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 */