2 /* pngwutil.c - utilities to write a PNG file
4 * Last changed in libpng 1.5.14 [January 24, 2013]
5 * Copyright (c) 1998-2013 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.)
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
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
20 * 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)
26 buf[0] = (png_byte)((i >> 24) & 0xff);
27 buf[1] = (png_byte)((i >> 16) & 0xff);
28 buf[2] = (png_byte)((i >> 8) & 0xff);
29 buf[3] = (png_byte)(i & 0xff);
32 #ifdef PNG_SAVE_INT_32_SUPPORTED
33 /* The png_save_int_32 function assumes integers are stored in two's
34 * complement format. If this isn't the case, then this routine needs to
35 * be modified to write data in two's complement format. Note that,
36 * the following works correctly even if png_int_32 has more than 32 bits
37 * (compare the more complex code required on read for sign extention.)
40 png_save_int_32(png_bytep buf, png_int_32 i)
42 buf[0] = (png_byte)((i >> 24) & 0xff);
43 buf[1] = (png_byte)((i >> 16) & 0xff);
44 buf[2] = (png_byte)((i >> 8) & 0xff);
45 buf[3] = (png_byte)(i & 0xff);
49 /* Place a 16-bit number into a buffer in PNG byte order.
50 * The parameter is declared unsigned int, not png_uint_16,
51 * just to avoid potential problems on pre-ANSI C compilers.
54 png_save_uint_16(png_bytep buf, unsigned int i)
56 buf[0] = (png_byte)((i >> 8) & 0xff);
57 buf[1] = (png_byte)(i & 0xff);
61 /* Simple function to write the signature. If we have already written
62 * the magic bytes of the signature, or more likely, the PNG stream is
63 * being embedded into another stream and doesn't need its own signature,
64 * we should call png_set_sig_bytes() to tell libpng how many of the
65 * bytes have already been written.
68 png_write_sig(png_structp png_ptr)
70 png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
72 #ifdef PNG_IO_STATE_SUPPORTED
73 /* Inform the I/O callback that the signature is being written */
74 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_SIGNATURE;
77 /* Write the rest of the 8 byte signature */
78 png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes],
79 (png_size_t)(8 - png_ptr->sig_bytes));
81 if (png_ptr->sig_bytes < 3)
82 png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
85 /* Write the start of a PNG chunk. The type is the chunk type.
86 * The total_length is the sum of the lengths of all the data you will be
87 * passing in png_write_chunk_data().
90 png_write_chunk_header(png_structp png_ptr, png_uint_32 chunk_name,
95 #if defined(PNG_DEBUG) && (PNG_DEBUG > 0)
96 PNG_CSTRING_FROM_CHUNK(buf, chunk_name);
97 png_debug2(0, "Writing %s chunk, length = %lu", buf, (unsigned long)length);
103 #ifdef PNG_IO_STATE_SUPPORTED
104 /* Inform the I/O callback that the chunk header is being written.
105 * PNG_IO_CHUNK_HDR requires a single I/O call.
107 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_HDR;
110 /* Write the length and the chunk name */
111 png_save_uint_32(buf, length);
112 png_save_uint_32(buf + 4, chunk_name);
113 png_write_data(png_ptr, buf, 8);
115 /* Put the chunk name into png_ptr->chunk_name */
116 png_ptr->chunk_name = chunk_name;
118 /* Reset the crc and run it over the chunk name */
119 png_reset_crc(png_ptr);
121 png_calculate_crc(png_ptr, buf + 4, 4);
123 #ifdef PNG_IO_STATE_SUPPORTED
124 /* Inform the I/O callback that chunk data will (possibly) be written.
125 * PNG_IO_CHUNK_DATA does NOT require a specific number of I/O calls.
127 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_DATA;
132 png_write_chunk_start(png_structp png_ptr, png_const_bytep chunk_string,
135 png_write_chunk_header(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), length);
138 /* Write the data of a PNG chunk started with png_write_chunk_header().
139 * Note that multiple calls to this function are allowed, and that the
140 * sum of the lengths from these calls *must* add up to the total_length
141 * given to png_write_chunk_header().
144 png_write_chunk_data(png_structp png_ptr, png_const_bytep data,
147 /* Write the data, and run the CRC over it */
151 if (data != NULL && length > 0)
153 png_write_data(png_ptr, data, length);
155 /* Update the CRC after writing the data,
156 * in case that the user I/O routine alters it.
158 png_calculate_crc(png_ptr, data, length);
162 /* Finish a chunk started with png_write_chunk_header(). */
164 png_write_chunk_end(png_structp png_ptr)
168 if (png_ptr == NULL) return;
170 #ifdef PNG_IO_STATE_SUPPORTED
171 /* Inform the I/O callback that the chunk CRC is being written.
172 * PNG_IO_CHUNK_CRC requires a single I/O function call.
174 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_CRC;
177 /* Write the crc in a single operation */
178 png_save_uint_32(buf, png_ptr->crc);
180 png_write_data(png_ptr, buf, (png_size_t)4);
183 /* Write a PNG chunk all at once. The type is an array of ASCII characters
184 * representing the chunk name. The array must be at least 4 bytes in
185 * length, and does not need to be null terminated. To be safe, pass the
186 * pre-defined chunk names here, and if you need a new one, define it
187 * where the others are defined. The length is the length of the data.
188 * All the data must be present. If that is not possible, use the
189 * png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end()
193 png_write_complete_chunk(png_structp png_ptr, png_uint_32 chunk_name,
194 png_const_bytep data, png_size_t length)
199 /* On 64 bit architectures 'length' may not fit in a png_uint_32. */
200 if (length > PNG_UINT_32_MAX)
201 png_error(png_ptr, "length exceeds PNG maxima");
203 png_write_chunk_header(png_ptr, chunk_name, (png_uint_32)length);
204 png_write_chunk_data(png_ptr, data, length);
205 png_write_chunk_end(png_ptr);
208 /* This is the API that calls the internal function above. */
210 png_write_chunk(png_structp png_ptr, png_const_bytep chunk_string,
211 png_const_bytep data, png_size_t length)
213 png_write_complete_chunk(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), data,
217 /* Initialize the compressor for the appropriate type of compression. */
219 png_zlib_claim(png_structp png_ptr, png_uint_32 state)
221 if (!(png_ptr->zlib_state & PNG_ZLIB_IN_USE))
223 /* If already initialized for 'state' do not re-init. */
224 if (png_ptr->zlib_state != state)
227 png_const_charp who = "-";
229 /* If actually initialized for another state do a deflateEnd. */
230 if (png_ptr->zlib_state != PNG_ZLIB_UNINITIALIZED)
232 ret = deflateEnd(&png_ptr->zstream);
234 png_ptr->zlib_state = PNG_ZLIB_UNINITIALIZED;
237 /* zlib itself detects an incomplete state on deflateEnd */
238 if (ret == Z_OK) switch (state)
240 # ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
241 case PNG_ZLIB_FOR_TEXT:
242 ret = deflateInit2(&png_ptr->zstream,
243 png_ptr->zlib_text_level, png_ptr->zlib_text_method,
244 png_ptr->zlib_text_window_bits,
245 png_ptr->zlib_text_mem_level, png_ptr->zlib_text_strategy);
250 case PNG_ZLIB_FOR_IDAT:
251 ret = deflateInit2(&png_ptr->zstream, png_ptr->zlib_level,
252 png_ptr->zlib_method, png_ptr->zlib_window_bits,
253 png_ptr->zlib_mem_level, png_ptr->zlib_strategy);
258 png_error(png_ptr, "invalid zlib state");
262 png_ptr->zlib_state = state;
264 else /* an error in deflateEnd or deflateInit2 */
269 pos = png_safecat(msg, sizeof msg, pos,
270 "zlib failed to initialize compressor (");
271 pos = png_safecat(msg, sizeof msg, pos, who);
275 case Z_VERSION_ERROR:
276 pos = png_safecat(msg, sizeof msg, pos, ") version error");
280 pos = png_safecat(msg, sizeof msg, pos, ") stream error");
284 pos = png_safecat(msg, sizeof msg, pos, ") memory error");
288 pos = png_safecat(msg, sizeof msg, pos, ") unknown error");
292 png_error(png_ptr, msg);
296 /* Here on success, claim the zstream: */
297 png_ptr->zlib_state |= PNG_ZLIB_IN_USE;
301 png_error(png_ptr, "zstream already in use (internal error)");
304 /* The opposite: release the stream. It is also reset, this API will warn on
305 * error but will not fail.
308 png_zlib_release(png_structp png_ptr)
310 if (png_ptr->zlib_state & PNG_ZLIB_IN_USE)
312 int ret = deflateReset(&png_ptr->zstream);
314 png_ptr->zlib_state &= ~PNG_ZLIB_IN_USE;
319 PNG_WARNING_PARAMETERS(p)
323 case Z_VERSION_ERROR:
340 png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_d, ret);
341 png_warning_parameter(p, 2, err);
343 if (png_ptr->zstream.msg)
344 err = png_ptr->zstream.msg;
346 err = "[no zlib message]";
348 png_warning_parameter(p, 3, err);
350 png_formatted_warning(png_ptr, p,
351 "zlib failed to reset compressor: @1(@2): @3");
356 png_warning(png_ptr, "zstream not in use (internal error)");
359 #ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
360 /* This pair of functions encapsulates the operation of (a) compressing a
361 * text string, and (b) issuing it later as a series of chunk data writes.
362 * The compression_state structure is shared context for these functions
363 * set up by the caller in order to make the whole mess thread-safe.
368 png_const_bytep input; /* The uncompressed input data */
369 png_size_t input_len; /* Its length */
370 int num_output_ptr; /* Number of output pointers used */
371 int max_output_ptr; /* Size of output_ptr */
372 png_bytep *output_ptr; /* Array of pointers to output */
375 /* Compress given text into storage in the png_ptr structure */
376 static int /* PRIVATE */
377 png_text_compress(png_structp png_ptr,
378 png_const_charp text, png_size_t text_len, int compression,
379 compression_state *comp)
383 comp->num_output_ptr = 0;
384 comp->max_output_ptr = 0;
385 comp->output_ptr = NULL;
387 comp->input_len = text_len;
389 /* We may just want to pass the text right through */
390 if (compression == PNG_TEXT_COMPRESSION_NONE)
392 comp->input = (png_const_bytep)text;
393 return((int)text_len);
396 if (compression >= PNG_TEXT_COMPRESSION_LAST)
398 PNG_WARNING_PARAMETERS(p)
400 png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_d,
402 png_formatted_warning(png_ptr, p, "Unknown compression type @1");
405 /* We can't write the chunk until we find out how much data we have,
406 * which means we need to run the compressor first and save the
407 * output. This shouldn't be a problem, as the vast majority of
408 * comments should be reasonable, but we will set up an array of
409 * malloc'd pointers to be sure.
411 * If we knew the application was well behaved, we could simplify this
412 * greatly by assuming we can always malloc an output buffer large
413 * enough to hold the compressed text ((1001 * text_len / 1000) + 12)
414 * and malloc this directly. The only time this would be a bad idea is
415 * if we can't malloc more than 64K and we have 64K of random input
416 * data, or if the input string is incredibly large (although this
417 * wouldn't cause a failure, just a slowdown due to swapping).
419 png_zlib_claim(png_ptr, PNG_ZLIB_FOR_TEXT);
421 /* Set up the compression buffers */
422 /* TODO: the following cast hides a potential overflow problem. */
423 png_ptr->zstream.avail_in = (uInt)text_len;
425 /* NOTE: assume zlib doesn't overwrite the input */
426 png_ptr->zstream.next_in = (Bytef *)text;
427 png_ptr->zstream.avail_out = png_ptr->zbuf_size;
428 png_ptr->zstream.next_out = png_ptr->zbuf;
430 /* This is the same compression loop as in png_write_row() */
433 /* Compress the data */
434 ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
439 if (png_ptr->zstream.msg != NULL)
440 png_error(png_ptr, png_ptr->zstream.msg);
443 png_error(png_ptr, "zlib error");
446 /* Check to see if we need more room */
447 if (!(png_ptr->zstream.avail_out))
449 /* Make sure the output array has room */
450 if (comp->num_output_ptr >= comp->max_output_ptr)
454 old_max = comp->max_output_ptr;
455 comp->max_output_ptr = comp->num_output_ptr + 4;
456 if (comp->output_ptr != NULL)
460 old_ptr = comp->output_ptr;
462 comp->output_ptr = (png_bytepp)png_malloc(png_ptr,
463 (comp->max_output_ptr * png_sizeof(png_bytep)));
465 png_memcpy(comp->output_ptr, old_ptr, old_max
466 * png_sizeof(png_bytep));
468 png_free(png_ptr, old_ptr);
471 comp->output_ptr = (png_bytepp)png_malloc(png_ptr,
472 (comp->max_output_ptr * png_sizeof(png_bytep)));
476 comp->output_ptr[comp->num_output_ptr] =
477 (png_bytep)png_malloc(png_ptr, png_ptr->zbuf_size);
479 png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
482 comp->num_output_ptr++;
484 /* and reset the buffer */
485 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
486 png_ptr->zstream.next_out = png_ptr->zbuf;
488 /* Continue until we don't have any more to compress */
489 } while (png_ptr->zstream.avail_in);
491 /* Finish the compression */
494 /* Tell zlib we are finished */
495 ret = deflate(&png_ptr->zstream, Z_FINISH);
499 /* Check to see if we need more room */
500 if (!(png_ptr->zstream.avail_out))
502 /* Check to make sure our output array has room */
503 if (comp->num_output_ptr >= comp->max_output_ptr)
507 old_max = comp->max_output_ptr;
508 comp->max_output_ptr = comp->num_output_ptr + 4;
509 if (comp->output_ptr != NULL)
513 old_ptr = comp->output_ptr;
515 /* This could be optimized to realloc() */
516 comp->output_ptr = (png_bytepp)png_malloc(png_ptr,
517 (png_alloc_size_t)(comp->max_output_ptr *
518 png_sizeof(png_charp)));
520 png_memcpy(comp->output_ptr, old_ptr,
521 old_max * png_sizeof(png_charp));
523 png_free(png_ptr, old_ptr);
527 comp->output_ptr = (png_bytepp)png_malloc(png_ptr,
528 (png_alloc_size_t)(comp->max_output_ptr *
529 png_sizeof(png_charp)));
533 comp->output_ptr[comp->num_output_ptr] =
534 (png_bytep)png_malloc(png_ptr,
535 (png_alloc_size_t)png_ptr->zbuf_size);
537 png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
540 comp->num_output_ptr++;
542 /* and reset the buffer pointers */
543 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
544 png_ptr->zstream.next_out = png_ptr->zbuf;
547 else if (ret != Z_STREAM_END)
549 /* We got an error */
550 if (png_ptr->zstream.msg != NULL)
551 png_error(png_ptr, png_ptr->zstream.msg);
554 png_error(png_ptr, "zlib error");
556 } while (ret != Z_STREAM_END);
558 /* Text length is number of buffers plus last buffer */
559 text_len = png_ptr->zbuf_size * comp->num_output_ptr;
561 if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
562 text_len += png_ptr->zbuf_size - (png_size_t)png_ptr->zstream.avail_out;
564 return((int)text_len);
567 /* Ship the compressed text out via chunk writes */
568 static void /* PRIVATE */
569 png_write_compressed_data_out(png_structp png_ptr, compression_state *comp,
574 /* Handle the no-compression case */
577 png_write_chunk_data(png_ptr, comp->input, data_len);
582 #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
583 /* The zbuf_size test is because the code below doesn't work if zbuf_size is
584 * '1'; simply skip it to avoid memory overwrite.
586 if (data_len >= 2 && comp->input_len < 16384 && png_ptr->zbuf_size > 1)
588 unsigned int z_cmf; /* zlib compression method and flags */
590 /* Optimize the CMF field in the zlib stream. This hack of the zlib
591 * stream is compliant to the stream specification.
594 if (comp->num_output_ptr)
595 z_cmf = comp->output_ptr[0][0];
597 z_cmf = png_ptr->zbuf[0];
599 if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
601 unsigned int z_cinfo;
602 unsigned int half_z_window_size;
603 png_size_t uncompressed_text_size = comp->input_len;
605 z_cinfo = z_cmf >> 4;
606 half_z_window_size = 1 << (z_cinfo + 7);
608 while (uncompressed_text_size <= half_z_window_size &&
609 half_z_window_size >= 256)
612 half_z_window_size >>= 1;
615 z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
617 if (comp->num_output_ptr)
620 if (comp->output_ptr[0][0] != z_cmf)
624 comp->output_ptr[0][0] = (png_byte)z_cmf;
625 tmp = comp->output_ptr[0][1] & 0xe0;
626 tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
627 comp->output_ptr[0][1] = (png_byte)tmp;
634 png_ptr->zbuf[0] = (png_byte)z_cmf;
635 tmp = png_ptr->zbuf[1] & 0xe0;
636 tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
637 png_ptr->zbuf[1] = (png_byte)tmp;
643 "Invalid zlib compression method or flags in non-IDAT chunk");
645 #endif /* PNG_WRITE_OPTIMIZE_CMF_SUPPORTED */
647 /* Write saved output buffers, if any */
648 for (i = 0; i < comp->num_output_ptr; i++)
650 png_write_chunk_data(png_ptr, comp->output_ptr[i],
651 (png_size_t)png_ptr->zbuf_size);
653 png_free(png_ptr, comp->output_ptr[i]);
656 if (comp->max_output_ptr != 0)
657 png_free(png_ptr, comp->output_ptr);
659 /* Write anything left in zbuf */
660 if (png_ptr->zstream.avail_out < (png_uint_32)png_ptr->zbuf_size)
661 png_write_chunk_data(png_ptr, png_ptr->zbuf,
662 (png_size_t)(png_ptr->zbuf_size - png_ptr->zstream.avail_out));
664 /* Reset zlib for another zTXt/iTXt or image data */
665 png_zlib_release(png_ptr);
667 #endif /* PNG_WRITE_COMPRESSED_TEXT_SUPPORTED */
669 /* Write the IHDR chunk, and update the png_struct with the necessary
670 * information. Note that the rest of this code depends upon this
671 * information being correct.
674 png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
675 int bit_depth, int color_type, int compression_type, int filter_type,
678 png_byte buf[13]; /* Buffer to store the IHDR info */
680 png_debug(1, "in png_write_IHDR");
682 /* Check that we have valid input data from the application info */
685 case PNG_COLOR_TYPE_GRAY:
692 #ifdef PNG_WRITE_16BIT_SUPPORTED
695 png_ptr->channels = 1; break;
699 "Invalid bit depth for grayscale image");
703 case PNG_COLOR_TYPE_RGB:
704 #ifdef PNG_WRITE_16BIT_SUPPORTED
705 if (bit_depth != 8 && bit_depth != 16)
709 png_error(png_ptr, "Invalid bit depth for RGB image");
711 png_ptr->channels = 3;
714 case PNG_COLOR_TYPE_PALETTE:
721 png_ptr->channels = 1;
725 png_error(png_ptr, "Invalid bit depth for paletted image");
729 case PNG_COLOR_TYPE_GRAY_ALPHA:
730 if (bit_depth != 8 && bit_depth != 16)
731 png_error(png_ptr, "Invalid bit depth for grayscale+alpha image");
733 png_ptr->channels = 2;
736 case PNG_COLOR_TYPE_RGB_ALPHA:
737 #ifdef PNG_WRITE_16BIT_SUPPORTED
738 if (bit_depth != 8 && bit_depth != 16)
742 png_error(png_ptr, "Invalid bit depth for RGBA image");
744 png_ptr->channels = 4;
748 png_error(png_ptr, "Invalid image color type specified");
751 if (compression_type != PNG_COMPRESSION_TYPE_BASE)
753 png_warning(png_ptr, "Invalid compression type specified");
754 compression_type = PNG_COMPRESSION_TYPE_BASE;
757 /* Write filter_method 64 (intrapixel differencing) only if
758 * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
759 * 2. Libpng did not write a PNG signature (this filter_method is only
760 * used in PNG datastreams that are embedded in MNG datastreams) and
761 * 3. The application called png_permit_mng_features with a mask that
762 * included PNG_FLAG_MNG_FILTER_64 and
763 * 4. The filter_method is 64 and
764 * 5. The color_type is RGB or RGBA
767 #ifdef PNG_MNG_FEATURES_SUPPORTED
768 !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
769 ((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE) == 0) &&
770 (color_type == PNG_COLOR_TYPE_RGB ||
771 color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&
772 (filter_type == PNG_INTRAPIXEL_DIFFERENCING)) &&
774 filter_type != PNG_FILTER_TYPE_BASE)
776 png_warning(png_ptr, "Invalid filter type specified");
777 filter_type = PNG_FILTER_TYPE_BASE;
780 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
781 if (interlace_type != PNG_INTERLACE_NONE &&
782 interlace_type != PNG_INTERLACE_ADAM7)
784 png_warning(png_ptr, "Invalid interlace type specified");
785 interlace_type = PNG_INTERLACE_ADAM7;
788 interlace_type=PNG_INTERLACE_NONE;
791 /* Save the relevent information */
792 png_ptr->bit_depth = (png_byte)bit_depth;
793 png_ptr->color_type = (png_byte)color_type;
794 png_ptr->interlaced = (png_byte)interlace_type;
795 #ifdef PNG_MNG_FEATURES_SUPPORTED
796 png_ptr->filter_type = (png_byte)filter_type;
798 png_ptr->compression_type = (png_byte)compression_type;
799 png_ptr->width = width;
800 png_ptr->height = height;
802 png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels);
803 png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width);
804 /* Set the usr info, so any transformations can modify it */
805 png_ptr->usr_width = png_ptr->width;
806 png_ptr->usr_bit_depth = png_ptr->bit_depth;
807 png_ptr->usr_channels = png_ptr->channels;
809 /* Pack the header information into the buffer */
810 png_save_uint_32(buf, width);
811 png_save_uint_32(buf + 4, height);
812 buf[8] = (png_byte)bit_depth;
813 buf[9] = (png_byte)color_type;
814 buf[10] = (png_byte)compression_type;
815 buf[11] = (png_byte)filter_type;
816 buf[12] = (png_byte)interlace_type;
818 /* Write the chunk */
819 png_write_complete_chunk(png_ptr, png_IHDR, buf, (png_size_t)13);
821 /* Initialize zlib with PNG info */
822 png_ptr->zstream.zalloc = png_zalloc;
823 png_ptr->zstream.zfree = png_zfree;
824 png_ptr->zstream.opaque = (voidpf)png_ptr;
826 if (!(png_ptr->do_filter))
828 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
829 png_ptr->bit_depth < 8)
830 png_ptr->do_filter = PNG_FILTER_NONE;
833 png_ptr->do_filter = PNG_ALL_FILTERS;
836 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY))
838 if (png_ptr->do_filter != PNG_FILTER_NONE)
839 png_ptr->zlib_strategy = Z_FILTERED;
842 png_ptr->zlib_strategy = Z_DEFAULT_STRATEGY;
845 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_LEVEL))
846 png_ptr->zlib_level = Z_DEFAULT_COMPRESSION;
848 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL))
849 png_ptr->zlib_mem_level = 8;
851 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS))
852 png_ptr->zlib_window_bits = 15;
854 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_METHOD))
855 png_ptr->zlib_method = 8;
857 #ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
858 #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
859 if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_STRATEGY))
860 png_ptr->zlib_text_strategy = Z_DEFAULT_STRATEGY;
862 if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_LEVEL))
863 png_ptr->zlib_text_level = png_ptr->zlib_level;
865 if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_MEM_LEVEL))
866 png_ptr->zlib_text_mem_level = png_ptr->zlib_mem_level;
868 if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_WINDOW_BITS))
869 png_ptr->zlib_text_window_bits = png_ptr->zlib_window_bits;
871 if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_METHOD))
872 png_ptr->zlib_text_method = png_ptr->zlib_method;
874 png_ptr->zlib_text_strategy = Z_DEFAULT_STRATEGY;
875 png_ptr->zlib_text_level = png_ptr->zlib_level;
876 png_ptr->zlib_text_mem_level = png_ptr->zlib_mem_level;
877 png_ptr->zlib_text_window_bits = png_ptr->zlib_window_bits;
878 png_ptr->zlib_text_method = png_ptr->zlib_method;
879 #endif /* PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED */
880 #endif /* PNG_WRITE_COMPRESSED_TEXT_SUPPORTED */
882 /* Record that the compressor has not yet been initialized. */
883 png_ptr->zlib_state = PNG_ZLIB_UNINITIALIZED;
885 png_ptr->mode = PNG_HAVE_IHDR; /* not READY_FOR_ZTXT */
888 /* Write the palette. We are careful not to trust png_color to be in the
889 * correct order for PNG, so people can redefine it to any convenient
893 png_write_PLTE(png_structp png_ptr, png_const_colorp palette,
897 png_const_colorp pal_ptr;
900 png_debug(1, "in png_write_PLTE");
903 #ifdef PNG_MNG_FEATURES_SUPPORTED
904 !(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) &&
906 num_pal == 0) || num_pal > 256)
908 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
910 png_error(png_ptr, "Invalid number of colors in palette");
915 png_warning(png_ptr, "Invalid number of colors in palette");
920 if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))
923 "Ignoring request to write a PLTE chunk in grayscale PNG");
928 png_ptr->num_palette = (png_uint_16)num_pal;
929 png_debug1(3, "num_palette = %d", png_ptr->num_palette);
931 png_write_chunk_header(png_ptr, png_PLTE, (png_uint_32)(num_pal * 3));
932 #ifdef PNG_POINTER_INDEXING_SUPPORTED
934 for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++)
936 buf[0] = pal_ptr->red;
937 buf[1] = pal_ptr->green;
938 buf[2] = pal_ptr->blue;
939 png_write_chunk_data(png_ptr, buf, (png_size_t)3);
943 /* This is a little slower but some buggy compilers need to do this
948 for (i = 0; i < num_pal; i++)
950 buf[0] = pal_ptr[i].red;
951 buf[1] = pal_ptr[i].green;
952 buf[2] = pal_ptr[i].blue;
953 png_write_chunk_data(png_ptr, buf, (png_size_t)3);
957 png_write_chunk_end(png_ptr);
958 png_ptr->mode |= PNG_HAVE_PLTE;
961 /* Write an IDAT chunk */
963 png_write_IDAT(png_structp png_ptr, png_bytep data, png_size_t length)
965 png_debug(1, "in png_write_IDAT");
967 #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
968 if (!(png_ptr->mode & PNG_HAVE_IDAT) &&
969 png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
971 /* Optimize the CMF field in the zlib stream. This hack of the zlib
972 * stream is compliant to the stream specification.
974 unsigned int z_cmf = data[0]; /* zlib compression method and flags */
976 if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
978 /* Avoid memory underflows and multiplication overflows.
980 * The conditions below are practically always satisfied;
981 * however, they still must be checked.
984 png_ptr->height < 16384 && png_ptr->width < 16384)
986 /* Compute the maximum possible length of the datastream */
988 /* Number of pixels, plus for each row a filter byte
989 * and possibly a padding byte, so increase the maximum
990 * size to account for these.
992 unsigned int z_cinfo;
993 unsigned int half_z_window_size;
994 png_uint_32 uncompressed_idat_size = png_ptr->height *
996 png_ptr->channels * png_ptr->bit_depth + 15) >> 3);
998 /* If it's interlaced, each block of 8 rows is sent as up to
999 * 14 rows, i.e., 6 additional rows, each with a filter byte
1000 * and possibly a padding byte
1002 if (png_ptr->interlaced)
1003 uncompressed_idat_size += ((png_ptr->height + 7)/8) *
1004 (png_ptr->bit_depth < 8 ? 12 : 6);
1006 z_cinfo = z_cmf >> 4;
1007 half_z_window_size = 1 << (z_cinfo + 7);
1009 while (uncompressed_idat_size <= half_z_window_size &&
1010 half_z_window_size >= 256)
1013 half_z_window_size >>= 1;
1016 z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
1018 if (data[0] != z_cmf)
1021 data[0] = (png_byte)z_cmf;
1022 tmp = data[1] & 0xe0;
1023 tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
1024 data[1] = (png_byte)tmp;
1031 "Invalid zlib compression method or flags in IDAT");
1033 #endif /* PNG_WRITE_OPTIMIZE_CMF_SUPPORTED */
1035 png_write_complete_chunk(png_ptr, png_IDAT, data, length);
1036 png_ptr->mode |= PNG_HAVE_IDAT;
1038 /* Prior to 1.5.4 this code was replicated in every caller (except at the
1039 * end, where it isn't technically necessary). Since this function has
1040 * flushed the data we can safely reset the zlib output buffer here.
1042 png_ptr->zstream.next_out = png_ptr->zbuf;
1043 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1046 /* Write an IEND chunk */
1048 png_write_IEND(png_structp png_ptr)
1050 png_debug(1, "in png_write_IEND");
1052 png_write_complete_chunk(png_ptr, png_IEND, NULL, (png_size_t)0);
1053 png_ptr->mode |= PNG_HAVE_IEND;
1056 #ifdef PNG_WRITE_gAMA_SUPPORTED
1057 /* Write a gAMA chunk */
1059 png_write_gAMA_fixed(png_structp png_ptr, png_fixed_point file_gamma)
1063 png_debug(1, "in png_write_gAMA");
1065 /* file_gamma is saved in 1/100,000ths */
1066 png_save_uint_32(buf, (png_uint_32)file_gamma);
1067 png_write_complete_chunk(png_ptr, png_gAMA, buf, (png_size_t)4);
1071 #ifdef PNG_WRITE_sRGB_SUPPORTED
1072 /* Write a sRGB chunk */
1074 png_write_sRGB(png_structp png_ptr, int srgb_intent)
1078 png_debug(1, "in png_write_sRGB");
1080 if (srgb_intent >= PNG_sRGB_INTENT_LAST)
1081 png_warning(png_ptr,
1082 "Invalid sRGB rendering intent specified");
1084 buf[0]=(png_byte)srgb_intent;
1085 png_write_complete_chunk(png_ptr, png_sRGB, buf, (png_size_t)1);
1089 #ifdef PNG_WRITE_iCCP_SUPPORTED
1090 /* Write an iCCP chunk */
1092 png_write_iCCP(png_structp png_ptr, png_const_charp name, int compression_type,
1093 png_const_charp profile, int profile_len)
1095 png_size_t name_len;
1097 compression_state comp;
1098 int embedded_profile_len = 0;
1100 png_debug(1, "in png_write_iCCP");
1102 comp.num_output_ptr = 0;
1103 comp.max_output_ptr = 0;
1104 comp.output_ptr = NULL;
1108 if ((name_len = png_check_keyword(png_ptr, name, &new_name)) == 0)
1111 if (compression_type != PNG_COMPRESSION_TYPE_BASE)
1112 png_warning(png_ptr, "Unknown compression type in iCCP chunk");
1114 if (profile == NULL)
1117 if (profile_len > 3)
1118 embedded_profile_len =
1119 ((*( (png_const_bytep)profile ))<<24) |
1120 ((*( (png_const_bytep)profile + 1))<<16) |
1121 ((*( (png_const_bytep)profile + 2))<< 8) |
1122 ((*( (png_const_bytep)profile + 3)) );
1124 if (embedded_profile_len < 0)
1126 png_warning(png_ptr,
1127 "Embedded profile length in iCCP chunk is negative");
1129 png_free(png_ptr, new_name);
1133 if (profile_len < embedded_profile_len)
1135 png_warning(png_ptr,
1136 "Embedded profile length too large in iCCP chunk");
1138 png_free(png_ptr, new_name);
1142 if (profile_len > embedded_profile_len)
1144 png_warning(png_ptr,
1145 "Truncating profile to actual length in iCCP chunk");
1147 profile_len = embedded_profile_len;
1151 profile_len = png_text_compress(png_ptr, profile,
1152 (png_size_t)profile_len, PNG_COMPRESSION_TYPE_BASE, &comp);
1154 /* Make sure we include the NULL after the name and the compression type */
1155 png_write_chunk_header(png_ptr, png_iCCP,
1156 (png_uint_32)(name_len + profile_len + 2));
1158 new_name[name_len + 1] = 0x00;
1160 png_write_chunk_data(png_ptr, (png_bytep)new_name,
1161 (png_size_t)(name_len + 2));
1165 png_write_compressed_data_out(png_ptr, &comp, profile_len);
1168 png_write_chunk_end(png_ptr);
1169 png_free(png_ptr, new_name);
1173 #ifdef PNG_WRITE_sPLT_SUPPORTED
1174 /* Write a sPLT chunk */
1176 png_write_sPLT(png_structp png_ptr, png_const_sPLT_tp spalette)
1178 png_size_t name_len;
1180 png_byte entrybuf[10];
1181 png_size_t entry_size = (spalette->depth == 8 ? 6 : 10);
1182 png_size_t palette_size = entry_size * spalette->nentries;
1184 #ifndef PNG_POINTER_INDEXING_SUPPORTED
1188 png_debug(1, "in png_write_sPLT");
1190 if ((name_len = png_check_keyword(png_ptr,spalette->name, &new_name))==0)
1193 /* Make sure we include the NULL after the name */
1194 png_write_chunk_header(png_ptr, png_sPLT,
1195 (png_uint_32)(name_len + 2 + palette_size));
1197 png_write_chunk_data(png_ptr, (png_bytep)new_name,
1198 (png_size_t)(name_len + 1));
1200 png_write_chunk_data(png_ptr, &spalette->depth, (png_size_t)1);
1202 /* Loop through each palette entry, writing appropriately */
1203 #ifdef PNG_POINTER_INDEXING_SUPPORTED
1204 for (ep = spalette->entries; ep<spalette->entries + spalette->nentries; ep++)
1206 if (spalette->depth == 8)
1208 entrybuf[0] = (png_byte)ep->red;
1209 entrybuf[1] = (png_byte)ep->green;
1210 entrybuf[2] = (png_byte)ep->blue;
1211 entrybuf[3] = (png_byte)ep->alpha;
1212 png_save_uint_16(entrybuf + 4, ep->frequency);
1217 png_save_uint_16(entrybuf + 0, ep->red);
1218 png_save_uint_16(entrybuf + 2, ep->green);
1219 png_save_uint_16(entrybuf + 4, ep->blue);
1220 png_save_uint_16(entrybuf + 6, ep->alpha);
1221 png_save_uint_16(entrybuf + 8, ep->frequency);
1224 png_write_chunk_data(png_ptr, entrybuf, (png_size_t)entry_size);
1227 ep=spalette->entries;
1228 for (i = 0; i>spalette->nentries; i++)
1230 if (spalette->depth == 8)
1232 entrybuf[0] = (png_byte)ep[i].red;
1233 entrybuf[1] = (png_byte)ep[i].green;
1234 entrybuf[2] = (png_byte)ep[i].blue;
1235 entrybuf[3] = (png_byte)ep[i].alpha;
1236 png_save_uint_16(entrybuf + 4, ep[i].frequency);
1241 png_save_uint_16(entrybuf + 0, ep[i].red);
1242 png_save_uint_16(entrybuf + 2, ep[i].green);
1243 png_save_uint_16(entrybuf + 4, ep[i].blue);
1244 png_save_uint_16(entrybuf + 6, ep[i].alpha);
1245 png_save_uint_16(entrybuf + 8, ep[i].frequency);
1248 png_write_chunk_data(png_ptr, entrybuf, (png_size_t)entry_size);
1252 png_write_chunk_end(png_ptr);
1253 png_free(png_ptr, new_name);
1257 #ifdef PNG_WRITE_sBIT_SUPPORTED
1258 /* Write the sBIT chunk */
1260 png_write_sBIT(png_structp png_ptr, png_const_color_8p sbit, int color_type)
1265 png_debug(1, "in png_write_sBIT");
1267 /* Make sure we don't depend upon the order of PNG_COLOR_8 */
1268 if (color_type & PNG_COLOR_MASK_COLOR)
1272 maxbits = (png_byte)(color_type==PNG_COLOR_TYPE_PALETTE ? 8 :
1273 png_ptr->usr_bit_depth);
1275 if (sbit->red == 0 || sbit->red > maxbits ||
1276 sbit->green == 0 || sbit->green > maxbits ||
1277 sbit->blue == 0 || sbit->blue > maxbits)
1279 png_warning(png_ptr, "Invalid sBIT depth specified");
1284 buf[1] = sbit->green;
1285 buf[2] = sbit->blue;
1291 if (sbit->gray == 0 || sbit->gray > png_ptr->usr_bit_depth)
1293 png_warning(png_ptr, "Invalid sBIT depth specified");
1297 buf[0] = sbit->gray;
1301 if (color_type & PNG_COLOR_MASK_ALPHA)
1303 if (sbit->alpha == 0 || sbit->alpha > png_ptr->usr_bit_depth)
1305 png_warning(png_ptr, "Invalid sBIT depth specified");
1309 buf[size++] = sbit->alpha;
1312 png_write_complete_chunk(png_ptr, png_sBIT, buf, size);
1316 #ifdef PNG_WRITE_cHRM_SUPPORTED
1317 /* Write the cHRM chunk */
1319 png_write_cHRM_fixed(png_structp png_ptr, png_fixed_point white_x,
1320 png_fixed_point white_y, png_fixed_point red_x, png_fixed_point red_y,
1321 png_fixed_point green_x, png_fixed_point green_y, png_fixed_point blue_x,
1322 png_fixed_point blue_y)
1326 png_debug(1, "in png_write_cHRM");
1328 /* Each value is saved in 1/100,000ths */
1329 #ifdef PNG_CHECK_cHRM_SUPPORTED
1330 if (png_check_cHRM_fixed(png_ptr, white_x, white_y, red_x, red_y,
1331 green_x, green_y, blue_x, blue_y))
1334 png_save_uint_32(buf, (png_uint_32)white_x);
1335 png_save_uint_32(buf + 4, (png_uint_32)white_y);
1337 png_save_uint_32(buf + 8, (png_uint_32)red_x);
1338 png_save_uint_32(buf + 12, (png_uint_32)red_y);
1340 png_save_uint_32(buf + 16, (png_uint_32)green_x);
1341 png_save_uint_32(buf + 20, (png_uint_32)green_y);
1343 png_save_uint_32(buf + 24, (png_uint_32)blue_x);
1344 png_save_uint_32(buf + 28, (png_uint_32)blue_y);
1346 png_write_complete_chunk(png_ptr, png_cHRM, buf, (png_size_t)32);
1351 #ifdef PNG_WRITE_tRNS_SUPPORTED
1352 /* Write the tRNS chunk */
1354 png_write_tRNS(png_structp png_ptr, png_const_bytep trans_alpha,
1355 png_const_color_16p tran, int num_trans, int color_type)
1359 png_debug(1, "in png_write_tRNS");
1361 if (color_type == PNG_COLOR_TYPE_PALETTE)
1363 if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette)
1365 png_warning(png_ptr, "Invalid number of transparent colors specified");
1369 /* Write the chunk out as it is */
1370 png_write_complete_chunk(png_ptr, png_tRNS, trans_alpha,
1371 (png_size_t)num_trans);
1374 else if (color_type == PNG_COLOR_TYPE_GRAY)
1376 /* One 16 bit value */
1377 if (tran->gray >= (1 << png_ptr->bit_depth))
1379 png_warning(png_ptr,
1380 "Ignoring attempt to write tRNS chunk out-of-range for bit_depth");
1385 png_save_uint_16(buf, tran->gray);
1386 png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)2);
1389 else if (color_type == PNG_COLOR_TYPE_RGB)
1391 /* Three 16 bit values */
1392 png_save_uint_16(buf, tran->red);
1393 png_save_uint_16(buf + 2, tran->green);
1394 png_save_uint_16(buf + 4, tran->blue);
1395 #ifdef PNG_WRITE_16BIT_SUPPORTED
1396 if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))
1398 if (buf[0] | buf[2] | buf[4])
1401 png_warning(png_ptr,
1402 "Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8");
1406 png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)6);
1411 png_warning(png_ptr, "Can't write tRNS with an alpha channel");
1416 #ifdef PNG_WRITE_bKGD_SUPPORTED
1417 /* Write the background chunk */
1419 png_write_bKGD(png_structp png_ptr, png_const_color_16p back, int color_type)
1423 png_debug(1, "in png_write_bKGD");
1425 if (color_type == PNG_COLOR_TYPE_PALETTE)
1428 #ifdef PNG_MNG_FEATURES_SUPPORTED
1429 (png_ptr->num_palette ||
1430 (!(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE))) &&
1432 back->index >= png_ptr->num_palette)
1434 png_warning(png_ptr, "Invalid background palette index");
1438 buf[0] = back->index;
1439 png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)1);
1442 else if (color_type & PNG_COLOR_MASK_COLOR)
1444 png_save_uint_16(buf, back->red);
1445 png_save_uint_16(buf + 2, back->green);
1446 png_save_uint_16(buf + 4, back->blue);
1447 #ifdef PNG_WRITE_16BIT_SUPPORTED
1448 if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))
1450 if (buf[0] | buf[2] | buf[4])
1453 png_warning(png_ptr,
1454 "Ignoring attempt to write 16-bit bKGD chunk when bit_depth is 8");
1459 png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)6);
1464 if (back->gray >= (1 << png_ptr->bit_depth))
1466 png_warning(png_ptr,
1467 "Ignoring attempt to write bKGD chunk out-of-range for bit_depth");
1472 png_save_uint_16(buf, back->gray);
1473 png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)2);
1478 #ifdef PNG_WRITE_hIST_SUPPORTED
1479 /* Write the histogram */
1481 png_write_hIST(png_structp png_ptr, png_const_uint_16p hist, int num_hist)
1486 png_debug(1, "in png_write_hIST");
1488 if (num_hist > (int)png_ptr->num_palette)
1490 png_debug2(3, "num_hist = %d, num_palette = %d", num_hist,
1491 png_ptr->num_palette);
1493 png_warning(png_ptr, "Invalid number of histogram entries specified");
1497 png_write_chunk_header(png_ptr, png_hIST, (png_uint_32)(num_hist * 2));
1499 for (i = 0; i < num_hist; i++)
1501 png_save_uint_16(buf, hist[i]);
1502 png_write_chunk_data(png_ptr, buf, (png_size_t)2);
1505 png_write_chunk_end(png_ptr);
1509 #if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \
1510 defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
1511 /* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification,
1512 * and if invalid, correct the keyword rather than discarding the entire
1513 * chunk. The PNG 1.0 specification requires keywords 1-79 characters in
1514 * length, forbids leading or trailing whitespace, multiple internal spaces,
1515 * and the non-break space (0x80) from ISO 8859-1. Returns keyword length.
1517 * The new_key is allocated to hold the corrected keyword and must be freed
1518 * by the calling routine. This avoids problems with trying to write to
1519 * static keywords without having to have duplicate copies of the strings.
1521 png_size_t /* PRIVATE */
1522 png_check_keyword(png_structp png_ptr, png_const_charp key, png_charpp new_key)
1525 png_const_charp ikp;
1530 png_debug(1, "in png_check_keyword");
1534 if (key == NULL || (key_len = png_strlen(key)) == 0)
1536 png_warning(png_ptr, "zero length keyword");
1537 return ((png_size_t)0);
1540 png_debug1(2, "Keyword to be checked is '%s'", key);
1542 *new_key = (png_charp)png_malloc_warn(png_ptr, (png_uint_32)(key_len + 2));
1544 if (*new_key == NULL)
1546 png_warning(png_ptr, "Out of memory while procesing keyword");
1547 return ((png_size_t)0);
1550 /* Replace non-printing characters with a blank and print a warning */
1551 for (ikp = key, dp = *new_key; *ikp != '\0'; ikp++, dp++)
1553 if ((png_byte)*ikp < 0x20 ||
1554 ((png_byte)*ikp > 0x7E && (png_byte)*ikp < 0xA1))
1556 PNG_WARNING_PARAMETERS(p)
1558 png_warning_parameter_unsigned(p, 1, PNG_NUMBER_FORMAT_02x,
1560 png_formatted_warning(png_ptr, p, "invalid keyword character 0x@1");
1571 /* Remove any trailing white space. */
1572 kp = *new_key + key_len - 1;
1575 png_warning(png_ptr, "trailing spaces removed from keyword");
1584 /* Remove any leading white space. */
1588 png_warning(png_ptr, "leading spaces removed from keyword");
1597 png_debug1(2, "Checking for multiple internal spaces in '%s'", kp);
1599 /* Remove multiple internal spaces. */
1600 for (kflag = 0, dp = *new_key; *kp != '\0'; kp++)
1602 if (*kp == ' ' && kflag == 0)
1608 else if (*kp == ' ')
1622 png_warning(png_ptr, "extra interior spaces removed from keyword");
1626 png_free(png_ptr, *new_key);
1627 png_warning(png_ptr, "Zero length keyword");
1632 png_warning(png_ptr, "keyword length must be 1 - 79 characters");
1633 (*new_key)[79] = '\0';
1641 #ifdef PNG_WRITE_tEXt_SUPPORTED
1642 /* Write a tEXt chunk */
1644 png_write_tEXt(png_structp png_ptr, png_const_charp key, png_const_charp text,
1645 png_size_t text_len)
1650 png_debug(1, "in png_write_tEXt");
1652 if ((key_len = png_check_keyword(png_ptr, key, &new_key))==0)
1655 if (text == NULL || *text == '\0')
1659 text_len = png_strlen(text);
1661 /* Make sure we include the 0 after the key */
1662 png_write_chunk_header(png_ptr, png_tEXt,
1663 (png_uint_32)(key_len + text_len + 1));
1665 * We leave it to the application to meet PNG-1.0 requirements on the
1666 * contents of the text. PNG-1.0 through PNG-1.2 discourage the use of
1667 * any non-Latin-1 characters except for NEWLINE. ISO PNG will forbid them.
1668 * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1670 png_write_chunk_data(png_ptr, (png_bytep)new_key,
1671 (png_size_t)(key_len + 1));
1674 png_write_chunk_data(png_ptr, (png_const_bytep)text,
1675 (png_size_t)text_len);
1677 png_write_chunk_end(png_ptr);
1678 png_free(png_ptr, new_key);
1682 #ifdef PNG_WRITE_zTXt_SUPPORTED
1683 /* Write a compressed text chunk */
1685 png_write_zTXt(png_structp png_ptr, png_const_charp key, png_const_charp text,
1686 png_size_t text_len, int compression)
1691 compression_state comp;
1693 png_debug(1, "in png_write_zTXt");
1695 comp.num_output_ptr = 0;
1696 comp.max_output_ptr = 0;
1697 comp.output_ptr = NULL;
1701 if ((key_len = png_check_keyword(png_ptr, key, &new_key)) == 0)
1703 png_free(png_ptr, new_key);
1707 if (text == NULL || *text == '\0' || compression==PNG_TEXT_COMPRESSION_NONE)
1709 png_write_tEXt(png_ptr, new_key, text, (png_size_t)0);
1710 png_free(png_ptr, new_key);
1714 text_len = png_strlen(text);
1716 /* Compute the compressed data; do it now for the length */
1717 text_len = png_text_compress(png_ptr, text, text_len, compression,
1720 /* Write start of chunk */
1721 png_write_chunk_header(png_ptr, png_zTXt,
1722 (png_uint_32)(key_len+text_len + 2));
1725 png_write_chunk_data(png_ptr, (png_bytep)new_key,
1726 (png_size_t)(key_len + 1));
1728 png_free(png_ptr, new_key);
1730 buf = (png_byte)compression;
1732 /* Write compression */
1733 png_write_chunk_data(png_ptr, &buf, (png_size_t)1);
1735 /* Write the compressed data */
1736 png_write_compressed_data_out(png_ptr, &comp, text_len);
1738 /* Close the chunk */
1739 png_write_chunk_end(png_ptr);
1743 #ifdef PNG_WRITE_iTXt_SUPPORTED
1744 /* Write an iTXt chunk */
1746 png_write_iTXt(png_structp png_ptr, int compression, png_const_charp key,
1747 png_const_charp lang, png_const_charp lang_key, png_const_charp text)
1749 png_size_t lang_len, key_len, lang_key_len, text_len;
1751 png_charp new_key = NULL;
1753 compression_state comp;
1755 png_debug(1, "in png_write_iTXt");
1757 comp.num_output_ptr = 0;
1758 comp.max_output_ptr = 0;
1759 comp.output_ptr = NULL;
1762 if ((key_len = png_check_keyword(png_ptr, key, &new_key)) == 0)
1765 if ((lang_len = png_check_keyword(png_ptr, lang, &new_lang)) == 0)
1767 png_warning(png_ptr, "Empty language field in iTXt chunk");
1772 if (lang_key == NULL)
1776 lang_key_len = png_strlen(lang_key);
1782 text_len = png_strlen(text);
1784 /* Compute the compressed data; do it now for the length */
1785 text_len = png_text_compress(png_ptr, text, text_len, compression - 2,
1789 /* Make sure we include the compression flag, the compression byte,
1790 * and the NULs after the key, lang, and lang_key parts
1793 png_write_chunk_header(png_ptr, png_iTXt, (png_uint_32)(
1794 5 /* comp byte, comp flag, terminators for key, lang and lang_key */
1800 /* We leave it to the application to meet PNG-1.0 requirements on the
1801 * contents of the text. PNG-1.0 through PNG-1.2 discourage the use of
1802 * any non-Latin-1 characters except for NEWLINE. ISO PNG will forbid them.
1803 * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1805 png_write_chunk_data(png_ptr, (png_bytep)new_key, (png_size_t)(key_len + 1));
1807 /* Set the compression flag */
1808 if (compression == PNG_ITXT_COMPRESSION_NONE ||
1809 compression == PNG_TEXT_COMPRESSION_NONE)
1812 else /* compression == PNG_ITXT_COMPRESSION_zTXt */
1815 /* Set the compression method */
1818 png_write_chunk_data(png_ptr, cbuf, (png_size_t)2);
1821 png_write_chunk_data(png_ptr, (new_lang ? (png_const_bytep)new_lang : cbuf),
1822 (png_size_t)(lang_len + 1));
1824 png_write_chunk_data(png_ptr, (lang_key ? (png_const_bytep)lang_key : cbuf),
1825 (png_size_t)(lang_key_len + 1));
1827 png_write_compressed_data_out(png_ptr, &comp, text_len);
1829 png_write_chunk_end(png_ptr);
1831 png_free(png_ptr, new_key);
1832 png_free(png_ptr, new_lang);
1836 #ifdef PNG_WRITE_oFFs_SUPPORTED
1837 /* Write the oFFs chunk */
1839 png_write_oFFs(png_structp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
1844 png_debug(1, "in png_write_oFFs");
1846 if (unit_type >= PNG_OFFSET_LAST)
1847 png_warning(png_ptr, "Unrecognized unit type for oFFs chunk");
1849 png_save_int_32(buf, x_offset);
1850 png_save_int_32(buf + 4, y_offset);
1851 buf[8] = (png_byte)unit_type;
1853 png_write_complete_chunk(png_ptr, png_oFFs, buf, (png_size_t)9);
1856 #ifdef PNG_WRITE_pCAL_SUPPORTED
1857 /* Write the pCAL chunk (described in the PNG extensions document) */
1859 png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
1860 png_int_32 X1, int type, int nparams, png_const_charp units,
1863 png_size_t purpose_len, units_len, total_len;
1864 png_size_tp params_len;
1866 png_charp new_purpose;
1869 png_debug1(1, "in png_write_pCAL (%d parameters)", nparams);
1871 if (type >= PNG_EQUATION_LAST)
1872 png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");
1874 purpose_len = png_check_keyword(png_ptr, purpose, &new_purpose) + 1;
1875 png_debug1(3, "pCAL purpose length = %d", (int)purpose_len);
1876 units_len = png_strlen(units) + (nparams == 0 ? 0 : 1);
1877 png_debug1(3, "pCAL units length = %d", (int)units_len);
1878 total_len = purpose_len + units_len + 10;
1880 params_len = (png_size_tp)png_malloc(png_ptr,
1881 (png_alloc_size_t)(nparams * png_sizeof(png_size_t)));
1883 /* Find the length of each parameter, making sure we don't count the
1884 * null terminator for the last parameter.
1886 for (i = 0; i < nparams; i++)
1888 params_len[i] = png_strlen(params[i]) + (i == nparams - 1 ? 0 : 1);
1889 png_debug2(3, "pCAL parameter %d length = %lu", i,
1890 (unsigned long)params_len[i]);
1891 total_len += params_len[i];
1894 png_debug1(3, "pCAL total length = %d", (int)total_len);
1895 png_write_chunk_header(png_ptr, png_pCAL, (png_uint_32)total_len);
1896 png_write_chunk_data(png_ptr, (png_const_bytep)new_purpose, purpose_len);
1897 png_save_int_32(buf, X0);
1898 png_save_int_32(buf + 4, X1);
1899 buf[8] = (png_byte)type;
1900 buf[9] = (png_byte)nparams;
1901 png_write_chunk_data(png_ptr, buf, (png_size_t)10);
1902 png_write_chunk_data(png_ptr, (png_const_bytep)units, (png_size_t)units_len);
1904 png_free(png_ptr, new_purpose);
1906 for (i = 0; i < nparams; i++)
1908 png_write_chunk_data(png_ptr, (png_const_bytep)params[i], params_len[i]);
1911 png_free(png_ptr, params_len);
1912 png_write_chunk_end(png_ptr);
1916 #ifdef PNG_WRITE_sCAL_SUPPORTED
1917 /* Write the sCAL chunk */
1919 png_write_sCAL_s(png_structp png_ptr, int unit, png_const_charp width,
1920 png_const_charp height)
1923 png_size_t wlen, hlen, total_len;
1925 png_debug(1, "in png_write_sCAL_s");
1927 wlen = png_strlen(width);
1928 hlen = png_strlen(height);
1929 total_len = wlen + hlen + 2;
1933 png_warning(png_ptr, "Can't write sCAL (buffer too small)");
1937 buf[0] = (png_byte)unit;
1938 png_memcpy(buf + 1, width, wlen + 1); /* Append the '\0' here */
1939 png_memcpy(buf + wlen + 2, height, hlen); /* Do NOT append the '\0' here */
1941 png_debug1(3, "sCAL total length = %u", (unsigned int)total_len);
1942 png_write_complete_chunk(png_ptr, png_sCAL, buf, total_len);
1946 #ifdef PNG_WRITE_pHYs_SUPPORTED
1947 /* Write the pHYs chunk */
1949 png_write_pHYs(png_structp png_ptr, png_uint_32 x_pixels_per_unit,
1950 png_uint_32 y_pixels_per_unit,
1955 png_debug(1, "in png_write_pHYs");
1957 if (unit_type >= PNG_RESOLUTION_LAST)
1958 png_warning(png_ptr, "Unrecognized unit type for pHYs chunk");
1960 png_save_uint_32(buf, x_pixels_per_unit);
1961 png_save_uint_32(buf + 4, y_pixels_per_unit);
1962 buf[8] = (png_byte)unit_type;
1964 png_write_complete_chunk(png_ptr, png_pHYs, buf, (png_size_t)9);
1968 #ifdef PNG_WRITE_tIME_SUPPORTED
1969 /* Write the tIME chunk. Use either png_convert_from_struct_tm()
1970 * or png_convert_from_time_t(), or fill in the structure yourself.
1973 png_write_tIME(png_structp png_ptr, png_const_timep mod_time)
1977 png_debug(1, "in png_write_tIME");
1979 if (mod_time->month > 12 || mod_time->month < 1 ||
1980 mod_time->day > 31 || mod_time->day < 1 ||
1981 mod_time->hour > 23 || mod_time->second > 60)
1983 png_warning(png_ptr, "Invalid time specified for tIME chunk");
1987 png_save_uint_16(buf, mod_time->year);
1988 buf[2] = mod_time->month;
1989 buf[3] = mod_time->day;
1990 buf[4] = mod_time->hour;
1991 buf[5] = mod_time->minute;
1992 buf[6] = mod_time->second;
1994 png_write_complete_chunk(png_ptr, png_tIME, buf, (png_size_t)7);
1998 /* Initializes the row writing capability of libpng */
2000 png_write_start_row(png_structp png_ptr)
2002 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
2003 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
2005 /* Start of interlace block */
2006 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
2008 /* Offset to next interlace block */
2009 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
2011 /* Start of interlace block in the y direction */
2012 static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
2014 /* Offset to next interlace block in the y direction */
2015 static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
2018 png_alloc_size_t buf_size;
2019 int usr_pixel_depth;
2021 png_debug(1, "in png_write_start_row");
2023 usr_pixel_depth = png_ptr->usr_channels * png_ptr->usr_bit_depth;
2024 buf_size = PNG_ROWBYTES(usr_pixel_depth, png_ptr->width) + 1;
2026 /* 1.5.6: added to allow checking in the row write code. */
2027 png_ptr->transformed_pixel_depth = png_ptr->pixel_depth;
2028 png_ptr->maximum_pixel_depth = (png_byte)usr_pixel_depth;
2030 /* Set up row buffer */
2031 png_ptr->row_buf = (png_bytep)png_malloc(png_ptr, buf_size);
2033 png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE;
2035 #ifdef PNG_WRITE_FILTER_SUPPORTED
2036 /* Set up filtering buffer, if using this filter */
2037 if (png_ptr->do_filter & PNG_FILTER_SUB)
2039 png_ptr->sub_row = (png_bytep)png_malloc(png_ptr, png_ptr->rowbytes + 1);
2041 png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
2044 /* We only need to keep the previous row if we are using one of these. */
2045 if (png_ptr->do_filter & (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH))
2047 /* Set up previous row buffer */
2048 png_ptr->prev_row = (png_bytep)png_calloc(png_ptr, buf_size);
2050 if (png_ptr->do_filter & PNG_FILTER_UP)
2052 png_ptr->up_row = (png_bytep)png_malloc(png_ptr,
2053 png_ptr->rowbytes + 1);
2055 png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;
2058 if (png_ptr->do_filter & PNG_FILTER_AVG)
2060 png_ptr->avg_row = (png_bytep)png_malloc(png_ptr,
2061 png_ptr->rowbytes + 1);
2063 png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;
2066 if (png_ptr->do_filter & PNG_FILTER_PAETH)
2068 png_ptr->paeth_row = (png_bytep)png_malloc(png_ptr,
2069 png_ptr->rowbytes + 1);
2071 png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
2074 #endif /* PNG_WRITE_FILTER_SUPPORTED */
2076 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
2077 /* If interlaced, we need to set up width and height of pass */
2078 if (png_ptr->interlaced)
2080 if (!(png_ptr->transformations & PNG_INTERLACE))
2082 png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
2083 png_pass_ystart[0]) / png_pass_yinc[0];
2085 png_ptr->usr_width = (png_ptr->width + png_pass_inc[0] - 1 -
2086 png_pass_start[0]) / png_pass_inc[0];
2091 png_ptr->num_rows = png_ptr->height;
2092 png_ptr->usr_width = png_ptr->width;
2099 png_ptr->num_rows = png_ptr->height;
2100 png_ptr->usr_width = png_ptr->width;
2103 png_zlib_claim(png_ptr, PNG_ZLIB_FOR_IDAT);
2104 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
2105 png_ptr->zstream.next_out = png_ptr->zbuf;
2108 /* Internal use only. Called when finished processing a row of data. */
2110 png_write_finish_row(png_structp png_ptr)
2112 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
2113 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
2115 /* Start of interlace block */
2116 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
2118 /* Offset to next interlace block */
2119 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
2121 /* Start of interlace block in the y direction */
2122 static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
2124 /* Offset to next interlace block in the y direction */
2125 static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
2130 png_debug(1, "in png_write_finish_row");
2133 png_ptr->row_number++;
2135 /* See if we are done */
2136 if (png_ptr->row_number < png_ptr->num_rows)
2139 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
2140 /* If interlaced, go to next pass */
2141 if (png_ptr->interlaced)
2143 png_ptr->row_number = 0;
2144 if (png_ptr->transformations & PNG_INTERLACE)
2151 /* Loop until we find a non-zero width or height pass */
2156 if (png_ptr->pass >= 7)
2159 png_ptr->usr_width = (png_ptr->width +
2160 png_pass_inc[png_ptr->pass] - 1 -
2161 png_pass_start[png_ptr->pass]) /
2162 png_pass_inc[png_ptr->pass];
2164 png_ptr->num_rows = (png_ptr->height +
2165 png_pass_yinc[png_ptr->pass] - 1 -
2166 png_pass_ystart[png_ptr->pass]) /
2167 png_pass_yinc[png_ptr->pass];
2169 if (png_ptr->transformations & PNG_INTERLACE)
2172 } while (png_ptr->usr_width == 0 || png_ptr->num_rows == 0);
2176 /* Reset the row above the image for the next pass */
2177 if (png_ptr->pass < 7)
2179 if (png_ptr->prev_row != NULL)
2180 png_memset(png_ptr->prev_row, 0,
2181 (png_size_t)(PNG_ROWBYTES(png_ptr->usr_channels*
2182 png_ptr->usr_bit_depth, png_ptr->width)) + 1);
2189 /* If we get here, we've just written the last row, so we need
2190 to flush the compressor */
2193 /* Tell the compressor we are done */
2194 ret = deflate(&png_ptr->zstream, Z_FINISH);
2196 /* Check for an error */
2199 /* Check to see if we need more room */
2200 if (!(png_ptr->zstream.avail_out))
2202 png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
2203 png_ptr->zstream.next_out = png_ptr->zbuf;
2204 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
2208 else if (ret != Z_STREAM_END)
2210 if (png_ptr->zstream.msg != NULL)
2211 png_error(png_ptr, png_ptr->zstream.msg);
2214 png_error(png_ptr, "zlib error");
2216 } while (ret != Z_STREAM_END);
2218 /* Write any extra space */
2219 if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
2221 png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size -
2222 png_ptr->zstream.avail_out);
2225 png_zlib_release(png_ptr);
2226 png_ptr->zstream.data_type = Z_BINARY;
2229 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
2230 /* Pick out the correct pixels for the interlace pass.
2231 * The basic idea here is to go through the row with a source
2232 * pointer and a destination pointer (sp and dp), and copy the
2233 * correct pixels for the pass. As the row gets compacted,
2234 * sp will always be >= dp, so we should never overwrite anything.
2235 * See the default: case for the easiest code to understand.
2238 png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
2240 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
2242 /* Start of interlace block */
2243 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
2245 /* Offset to next interlace block */
2246 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
2248 png_debug(1, "in png_do_write_interlace");
2250 /* We don't have to do anything on the last pass (6) */
2253 /* Each pixel depth is handled separately */
2254 switch (row_info->pixel_depth)
2264 png_uint_32 row_width = row_info->width;
2270 for (i = png_pass_start[pass]; i < row_width;
2271 i += png_pass_inc[pass])
2273 sp = row + (png_size_t)(i >> 3);
2274 value = (int)(*sp >> (7 - (int)(i & 0x07))) & 0x01;
2275 d |= (value << shift);
2280 *dp++ = (png_byte)d;
2302 png_uint_32 row_width = row_info->width;
2308 for (i = png_pass_start[pass]; i < row_width;
2309 i += png_pass_inc[pass])
2311 sp = row + (png_size_t)(i >> 2);
2312 value = (*sp >> ((3 - (int)(i & 0x03)) << 1)) & 0x03;
2313 d |= (value << shift);
2318 *dp++ = (png_byte)d;
2339 png_uint_32 row_width = row_info->width;
2344 for (i = png_pass_start[pass]; i < row_width;
2345 i += png_pass_inc[pass])
2347 sp = row + (png_size_t)(i >> 1);
2348 value = (*sp >> ((1 - (int)(i & 0x01)) << 2)) & 0x0f;
2349 d |= (value << shift);
2354 *dp++ = (png_byte)d;
2372 png_uint_32 row_width = row_info->width;
2373 png_size_t pixel_bytes;
2375 /* Start at the beginning */
2378 /* Find out how many bytes each pixel takes up */
2379 pixel_bytes = (row_info->pixel_depth >> 3);
2381 /* Loop through the row, only looking at the pixels that matter */
2382 for (i = png_pass_start[pass]; i < row_width;
2383 i += png_pass_inc[pass])
2385 /* Find out where the original pixel is */
2386 sp = row + (png_size_t)i * pixel_bytes;
2388 /* Move the pixel */
2390 png_memcpy(dp, sp, pixel_bytes);
2398 /* Set new row width */
2399 row_info->width = (row_info->width +
2400 png_pass_inc[pass] - 1 -
2401 png_pass_start[pass]) /
2404 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
2410 /* This filters the row, chooses which filter to use, if it has not already
2411 * been specified by the application, and then writes the row out with the
2414 static void png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row,
2415 png_size_t row_bytes);
2417 #define PNG_MAXSUM (((png_uint_32)(-1)) >> 1)
2418 #define PNG_HISHIFT 10
2419 #define PNG_LOMASK ((png_uint_32)0xffffL)
2420 #define PNG_HIMASK ((png_uint_32)(~PNG_LOMASK >> PNG_HISHIFT))
2422 png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
2425 #ifdef PNG_WRITE_FILTER_SUPPORTED
2426 png_bytep prev_row, row_buf;
2427 png_uint_32 mins, bpp;
2428 png_byte filter_to_do = png_ptr->do_filter;
2429 png_size_t row_bytes = row_info->rowbytes;
2430 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2431 int num_p_filters = png_ptr->num_prev_filters;
2434 png_debug(1, "in png_write_find_filter");
2436 #ifndef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2437 if (png_ptr->row_number == 0 && filter_to_do == PNG_ALL_FILTERS)
2439 /* These will never be selected so we need not test them. */
2440 filter_to_do &= ~(PNG_FILTER_UP | PNG_FILTER_PAETH);
2444 /* Find out how many bytes offset each pixel is */
2445 bpp = (row_info->pixel_depth + 7) >> 3;
2447 prev_row = png_ptr->prev_row;
2449 best_row = png_ptr->row_buf;
2450 #ifdef PNG_WRITE_FILTER_SUPPORTED
2454 /* The prediction method we use is to find which method provides the
2455 * smallest value when summing the absolute values of the distances
2456 * from zero, using anything >= 128 as negative numbers. This is known
2457 * as the "minimum sum of absolute differences" heuristic. Other
2458 * heuristics are the "weighted minimum sum of absolute differences"
2459 * (experimental and can in theory improve compression), and the "zlib
2460 * predictive" method (not implemented yet), which does test compressions
2461 * of lines using different filter methods, and then chooses the
2462 * (series of) filter(s) that give minimum compressed data size (VERY
2463 * computationally expensive).
2465 * GRR 980525: consider also
2467 * (1) minimum sum of absolute differences from running average (i.e.,
2468 * keep running sum of non-absolute differences & count of bytes)
2469 * [track dispersion, too? restart average if dispersion too large?]
2471 * (1b) minimum sum of absolute differences from sliding average, probably
2472 * with window size <= deflate window (usually 32K)
2474 * (2) minimum sum of squared differences from zero or running average
2475 * (i.e., ~ root-mean-square approach)
2479 /* We don't need to test the 'no filter' case if this is the only filter
2480 * that has been chosen, as it doesn't actually do anything to the data.
2482 if ((filter_to_do & PNG_FILTER_NONE) && filter_to_do != PNG_FILTER_NONE)
2485 png_uint_32 sum = 0;
2489 for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
2492 sum += (v < 128) ? v : 256 - v;
2495 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2496 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2498 png_uint_32 sumhi, sumlo;
2500 sumlo = sum & PNG_LOMASK;
2501 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; /* Gives us some footroom */
2503 /* Reduce the sum if we match any of the previous rows */
2504 for (j = 0; j < num_p_filters; j++)
2506 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
2508 sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2511 sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2516 /* Factor in the cost of this filter (this is here for completeness,
2517 * but it makes no sense to have a "cost" for the NONE filter, as
2518 * it has the minimum possible computational cost - none).
2520 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
2523 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
2526 if (sumhi > PNG_HIMASK)
2530 sum = (sumhi << PNG_HISHIFT) + sumlo;
2537 if (filter_to_do == PNG_FILTER_SUB)
2538 /* It's the only filter so no testing is needed */
2540 png_bytep rp, lp, dp;
2543 for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
2549 for (lp = row_buf + 1; i < row_bytes;
2550 i++, rp++, lp++, dp++)
2552 *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
2555 best_row = png_ptr->sub_row;
2558 else if (filter_to_do & PNG_FILTER_SUB)
2560 png_bytep rp, dp, lp;
2561 png_uint_32 sum = 0, lmins = mins;
2565 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2566 /* We temporarily increase the "minimum sum" by the factor we
2567 * would reduce the sum of this filter, so that we can do the
2568 * early exit comparison without scaling the sum each time.
2570 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2573 png_uint_32 lmhi, lmlo;
2574 lmlo = lmins & PNG_LOMASK;
2575 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2577 for (j = 0; j < num_p_filters; j++)
2579 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
2581 lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2584 lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2589 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2592 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2595 if (lmhi > PNG_HIMASK)
2599 lmins = (lmhi << PNG_HISHIFT) + lmlo;
2603 for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
2608 sum += (v < 128) ? v : 256 - v;
2611 for (lp = row_buf + 1; i < row_bytes;
2612 i++, rp++, lp++, dp++)
2614 v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
2616 sum += (v < 128) ? v : 256 - v;
2618 if (sum > lmins) /* We are already worse, don't continue. */
2622 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2623 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2626 png_uint_32 sumhi, sumlo;
2627 sumlo = sum & PNG_LOMASK;
2628 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2630 for (j = 0; j < num_p_filters; j++)
2632 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
2634 sumlo = (sumlo * png_ptr->inv_filter_weights[j]) >>
2637 sumhi = (sumhi * png_ptr->inv_filter_weights[j]) >>
2642 sumlo = (sumlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2645 sumhi = (sumhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2648 if (sumhi > PNG_HIMASK)
2652 sum = (sumhi << PNG_HISHIFT) + sumlo;
2659 best_row = png_ptr->sub_row;
2664 if (filter_to_do == PNG_FILTER_UP)
2666 png_bytep rp, dp, pp;
2669 for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
2670 pp = prev_row + 1; i < row_bytes;
2671 i++, rp++, pp++, dp++)
2673 *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
2676 best_row = png_ptr->up_row;
2679 else if (filter_to_do & PNG_FILTER_UP)
2681 png_bytep rp, dp, pp;
2682 png_uint_32 sum = 0, lmins = mins;
2687 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2688 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2691 png_uint_32 lmhi, lmlo;
2692 lmlo = lmins & PNG_LOMASK;
2693 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2695 for (j = 0; j < num_p_filters; j++)
2697 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
2699 lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2702 lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2707 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
2710 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
2713 if (lmhi > PNG_HIMASK)
2717 lmins = (lmhi << PNG_HISHIFT) + lmlo;
2721 for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
2722 pp = prev_row + 1; i < row_bytes; i++)
2724 v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2726 sum += (v < 128) ? v : 256 - v;
2728 if (sum > lmins) /* We are already worse, don't continue. */
2732 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2733 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2736 png_uint_32 sumhi, sumlo;
2737 sumlo = sum & PNG_LOMASK;
2738 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2740 for (j = 0; j < num_p_filters; j++)
2742 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
2744 sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2747 sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2752 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
2755 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
2758 if (sumhi > PNG_HIMASK)
2762 sum = (sumhi << PNG_HISHIFT) + sumlo;
2769 best_row = png_ptr->up_row;
2774 if (filter_to_do == PNG_FILTER_AVG)
2776 png_bytep rp, dp, pp, lp;
2779 for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
2780 pp = prev_row + 1; i < bpp; i++)
2782 *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
2785 for (lp = row_buf + 1; i < row_bytes; i++)
2787 *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
2790 best_row = png_ptr->avg_row;
2793 else if (filter_to_do & PNG_FILTER_AVG)
2795 png_bytep rp, dp, pp, lp;
2796 png_uint_32 sum = 0, lmins = mins;
2800 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2801 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2804 png_uint_32 lmhi, lmlo;
2805 lmlo = lmins & PNG_LOMASK;
2806 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2808 for (j = 0; j < num_p_filters; j++)
2810 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_AVG)
2812 lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2815 lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2820 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
2823 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
2826 if (lmhi > PNG_HIMASK)
2830 lmins = (lmhi << PNG_HISHIFT) + lmlo;
2834 for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
2835 pp = prev_row + 1; i < bpp; i++)
2837 v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
2839 sum += (v < 128) ? v : 256 - v;
2842 for (lp = row_buf + 1; i < row_bytes; i++)
2845 (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) & 0xff);
2847 sum += (v < 128) ? v : 256 - v;
2849 if (sum > lmins) /* We are already worse, don't continue. */
2853 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2854 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2857 png_uint_32 sumhi, sumlo;
2858 sumlo = sum & PNG_LOMASK;
2859 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2861 for (j = 0; j < num_p_filters; j++)
2863 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
2865 sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2868 sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2873 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
2876 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
2879 if (sumhi > PNG_HIMASK)
2883 sum = (sumhi << PNG_HISHIFT) + sumlo;
2890 best_row = png_ptr->avg_row;
2895 if (filter_to_do == PNG_FILTER_PAETH)
2897 png_bytep rp, dp, pp, cp, lp;
2900 for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
2901 pp = prev_row + 1; i < bpp; i++)
2903 *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2906 for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
2908 int a, b, c, pa, pb, pc, p;
2922 pa = p < 0 ? -p : p;
2923 pb = pc < 0 ? -pc : pc;
2924 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
2927 p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
2929 *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
2931 best_row = png_ptr->paeth_row;
2934 else if (filter_to_do & PNG_FILTER_PAETH)
2936 png_bytep rp, dp, pp, cp, lp;
2937 png_uint_32 sum = 0, lmins = mins;
2941 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2942 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2945 png_uint_32 lmhi, lmlo;
2946 lmlo = lmins & PNG_LOMASK;
2947 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2949 for (j = 0; j < num_p_filters; j++)
2951 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
2953 lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2956 lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2961 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2964 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2967 if (lmhi > PNG_HIMASK)
2971 lmins = (lmhi << PNG_HISHIFT) + lmlo;
2975 for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
2976 pp = prev_row + 1; i < bpp; i++)
2978 v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2980 sum += (v < 128) ? v : 256 - v;
2983 for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
2985 int a, b, c, pa, pb, pc, p;
2991 #ifndef PNG_SLOW_PAETH
2999 pa = p < 0 ? -p : p;
3000 pb = pc < 0 ? -pc : pc;
3001 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
3003 p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
3004 #else /* PNG_SLOW_PAETH */
3010 if (pa <= pb && pa <= pc)
3018 #endif /* PNG_SLOW_PAETH */
3020 v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
3022 sum += (v < 128) ? v : 256 - v;
3024 if (sum > lmins) /* We are already worse, don't continue. */
3028 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
3029 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
3032 png_uint_32 sumhi, sumlo;
3033 sumlo = sum & PNG_LOMASK;
3034 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
3036 for (j = 0; j < num_p_filters; j++)
3038 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
3040 sumlo = (sumlo * png_ptr->filter_weights[j]) >>
3043 sumhi = (sumhi * png_ptr->filter_weights[j]) >>
3048 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
3051 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
3054 if (sumhi > PNG_HIMASK)
3058 sum = (sumhi << PNG_HISHIFT) + sumlo;
3064 best_row = png_ptr->paeth_row;
3067 #endif /* PNG_WRITE_FILTER_SUPPORTED */
3069 /* Do the actual writing of the filtered row data from the chosen filter. */
3070 png_write_filtered_row(png_ptr, best_row, row_info->rowbytes+1);
3072 #ifdef PNG_WRITE_FILTER_SUPPORTED
3073 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
3074 /* Save the type of filter we picked this time for future calculations */
3075 if (png_ptr->num_prev_filters > 0)
3079 for (j = 1; j < num_p_filters; j++)
3081 png_ptr->prev_filters[j] = png_ptr->prev_filters[j - 1];
3084 png_ptr->prev_filters[j] = best_row[0];
3087 #endif /* PNG_WRITE_FILTER_SUPPORTED */
3091 /* Do the actual writing of a previously filtered row. */
3093 png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row,
3094 png_size_t avail/*includes filter byte*/)
3096 png_debug(1, "in png_write_filtered_row");
3098 png_debug1(2, "filter = %d", filtered_row[0]);
3099 /* Set up the zlib input buffer */
3101 png_ptr->zstream.next_in = filtered_row;
3102 png_ptr->zstream.avail_in = 0;
3103 /* Repeat until we have compressed all the data */
3106 int ret; /* Return of zlib */
3108 /* Record the number of bytes available - zlib supports at least 65535
3109 * bytes at one step, depending on the size of the zlib type 'uInt', the
3110 * maximum size zlib can write at once is ZLIB_IO_MAX (from pngpriv.h).
3111 * Use this because on 16 bit systems 'rowbytes' can be up to 65536 (i.e.
3112 * one more than 16 bits) and, in this case 'rowbytes+1' can overflow a
3113 * uInt. ZLIB_IO_MAX can be safely reduced to cause zlib to be called
3114 * with smaller chunks of data.
3116 if (png_ptr->zstream.avail_in == 0)
3118 if (avail > ZLIB_IO_MAX)
3120 png_ptr->zstream.avail_in = ZLIB_IO_MAX;
3121 avail -= ZLIB_IO_MAX;
3126 /* So this will fit in the available uInt space: */
3127 png_ptr->zstream.avail_in = (uInt)avail;
3132 /* Compress the data */
3133 ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
3135 /* Check for compression errors */
3138 if (png_ptr->zstream.msg != NULL)
3139 png_error(png_ptr, png_ptr->zstream.msg);
3142 png_error(png_ptr, "zlib error");
3145 /* See if it is time to write another IDAT */
3146 if (!(png_ptr->zstream.avail_out))
3148 /* Write the IDAT and reset the zlib output buffer */
3149 png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
3151 /* Repeat until all data has been compressed */
3152 } while (avail > 0 || png_ptr->zstream.avail_in > 0);
3154 /* Swap the current and previous rows */
3155 if (png_ptr->prev_row != NULL)
3159 tptr = png_ptr->prev_row;
3160 png_ptr->prev_row = png_ptr->row_buf;
3161 png_ptr->row_buf = tptr;
3164 /* Finish row - updates counters and flushes zlib if last row */
3165 png_write_finish_row(png_ptr);
3167 #ifdef PNG_WRITE_FLUSH_SUPPORTED
3168 png_ptr->flush_rows++;
3170 if (png_ptr->flush_dist > 0 &&
3171 png_ptr->flush_rows >= png_ptr->flush_dist)
3173 png_write_flush(png_ptr);
3177 #endif /* PNG_WRITE_SUPPORTED */