2 /* pngwutil.c - utilities to write a PNG file
3 *
4 * libpng 1.0.9 - January 31, 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"
14 /* Place a 32-bit number into a buffer in PNG byte order. We work
15 * with unsigned numbers for convenience, although one supported
16 * ancillary chunk uses signed (two's complement) numbers.
17 */
18 void /* PRIVATE */
19 png_save_uint_32(png_bytep buf, png_uint_32 i)
20 {
21 buf[0] = (png_byte)((i >> 24) & 0xff);
22 buf[1] = (png_byte)((i >> 16) & 0xff);
23 buf[2] = (png_byte)((i >> 8) & 0xff);
24 buf[3] = (png_byte)(i & 0xff);
25 }
27 #if defined(PNG_WRITE_pCAL_SUPPORTED)
28 /* The png_save_int_32 function assumes integers are stored in two's
29 * complement format. If this isn't the case, then this routine needs to
30 * be modified to write data in two's complement format.
31 */
32 void /* PRIVATE */
33 png_save_int_32(png_bytep buf, png_int_32 i)
34 {
35 buf[0] = (png_byte)((i >> 24) & 0xff);
36 buf[1] = (png_byte)((i >> 16) & 0xff);
37 buf[2] = (png_byte)((i >> 8) & 0xff);
38 buf[3] = (png_byte)(i & 0xff);
39 }
40 #endif
42 /* Place a 16-bit number into a buffer in PNG byte order.
43 * The parameter is declared unsigned int, not png_uint_16,
44 * just to avoid potential problems on pre-ANSI C compilers.
45 */
46 void /* PRIVATE */
47 png_save_uint_16(png_bytep buf, unsigned int i)
48 {
49 buf[0] = (png_byte)((i >> 8) & 0xff);
50 buf[1] = (png_byte)(i & 0xff);
51 }
53 /* Write a PNG chunk all at once. The type is an array of ASCII characters
54 * representing the chunk name. The array must be at least 4 bytes in
55 * length, and does not need to be null terminated. To be safe, pass the
56 * pre-defined chunk names here, and if you need a new one, define it
57 * where the others are defined. The length is the length of the data.
58 * All the data must be present. If that is not possible, use the
59 * png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end()
60 * functions instead.
61 */
62 void PNGAPI
63 png_write_chunk(png_structp png_ptr, png_bytep chunk_name,
64 png_bytep data, png_size_t length)
65 {
66 png_write_chunk_start(png_ptr, chunk_name, (png_uint_32)length);
67 png_write_chunk_data(png_ptr, data, length);
68 png_write_chunk_end(png_ptr);
69 }
71 /* Write the start of a PNG chunk. The type is the chunk type.
72 * The total_length is the sum of the lengths of all the data you will be
73 * passing in png_write_chunk_data().
74 */
75 void PNGAPI
76 png_write_chunk_start(png_structp png_ptr, png_bytep chunk_name,
77 png_uint_32 length)
78 {
79 png_byte buf[4];
80 png_debug2(0, "Writing %s chunk (%lu bytes)\n", chunk_name, length);
82 /* write the length */
83 png_save_uint_32(buf, length);
84 png_write_data(png_ptr, buf, (png_size_t)4);
86 /* write the chunk name */
87 png_write_data(png_ptr, chunk_name, (png_size_t)4);
88 /* reset the crc and run it over the chunk name */
89 png_reset_crc(png_ptr);
90 png_calculate_crc(png_ptr, chunk_name, (png_size_t)4);
91 }
93 /* Write the data of a PNG chunk started with png_write_chunk_start().
94 * Note that multiple calls to this function are allowed, and that the
95 * sum of the lengths from these calls *must* add up to the total_length
96 * given to png_write_chunk_start().
97 */
98 void PNGAPI
99 png_write_chunk_data(png_structp png_ptr, png_bytep data, png_size_t length)
100 {
101 /* write the data, and run the CRC over it */
102 if (data != NULL && length > 0)
103 {
104 png_calculate_crc(png_ptr, data, length);
105 png_write_data(png_ptr, data, length);
106 }
107 }
109 /* Finish a chunk started with png_write_chunk_start(). */
110 void PNGAPI
111 png_write_chunk_end(png_structp png_ptr)
112 {
113 png_byte buf[4];
115 /* write the crc */
116 png_save_uint_32(buf, png_ptr->crc);
118 png_write_data(png_ptr, buf, (png_size_t)4);
119 }
121 /* Simple function to write the signature. If we have already written
122 * the magic bytes of the signature, or more likely, the PNG stream is
123 * being embedded into another stream and doesn't need its own signature,
124 * we should call png_set_sig_bytes() to tell libpng how many of the
125 * bytes have already been written.
126 */
127 void /* PRIVATE */
128 png_write_sig(png_structp png_ptr)
129 {
130 png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
131 /* write the rest of the 8 byte signature */
132 png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes],
133 (png_size_t)8 - png_ptr->sig_bytes);
134 if(png_ptr->sig_bytes < 3)
135 png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
136 }
138 #if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_iCCP_SUPPORTED)
139 /*
140 * This pair of functions encapsulates the operation of (a) compressing a
141 * text string, and (b) issuing it later as a series of chunk data writes.
142 * The compression_state structure is shared context for these functions
143 * set up by the caller in order to make the whole mess thread-safe.
144 */
146 typedef struct
147 {
148 char *input; /* the uncompressed input data */
149 int input_len; /* its length */
150 int num_output_ptr; /* number of output pointers used */
151 int max_output_ptr; /* size of output_ptr */
152 png_charpp output_ptr; /* array of pointers to output */
153 } compression_state;
155 /* compress given text into storage in the png_ptr structure */
156 static int /* PRIVATE */
157 png_text_compress(png_structp png_ptr,
158 png_charp text, png_size_t text_len, int compression,
159 compression_state *comp)
160 {
161 int ret;
163 comp->num_output_ptr = comp->max_output_ptr = 0;
164 comp->output_ptr = NULL;
165 comp->input = NULL;
167 /* we may just want to pass the text right through */
168 if (compression == PNG_TEXT_COMPRESSION_NONE)
169 {
170 comp->input = text;
171 comp->input_len = text_len;
172 return((int)text_len);
173 }
175 if (compression >= PNG_TEXT_COMPRESSION_LAST)
176 {
177 #if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
178 char msg[50];
179 sprintf(msg, "Unknown compression type %d", compression);
180 png_warning(png_ptr, msg);
181 #else
182 png_warning(png_ptr, "Unknown compression type");
183 #endif
184 }
186 /* We can't write the chunk until we find out how much data we have,
187 * which means we need to run the compressor first and save the
188 * output. This shouldn't be a problem, as the vast majority of
189 * comments should be reasonable, but we will set up an array of
190 * malloc'd pointers to be sure.
191 *
192 * If we knew the application was well behaved, we could simplify this
193 * greatly by assuming we can always malloc an output buffer large
194 * enough to hold the compressed text ((1001 * text_len / 1000) + 12)
195 * and malloc this directly. The only time this would be a bad idea is
196 * if we can't malloc more than 64K and we have 64K of random input
197 * data, or if the input string is incredibly large (although this
198 * wouldn't cause a failure, just a slowdown due to swapping).
199 */
201 /* set up the compression buffers */
202 png_ptr->zstream.avail_in = (uInt)text_len;
203 png_ptr->zstream.next_in = (Bytef *)text;
204 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
205 png_ptr->zstream.next_out = (Bytef *)png_ptr->zbuf;
207 /* this is the same compression loop as in png_write_row() */
208 do
209 {
210 /* compress the data */
211 ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
212 if (ret != Z_OK)
213 {
214 /* error */
215 if (png_ptr->zstream.msg != NULL)
216 png_error(png_ptr, png_ptr->zstream.msg);
217 else
218 png_error(png_ptr, "zlib error");
219 }
220 /* check to see if we need more room */
221 if (!png_ptr->zstream.avail_out && png_ptr->zstream.avail_in)
222 {
223 /* make sure the output array has room */
224 if (comp->num_output_ptr >= comp->max_output_ptr)
225 {
226 int old_max;
228 old_max = comp->max_output_ptr;
229 comp->max_output_ptr = comp->num_output_ptr + 4;
230 if (comp->output_ptr != NULL)
231 {
232 png_charpp old_ptr;
234 old_ptr = comp->output_ptr;
235 comp->output_ptr = (png_charpp)png_malloc(png_ptr,
236 (png_uint_32)(comp->max_output_ptr * sizeof (png_charpp)));
237 png_memcpy(comp->output_ptr, old_ptr,
238 old_max * sizeof (png_charp));
239 png_free(png_ptr, old_ptr);
240 }
241 else
242 comp->output_ptr = (png_charpp)png_malloc(png_ptr,
243 (png_uint_32)(comp->max_output_ptr * sizeof (png_charp)));
244 }
246 /* save the data */
247 comp->output_ptr[comp->num_output_ptr] = (png_charp)png_malloc(png_ptr,
248 (png_uint_32)png_ptr->zbuf_size);
249 png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
250 png_ptr->zbuf_size);
251 comp->num_output_ptr++;
253 /* and reset the buffer */
254 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
255 png_ptr->zstream.next_out = png_ptr->zbuf;
256 }
257 /* continue until we don't have any more to compress */
258 } while (png_ptr->zstream.avail_in);
260 /* finish the compression */
261 do
262 {
263 /* tell zlib we are finished */
264 ret = deflate(&png_ptr->zstream, Z_FINISH);
266 if (ret == Z_OK)
267 {
268 /* check to see if we need more room */
269 if (!(png_ptr->zstream.avail_out))
270 {
271 /* check to make sure our output array has room */
272 if (comp->num_output_ptr >= comp->max_output_ptr)
273 {
274 int old_max;
276 old_max = comp->max_output_ptr;
277 comp->max_output_ptr = comp->num_output_ptr + 4;
278 if (comp->output_ptr != NULL)
279 {
280 png_charpp old_ptr;
282 old_ptr = comp->output_ptr;
283 /* This could be optimized to realloc() */
284 comp->output_ptr = (png_charpp)png_malloc(png_ptr,
285 (png_uint_32)(comp->max_output_ptr * sizeof (png_charpp)));
286 png_memcpy(comp->output_ptr, old_ptr,
287 old_max * sizeof (png_charp));
288 png_free(png_ptr, old_ptr);
289 }
290 else
291 comp->output_ptr = (png_charpp)png_malloc(png_ptr,
292 (png_uint_32)(comp->max_output_ptr * sizeof (png_charp)));
293 }
295 /* save off the data */
296 comp->output_ptr[comp->num_output_ptr] =
297 (png_charp)png_malloc(png_ptr, (png_uint_32)png_ptr->zbuf_size);
298 png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
299 png_ptr->zbuf_size);
300 comp->num_output_ptr++;
302 /* and reset the buffer pointers */
303 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
304 png_ptr->zstream.next_out = png_ptr->zbuf;
305 }
306 }
307 else if (ret != Z_STREAM_END)
308 {
309 /* we got an error */
310 if (png_ptr->zstream.msg != NULL)
311 png_error(png_ptr, png_ptr->zstream.msg);
312 else
313 png_error(png_ptr, "zlib error");
314 }
315 } while (ret != Z_STREAM_END);
317 /* text length is number of buffers plus last buffer */
318 text_len = png_ptr->zbuf_size * comp->num_output_ptr;
319 if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
320 text_len += png_ptr->zbuf_size - (png_size_t)png_ptr->zstream.avail_out;
322 return((int)text_len);
323 }
325 /* ship the compressed text out via chunk writes */
326 static void /* PRIVATE */
327 png_write_compressed_data_out(png_structp png_ptr, compression_state *comp)
328 {
329 int i;
331 /* handle the no-compression case */
332 if (comp->input)
333 {
334 png_write_chunk_data(png_ptr, (png_bytep)comp->input, comp->input_len);
335 return;
336 }
338 /* write saved output buffers, if any */
339 for (i = 0; i < comp->num_output_ptr; i++)
340 {
341 png_write_chunk_data(png_ptr,(png_bytep)comp->output_ptr[i],
342 png_ptr->zbuf_size);
343 png_free(png_ptr, comp->output_ptr[i]);
344 comp->output_ptr[i]=NULL;
345 }
346 if (comp->max_output_ptr != 0)
347 png_free(png_ptr, comp->output_ptr);
348 comp->output_ptr=NULL;
349 /* write anything left in zbuf */
350 if (png_ptr->zstream.avail_out < (png_uint_32)png_ptr->zbuf_size)
351 png_write_chunk_data(png_ptr, png_ptr->zbuf,
352 png_ptr->zbuf_size - png_ptr->zstream.avail_out);
354 /* reset zlib for another zTXt/iTXt or the image data */
355 deflateReset(&png_ptr->zstream);
357 }
358 #endif
360 /* Write the IHDR chunk, and update the png_struct with the necessary
361 * information. Note that the rest of this code depends upon this
362 * information being correct.
363 */
364 void /* PRIVATE */
365 png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
366 int bit_depth, int color_type, int compression_type, int filter_type,
367 int interlace_type)
368 {
369 #ifdef PNG_USE_LOCAL_ARRAYS
370 PNG_IHDR;
371 #endif
372 png_byte buf[13]; /* buffer to store the IHDR info */
374 png_debug(1, "in png_write_IHDR\n");
375 /* Check that we have valid input data from the application info */
376 switch (color_type)
377 {
378 case PNG_COLOR_TYPE_GRAY:
379 switch (bit_depth)
380 {
381 case 1:
382 case 2:
383 case 4:
384 case 8:
385 case 16: png_ptr->channels = 1; break;
386 default: png_error(png_ptr,"Invalid bit depth for grayscale image");
387 }
388 break;
389 case PNG_COLOR_TYPE_RGB:
390 if (bit_depth != 8 && bit_depth != 16)
391 png_error(png_ptr, "Invalid bit depth for RGB image");
392 png_ptr->channels = 3;
393 break;
394 case PNG_COLOR_TYPE_PALETTE:
395 switch (bit_depth)
396 {
397 case 1:
398 case 2:
399 case 4:
400 case 8: png_ptr->channels = 1; break;
401 default: png_error(png_ptr, "Invalid bit depth for paletted image");
402 }
403 break;
404 case PNG_COLOR_TYPE_GRAY_ALPHA:
405 if (bit_depth != 8 && bit_depth != 16)
406 png_error(png_ptr, "Invalid bit depth for grayscale+alpha image");
407 png_ptr->channels = 2;
408 break;
409 case PNG_COLOR_TYPE_RGB_ALPHA:
410 if (bit_depth != 8 && bit_depth != 16)
411 png_error(png_ptr, "Invalid bit depth for RGBA image");
412 png_ptr->channels = 4;
413 break;
414 default:
415 png_error(png_ptr, "Invalid image color type specified");
416 }
418 if (compression_type != PNG_COMPRESSION_TYPE_BASE)
419 {
420 png_warning(png_ptr, "Invalid compression type specified");
421 compression_type = PNG_COMPRESSION_TYPE_BASE;
422 }
424 /* Write filter_method 64 (intrapixel differencing) only if
425 * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
426 * 2. Libpng did not write a PNG signature (this filter_method is only
427 * used in PNG datastreams that are embedded in MNG datastreams) and
428 * 3. The application called png_permit_mng_features with a mask that
429 * included PNG_FLAG_MNG_FILTER_64 and
430 * 4. The filter_method is 64 and
431 * 5. The color_type is RGB or RGBA
432 */
433 if (
434 #if defined(PNG_MNG_FEATURES_SUPPORTED)
435 !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
436 ((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE) == 0) &&
437 (color_type == PNG_COLOR_TYPE_RGB ||
438 color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&
439 (filter_type == PNG_INTRAPIXEL_DIFFERENCING)) &&
440 #endif
441 filter_type != PNG_FILTER_TYPE_BASE)
442 {
443 png_warning(png_ptr, "Invalid filter type specified");
444 filter_type = PNG_FILTER_TYPE_BASE;
445 }
447 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
448 if (interlace_type != PNG_INTERLACE_NONE &&
449 interlace_type != PNG_INTERLACE_ADAM7)
450 {
451 png_warning(png_ptr, "Invalid interlace type specified");
452 interlace_type = PNG_INTERLACE_ADAM7;
453 }
454 #else
455 interlace_type=PNG_INTERLACE_NONE;
456 #endif
458 /* save off the relevent information */
459 png_ptr->bit_depth = (png_byte)bit_depth;
460 png_ptr->color_type = (png_byte)color_type;
461 png_ptr->interlaced = (png_byte)interlace_type;
462 png_ptr->filter_type = (png_byte)filter_type;
463 png_ptr->width = width;
464 png_ptr->height = height;
466 png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels);
467 png_ptr->rowbytes = ((width * (png_size_t)png_ptr->pixel_depth + 7) >> 3);
468 /* set the usr info, so any transformations can modify it */
469 png_ptr->usr_width = png_ptr->width;
470 png_ptr->usr_bit_depth = png_ptr->bit_depth;
471 png_ptr->usr_channels = png_ptr->channels;
473 /* pack the header information into the buffer */
474 png_save_uint_32(buf, width);
475 png_save_uint_32(buf + 4, height);
476 buf[8] = (png_byte)bit_depth;
477 buf[9] = (png_byte)color_type;
478 buf[10] = (png_byte)compression_type;
479 buf[11] = (png_byte)filter_type;
480 buf[12] = (png_byte)interlace_type;
482 /* write the chunk */
483 png_write_chunk(png_ptr, (png_bytep)png_IHDR, buf, (png_size_t)13);
485 /* initialize zlib with PNG info */
486 png_ptr->zstream.zalloc = png_zalloc;
487 png_ptr->zstream.zfree = png_zfree;
488 png_ptr->zstream.opaque = (voidpf)png_ptr;
489 if (!(png_ptr->do_filter))
490 {
491 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
492 png_ptr->bit_depth < 8)
493 png_ptr->do_filter = PNG_FILTER_NONE;
494 else
495 png_ptr->do_filter = PNG_ALL_FILTERS;
496 }
497 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY))
498 {
499 if (png_ptr->do_filter != PNG_FILTER_NONE)
500 png_ptr->zlib_strategy = Z_FILTERED;
501 else
502 png_ptr->zlib_strategy = Z_DEFAULT_STRATEGY;
503 }
504 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_LEVEL))
505 png_ptr->zlib_level = Z_DEFAULT_COMPRESSION;
506 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL))
507 png_ptr->zlib_mem_level = 8;
508 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS))
509 png_ptr->zlib_window_bits = 15;
510 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_METHOD))
511 png_ptr->zlib_method = 8;
512 deflateInit2(&png_ptr->zstream, png_ptr->zlib_level,
513 png_ptr->zlib_method, png_ptr->zlib_window_bits,
514 png_ptr->zlib_mem_level, png_ptr->zlib_strategy);
515 png_ptr->zstream.next_out = png_ptr->zbuf;
516 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
518 png_ptr->mode = PNG_HAVE_IHDR;
519 }
521 /* write the palette. We are careful not to trust png_color to be in the
522 * correct order for PNG, so people can redefine it to any convenient
523 * structure.
524 */
525 void /* PRIVATE */
526 png_write_PLTE(png_structp png_ptr, png_colorp palette, png_uint_32 num_pal)
527 {
528 #ifdef PNG_USE_LOCAL_ARRAYS
529 PNG_PLTE;
530 #endif
531 png_uint_32 i;
532 png_colorp pal_ptr;
533 png_byte buf[3];
535 png_debug(1, "in png_write_PLTE\n");
536 if ((
537 #if defined(PNG_MNG_FEATURES_SUPPORTED)
538 !(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) &&
539 #endif
540 num_pal == 0) || num_pal > 256)
541 {
542 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
543 {
544 png_error(png_ptr, "Invalid number of colors in palette");
545 }
546 else
547 {
548 png_warning(png_ptr, "Invalid number of colors in palette");
549 return;
550 }
551 }
553 png_ptr->num_palette = (png_uint_16)num_pal;
554 png_debug1(3, "num_palette = %d\n", png_ptr->num_palette);
556 png_write_chunk_start(png_ptr, (png_bytep)png_PLTE, num_pal * 3);
557 #ifndef PNG_NO_POINTER_INDEXING
558 for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++)
559 {
560 buf[0] = pal_ptr->red;
561 buf[1] = pal_ptr->green;
562 buf[2] = pal_ptr->blue;
563 png_write_chunk_data(png_ptr, buf, (png_size_t)3);
564 }
565 #else
566 /* This is a little slower but some buggy compilers need to do this instead */
567 pal_ptr=palette;
568 for (i = 0; i < num_pal; i++)
569 {
570 buf[0] = pal_ptr[i].red;
571 buf[1] = pal_ptr[i].green;
572 buf[2] = pal_ptr[i].blue;
573 png_write_chunk_data(png_ptr, buf, (png_size_t)3);
574 }
575 #endif
576 png_write_chunk_end(png_ptr);
577 png_ptr->mode |= PNG_HAVE_PLTE;
578 }
580 /* write an IDAT chunk */
581 void /* PRIVATE */
582 png_write_IDAT(png_structp png_ptr, png_bytep data, png_size_t length)
583 {
584 #ifdef PNG_USE_LOCAL_ARRAYS
585 PNG_IDAT;
586 #endif
587 png_debug(1, "in png_write_IDAT\n");
588 png_write_chunk(png_ptr, (png_bytep)png_IDAT, data, length);
589 png_ptr->mode |= PNG_HAVE_IDAT;
590 }
592 /* write an IEND chunk */
593 void /* PRIVATE */
594 png_write_IEND(png_structp png_ptr)
595 {
596 #ifdef PNG_USE_LOCAL_ARRAYS
597 PNG_IEND;
598 #endif
599 png_debug(1, "in png_write_IEND\n");
600 png_write_chunk(png_ptr, (png_bytep)png_IEND, NULL, (png_size_t)0);
601 png_ptr->mode |= PNG_HAVE_IEND;
602 }
604 #if defined(PNG_WRITE_gAMA_SUPPORTED)
605 /* write a gAMA chunk */
606 #ifdef PNG_FLOATING_POINT_SUPPORTED
607 void /* PRIVATE */
608 png_write_gAMA(png_structp png_ptr, double file_gamma)
609 {
610 #ifdef PNG_USE_LOCAL_ARRAYS
611 PNG_gAMA;
612 #endif
613 png_uint_32 igamma;
614 png_byte buf[4];
616 png_debug(1, "in png_write_gAMA\n");
617 /* file_gamma is saved in 1/100,000ths */
618 igamma = (png_uint_32)(file_gamma * 100000.0 + 0.5);
619 png_save_uint_32(buf, igamma);
620 png_write_chunk(png_ptr, (png_bytep)png_gAMA, buf, (png_size_t)4);
621 }
622 #endif
623 #ifdef PNG_FIXED_POINT_SUPPORTED
624 void /* PRIVATE */
625 png_write_gAMA_fixed(png_structp png_ptr, png_fixed_point file_gamma)
626 {
627 #ifdef PNG_USE_LOCAL_ARRAYS
628 PNG_gAMA;
629 #endif
630 png_byte buf[4];
632 png_debug(1, "in png_write_gAMA\n");
633 /* file_gamma is saved in 1/100,000ths */
634 png_save_uint_32(buf, file_gamma);
635 png_write_chunk(png_ptr, (png_bytep)png_gAMA, buf, (png_size_t)4);
636 }
637 #endif
638 #endif
640 #if defined(PNG_WRITE_sRGB_SUPPORTED)
641 /* write a sRGB chunk */
642 void /* PRIVATE */
643 png_write_sRGB(png_structp png_ptr, int srgb_intent)
644 {
645 #ifdef PNG_USE_LOCAL_ARRAYS
646 PNG_sRGB;
647 #endif
648 png_byte buf[1];
650 png_debug(1, "in png_write_sRGB\n");
651 if(srgb_intent >= PNG_sRGB_INTENT_LAST)
652 png_warning(png_ptr,
653 "Invalid sRGB rendering intent specified");
654 buf[0]=(png_byte)srgb_intent;
655 png_write_chunk(png_ptr, (png_bytep)png_sRGB, buf, (png_size_t)1);
656 }
657 #endif
659 #if defined(PNG_WRITE_iCCP_SUPPORTED)
660 /* write an iCCP chunk */
661 void /* PRIVATE */
662 png_write_iCCP(png_structp png_ptr, png_charp name, int compression_type,
663 png_charp profile, int profile_len)
664 {
665 #ifdef PNG_USE_LOCAL_ARRAYS
666 PNG_iCCP;
667 #endif
668 png_size_t name_len;
669 png_charp new_name;
670 compression_state comp;
672 png_debug(1, "in png_write_iCCP\n");
673 if (name == NULL || (name_len = png_check_keyword(png_ptr, name,
674 &new_name)) == 0)
675 {
676 png_warning(png_ptr, "Empty keyword in iCCP chunk");
677 return;
678 }
680 if (compression_type != PNG_COMPRESSION_TYPE_BASE)
681 png_warning(png_ptr, "Unknown compression type in iCCP chunk");
683 if (profile == NULL)
684 profile_len = 0;
686 if (profile_len)
687 profile_len = png_text_compress(png_ptr, profile, (png_size_t)profile_len,
688 PNG_COMPRESSION_TYPE_BASE, &comp);
690 /* make sure we include the NULL after the name and the compression type */
691 png_write_chunk_start(png_ptr, (png_bytep)png_iCCP,
692 (png_uint_32)name_len+profile_len+2);
693 new_name[name_len+1]=0x00;
694 png_write_chunk_data(png_ptr, (png_bytep)new_name, name_len + 2);
696 if (profile_len)
697 png_write_compressed_data_out(png_ptr, &comp);
699 png_write_chunk_end(png_ptr);
700 png_free(png_ptr, new_name);
701 }
702 #endif
704 #if defined(PNG_WRITE_sPLT_SUPPORTED)
705 /* write a sPLT chunk */
706 void /* PRIVATE */
707 png_write_sPLT(png_structp png_ptr, png_sPLT_tp spalette)
708 {
709 #ifdef PNG_USE_LOCAL_ARRAYS
710 PNG_sPLT;
711 #endif
712 png_size_t name_len;
713 png_charp new_name;
714 png_byte entrybuf[10];
715 int entry_size = (spalette->depth == 8 ? 6 : 10);
716 int palette_size = entry_size * spalette->nentries;
717 png_sPLT_entryp ep;
718 #ifdef PNG_NO_POINTER_INDEXING
719 int i;
720 #endif
722 png_debug(1, "in png_write_sPLT\n");
723 if (spalette->name == NULL || (name_len = png_check_keyword(png_ptr,
724 spalette->name, &new_name))==0)
725 {
726 png_warning(png_ptr, "Empty keyword in sPLT chunk");
727 return;
728 }
730 /* make sure we include the NULL after the name */
731 png_write_chunk_start(png_ptr, (png_bytep) png_sPLT,
732 (png_uint_32)(name_len + 2 + palette_size));
733 png_write_chunk_data(png_ptr, (png_bytep)new_name, name_len + 1);
734 png_write_chunk_data(png_ptr, (png_bytep)&spalette->depth, 1);
736 /* loop through each palette entry, writing appropriately */
737 #ifndef PNG_NO_POINTER_INDEXING
738 for (ep = spalette->entries; ep<spalette->entries+spalette->nentries; ep++)
739 {
740 if (spalette->depth == 8)
741 {
742 entrybuf[0] = (png_byte)ep->red;
743 entrybuf[1] = (png_byte)ep->green;
744 entrybuf[2] = (png_byte)ep->blue;
745 entrybuf[3] = (png_byte)ep->alpha;
746 png_save_uint_16(entrybuf + 4, ep->frequency);
747 }
748 else
749 {
750 png_save_uint_16(entrybuf + 0, ep->red);
751 png_save_uint_16(entrybuf + 2, ep->green);
752 png_save_uint_16(entrybuf + 4, ep->blue);
753 png_save_uint_16(entrybuf + 6, ep->alpha);
754 png_save_uint_16(entrybuf + 8, ep->frequency);
755 }
756 png_write_chunk_data(png_ptr, entrybuf, entry_size);
757 }
758 #else
759 ep=spalette->entries;
760 for (i=0; i>spalette->nentries; i++)
761 {
762 if (spalette->depth == 8)
763 {
764 entrybuf[0] = (png_byte)ep[i].red;
765 entrybuf[1] = (png_byte)ep[i].green;
766 entrybuf[2] = (png_byte)ep[i].blue;
767 entrybuf[3] = (png_byte)ep[i].alpha;
768 png_save_uint_16(entrybuf + 4, ep[i].frequency);
769 }
770 else
771 {
772 png_save_uint_16(entrybuf + 0, ep[i].red);
773 png_save_uint_16(entrybuf + 2, ep[i].green);
774 png_save_uint_16(entrybuf + 4, ep[i].blue);
775 png_save_uint_16(entrybuf + 6, ep[i].alpha);
776 png_save_uint_16(entrybuf + 8, ep[i].frequency);
777 }
778 png_write_chunk_data(png_ptr, entrybuf, entry_size);
779 }
780 #endif
782 png_write_chunk_end(png_ptr);
783 png_free(png_ptr, new_name);
784 }
785 #endif
787 #if defined(PNG_WRITE_sBIT_SUPPORTED)
788 /* write the sBIT chunk */
789 void /* PRIVATE */
790 png_write_sBIT(png_structp png_ptr, png_color_8p sbit, int color_type)
791 {
792 #ifdef PNG_USE_LOCAL_ARRAYS
793 PNG_sBIT;
794 #endif
795 png_byte buf[4];
796 png_size_t size;
798 png_debug(1, "in png_write_sBIT\n");
799 /* make sure we don't depend upon the order of PNG_COLOR_8 */
800 if (color_type & PNG_COLOR_MASK_COLOR)
801 {
802 png_byte maxbits;
804 maxbits = (png_byte)(color_type==PNG_COLOR_TYPE_PALETTE ? 8 :
805 png_ptr->usr_bit_depth);
806 if (sbit->red == 0 || sbit->red > maxbits ||
807 sbit->green == 0 || sbit->green > maxbits ||
808 sbit->blue == 0 || sbit->blue > maxbits)
809 {
810 png_warning(png_ptr, "Invalid sBIT depth specified");
811 return;
812 }
813 buf[0] = sbit->red;
814 buf[1] = sbit->green;
815 buf[2] = sbit->blue;
816 size = 3;
817 }
818 else
819 {
820 if (sbit->gray == 0 || sbit->gray > png_ptr->usr_bit_depth)
821 {
822 png_warning(png_ptr, "Invalid sBIT depth specified");
823 return;
824 }
825 buf[0] = sbit->gray;
826 size = 1;
827 }
829 if (color_type & PNG_COLOR_MASK_ALPHA)
830 {
831 if (sbit->alpha == 0 || sbit->alpha > png_ptr->usr_bit_depth)
832 {
833 png_warning(png_ptr, "Invalid sBIT depth specified");
834 return;
835 }
836 buf[size++] = sbit->alpha;
837 }
839 png_write_chunk(png_ptr, (png_bytep)png_sBIT, buf, size);
840 }
841 #endif
843 #if defined(PNG_WRITE_cHRM_SUPPORTED)
844 /* write the cHRM chunk */
845 #ifdef PNG_FLOATING_POINT_SUPPORTED
846 void /* PRIVATE */
847 png_write_cHRM(png_structp png_ptr, double white_x, double white_y,
848 double red_x, double red_y, double green_x, double green_y,
849 double blue_x, double blue_y)
850 {
851 #ifdef PNG_USE_LOCAL_ARRAYS
852 PNG_cHRM;
853 #endif
854 png_byte buf[32];
855 png_uint_32 itemp;
857 png_debug(1, "in png_write_cHRM\n");
858 /* each value is saved in 1/100,000ths */
859 if (white_x < 0 || white_x > 0.8 || white_y < 0 || white_y > 0.8 ||
860 white_x + white_y > 1.0)
861 {
862 png_warning(png_ptr, "Invalid cHRM white point specified");
863 #if !defined(PNG_NO_CONSOLE_IO)
864 fprintf(stderr,"white_x=%f, white_y=%f\n",white_x, white_y);
865 #endif
866 return;
867 }
868 itemp = (png_uint_32)(white_x * 100000.0 + 0.5);
869 png_save_uint_32(buf, itemp);
870 itemp = (png_uint_32)(white_y * 100000.0 + 0.5);
871 png_save_uint_32(buf + 4, itemp);
873 if (red_x < 0 || red_x > 0.8 || red_y < 0 || red_y > 0.8 ||
874 red_x + red_y > 1.0)
875 {
876 png_warning(png_ptr, "Invalid cHRM red point specified");
877 return;
878 }
879 itemp = (png_uint_32)(red_x * 100000.0 + 0.5);
880 png_save_uint_32(buf + 8, itemp);
881 itemp = (png_uint_32)(red_y * 100000.0 + 0.5);
882 png_save_uint_32(buf + 12, itemp);
884 if (green_x < 0 || green_x > 0.8 || green_y < 0 || green_y > 0.8 ||
885 green_x + green_y > 1.0)
886 {
887 png_warning(png_ptr, "Invalid cHRM green point specified");
888 return;
889 }
890 itemp = (png_uint_32)(green_x * 100000.0 + 0.5);
891 png_save_uint_32(buf + 16, itemp);
892 itemp = (png_uint_32)(green_y * 100000.0 + 0.5);
893 png_save_uint_32(buf + 20, itemp);
895 if (blue_x < 0 || blue_x > 0.8 || blue_y < 0 || blue_y > 0.8 ||
896 blue_x + blue_y > 1.0)
897 {
898 png_warning(png_ptr, "Invalid cHRM blue point specified");
899 return;
900 }
901 itemp = (png_uint_32)(blue_x * 100000.0 + 0.5);
902 png_save_uint_32(buf + 24, itemp);
903 itemp = (png_uint_32)(blue_y * 100000.0 + 0.5);
904 png_save_uint_32(buf + 28, itemp);
906 png_write_chunk(png_ptr, (png_bytep)png_cHRM, buf, (png_size_t)32);
907 }
908 #endif
909 #ifdef PNG_FIXED_POINT_SUPPORTED
910 void /* PRIVATE */
911 png_write_cHRM_fixed(png_structp png_ptr, png_fixed_point white_x,
912 png_fixed_point white_y, png_fixed_point red_x, png_fixed_point red_y,
913 png_fixed_point green_x, png_fixed_point green_y, png_fixed_point blue_x,
914 png_fixed_point blue_y)
915 {
916 #ifdef PNG_USE_LOCAL_ARRAYS
917 PNG_cHRM;
918 #endif
919 png_byte buf[32];
921 png_debug(1, "in png_write_cHRM\n");
922 /* each value is saved in 1/100,000ths */
923 if (white_x > 80000L || white_y > 80000L || white_x + white_y > 100000L)
924 {
925 png_warning(png_ptr, "Invalid fixed cHRM white point specified");
926 #if !defined(PNG_NO_CONSOLE_IO)
927 fprintf(stderr,"white_x=%ld, white_y=%ld\n",white_x, white_y);
928 #endif
929 return;
930 }
931 png_save_uint_32(buf, white_x);
932 png_save_uint_32(buf + 4, white_y);
934 if (red_x > 80000L || red_y > 80000L || red_x + red_y > 100000L)
935 {
936 png_warning(png_ptr, "Invalid cHRM fixed red point specified");
937 return;
938 }
939 png_save_uint_32(buf + 8, red_x);
940 png_save_uint_32(buf + 12, red_y);
942 if (green_x > 80000L || green_y > 80000L || green_x + green_y > 100000L)
943 {
944 png_warning(png_ptr, "Invalid fixed cHRM green point specified");
945 return;
946 }
947 png_save_uint_32(buf + 16, green_x);
948 png_save_uint_32(buf + 20, green_y);
950 if (blue_x > 80000L || blue_y > 80000L || blue_x + blue_y > 100000L)
951 {
952 png_warning(png_ptr, "Invalid fixed cHRM blue point specified");
953 return;
954 }
955 png_save_uint_32(buf + 24, blue_x);
956 png_save_uint_32(buf + 28, blue_y);
958 png_write_chunk(png_ptr, (png_bytep)png_cHRM, buf, (png_size_t)32);
959 }
960 #endif
961 #endif
963 #if defined(PNG_WRITE_tRNS_SUPPORTED)
964 /* write the tRNS chunk */
965 void /* PRIVATE */
966 png_write_tRNS(png_structp png_ptr, png_bytep trans, png_color_16p tran,
967 int num_trans, int color_type)
968 {
969 #ifdef PNG_USE_LOCAL_ARRAYS
970 PNG_tRNS;
971 #endif
972 png_byte buf[6];
974 png_debug(1, "in png_write_tRNS\n");
975 if (color_type == PNG_COLOR_TYPE_PALETTE)
976 {
977 if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette)
978 {
979 png_warning(png_ptr,"Invalid number of transparent colors specified");
980 return;
981 }
982 /* write the chunk out as it is */
983 png_write_chunk(png_ptr, (png_bytep)png_tRNS, trans, (png_size_t)num_trans);
984 }
985 else if (color_type == PNG_COLOR_TYPE_GRAY)
986 {
987 /* one 16 bit value */
988 png_save_uint_16(buf, tran->gray);
989 png_write_chunk(png_ptr, (png_bytep)png_tRNS, buf, (png_size_t)2);
990 }
991 else if (color_type == PNG_COLOR_TYPE_RGB)
992 {
993 /* three 16 bit values */
994 png_save_uint_16(buf, tran->red);
995 png_save_uint_16(buf + 2, tran->green);
996 png_save_uint_16(buf + 4, tran->blue);
997 png_write_chunk(png_ptr, (png_bytep)png_tRNS, buf, (png_size_t)6);
998 }
999 else
1000 {
1001 png_warning(png_ptr, "Can't write tRNS with an alpha channel");
1002 }
1003 }
1004 #endif
1006 #if defined(PNG_WRITE_bKGD_SUPPORTED)
1007 /* write the background chunk */
1008 void /* PRIVATE */
1009 png_write_bKGD(png_structp png_ptr, png_color_16p back, int color_type)
1010 {
1011 #ifdef PNG_USE_LOCAL_ARRAYS
1012 PNG_bKGD;
1013 #endif
1014 png_byte buf[6];
1016 png_debug(1, "in png_write_bKGD\n");
1017 if (color_type == PNG_COLOR_TYPE_PALETTE)
1018 {
1019 if (
1020 #if defined(PNG_MNG_FEATURES_SUPPORTED)
1021 (png_ptr->num_palette ||
1022 (!(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE))) &&
1023 #endif
1024 back->index > png_ptr->num_palette)
1025 {
1026 png_warning(png_ptr, "Invalid background palette index");
1027 return;
1028 }
1029 buf[0] = back->index;
1030 png_write_chunk(png_ptr, (png_bytep)png_bKGD, buf, (png_size_t)1);
1031 }
1032 else if (color_type & PNG_COLOR_MASK_COLOR)
1033 {
1034 png_save_uint_16(buf, back->red);
1035 png_save_uint_16(buf + 2, back->green);
1036 png_save_uint_16(buf + 4, back->blue);
1037 png_write_chunk(png_ptr, (png_bytep)png_bKGD, buf, (png_size_t)6);
1038 }
1039 else
1040 {
1041 png_save_uint_16(buf, back->gray);
1042 png_write_chunk(png_ptr, (png_bytep)png_bKGD, buf, (png_size_t)2);
1043 }
1044 }
1045 #endif
1047 #if defined(PNG_WRITE_hIST_SUPPORTED)
1048 /* write the histogram */
1049 void /* PRIVATE */
1050 png_write_hIST(png_structp png_ptr, png_uint_16p hist, int num_hist)
1051 {
1052 #ifdef PNG_USE_LOCAL_ARRAYS
1053 PNG_hIST;
1054 #endif
1055 int i;
1056 png_byte buf[3];
1058 png_debug(1, "in png_write_hIST\n");
1059 if (num_hist > (int)png_ptr->num_palette)
1060 {
1061 png_debug2(3, "num_hist = %d, num_palette = %d\n", num_hist,
1062 png_ptr->num_palette);
1063 png_warning(png_ptr, "Invalid number of histogram entries specified");
1064 return;
1065 }
1067 png_write_chunk_start(png_ptr, (png_bytep)png_hIST, (png_uint_32)(num_hist * 2));
1068 for (i = 0; i < num_hist; i++)
1069 {
1070 png_save_uint_16(buf, hist[i]);
1071 png_write_chunk_data(png_ptr, buf, (png_size_t)2);
1072 }
1073 png_write_chunk_end(png_ptr);
1074 }
1075 #endif
1077 #if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \
1078 defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
1079 /* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification,
1080 * and if invalid, correct the keyword rather than discarding the entire
1081 * chunk. The PNG 1.0 specification requires keywords 1-79 characters in
1082 * length, forbids leading or trailing whitespace, multiple internal spaces,
1083 * and the non-break space (0x80) from ISO 8859-1. Returns keyword length.
1084 *
1085 * The new_key is allocated to hold the corrected keyword and must be freed
1086 * by the calling routine. This avoids problems with trying to write to
1087 * static keywords without having to have duplicate copies of the strings.
1088 */
1089 png_size_t /* PRIVATE */
1090 png_check_keyword(png_structp png_ptr, png_charp key, png_charpp new_key)
1091 {
1092 png_size_t key_len;
1093 png_charp kp, dp;
1094 int kflag;
1095 int kwarn=0;
1097 png_debug(1, "in png_check_keyword\n");
1098 *new_key = NULL;
1100 if (key == NULL || (key_len = png_strlen(key)) == 0)
1101 {
1102 png_warning(png_ptr, "zero length keyword");
1103 return ((png_size_t)0);
1104 }
1106 png_debug1(2, "Keyword to be checked is '%s'\n", key);
1108 *new_key = (png_charp)png_malloc(png_ptr, (png_uint_32)(key_len + 2));
1110 /* Replace non-printing characters with a blank and print a warning */
1111 for (kp = key, dp = *new_key; *kp != '\0'; kp++, dp++)
1112 {
1113 if (*kp < 0x20 || (*kp > 0x7E && (png_byte)*kp < 0xA1))
1114 {
1115 #if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
1116 char msg[40];
1118 sprintf(msg, "invalid keyword character 0x%02X", *kp);
1119 png_warning(png_ptr, msg);
1120 #else
1121 png_warning(png_ptr, "invalid character in keyword");
1122 #endif
1123 *dp = ' ';
1124 }
1125 else
1126 {
1127 *dp = *kp;
1128 }
1129 }
1130 *dp = '\0';
1132 /* Remove any trailing white space. */
1133 kp = *new_key + key_len - 1;
1134 if (*kp == ' ')
1135 {
1136 png_warning(png_ptr, "trailing spaces removed from keyword");
1138 while (*kp == ' ')
1139 {
1140 *(kp--) = '\0';
1141 key_len--;
1142 }
1143 }
1145 /* Remove any leading white space. */
1146 kp = *new_key;
1147 if (*kp == ' ')
1148 {
1149 png_warning(png_ptr, "leading spaces removed from keyword");
1151 while (*kp == ' ')
1152 {
1153 kp++;
1154 key_len--;
1155 }
1156 }
1158 png_debug1(2, "Checking for multiple internal spaces in '%s'\n", kp);
1160 /* Remove multiple internal spaces. */
1161 for (kflag = 0, dp = *new_key; *kp != '\0'; kp++)
1162 {
1163 if (*kp == ' ' && kflag == 0)
1164 {
1165 *(dp++) = *kp;
1166 kflag = 1;
1167 }
1168 else if (*kp == ' ')
1169 {
1170 key_len--;
1171 kwarn=1;
1172 }
1173 else
1174 {
1175 *(dp++) = *kp;
1176 kflag = 0;
1177 }
1178 }
1179 *dp = '\0';
1180 if(kwarn)
1181 png_warning(png_ptr, "extra interior spaces removed from keyword");
1183 if (key_len == 0)
1184 {
1185 png_free(png_ptr, *new_key);
1186 *new_key=NULL;
1187 png_warning(png_ptr, "Zero length keyword");
1188 }
1190 if (key_len > 79)
1191 {
1192 png_warning(png_ptr, "keyword length must be 1 - 79 characters");
1193 new_key[79] = '\0';
1194 key_len = 79;
1195 }
1197 return (key_len);
1198 }
1199 #endif
1201 #if defined(PNG_WRITE_tEXt_SUPPORTED)
1202 /* write a tEXt chunk */
1203 void /* PRIVATE */
1204 png_write_tEXt(png_structp png_ptr, png_charp key, png_charp text,
1205 png_size_t text_len)
1206 {
1207 #ifdef PNG_USE_LOCAL_ARRAYS
1208 PNG_tEXt;
1209 #endif
1210 png_size_t key_len;
1211 png_charp new_key;
1213 png_debug(1, "in png_write_tEXt\n");
1214 if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0)
1215 {
1216 png_warning(png_ptr, "Empty keyword in tEXt chunk");
1217 return;
1218 }
1220 if (text == NULL || *text == '\0')
1221 text_len = 0;
1222 else
1223 text_len = png_strlen(text);
1225 /* make sure we include the 0 after the key */
1226 png_write_chunk_start(png_ptr, (png_bytep)png_tEXt, (png_uint_32)key_len+text_len+1);
1227 /*
1228 * We leave it to the application to meet PNG-1.0 requirements on the
1229 * contents of the text. PNG-1.0 through PNG-1.2 discourage the use of
1230 * any non-Latin-1 characters except for NEWLINE. ISO PNG will forbid them.
1231 * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1232 */
1233 png_write_chunk_data(png_ptr, (png_bytep)new_key, key_len + 1);
1234 if (text_len)
1235 png_write_chunk_data(png_ptr, (png_bytep)text, text_len);
1237 png_write_chunk_end(png_ptr);
1238 png_free(png_ptr, new_key);
1239 }
1240 #endif
1242 #if defined(PNG_WRITE_zTXt_SUPPORTED)
1243 /* write a compressed text chunk */
1244 void /* PRIVATE */
1245 png_write_zTXt(png_structp png_ptr, png_charp key, png_charp text,
1246 png_size_t text_len, int compression)
1247 {
1248 #ifdef PNG_USE_LOCAL_ARRAYS
1249 PNG_zTXt;
1250 #endif
1251 png_size_t key_len;
1252 char buf[1];
1253 png_charp new_key;
1254 compression_state comp;
1256 png_debug(1, "in png_write_zTXt\n");
1258 if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0)
1259 {
1260 png_warning(png_ptr, "Empty keyword in zTXt chunk");
1261 return;
1262 }
1264 if (text == NULL || *text == '\0' || compression==PNG_TEXT_COMPRESSION_NONE)
1265 {
1266 png_write_tEXt(png_ptr, new_key, text, (png_size_t)0);
1267 png_free(png_ptr, new_key);
1268 return;
1269 }
1271 text_len = png_strlen(text);
1273 png_free(png_ptr, new_key);
1275 /* compute the compressed data; do it now for the length */
1276 text_len = png_text_compress(png_ptr, text, text_len, compression,
1277 &comp);
1279 /* write start of chunk */
1280 png_write_chunk_start(png_ptr, (png_bytep)png_zTXt, (png_uint_32)
1281 (key_len+text_len+2));
1282 /* write key */
1283 png_write_chunk_data(png_ptr, (png_bytep)key, key_len + 1);
1284 buf[0] = (png_byte)compression;
1285 /* write compression */
1286 png_write_chunk_data(png_ptr, (png_bytep)buf, (png_size_t)1);
1287 /* write the compressed data */
1288 png_write_compressed_data_out(png_ptr, &comp);
1290 /* close the chunk */
1291 png_write_chunk_end(png_ptr);
1292 }
1293 #endif
1295 #if defined(PNG_WRITE_iTXt_SUPPORTED)
1296 /* write an iTXt chunk */
1297 void /* PRIVATE */
1298 png_write_iTXt(png_structp png_ptr, int compression, png_charp key,
1299 png_charp lang, png_charp lang_key, png_charp text)
1300 {
1301 #ifdef PNG_USE_LOCAL_ARRAYS
1302 PNG_iTXt;
1303 #endif
1304 png_size_t lang_len, key_len, lang_key_len, text_len;
1305 png_charp new_lang, new_key;
1306 png_byte cbuf[2];
1307 compression_state comp;
1309 png_debug(1, "in png_write_iTXt\n");
1311 if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0)
1312 {
1313 png_warning(png_ptr, "Empty keyword in iTXt chunk");
1314 return;
1315 }
1316 if (lang == NULL || (lang_len = png_check_keyword(png_ptr, lang,
1317 &new_lang))==0)
1318 {
1319 png_warning(png_ptr, "Empty language field in iTXt chunk");
1320 return;
1321 }
1322 lang_key_len = png_strlen(lang_key);
1323 text_len = png_strlen(text);
1325 if (text == NULL || *text == '\0')
1326 text_len = 0;
1328 /* compute the compressed data; do it now for the length */
1329 text_len = png_text_compress(png_ptr, text, text_len, compression-2,
1330 &comp);
1332 /* make sure we include the compression flag, the compression byte,
1333 * and the NULs after the key, lang, and lang_key parts */
1335 png_write_chunk_start(png_ptr, (png_bytep)png_iTXt,
1336 (png_uint_32)(
1337 5 /* comp byte, comp flag, terminators for key, lang and lang_key */
1338 + key_len
1339 + lang_len
1340 + lang_key_len
1341 + text_len));
1343 /*
1344 * We leave it to the application to meet PNG-1.0 requirements on the
1345 * contents of the text. PNG-1.0 through PNG-1.2 discourage the use of
1346 * any non-Latin-1 characters except for NEWLINE. ISO PNG will forbid them.
1347 * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1348 */
1349 png_write_chunk_data(png_ptr, (png_bytep)new_key, key_len + 1);
1351 /* set the compression flag */
1352 if (compression == PNG_ITXT_COMPRESSION_NONE || \
1353 compression == PNG_TEXT_COMPRESSION_NONE)
1354 cbuf[0] = 0;
1355 else /* compression == PNG_ITXT_COMPRESSION_zTXt */
1356 cbuf[0] = 1;
1357 /* set the compression method */
1358 cbuf[1] = 0;
1359 png_write_chunk_data(png_ptr, cbuf, 2);
1361 png_write_chunk_data(png_ptr, (png_bytep)new_lang, lang_len + 1);
1362 png_write_chunk_data(png_ptr, (png_bytep)lang_key, lang_key_len+1);
1363 png_write_chunk_data(png_ptr, '\0', 1);
1365 png_write_compressed_data_out(png_ptr, &comp);
1367 png_write_chunk_end(png_ptr);
1368 png_free(png_ptr, new_key);
1369 png_free(png_ptr, new_lang);
1370 }
1371 #endif
1373 #if defined(PNG_WRITE_oFFs_SUPPORTED)
1374 /* write the oFFs chunk */
1375 void /* PRIVATE */
1376 png_write_oFFs(png_structp png_ptr, png_uint_32 x_offset,
1377 png_uint_32 y_offset,
1378 int unit_type)
1379 {
1380 #ifdef PNG_USE_LOCAL_ARRAYS
1381 PNG_oFFs;
1382 #endif
1383 png_byte buf[9];
1385 png_debug(1, "in png_write_oFFs\n");
1386 if (unit_type >= PNG_OFFSET_LAST)
1387 png_warning(png_ptr, "Unrecognized unit type for oFFs chunk");
1389 png_save_uint_32(buf, x_offset);
1390 png_save_uint_32(buf + 4, y_offset);
1391 buf[8] = (png_byte)unit_type;
1393 png_write_chunk(png_ptr, (png_bytep)png_oFFs, buf, (png_size_t)9);
1394 }
1395 #endif
1397 #if defined(PNG_WRITE_pCAL_SUPPORTED)
1398 /* write the pCAL chunk (described in the PNG extensions document) */
1399 void /* PRIVATE */
1400 png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
1401 png_int_32 X1, int type, int nparams, png_charp units, png_charpp params)
1402 {
1403 #ifdef PNG_USE_LOCAL_ARRAYS
1404 PNG_pCAL;
1405 #endif
1406 png_size_t purpose_len, units_len, total_len;
1407 png_uint_32p params_len;
1408 png_byte buf[10];
1409 png_charp new_purpose;
1410 int i;
1412 png_debug1(1, "in png_write_pCAL (%d parameters)\n", nparams);
1413 if (type >= PNG_EQUATION_LAST)
1414 png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");
1416 purpose_len = png_check_keyword(png_ptr, purpose, &new_purpose) + 1;
1417 png_debug1(3, "pCAL purpose length = %d\n", purpose_len);
1418 units_len = png_strlen(units) + (nparams == 0 ? 0 : 1);
1419 png_debug1(3, "pCAL units length = %d\n", units_len);
1420 total_len = purpose_len + units_len + 10;
1422 params_len = (png_uint_32p)png_malloc(png_ptr, (png_uint_32)(nparams
1423 *sizeof(png_uint_32)));
1425 /* Find the length of each parameter, making sure we don't count the
1426 null terminator for the last parameter. */
1427 for (i = 0; i < nparams; i++)
1428 {
1429 params_len[i] = png_strlen(params[i]) + (i == nparams - 1 ? 0 : 1);
1430 png_debug2(3, "pCAL parameter %d length = %lu\n", i, params_len[i]);
1431 total_len += (png_size_t)params_len[i];
1432 }
1434 png_debug1(3, "pCAL total length = %d\n", total_len);
1435 png_write_chunk_start(png_ptr, (png_bytep)png_pCAL, (png_uint_32)total_len);
1436 png_write_chunk_data(png_ptr, (png_bytep)new_purpose, purpose_len);
1437 png_save_int_32(buf, X0);
1438 png_save_int_32(buf + 4, X1);
1439 buf[8] = (png_byte)type;
1440 buf[9] = (png_byte)nparams;
1441 png_write_chunk_data(png_ptr, buf, (png_size_t)10);
1442 png_write_chunk_data(png_ptr, (png_bytep)units, (png_size_t)units_len);
1444 png_free(png_ptr, new_purpose);
1446 for (i = 0; i < nparams; i++)
1447 {
1448 png_write_chunk_data(png_ptr, (png_bytep)params[i],
1449 (png_size_t)params_len[i]);
1450 }
1452 png_free(png_ptr, params_len);
1453 png_write_chunk_end(png_ptr);
1454 }
1455 #endif
1457 #if defined(PNG_WRITE_sCAL_SUPPORTED)
1458 /* write the sCAL chunk */
1459 #if defined(PNG_FLOATING_POINT_SUPPORTED) && !defined(PNG_NO_STDIO)
1460 void /* PRIVATE */
1461 png_write_sCAL(png_structp png_ptr, int unit, double width,double height)
1462 {
1463 #ifdef PNG_USE_LOCAL_ARRAYS
1464 PNG_sCAL;
1465 #endif
1466 png_size_t total_len;
1467 char wbuf[32], hbuf[32];
1469 png_debug(1, "in png_write_sCAL\n");
1471 #if defined(_WIN32_WCE)
1472 /* sprintf() function is not supported on WindowsCE */
1473 {
1474 wchar_t wc_buf[32];
1475 swprintf(wc_buf, TEXT("%12.12e"), width);
1476 WideCharToMultiByte(CP_ACP, 0, wc_buf, -1, wbuf, 32, NULL, NULL);
1477 swprintf(wc_buf, TEXT("%12.12e"), height);
1478 WideCharToMultiByte(CP_ACP, 0, wc_buf, -1, hbuf, 32, NULL, NULL);
1479 }
1480 #else
1481 sprintf(wbuf, "%12.12e", width);
1482 sprintf(hbuf, "%12.12e", height);
1483 #endif
1484 total_len = 1 + png_strlen(wbuf)+1 + png_strlen(hbuf);
1486 png_debug1(3, "sCAL total length = %d\n", total_len);
1487 png_write_chunk_start(png_ptr, (png_bytep)png_sCAL, (png_uint_32)total_len);
1488 png_write_chunk_data(png_ptr, (png_bytep)&unit, 1);
1489 png_write_chunk_data(png_ptr, (png_bytep)wbuf, strlen(wbuf)+1);
1490 png_write_chunk_data(png_ptr, (png_bytep)hbuf, strlen(hbuf));
1492 png_write_chunk_end(png_ptr);
1493 }
1494 #else
1495 #ifdef PNG_FIXED_POINT_SUPPORTED
1496 void /* PRIVATE */
1497 png_write_sCAL_s(png_structp png_ptr, int unit, png_charp width,
1498 png_charp height)
1499 {
1500 #ifdef PNG_USE_LOCAL_ARRAYS
1501 PNG_sCAL;
1502 #endif
1503 png_size_t total_len;
1504 char wbuf[32], hbuf[32];
1506 png_debug(1, "in png_write_sCAL_s\n");
1508 strcpy(wbuf,(const char *)width);
1509 strcpy(hbuf,(const char *)height);
1510 total_len = 1 + png_strlen(wbuf)+1 + png_strlen(hbuf);
1512 png_debug1(3, "sCAL total length = %d\n", total_len);
1513 png_write_chunk_start(png_ptr, (png_bytep)png_sCAL, (png_uint_32)total_len);
1514 png_write_chunk_data(png_ptr, (png_bytep)&unit, 1);
1515 png_write_chunk_data(png_ptr, (png_bytep)wbuf, strlen(wbuf)+1);
1516 png_write_chunk_data(png_ptr, (png_bytep)hbuf, strlen(hbuf));
1518 png_write_chunk_end(png_ptr);
1519 }
1520 #endif
1521 #endif
1522 #endif
1524 #if defined(PNG_WRITE_pHYs_SUPPORTED)
1525 /* write the pHYs chunk */
1526 void /* PRIVATE */
1527 png_write_pHYs(png_structp png_ptr, png_uint_32 x_pixels_per_unit,
1528 png_uint_32 y_pixels_per_unit,
1529 int unit_type)
1530 {
1531 #ifdef PNG_USE_LOCAL_ARRAYS
1532 PNG_pHYs;
1533 #endif
1534 png_byte buf[9];
1536 png_debug(1, "in png_write_pHYs\n");
1537 if (unit_type >= PNG_RESOLUTION_LAST)
1538 png_warning(png_ptr, "Unrecognized unit type for pHYs chunk");
1540 png_save_uint_32(buf, x_pixels_per_unit);
1541 png_save_uint_32(buf + 4, y_pixels_per_unit);
1542 buf[8] = (png_byte)unit_type;
1544 png_write_chunk(png_ptr, (png_bytep)png_pHYs, buf, (png_size_t)9);
1545 }
1546 #endif
1548 #if defined(PNG_WRITE_tIME_SUPPORTED)
1549 /* Write the tIME chunk. Use either png_convert_from_struct_tm()
1550 * or png_convert_from_time_t(), or fill in the structure yourself.
1551 */
1552 void /* PRIVATE */
1553 png_write_tIME(png_structp png_ptr, png_timep mod_time)
1554 {
1555 #ifdef PNG_USE_LOCAL_ARRAYS
1556 PNG_tIME;
1557 #endif
1558 png_byte buf[7];
1560 png_debug(1, "in png_write_tIME\n");
1561 if (mod_time->month > 12 || mod_time->month < 1 ||
1562 mod_time->day > 31 || mod_time->day < 1 ||
1563 mod_time->hour > 23 || mod_time->second > 60)
1564 {
1565 png_warning(png_ptr, "Invalid time specified for tIME chunk");
1566 return;
1567 }
1569 png_save_uint_16(buf, mod_time->year);
1570 buf[2] = mod_time->month;
1571 buf[3] = mod_time->day;
1572 buf[4] = mod_time->hour;
1573 buf[5] = mod_time->minute;
1574 buf[6] = mod_time->second;
1576 png_write_chunk(png_ptr, (png_bytep)png_tIME, buf, (png_size_t)7);
1577 }
1578 #endif
1580 /* initializes the row writing capability of libpng */
1581 void /* PRIVATE */
1582 png_write_start_row(png_structp png_ptr)
1583 {
1584 #ifdef PNG_USE_LOCAL_ARRAYS
1585 /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1587 /* start of interlace block */
1588 int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
1590 /* offset to next interlace block */
1591 int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
1593 /* start of interlace block in the y direction */
1594 int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
1596 /* offset to next interlace block in the y direction */
1597 int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
1598 #endif
1600 png_size_t buf_size;
1602 png_debug(1, "in png_write_start_row\n");
1603 buf_size = (png_size_t)(((png_ptr->width * png_ptr->usr_channels *
1604 png_ptr->usr_bit_depth + 7) >> 3) + 1);
1606 /* set up row buffer */
1607 png_ptr->row_buf = (png_bytep)png_malloc(png_ptr, (png_uint_32)buf_size);
1608 png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE;
1610 /* set up filtering buffer, if using this filter */
1611 if (png_ptr->do_filter & PNG_FILTER_SUB)
1612 {
1613 png_ptr->sub_row = (png_bytep)png_malloc(png_ptr,
1614 (png_ptr->rowbytes + 1));
1615 png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
1616 }
1618 /* We only need to keep the previous row if we are using one of these. */
1619 if (png_ptr->do_filter & (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH))
1620 {
1621 /* set up previous row buffer */
1622 png_ptr->prev_row = (png_bytep)png_malloc(png_ptr, (png_uint_32)buf_size);
1623 png_memset(png_ptr->prev_row, 0, buf_size);
1625 if (png_ptr->do_filter & PNG_FILTER_UP)
1626 {
1627 png_ptr->up_row = (png_bytep )png_malloc(png_ptr,
1628 (png_ptr->rowbytes + 1));
1629 png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;
1630 }
1632 if (png_ptr->do_filter & PNG_FILTER_AVG)
1633 {
1634 png_ptr->avg_row = (png_bytep)png_malloc(png_ptr,
1635 (png_ptr->rowbytes + 1));
1636 png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;
1637 }
1639 if (png_ptr->do_filter & PNG_FILTER_PAETH)
1640 {
1641 png_ptr->paeth_row = (png_bytep )png_malloc(png_ptr,
1642 (png_ptr->rowbytes + 1));
1643 png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
1644 }
1645 }
1647 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
1648 /* if interlaced, we need to set up width and height of pass */
1649 if (png_ptr->interlaced)
1650 {
1651 if (!(png_ptr->transformations & PNG_INTERLACE))
1652 {
1653 png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
1654 png_pass_ystart[0]) / png_pass_yinc[0];
1655 png_ptr->usr_width = (png_ptr->width + png_pass_inc[0] - 1 -
1656 png_pass_start[0]) / png_pass_inc[0];
1657 }
1658 else
1659 {
1660 png_ptr->num_rows = png_ptr->height;
1661 png_ptr->usr_width = png_ptr->width;
1662 }
1663 }
1664 else
1665 #endif
1666 {
1667 png_ptr->num_rows = png_ptr->height;
1668 png_ptr->usr_width = png_ptr->width;
1669 }
1670 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1671 png_ptr->zstream.next_out = png_ptr->zbuf;
1672 }
1674 /* Internal use only. Called when finished processing a row of data. */
1675 void /* PRIVATE */
1676 png_write_finish_row(png_structp png_ptr)
1677 {
1678 #ifdef PNG_USE_LOCAL_ARRAYS
1679 /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1681 /* start of interlace block */
1682 int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
1684 /* offset to next interlace block */
1685 int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
1687 /* start of interlace block in the y direction */
1688 int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
1690 /* offset to next interlace block in the y direction */
1691 int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
1692 #endif
1694 int ret;
1696 png_debug(1, "in png_write_finish_row\n");
1697 /* next row */
1698 png_ptr->row_number++;
1700 /* see if we are done */
1701 if (png_ptr->row_number < png_ptr->num_rows)
1702 return;
1704 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
1705 /* if interlaced, go to next pass */
1706 if (png_ptr->interlaced)
1707 {
1708 png_ptr->row_number = 0;
1709 if (png_ptr->transformations & PNG_INTERLACE)
1710 {
1711 png_ptr->pass++;
1712 }
1713 else
1714 {
1715 /* loop until we find a non-zero width or height pass */
1716 do
1717 {
1718 png_ptr->pass++;
1719 if (png_ptr->pass >= 7)
1720 break;
1721 png_ptr->usr_width = (png_ptr->width +
1722 png_pass_inc[png_ptr->pass] - 1 -
1723 png_pass_start[png_ptr->pass]) /
1724 png_pass_inc[png_ptr->pass];
1725 png_ptr->num_rows = (png_ptr->height +
1726 png_pass_yinc[png_ptr->pass] - 1 -
1727 png_pass_ystart[png_ptr->pass]) /
1728 png_pass_yinc[png_ptr->pass];
1729 if (png_ptr->transformations & PNG_INTERLACE)
1730 break;
1731 } while (png_ptr->usr_width == 0 || png_ptr->num_rows == 0);
1733 }
1735 /* reset the row above the image for the next pass */
1736 if (png_ptr->pass < 7)
1737 {
1738 if (png_ptr->prev_row != NULL)
1739 png_memset(png_ptr->prev_row, 0,
1740 (png_size_t) (((png_uint_32)png_ptr->usr_channels *
1741 (png_uint_32)png_ptr->usr_bit_depth *
1742 png_ptr->width + 7) >> 3) + 1);
1743 return;
1744 }
1745 }
1746 #endif
1748 /* if we get here, we've just written the last row, so we need
1749 to flush the compressor */
1750 do
1751 {
1752 /* tell the compressor we are done */
1753 ret = deflate(&png_ptr->zstream, Z_FINISH);
1754 /* check for an error */
1755 if (ret == Z_OK)
1756 {
1757 /* check to see if we need more room */
1758 if (!(png_ptr->zstream.avail_out))
1759 {
1760 png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
1761 png_ptr->zstream.next_out = png_ptr->zbuf;
1762 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1763 }
1764 }
1765 else if (ret != Z_STREAM_END)
1766 {
1767 if (png_ptr->zstream.msg != NULL)
1768 png_error(png_ptr, png_ptr->zstream.msg);
1769 else
1770 png_error(png_ptr, "zlib error");
1771 }
1772 } while (ret != Z_STREAM_END);
1774 /* write any extra space */
1775 if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
1776 {
1777 png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size -
1778 png_ptr->zstream.avail_out);
1779 }
1781 deflateReset(&png_ptr->zstream);
1782 }
1784 #if defined(PNG_WRITE_INTERLACING_SUPPORTED)
1785 /* Pick out the correct pixels for the interlace pass.
1786 * The basic idea here is to go through the row with a source
1787 * pointer and a destination pointer (sp and dp), and copy the
1788 * correct pixels for the pass. As the row gets compacted,
1789 * sp will always be >= dp, so we should never overwrite anything.
1790 * See the default: case for the easiest code to understand.
1791 */
1792 void /* PRIVATE */
1793 png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
1794 {
1795 #ifdef PNG_USE_LOCAL_ARRAYS
1796 /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1798 /* start of interlace block */
1799 int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
1801 /* offset to next interlace block */
1802 int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
1803 #endif
1805 png_debug(1, "in png_do_write_interlace\n");
1806 /* we don't have to do anything on the last pass (6) */
1807 #if defined(PNG_USELESS_TESTS_SUPPORTED)
1808 if (row != NULL && row_info != NULL && pass < 6)
1809 #else
1810 if (pass < 6)
1811 #endif
1812 {
1813 /* each pixel depth is handled separately */
1814 switch (row_info->pixel_depth)
1815 {
1816 case 1:
1817 {
1818 png_bytep sp;
1819 png_bytep dp;
1820 int shift;
1821 int d;
1822 int value;
1823 png_uint_32 i;
1824 png_uint_32 row_width = row_info->width;
1826 dp = row;
1827 d = 0;
1828 shift = 7;
1829 for (i = png_pass_start[pass]; i < row_width;
1830 i += png_pass_inc[pass])
1831 {
1832 sp = row + (png_size_t)(i >> 3);
1833 value = (int)(*sp >> (7 - (int)(i & 0x07))) & 0x01;
1834 d |= (value << shift);
1836 if (shift == 0)
1837 {
1838 shift = 7;
1839 *dp++ = (png_byte)d;
1840 d = 0;
1841 }
1842 else
1843 shift--;
1845 }
1846 if (shift != 7)
1847 *dp = (png_byte)d;
1848 break;
1849 }
1850 case 2:
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 shift = 6;
1862 d = 0;
1863 for (i = png_pass_start[pass]; i < row_width;
1864 i += png_pass_inc[pass])
1865 {
1866 sp = row + (png_size_t)(i >> 2);
1867 value = (*sp >> ((3 - (int)(i & 0x03)) << 1)) & 0x03;
1868 d |= (value << shift);
1870 if (shift == 0)
1871 {
1872 shift = 6;
1873 *dp++ = (png_byte)d;
1874 d = 0;
1875 }
1876 else
1877 shift -= 2;
1878 }
1879 if (shift != 6)
1880 *dp = (png_byte)d;
1881 break;
1882 }
1883 case 4:
1884 {
1885 png_bytep sp;
1886 png_bytep dp;
1887 int shift;
1888 int d;
1889 int value;
1890 png_uint_32 i;
1891 png_uint_32 row_width = row_info->width;
1893 dp = row;
1894 shift = 4;
1895 d = 0;
1896 for (i = png_pass_start[pass]; i < row_width;
1897 i += png_pass_inc[pass])
1898 {
1899 sp = row + (png_size_t)(i >> 1);
1900 value = (*sp >> ((1 - (int)(i & 0x01)) << 2)) & 0x0f;
1901 d |= (value << shift);
1903 if (shift == 0)
1904 {
1905 shift = 4;
1906 *dp++ = (png_byte)d;
1907 d = 0;
1908 }
1909 else
1910 shift -= 4;
1911 }
1912 if (shift != 4)
1913 *dp = (png_byte)d;
1914 break;
1915 }
1916 default:
1917 {
1918 png_bytep sp;
1919 png_bytep dp;
1920 png_uint_32 i;
1921 png_uint_32 row_width = row_info->width;
1922 png_size_t pixel_bytes;
1924 /* start at the beginning */
1925 dp = row;
1926 /* find out how many bytes each pixel takes up */
1927 pixel_bytes = (row_info->pixel_depth >> 3);
1928 /* loop through the row, only looking at the pixels that
1929 matter */
1930 for (i = png_pass_start[pass]; i < row_width;
1931 i += png_pass_inc[pass])
1932 {
1933 /* find out where the original pixel is */
1934 sp = row + (png_size_t)i * pixel_bytes;
1935 /* move the pixel */
1936 if (dp != sp)
1937 png_memcpy(dp, sp, pixel_bytes);
1938 /* next pixel */
1939 dp += pixel_bytes;
1940 }
1941 break;
1942 }
1943 }
1944 /* set new row width */
1945 row_info->width = (row_info->width +
1946 png_pass_inc[pass] - 1 -
1947 png_pass_start[pass]) /
1948 png_pass_inc[pass];
1949 row_info->rowbytes = ((row_info->width *
1950 row_info->pixel_depth + 7) >> 3);
1951 }
1952 }
1953 #endif
1955 /* This filters the row, chooses which filter to use, if it has not already
1956 * been specified by the application, and then writes the row out with the
1957 * chosen filter.
1958 */
1959 #define PNG_MAXSUM (~((png_uint_32)0) >> 1)
1960 #define PNG_HISHIFT 10
1961 #define PNG_LOMASK ((png_uint_32)0xffffL)
1962 #define PNG_HIMASK ((png_uint_32)(~PNG_LOMASK >> PNG_HISHIFT))
1963 void /* PRIVATE */
1964 png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
1965 {
1966 png_bytep prev_row, best_row, row_buf;
1967 png_uint_32 mins, bpp;
1968 png_byte filter_to_do = png_ptr->do_filter;
1969 png_uint_32 row_bytes = row_info->rowbytes;
1970 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
1971 int num_p_filters = (int)png_ptr->num_prev_filters;
1972 #endif
1974 png_debug(1, "in png_write_find_filter\n");
1975 /* find out how many bytes offset each pixel is */
1976 bpp = (row_info->pixel_depth + 7) / 8;
1978 prev_row = png_ptr->prev_row;
1979 best_row = row_buf = png_ptr->row_buf;
1980 mins = PNG_MAXSUM;
1982 /* The prediction method we use is to find which method provides the
1983 * smallest value when summing the absolute values of the distances
1984 * from zero, using anything >= 128 as negative numbers. This is known
1985 * as the "minimum sum of absolute differences" heuristic. Other
1986 * heuristics are the "weighted minimum sum of absolute differences"
1987 * (experimental and can in theory improve compression), and the "zlib
1988 * predictive" method (not implemented yet), which does test compressions
1989 * of lines using different filter methods, and then chooses the
1990 * (series of) filter(s) that give minimum compressed data size (VERY
1991 * computationally expensive).
1992 *
1993 * GRR 980525: consider also
1994 * (1) minimum sum of absolute differences from running average (i.e.,
1995 * keep running sum of non-absolute differences & count of bytes)
1996 * [track dispersion, too? restart average if dispersion too large?]
1997 * (1b) minimum sum of absolute differences from sliding average, probably
1998 * with window size <= deflate window (usually 32K)
1999 * (2) minimum sum of squared differences from zero or running average
2000 * (i.e., ~ root-mean-square approach)
2001 */
2004 /* We don't need to test the 'no filter' case if this is the only filter
2005 * that has been chosen, as it doesn't actually do anything to the data.
2006 */
2007 if ((filter_to_do & PNG_FILTER_NONE) &&
2008 filter_to_do != PNG_FILTER_NONE)
2009 {
2010 png_bytep rp;
2011 png_uint_32 sum = 0;
2012 png_uint_32 i;
2013 int v;
2015 for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
2016 {
2017 v = *rp;
2018 sum += (v < 128) ? v : 256 - v;
2019 }
2021 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2022 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2023 {
2024 png_uint_32 sumhi, sumlo;
2025 int j;
2026 sumlo = sum & PNG_LOMASK;
2027 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; /* Gives us some footroom */
2029 /* Reduce the sum if we match any of the previous rows */
2030 for (j = 0; j < num_p_filters; j++)
2031 {
2032 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
2033 {
2034 sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2035 PNG_WEIGHT_SHIFT;
2036 sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2037 PNG_WEIGHT_SHIFT;
2038 }
2039 }
2041 /* Factor in the cost of this filter (this is here for completeness,
2042 * but it makes no sense to have a "cost" for the NONE filter, as
2043 * it has the minimum possible computational cost - none).
2044 */
2045 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
2046 PNG_COST_SHIFT;
2047 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
2048 PNG_COST_SHIFT;
2050 if (sumhi > PNG_HIMASK)
2051 sum = PNG_MAXSUM;
2052 else
2053 sum = (sumhi << PNG_HISHIFT) + sumlo;
2054 }
2055 #endif
2056 mins = sum;
2057 }
2059 /* sub filter */
2060 if (filter_to_do == PNG_FILTER_SUB)
2061 /* it's the only filter so no testing is needed */
2062 {
2063 png_bytep rp, lp, dp;
2064 png_uint_32 i;
2065 for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
2066 i++, rp++, dp++)
2067 {
2068 *dp = *rp;
2069 }
2070 for (lp = row_buf + 1; i < row_bytes;
2071 i++, rp++, lp++, dp++)
2072 {
2073 *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
2074 }
2075 best_row = png_ptr->sub_row;
2076 }
2078 else if (filter_to_do & PNG_FILTER_SUB)
2079 {
2080 png_bytep rp, dp, lp;
2081 png_uint_32 sum = 0, lmins = mins;
2082 png_uint_32 i;
2083 int v;
2085 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2086 /* We temporarily increase the "minimum sum" by the factor we
2087 * would reduce the sum of this filter, so that we can do the
2088 * early exit comparison without scaling the sum each time.
2089 */
2090 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2091 {
2092 int j;
2093 png_uint_32 lmhi, lmlo;
2094 lmlo = lmins & PNG_LOMASK;
2095 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2097 for (j = 0; j < num_p_filters; j++)
2098 {
2099 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
2100 {
2101 lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2102 PNG_WEIGHT_SHIFT;
2103 lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2104 PNG_WEIGHT_SHIFT;
2105 }
2106 }
2108 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2109 PNG_COST_SHIFT;
2110 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2111 PNG_COST_SHIFT;
2113 if (lmhi > PNG_HIMASK)
2114 lmins = PNG_MAXSUM;
2115 else
2116 lmins = (lmhi << PNG_HISHIFT) + lmlo;
2117 }
2118 #endif
2120 for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
2121 i++, rp++, dp++)
2122 {
2123 v = *dp = *rp;
2125 sum += (v < 128) ? v : 256 - v;
2126 }
2127 for (lp = row_buf + 1; i < row_info->rowbytes;
2128 i++, rp++, lp++, dp++)
2129 {
2130 v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
2132 sum += (v < 128) ? v : 256 - v;
2134 if (sum > lmins) /* We are already worse, don't continue. */
2135 break;
2136 }
2138 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2139 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2140 {
2141 int j;
2142 png_uint_32 sumhi, sumlo;
2143 sumlo = sum & PNG_LOMASK;
2144 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2146 for (j = 0; j < num_p_filters; j++)
2147 {
2148 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
2149 {
2150 sumlo = (sumlo * png_ptr->inv_filter_weights[j]) >>
2151 PNG_WEIGHT_SHIFT;
2152 sumhi = (sumhi * png_ptr->inv_filter_weights[j]) >>
2153 PNG_WEIGHT_SHIFT;
2154 }
2155 }
2157 sumlo = (sumlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2158 PNG_COST_SHIFT;
2159 sumhi = (sumhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2160 PNG_COST_SHIFT;
2162 if (sumhi > PNG_HIMASK)
2163 sum = PNG_MAXSUM;
2164 else
2165 sum = (sumhi << PNG_HISHIFT) + sumlo;
2166 }
2167 #endif
2169 if (sum < mins)
2170 {
2171 mins = sum;
2172 best_row = png_ptr->sub_row;
2173 }
2174 }
2176 /* up filter */
2177 if (filter_to_do == PNG_FILTER_UP)
2178 {
2179 png_bytep rp, dp, pp;
2180 png_uint_32 i;
2182 for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
2183 pp = prev_row + 1; i < row_bytes;
2184 i++, rp++, pp++, dp++)
2185 {
2186 *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
2187 }
2188 best_row = png_ptr->up_row;
2189 }
2191 else if (filter_to_do & PNG_FILTER_UP)
2192 {
2193 png_bytep rp, dp, pp;
2194 png_uint_32 sum = 0, lmins = mins;
2195 png_uint_32 i;
2196 int v;
2199 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2200 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2201 {
2202 int j;
2203 png_uint_32 lmhi, lmlo;
2204 lmlo = lmins & PNG_LOMASK;
2205 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2207 for (j = 0; j < num_p_filters; j++)
2208 {
2209 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
2210 {
2211 lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2212 PNG_WEIGHT_SHIFT;
2213 lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2214 PNG_WEIGHT_SHIFT;
2215 }
2216 }
2218 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
2219 PNG_COST_SHIFT;
2220 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
2221 PNG_COST_SHIFT;
2223 if (lmhi > PNG_HIMASK)
2224 lmins = PNG_MAXSUM;
2225 else
2226 lmins = (lmhi << PNG_HISHIFT) + lmlo;
2227 }
2228 #endif
2230 for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
2231 pp = prev_row + 1; i < row_bytes; i++)
2232 {
2233 v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2235 sum += (v < 128) ? v : 256 - v;
2237 if (sum > lmins) /* We are already worse, don't continue. */
2238 break;
2239 }
2241 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2242 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2243 {
2244 int j;
2245 png_uint_32 sumhi, sumlo;
2246 sumlo = sum & PNG_LOMASK;
2247 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2249 for (j = 0; j < num_p_filters; j++)
2250 {
2251 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
2252 {
2253 sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2254 PNG_WEIGHT_SHIFT;
2255 sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2256 PNG_WEIGHT_SHIFT;
2257 }
2258 }
2260 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
2261 PNG_COST_SHIFT;
2262 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
2263 PNG_COST_SHIFT;
2265 if (sumhi > PNG_HIMASK)
2266 sum = PNG_MAXSUM;
2267 else
2268 sum = (sumhi << PNG_HISHIFT) + sumlo;
2269 }
2270 #endif
2272 if (sum < mins)
2273 {
2274 mins = sum;
2275 best_row = png_ptr->up_row;
2276 }
2277 }
2279 /* avg filter */
2280 if (filter_to_do == PNG_FILTER_AVG)
2281 {
2282 png_bytep rp, dp, pp, lp;
2283 png_uint_32 i;
2284 for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
2285 pp = prev_row + 1; i < bpp; i++)
2286 {
2287 *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
2288 }
2289 for (lp = row_buf + 1; i < row_bytes; i++)
2290 {
2291 *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
2292 & 0xff);
2293 }
2294 best_row = png_ptr->avg_row;
2295 }
2297 else if (filter_to_do & PNG_FILTER_AVG)
2298 {
2299 png_bytep rp, dp, pp, lp;
2300 png_uint_32 sum = 0, lmins = mins;
2301 png_uint_32 i;
2302 int v;
2304 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2305 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2306 {
2307 int j;
2308 png_uint_32 lmhi, lmlo;
2309 lmlo = lmins & PNG_LOMASK;
2310 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2312 for (j = 0; j < num_p_filters; j++)
2313 {
2314 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_AVG)
2315 {
2316 lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2317 PNG_WEIGHT_SHIFT;
2318 lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2319 PNG_WEIGHT_SHIFT;
2320 }
2321 }
2323 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
2324 PNG_COST_SHIFT;
2325 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
2326 PNG_COST_SHIFT;
2328 if (lmhi > PNG_HIMASK)
2329 lmins = PNG_MAXSUM;
2330 else
2331 lmins = (lmhi << PNG_HISHIFT) + lmlo;
2332 }
2333 #endif
2335 for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
2336 pp = prev_row + 1; i < bpp; i++)
2337 {
2338 v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
2340 sum += (v < 128) ? v : 256 - v;
2341 }
2342 for (lp = row_buf + 1; i < row_bytes; i++)
2343 {
2344 v = *dp++ =
2345 (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) & 0xff);
2347 sum += (v < 128) ? v : 256 - v;
2349 if (sum > lmins) /* We are already worse, don't continue. */
2350 break;
2351 }
2353 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2354 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2355 {
2356 int j;
2357 png_uint_32 sumhi, sumlo;
2358 sumlo = sum & PNG_LOMASK;
2359 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2361 for (j = 0; j < num_p_filters; j++)
2362 {
2363 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
2364 {
2365 sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2366 PNG_WEIGHT_SHIFT;
2367 sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2368 PNG_WEIGHT_SHIFT;
2369 }
2370 }
2372 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
2373 PNG_COST_SHIFT;
2374 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
2375 PNG_COST_SHIFT;
2377 if (sumhi > PNG_HIMASK)
2378 sum = PNG_MAXSUM;
2379 else
2380 sum = (sumhi << PNG_HISHIFT) + sumlo;
2381 }
2382 #endif
2384 if (sum < mins)
2385 {
2386 mins = sum;
2387 best_row = png_ptr->avg_row;
2388 }
2389 }
2391 /* Paeth filter */
2392 if (filter_to_do == PNG_FILTER_PAETH)
2393 {
2394 png_bytep rp, dp, pp, cp, lp;
2395 png_uint_32 i;
2396 for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
2397 pp = prev_row + 1; i < bpp; i++)
2398 {
2399 *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2400 }
2402 for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
2403 {
2404 int a, b, c, pa, pb, pc, p;
2406 b = *pp++;
2407 c = *cp++;
2408 a = *lp++;
2410 p = b - c;
2411 pc = a - c;
2413 #ifdef PNG_USE_ABS
2414 pa = abs(p);
2415 pb = abs(pc);
2416 pc = abs(p + pc);
2417 #else
2418 pa = p < 0 ? -p : p;
2419 pb = pc < 0 ? -pc : pc;
2420 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
2421 #endif
2423 p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
2425 *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
2426 }
2427 best_row = png_ptr->paeth_row;
2428 }
2430 else if (filter_to_do & PNG_FILTER_PAETH)
2431 {
2432 png_bytep rp, dp, pp, cp, lp;
2433 png_uint_32 sum = 0, lmins = mins;
2434 png_uint_32 i;
2435 int v;
2437 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2438 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2439 {
2440 int j;
2441 png_uint_32 lmhi, lmlo;
2442 lmlo = lmins & PNG_LOMASK;
2443 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2445 for (j = 0; j < num_p_filters; j++)
2446 {
2447 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
2448 {
2449 lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2450 PNG_WEIGHT_SHIFT;
2451 lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2452 PNG_WEIGHT_SHIFT;
2453 }
2454 }
2456 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2457 PNG_COST_SHIFT;
2458 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2459 PNG_COST_SHIFT;
2461 if (lmhi > PNG_HIMASK)
2462 lmins = PNG_MAXSUM;
2463 else
2464 lmins = (lmhi << PNG_HISHIFT) + lmlo;
2465 }
2466 #endif
2468 for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
2469 pp = prev_row + 1; i < bpp; i++)
2470 {
2471 v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2473 sum += (v < 128) ? v : 256 - v;
2474 }
2476 for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
2477 {
2478 int a, b, c, pa, pb, pc, p;
2480 b = *pp++;
2481 c = *cp++;
2482 a = *lp++;
2484 #ifndef PNG_SLOW_PAETH
2485 p = b - c;
2486 pc = a - c;
2487 #ifdef PNG_USE_ABS
2488 pa = abs(p);
2489 pb = abs(pc);
2490 pc = abs(p + pc);
2491 #else
2492 pa = p < 0 ? -p : p;
2493 pb = pc < 0 ? -pc : pc;
2494 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
2495 #endif
2496 p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
2497 #else /* PNG_SLOW_PAETH */
2498 p = a + b - c;
2499 pa = abs(p - a);
2500 pb = abs(p - b);
2501 pc = abs(p - c);
2502 if (pa <= pb && pa <= pc)
2503 p = a;
2504 else if (pb <= pc)
2505 p = b;
2506 else
2507 p = c;
2508 #endif /* PNG_SLOW_PAETH */
2510 v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
2512 sum += (v < 128) ? v : 256 - v;
2514 if (sum > lmins) /* We are already worse, don't continue. */
2515 break;
2516 }
2518 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2519 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2520 {
2521 int j;
2522 png_uint_32 sumhi, sumlo;
2523 sumlo = sum & PNG_LOMASK;
2524 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2526 for (j = 0; j < num_p_filters; j++)
2527 {
2528 if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
2529 {
2530 sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2531 PNG_WEIGHT_SHIFT;
2532 sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2533 PNG_WEIGHT_SHIFT;
2534 }
2535 }
2537 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2538 PNG_COST_SHIFT;
2539 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2540 PNG_COST_SHIFT;
2542 if (sumhi > PNG_HIMASK)
2543 sum = PNG_MAXSUM;
2544 else
2545 sum = (sumhi << PNG_HISHIFT) + sumlo;
2546 }
2547 #endif
2549 if (sum < mins)
2550 {
2551 best_row = png_ptr->paeth_row;
2552 }
2553 }
2555 /* Do the actual writing of the filtered row data from the chosen filter. */
2557 png_write_filtered_row(png_ptr, best_row);
2559 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2560 /* Save the type of filter we picked this time for future calculations */
2561 if (png_ptr->num_prev_filters > 0)
2562 {
2563 int j;
2564 for (j = 1; j < num_p_filters; j++)
2565 {
2566 png_ptr->prev_filters[j] = png_ptr->prev_filters[j - 1];
2567 }
2568 png_ptr->prev_filters[j] = best_row[0];
2569 }
2570 #endif
2571 }
2574 /* Do the actual writing of a previously filtered row. */
2575 void /* PRIVATE */
2576 png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row)
2577 {
2578 png_debug(1, "in png_write_filtered_row\n");
2579 png_debug1(2, "filter = %d\n", filtered_row[0]);
2580 /* set up the zlib input buffer */
2582 png_ptr->zstream.next_in = filtered_row;
2583 png_ptr->zstream.avail_in = (uInt)png_ptr->row_info.rowbytes + 1;
2584 /* repeat until we have compressed all the data */
2585 do
2586 {
2587 int ret; /* return of zlib */
2589 /* compress the data */
2590 ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
2591 /* check for compression errors */
2592 if (ret != Z_OK)
2593 {
2594 if (png_ptr->zstream.msg != NULL)
2595 png_error(png_ptr, png_ptr->zstream.msg);
2596 else
2597 png_error(png_ptr, "zlib error");
2598 }
2600 /* see if it is time to write another IDAT */
2601 if (!(png_ptr->zstream.avail_out))
2602 {
2603 /* write the IDAT and reset the zlib output buffer */
2604 png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
2605 png_ptr->zstream.next_out = png_ptr->zbuf;
2606 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
2607 }
2608 /* repeat until all data has been compressed */
2609 } while (png_ptr->zstream.avail_in);
2611 /* swap the current and previous rows */
2612 if (png_ptr->prev_row != NULL)
2613 {
2614 png_bytep tptr;
2616 tptr = png_ptr->prev_row;
2617 png_ptr->prev_row = png_ptr->row_buf;
2618 png_ptr->row_buf = tptr;
2619 }
2621 /* finish row - updates counters and flushes zlib if last row */
2622 png_write_finish_row(png_ptr);
2624 #if defined(PNG_WRITE_FLUSH_SUPPORTED)
2625 png_ptr->flush_rows++;
2627 if (png_ptr->flush_dist > 0 &&
2628 png_ptr->flush_rows >= png_ptr->flush_dist)
2629 {
2630 png_write_flush(png_ptr);
2631 }
2632 #endif
2633 }