2 /* pngwutil.c - utilities to write a PNG file
3 *
4 * libpng 1.2.0 - September 1, 2001
5 * For conditions of distribution and use, see copyright notice in png.h
6 * Copyright (c) 1998-2001 Glenn Randers-Pehrson
7 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
8 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
9 */
11 #define PNG_INTERNAL
12 #include "png.h"
13 #ifdef PNG_WRITE_SUPPORTED
15 /* Place a 32-bit number into a buffer in PNG byte order. We work
16 * with unsigned numbers for convenience, although one supported
17 * ancillary chunk uses signed (two's complement) numbers.
18 */
19 void /* PRIVATE */
20 png_save_uint_32(png_bytep buf, png_uint_32 i)
21 {
22 buf[0] = (png_byte)((i >> 24) & 0xff);
23 buf[1] = (png_byte)((i >> 16) & 0xff);
24 buf[2] = (png_byte)((i >> 8) & 0xff);
25 buf[3] = (png_byte)(i & 0xff);
26 }
28 #if defined(PNG_WRITE_pCAL_SUPPORTED) || defined(PNG_WRITE_oFFs_SUPPORTED)
29 /* The png_save_int_32 function assumes integers are stored in two's
30 * complement format. If this isn't the case, then this routine needs to
31 * be modified to write data in two's complement format.
32 */
33 void /* PRIVATE */
34 png_save_int_32(png_bytep buf, png_int_32 i)
35 {
36 buf[0] = (png_byte)((i >> 24) & 0xff);
37 buf[1] = (png_byte)((i >> 16) & 0xff);
38 buf[2] = (png_byte)((i >> 8) & 0xff);
39 buf[3] = (png_byte)(i & 0xff);
40 }
41 #endif
43 /* Place a 16-bit number into a buffer in PNG byte order.
44 * The parameter is declared unsigned int, not png_uint_16,
45 * just to avoid potential problems on pre-ANSI C compilers.
46 */
47 void /* PRIVATE */
48 png_save_uint_16(png_bytep buf, unsigned int i)
49 {
50 buf[0] = (png_byte)((i >> 8) & 0xff);
51 buf[1] = (png_byte)(i & 0xff);
52 }
54 /* Write a PNG chunk all at once. The type is an array of ASCII characters
55 * representing the chunk name. The array must be at least 4 bytes in
56 * length, and does not need to be null terminated. To be safe, pass the
57 * pre-defined chunk names here, and if you need a new one, define it
58 * where the others are defined. The length is the length of the data.
59 * All the data must be present. If that is not possible, use the
60 * png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end()
61 * functions instead.
62 */
63 void PNGAPI
64 png_write_chunk(png_structp png_ptr, png_bytep chunk_name,
65 png_bytep data, png_size_t length)
66 {
67 png_write_chunk_start(png_ptr, chunk_name, (png_uint_32)length);
68 png_write_chunk_data(png_ptr, data, length);
69 png_write_chunk_end(png_ptr);
70 }
72 /* Write the start of a PNG chunk. The type is the chunk type.
73 * The total_length is the sum of the lengths of all the data you will be
74 * passing in png_write_chunk_data().
75 */
76 void PNGAPI
77 png_write_chunk_start(png_structp png_ptr, png_bytep chunk_name,
78 png_uint_32 length)
79 {
80 png_byte buf[4];
81 png_debug2(0, "Writing %s chunk (%lu bytes)\n", chunk_name, length);
83 /* write the length */
84 png_save_uint_32(buf, length);
85 png_write_data(png_ptr, buf, (png_size_t)4);
87 /* write the chunk name */
88 png_write_data(png_ptr, chunk_name, (png_size_t)4);
89 /* reset the crc and run it over the chunk name */
90 png_reset_crc(png_ptr);
91 png_calculate_crc(png_ptr, chunk_name, (png_size_t)4);
92 }
94 /* Write the data of a PNG chunk started with png_write_chunk_start().
95 * Note that multiple calls to this function are allowed, and that the
96 * sum of the lengths from these calls *must* add up to the total_length
97 * given to png_write_chunk_start().
98 */
99 void PNGAPI
100 png_write_chunk_data(png_structp png_ptr, png_bytep data, png_size_t length)
101 {
102 /* write the data, and run the CRC over it */
103 if (data != NULL && length > 0)
104 {
105 png_calculate_crc(png_ptr, data, length);
106 png_write_data(png_ptr, data, length);
107 }
108 }
110 /* Finish a chunk started with png_write_chunk_start(). */
111 void PNGAPI
112 png_write_chunk_end(png_structp png_ptr)
113 {
114 png_byte buf[4];
116 /* write the crc */
117 png_save_uint_32(buf, png_ptr->crc);
119 png_write_data(png_ptr, buf, (png_size_t)4);
120 }
122 /* Simple function to write the signature. If we have already written
123 * the magic bytes of the signature, or more likely, the PNG stream is
124 * being embedded into another stream and doesn't need its own signature,
125 * we should call png_set_sig_bytes() to tell libpng how many of the
126 * bytes have already been written.
127 */
128 void /* PRIVATE */
129 png_write_sig(png_structp png_ptr)
130 {
131 png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
132 /* write the rest of the 8 byte signature */
133 png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes],
134 (png_size_t)8 - png_ptr->sig_bytes);
135 if(png_ptr->sig_bytes < 3)
136 png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
137 }
139 #if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_iCCP_SUPPORTED)
140 /*
141 * This pair of functions encapsulates the operation of (a) compressing a
142 * text string, and (b) issuing it later as a series of chunk data writes.
143 * The compression_state structure is shared context for these functions
144 * set up by the caller in order to make the whole mess thread-safe.
145 */
147 typedef struct
148 {
149 char *input; /* the uncompressed input data */
150 int input_len; /* its length */
151 int num_output_ptr; /* number of output pointers used */
152 int max_output_ptr; /* size of output_ptr */
153 png_charpp output_ptr; /* array of pointers to output */
154 } compression_state;
156 /* compress given text into storage in the png_ptr structure */
157 static int /* PRIVATE */
158 png_text_compress(png_structp png_ptr,
159 png_charp text, png_size_t text_len, int compression,
160 compression_state *comp)
161 {
162 int ret;
164 comp->num_output_ptr = comp->max_output_ptr = 0;
165 comp->output_ptr = NULL;
166 comp->input = NULL;
168 /* we may just want to pass the text right through */
169 if (compression == PNG_TEXT_COMPRESSION_NONE)
170 {
171 comp->input = text;
172 comp->input_len = text_len;
173 return((int)text_len);
174 }
176 if (compression >= PNG_TEXT_COMPRESSION_LAST)
177 {
178 #if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
179 char msg[50];
180 sprintf(msg, "Unknown compression type %d", compression);
181 png_warning(png_ptr, msg);
182 #else
183 png_warning(png_ptr, "Unknown compression type");
184 #endif
185 }
187 /* We can't write the chunk until we find out how much data we have,
188 * which means we need to run the compressor first and save the
189 * output. This shouldn't be a problem, as the vast majority of
190 * comments should be reasonable, but we will set up an array of
191 * malloc'd pointers to be sure.
192 *
193 * If we knew the application was well behaved, we could simplify this
194 * greatly by assuming we can always malloc an output buffer large
195 * enough to hold the compressed text ((1001 * text_len / 1000) + 12)
196 * and malloc this directly. The only time this would be a bad idea is
197 * if we can't malloc more than 64K and we have 64K of random input
198 * data, or if the input string is incredibly large (although this
199 * wouldn't cause a failure, just a slowdown due to swapping).
200 */
202 /* set up the compression buffers */
203 png_ptr->zstream.avail_in = (uInt)text_len;
204 png_ptr->zstream.next_in = (Bytef *)text;
205 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
206 png_ptr->zstream.next_out = (Bytef *)png_ptr->zbuf;
208 /* this is the same compression loop as in png_write_row() */
209 do
210 {
211 /* compress the data */
212 ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
213 if (ret != Z_OK)
214 {
215 /* error */
216 if (png_ptr->zstream.msg != NULL)
217 png_error(png_ptr, png_ptr->zstream.msg);
218 else
219 png_error(png_ptr, "zlib error");
220 }
221 /* check to see if we need more room */
222 if (!png_ptr->zstream.avail_out && png_ptr->zstream.avail_in)
223 {
224 /* make sure the output array has room */
225 if (comp->num_output_ptr >= comp->max_output_ptr)
226 {
227 int old_max;
229 old_max = comp->max_output_ptr;
230 comp->max_output_ptr = comp->num_output_ptr + 4;
231 if (comp->output_ptr != NULL)
232 {
233 png_charpp old_ptr;
235 old_ptr = comp->output_ptr;
236 comp->output_ptr = (png_charpp)png_malloc(png_ptr,
237 (png_uint_32)(comp->max_output_ptr * sizeof (png_charpp)));
238 png_memcpy(comp->output_ptr, old_ptr, old_max
239 * sizeof (png_charp));
240 png_free(png_ptr, old_ptr);
241 }
242 else
243 comp->output_ptr = (png_charpp)png_malloc(png_ptr,
244 (png_uint_32)(comp->max_output_ptr * sizeof (png_charp)));
245 }
247 /* save the data */
248 comp->output_ptr[comp->num_output_ptr] = (png_charp)png_malloc(png_ptr,
249 (png_uint_32)png_ptr->zbuf_size);
250 png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
251 png_ptr->zbuf_size);
252 comp->num_output_ptr++;
254 /* and reset the buffer */
255 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
256 png_ptr->zstream.next_out = png_ptr->zbuf;
257 }
258 /* continue until we don't have any more to compress */
259 } while (png_ptr->zstream.avail_in);
261 /* finish the compression */
262 do
263 {
264 /* tell zlib we are finished */
265 ret = deflate(&png_ptr->zstream, Z_FINISH);
267 if (ret == Z_OK)
268 {
269 /* check to see if we need more room */
270 if (!(png_ptr->zstream.avail_out))
271 {
272 /* check to make sure our output array has room */
273 if (comp->num_output_ptr >= comp->max_output_ptr)
274 {
275 int old_max;
277 old_max = comp->max_output_ptr;
278 comp->max_output_ptr = comp->num_output_ptr + 4;
279 if (comp->output_ptr != NULL)
280 {
281 png_charpp old_ptr;
283 old_ptr = comp->output_ptr;
284 /* This could be optimized to realloc() */
285 comp->output_ptr = (png_charpp)png_malloc(png_ptr,
286 (png_uint_32)(comp->max_output_ptr * sizeof (png_charpp)));
287 png_memcpy(comp->output_ptr, old_ptr,
288 old_max * sizeof (png_charp));
289 png_free(png_ptr, old_ptr);
290 }
291 else
292 comp->output_ptr = (png_charpp)png_malloc(png_ptr,
293 (png_uint_32)(comp->max_output_ptr * sizeof (png_charp)));
294 }
296 /* save off the data */
297 comp->output_ptr[comp->num_output_ptr] =
298 (png_charp)png_malloc(png_ptr, (png_uint_32)png_ptr->zbuf_size);
299 png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
300 png_ptr->zbuf_size);
301 comp->num_output_ptr++;
303 /* and reset the buffer pointers */
304 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
305 png_ptr->zstream.next_out = png_ptr->zbuf;
306 }
307 }
308 else if (ret != Z_STREAM_END)
309 {
310 /* we got an error */
311 if (png_ptr->zstream.msg != NULL)
312 png_error(png_ptr, png_ptr->zstream.msg);
313 else
314 png_error(png_ptr, "zlib error");
315 }
316 } while (ret != Z_STREAM_END);
318 /* text length is number of buffers plus last buffer */
319 text_len = png_ptr->zbuf_size * comp->num_output_ptr;
320 if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
321 text_len += png_ptr->zbuf_size - (png_size_t)png_ptr->zstream.avail_out;
323 return((int)text_len);
324 }
326 /* ship the compressed text out via chunk writes */
327 static void /* PRIVATE */
328 png_write_compressed_data_out(png_structp png_ptr, compression_state *comp)
329 {
330 int i;
332 /* handle the no-compression case */
333 if (comp->input)
334 {
335 png_write_chunk_data(png_ptr, (png_bytep)comp->input,
336 (png_size_t)comp->input_len);
337 return;
338 }
340 /* write saved output buffers, if any */
341 for (i = 0; i < comp->num_output_ptr; i++)
342 {
343 png_write_chunk_data(png_ptr,(png_bytep)comp->output_ptr[i],
344 png_ptr->zbuf_size);
345 png_free(png_ptr, comp->output_ptr[i]);
346 comp->output_ptr[i]=NULL;
347 }
348 if (comp->max_output_ptr != 0)
349 png_free(png_ptr, comp->output_ptr);
350 comp->output_ptr=NULL;
351 /* write anything left in zbuf */
352 if (png_ptr->zstream.avail_out < (png_uint_32)png_ptr->zbuf_size)
353 png_write_chunk_data(png_ptr, png_ptr->zbuf,
354 png_ptr->zbuf_size - png_ptr->zstream.avail_out);
356 /* reset zlib for another zTXt/iTXt or the image data */
357 deflateReset(&png_ptr->zstream);
359 }
360 #endif
362 /* Write the IHDR chunk, and update the png_struct with the necessary
363 * information. Note that the rest of this code depends upon this
364 * information being correct.
365 */
366 void /* PRIVATE */
367 png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
368 int bit_depth, int color_type, int compression_type, int filter_type,
369 int interlace_type)
370 {
371 #ifdef PNG_USE_LOCAL_ARRAYS
372 PNG_IHDR;
373 #endif
374 png_byte buf[13]; /* buffer to store the IHDR info */
376 png_debug(1, "in png_write_IHDR\n");
377 /* Check that we have valid input data from the application info */
378 switch (color_type)
379 {
380 case PNG_COLOR_TYPE_GRAY:
381 switch (bit_depth)
382 {
383 case 1:
384 case 2:
385 case 4:
386 case 8:
387 case 16: png_ptr->channels = 1; break;
388 default: png_error(png_ptr,"Invalid bit depth for grayscale image");
389 }
390 break;
391 case PNG_COLOR_TYPE_RGB:
392 if (bit_depth != 8 && bit_depth != 16)
393 png_error(png_ptr, "Invalid bit depth for RGB image");
394 png_ptr->channels = 3;
395 break;
396 case PNG_COLOR_TYPE_PALETTE:
397 switch (bit_depth)
398 {
399 case 1:
400 case 2:
401 case 4:
402 case 8: png_ptr->channels = 1; break;
403 default: png_error(png_ptr, "Invalid bit depth for paletted image");
404 }
405 break;
406 case PNG_COLOR_TYPE_GRAY_ALPHA:
407 if (bit_depth != 8 && bit_depth != 16)
408 png_error(png_ptr, "Invalid bit depth for grayscale+alpha image");
409 png_ptr->channels = 2;
410 break;
411 case PNG_COLOR_TYPE_RGB_ALPHA:
412 if (bit_depth != 8 && bit_depth != 16)
413 png_error(png_ptr, "Invalid bit depth for RGBA image");
414 png_ptr->channels = 4;
415 break;
416 default:
417 png_error(png_ptr, "Invalid image color type specified");
418 }
420 if (compression_type != PNG_COMPRESSION_TYPE_BASE)
421 {
422 png_warning(png_ptr, "Invalid compression type specified");
423 compression_type = PNG_COMPRESSION_TYPE_BASE;
424 }
426 /* Write filter_method 64 (intrapixel differencing) only if
427 * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
428 * 2. Libpng did not write a PNG signature (this filter_method is only
429 * used in PNG datastreams that are embedded in MNG datastreams) and
430 * 3. The application called png_permit_mng_features with a mask that
431 * included PNG_FLAG_MNG_FILTER_64 and
432 * 4. The filter_method is 64 and
433 * 5. The color_type is RGB or RGBA
434 */
435 if (
436 #if defined(PNG_MNG_FEATURES_SUPPORTED)
437 !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
438 ((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE) == 0) &&
439 (color_type == PNG_COLOR_TYPE_RGB ||
440 color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&
441 (filter_type == PNG_INTRAPIXEL_DIFFERENCING)) &&
442 #endif
443 filter_type != PNG_FILTER_TYPE_BASE)
444 {
445 png_warning(png_ptr, "Invalid filter type specified");
446 filter_type = PNG_FILTER_TYPE_BASE;
447 }
449 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
450 if (interlace_type != PNG_INTERLACE_NONE &&
451 interlace_type != PNG_INTERLACE_ADAM7)
452 {
453 png_warning(png_ptr, "Invalid interlace type specified");
454 interlace_type = PNG_INTERLACE_ADAM7;
455 }
456 #else
457 interlace_type=PNG_INTERLACE_NONE;
458 #endif
460 /* save off the relevent information */
461 png_ptr->bit_depth = (png_byte)bit_depth;
462 png_ptr->color_type = (png_byte)color_type;
463 png_ptr->interlaced = (png_byte)interlace_type;
464 #if defined(PNG_MNG_FEATURES_SUPPORTED)
465 png_ptr->filter_type = (png_byte)filter_type;
466 #endif
467 png_ptr->width = width;
468 png_ptr->height = height;
470 png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels);
471 png_ptr->rowbytes = ((width * (png_size_t)png_ptr->pixel_depth + 7) >> 3);
472 /* set the usr info, so any transformations can modify it */
473 png_ptr->usr_width = png_ptr->width;
474 png_ptr->usr_bit_depth = png_ptr->bit_depth;
475 png_ptr->usr_channels = png_ptr->channels;
477 /* pack the header information into the buffer */
478 png_save_uint_32(buf, width);
479 png_save_uint_32(buf + 4, height);
480 buf[8] = (png_byte)bit_depth;
481 buf[9] = (png_byte)color_type;
482 buf[10] = (png_byte)compression_type;
483 buf[11] = (png_byte)filter_type;
484 buf[12] = (png_byte)interlace_type;
486 /* write the chunk */
487 png_write_chunk(png_ptr, (png_bytep)png_IHDR, buf, (png_size_t)13);
489 /* initialize zlib with PNG info */
490 png_ptr->zstream.zalloc = png_zalloc;
491 png_ptr->zstream.zfree = png_zfree;
492 png_ptr->zstream.opaque = (voidpf)png_ptr;
493 if (!(png_ptr->do_filter))
494 {
495 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
496 png_ptr->bit_depth < 8)
497 png_ptr->do_filter = PNG_FILTER_NONE;
498 else
499 png_ptr->do_filter = PNG_ALL_FILTERS;
500 }
501 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY))
502 {
503 if (png_ptr->do_filter != PNG_FILTER_NONE)
504 png_ptr->zlib_strategy = Z_FILTERED;
505 else
506 png_ptr->zlib_strategy = Z_DEFAULT_STRATEGY;
507 }
508 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_LEVEL))
509 png_ptr->zlib_level = Z_DEFAULT_COMPRESSION;
510 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL))
511 png_ptr->zlib_mem_level = 8;
512 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS))
513 png_ptr->zlib_window_bits = 15;
514 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_METHOD))
515 png_ptr->zlib_method = 8;
516 deflateInit2(&png_ptr->zstream, png_ptr->zlib_level,
517 png_ptr->zlib_method, png_ptr->zlib_window_bits,
518 png_ptr->zlib_mem_level, png_ptr->zlib_strategy);
519 png_ptr->zstream.next_out = png_ptr->zbuf;
520 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
522 png_ptr->mode = PNG_HAVE_IHDR;
523 }
525 /* write the palette. We are careful not to trust png_color to be in the
526 * correct order for PNG, so people can redefine it to any convenient
527 * structure.
528 */
529 void /* PRIVATE */
530 png_write_PLTE(png_structp png_ptr, png_colorp palette, png_uint_32 num_pal)
531 {
532 #ifdef PNG_USE_LOCAL_ARRAYS
533 PNG_PLTE;
534 #endif
535 png_uint_32 i;
536 png_colorp pal_ptr;
537 png_byte buf[3];
539 png_debug(1, "in png_write_PLTE\n");
540 if ((
541 #if defined(PNG_MNG_FEATURES_SUPPORTED)
542 !(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) &&
543 #endif
544 num_pal == 0) || num_pal > 256)
545 {
546 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
547 {
548 png_error(png_ptr, "Invalid number of colors in palette");
549 }
550 else
551 {
552 png_warning(png_ptr, "Invalid number of colors in palette");
553 return;
554 }
555 }
557 if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))
558 {
559 png_warning(png_ptr,
560 "Ignoring request to write a PLTE chunk in grayscale PNG");
561 return;
562 }
564 png_ptr->num_palette = (png_uint_16)num_pal;
565 png_debug1(3, "num_palette = %d\n", png_ptr->num_palette);
567 png_write_chunk_start(png_ptr, (png_bytep)png_PLTE, num_pal * 3);
568 #ifndef PNG_NO_POINTER_INDEXING
569 for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++)
570 {
571 buf[0] = pal_ptr->red;
572 buf[1] = pal_ptr->green;
573 buf[2] = pal_ptr->blue;
574 png_write_chunk_data(png_ptr, buf, (png_size_t)3);
575 }
576 #else
577 /* This is a little slower but some buggy compilers need to do this instead */
578 pal_ptr=palette;
579 for (i = 0; i < num_pal; i++)
580 {
581 buf[0] = pal_ptr[i].red;
582 buf[1] = pal_ptr[i].green;
583 buf[2] = pal_ptr[i].blue;
584 png_write_chunk_data(png_ptr, buf, (png_size_t)3);
585 }
586 #endif
587 png_write_chunk_end(png_ptr);
588 png_ptr->mode |= PNG_HAVE_PLTE;
589 }
591 /* write an IDAT chunk */
592 void /* PRIVATE */
593 png_write_IDAT(png_structp png_ptr, png_bytep data, png_size_t length)
594 {
595 #ifdef PNG_USE_LOCAL_ARRAYS
596 PNG_IDAT;
597 #endif
598 png_debug(1, "in png_write_IDAT\n");
599 png_write_chunk(png_ptr, (png_bytep)png_IDAT, data, length);
600 png_ptr->mode |= PNG_HAVE_IDAT;
601 }
603 /* write an IEND chunk */
604 void /* PRIVATE */
605 png_write_IEND(png_structp png_ptr)
606 {
607 #ifdef PNG_USE_LOCAL_ARRAYS
608 PNG_IEND;
609 #endif
610 png_debug(1, "in png_write_IEND\n");
611 png_write_chunk(png_ptr, (png_bytep)png_IEND, NULL, (png_size_t)0);
612 png_ptr->mode |= PNG_HAVE_IEND;
613 }
615 #if defined(PNG_WRITE_gAMA_SUPPORTED)
616 /* write a gAMA chunk */
617 #ifdef PNG_FLOATING_POINT_SUPPORTED
618 void /* PRIVATE */
619 png_write_gAMA(png_structp png_ptr, double file_gamma)
620 {
621 #ifdef PNG_USE_LOCAL_ARRAYS
622 PNG_gAMA;
623 #endif
624 png_uint_32 igamma;
625 png_byte buf[4];
627 png_debug(1, "in png_write_gAMA\n");
628 /* file_gamma is saved in 1/100,000ths */
629 igamma = (png_uint_32)(file_gamma * 100000.0 + 0.5);
630 png_save_uint_32(buf, igamma);
631 png_write_chunk(png_ptr, (png_bytep)png_gAMA, buf, (png_size_t)4);
632 }
633 #endif
634 #ifdef PNG_FIXED_POINT_SUPPORTED
635 void /* PRIVATE */
636 png_write_gAMA_fixed(png_structp png_ptr, png_fixed_point file_gamma)
637 {
638 #ifdef PNG_USE_LOCAL_ARRAYS
639 PNG_gAMA;
640 #endif
641 png_byte buf[4];
643 png_debug(1, "in png_write_gAMA\n");
644 /* file_gamma is saved in 1/100,000ths */
645 png_save_uint_32(buf, (png_uint_32)file_gamma);
646 png_write_chunk(png_ptr, (png_bytep)png_gAMA, buf, (png_size_t)4);
647 }
648 #endif
649 #endif
651 #if defined(PNG_WRITE_sRGB_SUPPORTED)
652 /* write a sRGB chunk */
653 void /* PRIVATE */
654 png_write_sRGB(png_structp png_ptr, int srgb_intent)
655 {
656 #ifdef PNG_USE_LOCAL_ARRAYS
657 PNG_sRGB;
658 #endif
659 png_byte buf[1];
661 png_debug(1, "in png_write_sRGB\n");
662 if(srgb_intent >= PNG_sRGB_INTENT_LAST)
663 png_warning(png_ptr,
664 "Invalid sRGB rendering intent specified");
665 buf[0]=(png_byte)srgb_intent;
666 png_write_chunk(png_ptr, (png_bytep)png_sRGB, buf, (png_size_t)1);
667 }
668 #endif
670 #if defined(PNG_WRITE_iCCP_SUPPORTED)
671 /* write an iCCP chunk */
672 void /* PRIVATE */
673 png_write_iCCP(png_structp png_ptr, png_charp name, int compression_type,
674 png_charp profile, int profile_len)
675 {
676 #ifdef PNG_USE_LOCAL_ARRAYS
677 PNG_iCCP;
678 #endif
679 png_size_t name_len;
680 png_charp new_name;
681 compression_state comp;
683 png_debug(1, "in png_write_iCCP\n");
684 if (name == NULL || (name_len = png_check_keyword(png_ptr, name,
685 &new_name)) == 0)
686 {
687 png_warning(png_ptr, "Empty keyword in iCCP chunk");
688 return;
689 }
691 if (compression_type != PNG_COMPRESSION_TYPE_BASE)
692 png_warning(png_ptr, "Unknown compression type in iCCP chunk");
694 if (profile == NULL)
695 profile_len = 0;
697 if (profile_len)
698 profile_len = png_text_compress(png_ptr, profile, (png_size_t)profile_len,
699 PNG_COMPRESSION_TYPE_BASE, &comp);
701 /* make sure we include the NULL after the name and the compression type */
702 png_write_chunk_start(png_ptr, (png_bytep)png_iCCP,
703 (png_uint_32)name_len+profile_len+2);
704 new_name[name_len+1]=0x00;
705 png_write_chunk_data(png_ptr, (png_bytep)new_name, name_len + 2);
707 if (profile_len)
708 png_write_compressed_data_out(png_ptr, &comp);
710 png_write_chunk_end(png_ptr);
711 png_free(png_ptr, new_name);
712 }
713 #endif
715 #if defined(PNG_WRITE_sPLT_SUPPORTED)
716 /* write a sPLT chunk */
717 void /* PRIVATE */
718 png_write_sPLT(png_structp png_ptr, png_sPLT_tp spalette)
719 {
720 #ifdef PNG_USE_LOCAL_ARRAYS
721 PNG_sPLT;
722 #endif
723 png_size_t name_len;
724 png_charp new_name;
725 png_byte entrybuf[10];
726 int entry_size = (spalette->depth == 8 ? 6 : 10);
727 int palette_size = entry_size * spalette->nentries;
728 png_sPLT_entryp ep;
729 #ifdef PNG_NO_POINTER_INDEXING
730 int i;
731 #endif
733 png_debug(1, "in png_write_sPLT\n");
734 if (spalette->name == NULL || (name_len = png_check_keyword(png_ptr,
735 spalette->name, &new_name))==0)
736 {
737 png_warning(png_ptr, "Empty keyword in sPLT chunk");
738 return;
739 }
741 /* make sure we include the NULL after the name */
742 png_write_chunk_start(png_ptr, (png_bytep)png_sPLT,
743 (png_uint_32)(name_len + 2 + palette_size));
744 png_write_chunk_data(png_ptr, (png_bytep)new_name, name_len + 1);
745 png_write_chunk_data(png_ptr, (png_bytep)&spalette->depth, 1);
747 /* loop through each palette entry, writing appropriately */
748 #ifndef PNG_NO_POINTER_INDEXING
749 for (ep = spalette->entries; ep<spalette->entries+spalette->nentries; ep++)
750 {
751 if (spalette->depth == 8)
752 {
753 entrybuf[0] = (png_byte)ep->red;
754 entrybuf[1] = (png_byte)ep->green;
755 entrybuf[2] = (png_byte)ep->blue;
756 entrybuf[3] = (png_byte)ep->alpha;
757 png_save_uint_16(entrybuf + 4, ep->frequency);
758 }
759 else
760 {
761 png_save_uint_16(entrybuf + 0, ep->red);
762 png_save_uint_16(entrybuf + 2, ep->green);
763 png_save_uint_16(entrybuf + 4, ep->blue);
764 png_save_uint_16(entrybuf + 6, ep->alpha);
765 png_save_uint_16(entrybuf + 8, ep->frequency);
766 }
767 png_write_chunk_data(png_ptr, entrybuf, (png_size_t)entry_size);
768 }
769 #else
770 ep=spalette->entries;
771 for (i=0; i>spalette->nentries; i++)
772 {
773 if (spalette->depth == 8)
774 {
775 entrybuf[0] = (png_byte)ep[i].red;
776 entrybuf[1] = (png_byte)ep[i].green;
777 entrybuf[2] = (png_byte)ep[i].blue;
778 entrybuf[3] = (png_byte)ep[i].alpha;
779 png_save_uint_16(entrybuf + 4, ep[i].frequency);
780 }
781 else
782 {
783 png_save_uint_16(entrybuf + 0, ep[i].red);
784 png_save_uint_16(entrybuf + 2, ep[i].green);
785 png_save_uint_16(entrybuf + 4, ep[i].blue);
786 png_save_uint_16(entrybuf + 6, ep[i].alpha);
787 png_save_uint_16(entrybuf + 8, ep[i].frequency);
788 }
789 png_write_chunk_data(png_ptr, entrybuf, entry_size);
790 }
791 #endif
793 png_write_chunk_end(png_ptr);
794 png_free(png_ptr, new_name);
795 }
796 #endif
798 #if defined(PNG_WRITE_sBIT_SUPPORTED)
799 /* write the sBIT chunk */
800 void /* PRIVATE */
801 png_write_sBIT(png_structp png_ptr, png_color_8p sbit, int color_type)
802 {
803 #ifdef PNG_USE_LOCAL_ARRAYS
804 PNG_sBIT;
805 #endif
806 png_byte buf[4];
807 png_size_t size;
809 png_debug(1, "in png_write_sBIT\n");
810 /* make sure we don't depend upon the order of PNG_COLOR_8 */
811 if (color_type & PNG_COLOR_MASK_COLOR)
812 {
813 png_byte maxbits;
815 maxbits = (png_byte)(color_type==PNG_COLOR_TYPE_PALETTE ? 8 :
816 png_ptr->usr_bit_depth);
817 if (sbit->red == 0 || sbit->red > maxbits ||
818 sbit->green == 0 || sbit->green > maxbits ||
819 sbit->blue == 0 || sbit->blue > maxbits)
820 {
821 png_warning(png_ptr, "Invalid sBIT depth specified");
822 return;
823 }
824 buf[0] = sbit->red;
825 buf[1] = sbit->green;
826 buf[2] = sbit->blue;
827 size = 3;
828 }
829 else
830 {
831 if (sbit->gray == 0 || sbit->gray > png_ptr->usr_bit_depth)
832 {
833 png_warning(png_ptr, "Invalid sBIT depth specified");
834 return;
835 }
836 buf[0] = sbit->gray;
837 size = 1;
838 }
840 if (color_type & PNG_COLOR_MASK_ALPHA)
841 {
842 if (sbit->alpha == 0 || sbit->alpha > png_ptr->usr_bit_depth)
843 {
844 png_warning(png_ptr, "Invalid sBIT depth specified");
845 return;
846 }
847 buf[size++] = sbit->alpha;
848 }
850 png_write_chunk(png_ptr, (png_bytep)png_sBIT, buf, size);
851 }
852 #endif
854 #if defined(PNG_WRITE_cHRM_SUPPORTED)
855 /* write the cHRM chunk */
856 #ifdef PNG_FLOATING_POINT_SUPPORTED
857 void /* PRIVATE */
858 png_write_cHRM(png_structp png_ptr, double white_x, double white_y,
859 double red_x, double red_y, double green_x, double green_y,
860 double blue_x, double blue_y)
861 {
862 #ifdef PNG_USE_LOCAL_ARRAYS
863 PNG_cHRM;
864 #endif
865 png_byte buf[32];
866 png_uint_32 itemp;
868 png_debug(1, "in png_write_cHRM\n");
869 /* each value is saved in 1/100,000ths */
870 if (white_x < 0 || white_x > 0.8 || white_y < 0 || white_y > 0.8 ||
871 white_x + white_y > 1.0)
872 {
873 png_warning(png_ptr, "Invalid cHRM white point specified");
874 #if !defined(PNG_NO_CONSOLE_IO)
875 fprintf(stderr,"white_x=%f, white_y=%f\n",white_x, white_y);
876 #endif
877 return;
878 }
879 itemp = (png_uint_32)(white_x * 100000.0 + 0.5);
880 png_save_uint_32(buf, itemp);
881 itemp = (png_uint_32)(white_y * 100000.0 + 0.5);
882 png_save_uint_32(buf + 4, itemp);
884 if (red_x < 0 || red_x > 0.8 || red_y < 0 || red_y > 0.8 ||
885 red_x + red_y > 1.0)
886 {
887 png_warning(png_ptr, "Invalid cHRM red point specified");
888 return;
889 }
890 itemp = (png_uint_32)(red_x * 100000.0 + 0.5);
891 png_save_uint_32(buf + 8, itemp);
892 itemp = (png_uint_32)(red_y * 100000.0 + 0.5);
893 png_save_uint_32(buf + 12, itemp);
895 if (green_x < 0 || green_x > 0.8 || green_y < 0 || green_y > 0.8 ||
896 green_x + green_y > 1.0)
897 {
898 png_warning(png_ptr, "Invalid cHRM green point specified");
899 return;
900 }
901 itemp = (png_uint_32)(green_x * 100000.0 + 0.5);
902 png_save_uint_32(buf + 16, itemp);
903 itemp = (png_uint_32)(green_y * 100000.0 + 0.5);
904 png_save_uint_32(buf + 20, itemp);
906 if (blue_x < 0 || blue_x > 0.8 || blue_y < 0 || blue_y > 0.8 ||
907 blue_x + blue_y > 1.0)
908 {
909 png_warning(png_ptr, "Invalid cHRM blue point specified");
910 return;
911 }
912 itemp = (png_uint_32)(blue_x * 100000.0 + 0.5);
913 png_save_uint_32(buf + 24, itemp);
914 itemp = (png_uint_32)(blue_y * 100000.0 + 0.5);
915 png_save_uint_32(buf + 28, itemp);
917 png_write_chunk(png_ptr, (png_bytep)png_cHRM, buf, (png_size_t)32);
918 }
919 #endif
920 #ifdef PNG_FIXED_POINT_SUPPORTED
921 void /* PRIVATE */
922 png_write_cHRM_fixed(png_structp png_ptr, png_fixed_point white_x,
923 png_fixed_point white_y, png_fixed_point red_x, png_fixed_point red_y,
924 png_fixed_point green_x, png_fixed_point green_y, png_fixed_point blue_x,
925 png_fixed_point blue_y)
926 {
927 #ifdef PNG_USE_LOCAL_ARRAYS
928 PNG_cHRM;
929 #endif
930 png_byte buf[32];
932 png_debug(1, "in png_write_cHRM\n");
933 /* each value is saved in 1/100,000ths */
934 if (white_x > 80000L || white_y > 80000L || white_x + white_y > 100000L)
935 {
936 png_warning(png_ptr, "Invalid fixed cHRM white point specified");
937 #if !defined(PNG_NO_CONSOLE_IO)
938 fprintf(stderr,"white_x=%ld, white_y=%ld\n",white_x, white_y);
939 #endif
940 return;
941 }
942 png_save_uint_32(buf, (png_uint_32)white_x);
943 png_save_uint_32(buf + 4, (png_uint_32)white_y);
945 if (red_x > 80000L || red_y > 80000L || red_x + red_y > 100000L)
946 {
947 png_warning(png_ptr, "Invalid cHRM fixed red point specified");
948 return;
949 }
950 png_save_uint_32(buf + 8, (png_uint_32)red_x);
951 png_save_uint_32(buf + 12, (png_uint_32)red_y);
953 if (green_x > 80000L || green_y > 80000L || green_x + green_y > 100000L)
954 {
955 png_warning(png_ptr, "Invalid fixed cHRM green point specified");
956 return;
957 }
958 png_save_uint_32(buf + 16, (png_uint_32)green_x);
959 png_save_uint_32(buf + 20, (png_uint_32)green_y);
961 if (blue_x > 80000L || blue_y > 80000L || blue_x + blue_y > 100000L)
962 {
963 png_warning(png_ptr, "Invalid fixed cHRM blue point specified");
964 return;
965 }
966 png_save_uint_32(buf + 24, (png_uint_32)blue_x);
967 png_save_uint_32(buf + 28, (png_uint_32)blue_y);
969 png_write_chunk(png_ptr, (png_bytep)png_cHRM, buf, (png_size_t)32);
970 }
971 #endif
972 #endif
974 #if defined(PNG_WRITE_tRNS_SUPPORTED)
975 /* write the tRNS chunk */
976 void /* PRIVATE */
977 png_write_tRNS(png_structp png_ptr, png_bytep trans, png_color_16p tran,
978 int num_trans, int color_type)
979 {
980 #ifdef PNG_USE_LOCAL_ARRAYS
981 PNG_tRNS;
982 #endif
983 png_byte buf[6];
985 png_debug(1, "in png_write_tRNS\n");
986 if (color_type == PNG_COLOR_TYPE_PALETTE)
987 {
988 if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette)
989 {
990 png_warning(png_ptr,"Invalid number of transparent colors specified");
991 return;
992 }
993 /* write the chunk out as it is */
994 png_write_chunk(png_ptr, (png_bytep)png_tRNS, trans, (png_size_t)num_trans);
995 }
996 else if (color_type == PNG_COLOR_TYPE_GRAY)
997 {
998 /* one 16 bit value */
999 if(tran->gray >= (1 << png_ptr->bit_depth))
1000 {
1001 png_warning(png_ptr,
1002 "Ignoring attempt to write tRNS chunk out-of-range for bit_depth");
1003 return;
1004 }
1005 png_save_uint_16(buf, tran->gray);
1006 png_write_chunk(png_ptr, (png_bytep)png_tRNS, buf, (png_size_t)2);
1007 }
1008 else if (color_type == PNG_COLOR_TYPE_RGB)
1009 {
1010 /* three 16 bit values */
1011 png_save_uint_16(buf, tran->red);
1012 png_save_uint_16(buf + 2, tran->green);
1013 png_save_uint_16(buf + 4, tran->blue);
1014 if(png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))
1015 {
1016 png_warning(png_ptr,
1017 "Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8");
1018 return;
1019 }
1020 png_write_chunk(png_ptr, (png_bytep)png_tRNS, buf, (png_size_t)6);
1021 }
1022 else
1023 {
1024 png_warning(png_ptr, "Can't write tRNS with an alpha channel");
1025 }
1026 }
1027 #endif
1029 #if defined(PNG_WRITE_bKGD_SUPPORTED)
1030 /* write the background chunk */
1031 void /* PRIVATE */
1032 png_write_bKGD(png_structp png_ptr, png_color_16p back, int color_type)
1033 {
1034 #ifdef PNG_USE_LOCAL_ARRAYS
1035 PNG_bKGD;
1036 #endif
1037 png_byte buf[6];
1039 png_debug(1, "in png_write_bKGD\n");
1040 if (color_type == PNG_COLOR_TYPE_PALETTE)
1041 {
1042 if (
1043 #if defined(PNG_MNG_FEATURES_SUPPORTED)
1044 (png_ptr->num_palette ||
1045 (!(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE))) &&
1046 #endif
1047 back->index > png_ptr->num_palette)
1048 {
1049 png_warning(png_ptr, "Invalid background palette index");
1050 return;
1051 }
1052 buf[0] = back->index;
1053 png_write_chunk(png_ptr, (png_bytep)png_bKGD, buf, (png_size_t)1);
1054 }
1055 else if (color_type & PNG_COLOR_MASK_COLOR)
1056 {
1057 png_save_uint_16(buf, back->red);
1058 png_save_uint_16(buf + 2, back->green);
1059 png_save_uint_16(buf + 4, back->blue);
1060 if(png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))
1061 {
1062 png_warning(png_ptr,
1063 "Ignoring attempt to write 16-bit bKGD chunk when bit_depth is 8");
1064 return;
1065 }
1066 png_write_chunk(png_ptr, (png_bytep)png_bKGD, buf, (png_size_t)6);
1067 }
1068 else
1069 {
1070 if(back->gray >= (1 << png_ptr->bit_depth))
1071 {
1072 png_warning(png_ptr,
1073 "Ignoring attempt to write bKGD chunk out-of-range for bit_depth");
1074 return;
1075 }
1076 png_save_uint_16(buf, back->gray);
1077 png_write_chunk(png_ptr, (png_bytep)png_bKGD, buf, (png_size_t)2);
1078 }
1079 }
1080 #endif
1082 #if defined(PNG_WRITE_hIST_SUPPORTED)
1083 /* write the histogram */
1084 void /* PRIVATE */
1085 png_write_hIST(png_structp png_ptr, png_uint_16p hist, int num_hist)
1086 {
1087 #ifdef PNG_USE_LOCAL_ARRAYS
1088 PNG_hIST;
1089 #endif
1090 int i;
1091 png_byte buf[3];
1093 png_debug(1, "in png_write_hIST\n");
1094 if (num_hist > (int)png_ptr->num_palette)
1095 {
1096 png_debug2(3, "num_hist = %d, num_palette = %d\n", num_hist,
1097 png_ptr->num_palette);
1098 png_warning(png_ptr, "Invalid number of histogram entries specified");
1099 return;
1100 }
1102 png_write_chunk_start(png_ptr, (png_bytep)png_hIST, (png_uint_32)(num_hist * 2));
1103 for (i = 0; i < num_hist; i++)
1104 {
1105 png_save_uint_16(buf, hist[i]);
1106 png_write_chunk_data(png_ptr, buf, (png_size_t)2);
1107 }
1108 png_write_chunk_end(png_ptr);
1109 }
1110 #endif
1112 #if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \
1113 defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
1114 /* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification,
1115 * and if invalid, correct the keyword rather than discarding the entire
1116 * chunk. The PNG 1.0 specification requires keywords 1-79 characters in
1117 * length, forbids leading or trailing whitespace, multiple internal spaces,
1118 * and the non-break space (0x80) from ISO 8859-1. Returns keyword length.
1119 *
1120 * The new_key is allocated to hold the corrected keyword and must be freed
1121 * by the calling routine. This avoids problems with trying to write to
1122 * static keywords without having to have duplicate copies of the strings.
1123 */
1124 png_size_t /* PRIVATE */
1125 png_check_keyword(png_structp png_ptr, png_charp key, png_charpp new_key)
1126 {
1127 png_size_t key_len;
1128 png_charp kp, dp;
1129 int kflag;
1130 int kwarn=0;
1132 png_debug(1, "in png_check_keyword\n");
1133 *new_key = NULL;
1135 if (key == NULL || (key_len = png_strlen(key)) == 0)
1136 {
1137 png_warning(png_ptr, "zero length keyword");
1138 return ((png_size_t)0);
1139 }
1141 png_debug1(2, "Keyword to be checked is '%s'\n", key);
1143 *new_key = (png_charp)png_malloc(png_ptr, (png_uint_32)(key_len + 2));
1145 /* Replace non-printing characters with a blank and print a warning */
1146 for (kp = key, dp = *new_key; *kp != '\0'; kp++, dp++)
1147 {
1148 if (*kp < 0x20 || (*kp > 0x7E && (png_byte)*kp < 0xA1))
1149 {
1150 #if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
1151 char msg[40];
1153 sprintf(msg, "invalid keyword character 0x%02X", *kp);
1154 png_warning(png_ptr, msg);
1155 #else
1156 png_warning(png_ptr, "invalid character in keyword");
1157 #endif
1158 *dp = ' ';
1159 }
1160 else
1161 {
1162 *dp = *kp;
1163 }
1164 }
1165 *dp = '\0';
1167 /* Remove any trailing white space. */
1168 kp = *new_key + key_len - 1;
1169 if (*kp == ' ')
1170 {
1171 png_warning(png_ptr, "trailing spaces removed from keyword");
1173 while (*kp == ' ')
1174 {
1175 *(kp--) = '\0';
1176 key_len--;
1177 }
1178 }
1180 /* Remove any leading white space. */
1181 kp = *new_key;
1182 if (*kp == ' ')
1183 {
1184 png_warning(png_ptr, "leading spaces removed from keyword");
1186 while (*kp == ' ')
1187 {
1188 kp++;
1189 key_len--;
1190 }
1191 }
1193 png_debug1(2, "Checking for multiple internal spaces in '%s'\n", kp);
1195 /* Remove multiple internal spaces. */
1196 for (kflag = 0, dp = *new_key; *kp != '\0'; kp++)
1197 {
1198 if (*kp == ' ' && kflag == 0)
1199 {
1200 *(dp++) = *kp;
1201 kflag = 1;
1202 }
1203 else if (*kp == ' ')
1204 {
1205 key_len--;
1206 kwarn=1;
1207 }
1208 else
1209 {
1210 *(dp++) = *kp;
1211 kflag = 0;
1212 }
1213 }
1214 *dp = '\0';
1215 if(kwarn)
1216 png_warning(png_ptr, "extra interior spaces removed from keyword");
1218 if (key_len == 0)
1219 {
1220 png_free(png_ptr, *new_key);
1221 *new_key=NULL;
1222 png_warning(png_ptr, "Zero length keyword");
1223 }
1225 if (key_len > 79)
1226 {
1227 png_warning(png_ptr, "keyword length must be 1 - 79 characters");
1228 new_key[79] = '\0';
1229 key_len = 79;
1230 }
1232 return (key_len);
1233 }
1234 #endif
1236 #if defined(PNG_WRITE_tEXt_SUPPORTED)
1237 /* write a tEXt chunk */
1238 void /* PRIVATE */
1239 png_write_tEXt(png_structp png_ptr, png_charp key, png_charp text,
1240 png_size_t text_len)
1241 {
1242 #ifdef PNG_USE_LOCAL_ARRAYS
1243 PNG_tEXt;
1244 #endif
1245 png_size_t key_len;
1246 png_charp new_key;
1248 png_debug(1, "in png_write_tEXt\n");
1249 if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0)
1250 {
1251 png_warning(png_ptr, "Empty keyword in tEXt chunk");
1252 return;
1253 }
1255 if (text == NULL || *text == '\0')
1256 text_len = 0;
1257 else
1258 text_len = png_strlen(text);
1260 /* make sure we include the 0 after the key */
1261 png_write_chunk_start(png_ptr, (png_bytep)png_tEXt, (png_uint_32)key_len+text_len+1);
1262 /*
1263 * We leave it to the application to meet PNG-1.0 requirements on the
1264 * contents of the text. PNG-1.0 through PNG-1.2 discourage the use of
1265 * any non-Latin-1 characters except for NEWLINE. ISO PNG will forbid them.
1266 * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1267 */
1268 png_write_chunk_data(png_ptr, (png_bytep)new_key, key_len + 1);
1269 if (text_len)
1270 png_write_chunk_data(png_ptr, (png_bytep)text, text_len);
1272 png_write_chunk_end(png_ptr);
1273 png_free(png_ptr, new_key);
1274 }
1275 #endif
1277 #if defined(PNG_WRITE_zTXt_SUPPORTED)
1278 /* write a compressed text chunk */
1279 void /* PRIVATE */
1280 png_write_zTXt(png_structp png_ptr, png_charp key, png_charp text,
1281 png_size_t text_len, int compression)
1282 {
1283 #ifdef PNG_USE_LOCAL_ARRAYS
1284 PNG_zTXt;
1285 #endif
1286 png_size_t key_len;
1287 char buf[1];
1288 png_charp new_key;
1289 compression_state comp;
1291 png_debug(1, "in png_write_zTXt\n");
1293 if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0)
1294 {
1295 png_warning(png_ptr, "Empty keyword in zTXt chunk");
1296 return;
1297 }
1299 if (text == NULL || *text == '\0' || compression==PNG_TEXT_COMPRESSION_NONE)
1300 {
1301 png_write_tEXt(png_ptr, new_key, text, (png_size_t)0);
1302 png_free(png_ptr, new_key);
1303 return;
1304 }
1306 text_len = png_strlen(text);
1308 png_free(png_ptr, new_key);
1310 /* compute the compressed data; do it now for the length */
1311 text_len = png_text_compress(png_ptr, text, text_len, compression,
1312 &comp);
1314 /* write start of chunk */
1315 png_write_chunk_start(png_ptr, (png_bytep)png_zTXt, (png_uint_32)
1316 (key_len+text_len+2));
1317 /* write key */
1318 png_write_chunk_data(png_ptr, (png_bytep)key, key_len + 1);
1319 buf[0] = (png_byte)compression;
1320 /* write compression */
1321 png_write_chunk_data(png_ptr, (png_bytep)buf, (png_size_t)1);
1322 /* write the compressed data */
1323 png_write_compressed_data_out(png_ptr, &comp);
1325 /* close the chunk */
1326 png_write_chunk_end(png_ptr);
1327 }
1328 #endif
1330 #if defined(PNG_WRITE_iTXt_SUPPORTED)
1331 /* write an iTXt chunk */
1332 void /* PRIVATE */
1333 png_write_iTXt(png_structp png_ptr, int compression, png_charp key,
1334 png_charp lang, png_charp lang_key, png_charp text)
1335 {
1336 #ifdef PNG_USE_LOCAL_ARRAYS
1337 PNG_iTXt;
1338 #endif
1339 png_size_t lang_len, key_len, lang_key_len, text_len;
1340 png_charp new_lang, new_key;
1341 png_byte cbuf[2];
1342 compression_state comp;
1344 png_debug(1, "in png_write_iTXt\n");
1346 if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0)
1347 {
1348 png_warning(png_ptr, "Empty keyword in iTXt chunk");
1349 return;
1350 }
1351 if (lang == NULL || (lang_len = png_check_keyword(png_ptr, lang,
1352 &new_lang))==0)
1353 {
1354 png_warning(png_ptr, "Empty language field in iTXt chunk");
1355 return;
1356 }
1357 lang_key_len = png_strlen(lang_key);
1358 text_len = png_strlen(text);
1360 if (text == NULL || *text == '\0')
1361 text_len = 0;
1363 /* compute the compressed data; do it now for the length */
1364 text_len = png_text_compress(png_ptr, text, text_len, compression-2,
1365 &comp);
1367 /* make sure we include the compression flag, the compression byte,
1368 * and the NULs after the key, lang, and lang_key parts */
1370 png_write_chunk_start(png_ptr, (png_bytep)png_iTXt,
1371 (png_uint_32)(
1372 5 /* comp byte, comp flag, terminators for key, lang and lang_key */
1373 + key_len
1374 + lang_len
1375 + lang_key_len
1376 + text_len));
1378 /*
1379 * We leave it to the application to meet PNG-1.0 requirements on the
1380 * contents of the text. PNG-1.0 through PNG-1.2 discourage the use of
1381 * any non-Latin-1 characters except for NEWLINE. ISO PNG will forbid them.
1382 * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1383 */
1384 png_write_chunk_data(png_ptr, (png_bytep)new_key, key_len + 1);
1386 /* set the compression flag */
1387 if (compression == PNG_ITXT_COMPRESSION_NONE || \
1388 compression == PNG_TEXT_COMPRESSION_NONE)
1389 cbuf[0] = 0;
1390 else /* compression == PNG_ITXT_COMPRESSION_zTXt */
1391 cbuf[0] = 1;
1392 /* set the compression method */
1393 cbuf[1] = 0;
1394 png_write_chunk_data(png_ptr, cbuf, 2);
1396 png_write_chunk_data(png_ptr, (png_bytep)new_lang, lang_len + 1);
1397 png_write_chunk_data(png_ptr, (png_bytep)lang_key, lang_key_len+1);
1398 png_write_chunk_data(png_ptr, '\0', 1);
1400 png_write_compressed_data_out(png_ptr, &comp);
1402 png_write_chunk_end(png_ptr);
1403 png_free(png_ptr, new_key);
1404 png_free(png_ptr, new_lang);
1405 }
1406 #endif
1408 #if defined(PNG_WRITE_oFFs_SUPPORTED)
1409 /* write the oFFs chunk */
1410 void /* PRIVATE */
1411 png_write_oFFs(png_structp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
1412 int unit_type)
1413 {
1414 #ifdef PNG_USE_LOCAL_ARRAYS
1415 PNG_oFFs;
1416 #endif
1417 png_byte buf[9];
1419 png_debug(1, "in png_write_oFFs\n");
1420 if (unit_type >= PNG_OFFSET_LAST)
1421 png_warning(png_ptr, "Unrecognized unit type for oFFs chunk");
1423 png_save_int_32(buf, x_offset);
1424 png_save_int_32(buf + 4, y_offset);
1425 buf[8] = (png_byte)unit_type;
1427 png_write_chunk(png_ptr, (png_bytep)png_oFFs, buf, (png_size_t)9);
1428 }
1429 #endif
1431 #if defined(PNG_WRITE_pCAL_SUPPORTED)
1432 /* write the pCAL chunk (described in the PNG extensions document) */
1433 void /* PRIVATE */
1434 png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
1435 png_int_32 X1, int type, int nparams, png_charp units, png_charpp params)
1436 {
1437 #ifdef PNG_USE_LOCAL_ARRAYS
1438 PNG_pCAL;
1439 #endif
1440 png_size_t purpose_len, units_len, total_len;
1441 png_uint_32p params_len;
1442 png_byte buf[10];
1443 png_charp new_purpose;
1444 int i;
1446 png_debug1(1, "in png_write_pCAL (%d parameters)\n", nparams);
1447 if (type >= PNG_EQUATION_LAST)
1448 png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");
1450 purpose_len = png_check_keyword(png_ptr, purpose, &new_purpose) + 1;
1451 png_debug1(3, "pCAL purpose length = %d\n", (int)purpose_len);
1452 units_len = png_strlen(units) + (nparams == 0 ? 0 : 1);
1453 png_debug1(3, "pCAL units length = %d\n", (int)units_len);
1454 total_len = purpose_len + units_len + 10;
1456 params_len = (png_uint_32p)png_malloc(png_ptr, (png_uint_32)(nparams
1457 *sizeof(png_uint_32)));
1459 /* Find the length of each parameter, making sure we don't count the
1460 null terminator for the last parameter. */
1461 for (i = 0; i < nparams; i++)
1462 {
1463 params_len[i] = png_strlen(params[i]) + (i == nparams - 1 ? 0 : 1);
1464 png_debug2(3, "pCAL parameter %d length = %lu\n", i, params_len[i]);
1465 total_len += (png_size_t)params_len[i];
1466 }
1468 png_debug1(3, "pCAL total length = %d\n", (int)total_len);
1469 png_write_chunk_start(png_ptr, (png_bytep)png_pCAL, (png_uint_32)total_len);
1470 png_write_chunk_data(png_ptr, (png_bytep)new_purpose, purpose_len);
1471 png_save_int_32(buf, X0);
1472 png_save_int_32(buf + 4, X1);
1473 buf[8] = (png_byte)type;
1474 buf[9] = (png_byte)nparams;
1475 png_write_chunk_data(png_ptr, buf, (png_size_t)10);
1476 png_write_chunk_data(png_ptr, (png_bytep)units, (png_size_t)units_len);
1478 png_free(png_ptr, new_purpose);
1480 for (i = 0; i < nparams; i++)
1481 {
1482 png_write_chunk_data(png_ptr, (png_bytep)params[i],
1483 (png_size_t)params_len[i]);
1484 }
1486 png_free(png_ptr, params_len);
1487 png_write_chunk_end(png_ptr);
1488 }
1489 #endif
1491 #if defined(PNG_WRITE_sCAL_SUPPORTED)
1492 /* write the sCAL chunk */
1493 #if defined(PNG_FLOATING_POINT_SUPPORTED) && !defined(PNG_NO_STDIO)
1494 void /* PRIVATE */
1495 png_write_sCAL(png_structp png_ptr, int unit, double width,double height)
1496 {
1497 #ifdef PNG_USE_LOCAL_ARRAYS
1498 PNG_sCAL;
1499 #endif
1500 png_size_t total_len;
1501 char wbuf[32], hbuf[32];
1503 png_debug(1, "in png_write_sCAL\n");
1505 #if defined(_WIN32_WCE)
1506 /* sprintf() function is not supported on WindowsCE */
1507 {
1508 wchar_t wc_buf[32];
1509 swprintf(wc_buf, TEXT("%12.12e"), width);
1510 WideCharToMultiByte(CP_ACP, 0, wc_buf, -1, wbuf, 32, NULL, NULL);
1511 swprintf(wc_buf, TEXT("%12.12e"), height);
1512 WideCharToMultiByte(CP_ACP, 0, wc_buf, -1, hbuf, 32, NULL, NULL);
1513 }
1514 #else
1515 sprintf(wbuf, "%12.12e", width);
1516 sprintf(hbuf, "%12.12e", height);
1517 #endif
1518 total_len = 1 + png_strlen(wbuf)+1 + png_strlen(hbuf);
1520 png_debug1(3, "sCAL total length = %d\n", (int)total_len);
1521 png_write_chunk_start(png_ptr, (png_bytep)png_sCAL, (png_uint_32)total_len);
1522 png_write_chunk_data(png_ptr, (png_bytep)&unit, 1);
1523 png_write_chunk_data(png_ptr, (png_bytep)wbuf, png_strlen(wbuf)+1);
1524 png_write_chunk_data(png_ptr, (png_bytep)hbuf, png_strlen(hbuf));
1526 png_write_chunk_end(png_ptr);
1527 }
1528 #else
1529 #ifdef PNG_FIXED_POINT_SUPPORTED
1530 void /* PRIVATE */
1531 png_write_sCAL_s(png_structp png_ptr, int unit, png_charp width,
1532 png_charp height)
1533 {
1534 #ifdef PNG_USE_LOCAL_ARRAYS
1535 PNG_sCAL;
1536 #endif
1537 png_size_t total_len;
1538 char wbuf[32], hbuf[32];
1540 png_debug(1, "in png_write_sCAL_s\n");
1542 png_strcpy(wbuf,(const char *)width);
1543 png_strcpy(hbuf,(const char *)height);
1544 total_len = 1 + png_strlen(wbuf)+1 + png_strlen(hbuf);
1546 png_debug1(3, "sCAL total length = %d\n", total_len);
1547 png_write_chunk_start(png_ptr, (png_bytep)png_sCAL, (png_uint_32)total_len);
1548 png_write_chunk_data(png_ptr, (png_bytep)&unit, 1);
1549 png_write_chunk_data(png_ptr, (png_bytep)wbuf, png_strlen(wbuf)+1);
1550 png_write_chunk_data(png_ptr, (png_bytep)hbuf, png_strlen(hbuf));
1552 png_write_chunk_end(png_ptr);
1553 }
1554 #endif
1555 #endif
1556 #endif
1558 #if defined(PNG_WRITE_pHYs_SUPPORTED)
1559 /* write the pHYs chunk */
1560 void /* PRIVATE */
1561 png_write_pHYs(png_structp png_ptr, png_uint_32 x_pixels_per_unit,
1562 png_uint_32 y_pixels_per_unit,
1563 int unit_type)
1564 {
1565 #ifdef PNG_USE_LOCAL_ARRAYS
1566 PNG_pHYs;
1567 #endif
1568 png_byte buf[9];
1570 png_debug(1, "in png_write_pHYs\n");
1571 if (unit_type >= PNG_RESOLUTION_LAST)
1572 png_warning(png_ptr, "Unrecognized unit type for pHYs chunk");
1574 png_save_uint_32(buf, x_pixels_per_unit);
1575 png_save_uint_32(buf + 4, y_pixels_per_unit);
1576 buf[8] = (png_byte)unit_type;
1578 png_write_chunk(png_ptr, (png_bytep)png_pHYs, buf, (png_size_t)9);
1579 }
1580 #endif
1582 #if defined(PNG_WRITE_tIME_SUPPORTED)
1583 /* Write the tIME chunk. Use either png_convert_from_struct_tm()
1584 * or png_convert_from_time_t(), or fill in the structure yourself.
1585 */
1586 void /* PRIVATE */
1587 png_write_tIME(png_structp png_ptr, png_timep mod_time)
1588 {
1589 #ifdef PNG_USE_LOCAL_ARRAYS
1590 PNG_tIME;
1591 #endif
1592 png_byte buf[7];
1594 png_debug(1, "in png_write_tIME\n");
1595 if (mod_time->month > 12 || mod_time->month < 1 ||
1596 mod_time->day > 31 || mod_time->day < 1 ||
1597 mod_time->hour > 23 || mod_time->second > 60)
1598 {
1599 png_warning(png_ptr, "Invalid time specified for tIME chunk");
1600 return;
1601 }
1603 png_save_uint_16(buf, mod_time->year);
1604 buf[2] = mod_time->month;
1605 buf[3] = mod_time->day;
1606 buf[4] = mod_time->hour;
1607 buf[5] = mod_time->minute;
1608 buf[6] = mod_time->second;
1610 png_write_chunk(png_ptr, (png_bytep)png_tIME, buf, (png_size_t)7);
1611 }
1612 #endif
1614 /* initializes the row writing capability of libpng */
1615 void /* PRIVATE */
1616 png_write_start_row(png_structp png_ptr)
1617 {
1618 #ifdef PNG_USE_LOCAL_ARRAYS
1619 /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1621 /* start of interlace block */
1622 int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
1624 /* offset to next interlace block */
1625 int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
1627 /* start of interlace block in the y direction */
1628 int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
1630 /* offset to next interlace block in the y direction */
1631 int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
1632 #endif
1634 png_size_t buf_size;
1636 png_debug(1, "in png_write_start_row\n");
1637 buf_size = (png_size_t)(((png_ptr->width * png_ptr->usr_channels *
1638 png_ptr->usr_bit_depth + 7) >> 3) + 1);
1640 /* set up row buffer */
1641 png_ptr->row_buf = (png_bytep)png_malloc(png_ptr, (png_uint_32)buf_size);
1642 png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE;
1644 /* set up filtering buffer, if using this filter */
1645 if (png_ptr->do_filter & PNG_FILTER_SUB)
1646 {
1647 png_ptr->sub_row = (png_bytep)png_malloc(png_ptr,
1648 (png_ptr->rowbytes + 1));
1649 png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
1650 }
1652 /* We only need to keep the previous row if we are using one of these. */
1653 if (png_ptr->do_filter & (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH))
1654 {
1655 /* set up previous row buffer */
1656 png_ptr->prev_row = (png_bytep)png_malloc(png_ptr, (png_uint_32)buf_size);
1657 png_memset(png_ptr->prev_row, 0, buf_size);
1659 if (png_ptr->do_filter & PNG_FILTER_UP)
1660 {
1661 png_ptr->up_row = (png_bytep )png_malloc(png_ptr,
1662 (png_ptr->rowbytes + 1));
1663 png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;
1664 }
1666 if (png_ptr->do_filter & PNG_FILTER_AVG)
1667 {
1668 png_ptr->avg_row = (png_bytep)png_malloc(png_ptr,
1669 (png_ptr->rowbytes + 1));
1670 png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;
1671 }
1673 if (png_ptr->do_filter & PNG_FILTER_PAETH)
1674 {
1675 png_ptr->paeth_row = (png_bytep )png_malloc(png_ptr,
1676 (png_ptr->rowbytes + 1));
1677 png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
1678 }
1679 }
1681 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
1682 /* if interlaced, we need to set up width and height of pass */
1683 if (png_ptr->interlaced)
1684 {
1685 if (!(png_ptr->transformations & PNG_INTERLACE))
1686 {
1687 png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
1688 png_pass_ystart[0]) / png_pass_yinc[0];
1689 png_ptr->usr_width = (png_ptr->width + png_pass_inc[0] - 1 -
1690 png_pass_start[0]) / png_pass_inc[0];
1691 }
1692 else
1693 {
1694 png_ptr->num_rows = png_ptr->height;
1695 png_ptr->usr_width = png_ptr->width;
1696 }
1697 }
1698 else
1699 #endif
1700 {
1701 png_ptr->num_rows = png_ptr->height;
1702 png_ptr->usr_width = png_ptr->width;
1703 }
1704 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1705 png_ptr->zstream.next_out = png_ptr->zbuf;
1706 }
1708 /* Internal use only. Called when finished processing a row of data. */
1709 void /* PRIVATE */
1710 png_write_finish_row(png_structp png_ptr)
1711 {
1712 #ifdef PNG_USE_LOCAL_ARRAYS
1713 /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1715 /* start of interlace block */
1716 int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
1718 /* offset to next interlace block */
1719 int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
1721 /* start of interlace block in the y direction */
1722 int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
1724 /* offset to next interlace block in the y direction */
1725 int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
1726 #endif
1728 int ret;
1730 png_debug(1, "in png_write_finish_row\n");
1731 /* next row */
1732 png_ptr->row_number++;
1734 /* see if we are done */
1735 if (png_ptr->row_number < png_ptr->num_rows)
1736 return;
1738 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
1739 /* if interlaced, go to next pass */
1740 if (png_ptr->interlaced)
1741 {
1742 png_ptr->row_number = 0;
1743 if (png_ptr->transformations & PNG_INTERLACE)
1744 {
1745 png_ptr->pass++;
1746 }
1747 else
1748 {
1749 /* loop until we find a non-zero width or height pass */
1750 do
1751 {
1752 png_ptr->pass++;
1753 if (png_ptr->pass >= 7)
1754 break;
1755 png_ptr->usr_width = (png_ptr->width +
1756 png_pass_inc[png_ptr->pass] - 1 -
1757 png_pass_start[png_ptr->pass]) /
1758 png_pass_inc[png_ptr->pass];
1759 png_ptr->num_rows = (png_ptr->height +
1760 png_pass_yinc[png_ptr->pass] - 1 -
1761 png_pass_ystart[png_ptr->pass]) /
1762 png_pass_yinc[png_ptr->pass];
1763 if (png_ptr->transformations & PNG_INTERLACE)
1764 break;
1765 } while (png_ptr->usr_width == 0 || png_ptr->num_rows == 0);
1767 }
1769 /* reset the row above the image for the next pass */
1770 if (png_ptr->pass < 7)
1771 {
1772 if (png_ptr->prev_row != NULL)
1773 png_memset(png_ptr->prev_row, 0,
1774 (png_size_t) (((png_uint_32)png_ptr->usr_channels *
1775 (png_uint_32)png_ptr->usr_bit_depth *
1776 png_ptr->width + 7) >> 3) + 1);
1777 return;
1778 }
1779 }
1780 #endif
1782 /* if we get here, we've just written the last row, so we need
1783 to flush the compressor */
1784 do
1785 {
1786 /* tell the compressor we are done */
1787 ret = deflate(&png_ptr->zstream, Z_FINISH);
1788 /* check for an error */
1789 if (ret == Z_OK)
1790 {
1791 /* check to see if we need more room */
1792 if (!(png_ptr->zstream.avail_out))
1793 {
1794 png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
1795 png_ptr->zstream.next_out = png_ptr->zbuf;
1796 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1797 }
1798 }
1799 else if (ret != Z_STREAM_END)
1800 {
1801 if (png_ptr->zstream.msg != NULL)
1802 png_error(png_ptr, png_ptr->zstream.msg);
1803 else
1804 png_error(png_ptr, "zlib error");
1805 }
1806 } while (ret != Z_STREAM_END);
1808 /* write any extra space */
1809 if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
1810 {
1811 png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size -
1812 png_ptr->zstream.avail_out);
1813 }
1815 deflateReset(&png_ptr->zstream);
1816 }
1818 #if defined(PNG_WRITE_INTERLACING_SUPPORTED)
1819 /* Pick out the correct pixels for the interlace pass.
1820 * The basic idea here is to go through the row with a source
1821 * pointer and a destination pointer (sp and dp), and copy the
1822 * correct pixels for the pass. As the row gets compacted,
1823 * sp will always be >= dp, so we should never overwrite anything.
1824 * See the default: case for the easiest code to understand.
1825 */
1826 void /* PRIVATE */
1827 png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
1828 {
1829 #ifdef PNG_USE_LOCAL_ARRAYS
1830 /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1832 /* start of interlace block */
1833 int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
1835 /* offset to next interlace block */
1836 int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
1837 #endif
1839 png_debug(1, "in png_do_write_interlace\n");
1840 /* we don't have to do anything on the last pass (6) */
1841 #if defined(PNG_USELESS_TESTS_SUPPORTED)
1842 if (row != NULL && row_info != NULL && pass < 6)
1843 #else
1844 if (pass < 6)
1845 #endif
1846 {
1847 /* each pixel depth is handled separately */
1848 switch (row_info->pixel_depth)
1849 {
1850 case 1:
1851 {
1852 png_bytep sp;
1853 png_bytep dp;
1854 int shift;
1855 int d;
1856 int value;
1857 png_uint_32 i;
1858 png_uint_32 row_width = row_info->width;
1860 dp = row;
1861 d = 0;
1862 shift = 7;
1863 for (i = png_pass_start[pass]; i < row_width;
1864 i += png_pass_inc[pass])
1865 {
1866 sp = row + (png_size_t)(i >> 3);
1867 value = (int)(*sp >> (7 - (int)(i & 0x07))) & 0x01;
1868 d |= (value << shift);
1870 if (shift == 0)
1871 {
1872 shift = 7;
1873 *dp++ = (png_byte)d;
1874 d = 0;
1875 }
1876 else
1877 shift--;
1879 }
1880 if (shift != 7)
1881 *dp = (png_byte)d;
1882 break;
1883 }
1884 case 2:
1885 {
1886 png_bytep sp;
1887 png_bytep dp;
1888 int shift;
1889 int d;
1890 int value;
1891 png_uint_32 i;
1892 png_uint_32 row_width = row_info->width;
1894 dp = row;
1895 shift = 6;
1896 d = 0;
1897 for (i = png_pass_start[pass]; i < row_width;
1898 i += png_pass_inc[pass])
1899 {
1900 sp = row + (png_size_t)(i >> 2);
1901 value = (*sp >> ((3 - (int)(i & 0x03)) << 1)) & 0x03;
1902 d |= (value << shift);
1904 if (shift == 0)
1905 {
1906 shift = 6;
1907 *dp++ = (png_byte)d;
1908 d = 0;
1909 }
1910 else
1911 shift -= 2;
1912 }
1913 if (shift != 6)
1914 *dp = (png_byte)d;
1915 break;
1916 }
1917 case 4:
1918 {
1919 png_bytep sp;
1920 png_bytep dp;
1921 int shift;
1922 int d;
1923 int value;
1924 png_uint_32 i;
1925 png_uint_32 row_width = row_info->width;
1927 dp = row;
1928 shift = 4;
1929 d = 0;
1930 for (i = png_pass_start[pass]; i < row_width;
1931 i += png_pass_inc[pass])
1932 {
1933 sp = row + (png_size_t)(i >> 1);
1934 value = (*sp >> ((1 - (int)(i & 0x01)) << 2)) & 0x0f;
1935 d |= (value << shift);
1937 if (shift == 0)
1938 {
1939 shift = 4;
1940 *dp++ = (png_byte)d;
1941 d = 0;
1942 }
1943 else
1944 shift -= 4;
1945 }
1946 if (shift != 4)
1947 *dp = (png_byte)d;
1948 break;
1949 }
1950 default:
1951 {
1952 png_bytep sp;
1953 png_bytep dp;
1954 png_uint_32 i;
1955 png_uint_32 row_width = row_info->width;
1956 png_size_t pixel_bytes;
1958 /* start at the beginning */
1959 dp = row;
1960 /* find out how many bytes each pixel takes up */
1961 pixel_bytes = (row_info->pixel_depth >> 3);
1962 /* loop through the row, only looking at the pixels that
1963 matter */
1964 for (i = png_pass_start[pass]; i < row_width;
1965 i += png_pass_inc[pass])
1966 {
1967 /* find out where the original pixel is */
1968 sp = row + (png_size_t)i * pixel_bytes;
1969 /* move the pixel */
1970 if (dp != sp)
1971 png_memcpy(dp, sp, pixel_bytes);
1972 /* next pixel */
1973 dp += pixel_bytes;
1974 }
1975 break;
1976 }
1977 }
1978 /* set new row width */
1979 row_info->width = (row_info->width +
1980 png_pass_inc[pass] - 1 -
1981 png_pass_start[pass]) /
1982 png_pass_inc[pass];
1983 row_info->rowbytes = ((row_info->width *
1984 row_info->pixel_depth + 7) >> 3);
1985 }
1986 }
1987 #endif
1989 /* This filters the row, chooses which filter to use, if it has not already
1990 * been specified by the application, and then writes the row out with the
1991 * chosen filter.
1992 */
1993 #define PNG_MAXSUM (~((png_uint_32)0) >> 1)
1994 #define PNG_HISHIFT 10
1995 #define PNG_LOMASK ((png_uint_32)0xffffL)
1996 #define PNG_HIMASK ((png_uint_32)(~PNG_LOMASK >> PNG_HISHIFT))
1997 void /* PRIVATE */
1998 png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
1999 {
2000 png_bytep prev_row, best_row, row_buf;
2001 png_uint_32 mins, bpp;
2002 png_byte filter_to_do = png_ptr->do_filter;
2003 png_uint_32 row_bytes = row_info->rowbytes;
2004 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2005 int num_p_filters = (int)png_ptr->num_prev_filters;
2006 #endif
2008 png_debug(1, "in png_write_find_filter\n");
2009 /* find out how many bytes offset each pixel is */
2010 bpp = (row_info->pixel_depth + 7) / 8;
2012 prev_row = png_ptr->prev_row;
2013 best_row = row_buf = png_ptr->row_buf;
2014 mins = PNG_MAXSUM;
2016 /* The prediction method we use is to find which method provides the
2017 * smallest value when summing the absolute values of the distances
2018 * from zero, using anything >= 128 as negative numbers. This is known
2019 * as the "minimum sum of absolute differences" heuristic. Other
2020 * heuristics are the "weighted minimum sum of absolute differences"
2021 * (experimental and can in theory improve compression), and the "zlib
2022 * predictive" method (not implemented yet), which does test compressions
2023 * of lines using different filter methods, and then chooses the
2024 * (series of) filter(s) that give minimum compressed data size (VERY
2025 * computationally expensive).
2026 *
2027 * GRR 980525: consider also
2028 * (1) minimum sum of absolute differences from running average (i.e.,
2029 * keep running sum of non-absolute differences & count of bytes)
2030 * [track dispersion, too? restart average if dispersion too large?]
2031 * (1b) minimum sum of absolute differences from sliding average, probably
2032 * with window size <= deflate window (usually 32K)
2033 * (2) minimum sum of squared differences from zero or running average
2034 * (i.e., ~ root-mean-square approach)
2035 */
2038 /* We don't need to test the 'no filter' case if this is the only filter
2039 * that has been chosen, as it doesn't actually do anything to the data.
2040 */
2041 if ((filter_to_do & PNG_FILTER_NONE) &&
2042 filter_to_do != PNG_FILTER_NONE)
2043 {
2044 png_bytep rp;
2045 png_uint_32 sum = 0;
2046 png_uint_32 i;
2047 int v;
2049 for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
2050 {
2051 v = *rp;
2052 sum += (v < 128) ? v : 256 - v;
2053 }
2055 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2056 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2057 {
2058 png_uint_32 sumhi, sumlo;
2059 int j;
2060 sumlo = sum & PNG_LOMASK;
2061 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; /* Gives us some footroom */
2063 /* Reduce the sum if we match any of the previous rows */
2064 for (j = 0; j < num_p_filters; j++)
2065 {
2066 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
2067 {
2068 sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2069 PNG_WEIGHT_SHIFT;
2070 sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2071 PNG_WEIGHT_SHIFT;
2072 }
2073 }
2075 /* Factor in the cost of this filter (this is here for completeness,
2076 * but it makes no sense to have a "cost" for the NONE filter, as
2077 * it has the minimum possible computational cost - none).
2078 */
2079 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
2080 PNG_COST_SHIFT;
2081 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
2082 PNG_COST_SHIFT;
2084 if (sumhi > PNG_HIMASK)
2085 sum = PNG_MAXSUM;
2086 else
2087 sum = (sumhi << PNG_HISHIFT) + sumlo;
2088 }
2089 #endif
2090 mins = sum;
2091 }
2093 /* sub filter */
2094 if (filter_to_do == PNG_FILTER_SUB)
2095 /* it's the only filter so no testing is needed */
2096 {
2097 png_bytep rp, lp, dp;
2098 png_uint_32 i;
2099 for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
2100 i++, rp++, dp++)
2101 {
2102 *dp = *rp;
2103 }
2104 for (lp = row_buf + 1; i < row_bytes;
2105 i++, rp++, lp++, dp++)
2106 {
2107 *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
2108 }
2109 best_row = png_ptr->sub_row;
2110 }
2112 else if (filter_to_do & PNG_FILTER_SUB)
2113 {
2114 png_bytep rp, dp, lp;
2115 png_uint_32 sum = 0, lmins = mins;
2116 png_uint_32 i;
2117 int v;
2119 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2120 /* We temporarily increase the "minimum sum" by the factor we
2121 * would reduce the sum of this filter, so that we can do the
2122 * early exit comparison without scaling the sum each time.
2123 */
2124 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2125 {
2126 int j;
2127 png_uint_32 lmhi, lmlo;
2128 lmlo = lmins & PNG_LOMASK;
2129 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2131 for (j = 0; j < num_p_filters; j++)
2132 {
2133 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
2134 {
2135 lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2136 PNG_WEIGHT_SHIFT;
2137 lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2138 PNG_WEIGHT_SHIFT;
2139 }
2140 }
2142 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2143 PNG_COST_SHIFT;
2144 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2145 PNG_COST_SHIFT;
2147 if (lmhi > PNG_HIMASK)
2148 lmins = PNG_MAXSUM;
2149 else
2150 lmins = (lmhi << PNG_HISHIFT) + lmlo;
2151 }
2152 #endif
2154 for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
2155 i++, rp++, dp++)
2156 {
2157 v = *dp = *rp;
2159 sum += (v < 128) ? v : 256 - v;
2160 }
2161 for (lp = row_buf + 1; i < row_info->rowbytes;
2162 i++, rp++, lp++, dp++)
2163 {
2164 v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
2166 sum += (v < 128) ? v : 256 - v;
2168 if (sum > lmins) /* We are already worse, don't continue. */
2169 break;
2170 }
2172 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2173 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2174 {
2175 int j;
2176 png_uint_32 sumhi, sumlo;
2177 sumlo = sum & PNG_LOMASK;
2178 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2180 for (j = 0; j < num_p_filters; j++)
2181 {
2182 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
2183 {
2184 sumlo = (sumlo * png_ptr->inv_filter_weights[j]) >>
2185 PNG_WEIGHT_SHIFT;
2186 sumhi = (sumhi * png_ptr->inv_filter_weights[j]) >>
2187 PNG_WEIGHT_SHIFT;
2188 }
2189 }
2191 sumlo = (sumlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2192 PNG_COST_SHIFT;
2193 sumhi = (sumhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2194 PNG_COST_SHIFT;
2196 if (sumhi > PNG_HIMASK)
2197 sum = PNG_MAXSUM;
2198 else
2199 sum = (sumhi << PNG_HISHIFT) + sumlo;
2200 }
2201 #endif
2203 if (sum < mins)
2204 {
2205 mins = sum;
2206 best_row = png_ptr->sub_row;
2207 }
2208 }
2210 /* up filter */
2211 if (filter_to_do == PNG_FILTER_UP)
2212 {
2213 png_bytep rp, dp, pp;
2214 png_uint_32 i;
2216 for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
2217 pp = prev_row + 1; i < row_bytes;
2218 i++, rp++, pp++, dp++)
2219 {
2220 *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
2221 }
2222 best_row = png_ptr->up_row;
2223 }
2225 else if (filter_to_do & PNG_FILTER_UP)
2226 {
2227 png_bytep rp, dp, pp;
2228 png_uint_32 sum = 0, lmins = mins;
2229 png_uint_32 i;
2230 int v;
2233 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2234 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2235 {
2236 int j;
2237 png_uint_32 lmhi, lmlo;
2238 lmlo = lmins & PNG_LOMASK;
2239 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2241 for (j = 0; j < num_p_filters; j++)
2242 {
2243 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
2244 {
2245 lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2246 PNG_WEIGHT_SHIFT;
2247 lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2248 PNG_WEIGHT_SHIFT;
2249 }
2250 }
2252 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
2253 PNG_COST_SHIFT;
2254 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
2255 PNG_COST_SHIFT;
2257 if (lmhi > PNG_HIMASK)
2258 lmins = PNG_MAXSUM;
2259 else
2260 lmins = (lmhi << PNG_HISHIFT) + lmlo;
2261 }
2262 #endif
2264 for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
2265 pp = prev_row + 1; i < row_bytes; i++)
2266 {
2267 v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2269 sum += (v < 128) ? v : 256 - v;
2271 if (sum > lmins) /* We are already worse, don't continue. */
2272 break;
2273 }
2275 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2276 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2277 {
2278 int j;
2279 png_uint_32 sumhi, sumlo;
2280 sumlo = sum & PNG_LOMASK;
2281 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2283 for (j = 0; j < num_p_filters; j++)
2284 {
2285 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
2286 {
2287 sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2288 PNG_WEIGHT_SHIFT;
2289 sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2290 PNG_WEIGHT_SHIFT;
2291 }
2292 }
2294 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
2295 PNG_COST_SHIFT;
2296 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
2297 PNG_COST_SHIFT;
2299 if (sumhi > PNG_HIMASK)
2300 sum = PNG_MAXSUM;
2301 else
2302 sum = (sumhi << PNG_HISHIFT) + sumlo;
2303 }
2304 #endif
2306 if (sum < mins)
2307 {
2308 mins = sum;
2309 best_row = png_ptr->up_row;
2310 }
2311 }
2313 /* avg filter */
2314 if (filter_to_do == PNG_FILTER_AVG)
2315 {
2316 png_bytep rp, dp, pp, lp;
2317 png_uint_32 i;
2318 for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
2319 pp = prev_row + 1; i < bpp; i++)
2320 {
2321 *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
2322 }
2323 for (lp = row_buf + 1; i < row_bytes; i++)
2324 {
2325 *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
2326 & 0xff);
2327 }
2328 best_row = png_ptr->avg_row;
2329 }
2331 else if (filter_to_do & PNG_FILTER_AVG)
2332 {
2333 png_bytep rp, dp, pp, lp;
2334 png_uint_32 sum = 0, lmins = mins;
2335 png_uint_32 i;
2336 int v;
2338 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2339 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2340 {
2341 int j;
2342 png_uint_32 lmhi, lmlo;
2343 lmlo = lmins & PNG_LOMASK;
2344 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2346 for (j = 0; j < num_p_filters; j++)
2347 {
2348 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_AVG)
2349 {
2350 lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2351 PNG_WEIGHT_SHIFT;
2352 lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2353 PNG_WEIGHT_SHIFT;
2354 }
2355 }
2357 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
2358 PNG_COST_SHIFT;
2359 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
2360 PNG_COST_SHIFT;
2362 if (lmhi > PNG_HIMASK)
2363 lmins = PNG_MAXSUM;
2364 else
2365 lmins = (lmhi << PNG_HISHIFT) + lmlo;
2366 }
2367 #endif
2369 for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
2370 pp = prev_row + 1; i < bpp; i++)
2371 {
2372 v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
2374 sum += (v < 128) ? v : 256 - v;
2375 }
2376 for (lp = row_buf + 1; i < row_bytes; i++)
2377 {
2378 v = *dp++ =
2379 (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) & 0xff);
2381 sum += (v < 128) ? v : 256 - v;
2383 if (sum > lmins) /* We are already worse, don't continue. */
2384 break;
2385 }
2387 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2388 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2389 {
2390 int j;
2391 png_uint_32 sumhi, sumlo;
2392 sumlo = sum & PNG_LOMASK;
2393 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2395 for (j = 0; j < num_p_filters; j++)
2396 {
2397 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
2398 {
2399 sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2400 PNG_WEIGHT_SHIFT;
2401 sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2402 PNG_WEIGHT_SHIFT;
2403 }
2404 }
2406 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
2407 PNG_COST_SHIFT;
2408 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
2409 PNG_COST_SHIFT;
2411 if (sumhi > PNG_HIMASK)
2412 sum = PNG_MAXSUM;
2413 else
2414 sum = (sumhi << PNG_HISHIFT) + sumlo;
2415 }
2416 #endif
2418 if (sum < mins)
2419 {
2420 mins = sum;
2421 best_row = png_ptr->avg_row;
2422 }
2423 }
2425 /* Paeth filter */
2426 if (filter_to_do == PNG_FILTER_PAETH)
2427 {
2428 png_bytep rp, dp, pp, cp, lp;
2429 png_uint_32 i;
2430 for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
2431 pp = prev_row + 1; i < bpp; i++)
2432 {
2433 *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2434 }
2436 for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
2437 {
2438 int a, b, c, pa, pb, pc, p;
2440 b = *pp++;
2441 c = *cp++;
2442 a = *lp++;
2444 p = b - c;
2445 pc = a - c;
2447 #ifdef PNG_USE_ABS
2448 pa = abs(p);
2449 pb = abs(pc);
2450 pc = abs(p + pc);
2451 #else
2452 pa = p < 0 ? -p : p;
2453 pb = pc < 0 ? -pc : pc;
2454 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
2455 #endif
2457 p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
2459 *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
2460 }
2461 best_row = png_ptr->paeth_row;
2462 }
2464 else if (filter_to_do & PNG_FILTER_PAETH)
2465 {
2466 png_bytep rp, dp, pp, cp, lp;
2467 png_uint_32 sum = 0, lmins = mins;
2468 png_uint_32 i;
2469 int v;
2471 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2472 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2473 {
2474 int j;
2475 png_uint_32 lmhi, lmlo;
2476 lmlo = lmins & PNG_LOMASK;
2477 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2479 for (j = 0; j < num_p_filters; j++)
2480 {
2481 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
2482 {
2483 lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2484 PNG_WEIGHT_SHIFT;
2485 lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2486 PNG_WEIGHT_SHIFT;
2487 }
2488 }
2490 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2491 PNG_COST_SHIFT;
2492 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2493 PNG_COST_SHIFT;
2495 if (lmhi > PNG_HIMASK)
2496 lmins = PNG_MAXSUM;
2497 else
2498 lmins = (lmhi << PNG_HISHIFT) + lmlo;
2499 }
2500 #endif
2502 for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
2503 pp = prev_row + 1; i < bpp; i++)
2504 {
2505 v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2507 sum += (v < 128) ? v : 256 - v;
2508 }
2510 for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
2511 {
2512 int a, b, c, pa, pb, pc, p;
2514 b = *pp++;
2515 c = *cp++;
2516 a = *lp++;
2518 #ifndef PNG_SLOW_PAETH
2519 p = b - c;
2520 pc = a - c;
2521 #ifdef PNG_USE_ABS
2522 pa = abs(p);
2523 pb = abs(pc);
2524 pc = abs(p + pc);
2525 #else
2526 pa = p < 0 ? -p : p;
2527 pb = pc < 0 ? -pc : pc;
2528 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
2529 #endif
2530 p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
2531 #else /* PNG_SLOW_PAETH */
2532 p = a + b - c;
2533 pa = abs(p - a);
2534 pb = abs(p - b);
2535 pc = abs(p - c);
2536 if (pa <= pb && pa <= pc)
2537 p = a;
2538 else if (pb <= pc)
2539 p = b;
2540 else
2541 p = c;
2542 #endif /* PNG_SLOW_PAETH */
2544 v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
2546 sum += (v < 128) ? v : 256 - v;
2548 if (sum > lmins) /* We are already worse, don't continue. */
2549 break;
2550 }
2552 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2553 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2554 {
2555 int j;
2556 png_uint_32 sumhi, sumlo;
2557 sumlo = sum & PNG_LOMASK;
2558 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2560 for (j = 0; j < num_p_filters; j++)
2561 {
2562 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
2563 {
2564 sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2565 PNG_WEIGHT_SHIFT;
2566 sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2567 PNG_WEIGHT_SHIFT;
2568 }
2569 }
2571 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2572 PNG_COST_SHIFT;
2573 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2574 PNG_COST_SHIFT;
2576 if (sumhi > PNG_HIMASK)
2577 sum = PNG_MAXSUM;
2578 else
2579 sum = (sumhi << PNG_HISHIFT) + sumlo;
2580 }
2581 #endif
2583 if (sum < mins)
2584 {
2585 best_row = png_ptr->paeth_row;
2586 }
2587 }
2589 /* Do the actual writing of the filtered row data from the chosen filter. */
2591 png_write_filtered_row(png_ptr, best_row);
2593 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2594 /* Save the type of filter we picked this time for future calculations */
2595 if (png_ptr->num_prev_filters > 0)
2596 {
2597 int j;
2598 for (j = 1; j < num_p_filters; j++)
2599 {
2600 png_ptr->prev_filters[j] = png_ptr->prev_filters[j - 1];
2601 }
2602 png_ptr->prev_filters[j] = best_row[0];
2603 }
2604 #endif
2605 }
2608 /* Do the actual writing of a previously filtered row. */
2609 void /* PRIVATE */
2610 png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row)
2611 {
2612 png_debug(1, "in png_write_filtered_row\n");
2613 png_debug1(2, "filter = %d\n", filtered_row[0]);
2614 /* set up the zlib input buffer */
2616 png_ptr->zstream.next_in = filtered_row;
2617 png_ptr->zstream.avail_in = (uInt)png_ptr->row_info.rowbytes + 1;
2618 /* repeat until we have compressed all the data */
2619 do
2620 {
2621 int ret; /* return of zlib */
2623 /* compress the data */
2624 ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
2625 /* check for compression errors */
2626 if (ret != Z_OK)
2627 {
2628 if (png_ptr->zstream.msg != NULL)
2629 png_error(png_ptr, png_ptr->zstream.msg);
2630 else
2631 png_error(png_ptr, "zlib error");
2632 }
2634 /* see if it is time to write another IDAT */
2635 if (!(png_ptr->zstream.avail_out))
2636 {
2637 /* write the IDAT and reset the zlib output buffer */
2638 png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
2639 png_ptr->zstream.next_out = png_ptr->zbuf;
2640 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
2641 }
2642 /* repeat until all data has been compressed */
2643 } while (png_ptr->zstream.avail_in);
2645 /* swap the current and previous rows */
2646 if (png_ptr->prev_row != NULL)
2647 {
2648 png_bytep tptr;
2650 tptr = png_ptr->prev_row;
2651 png_ptr->prev_row = png_ptr->row_buf;
2652 png_ptr->row_buf = tptr;
2653 }
2655 /* finish row - updates counters and flushes zlib if last row */
2656 png_write_finish_row(png_ptr);
2658 #if defined(PNG_WRITE_FLUSH_SUPPORTED)
2659 png_ptr->flush_rows++;
2661 if (png_ptr->flush_dist > 0 &&
2662 png_ptr->flush_rows >= png_ptr->flush_dist)
2663 {
2664 png_write_flush(png_ptr);
2665 }
2666 #endif
2667 }
2668 #endif /* PNG_WRITE_SUPPORTED */