png_const_bytep data, size_t length)
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/* On 64-bit architectures 'length' may not fit in a png_uint_32. */
182
if (length > PNG_UINT_31_MAX)
183
png_error(png_ptr, "length exceeds PNG maximum");
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png_write_chunk_header(png_ptr, chunk_name, (png_uint_32)length);
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png_write_chunk_data(png_ptr, data, length);
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png_write_chunk_end(png_ptr);
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/* This is the API that calls the internal function above. */
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png_write_chunk(png_structrp png_ptr, png_const_bytep chunk_string,
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png_const_bytep data, size_t length)
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png_write_complete_chunk(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), data,
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/* This is used below to find the size of an image to pass to png_deflate_claim,
200
* so it only needs to be accurate if the size is less than 16384 bytes (the
201
* point at which a lower LZ window size can be used.)
203
static png_alloc_size_t
204
png_image_size(png_structrp png_ptr)
206
/* Only return sizes up to the maximum of a png_uint_32; do this by limiting
207
* the width and height used to 15 bits.
209
png_uint_32 h = png_ptr->height;
211
if (png_ptr->rowbytes < 32768 && h < 32768)
213
if (png_ptr->interlaced != 0)
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/* Interlacing makes the image larger because of the replication of
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* both the filter byte and the padding to a byte boundary.
218
png_uint_32 w = png_ptr->width;
219
unsigned int pd = png_ptr->pixel_depth;
220
png_alloc_size_t cb_base;
223
for (cb_base=0, pass=0; pass<=6; ++pass)
225
png_uint_32 pw = PNG_PASS_COLS(w, pass);
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cb_base += (PNG_ROWBYTES(pd, pw)+1) * PNG_PASS_ROWS(h, pass);
235
return (png_ptr->rowbytes+1) * h;
242
#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
243
/* This is the code to hack the first two bytes of the deflate stream (the
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* deflate header) to correct the windowBits value to match the actual data
245
* size. Note that the second argument is the *uncompressed* size but the
246
* first argument is the *compressed* data (and it must be deflate
250
optimize_cmf(png_bytep data, png_alloc_size_t data_size)
252
/* Optimize the CMF field in the zlib stream. The resultant zlib stream is
253
* still compliant to the stream specification.
255
if (data_size <= 16384) /* else windowBits must be 15 */
257
unsigned int z_cmf = data[0]; /* zlib compression method and flags */
259
if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
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unsigned int z_cinfo;
262
unsigned int half_z_window_size;
264
z_cinfo = z_cmf >> 4;
265
half_z_window_size = 1U << (z_cinfo + 7);
267
if (data_size <= half_z_window_size) /* else no change */
273
half_z_window_size >>= 1;
276
while (z_cinfo > 0 && data_size <= half_z_window_size);
278
z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
280
data[0] = (png_byte)z_cmf;
281
tmp = data[1] & 0xe0;
282
tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
283
data[1] = (png_byte)tmp;
288
#endif /* WRITE_OPTIMIZE_CMF */
290
/* Initialize the compressor for the appropriate type of compression. */
292
png_deflate_claim(png_structrp png_ptr, png_uint_32 owner,
293
png_alloc_size_t data_size)
295
if (png_ptr->zowner != 0)
297
#if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_ERROR_TEXT_SUPPORTED)
300
PNG_STRING_FROM_CHUNK(msg, owner);
303
PNG_STRING_FROM_CHUNK(msg+6, png_ptr->zowner);
304
/* So the message that results is "<chunk> using zstream"; this is an
305
* internal error, but is very useful for debugging. i18n requirements
308
(void)png_safecat(msg, (sizeof msg), 10, " using zstream");
311
png_warning(png_ptr, msg);
313
/* Attempt sane error recovery */
314
if (png_ptr->zowner == png_IDAT) /* don't steal from IDAT */
316
png_ptr->zstream.msg = PNGZ_MSG_CAST("in use by IDAT");317
return Z_STREAM_ERROR;
322
png_error(png_ptr, msg);
327
int level = png_ptr->zlib_level;
328
int method = png_ptr->zlib_method;
329
int windowBits = png_ptr->zlib_window_bits;
330
int memLevel = png_ptr->zlib_mem_level;
331
int strategy; /* set below */
332
int ret; /* zlib return code */
334
if (owner == png_IDAT)
336
if ((png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY) != 0)
337
strategy = png_ptr->zlib_strategy;
339
else if (png_ptr->do_filter != PNG_FILTER_NONE)
340
strategy = PNG_Z_DEFAULT_STRATEGY;
343
strategy = PNG_Z_DEFAULT_NOFILTER_STRATEGY;
348
#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
349
level = png_ptr->zlib_text_level;
350
method = png_ptr->zlib_text_method;
351
windowBits = png_ptr->zlib_text_window_bits;
352
memLevel = png_ptr->zlib_text_mem_level;
353
strategy = png_ptr->zlib_text_strategy;
355
/* If customization is not supported the values all come from the
356
* IDAT values except for the strategy, which is fixed to the
357
* default. (This is the pre-1.6.0 behavior too, although it was
358
* implemented in a very different way.)
360
strategy = Z_DEFAULT_STRATEGY;
364
/* Adjust 'windowBits' down if larger than 'data_size'; to stop this
365
* happening just pass 32768 as the data_size parameter. Notice that zlib
366
* requires an extra 262 bytes in the window in addition to the data to be
367
* able to see the whole of the data, so if data_size+262 takes us to the
368
* next windowBits size we need to fix up the value later. (Because even
369
* though deflate needs the extra window, inflate does not!)
371
if (data_size <= 16384)
373
/* IMPLEMENTATION NOTE: this 'half_window_size' stuff is only here to
374
* work round a Microsoft Visual C misbehavior which, contrary to C-90,
375
* widens the result of the following shift to 64-bits if (and,
376
* apparently, only if) it is used in a test.
378
unsigned int half_window_size = 1U << (windowBits-1);
380
while (data_size + 262 <= half_window_size)
382
half_window_size >>= 1;
387
/* Check against the previous initialized values, if any. */
388
if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0 &&
389
(png_ptr->zlib_set_level != level ||
390
png_ptr->zlib_set_method != method ||
391
png_ptr->zlib_set_window_bits != windowBits ||
392
png_ptr->zlib_set_mem_level != memLevel ||
393
png_ptr->zlib_set_strategy != strategy))
395
if (deflateEnd(&png_ptr->zstream) != Z_OK)
396
png_warning(png_ptr, "deflateEnd failed (ignored)");
398
png_ptr->flags &= ~PNG_FLAG_ZSTREAM_INITIALIZED;
401
/* For safety clear out the input and output pointers (currently zlib
402
* doesn't use them on Init, but it might in the future).
404
png_ptr->zstream.next_in = NULL;
405
png_ptr->zstream.avail_in = 0;
406
png_ptr->zstream.next_out = NULL;
407
png_ptr->zstream.avail_out = 0;
409
/* Now initialize if required, setting the new parameters, otherwise just
410
* do a simple reset to the previous parameters.
412
if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
413
ret = deflateReset(&png_ptr->zstream);
417
ret = deflateInit2(&png_ptr->zstream, level, method, windowBits,
421
png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
424
/* The return code is from either deflateReset or deflateInit2; they have
425
* pretty much the same set of error codes.
428
png_ptr->zowner = owner;
431
png_zstream_error(png_ptr, ret);
437
/* Clean up (or trim) a linked list of compression buffers. */
439
png_free_buffer_list(png_structrp png_ptr, png_compression_bufferp *listp)
441
png_compression_bufferp list = *listp;
449
png_compression_bufferp next = list->next;
451
png_free(png_ptr, list);
454
while (list != NULL);
458
#ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
459
/* This pair of functions encapsulates the operation of (a) compressing a
460
* text string, and (b) issuing it later as a series of chunk data writes.
461
* The compression_state structure is shared context for these functions
462
* set up by the caller to allow access to the relevant local variables.
464
* compression_buffer (new in 1.6.0) is just a linked list of zbuffer_size
465
* temporary buffers. From 1.6.0 it is retained in png_struct so that it will
466
* be correctly freed in the event of a write error (previous implementations
467
* just leaked memory.)
471
png_const_bytep input; /* The uncompressed input data */
472
png_alloc_size_t input_len; /* Its length */
473
png_uint_32 output_len; /* Final compressed length */
474
png_byte output[1024]; /* First block of output */
478
png_text_compress_init(compression_state *comp, png_const_bytep input,
479
png_alloc_size_t input_len)
482
comp->input_len = input_len;
483
comp->output_len = 0;
486
/* Compress the data in the compression state input */
488
png_text_compress(png_structrp png_ptr, png_uint_32 chunk_name,
489
compression_state *comp, png_uint_32 prefix_len)
493
/* To find the length of the output it is necessary to first compress the
494
* input. The result is buffered rather than using the two-pass algorithm
495
* that is used on the inflate side; deflate is assumed to be slower and a
496
* PNG writer is assumed to have more memory available than a PNG reader.
498
* IMPLEMENTATION NOTE: the zlib API deflateBound() can be used to find an
499
* upper limit on the output size, but it is always bigger than the input
500
* size so it is likely to be more efficient to use this linked-list
503
ret = png_deflate_claim(png_ptr, chunk_name, comp->input_len);
508
/* Set up the compression buffers, we need a loop here to avoid overflowing a
509
* uInt. Use ZLIB_IO_MAX to limit the input. The output is always limited
510
* by the output buffer size, so there is no need to check that. Since this
511
* is ANSI-C we know that an 'int', hence a uInt, is always at least 16 bits
515
png_compression_bufferp *end = &png_ptr->zbuffer_list;
516
png_alloc_size_t input_len = comp->input_len; /* may be zero! */
517
png_uint_32 output_len;
519
/* zlib updates these for us: */
520
png_ptr->zstream.next_in = PNGZ_INPUT_CAST(comp->input);
521
png_ptr->zstream.avail_in = 0; /* Set below */
522
png_ptr->zstream.next_out = comp->output;
523
png_ptr->zstream.avail_out = (sizeof comp->output);
525
output_len = png_ptr->zstream.avail_out;
529
uInt avail_in = ZLIB_IO_MAX;
531
if (avail_in > input_len)
532
avail_in = (uInt)input_len;
534
input_len -= avail_in;
536
png_ptr->zstream.avail_in = avail_in;
538
if (png_ptr->zstream.avail_out == 0)
540
png_compression_buffer *next;
542
/* Chunk data is limited to 2^31 bytes in length, so the prefix
543
* length must be counted here.
545
if (output_len + prefix_len > PNG_UINT_31_MAX)
551
/* Need a new (malloc'ed) buffer, but there may be one present
557
next = png_voidcast(png_compression_bufferp, png_malloc_base
558
(png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr)));
566
/* Link in this buffer (so that it will be freed later) */
571
png_ptr->zstream.next_out = next->output;
572
png_ptr->zstream.avail_out = png_ptr->zbuffer_size;
573
output_len += png_ptr->zstream.avail_out;
575
/* Move 'end' to the next buffer pointer. */
579
/* Compress the data */
580
ret = deflate(&png_ptr->zstream,
581
input_len > 0 ? Z_NO_FLUSH : Z_FINISH);
583
/* Claw back input data that was not consumed (because avail_in is
584
* reset above every time round the loop).
586
input_len += png_ptr->zstream.avail_in;
587
png_ptr->zstream.avail_in = 0; /* safety */
591
/* There may be some space left in the last output buffer. This needs to
592
* be subtracted from output_len.
594
output_len -= png_ptr->zstream.avail_out;
595
png_ptr->zstream.avail_out = 0; /* safety */
596
comp->output_len = output_len;
598
/* Now double check the output length, put in a custom message if it is
599
* too long. Otherwise ensure the z_stream::msg pointer is set to
602
if (output_len + prefix_len >= PNG_UINT_31_MAX)
604
png_ptr->zstream.msg = PNGZ_MSG_CAST("compressed data too long");609
png_zstream_error(png_ptr, ret);
611
/* Reset zlib for another zTXt/iTXt or image data */
614
/* The only success case is Z_STREAM_END, input_len must be 0; if not this
615
* is an internal error.
617
if (ret == Z_STREAM_END && input_len == 0)
619
#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
620
/* Fix up the deflate header, if required */
621
optimize_cmf(comp->output, comp->input_len);
623
/* But Z_OK is returned, not Z_STREAM_END; this allows the claim
624
* function above to return Z_STREAM_END on an error (though it never
625
* does in the current versions of zlib.)
635
/* Ship the compressed text out via chunk writes */
637
png_write_compressed_data_out(png_structrp png_ptr, compression_state *comp)
639
png_uint_32 output_len = comp->output_len;
640
png_const_bytep output = comp->output;
641
png_uint_32 avail = (sizeof comp->output);
642
png_compression_buffer *next = png_ptr->zbuffer_list;
646
if (avail > output_len)
649
png_write_chunk_data(png_ptr, output, avail);
653
if (output_len == 0 || next == NULL)
656
avail = png_ptr->zbuffer_size;
657
output = next->output;
661
/* This is an internal error; 'next' must have been NULL! */
663
png_error(png_ptr, "error writing ancillary chunked compressed data");
665
#endif /* WRITE_COMPRESSED_TEXT */
667
/* Write the IHDR chunk, and update the png_struct with the necessary
668
* information. Note that the rest of this code depends upon this
669
* information being correct.
672
png_write_IHDR(png_structrp png_ptr, png_uint_32 width, png_uint_32 height,
673
int bit_depth, int color_type, int compression_type, int filter_type,
676
png_byte buf[13]; /* Buffer to store the IHDR info */
677
int is_invalid_depth;
679
png_debug(1, "in png_write_IHDR");
681
/* Check that we have valid input data from the application info */
684
case PNG_COLOR_TYPE_GRAY:
691
#ifdef PNG_WRITE_16BIT_SUPPORTED
694
png_ptr->channels = 1; break;
698
"Invalid bit depth for grayscale image");
702
case PNG_COLOR_TYPE_RGB:
703
is_invalid_depth = (bit_depth != 8);
704
#ifdef PNG_WRITE_16BIT_SUPPORTED
705
is_invalid_depth = (is_invalid_depth && bit_depth != 16);
707
if (is_invalid_depth)
708
png_error(png_ptr, "Invalid bit depth for RGB image");
710
png_ptr->channels = 3;
713
case PNG_COLOR_TYPE_PALETTE:
720
png_ptr->channels = 1;
724
png_error(png_ptr, "Invalid bit depth for paletted image");
728
case PNG_COLOR_TYPE_GRAY_ALPHA:
729
is_invalid_depth = (bit_depth != 8);
730
#ifdef PNG_WRITE_16BIT_SUPPORTED
731
is_invalid_depth = (is_invalid_depth && bit_depth != 16);
733
if (is_invalid_depth)
734
png_error(png_ptr, "Invalid bit depth for grayscale+alpha image");
736
png_ptr->channels = 2;
739
case PNG_COLOR_TYPE_RGB_ALPHA:
740
is_invalid_depth = (bit_depth != 8);
741
#ifdef PNG_WRITE_16BIT_SUPPORTED
742
is_invalid_depth = (is_invalid_depth && bit_depth != 16);
744
if (is_invalid_depth)
745
png_error(png_ptr, "Invalid bit depth for RGBA image");
747
png_ptr->channels = 4;
751
png_error(png_ptr, "Invalid image color type specified");
754
if (compression_type != PNG_COMPRESSION_TYPE_BASE)
756
png_warning(png_ptr, "Invalid compression type specified");
757
compression_type = PNG_COMPRESSION_TYPE_BASE;
760
/* Write filter_method 64 (intrapixel differencing) only if
761
* 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
762
* 2. Libpng did not write a PNG signature (this filter_method is only
763
* used in PNG datastreams that are embedded in MNG datastreams) and
764
* 3. The application called png_permit_mng_features with a mask that
765
* included PNG_FLAG_MNG_FILTER_64 and
766
* 4. The filter_method is 64 and
767
* 5. The color_type is RGB or RGBA
770
#ifdef PNG_MNG_FEATURES_SUPPORTED
771
!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
772
((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
773
(color_type == PNG_COLOR_TYPE_RGB ||
774
color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&
775
(filter_type == PNG_INTRAPIXEL_DIFFERENCING)) &&
777
filter_type != PNG_FILTER_TYPE_BASE)
779
png_warning(png_ptr, "Invalid filter type specified");
780
filter_type = PNG_FILTER_TYPE_BASE;
783
#ifdef PNG_WRITE_INTERLACING_SUPPORTED
784
if (interlace_type != PNG_INTERLACE_NONE &&
785
interlace_type != PNG_INTERLACE_ADAM7)
787
png_warning(png_ptr, "Invalid interlace type specified");
788
interlace_type = PNG_INTERLACE_ADAM7;
791
interlace_type=PNG_INTERLACE_NONE;
794
/* Save the relevant information */
795
png_ptr->bit_depth = (png_byte)bit_depth;
796
png_ptr->color_type = (png_byte)color_type;
797
png_ptr->interlaced = (png_byte)interlace_type;
798
#ifdef PNG_MNG_FEATURES_SUPPORTED
799
png_ptr->filter_type = (png_byte)filter_type;
801
png_ptr->compression_type = (png_byte)compression_type;
802
png_ptr->width = width;
803
png_ptr->height = height;
805
png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels);
806
png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width);
807
/* Set the usr info, so any transformations can modify it */
808
png_ptr->usr_width = png_ptr->width;
809
png_ptr->usr_bit_depth = png_ptr->bit_depth;
810
png_ptr->usr_channels = png_ptr->channels;
812
/* Pack the header information into the buffer */
813
png_save_uint_32(buf, width);
814
png_save_uint_32(buf + 4, height);
815
buf[8] = (png_byte)bit_depth;
816
buf[9] = (png_byte)color_type;
817
buf[10] = (png_byte)compression_type;
818
buf[11] = (png_byte)filter_type;
819
buf[12] = (png_byte)interlace_type;
821
/* Write the chunk */
822
png_write_complete_chunk(png_ptr, png_IHDR, buf, 13);
824
if ((png_ptr->do_filter) == PNG_NO_FILTERS)
826
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
827
png_ptr->bit_depth < 8)
828
png_ptr->do_filter = PNG_FILTER_NONE;
831
png_ptr->do_filter = PNG_ALL_FILTERS;
834
png_ptr->mode = PNG_HAVE_IHDR; /* not READY_FOR_ZTXT */
837
/* Write the palette. We are careful not to trust png_color to be in the
838
* correct order for PNG, so people can redefine it to any convenient
842
png_write_PLTE(png_structrp png_ptr, png_const_colorp palette,
845
png_uint_32 max_palette_length, i;
846
png_const_colorp pal_ptr;
849
png_debug(1, "in png_write_PLTE");
851
max_palette_length = (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ?
852
(1 << png_ptr->bit_depth) : PNG_MAX_PALETTE_LENGTH;
855
#ifdef PNG_MNG_FEATURES_SUPPORTED
856
(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0 &&
858
num_pal == 0) || num_pal > max_palette_length)
860
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
862
png_error(png_ptr, "Invalid number of colors in palette");
867
png_warning(png_ptr, "Invalid number of colors in palette");
872
if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
875
"Ignoring request to write a PLTE chunk in grayscale PNG");
880
png_ptr->num_palette = (png_uint_16)num_pal;
881
png_debug1(3, "num_palette = %d", png_ptr->num_palette);
883
png_write_chunk_header(png_ptr, png_PLTE, (png_uint_32)(num_pal * 3));
884
#ifdef PNG_POINTER_INDEXING_SUPPORTED
886
for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++)
888
buf[0] = pal_ptr->red;
889
buf[1] = pal_ptr->green;
890
buf[2] = pal_ptr->blue;
891
png_write_chunk_data(png_ptr, buf, 3);
895
/* This is a little slower but some buggy compilers need to do this
900
for (i = 0; i < num_pal; i++)
902
buf[0] = pal_ptr[i].red;
903
buf[1] = pal_ptr[i].green;
904
buf[2] = pal_ptr[i].blue;
905
png_write_chunk_data(png_ptr, buf, 3);
909
png_write_chunk_end(png_ptr);
910
png_ptr->mode |= PNG_HAVE_PLTE;
913
/* This is similar to png_text_compress, above, except that it does not require
914
* all of the data at once and, instead of buffering the compressed result,
915
* writes it as IDAT chunks. Unlike png_text_compress it *can* png_error out
916
* because it calls the write interface. As a result it does its own error
917
* reporting and does not return an error code. In the event of error it will
918
* just call png_error. The input data length may exceed 32-bits. The 'flush'
919
* parameter is exactly the same as that to deflate, with the following
922
* Z_NO_FLUSH: normal incremental output of compressed data
923
* Z_SYNC_FLUSH: do a SYNC_FLUSH, used by png_write_flush
924
* Z_FINISH: this is the end of the input, do a Z_FINISH and clean up
926
* The routine manages the acquire and release of the png_ptr->zstream by
927
* checking and (at the end) clearing png_ptr->zowner; it does some sanity
928
* checks on the 'mode' flags while doing this.
931
png_compress_IDAT(png_structrp png_ptr, png_const_bytep input,
932
png_alloc_size_t input_len, int flush)
934
if (png_ptr->zowner != png_IDAT)
936
/* First time. Ensure we have a temporary buffer for compression and
937
* trim the buffer list if it has more than one entry to free memory.
938
* If 'WRITE_COMPRESSED_TEXT' is not set the list will never have been
939
* created at this point, but the check here is quick and safe.
941
if (png_ptr->zbuffer_list == NULL)
943
png_ptr->zbuffer_list = png_voidcast(png_compression_bufferp,
944
png_malloc(png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr)));
945
png_ptr->zbuffer_list->next = NULL;
949
png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list->next);
951
/* It is a terminal error if we can't claim the zstream. */
952
if (png_deflate_claim(png_ptr, png_IDAT, png_image_size(png_ptr)) != Z_OK)
953
png_error(png_ptr, png_ptr->zstream.msg);
955
/* The output state is maintained in png_ptr->zstream, so it must be
956
* initialized here after the claim.
958
png_ptr->zstream.next_out = png_ptr->zbuffer_list->output;
959
png_ptr->zstream.avail_out = png_ptr->zbuffer_size;
962
/* Now loop reading and writing until all the input is consumed or an error
963
* terminates the operation. The _out values are maintained across calls to
964
* this function, but the input must be reset each time.
966
png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
967
png_ptr->zstream.avail_in = 0; /* set below */
972
/* INPUT: from the row data */
973
uInt avail = ZLIB_IO_MAX;
975
if (avail > input_len)
976
avail = (uInt)input_len; /* safe because of the check */
978
png_ptr->zstream.avail_in = avail;
981
ret = deflate(&png_ptr->zstream, input_len > 0 ? Z_NO_FLUSH : flush);
983
/* Include as-yet unconsumed input */
984
input_len += png_ptr->zstream.avail_in;
985
png_ptr->zstream.avail_in = 0;
987
/* OUTPUT: write complete IDAT chunks when avail_out drops to zero. Note
988
* that these two zstream fields are preserved across the calls, therefore
989
* there is no need to set these up on entry to the loop.
991
if (png_ptr->zstream.avail_out == 0)
993
png_bytep data = png_ptr->zbuffer_list->output;
994
uInt size = png_ptr->zbuffer_size;
996
/* Write an IDAT containing the data then reset the buffer. The
997
* first IDAT may need deflate header optimization.
999
#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
1000
if ((png_ptr->mode & PNG_HAVE_IDAT) == 0 &&
1001
png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
1002
optimize_cmf(data, png_image_size(png_ptr));
1006
png_write_complete_chunk(png_ptr, png_IDAT, data, size);
1007
png_ptr->mode |= PNG_HAVE_IDAT;
1009
png_ptr->zstream.next_out = data;
1010
png_ptr->zstream.avail_out = size;
1012
/* For SYNC_FLUSH or FINISH it is essential to keep calling zlib with
1013
* the same flush parameter until it has finished output, for NO_FLUSH
1014
* it doesn't matter.
1016
if (ret == Z_OK && flush != Z_NO_FLUSH)
1020
/* The order of these checks doesn't matter much; it just affects which
1021
* possible error might be detected if multiple things go wrong at once.
1023
if (ret == Z_OK) /* most likely return code! */
1025
/* If all the input has been consumed then just return. If Z_FINISH
1026
* was used as the flush parameter something has gone wrong if we get
1031
if (flush == Z_FINISH)
1032
png_error(png_ptr, "Z_OK on Z_FINISH with output space");
1038
else if (ret == Z_STREAM_END && flush == Z_FINISH)
1040
/* This is the end of the IDAT data; any pending output must be
1041
* flushed. For small PNG files we may still be at the beginning.
1043
png_bytep data = png_ptr->zbuffer_list->output;
1044
uInt size = png_ptr->zbuffer_size - png_ptr->zstream.avail_out;
1046
#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
1047
if ((png_ptr->mode & PNG_HAVE_IDAT) == 0 &&
1048
png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
1049
optimize_cmf(data, png_image_size(png_ptr));
1053
png_write_complete_chunk(png_ptr, png_IDAT, data, size);
1054
png_ptr->zstream.avail_out = 0;
1055
png_ptr->zstream.next_out = NULL;
1056
png_ptr->mode |= PNG_HAVE_IDAT | PNG_AFTER_IDAT;
1058
png_ptr->zowner = 0; /* Release the stream */
1064
/* This is an error condition. */
1065
png_zstream_error(png_ptr, ret);
1066
png_error(png_ptr, png_ptr->zstream.msg);
1071
/* Write an IEND chunk */
1073
png_write_IEND(png_structrp png_ptr)
1075
png_debug(1, "in png_write_IEND");
1077
png_write_complete_chunk(png_ptr, png_IEND, NULL, 0);
1078
png_ptr->mode |= PNG_HAVE_IEND;
1081
#ifdef PNG_WRITE_gAMA_SUPPORTED
1082
/* Write a gAMA chunk */
1084
png_write_gAMA_fixed(png_structrp png_ptr, png_fixed_point file_gamma)
1088
png_debug(1, "in png_write_gAMA");
1090
/* file_gamma is saved in 1/100,000ths */
1091
png_save_uint_32(buf, (png_uint_32)file_gamma);
1092
png_write_complete_chunk(png_ptr, png_gAMA, buf, 4);
1096
#ifdef PNG_WRITE_sRGB_SUPPORTED
1097
/* Write a sRGB chunk */
1099
png_write_sRGB(png_structrp png_ptr, int srgb_intent)
1103
png_debug(1, "in png_write_sRGB");
1105
if (srgb_intent >= PNG_sRGB_INTENT_LAST)
1106
png_warning(png_ptr,
1107
"Invalid sRGB rendering intent specified");
1109
buf[0]=(png_byte)srgb_intent;
1110
png_write_complete_chunk(png_ptr, png_sRGB, buf, 1);
1114
#ifdef PNG_WRITE_iCCP_SUPPORTED
1115
/* Write an iCCP chunk */
1117
png_write_iCCP(png_structrp png_ptr, png_const_charp name,
1118
png_const_bytep profile)
1120
png_uint_32 name_len;
1121
png_uint_32 profile_len;
1122
png_byte new_name[81]; /* 1 byte for the compression byte */
1123
compression_state comp;
1126
png_debug(1, "in png_write_iCCP");
1128
/* These are all internal problems: the profile should have been checked
1129
* before when it was stored.
1131
if (profile == NULL)
1132
png_error(png_ptr, "No profile for iCCP chunk"); /* internal error */
1134
profile_len = png_get_uint_32(profile);
1136
if (profile_len < 132)
1137
png_error(png_ptr, "ICC profile too short");
1139
temp = (png_uint_32) (*(profile+8));
1140
if (temp > 3 && (profile_len & 0x03))
1141
png_error(png_ptr, "ICC profile length invalid (not a multiple of 4)");
1144
png_uint_32 embedded_profile_len = png_get_uint_32(profile);
1146
if (profile_len != embedded_profile_len)
1147
png_error(png_ptr, "Profile length does not match profile");
1150
name_len = png_check_keyword(png_ptr, name, new_name);
1153
png_error(png_ptr, "iCCP: invalid keyword");
1155
new_name[++name_len] = PNG_COMPRESSION_TYPE_BASE;
1157
/* Make sure we include the NULL after the name and the compression type */
1160
png_text_compress_init(&comp, profile, profile_len);
1162
/* Allow for keyword terminator and compression byte */
1163
if (png_text_compress(png_ptr, png_iCCP, &comp, name_len) != Z_OK)
1164
png_error(png_ptr, png_ptr->zstream.msg);
1166
png_write_chunk_header(png_ptr, png_iCCP, name_len + comp.output_len);
1168
png_write_chunk_data(png_ptr, new_name, name_len);
1170
png_write_compressed_data_out(png_ptr, &comp);
1172
png_write_chunk_end(png_ptr);
1176
#ifdef PNG_WRITE_sPLT_SUPPORTED
1177
/* Write a sPLT chunk */
1179
png_write_sPLT(png_structrp png_ptr, png_const_sPLT_tp spalette)
1181
png_uint_32 name_len;
1182
png_byte new_name[80];
1183
png_byte entrybuf[10];
1184
size_t entry_size = (spalette->depth == 8 ? 6 : 10);
1185
size_t palette_size = entry_size * (size_t)spalette->nentries;
1187
#ifndef PNG_POINTER_INDEXING_SUPPORTED
1191
png_debug(1, "in png_write_sPLT");
1193
name_len = png_check_keyword(png_ptr, spalette->name, new_name);
1196
png_error(png_ptr, "sPLT: invalid keyword");
1198
/* Make sure we include the NULL after the name */
1199
png_write_chunk_header(png_ptr, png_sPLT,
1200
(png_uint_32)(name_len + 2 + palette_size));
1202
png_write_chunk_data(png_ptr, (png_bytep)new_name, (size_t)(name_len + 1));
1204
png_write_chunk_data(png_ptr, &spalette->depth, 1);
1206
/* Loop through each palette entry, writing appropriately */
1207
#ifdef PNG_POINTER_INDEXING_SUPPORTED
1208
for (ep = spalette->entries; ep<spalette->entries + spalette->nentries; ep++)
1210
if (spalette->depth == 8)
1212
entrybuf[0] = (png_byte)ep->red;
1213
entrybuf[1] = (png_byte)ep->green;
1214
entrybuf[2] = (png_byte)ep->blue;
1215
entrybuf[3] = (png_byte)ep->alpha;
1216
png_save_uint_16(entrybuf + 4, ep->frequency);
1221
png_save_uint_16(entrybuf + 0, ep->red);
1222
png_save_uint_16(entrybuf + 2, ep->green);
1223
png_save_uint_16(entrybuf + 4, ep->blue);
1224
png_save_uint_16(entrybuf + 6, ep->alpha);
1225
png_save_uint_16(entrybuf + 8, ep->frequency);
1228
png_write_chunk_data(png_ptr, entrybuf, entry_size);
1231
ep=spalette->entries;
1232
for (i = 0; i>spalette->nentries; i++)
1234
if (spalette->depth == 8)
1236
entrybuf[0] = (png_byte)ep[i].red;
1237
entrybuf[1] = (png_byte)ep[i].green;
1238
entrybuf[2] = (png_byte)ep[i].blue;
1239
entrybuf[3] = (png_byte)ep[i].alpha;
1240
png_save_uint_16(entrybuf + 4, ep[i].frequency);
1245
png_save_uint_16(entrybuf + 0, ep[i].red);
1246
png_save_uint_16(entrybuf + 2, ep[i].green);
1247
png_save_uint_16(entrybuf + 4, ep[i].blue);
1248
png_save_uint_16(entrybuf + 6, ep[i].alpha);
1249
png_save_uint_16(entrybuf + 8, ep[i].frequency);
1252
png_write_chunk_data(png_ptr, entrybuf, entry_size);
1256
png_write_chunk_end(png_ptr);
1260
#ifdef PNG_WRITE_sBIT_SUPPORTED
1261
/* Write the sBIT chunk */
1263
png_write_sBIT(png_structrp png_ptr, png_const_color_8p sbit, int color_type)
1268
png_debug(1, "in png_write_sBIT");
1270
/* Make sure we don't depend upon the order of PNG_COLOR_8 */
1271
if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
1275
maxbits = (png_byte)(color_type==PNG_COLOR_TYPE_PALETTE ? 8 :
1276
png_ptr->usr_bit_depth);
1278
if (sbit->red == 0 || sbit->red > maxbits ||
1279
sbit->green == 0 || sbit->green > maxbits ||
1280
sbit->blue == 0 || sbit->blue > maxbits)
1282
png_warning(png_ptr, "Invalid sBIT depth specified");
1287
buf[1] = sbit->green;
1288
buf[2] = sbit->blue;
1294
if (sbit->gray == 0 || sbit->gray > png_ptr->usr_bit_depth)
1296
png_warning(png_ptr, "Invalid sBIT depth specified");
1300
buf[0] = sbit->gray;
1304
if ((color_type & PNG_COLOR_MASK_ALPHA) != 0)
1306
if (sbit->alpha == 0 || sbit->alpha > png_ptr->usr_bit_depth)
1308
png_warning(png_ptr, "Invalid sBIT depth specified");
1312
buf[size++] = sbit->alpha;
1315
png_write_complete_chunk(png_ptr, png_sBIT, buf, size);
1319
#ifdef PNG_WRITE_cHRM_SUPPORTED
1320
/* Write the cHRM chunk */
1322
png_write_cHRM_fixed(png_structrp png_ptr, const png_xy *xy)
1326
png_debug(1, "in png_write_cHRM");
1328
/* Each value is saved in 1/100,000ths */
1329
png_save_int_32(buf, xy->whitex);
1330
png_save_int_32(buf + 4, xy->whitey);
1332
png_save_int_32(buf + 8, xy->redx);
1333
png_save_int_32(buf + 12, xy->redy);
1335
png_save_int_32(buf + 16, xy->greenx);
1336
png_save_int_32(buf + 20, xy->greeny);
1338
png_save_int_32(buf + 24, xy->bluex);
1339
png_save_int_32(buf + 28, xy->bluey);
1341
png_write_complete_chunk(png_ptr, png_cHRM, buf, 32);
1345
#ifdef PNG_WRITE_tRNS_SUPPORTED
1346
/* Write the tRNS chunk */
1348
png_write_tRNS(png_structrp png_ptr, png_const_bytep trans_alpha,
1349
png_const_color_16p tran, int num_trans, int color_type)
1353
png_debug(1, "in png_write_tRNS");
1355
if (color_type == PNG_COLOR_TYPE_PALETTE)
1357
if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette)
1359
png_app_warning(png_ptr,
1360
"Invalid number of transparent colors specified");
1364
/* Write the chunk out as it is */
1365
png_write_complete_chunk(png_ptr, png_tRNS, trans_alpha,
1369
else if (color_type == PNG_COLOR_TYPE_GRAY)
1371
/* One 16-bit value */
1372
if (tran->gray >= (1 << png_ptr->bit_depth))
1374
png_app_warning(png_ptr,
1375
"Ignoring attempt to write tRNS chunk out-of-range for bit_depth");
1380
png_save_uint_16(buf, tran->gray);
1381
png_write_complete_chunk(png_ptr, png_tRNS, buf, 2);
1384
else if (color_type == PNG_COLOR_TYPE_RGB)
1386
/* Three 16-bit values */
1387
png_save_uint_16(buf, tran->red);
1388
png_save_uint_16(buf + 2, tran->green);
1389
png_save_uint_16(buf + 4, tran->blue);
1390
#ifdef PNG_WRITE_16BIT_SUPPORTED
1391
if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]) != 0)
1393
if ((buf[0] | buf[2] | buf[4]) != 0)
1396
png_app_warning(png_ptr,
1397
"Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8");
1401
png_write_complete_chunk(png_ptr, png_tRNS, buf, 6);
1406
png_app_warning(png_ptr, "Can't write tRNS with an alpha channel");
1411
#ifdef PNG_WRITE_bKGD_SUPPORTED
1412
/* Write the background chunk */
1414
png_write_bKGD(png_structrp png_ptr, png_const_color_16p back, int color_type)
1418
png_debug(1, "in png_write_bKGD");
1420
if (color_type == PNG_COLOR_TYPE_PALETTE)
1423
#ifdef PNG_MNG_FEATURES_SUPPORTED
1424
(png_ptr->num_palette != 0 ||
1425
(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0) &&
1427
back->index >= png_ptr->num_palette)
1429
png_warning(png_ptr, "Invalid background palette index");
1433
buf[0] = back->index;
1434
png_write_complete_chunk(png_ptr, png_bKGD, buf, 1);
1437
else if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
1439
png_save_uint_16(buf, back->red);
1440
png_save_uint_16(buf + 2, back->green);
1441
png_save_uint_16(buf + 4, back->blue);
1442
#ifdef PNG_WRITE_16BIT_SUPPORTED
1443
if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]) != 0)
1445
if ((buf[0] | buf[2] | buf[4]) != 0)
1448
png_warning(png_ptr,
1449
"Ignoring attempt to write 16-bit bKGD chunk "
1450
"when bit_depth is 8");
1455
png_write_complete_chunk(png_ptr, png_bKGD, buf, 6);
1460
if (back->gray >= (1 << png_ptr->bit_depth))
1462
png_warning(png_ptr,
1463
"Ignoring attempt to write bKGD chunk out-of-range for bit_depth");
1468
png_save_uint_16(buf, back->gray);
1469
png_write_complete_chunk(png_ptr, png_bKGD, buf, 2);
1474
#ifdef PNG_WRITE_eXIf_SUPPORTED
1475
/* Write the Exif data */
1477
png_write_eXIf(png_structrp png_ptr, png_bytep exif, int num_exif)
1482
png_debug(1, "in png_write_eXIf");
1484
png_write_chunk_header(png_ptr, png_eXIf, (png_uint_32)(num_exif));
1486
for (i = 0; i < num_exif; i++)
1489
png_write_chunk_data(png_ptr, buf, 1);
1492
png_write_chunk_end(png_ptr);
1496
#ifdef PNG_WRITE_hIST_SUPPORTED
1497
/* Write the histogram */
1499
png_write_hIST(png_structrp png_ptr, png_const_uint_16p hist, int num_hist)
1504
png_debug(1, "in png_write_hIST");
1506
if (num_hist > (int)png_ptr->num_palette)
1508
png_debug2(3, "num_hist = %d, num_palette = %d", num_hist,
1509
png_ptr->num_palette);
1511
png_warning(png_ptr, "Invalid number of histogram entries specified");
1515
png_write_chunk_header(png_ptr, png_hIST, (png_uint_32)(num_hist * 2));
1517
for (i = 0; i < num_hist; i++)
1519
png_save_uint_16(buf, hist[i]);
1520
png_write_chunk_data(png_ptr, buf, 2);
1523
png_write_chunk_end(png_ptr);
1527
#ifdef PNG_WRITE_tEXt_SUPPORTED
1528
/* Write a tEXt chunk */
1530
png_write_tEXt(png_structrp png_ptr, png_const_charp key, png_const_charp text,
1533
png_uint_32 key_len;
1534
png_byte new_key[80];
1536
png_debug(1, "in png_write_tEXt");
1538
key_len = png_check_keyword(png_ptr, key, new_key);
1541
png_error(png_ptr, "tEXt: invalid keyword");
1543
if (text == NULL || *text == '\0')
1547
text_len = strlen(text);
1549
if (text_len > PNG_UINT_31_MAX - (key_len+1))
1550
png_error(png_ptr, "tEXt: text too long");
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));
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.
1561
png_write_chunk_data(png_ptr, new_key, key_len + 1);
1564
png_write_chunk_data(png_ptr, (png_const_bytep)text, text_len);
1566
png_write_chunk_end(png_ptr);
1570
#ifdef PNG_WRITE_zTXt_SUPPORTED
1571
/* Write a compressed text chunk */
1573
png_write_zTXt(png_structrp png_ptr, png_const_charp key, png_const_charp text,
1576
png_uint_32 key_len;
1577
png_byte new_key[81];
1578
compression_state comp;
1580
png_debug(1, "in png_write_zTXt");
1582
if (compression == PNG_TEXT_COMPRESSION_NONE)
1584
png_write_tEXt(png_ptr, key, text, 0);
1588
if (compression != PNG_TEXT_COMPRESSION_zTXt)
1589
png_error(png_ptr, "zTXt: invalid compression type");
1591
key_len = png_check_keyword(png_ptr, key, new_key);
1594
png_error(png_ptr, "zTXt: invalid keyword");
1596
/* Add the compression method and 1 for the keyword separator. */
1597
new_key[++key_len] = PNG_COMPRESSION_TYPE_BASE;
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));
1604
if (png_text_compress(png_ptr, png_zTXt, &comp, key_len) != Z_OK)
1605
png_error(png_ptr, png_ptr->zstream.msg);
1607
/* Write start of chunk */
1608
png_write_chunk_header(png_ptr, png_zTXt, key_len + comp.output_len);
1611
png_write_chunk_data(png_ptr, new_key, key_len);
1613
/* Write the compressed data */
1614
png_write_compressed_data_out(png_ptr, &comp);
1616
/* Close the chunk */
1617
png_write_chunk_end(png_ptr);
1621
#ifdef PNG_WRITE_iTXt_SUPPORTED
1622
/* Write an iTXt chunk */
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)
1627
png_uint_32 key_len, prefix_len;
1628
size_t lang_len, lang_key_len;
1629
png_byte new_key[82];
1630
compression_state comp;
1632
png_debug(1, "in png_write_iTXt");
1634
key_len = png_check_keyword(png_ptr, key, new_key);
1637
png_error(png_ptr, "iTXt: invalid keyword");
1639
/* Set the compression flag */
1640
switch (compression)
1642
case PNG_ITXT_COMPRESSION_NONE:
1643
case PNG_TEXT_COMPRESSION_NONE:
1644
compression = new_key[++key_len] = 0; /* no compression */
1647
case PNG_TEXT_COMPRESSION_zTXt:
1648
case PNG_ITXT_COMPRESSION_zTXt:
1649
compression = new_key[++key_len] = 1; /* compressed */
1653
png_error(png_ptr, "iTXt: invalid compression");
1656
new_key[++key_len] = PNG_COMPRESSION_TYPE_BASE;
1657
++key_len; /* for the keywod separator */
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
1665
* The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1667
* TODO: validate the language tag correctly (see the spec.)
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 */
1675
prefix_len = key_len;
1676
if (lang_len > PNG_UINT_31_MAX-prefix_len)
1677
prefix_len = PNG_UINT_31_MAX;
1679
prefix_len = (png_uint_32)(prefix_len + lang_len);
1681
if (lang_key_len > PNG_UINT_31_MAX-prefix_len)
1682
prefix_len = PNG_UINT_31_MAX;
1684
prefix_len = (png_uint_32)(prefix_len + lang_key_len);
1686
png_text_compress_init(&comp, (png_const_bytep)text, strlen(text));
1688
if (compression != 0)
1690
if (png_text_compress(png_ptr, png_iTXt, &comp, prefix_len) != Z_OK)
1691
png_error(png_ptr, png_ptr->zstream.msg);
1696
if (comp.input_len > PNG_UINT_31_MAX-prefix_len)
1697
png_error(png_ptr, "iTXt: uncompressed text too long");
1699
/* So the string will fit in a chunk: */
1700
comp.output_len = (png_uint_32)/*SAFE*/comp.input_len;
1703
png_write_chunk_header(png_ptr, png_iTXt, comp.output_len + prefix_len);
1705
png_write_chunk_data(png_ptr, new_key, key_len);
1707
png_write_chunk_data(png_ptr, (png_const_bytep)lang, lang_len);
1709
png_write_chunk_data(png_ptr, (png_const_bytep)lang_key, lang_key_len);
1711
if (compression != 0)
1712
png_write_compressed_data_out(png_ptr, &comp);
1715
png_write_chunk_data(png_ptr, (png_const_bytep)text, comp.output_len);
1717
png_write_chunk_end(png_ptr);
1721
#ifdef PNG_WRITE_oFFs_SUPPORTED
1722
/* Write the oFFs chunk */
1724
png_write_oFFs(png_structrp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
1729
png_debug(1, "in png_write_oFFs");
1731
if (unit_type >= PNG_OFFSET_LAST)
1732
png_warning(png_ptr, "Unrecognized unit type for oFFs chunk");
1734
png_save_int_32(buf, x_offset);
1735
png_save_int_32(buf + 4, y_offset);
1736
buf[8] = (png_byte)unit_type;
1738
png_write_complete_chunk(png_ptr, png_oFFs, buf, 9);
1741
#ifdef PNG_WRITE_pCAL_SUPPORTED
1742
/* Write the pCAL chunk (described in the PNG extensions document) */
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,
1748
png_uint_32 purpose_len;
1749
size_t units_len, total_len;
1752
png_byte new_purpose[80];
1755
png_debug1(1, "in png_write_pCAL (%d parameters)", nparams);
1757
if (type >= PNG_EQUATION_LAST)
1758
png_error(png_ptr, "Unrecognized equation type for pCAL chunk");
1760
purpose_len = png_check_keyword(png_ptr, purpose, new_purpose);
1762
if (purpose_len == 0)
1763
png_error(png_ptr, "pCAL: invalid keyword");
1765
++purpose_len; /* terminator */
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;
1772
params_len = (size_t *)png_malloc(png_ptr,
1773
(png_alloc_size_t)((png_alloc_size_t)nparams * (sizeof (size_t))));
1775
/* Find the length of each parameter, making sure we don't count the
1776
* null terminator for the last parameter.
1778
for (i = 0; i < nparams; i++)
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];
1786
png_debug1(3, "pCAL total length = %d", (int)total_len);
1787
png_write_chunk_header(png_ptr, png_pCAL, (png_uint_32)total_len);
1788
png_write_chunk_data(png_ptr, new_purpose, purpose_len);
1789
png_save_int_32(buf, X0);
1790
png_save_int_32(buf + 4, X1);
1791
buf[8] = (png_byte)type;
1792
buf[9] = (png_byte)nparams;
1793
png_write_chunk_data(png_ptr, buf, 10);
1794
png_write_chunk_data(png_ptr, (png_const_bytep)units, (size_t)units_len);
1796
for (i = 0; i < nparams; i++)
1798
png_write_chunk_data(png_ptr, (png_const_bytep)params[i], params_len[i]);
1801
png_free(png_ptr, params_len);
1802
png_write_chunk_end(png_ptr);
1806
#ifdef PNG_WRITE_sCAL_SUPPORTED
1807
/* Write the sCAL chunk */
1809
png_write_sCAL_s(png_structrp png_ptr, int unit, png_const_charp width,
1810
png_const_charp height)
1813
size_t wlen, hlen, total_len;
1815
png_debug(1, "in png_write_sCAL_s");
1817
wlen = strlen(width);
1818
hlen = strlen(height);
1819
total_len = wlen + hlen + 2;
1823
png_warning(png_ptr, "Can't write sCAL (buffer too small)");
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 */
1831
png_debug1(3, "sCAL total length = %u", (unsigned int)total_len);
1832
png_write_complete_chunk(png_ptr, png_sCAL, buf, total_len);
1836
#ifdef PNG_WRITE_pHYs_SUPPORTED
1837
/* Write the pHYs chunk */
1839
png_write_pHYs(png_structrp png_ptr, png_uint_32 x_pixels_per_unit,
1840
png_uint_32 y_pixels_per_unit,
1845
png_debug(1, "in png_write_pHYs");
1847
if (unit_type >= PNG_RESOLUTION_LAST)
1848
png_warning(png_ptr, "Unrecognized unit type for pHYs chunk");
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;
1854
png_write_complete_chunk(png_ptr, png_pHYs, buf, 9);
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.
1863
png_write_tIME(png_structrp png_ptr, png_const_timep mod_time)
1867
png_debug(1, "in png_write_tIME");
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)
1873
png_warning(png_ptr, "Invalid time specified for tIME chunk");
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;
1884
png_write_complete_chunk(png_ptr, png_tIME, buf, 7);
1888
/* Initializes the row writing capability of libpng */
1890
png_write_start_row(png_structrp png_ptr)
1892
#ifdef PNG_WRITE_INTERLACING_SUPPORTED
1893
/* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1895
/* Start of interlace block */
1896
static const png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};1898
/* Offset to next interlace block */
1899
static const png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};1901
/* Start of interlace block in the y direction */
1902
static const png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};1904
/* Offset to next interlace block in the y direction */
1905
static const png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};1908
png_alloc_size_t buf_size;
1909
int usr_pixel_depth;
1911
#ifdef PNG_WRITE_FILTER_SUPPORTED
1915
png_debug(1, "in png_write_start_row");
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;
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;
1924
/* Set up row buffer */
1925
png_ptr->row_buf = png_voidcast(png_bytep, png_malloc(png_ptr, buf_size));
1927
png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE;
1929
#ifdef PNG_WRITE_FILTER_SUPPORTED
1930
filters = png_ptr->do_filter;
1932
if (png_ptr->height == 1)
1933
filters &= 0xff & ~(PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH);
1935
if (png_ptr->width == 1)
1936
filters &= 0xff & ~(PNG_FILTER_SUB|PNG_FILTER_AVG|PNG_FILTER_PAETH);
1939
filters = PNG_FILTER_NONE;
1941
png_ptr->do_filter = filters;
1943
if (((filters & (PNG_FILTER_SUB | PNG_FILTER_UP | PNG_FILTER_AVG |
1944
PNG_FILTER_PAETH)) != 0) && png_ptr->try_row == NULL)
1946
int num_filters = 0;
1948
png_ptr->try_row = png_voidcast(png_bytep, png_malloc(png_ptr, buf_size));
1950
if (filters & PNG_FILTER_SUB)
1953
if (filters & PNG_FILTER_UP)
1956
if (filters & PNG_FILTER_AVG)
1959
if (filters & PNG_FILTER_PAETH)
1962
if (num_filters > 1)
1963
png_ptr->tst_row = png_voidcast(png_bytep, png_malloc(png_ptr,
1967
/* We only need to keep the previous row if we are using one of the following
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 */
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)
1979
if ((png_ptr->transformations & PNG_INTERLACE) == 0)
1981
png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
1982
png_pass_ystart[0]) / png_pass_yinc[0];
1984
png_ptr->usr_width = (png_ptr->width + png_pass_inc[0] - 1 -
1985
png_pass_start[0]) / png_pass_inc[0];
1990
png_ptr->num_rows = png_ptr->height;
1991
png_ptr->usr_width = png_ptr->width;
1998
png_ptr->num_rows = png_ptr->height;
1999
png_ptr->usr_width = png_ptr->width;
2003
/* Internal use only. Called when finished processing a row of data. */
2005
png_write_finish_row(png_structrp png_ptr)
2007
#ifdef PNG_WRITE_INTERLACING_SUPPORTED
2008
/* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
2010
/* Start of interlace block */
2011
static const png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};2013
/* Offset to next interlace block */
2014
static const png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};2016
/* Start of interlace block in the y direction */
2017
static const png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};2019
/* Offset to next interlace block in the y direction */
2020
static const png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};2023
png_debug(1, "in png_write_finish_row");
2026
png_ptr->row_number++;
2028
/* See if we are done */
2029
if (png_ptr->row_number < png_ptr->num_rows)
2032
#ifdef PNG_WRITE_INTERLACING_SUPPORTED
2033
/* If interlaced, go to next pass */
2034
if (png_ptr->interlaced != 0)
2036
png_ptr->row_number = 0;
2037
if ((png_ptr->transformations & PNG_INTERLACE) != 0)
2044
/* Loop until we find a non-zero width or height pass */
2049
if (png_ptr->pass >= 7)
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];
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];
2062
if ((png_ptr->transformations & PNG_INTERLACE) != 0)
2065
} while (png_ptr->usr_width == 0 || png_ptr->num_rows == 0);
2069
/* Reset the row above the image for the next pass */
2070
if (png_ptr->pass < 7)
2072
if (png_ptr->prev_row != NULL)
2073
memset(png_ptr->prev_row, 0,
2074
PNG_ROWBYTES(png_ptr->usr_channels *
2075
png_ptr->usr_bit_depth, png_ptr->width) + 1);
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);
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.
2096
png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
2098
/* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
2100
/* Start of interlace block */
2101
static const png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};2103
/* Offset to next interlace block */
2104
static const png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};2106
png_debug(1, "in png_do_write_interlace");
2108
/* We don't have to do anything on the last pass (6) */
2111
/* Each pixel depth is handled separately */
2112
switch (row_info->pixel_depth)
2122
png_uint_32 row_width = row_info->width;
2128
for (i = png_pass_start[pass]; i < row_width;
2129
i += png_pass_inc[pass])
2131
sp = row + (size_t)(i >> 3);
2132
value = (int)(*sp >> (7 - (int)(i & 0x07))) & 0x01;
2133
d |= (value << shift);
2138
*dp++ = (png_byte)d;
2160
png_uint_32 row_width = row_info->width;
2166
for (i = png_pass_start[pass]; i < row_width;
2167
i += png_pass_inc[pass])
2169
sp = row + (size_t)(i >> 2);
2170
value = (*sp >> ((3 - (int)(i & 0x03)) << 1)) & 0x03;
2171
d |= (value << shift);
2176
*dp++ = (png_byte)d;
2197
png_uint_32 row_width = row_info->width;
2202
for (i = png_pass_start[pass]; i < row_width;
2203
i += png_pass_inc[pass])
2205
sp = row + (size_t)(i >> 1);
2206
value = (*sp >> ((1 - (int)(i & 0x01)) << 2)) & 0x0f;
2207
d |= (value << shift);
2212
*dp++ = (png_byte)d;
2230
png_uint_32 row_width = row_info->width;
2233
/* Start at the beginning */
2236
/* Find out how many bytes each pixel takes up */
2237
pixel_bytes = (row_info->pixel_depth >> 3);
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])
2243
/* Find out where the original pixel is */
2244
sp = row + (size_t)i * pixel_bytes;
2246
/* Move the pixel */
2248
memcpy(dp, sp, pixel_bytes);
2256
/* Set new row width */
2257
row_info->width = (row_info->width +
2258
png_pass_inc[pass] - 1 -
2259
png_pass_start[pass]) /
2262
row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
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
2273
static void /* PRIVATE */
2274
png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row,
2277
#ifdef PNG_WRITE_FILTER_SUPPORTED
2278
static size_t /* PRIVATE */
2279
png_setup_sub_row(png_structrp png_ptr, png_uint_32 bpp,
2280
size_t row_bytes, size_t lmins)
2282
png_bytep rp, dp, lp;
2287
png_ptr->try_row[0] = PNG_FILTER_VALUE_SUB;
2289
for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1; i < bpp;
2294
sum += 128 - abs((int)v - 128);
2296
sum += (v < 128) ? v : 256 - v;
2300
for (lp = png_ptr->row_buf + 1; i < row_bytes;
2301
i++, rp++, lp++, dp++)
2303
v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
2305
sum += 128 - abs((int)v - 128);
2307
sum += (v < 128) ? v : 256 - v;
2310
if (sum > lmins) /* We are already worse, don't continue. */
2317
static void /* PRIVATE */
2318
png_setup_sub_row_only(png_structrp png_ptr, png_uint_32 bpp,
2321
png_bytep rp, dp, lp;
2324
png_ptr->try_row[0] = PNG_FILTER_VALUE_SUB;
2326
for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1; i < bpp;
2332
for (lp = png_ptr->row_buf + 1; i < row_bytes;
2333
i++, rp++, lp++, dp++)
2335
*dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
2339
static size_t /* PRIVATE */
2340
png_setup_up_row(png_structrp png_ptr, size_t row_bytes, size_t lmins)
2342
png_bytep rp, dp, pp;
2347
png_ptr->try_row[0] = PNG_FILTER_VALUE_UP;
2349
for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1,
2350
pp = png_ptr->prev_row + 1; i < row_bytes;
2351
i++, rp++, pp++, dp++)
2353
v = *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
2355
sum += 128 - abs((int)v - 128);
2357
sum += (v < 128) ? v : 256 - v;
2360
if (sum > lmins) /* We are already worse, don't continue. */
2366
static void /* PRIVATE */
2367
png_setup_up_row_only(png_structrp png_ptr, size_t row_bytes)
2369
png_bytep rp, dp, pp;
2372
png_ptr->try_row[0] = PNG_FILTER_VALUE_UP;
2374
for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1,
2375
pp = png_ptr->prev_row + 1; i < row_bytes;
2376
i++, rp++, pp++, dp++)
2378
*dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
2382
static size_t /* PRIVATE */
2383
png_setup_avg_row(png_structrp png_ptr, png_uint_32 bpp,
2384
size_t row_bytes, size_t lmins)
2386
png_bytep rp, dp, pp, lp;
2391
png_ptr->try_row[0] = PNG_FILTER_VALUE_AVG;
2393
for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1,
2394
pp = png_ptr->prev_row + 1; i < bpp; i++)
2396
v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
2399
sum += 128 - abs((int)v - 128);
2401
sum += (v < 128) ? v : 256 - v;
2405
for (lp = png_ptr->row_buf + 1; i < row_bytes; i++)
2407
v = *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
2411
sum += 128 - abs((int)v - 128);
2413
sum += (v < 128) ? v : 256 - v;
2416
if (sum > lmins) /* We are already worse, don't continue. */
2422
static void /* PRIVATE */
2423
png_setup_avg_row_only(png_structrp png_ptr, png_uint_32 bpp,
2426
png_bytep rp, dp, pp, lp;
2429
png_ptr->try_row[0] = PNG_FILTER_VALUE_AVG;
2431
for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1,
2432
pp = png_ptr->prev_row + 1; i < bpp; i++)
2434
*dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
2437
for (lp = png_ptr->row_buf + 1; i < row_bytes; i++)
2439
*dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
2444
static size_t /* PRIVATE */
2445
png_setup_paeth_row(png_structrp png_ptr, png_uint_32 bpp,
2446
size_t row_bytes, size_t lmins)
2448
png_bytep rp, dp, pp, cp, lp;
2453
png_ptr->try_row[0] = PNG_FILTER_VALUE_PAETH;
2455
for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1,
2456
pp = png_ptr->prev_row + 1; i < bpp; i++)
2458
v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2461
sum += 128 - abs((int)v - 128);
2463
sum += (v < 128) ? v : 256 - v;
2467
for (lp = png_ptr->row_buf + 1, cp = png_ptr->prev_row + 1; i < row_bytes;
2470
int a, b, c, pa, pb, pc, p;
2484
pa = p < 0 ? -p : p;
2485
pb = pc < 0 ? -pc : pc;
2486
pc = (p + pc) < 0 ? -(p + pc) : p + pc;
2489
p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
2491
v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
2494
sum += 128 - abs((int)v - 128);
2496
sum += (v < 128) ? v : 256 - v;
2499
if (sum > lmins) /* We are already worse, don't continue. */
2505
static void /* PRIVATE */
2506
png_setup_paeth_row_only(png_structrp png_ptr, png_uint_32 bpp,
2509
png_bytep rp, dp, pp, cp, lp;
2512
png_ptr->try_row[0] = PNG_FILTER_VALUE_PAETH;
2514
for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1,
2515
pp = png_ptr->prev_row + 1; i < bpp; i++)
2517
*dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2520
for (lp = png_ptr->row_buf + 1, cp = png_ptr->prev_row + 1; i < row_bytes;
2523
int a, b, c, pa, pb, pc, p;
2537
pa = p < 0 ? -p : p;
2538
pb = pc < 0 ? -pc : pc;
2539
pc = (p + pc) < 0 ? -(p + pc) : p + pc;
2542
p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
2544
*dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
2547
#endif /* WRITE_FILTER */
2550
png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
2552
#ifndef PNG_WRITE_FILTER_SUPPORTED
2553
png_write_filtered_row(png_ptr, png_ptr->row_buf, row_info->rowbytes+1);
2555
unsigned int filter_to_do = png_ptr->do_filter;
2560
size_t row_bytes = row_info->rowbytes;
2562
png_debug(1, "in png_write_find_filter");
2564
/* Find out how many bytes offset each pixel is */
2565
bpp = (row_info->pixel_depth + 7) >> 3;
2567
row_buf = png_ptr->row_buf;
2568
mins = PNG_SIZE_MAX - 256/* so we can detect potential overflow of the
2571
/* The prediction method we use is to find which method provides the
2572
* smallest value when summing the absolute values of the distances
2573
* from zero, using anything >= 128 as negative numbers. This is known
2574
* as the "minimum sum of absolute differences" heuristic. Other
2575
* heuristics are the "weighted minimum sum of absolute differences"
2576
* (experimental and can in theory improve compression), and the "zlib
2577
* predictive" method (not implemented yet), which does test compressions
2578
* of lines using different filter methods, and then chooses the
2579
* (series of) filter(s) that give minimum compressed data size (VERY
2580
* computationally expensive).
2582
* GRR 980525: consider also
2584
* (1) minimum sum of absolute differences from running average (i.e.,
2585
* keep running sum of non-absolute differences & count of bytes)
2586
* [track dispersion, too? restart average if dispersion too large?]
2588
* (1b) minimum sum of absolute differences from sliding average, probably
2589
* with window size <= deflate window (usually 32K)
2591
* (2) minimum sum of squared differences from zero or running average
2592
* (i.e., ~ root-mean-square approach)
2596
/* We don't need to test the 'no filter' case if this is the only filter
2597
* that has been chosen, as it doesn't actually do anything to the data.
2599
best_row = png_ptr->row_buf;
2601
if (PNG_SIZE_MAX/128 <= row_bytes)
2603
/* Overflow can occur in the calculation, just select the lowest set
2606
filter_to_do &= 0U-filter_to_do;
2608
else if ((filter_to_do & PNG_FILTER_NONE) != 0 &&
2609
filter_to_do != PNG_FILTER_NONE)
2611
/* Overflow not possible and multiple filters in the list, including the
2620
for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
2624
sum += 128 - abs((int)v - 128);
2626
sum += (v < 128) ? v : 256 - v;
2635
if (filter_to_do == PNG_FILTER_SUB)
2636
/* It's the only filter so no testing is needed */
2638
png_setup_sub_row_only(png_ptr, bpp, row_bytes);
2639
best_row = png_ptr->try_row;
2642
else if ((filter_to_do & PNG_FILTER_SUB) != 0)
2645
size_t lmins = mins;
2647
sum = png_setup_sub_row(png_ptr, bpp, row_bytes, lmins);
2652
best_row = png_ptr->try_row;
2653
if (png_ptr->tst_row != NULL)
2655
png_ptr->try_row = png_ptr->tst_row;
2656
png_ptr->tst_row = best_row;
2662
if (filter_to_do == PNG_FILTER_UP)
2664
png_setup_up_row_only(png_ptr, row_bytes);
2665
best_row = png_ptr->try_row;
2668
else if ((filter_to_do & PNG_FILTER_UP) != 0)
2671
size_t lmins = mins;
2673
sum = png_setup_up_row(png_ptr, row_bytes, lmins);
2678
best_row = png_ptr->try_row;
2679
if (png_ptr->tst_row != NULL)
2681
png_ptr->try_row = png_ptr->tst_row;
2682
png_ptr->tst_row = best_row;
2688
if (filter_to_do == PNG_FILTER_AVG)
2690
png_setup_avg_row_only(png_ptr, bpp, row_bytes);
2691
best_row = png_ptr->try_row;
2694
else if ((filter_to_do & PNG_FILTER_AVG) != 0)
2697
size_t lmins = mins;
2699
sum= png_setup_avg_row(png_ptr, bpp, row_bytes, lmins);
2704
best_row = png_ptr->try_row;
2705
if (png_ptr->tst_row != NULL)
2707
png_ptr->try_row = png_ptr->tst_row;
2708
png_ptr->tst_row = best_row;
2714
if (filter_to_do == PNG_FILTER_PAETH)
2716
png_setup_paeth_row_only(png_ptr, bpp, row_bytes);
2717
best_row = png_ptr->try_row;
2720
else if ((filter_to_do & PNG_FILTER_PAETH) != 0)
2723
size_t lmins = mins;
2725
sum = png_setup_paeth_row(png_ptr, bpp, row_bytes, lmins);
2729
best_row = png_ptr->try_row;
2730
if (png_ptr->tst_row != NULL)
2732
png_ptr->try_row = png_ptr->tst_row;
2733
png_ptr->tst_row = best_row;
2738
/* Do the actual writing of the filtered row data from the chosen filter. */
2739
png_write_filtered_row(png_ptr, best_row, row_info->rowbytes+1);
2741
#endif /* WRITE_FILTER */
2745
/* Do the actual writing of a previously filtered row. */
2747
png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row,
2748
size_t full_row_length/*includes filter byte*/)
2750
png_debug(1, "in png_write_filtered_row");
2752
png_debug1(2, "filter = %d", filtered_row[0]);
2754
png_compress_IDAT(png_ptr, filtered_row, full_row_length, Z_NO_FLUSH);
2756
#ifdef PNG_WRITE_FILTER_SUPPORTED
2757
/* Swap the current and previous rows */
2758
if (png_ptr->prev_row != NULL)
2762
tptr = png_ptr->prev_row;
2763
png_ptr->prev_row = png_ptr->row_buf;
2764
png_ptr->row_buf = tptr;
2766
#endif /* WRITE_FILTER */
2768
/* Finish row - updates counters and flushes zlib if last row */
2769
png_write_finish_row(png_ptr);
2771
#ifdef PNG_WRITE_FLUSH_SUPPORTED
2772
png_ptr->flush_rows++;
2774
if (png_ptr->flush_dist > 0 &&
2775
png_ptr->flush_rows >= png_ptr->flush_dist)
2777
png_write_flush(png_ptr);
2779
#endif /* WRITE_FLUSH */