2 /* pngwutil.c - utilities to write a PNG file
4 * Last changed in libpng 1.5.6 [November 3, 2011]
5 * Copyright (c) 1998-2011 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,
464 (comp->max_output_ptr * png_sizeof(png_charpp)));
466 png_memcpy(comp->output_ptr, old_ptr, old_max
467 * png_sizeof(png_charp));
469 png_free(png_ptr, old_ptr);
472 comp->output_ptr = (png_bytepp)png_malloc(png_ptr,
474 (comp->max_output_ptr * png_sizeof(png_charp)));
478 comp->output_ptr[comp->num_output_ptr] =
479 (png_bytep)png_malloc(png_ptr,
480 (png_alloc_size_t)png_ptr->zbuf_size);
482 png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
485 comp->num_output_ptr++;
487 /* and reset the buffer */
488 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
489 png_ptr->zstream.next_out = png_ptr->zbuf;
491 /* Continue until we don't have any more to compress */
492 } while (png_ptr->zstream.avail_in);
494 /* Finish the compression */
497 /* Tell zlib we are finished */
498 ret = deflate(&png_ptr->zstream, Z_FINISH);
502 /* Check to see if we need more room */
503 if (!(png_ptr->zstream.avail_out))
505 /* Check to make sure our output array has room */
506 if (comp->num_output_ptr >= comp->max_output_ptr)
510 old_max = comp->max_output_ptr;
511 comp->max_output_ptr = comp->num_output_ptr + 4;
512 if (comp->output_ptr != NULL)
516 old_ptr = comp->output_ptr;
518 /* This could be optimized to realloc() */
519 comp->output_ptr = (png_bytepp)png_malloc(png_ptr,
520 (png_alloc_size_t)(comp->max_output_ptr *
521 png_sizeof(png_charp)));
523 png_memcpy(comp->output_ptr, old_ptr,
524 old_max * png_sizeof(png_charp));
526 png_free(png_ptr, old_ptr);
530 comp->output_ptr = (png_bytepp)png_malloc(png_ptr,
531 (png_alloc_size_t)(comp->max_output_ptr *
532 png_sizeof(png_charp)));
536 comp->output_ptr[comp->num_output_ptr] =
537 (png_bytep)png_malloc(png_ptr,
538 (png_alloc_size_t)png_ptr->zbuf_size);
540 png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
543 comp->num_output_ptr++;
545 /* and reset the buffer pointers */
546 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
547 png_ptr->zstream.next_out = png_ptr->zbuf;
550 else if (ret != Z_STREAM_END)
552 /* We got an error */
553 if (png_ptr->zstream.msg != NULL)
554 png_error(png_ptr, png_ptr->zstream.msg);
557 png_error(png_ptr, "zlib error");
559 } while (ret != Z_STREAM_END);
561 /* Text length is number of buffers plus last buffer */
562 text_len = png_ptr->zbuf_size * comp->num_output_ptr;
564 if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
565 text_len += png_ptr->zbuf_size - (png_size_t)png_ptr->zstream.avail_out;
567 return((int)text_len);
570 /* Ship the compressed text out via chunk writes */
571 static void /* PRIVATE */
572 png_write_compressed_data_out(png_structp png_ptr, compression_state *comp)
576 /* Handle the no-compression case */
579 png_write_chunk_data(png_ptr, comp->input, comp->input_len);
584 #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
585 /* The zbuf_size test is because the code below doesn't work if zbuf_size is
586 * '1'; simply skip it to avoid memory overwrite.
588 if (comp->input_len >= 2 && comp->input_len < 16384 && png_ptr->zbuf_size > 1)
590 unsigned int z_cmf; /* zlib compression method and flags */
592 /* Optimize the CMF field in the zlib stream. This hack of the zlib
593 * stream is compliant to the stream specification.
596 if (comp->num_output_ptr)
597 z_cmf = comp->output_ptr[0][0];
599 z_cmf = png_ptr->zbuf[0];
601 if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
603 unsigned int z_cinfo;
604 unsigned int half_z_window_size;
605 png_size_t uncompressed_text_size = comp->input_len;
607 z_cinfo = z_cmf >> 4;
608 half_z_window_size = 1 << (z_cinfo + 7);
610 while (uncompressed_text_size <= half_z_window_size &&
611 half_z_window_size >= 256)
614 half_z_window_size >>= 1;
617 z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
619 if (comp->num_output_ptr)
622 if (comp->output_ptr[0][0] != z_cmf)
626 comp->output_ptr[0][0] = (png_byte)z_cmf;
627 tmp = comp->output_ptr[0][1] & 0xe0;
628 tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
629 comp->output_ptr[0][1] = (png_byte)tmp;
636 png_ptr->zbuf[0] = (png_byte)z_cmf;
637 tmp = png_ptr->zbuf[1] & 0xe0;
638 tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
639 png_ptr->zbuf[1] = (png_byte)tmp;
645 "Invalid zlib compression method or flags in non-IDAT chunk");
647 #endif /* PNG_WRITE_OPTIMIZE_CMF_SUPPORTED */
649 /* Write saved output buffers, if any */
650 for (i = 0; i < comp->num_output_ptr; i++)
652 png_write_chunk_data(png_ptr, comp->output_ptr[i],
653 (png_size_t)png_ptr->zbuf_size);
655 png_free(png_ptr, comp->output_ptr[i]);
658 if (comp->max_output_ptr != 0)
659 png_free(png_ptr, comp->output_ptr);
661 /* Write anything left in zbuf */
662 if (png_ptr->zstream.avail_out < (png_uint_32)png_ptr->zbuf_size)
663 png_write_chunk_data(png_ptr, png_ptr->zbuf,
664 (png_size_t)(png_ptr->zbuf_size - png_ptr->zstream.avail_out));
666 /* Reset zlib for another zTXt/iTXt or image data */
667 png_zlib_release(png_ptr);
669 #endif /* PNG_WRITE_COMPRESSED_TEXT_SUPPORTED */
671 /* Write the IHDR chunk, and update the png_struct with the necessary
672 * information. Note that the rest of this code depends upon this
673 * information being correct.
676 png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
677 int bit_depth, int color_type, int compression_type, int filter_type,
680 png_byte buf[13]; /* Buffer to store the IHDR info */
682 png_debug(1, "in png_write_IHDR");
684 /* Check that we have valid input data from the application info */
687 case PNG_COLOR_TYPE_GRAY:
694 #ifdef PNG_WRITE_16BIT_SUPPORTED
697 png_ptr->channels = 1; break;
701 "Invalid bit depth for grayscale image");
705 case PNG_COLOR_TYPE_RGB:
706 #ifdef PNG_WRITE_16BIT_SUPPORTED
707 if (bit_depth != 8 && bit_depth != 16)
711 png_error(png_ptr, "Invalid bit depth for RGB image");
713 png_ptr->channels = 3;
716 case PNG_COLOR_TYPE_PALETTE:
723 png_ptr->channels = 1;
727 png_error(png_ptr, "Invalid bit depth for paletted image");
731 case PNG_COLOR_TYPE_GRAY_ALPHA:
732 if (bit_depth != 8 && bit_depth != 16)
733 png_error(png_ptr, "Invalid bit depth for grayscale+alpha image");
735 png_ptr->channels = 2;
738 case PNG_COLOR_TYPE_RGB_ALPHA:
739 #ifdef PNG_WRITE_16BIT_SUPPORTED
740 if (bit_depth != 8 && bit_depth != 16)
744 png_error(png_ptr, "Invalid bit depth for RGBA image");
746 png_ptr->channels = 4;
750 png_error(png_ptr, "Invalid image color type specified");
753 if (compression_type != PNG_COMPRESSION_TYPE_BASE)
755 png_warning(png_ptr, "Invalid compression type specified");
756 compression_type = PNG_COMPRESSION_TYPE_BASE;
759 /* Write filter_method 64 (intrapixel differencing) only if
760 * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
761 * 2. Libpng did not write a PNG signature (this filter_method is only
762 * used in PNG datastreams that are embedded in MNG datastreams) and
763 * 3. The application called png_permit_mng_features with a mask that
764 * included PNG_FLAG_MNG_FILTER_64 and
765 * 4. The filter_method is 64 and
766 * 5. The color_type is RGB or RGBA
769 #ifdef PNG_MNG_FEATURES_SUPPORTED
770 !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
771 ((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE) == 0) &&
772 (color_type == PNG_COLOR_TYPE_RGB ||
773 color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&
774 (filter_type == PNG_INTRAPIXEL_DIFFERENCING)) &&
776 filter_type != PNG_FILTER_TYPE_BASE)
778 png_warning(png_ptr, "Invalid filter type specified");
779 filter_type = PNG_FILTER_TYPE_BASE;
782 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
783 if (interlace_type != PNG_INTERLACE_NONE &&
784 interlace_type != PNG_INTERLACE_ADAM7)
786 png_warning(png_ptr, "Invalid interlace type specified");
787 interlace_type = PNG_INTERLACE_ADAM7;
790 interlace_type=PNG_INTERLACE_NONE;
793 /* Save the relevent information */
794 png_ptr->bit_depth = (png_byte)bit_depth;
795 png_ptr->color_type = (png_byte)color_type;
796 png_ptr->interlaced = (png_byte)interlace_type;
797 #ifdef PNG_MNG_FEATURES_SUPPORTED
798 png_ptr->filter_type = (png_byte)filter_type;
800 png_ptr->compression_type = (png_byte)compression_type;
801 png_ptr->width = width;
802 png_ptr->height = height;
804 png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels);
805 png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width);
806 /* Set the usr info, so any transformations can modify it */
807 png_ptr->usr_width = png_ptr->width;
808 png_ptr->usr_bit_depth = png_ptr->bit_depth;
809 png_ptr->usr_channels = png_ptr->channels;
811 /* Pack the header information into the buffer */
812 png_save_uint_32(buf, width);
813 png_save_uint_32(buf + 4, height);
814 buf[8] = (png_byte)bit_depth;
815 buf[9] = (png_byte)color_type;
816 buf[10] = (png_byte)compression_type;
817 buf[11] = (png_byte)filter_type;
818 buf[12] = (png_byte)interlace_type;
820 /* Write the chunk */
821 png_write_complete_chunk(png_ptr, png_IHDR, buf, (png_size_t)13);
823 /* Initialize zlib with PNG info */
824 png_ptr->zstream.zalloc = png_zalloc;
825 png_ptr->zstream.zfree = png_zfree;
826 png_ptr->zstream.opaque = (voidpf)png_ptr;
828 if (!(png_ptr->do_filter))
830 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
831 png_ptr->bit_depth < 8)
832 png_ptr->do_filter = PNG_FILTER_NONE;
835 png_ptr->do_filter = PNG_ALL_FILTERS;
838 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY))
840 if (png_ptr->do_filter != PNG_FILTER_NONE)
841 png_ptr->zlib_strategy = Z_FILTERED;
844 png_ptr->zlib_strategy = Z_DEFAULT_STRATEGY;
847 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_LEVEL))
848 png_ptr->zlib_level = Z_DEFAULT_COMPRESSION;
850 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL))
851 png_ptr->zlib_mem_level = 8;
853 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS))
854 png_ptr->zlib_window_bits = 15;
856 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_METHOD))
857 png_ptr->zlib_method = 8;
859 #ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
860 #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
861 if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_STRATEGY))
862 png_ptr->zlib_text_strategy = Z_DEFAULT_STRATEGY;
864 if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_LEVEL))
865 png_ptr->zlib_text_level = png_ptr->zlib_level;
867 if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_MEM_LEVEL))
868 png_ptr->zlib_text_mem_level = png_ptr->zlib_mem_level;
870 if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_WINDOW_BITS))
871 png_ptr->zlib_text_window_bits = png_ptr->zlib_window_bits;
873 if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_METHOD))
874 png_ptr->zlib_text_method = png_ptr->zlib_method;
876 png_ptr->zlib_text_strategy = Z_DEFAULT_STRATEGY;
877 png_ptr->zlib_text_level = png_ptr->zlib_level;
878 png_ptr->zlib_text_mem_level = png_ptr->zlib_mem_level;
879 png_ptr->zlib_text_window_bits = png_ptr->zlib_window_bits;
880 png_ptr->zlib_text_method = png_ptr->zlib_method;
881 #endif /* PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED */
882 #endif /* PNG_WRITE_COMPRESSED_TEXT_SUPPORTED */
884 /* Record that the compressor has not yet been initialized. */
885 png_ptr->zlib_state = PNG_ZLIB_UNINITIALIZED;
887 png_ptr->mode = PNG_HAVE_IHDR; /* not READY_FOR_ZTXT */
890 /* Write the palette. We are careful not to trust png_color to be in the
891 * correct order for PNG, so people can redefine it to any convenient
895 png_write_PLTE(png_structp png_ptr, png_const_colorp palette,
899 png_const_colorp pal_ptr;
902 png_debug(1, "in png_write_PLTE");
905 #ifdef PNG_MNG_FEATURES_SUPPORTED
906 !(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) &&
908 num_pal == 0) || num_pal > 256)
910 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
912 png_error(png_ptr, "Invalid number of colors in palette");
917 png_warning(png_ptr, "Invalid number of colors in palette");
922 if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))
925 "Ignoring request to write a PLTE chunk in grayscale PNG");
930 png_ptr->num_palette = (png_uint_16)num_pal;
931 png_debug1(3, "num_palette = %d", png_ptr->num_palette);
933 png_write_chunk_header(png_ptr, png_PLTE, (png_uint_32)(num_pal * 3));
934 #ifdef PNG_POINTER_INDEXING_SUPPORTED
936 for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++)
938 buf[0] = pal_ptr->red;
939 buf[1] = pal_ptr->green;
940 buf[2] = pal_ptr->blue;
941 png_write_chunk_data(png_ptr, buf, (png_size_t)3);
945 /* This is a little slower but some buggy compilers need to do this
950 for (i = 0; i < num_pal; i++)
952 buf[0] = pal_ptr[i].red;
953 buf[1] = pal_ptr[i].green;
954 buf[2] = pal_ptr[i].blue;
955 png_write_chunk_data(png_ptr, buf, (png_size_t)3);
959 png_write_chunk_end(png_ptr);
960 png_ptr->mode |= PNG_HAVE_PLTE;
963 /* Write an IDAT chunk */
965 png_write_IDAT(png_structp png_ptr, png_bytep data, png_size_t length)
967 png_debug(1, "in png_write_IDAT");
969 #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
970 if (!(png_ptr->mode & PNG_HAVE_IDAT) &&
971 png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
973 /* Optimize the CMF field in the zlib stream. This hack of the zlib
974 * stream is compliant to the stream specification.
976 unsigned int z_cmf = data[0]; /* zlib compression method and flags */
978 if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
980 /* Avoid memory underflows and multiplication overflows.
982 * The conditions below are practically always satisfied;
983 * however, they still must be checked.
986 png_ptr->height < 16384 && png_ptr->width < 16384)
988 /* Compute the maximum possible length of the datastream */
990 /* Number of pixels, plus for each row a filter byte
991 * and possibly a padding byte, so increase the maximum
992 * size to account for these.
994 unsigned int z_cinfo;
995 unsigned int half_z_window_size;
996 png_uint_32 uncompressed_idat_size = png_ptr->height *
998 png_ptr->channels * png_ptr->bit_depth + 15) >> 3);
1000 /* If it's interlaced, each block of 8 rows is sent as up to
1001 * 14 rows, i.e., 6 additional rows, each with a filter byte
1002 * and possibly a padding byte
1004 if (png_ptr->interlaced)
1005 uncompressed_idat_size += ((png_ptr->height + 7)/8) *
1006 (png_ptr->bit_depth < 8 ? 12 : 6);
1008 z_cinfo = z_cmf >> 4;
1009 half_z_window_size = 1 << (z_cinfo + 7);
1011 while (uncompressed_idat_size <= half_z_window_size &&
1012 half_z_window_size >= 256)
1015 half_z_window_size >>= 1;
1018 z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
1020 if (data[0] != z_cmf)
1023 data[0] = (png_byte)z_cmf;
1024 tmp = data[1] & 0xe0;
1025 tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
1026 data[1] = (png_byte)tmp;
1033 "Invalid zlib compression method or flags in IDAT");
1035 #endif /* PNG_WRITE_OPTIMIZE_CMF_SUPPORTED */
1037 png_write_complete_chunk(png_ptr, png_IDAT, data, length);
1038 png_ptr->mode |= PNG_HAVE_IDAT;
1040 /* Prior to 1.5.4 this code was replicated in every caller (except at the
1041 * end, where it isn't technically necessary). Since this function has
1042 * flushed the data we can safely reset the zlib output buffer here.
1044 png_ptr->zstream.next_out = png_ptr->zbuf;
1045 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1048 /* Write an IEND chunk */
1050 png_write_IEND(png_structp png_ptr)
1052 png_debug(1, "in png_write_IEND");
1054 png_write_complete_chunk(png_ptr, png_IEND, NULL, (png_size_t)0);
1055 png_ptr->mode |= PNG_HAVE_IEND;
1058 #ifdef PNG_WRITE_gAMA_SUPPORTED
1059 /* Write a gAMA chunk */
1061 png_write_gAMA_fixed(png_structp png_ptr, png_fixed_point file_gamma)
1065 png_debug(1, "in png_write_gAMA");
1067 /* file_gamma is saved in 1/100,000ths */
1068 png_save_uint_32(buf, (png_uint_32)file_gamma);
1069 png_write_complete_chunk(png_ptr, png_gAMA, buf, (png_size_t)4);
1073 #ifdef PNG_WRITE_sRGB_SUPPORTED
1074 /* Write a sRGB chunk */
1076 png_write_sRGB(png_structp png_ptr, int srgb_intent)
1080 png_debug(1, "in png_write_sRGB");
1082 if (srgb_intent >= PNG_sRGB_INTENT_LAST)
1083 png_warning(png_ptr,
1084 "Invalid sRGB rendering intent specified");
1086 buf[0]=(png_byte)srgb_intent;
1087 png_write_complete_chunk(png_ptr, png_sRGB, buf, (png_size_t)1);
1091 #ifdef PNG_WRITE_iCCP_SUPPORTED
1092 /* Write an iCCP chunk */
1094 png_write_iCCP(png_structp png_ptr, png_const_charp name, int compression_type,
1095 png_const_charp profile, int profile_len)
1097 png_size_t name_len;
1099 compression_state comp;
1100 int embedded_profile_len = 0;
1102 png_debug(1, "in png_write_iCCP");
1104 comp.num_output_ptr = 0;
1105 comp.max_output_ptr = 0;
1106 comp.output_ptr = NULL;
1110 if ((name_len = png_check_keyword(png_ptr, name, &new_name)) == 0)
1113 if (compression_type != PNG_COMPRESSION_TYPE_BASE)
1114 png_warning(png_ptr, "Unknown compression type in iCCP chunk");
1116 if (profile == NULL)
1119 if (profile_len > 3)
1120 embedded_profile_len =
1121 ((*( (png_const_bytep)profile ))<<24) |
1122 ((*( (png_const_bytep)profile + 1))<<16) |
1123 ((*( (png_const_bytep)profile + 2))<< 8) |
1124 ((*( (png_const_bytep)profile + 3)) );
1126 if (embedded_profile_len < 0)
1128 png_warning(png_ptr,
1129 "Embedded profile length in iCCP chunk is negative");
1131 png_free(png_ptr, new_name);
1135 if (profile_len < embedded_profile_len)
1137 png_warning(png_ptr,
1138 "Embedded profile length too large in iCCP chunk");
1140 png_free(png_ptr, new_name);
1144 if (profile_len > embedded_profile_len)
1146 png_warning(png_ptr,
1147 "Truncating profile to actual length in iCCP chunk");
1149 profile_len = embedded_profile_len;
1153 profile_len = png_text_compress(png_ptr, profile,
1154 (png_size_t)profile_len, PNG_COMPRESSION_TYPE_BASE, &comp);
1156 /* Make sure we include the NULL after the name and the compression type */
1157 png_write_chunk_header(png_ptr, png_iCCP,
1158 (png_uint_32)(name_len + profile_len + 2));
1160 new_name[name_len + 1] = 0x00;
1162 png_write_chunk_data(png_ptr, (png_bytep)new_name,
1163 (png_size_t)(name_len + 2));
1167 comp.input_len = profile_len;
1168 png_write_compressed_data_out(png_ptr, &comp);
1171 png_write_chunk_end(png_ptr);
1172 png_free(png_ptr, new_name);
1176 #ifdef PNG_WRITE_sPLT_SUPPORTED
1177 /* Write a sPLT chunk */
1179 png_write_sPLT(png_structp png_ptr, png_const_sPLT_tp spalette)
1181 png_size_t name_len;
1183 png_byte entrybuf[10];
1184 png_size_t entry_size = (spalette->depth == 8 ? 6 : 10);
1185 png_size_t palette_size = entry_size * spalette->nentries;
1187 #ifndef PNG_POINTER_INDEXING_SUPPORTED
1191 png_debug(1, "in png_write_sPLT");
1193 if ((name_len = png_check_keyword(png_ptr,spalette->name, &new_name))==0)
1196 /* Make sure we include the NULL after the name */
1197 png_write_chunk_header(png_ptr, png_sPLT,
1198 (png_uint_32)(name_len + 2 + palette_size));
1200 png_write_chunk_data(png_ptr, (png_bytep)new_name,
1201 (png_size_t)(name_len + 1));
1203 png_write_chunk_data(png_ptr, &spalette->depth, (png_size_t)1);
1205 /* Loop through each palette entry, writing appropriately */
1206 #ifdef PNG_POINTER_INDEXING_SUPPORTED
1207 for (ep = spalette->entries; ep<spalette->entries + spalette->nentries; ep++)
1209 if (spalette->depth == 8)
1211 entrybuf[0] = (png_byte)ep->red;
1212 entrybuf[1] = (png_byte)ep->green;
1213 entrybuf[2] = (png_byte)ep->blue;
1214 entrybuf[3] = (png_byte)ep->alpha;
1215 png_save_uint_16(entrybuf + 4, ep->frequency);
1220 png_save_uint_16(entrybuf + 0, ep->red);
1221 png_save_uint_16(entrybuf + 2, ep->green);
1222 png_save_uint_16(entrybuf + 4, ep->blue);
1223 png_save_uint_16(entrybuf + 6, ep->alpha);
1224 png_save_uint_16(entrybuf + 8, ep->frequency);
1227 png_write_chunk_data(png_ptr, entrybuf, (png_size_t)entry_size);
1230 ep=spalette->entries;
1231 for (i = 0; i>spalette->nentries; i++)
1233 if (spalette->depth == 8)
1235 entrybuf[0] = (png_byte)ep[i].red;
1236 entrybuf[1] = (png_byte)ep[i].green;
1237 entrybuf[2] = (png_byte)ep[i].blue;
1238 entrybuf[3] = (png_byte)ep[i].alpha;
1239 png_save_uint_16(entrybuf + 4, ep[i].frequency);
1244 png_save_uint_16(entrybuf + 0, ep[i].red);
1245 png_save_uint_16(entrybuf + 2, ep[i].green);
1246 png_save_uint_16(entrybuf + 4, ep[i].blue);
1247 png_save_uint_16(entrybuf + 6, ep[i].alpha);
1248 png_save_uint_16(entrybuf + 8, ep[i].frequency);
1251 png_write_chunk_data(png_ptr, entrybuf, (png_size_t)entry_size);
1255 png_write_chunk_end(png_ptr);
1256 png_free(png_ptr, new_name);
1260 #ifdef PNG_WRITE_sBIT_SUPPORTED
1261 /* Write the sBIT chunk */
1263 png_write_sBIT(png_structp 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)
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)
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_structp png_ptr, png_fixed_point white_x,
1323 png_fixed_point white_y, png_fixed_point red_x, png_fixed_point red_y,
1324 png_fixed_point green_x, png_fixed_point green_y, png_fixed_point blue_x,
1325 png_fixed_point blue_y)
1329 png_debug(1, "in png_write_cHRM");
1331 /* Each value is saved in 1/100,000ths */
1332 #ifdef PNG_CHECK_cHRM_SUPPORTED
1333 if (png_check_cHRM_fixed(png_ptr, white_x, white_y, red_x, red_y,
1334 green_x, green_y, blue_x, blue_y))
1337 png_save_uint_32(buf, (png_uint_32)white_x);
1338 png_save_uint_32(buf + 4, (png_uint_32)white_y);
1340 png_save_uint_32(buf + 8, (png_uint_32)red_x);
1341 png_save_uint_32(buf + 12, (png_uint_32)red_y);
1343 png_save_uint_32(buf + 16, (png_uint_32)green_x);
1344 png_save_uint_32(buf + 20, (png_uint_32)green_y);
1346 png_save_uint_32(buf + 24, (png_uint_32)blue_x);
1347 png_save_uint_32(buf + 28, (png_uint_32)blue_y);
1349 png_write_complete_chunk(png_ptr, png_cHRM, buf, (png_size_t)32);
1354 #ifdef PNG_WRITE_tRNS_SUPPORTED
1355 /* Write the tRNS chunk */
1357 png_write_tRNS(png_structp png_ptr, png_const_bytep trans_alpha,
1358 png_const_color_16p tran, int num_trans, int color_type)
1362 png_debug(1, "in png_write_tRNS");
1364 if (color_type == PNG_COLOR_TYPE_PALETTE)
1366 if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette)
1368 png_warning(png_ptr, "Invalid number of transparent colors specified");
1372 /* Write the chunk out as it is */
1373 png_write_complete_chunk(png_ptr, png_tRNS, trans_alpha, (png_size_t)num_trans);
1376 else if (color_type == PNG_COLOR_TYPE_GRAY)
1378 /* One 16 bit value */
1379 if (tran->gray >= (1 << png_ptr->bit_depth))
1381 png_warning(png_ptr,
1382 "Ignoring attempt to write tRNS chunk out-of-range for bit_depth");
1387 png_save_uint_16(buf, tran->gray);
1388 png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)2);
1391 else if (color_type == PNG_COLOR_TYPE_RGB)
1393 /* Three 16 bit values */
1394 png_save_uint_16(buf, tran->red);
1395 png_save_uint_16(buf + 2, tran->green);
1396 png_save_uint_16(buf + 4, tran->blue);
1397 #ifdef PNG_WRITE_16BIT_SUPPORTED
1398 if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))
1400 if (buf[0] | buf[2] | buf[4])
1403 png_warning(png_ptr,
1404 "Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8");
1408 png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)6);
1413 png_warning(png_ptr, "Can't write tRNS with an alpha channel");
1418 #ifdef PNG_WRITE_bKGD_SUPPORTED
1419 /* Write the background chunk */
1421 png_write_bKGD(png_structp png_ptr, png_const_color_16p back, int color_type)
1425 png_debug(1, "in png_write_bKGD");
1427 if (color_type == PNG_COLOR_TYPE_PALETTE)
1430 #ifdef PNG_MNG_FEATURES_SUPPORTED
1431 (png_ptr->num_palette ||
1432 (!(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE))) &&
1434 back->index >= png_ptr->num_palette)
1436 png_warning(png_ptr, "Invalid background palette index");
1440 buf[0] = back->index;
1441 png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)1);
1444 else if (color_type & PNG_COLOR_MASK_COLOR)
1446 png_save_uint_16(buf, back->red);
1447 png_save_uint_16(buf + 2, back->green);
1448 png_save_uint_16(buf + 4, back->blue);
1449 #ifdef PNG_WRITE_16BIT_SUPPORTED
1450 if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))
1452 if (buf[0] | buf[2] | buf[4])
1455 png_warning(png_ptr,
1456 "Ignoring attempt to write 16-bit bKGD chunk when bit_depth is 8");
1461 png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)6);
1466 if (back->gray >= (1 << png_ptr->bit_depth))
1468 png_warning(png_ptr,
1469 "Ignoring attempt to write bKGD chunk out-of-range for bit_depth");
1474 png_save_uint_16(buf, back->gray);
1475 png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)2);
1480 #ifdef PNG_WRITE_hIST_SUPPORTED
1481 /* Write the histogram */
1483 png_write_hIST(png_structp png_ptr, png_const_uint_16p hist, int num_hist)
1488 png_debug(1, "in png_write_hIST");
1490 if (num_hist > (int)png_ptr->num_palette)
1492 png_debug2(3, "num_hist = %d, num_palette = %d", num_hist,
1493 png_ptr->num_palette);
1495 png_warning(png_ptr, "Invalid number of histogram entries specified");
1499 png_write_chunk_header(png_ptr, png_hIST, (png_uint_32)(num_hist * 2));
1501 for (i = 0; i < num_hist; i++)
1503 png_save_uint_16(buf, hist[i]);
1504 png_write_chunk_data(png_ptr, buf, (png_size_t)2);
1507 png_write_chunk_end(png_ptr);
1511 #if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \
1512 defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
1513 /* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification,
1514 * and if invalid, correct the keyword rather than discarding the entire
1515 * chunk. The PNG 1.0 specification requires keywords 1-79 characters in
1516 * length, forbids leading or trailing whitespace, multiple internal spaces,
1517 * and the non-break space (0x80) from ISO 8859-1. Returns keyword length.
1519 * The new_key is allocated to hold the corrected keyword and must be freed
1520 * by the calling routine. This avoids problems with trying to write to
1521 * static keywords without having to have duplicate copies of the strings.
1523 png_size_t /* PRIVATE */
1524 png_check_keyword(png_structp png_ptr, png_const_charp key, png_charpp new_key)
1527 png_const_charp ikp;
1532 png_debug(1, "in png_check_keyword");
1536 if (key == NULL || (key_len = png_strlen(key)) == 0)
1538 png_warning(png_ptr, "zero length keyword");
1539 return ((png_size_t)0);
1542 png_debug1(2, "Keyword to be checked is '%s'", key);
1544 *new_key = (png_charp)png_malloc_warn(png_ptr, (png_uint_32)(key_len + 2));
1546 if (*new_key == NULL)
1548 png_warning(png_ptr, "Out of memory while procesing keyword");
1549 return ((png_size_t)0);
1552 /* Replace non-printing characters with a blank and print a warning */
1553 for (ikp = key, dp = *new_key; *ikp != '\0'; ikp++, dp++)
1555 if ((png_byte)*ikp < 0x20 ||
1556 ((png_byte)*ikp > 0x7E && (png_byte)*ikp < 0xA1))
1558 PNG_WARNING_PARAMETERS(p)
1560 png_warning_parameter_unsigned(p, 1, PNG_NUMBER_FORMAT_02x,
1562 png_formatted_warning(png_ptr, p, "invalid keyword character 0x@1");
1573 /* Remove any trailing white space. */
1574 kp = *new_key + key_len - 1;
1577 png_warning(png_ptr, "trailing spaces removed from keyword");
1586 /* Remove any leading white space. */
1590 png_warning(png_ptr, "leading spaces removed from keyword");
1599 png_debug1(2, "Checking for multiple internal spaces in '%s'", kp);
1601 /* Remove multiple internal spaces. */
1602 for (kflag = 0, dp = *new_key; *kp != '\0'; kp++)
1604 if (*kp == ' ' && kflag == 0)
1610 else if (*kp == ' ')
1624 png_warning(png_ptr, "extra interior spaces removed from keyword");
1628 png_free(png_ptr, *new_key);
1629 png_warning(png_ptr, "Zero length keyword");
1634 png_warning(png_ptr, "keyword length must be 1 - 79 characters");
1635 (*new_key)[79] = '\0';
1643 #ifdef PNG_WRITE_tEXt_SUPPORTED
1644 /* Write a tEXt chunk */
1646 png_write_tEXt(png_structp png_ptr, png_const_charp key, png_const_charp text,
1647 png_size_t text_len)
1652 png_debug(1, "in png_write_tEXt");
1654 if ((key_len = png_check_keyword(png_ptr, key, &new_key))==0)
1657 if (text == NULL || *text == '\0')
1661 text_len = png_strlen(text);
1663 /* Make sure we include the 0 after the key */
1664 png_write_chunk_header(png_ptr, png_tEXt,
1665 (png_uint_32)(key_len + text_len + 1));
1667 * We leave it to the application to meet PNG-1.0 requirements on the
1668 * contents of the text. PNG-1.0 through PNG-1.2 discourage the use of
1669 * any non-Latin-1 characters except for NEWLINE. ISO PNG will forbid them.
1670 * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1672 png_write_chunk_data(png_ptr, (png_bytep)new_key,
1673 (png_size_t)(key_len + 1));
1676 png_write_chunk_data(png_ptr, (png_const_bytep)text,
1677 (png_size_t)text_len);
1679 png_write_chunk_end(png_ptr);
1680 png_free(png_ptr, new_key);
1684 #ifdef PNG_WRITE_zTXt_SUPPORTED
1685 /* Write a compressed text chunk */
1687 png_write_zTXt(png_structp png_ptr, png_const_charp key, png_const_charp text,
1688 png_size_t text_len, int compression)
1693 compression_state comp;
1695 png_debug(1, "in png_write_zTXt");
1697 comp.num_output_ptr = 0;
1698 comp.max_output_ptr = 0;
1699 comp.output_ptr = NULL;
1703 if ((key_len = png_check_keyword(png_ptr, key, &new_key)) == 0)
1705 png_free(png_ptr, new_key);
1709 if (text == NULL || *text == '\0' || compression==PNG_TEXT_COMPRESSION_NONE)
1711 png_write_tEXt(png_ptr, new_key, text, (png_size_t)0);
1712 png_free(png_ptr, new_key);
1716 text_len = png_strlen(text);
1718 /* Compute the compressed data; do it now for the length */
1719 text_len = png_text_compress(png_ptr, text, text_len, compression,
1722 /* Write start of chunk */
1723 png_write_chunk_header(png_ptr, png_zTXt,
1724 (png_uint_32)(key_len+text_len + 2));
1727 png_write_chunk_data(png_ptr, (png_bytep)new_key,
1728 (png_size_t)(key_len + 1));
1730 png_free(png_ptr, new_key);
1732 buf = (png_byte)compression;
1734 /* Write compression */
1735 png_write_chunk_data(png_ptr, &buf, (png_size_t)1);
1737 /* Write the compressed data */
1738 comp.input_len = text_len;
1739 png_write_compressed_data_out(png_ptr, &comp);
1741 /* Close the chunk */
1742 png_write_chunk_end(png_ptr);
1746 #ifdef PNG_WRITE_iTXt_SUPPORTED
1747 /* Write an iTXt chunk */
1749 png_write_iTXt(png_structp png_ptr, int compression, png_const_charp key,
1750 png_const_charp lang, png_const_charp lang_key, png_const_charp text)
1752 png_size_t lang_len, key_len, lang_key_len, text_len;
1754 png_charp new_key = NULL;
1756 compression_state comp;
1758 png_debug(1, "in png_write_iTXt");
1760 comp.num_output_ptr = 0;
1761 comp.max_output_ptr = 0;
1762 comp.output_ptr = NULL;
1765 if ((key_len = png_check_keyword(png_ptr, key, &new_key)) == 0)
1768 if ((lang_len = png_check_keyword(png_ptr, lang, &new_lang)) == 0)
1770 png_warning(png_ptr, "Empty language field in iTXt chunk");
1775 if (lang_key == NULL)
1779 lang_key_len = png_strlen(lang_key);
1785 text_len = png_strlen(text);
1787 /* Compute the compressed data; do it now for the length */
1788 text_len = png_text_compress(png_ptr, text, text_len, compression - 2,
1792 /* Make sure we include the compression flag, the compression byte,
1793 * and the NULs after the key, lang, and lang_key parts
1796 png_write_chunk_header(png_ptr, png_iTXt, (png_uint_32)(
1797 5 /* comp byte, comp flag, terminators for key, lang and lang_key */
1803 /* We leave it to the application to meet PNG-1.0 requirements on the
1804 * contents of the text. PNG-1.0 through PNG-1.2 discourage the use of
1805 * any non-Latin-1 characters except for NEWLINE. ISO PNG will forbid them.
1806 * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1808 png_write_chunk_data(png_ptr, (png_bytep)new_key, (png_size_t)(key_len + 1));
1810 /* Set the compression flag */
1811 if (compression == PNG_ITXT_COMPRESSION_NONE ||
1812 compression == PNG_TEXT_COMPRESSION_NONE)
1815 else /* compression == PNG_ITXT_COMPRESSION_zTXt */
1818 /* Set the compression method */
1821 png_write_chunk_data(png_ptr, cbuf, (png_size_t)2);
1824 png_write_chunk_data(png_ptr, (new_lang ? (png_const_bytep)new_lang : cbuf),
1825 (png_size_t)(lang_len + 1));
1827 png_write_chunk_data(png_ptr, (lang_key ? (png_const_bytep)lang_key : cbuf),
1828 (png_size_t)(lang_key_len + 1));
1830 png_write_compressed_data_out(png_ptr, &comp);
1832 png_write_chunk_end(png_ptr);
1834 png_free(png_ptr, new_key);
1835 png_free(png_ptr, new_lang);
1839 #ifdef PNG_WRITE_oFFs_SUPPORTED
1840 /* Write the oFFs chunk */
1842 png_write_oFFs(png_structp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
1847 png_debug(1, "in png_write_oFFs");
1849 if (unit_type >= PNG_OFFSET_LAST)
1850 png_warning(png_ptr, "Unrecognized unit type for oFFs chunk");
1852 png_save_int_32(buf, x_offset);
1853 png_save_int_32(buf + 4, y_offset);
1854 buf[8] = (png_byte)unit_type;
1856 png_write_complete_chunk(png_ptr, png_oFFs, buf, (png_size_t)9);
1859 #ifdef PNG_WRITE_pCAL_SUPPORTED
1860 /* Write the pCAL chunk (described in the PNG extensions document) */
1862 png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
1863 png_int_32 X1, int type, int nparams, png_const_charp units,
1866 png_size_t purpose_len, units_len, total_len;
1867 png_size_tp params_len;
1869 png_charp new_purpose;
1872 png_debug1(1, "in png_write_pCAL (%d parameters)", nparams);
1874 if (type >= PNG_EQUATION_LAST)
1875 png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");
1877 purpose_len = png_check_keyword(png_ptr, purpose, &new_purpose) + 1;
1878 png_debug1(3, "pCAL purpose length = %d", (int)purpose_len);
1879 units_len = png_strlen(units) + (nparams == 0 ? 0 : 1);
1880 png_debug1(3, "pCAL units length = %d", (int)units_len);
1881 total_len = purpose_len + units_len + 10;
1883 params_len = (png_size_tp)png_malloc(png_ptr,
1884 (png_alloc_size_t)(nparams * png_sizeof(png_size_t)));
1886 /* Find the length of each parameter, making sure we don't count the
1887 * null terminator for the last parameter.
1889 for (i = 0; i < nparams; i++)
1891 params_len[i] = png_strlen(params[i]) + (i == nparams - 1 ? 0 : 1);
1892 png_debug2(3, "pCAL parameter %d length = %lu", i,
1893 (unsigned long)params_len[i]);
1894 total_len += params_len[i];
1897 png_debug1(3, "pCAL total length = %d", (int)total_len);
1898 png_write_chunk_header(png_ptr, png_pCAL, (png_uint_32)total_len);
1899 png_write_chunk_data(png_ptr, (png_const_bytep)new_purpose, purpose_len);
1900 png_save_int_32(buf, X0);
1901 png_save_int_32(buf + 4, X1);
1902 buf[8] = (png_byte)type;
1903 buf[9] = (png_byte)nparams;
1904 png_write_chunk_data(png_ptr, buf, (png_size_t)10);
1905 png_write_chunk_data(png_ptr, (png_const_bytep)units, (png_size_t)units_len);
1907 png_free(png_ptr, new_purpose);
1909 for (i = 0; i < nparams; i++)
1911 png_write_chunk_data(png_ptr, (png_const_bytep)params[i], params_len[i]);
1914 png_free(png_ptr, params_len);
1915 png_write_chunk_end(png_ptr);
1919 #ifdef PNG_WRITE_sCAL_SUPPORTED
1920 /* Write the sCAL chunk */
1922 png_write_sCAL_s(png_structp png_ptr, int unit, png_const_charp width,
1923 png_const_charp height)
1926 png_size_t wlen, hlen, total_len;
1928 png_debug(1, "in png_write_sCAL_s");
1930 wlen = png_strlen(width);
1931 hlen = png_strlen(height);
1932 total_len = wlen + hlen + 2;
1936 png_warning(png_ptr, "Can't write sCAL (buffer too small)");
1940 buf[0] = (png_byte)unit;
1941 png_memcpy(buf + 1, width, wlen + 1); /* Append the '\0' here */
1942 png_memcpy(buf + wlen + 2, height, hlen); /* Do NOT append the '\0' here */
1944 png_debug1(3, "sCAL total length = %u", (unsigned int)total_len);
1945 png_write_complete_chunk(png_ptr, png_sCAL, buf, total_len);
1949 #ifdef PNG_WRITE_pHYs_SUPPORTED
1950 /* Write the pHYs chunk */
1952 png_write_pHYs(png_structp png_ptr, png_uint_32 x_pixels_per_unit,
1953 png_uint_32 y_pixels_per_unit,
1958 png_debug(1, "in png_write_pHYs");
1960 if (unit_type >= PNG_RESOLUTION_LAST)
1961 png_warning(png_ptr, "Unrecognized unit type for pHYs chunk");
1963 png_save_uint_32(buf, x_pixels_per_unit);
1964 png_save_uint_32(buf + 4, y_pixels_per_unit);
1965 buf[8] = (png_byte)unit_type;
1967 png_write_complete_chunk(png_ptr, png_pHYs, buf, (png_size_t)9);
1971 #ifdef PNG_WRITE_tIME_SUPPORTED
1972 /* Write the tIME chunk. Use either png_convert_from_struct_tm()
1973 * or png_convert_from_time_t(), or fill in the structure yourself.
1976 png_write_tIME(png_structp png_ptr, png_const_timep mod_time)
1980 png_debug(1, "in png_write_tIME");
1982 if (mod_time->month > 12 || mod_time->month < 1 ||
1983 mod_time->day > 31 || mod_time->day < 1 ||
1984 mod_time->hour > 23 || mod_time->second > 60)
1986 png_warning(png_ptr, "Invalid time specified for tIME chunk");
1990 png_save_uint_16(buf, mod_time->year);
1991 buf[2] = mod_time->month;
1992 buf[3] = mod_time->day;
1993 buf[4] = mod_time->hour;
1994 buf[5] = mod_time->minute;
1995 buf[6] = mod_time->second;
1997 png_write_complete_chunk(png_ptr, png_tIME, buf, (png_size_t)7);
2001 /* Initializes the row writing capability of libpng */
2003 png_write_start_row(png_structp png_ptr)
2005 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
2006 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
2008 /* Start of interlace block */
2009 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
2011 /* Offset to next interlace block */
2012 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
2014 /* Start of interlace block in the y direction */
2015 static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
2017 /* Offset to next interlace block in the y direction */
2018 static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
2021 png_alloc_size_t buf_size;
2022 int usr_pixel_depth;
2024 png_debug(1, "in png_write_start_row");
2026 usr_pixel_depth = png_ptr->usr_channels * png_ptr->usr_bit_depth;
2027 buf_size = PNG_ROWBYTES(usr_pixel_depth, png_ptr->width) + 1;
2029 /* 1.5.6: added to allow checking in the row write code. */
2030 png_ptr->transformed_pixel_depth = png_ptr->pixel_depth;
2031 png_ptr->maximum_pixel_depth = (png_byte)usr_pixel_depth;
2033 /* Set up row buffer */
2034 png_ptr->row_buf = (png_bytep)png_malloc(png_ptr, buf_size);
2036 png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE;
2038 #ifdef PNG_WRITE_FILTER_SUPPORTED
2039 /* Set up filtering buffer, if using this filter */
2040 if (png_ptr->do_filter & PNG_FILTER_SUB)
2042 png_ptr->sub_row = (png_bytep)png_malloc(png_ptr, png_ptr->rowbytes + 1);
2044 png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
2047 /* We only need to keep the previous row if we are using one of these. */
2048 if (png_ptr->do_filter & (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH))
2050 /* Set up previous row buffer */
2051 png_ptr->prev_row = (png_bytep)png_calloc(png_ptr, buf_size);
2053 if (png_ptr->do_filter & PNG_FILTER_UP)
2055 png_ptr->up_row = (png_bytep)png_malloc(png_ptr,
2056 png_ptr->rowbytes + 1);
2058 png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;
2061 if (png_ptr->do_filter & PNG_FILTER_AVG)
2063 png_ptr->avg_row = (png_bytep)png_malloc(png_ptr,
2064 png_ptr->rowbytes + 1);
2066 png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;
2069 if (png_ptr->do_filter & PNG_FILTER_PAETH)
2071 png_ptr->paeth_row = (png_bytep)png_malloc(png_ptr,
2072 png_ptr->rowbytes + 1);
2074 png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
2077 #endif /* PNG_WRITE_FILTER_SUPPORTED */
2079 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
2080 /* If interlaced, we need to set up width and height of pass */
2081 if (png_ptr->interlaced)
2083 if (!(png_ptr->transformations & PNG_INTERLACE))
2085 png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
2086 png_pass_ystart[0]) / png_pass_yinc[0];
2088 png_ptr->usr_width = (png_ptr->width + png_pass_inc[0] - 1 -
2089 png_pass_start[0]) / png_pass_inc[0];
2094 png_ptr->num_rows = png_ptr->height;
2095 png_ptr->usr_width = png_ptr->width;
2102 png_ptr->num_rows = png_ptr->height;
2103 png_ptr->usr_width = png_ptr->width;
2106 png_zlib_claim(png_ptr, PNG_ZLIB_FOR_IDAT);
2107 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
2108 png_ptr->zstream.next_out = png_ptr->zbuf;
2111 /* Internal use only. Called when finished processing a row of data. */
2113 png_write_finish_row(png_structp png_ptr)
2115 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
2116 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
2118 /* Start of interlace block */
2119 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
2121 /* Offset to next interlace block */
2122 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
2124 /* Start of interlace block in the y direction */
2125 static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
2127 /* Offset to next interlace block in the y direction */
2128 static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
2133 png_debug(1, "in png_write_finish_row");
2136 png_ptr->row_number++;
2138 /* See if we are done */
2139 if (png_ptr->row_number < png_ptr->num_rows)
2142 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
2143 /* If interlaced, go to next pass */
2144 if (png_ptr->interlaced)
2146 png_ptr->row_number = 0;
2147 if (png_ptr->transformations & PNG_INTERLACE)
2154 /* Loop until we find a non-zero width or height pass */
2159 if (png_ptr->pass >= 7)
2162 png_ptr->usr_width = (png_ptr->width +
2163 png_pass_inc[png_ptr->pass] - 1 -
2164 png_pass_start[png_ptr->pass]) /
2165 png_pass_inc[png_ptr->pass];
2167 png_ptr->num_rows = (png_ptr->height +
2168 png_pass_yinc[png_ptr->pass] - 1 -
2169 png_pass_ystart[png_ptr->pass]) /
2170 png_pass_yinc[png_ptr->pass];
2172 if (png_ptr->transformations & PNG_INTERLACE)
2175 } while (png_ptr->usr_width == 0 || png_ptr->num_rows == 0);
2179 /* Reset the row above the image for the next pass */
2180 if (png_ptr->pass < 7)
2182 if (png_ptr->prev_row != NULL)
2183 png_memset(png_ptr->prev_row, 0,
2184 (png_size_t)(PNG_ROWBYTES(png_ptr->usr_channels*
2185 png_ptr->usr_bit_depth, png_ptr->width)) + 1);
2192 /* If we get here, we've just written the last row, so we need
2193 to flush the compressor */
2196 /* Tell the compressor we are done */
2197 ret = deflate(&png_ptr->zstream, Z_FINISH);
2199 /* Check for an error */
2202 /* Check to see if we need more room */
2203 if (!(png_ptr->zstream.avail_out))
2205 png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
2206 png_ptr->zstream.next_out = png_ptr->zbuf;
2207 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
2211 else if (ret != Z_STREAM_END)
2213 if (png_ptr->zstream.msg != NULL)
2214 png_error(png_ptr, png_ptr->zstream.msg);
2217 png_error(png_ptr, "zlib error");
2219 } while (ret != Z_STREAM_END);
2221 /* Write any extra space */
2222 if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
2224 png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size -
2225 png_ptr->zstream.avail_out);
2228 png_zlib_release(png_ptr);
2229 png_ptr->zstream.data_type = Z_BINARY;
2232 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
2233 /* Pick out the correct pixels for the interlace pass.
2234 * The basic idea here is to go through the row with a source
2235 * pointer and a destination pointer (sp and dp), and copy the
2236 * correct pixels for the pass. As the row gets compacted,
2237 * sp will always be >= dp, so we should never overwrite anything.
2238 * See the default: case for the easiest code to understand.
2241 png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
2243 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
2245 /* Start of interlace block */
2246 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
2248 /* Offset to next interlace block */
2249 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
2251 png_debug(1, "in png_do_write_interlace");
2253 /* We don't have to do anything on the last pass (6) */
2256 /* Each pixel depth is handled separately */
2257 switch (row_info->pixel_depth)
2267 png_uint_32 row_width = row_info->width;
2273 for (i = png_pass_start[pass]; i < row_width;
2274 i += png_pass_inc[pass])
2276 sp = row + (png_size_t)(i >> 3);
2277 value = (int)(*sp >> (7 - (int)(i & 0x07))) & 0x01;
2278 d |= (value << shift);
2283 *dp++ = (png_byte)d;
2305 png_uint_32 row_width = row_info->width;
2311 for (i = png_pass_start[pass]; i < row_width;
2312 i += png_pass_inc[pass])
2314 sp = row + (png_size_t)(i >> 2);
2315 value = (*sp >> ((3 - (int)(i & 0x03)) << 1)) & 0x03;
2316 d |= (value << shift);
2321 *dp++ = (png_byte)d;
2342 png_uint_32 row_width = row_info->width;
2347 for (i = png_pass_start[pass]; i < row_width;
2348 i += png_pass_inc[pass])
2350 sp = row + (png_size_t)(i >> 1);
2351 value = (*sp >> ((1 - (int)(i & 0x01)) << 2)) & 0x0f;
2352 d |= (value << shift);
2357 *dp++ = (png_byte)d;
2375 png_uint_32 row_width = row_info->width;
2376 png_size_t pixel_bytes;
2378 /* Start at the beginning */
2381 /* Find out how many bytes each pixel takes up */
2382 pixel_bytes = (row_info->pixel_depth >> 3);
2384 /* Loop through the row, only looking at the pixels that matter */
2385 for (i = png_pass_start[pass]; i < row_width;
2386 i += png_pass_inc[pass])
2388 /* Find out where the original pixel is */
2389 sp = row + (png_size_t)i * pixel_bytes;
2391 /* Move the pixel */
2393 png_memcpy(dp, sp, pixel_bytes);
2401 /* Set new row width */
2402 row_info->width = (row_info->width +
2403 png_pass_inc[pass] - 1 -
2404 png_pass_start[pass]) /
2407 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
2413 /* This filters the row, chooses which filter to use, if it has not already
2414 * been specified by the application, and then writes the row out with the
2417 static void png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row,
2418 png_size_t row_bytes);
2420 #define PNG_MAXSUM (((png_uint_32)(-1)) >> 1)
2421 #define PNG_HISHIFT 10
2422 #define PNG_LOMASK ((png_uint_32)0xffffL)
2423 #define PNG_HIMASK ((png_uint_32)(~PNG_LOMASK >> PNG_HISHIFT))
2425 png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
2428 #ifdef PNG_WRITE_FILTER_SUPPORTED
2429 png_bytep prev_row, row_buf;
2430 png_uint_32 mins, bpp;
2431 png_byte filter_to_do = png_ptr->do_filter;
2432 png_size_t row_bytes = row_info->rowbytes;
2433 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2434 int num_p_filters = png_ptr->num_prev_filters;
2437 png_debug(1, "in png_write_find_filter");
2439 #ifndef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2440 if (png_ptr->row_number == 0 && filter_to_do == PNG_ALL_FILTERS)
2442 /* These will never be selected so we need not test them. */
2443 filter_to_do &= ~(PNG_FILTER_UP | PNG_FILTER_PAETH);
2447 /* Find out how many bytes offset each pixel is */
2448 bpp = (row_info->pixel_depth + 7) >> 3;
2450 prev_row = png_ptr->prev_row;
2452 best_row = png_ptr->row_buf;
2453 #ifdef PNG_WRITE_FILTER_SUPPORTED
2457 /* The prediction method we use is to find which method provides the
2458 * smallest value when summing the absolute values of the distances
2459 * from zero, using anything >= 128 as negative numbers. This is known
2460 * as the "minimum sum of absolute differences" heuristic. Other
2461 * heuristics are the "weighted minimum sum of absolute differences"
2462 * (experimental and can in theory improve compression), and the "zlib
2463 * predictive" method (not implemented yet), which does test compressions
2464 * of lines using different filter methods, and then chooses the
2465 * (series of) filter(s) that give minimum compressed data size (VERY
2466 * computationally expensive).
2468 * GRR 980525: consider also
2470 * (1) minimum sum of absolute differences from running average (i.e.,
2471 * keep running sum of non-absolute differences & count of bytes)
2472 * [track dispersion, too? restart average if dispersion too large?]
2474 * (1b) minimum sum of absolute differences from sliding average, probably
2475 * with window size <= deflate window (usually 32K)
2477 * (2) minimum sum of squared differences from zero or running average
2478 * (i.e., ~ root-mean-square approach)
2482 /* We don't need to test the 'no filter' case if this is the only filter
2483 * that has been chosen, as it doesn't actually do anything to the data.
2485 if ((filter_to_do & PNG_FILTER_NONE) && filter_to_do != PNG_FILTER_NONE)
2488 png_uint_32 sum = 0;
2492 for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
2495 sum += (v < 128) ? v : 256 - v;
2498 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2499 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2501 png_uint_32 sumhi, sumlo;
2503 sumlo = sum & PNG_LOMASK;
2504 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; /* Gives us some footroom */
2506 /* Reduce the sum if we match any of the previous rows */
2507 for (j = 0; j < num_p_filters; j++)
2509 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
2511 sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2514 sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2519 /* Factor in the cost of this filter (this is here for completeness,
2520 * but it makes no sense to have a "cost" for the NONE filter, as
2521 * it has the minimum possible computational cost - none).
2523 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
2526 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
2529 if (sumhi > PNG_HIMASK)
2533 sum = (sumhi << PNG_HISHIFT) + sumlo;
2540 if (filter_to_do == PNG_FILTER_SUB)
2541 /* It's the only filter so no testing is needed */
2543 png_bytep rp, lp, dp;
2546 for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
2552 for (lp = row_buf + 1; i < row_bytes;
2553 i++, rp++, lp++, dp++)
2555 *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
2558 best_row = png_ptr->sub_row;
2561 else if (filter_to_do & PNG_FILTER_SUB)
2563 png_bytep rp, dp, lp;
2564 png_uint_32 sum = 0, lmins = mins;
2568 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2569 /* We temporarily increase the "minimum sum" by the factor we
2570 * would reduce the sum of this filter, so that we can do the
2571 * early exit comparison without scaling the sum each time.
2573 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2576 png_uint_32 lmhi, lmlo;
2577 lmlo = lmins & PNG_LOMASK;
2578 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2580 for (j = 0; j < num_p_filters; j++)
2582 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
2584 lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2587 lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2592 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2595 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2598 if (lmhi > PNG_HIMASK)
2602 lmins = (lmhi << PNG_HISHIFT) + lmlo;
2606 for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
2611 sum += (v < 128) ? v : 256 - v;
2614 for (lp = row_buf + 1; i < row_bytes;
2615 i++, rp++, lp++, dp++)
2617 v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
2619 sum += (v < 128) ? v : 256 - v;
2621 if (sum > lmins) /* We are already worse, don't continue. */
2625 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2626 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2629 png_uint_32 sumhi, sumlo;
2630 sumlo = sum & PNG_LOMASK;
2631 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2633 for (j = 0; j < num_p_filters; j++)
2635 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
2637 sumlo = (sumlo * png_ptr->inv_filter_weights[j]) >>
2640 sumhi = (sumhi * png_ptr->inv_filter_weights[j]) >>
2645 sumlo = (sumlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2648 sumhi = (sumhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2651 if (sumhi > PNG_HIMASK)
2655 sum = (sumhi << PNG_HISHIFT) + sumlo;
2662 best_row = png_ptr->sub_row;
2667 if (filter_to_do == PNG_FILTER_UP)
2669 png_bytep rp, dp, pp;
2672 for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
2673 pp = prev_row + 1; i < row_bytes;
2674 i++, rp++, pp++, dp++)
2676 *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
2679 best_row = png_ptr->up_row;
2682 else if (filter_to_do & PNG_FILTER_UP)
2684 png_bytep rp, dp, pp;
2685 png_uint_32 sum = 0, lmins = mins;
2690 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2691 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2694 png_uint_32 lmhi, lmlo;
2695 lmlo = lmins & PNG_LOMASK;
2696 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2698 for (j = 0; j < num_p_filters; j++)
2700 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
2702 lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2705 lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2710 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
2713 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
2716 if (lmhi > PNG_HIMASK)
2720 lmins = (lmhi << PNG_HISHIFT) + lmlo;
2724 for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
2725 pp = prev_row + 1; i < row_bytes; i++)
2727 v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2729 sum += (v < 128) ? v : 256 - v;
2731 if (sum > lmins) /* We are already worse, don't continue. */
2735 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2736 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2739 png_uint_32 sumhi, sumlo;
2740 sumlo = sum & PNG_LOMASK;
2741 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2743 for (j = 0; j < num_p_filters; j++)
2745 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
2747 sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2750 sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2755 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
2758 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
2761 if (sumhi > PNG_HIMASK)
2765 sum = (sumhi << PNG_HISHIFT) + sumlo;
2772 best_row = png_ptr->up_row;
2777 if (filter_to_do == PNG_FILTER_AVG)
2779 png_bytep rp, dp, pp, lp;
2782 for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
2783 pp = prev_row + 1; i < bpp; i++)
2785 *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
2788 for (lp = row_buf + 1; i < row_bytes; i++)
2790 *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
2793 best_row = png_ptr->avg_row;
2796 else if (filter_to_do & PNG_FILTER_AVG)
2798 png_bytep rp, dp, pp, lp;
2799 png_uint_32 sum = 0, lmins = mins;
2803 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2804 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2807 png_uint_32 lmhi, lmlo;
2808 lmlo = lmins & PNG_LOMASK;
2809 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2811 for (j = 0; j < num_p_filters; j++)
2813 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_AVG)
2815 lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2818 lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2823 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
2826 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
2829 if (lmhi > PNG_HIMASK)
2833 lmins = (lmhi << PNG_HISHIFT) + lmlo;
2837 for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
2838 pp = prev_row + 1; i < bpp; i++)
2840 v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
2842 sum += (v < 128) ? v : 256 - v;
2845 for (lp = row_buf + 1; i < row_bytes; i++)
2848 (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) & 0xff);
2850 sum += (v < 128) ? v : 256 - v;
2852 if (sum > lmins) /* We are already worse, don't continue. */
2856 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2857 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2860 png_uint_32 sumhi, sumlo;
2861 sumlo = sum & PNG_LOMASK;
2862 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2864 for (j = 0; j < num_p_filters; j++)
2866 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
2868 sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2871 sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2876 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
2879 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
2882 if (sumhi > PNG_HIMASK)
2886 sum = (sumhi << PNG_HISHIFT) + sumlo;
2893 best_row = png_ptr->avg_row;
2898 if (filter_to_do == PNG_FILTER_PAETH)
2900 png_bytep rp, dp, pp, cp, lp;
2903 for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
2904 pp = prev_row + 1; i < bpp; i++)
2906 *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2909 for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
2911 int a, b, c, pa, pb, pc, p;
2925 pa = p < 0 ? -p : p;
2926 pb = pc < 0 ? -pc : pc;
2927 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
2930 p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
2932 *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
2934 best_row = png_ptr->paeth_row;
2937 else if (filter_to_do & PNG_FILTER_PAETH)
2939 png_bytep rp, dp, pp, cp, lp;
2940 png_uint_32 sum = 0, lmins = mins;
2944 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2945 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2948 png_uint_32 lmhi, lmlo;
2949 lmlo = lmins & PNG_LOMASK;
2950 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2952 for (j = 0; j < num_p_filters; j++)
2954 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
2956 lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2959 lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2964 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2967 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2970 if (lmhi > PNG_HIMASK)
2974 lmins = (lmhi << PNG_HISHIFT) + lmlo;
2978 for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
2979 pp = prev_row + 1; i < bpp; i++)
2981 v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2983 sum += (v < 128) ? v : 256 - v;
2986 for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
2988 int a, b, c, pa, pb, pc, p;
2994 #ifndef PNG_SLOW_PAETH
3002 pa = p < 0 ? -p : p;
3003 pb = pc < 0 ? -pc : pc;
3004 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
3006 p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
3007 #else /* PNG_SLOW_PAETH */
3013 if (pa <= pb && pa <= pc)
3021 #endif /* PNG_SLOW_PAETH */
3023 v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
3025 sum += (v < 128) ? v : 256 - v;
3027 if (sum > lmins) /* We are already worse, don't continue. */
3031 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
3032 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
3035 png_uint_32 sumhi, sumlo;
3036 sumlo = sum & PNG_LOMASK;
3037 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
3039 for (j = 0; j < num_p_filters; j++)
3041 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
3043 sumlo = (sumlo * png_ptr->filter_weights[j]) >>
3046 sumhi = (sumhi * png_ptr->filter_weights[j]) >>
3051 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
3054 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
3057 if (sumhi > PNG_HIMASK)
3061 sum = (sumhi << PNG_HISHIFT) + sumlo;
3067 best_row = png_ptr->paeth_row;
3070 #endif /* PNG_WRITE_FILTER_SUPPORTED */
3072 /* Do the actual writing of the filtered row data from the chosen filter. */
3073 png_write_filtered_row(png_ptr, best_row, row_info->rowbytes+1);
3075 #ifdef PNG_WRITE_FILTER_SUPPORTED
3076 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
3077 /* Save the type of filter we picked this time for future calculations */
3078 if (png_ptr->num_prev_filters > 0)
3082 for (j = 1; j < num_p_filters; j++)
3084 png_ptr->prev_filters[j] = png_ptr->prev_filters[j - 1];
3087 png_ptr->prev_filters[j] = best_row[0];
3090 #endif /* PNG_WRITE_FILTER_SUPPORTED */
3094 /* Do the actual writing of a previously filtered row. */
3096 png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row,
3097 png_size_t avail/*includes filter byte*/)
3099 png_debug(1, "in png_write_filtered_row");
3101 png_debug1(2, "filter = %d", filtered_row[0]);
3102 /* Set up the zlib input buffer */
3104 png_ptr->zstream.next_in = filtered_row;
3105 png_ptr->zstream.avail_in = 0;
3106 /* Repeat until we have compressed all the data */
3109 int ret; /* Return of zlib */
3111 /* Record the number of bytes available - zlib supports at least 65535
3112 * bytes at one step, depending on the size of the zlib type 'uInt', the
3113 * maximum size zlib can write at once is ZLIB_IO_MAX (from pngpriv.h).
3114 * Use this because on 16 bit systems 'rowbytes' can be up to 65536 (i.e.
3115 * one more than 16 bits) and, in this case 'rowbytes+1' can overflow a
3116 * uInt. ZLIB_IO_MAX can be safely reduced to cause zlib to be called
3117 * with smaller chunks of data.
3119 if (png_ptr->zstream.avail_in == 0)
3121 if (avail > ZLIB_IO_MAX)
3123 png_ptr->zstream.avail_in = ZLIB_IO_MAX;
3124 avail -= ZLIB_IO_MAX;
3129 /* So this will fit in the available uInt space: */
3130 png_ptr->zstream.avail_in = (uInt)avail;
3135 /* Compress the data */
3136 ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
3138 /* Check for compression errors */
3141 if (png_ptr->zstream.msg != NULL)
3142 png_error(png_ptr, png_ptr->zstream.msg);
3145 png_error(png_ptr, "zlib error");
3148 /* See if it is time to write another IDAT */
3149 if (!(png_ptr->zstream.avail_out))
3151 /* Write the IDAT and reset the zlib output buffer */
3152 png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
3154 /* Repeat until all data has been compressed */
3155 } while (avail > 0 || png_ptr->zstream.avail_in > 0);
3157 /* Swap the current and previous rows */
3158 if (png_ptr->prev_row != NULL)
3162 tptr = png_ptr->prev_row;
3163 png_ptr->prev_row = png_ptr->row_buf;
3164 png_ptr->row_buf = tptr;
3167 /* Finish row - updates counters and flushes zlib if last row */
3168 png_write_finish_row(png_ptr);
3170 #ifdef PNG_WRITE_FLUSH_SUPPORTED
3171 png_ptr->flush_rows++;
3173 if (png_ptr->flush_dist > 0 &&
3174 png_ptr->flush_rows >= png_ptr->flush_dist)
3176 png_write_flush(png_ptr);
3180 #endif /* PNG_WRITE_SUPPORTED */