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1
2 /* pngwutil.c - utilities to write a PNG file
3 *
4 * libpng 1.0.1
5 * For conditions of distribution and use, see copyright notice in png.h
6 * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
7 * Copyright (c) 1996, 1997 Andreas Dilger
8 * Copyright (c) 1998, Glenn Randers-Pehrson
9 * March 15, 1998
10 */
11
12 #define PNG_INTERNAL
13 #include "../png/png.h"
14
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
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 }
27
28 #if defined(PNG_WRITE_pCAL_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
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
42
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
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 }
53
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
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 }
71
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
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 (%d bytes)\n", chunk_name, length);
82
83 /* write the length */
84 png_save_uint_32(buf, length);
85 png_write_data(png_ptr, buf, (png_size_t)4);
86
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 }
93
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
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 }
109
110 /* Finish a chunk started with png_write_chunk_start(). */
111 void
112 png_write_chunk_end(png_structp png_ptr)
113 {
114 png_byte buf[4];
115
116 /* write the crc */
117 png_save_uint_32(buf, png_ptr->crc);
118
119 png_write_data(png_ptr, buf, (png_size_t)4);
120 }
121
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
129 png_write_sig(png_structp png_ptr)
130 {
131 /* write the rest of the 8 byte signature */
132 png_write_data(png_ptr, &png_sig[png_ptr->sig_bytes],
133 (png_size_t)8 - png_ptr->sig_bytes);
134 }
135
136 /* Write the IHDR chunk, and update the png_struct with the necessary
137 * information. Note that the rest of this code depends upon this
138 * information being correct.
139 */
140 void
141 png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
142 int bit_depth, int color_type, int compression_type, int filter_type,
143 int interlace_type)
144 {
145 png_byte buf[13]; /* buffer to store the IHDR info */
146
147 png_debug(1, "in png_write_IHDR\n");
148 /* Check that we have valid input data from the application info */
149 switch (color_type)
150 {
151 case PNG_COLOR_TYPE_GRAY:
152 switch (bit_depth)
153 {
154 case 1:
155 case 2:
156 case 4:
157 case 8:
158 case 16: png_ptr->channels = 1; break;
159 default: png_error(png_ptr,"Invalid bit depth for grayscale image");
160 }
161 break;
162 case PNG_COLOR_TYPE_RGB:
163 if (bit_depth != 8 && bit_depth != 16)
164 png_error(png_ptr, "Invalid bit depth for RGB image");
165 png_ptr->channels = 3;
166 break;
167 case PNG_COLOR_TYPE_PALETTE:
168 switch (bit_depth)
169 {
170 case 1:
171 case 2:
172 case 4:
173 case 8: png_ptr->channels = 1; break;
174 default: png_error(png_ptr, "Invalid bit depth for paletted image");
175 }
176 break;
177 case PNG_COLOR_TYPE_GRAY_ALPHA:
178 if (bit_depth != 8 && bit_depth != 16)
179 png_error(png_ptr, "Invalid bit depth for grayscale+alpha image");
180 png_ptr->channels = 2;
181 break;
182 case PNG_COLOR_TYPE_RGB_ALPHA:
183 if (bit_depth != 8 && bit_depth != 16)
184 png_error(png_ptr, "Invalid bit depth for RGBA image");
185 png_ptr->channels = 4;
186 break;
187 default:
188 png_error(png_ptr, "Invalid image color type specified");
189 }
190
191 if (compression_type != PNG_COMPRESSION_TYPE_BASE)
192 {
193 png_warning(png_ptr, "Invalid compression type specified");
194 compression_type = PNG_COMPRESSION_TYPE_BASE;
195 }
196
197 if (filter_type != PNG_FILTER_TYPE_BASE)
198 {
199 png_warning(png_ptr, "Invalid filter type specified");
200 filter_type = PNG_FILTER_TYPE_BASE;
201 }
202
203 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
204 if (interlace_type != PNG_INTERLACE_NONE &&
205 interlace_type != PNG_INTERLACE_ADAM7)
206 {
207 png_warning(png_ptr, "Invalid interlace type specified");
208 interlace_type = PNG_INTERLACE_ADAM7;
209 }
210 #else
211 interlace_type=PNG_INTERLACE_NONE;
212 #endif
213
214 /* save off the relevent information */
215 png_ptr->bit_depth = (png_byte)bit_depth;
216 png_ptr->color_type = (png_byte)color_type;
217 png_ptr->interlaced = (png_byte)interlace_type;
218 png_ptr->width = width;
219 png_ptr->height = height;
220
221 png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels);
222 png_ptr->rowbytes = ((width * (png_size_t)png_ptr->pixel_depth + 7) >> 3);
223 /* set the usr info, so any transformations can modify it */
224 png_ptr->usr_width = png_ptr->width;
225 png_ptr->usr_bit_depth = png_ptr->bit_depth;
226 png_ptr->usr_channels = png_ptr->channels;
227
228 /* pack the header information into the buffer */
229 png_save_uint_32(buf, width);
230 png_save_uint_32(buf + 4, height);
231 buf[8] = (png_byte)bit_depth;
232 buf[9] = (png_byte)color_type;
233 buf[10] = (png_byte)compression_type;
234 buf[11] = (png_byte)filter_type;
235 buf[12] = (png_byte)interlace_type;
236
237 /* write the chunk */
238 png_write_chunk(png_ptr, png_IHDR, buf, (png_size_t)13);
239
240 /* initialize zlib with PNG info */
241 png_ptr->zstream.zalloc = png_zalloc;
242 png_ptr->zstream.zfree = png_zfree;
243 png_ptr->zstream.opaque = (voidpf)png_ptr;
244 if (!(png_ptr->do_filter))
245 {
246 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
247 png_ptr->bit_depth < 8)
248 png_ptr->do_filter = PNG_FILTER_NONE;
249 else
250 png_ptr->do_filter = PNG_ALL_FILTERS;
251 }
252 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY))
253 {
254 if (png_ptr->do_filter != PNG_FILTER_NONE)
255 png_ptr->zlib_strategy = Z_FILTERED;
256 else
257 png_ptr->zlib_strategy = Z_DEFAULT_STRATEGY;
258 }
259 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_LEVEL))
260 png_ptr->zlib_level = Z_DEFAULT_COMPRESSION;
261 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL))
262 png_ptr->zlib_mem_level = 8;
263 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS))
264 png_ptr->zlib_window_bits = 15;
265 if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_METHOD))
266 png_ptr->zlib_method = 8;
267 deflateInit2(&png_ptr->zstream, png_ptr->zlib_level,
268 png_ptr->zlib_method, png_ptr->zlib_window_bits,
269 png_ptr->zlib_mem_level, png_ptr->zlib_strategy);
270 png_ptr->zstream.next_out = png_ptr->zbuf;
271 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
272
273 png_ptr->mode = PNG_HAVE_IHDR;
274 }
275
276 /* write the palette. We are careful not to trust png_color to be in the
277 * correct order for PNG, so people can redefine it to any convient
278 * structure.
279 */
280 void
281 png_write_PLTE(png_structp png_ptr, png_colorp palette, png_uint_32 num_pal)
282 {
283 png_uint_32 i;
284 png_colorp pal_ptr;
285 png_byte buf[3];
286
287 png_debug(1, "in png_write_PLTE\n");
288 if (num_pal == 0 || num_pal > 256)
289 {
290 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
291 {
292 png_error(png_ptr, "Invalid number of colors in palette");
293 }
294 else
295 {
296 png_warning(png_ptr, "Invalid number of colors in palette");
297 return;
298 }
299 }
300
301 png_ptr->num_palette = (png_uint_16)num_pal;
302 png_debug1(3, "num_palette = %d\n", png_ptr->num_palette);
303
304 png_write_chunk_start(png_ptr, png_PLTE, num_pal * 3);
305 for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++)
306 {
307 buf[0] = pal_ptr->red;
308 buf[1] = pal_ptr->green;
309 buf[2] = pal_ptr->blue;
310 png_write_chunk_data(png_ptr, buf, (png_size_t)3);
311 }
312 png_write_chunk_end(png_ptr);
313 png_ptr->mode |= PNG_HAVE_PLTE;
314 }
315
316 /* write an IDAT chunk */
317 void
318 png_write_IDAT(png_structp png_ptr, png_bytep data, png_size_t length)
319 {
320 png_debug(1, "in png_write_IDAT\n");
321 png_write_chunk(png_ptr, png_IDAT, data, length);
322 png_ptr->mode |= PNG_HAVE_IDAT;
323 }
324
325 /* write an IEND chunk */
326 void
327 png_write_IEND(png_structp png_ptr)
328 {
329 png_debug(1, "in png_write_IEND\n");
330 png_write_chunk(png_ptr, png_IEND, NULL, (png_size_t)0);
331 png_ptr->mode |= PNG_HAVE_IEND;
332 }
333
334 #if defined(PNG_WRITE_gAMA_SUPPORTED)
335 /* write a gAMA chunk */
336 void
337 png_write_gAMA(png_structp png_ptr, double file_gamma)
338 {
339 png_uint_32 igamma;
340 png_byte buf[4];
341
342 png_debug(1, "in png_write_gAMA\n");
343 /* file_gamma is saved in 1/1000000ths */
344 igamma = (png_uint_32)(file_gamma * 100000.0 + 0.5);
345 png_save_uint_32(buf, igamma);
346 png_write_chunk(png_ptr, png_gAMA, buf, (png_size_t)4);
347 }
348 #endif
349
350 #if defined(PNG_WRITE_sRGB_SUPPORTED)
351 /* write a sRGB chunk */
352 void
353 png_write_sRGB(png_structp png_ptr, int srgb_intent)
354 {
355 png_byte buf[1];
356
357 png_debug(1, "in png_write_sRGB\n");
358 if(srgb_intent >= PNG_sRGB_INTENT_LAST)
359 png_warning(png_ptr,
360 "Invalid sRGB rendering intent specified");
361 buf[0]=(png_byte)srgb_intent;
362 png_write_chunk(png_ptr, png_sRGB, buf, (png_size_t)1);
363 }
364 #endif
365
366 #if defined(PNG_WRITE_sBIT_SUPPORTED)
367 /* write the sBIT chunk */
368 void
369 png_write_sBIT(png_structp png_ptr, png_color_8p sbit, int color_type)
370 {
371 png_byte buf[4];
372 png_size_t size;
373
374 png_debug(1, "in png_write_sBIT\n");
375 /* make sure we don't depend upon the order of PNG_COLOR_8 */
376 if (color_type & PNG_COLOR_MASK_COLOR)
377 {
378 png_byte maxbits;
379
380 maxbits = color_type==PNG_COLOR_TYPE_PALETTE ? 8:png_ptr->usr_bit_depth;
381 if (sbit->red == 0 || sbit->red > maxbits ||
382 sbit->green == 0 || sbit->green > maxbits ||
383 sbit->blue == 0 || sbit->blue > maxbits)
384 {
385 png_warning(png_ptr, "Invalid sBIT depth specified");
386 return;
387 }
388 buf[0] = sbit->red;
389 buf[1] = sbit->green;
390 buf[2] = sbit->blue;
391 size = 3;
392 }
393 else
394 {
395 if (sbit->gray == 0 || sbit->gray > png_ptr->usr_bit_depth)
396 {
397 png_warning(png_ptr, "Invalid sBIT depth specified");
398 return;
399 }
400 buf[0] = sbit->gray;
401 size = 1;
402 }
403
404 if (color_type & PNG_COLOR_MASK_ALPHA)
405 {
406 if (sbit->alpha == 0 || sbit->alpha > png_ptr->usr_bit_depth)
407 {
408 png_warning(png_ptr, "Invalid sBIT depth specified");
409 return;
410 }
411 buf[size++] = sbit->alpha;
412 }
413
414 png_write_chunk(png_ptr, png_sBIT, buf, size);
415 }
416 #endif
417
418 #if defined(PNG_WRITE_cHRM_SUPPORTED)
419 /* write the cHRM chunk */
420 void
421 png_write_cHRM(png_structp png_ptr, double white_x, double white_y,
422 double red_x, double red_y, double green_x, double green_y,
423 double blue_x, double blue_y)
424 {
425 png_uint_32 itemp;
426 png_byte buf[32];
427
428 png_debug(1, "in png_write_cHRM\n");
429 /* each value is saved int 1/1000000ths */
430 if (white_x < 0 || white_x > 0.8 || white_y < 0 || white_y > 0.8 ||
431 white_x + white_y > 1.0)
432 {
433 png_warning(png_ptr, "Invalid cHRM white point specified");
434 return;
435 }
436 itemp = (png_uint_32)(white_x * 100000.0 + 0.5);
437 png_save_uint_32(buf, itemp);
438 itemp = (png_uint_32)(white_y * 100000.0 + 0.5);
439 png_save_uint_32(buf + 4, itemp);
440
441 if (red_x < 0 || red_x > 0.8 || red_y < 0 || red_y > 0.8 ||
442 red_x + red_y > 1.0)
443 {
444 png_warning(png_ptr, "Invalid cHRM red point specified");
445 return;
446 }
447 itemp = (png_uint_32)(red_x * 100000.0 + 0.5);
448 png_save_uint_32(buf + 8, itemp);
449 itemp = (png_uint_32)(red_y * 100000.0 + 0.5);
450 png_save_uint_32(buf + 12, itemp);
451
452 if (green_x < 0 || green_x > 0.8 || green_y < 0 || green_y > 0.8 ||
453 green_x + green_y > 1.0)
454 {
455 png_warning(png_ptr, "Invalid cHRM green point specified");
456 return;
457 }
458 itemp = (png_uint_32)(green_x * 100000.0 + 0.5);
459 png_save_uint_32(buf + 16, itemp);
460 itemp = (png_uint_32)(green_y * 100000.0 + 0.5);
461 png_save_uint_32(buf + 20, itemp);
462
463 if (blue_x < 0 || blue_x > 0.8 || blue_y < 0 || blue_y > 0.8 ||
464 blue_x + blue_y > 1.0)
465 {
466 png_warning(png_ptr, "Invalid cHRM blue point specified");
467 return;
468 }
469 itemp = (png_uint_32)(blue_x * 100000.0 + 0.5);
470 png_save_uint_32(buf + 24, itemp);
471 itemp = (png_uint_32)(blue_y * 100000.0 + 0.5);
472 png_save_uint_32(buf + 28, itemp);
473
474 png_write_chunk(png_ptr, png_cHRM, buf, (png_size_t)32);
475 }
476 #endif
477
478 #if defined(PNG_WRITE_tRNS_SUPPORTED)
479 /* write the tRNS chunk */
480 void
481 png_write_tRNS(png_structp png_ptr, png_bytep trans, png_color_16p tran,
482 int num_trans, int color_type)
483 {
484 png_byte buf[6];
485
486 png_debug(1, "in png_write_tRNS\n");
487 if (color_type == PNG_COLOR_TYPE_PALETTE)
488 {
489 if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette)
490 {
491 png_warning(png_ptr,"Invalid number of transparent colors specified");
492 return;
493 }
494 /* write the chunk out as it is */
495 png_write_chunk(png_ptr, png_tRNS, trans, (png_size_t)num_trans);
496 }
497 else if (color_type == PNG_COLOR_TYPE_GRAY)
498 {
499 /* one 16 bit value */
500 png_save_uint_16(buf, tran->gray);
501 png_write_chunk(png_ptr, png_tRNS, buf, (png_size_t)2);
502 }
503 else if (color_type == PNG_COLOR_TYPE_RGB)
504 {
505 /* three 16 bit values */
506 png_save_uint_16(buf, tran->red);
507 png_save_uint_16(buf + 2, tran->green);
508 png_save_uint_16(buf + 4, tran->blue);
509 png_write_chunk(png_ptr, png_tRNS, buf, (png_size_t)6);
510 }
511 else
512 {
513 png_warning(png_ptr, "Can't write tRNS with an alpha channel");
514 }
515 }
516 #endif
517
518 #if defined(PNG_WRITE_bKGD_SUPPORTED)
519 /* write the background chunk */
520 void
521 png_write_bKGD(png_structp png_ptr, png_color_16p back, int color_type)
522 {
523 png_byte buf[6];
524
525 png_debug(1, "in png_write_bKGD\n");
526 if (color_type == PNG_COLOR_TYPE_PALETTE)
527 {
528 if (back->index > png_ptr->num_palette)
529 {
530 png_warning(png_ptr, "Invalid background palette index");
531 return;
532 }
533 buf[0] = back->index;
534 png_write_chunk(png_ptr, png_bKGD, buf, (png_size_t)1);
535 }
536 else if (color_type & PNG_COLOR_MASK_COLOR)
537 {
538 png_save_uint_16(buf, back->red);
539 png_save_uint_16(buf + 2, back->green);
540 png_save_uint_16(buf + 4, back->blue);
541 png_write_chunk(png_ptr, png_bKGD, buf, (png_size_t)6);
542 }
543 else
544 {
545 png_save_uint_16(buf, back->gray);
546 png_write_chunk(png_ptr, png_bKGD, buf, (png_size_t)2);
547 }
548 }
549 #endif
550
551 #if defined(PNG_WRITE_hIST_SUPPORTED)
552 /* write the histogram */
553 void
554 png_write_hIST(png_structp png_ptr, png_uint_16p hist, int num_hist)
555 {
556 int i;
557 png_byte buf[3];
558
559 png_debug(1, "in png_write_hIST\n");
560 if (num_hist > (int)png_ptr->num_palette)
561 {
562 png_debug2(3, "num_hist = %d, num_palette = %d\n", num_hist,
563 png_ptr->num_palette);
564 png_warning(png_ptr, "Invalid number of histogram entries specified");
565 return;
566 }
567
568 png_write_chunk_start(png_ptr, png_hIST, (png_uint_32)(num_hist * 2));
569 for (i = 0; i < num_hist; i++)
570 {
571 png_save_uint_16(buf, hist[i]);
572 png_write_chunk_data(png_ptr, buf, (png_size_t)2);
573 }
574 png_write_chunk_end(png_ptr);
575 }
576 #endif
577
578 #if defined(PNG_WRITE_tEXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED)
579 /* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification,
580 * and if invalid, correct the keyword rather than discarding the entire
581 * chunk. The PNG 1.0 specification requires keywords 1-79 characters in
582 * length, forbids leading or trailing whitespace, multiple internal spaces,
583 * and the non-break space (0x80) from ISO 8859-1. Returns keyword length.
584 *
585 * The new_key is allocated to hold the corrected keyword and must be freed
586 * by the calling routine. This avoids problems with trying to write to
587 * static keywords without having to have duplicate copies of the strings.
588 */
589 png_size_t
590 png_check_keyword(png_structp png_ptr, png_charp key, png_charpp new_key)
591 {
592 png_size_t key_len;
593 png_charp kp, dp;
594 int kflag;
595
596 png_debug(1, "in png_check_keyword\n");
597 *new_key = NULL;
598
599 if (key == NULL || (key_len = png_strlen(key)) == 0)
600 {
601 png_chunk_warning(png_ptr, "zero length keyword");
602 return ((png_size_t)0);
603 }
604
605 png_debug1(2, "Keyword to be checked is '%s'\n", key);
606
607 *new_key = (png_charp)png_malloc(png_ptr, (png_uint_32)(key_len + 1));
608
609 /* Replace non-printing characters with a blank and print a warning */
610 for (kp = key, dp = *new_key; *kp != '\0'; kp++, dp++)
611 {
612 if (*kp < 0x20 || (*kp > 0x7E && (png_byte)*kp < 0xA1))
613 {
614 #if !defined(PNG_NO_STDIO)
615 char msg[40];
616
617 sprintf(msg, "invalid keyword character 0x%02X", *kp);
618 png_chunk_warning(png_ptr, msg);
619 #else
620 png_chunk_warning(png_ptr, "invalid character in keyword");
621 #endif
622 *dp = ' ';
623 }
624 else
625 {
626 *dp = *kp;
627 }
628 }
629 *dp = '\0';
630
631 /* Remove any trailing white space. */
632 kp = *new_key + key_len - 1;
633 if (*kp == ' ')
634 {
635 png_chunk_warning(png_ptr, "trailing spaces removed from keyword");
636
637 while (*kp == ' ')
638 {
639 *(kp--) = '\0';
640 key_len--;
641 }
642 }
643
644 /* Remove any leading white space. */
645 kp = *new_key;
646 if (*kp == ' ')
647 {
648 png_chunk_warning(png_ptr, "leading spaces removed from keyword");
649
650 while (*kp == ' ')
651 {
652 kp++;
653 key_len--;
654 }
655 }
656
657 png_debug1(2, "Checking for multiple internal spaces in '%s'\n", kp);
658
659 /* Remove multiple internal spaces. */
660 for (kflag = 0, dp = *new_key; *kp != '\0'; kp++)
661 {
662 if (*kp == ' ' && kflag == 0)
663 {
664 *(dp++) = *kp;
665 kflag = 1;
666 }
667 else if (*kp == ' ')
668 {
669 key_len--;
670 }
671 else
672 {
673 *(dp++) = *kp;
674 kflag = 0;
675 }
676 }
677 *dp = '\0';
678
679 if (key_len == 0)
680 {
681 png_chunk_warning(png_ptr, "zero length keyword");
682 }
683
684 if (key_len > 79)
685 {
686 png_chunk_warning(png_ptr, "keyword length must be 1 - 79 characters");
687 new_key[79] = '\0';
688 key_len = 79;
689 }
690
691 return (key_len);
692 }
693 #endif
694
695 #if defined(PNG_WRITE_tEXt_SUPPORTED)
696 /* write a tEXt chunk */
697 void
698 png_write_tEXt(png_structp png_ptr, png_charp key, png_charp text,
699 png_size_t text_len)
700 {
701 png_size_t key_len;
702 png_charp new_key;
703
704 png_debug(1, "in png_write_tEXt\n");
705 if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0)
706 {
707 png_warning(png_ptr, "Empty keyword in tEXt chunk");
708 return;
709 }
710
711 if (text == NULL || *text == '\0')
712 text_len = 0;
713
714 /* make sure we include the 0 after the key */
715 png_write_chunk_start(png_ptr, png_tEXt, (png_uint_32)key_len+text_len+1);
716 png_write_chunk_data(png_ptr, (png_bytep)new_key, key_len + 1);
717 if (text_len)
718 png_write_chunk_data(png_ptr, (png_bytep)text, text_len);
719
720 png_write_chunk_end(png_ptr);
721 png_free(png_ptr, new_key);
722 }
723 #endif
724
725 #if defined(PNG_WRITE_zTXt_SUPPORTED)
726 /* write a compressed text chunk */
727 void
728 png_write_zTXt(png_structp png_ptr, png_charp key, png_charp text,
729 png_size_t text_len, int compression)
730 {
731 png_size_t key_len;
732 char buf[1];
733 png_charp new_key;
734 int i, ret;
735 png_charpp output_ptr = NULL; /* array of pointers to output */
736 int num_output_ptr = 0; /* number of output pointers used */
737 int max_output_ptr = 0; /* size of output_ptr */
738
739 png_debug(1, "in png_write_zTXt\n");
740
741 if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0)
742 {
743 png_warning(png_ptr, "Empty keyword in zTXt chunk");
744 return;
745 }
746
747 if (text == NULL || *text == '\0' || compression==PNG_TEXT_COMPRESSION_NONE)
748 {
749 png_write_tEXt(png_ptr, new_key, text, (png_size_t)0);
750 png_free(png_ptr, new_key);
751 return;
752 }
753
754 png_free(png_ptr, new_key);
755
756 if (compression >= PNG_TEXT_COMPRESSION_LAST)
757 {
758 #if !defined(PNG_NO_STDIO)
759 char msg[50];
760 sprintf(msg, "Unknown zTXt compression type %d", compression);
761 png_warning(png_ptr, msg);
762 #else
763 png_warning(png_ptr, "Unknown zTXt compression type");
764 #endif
765 compression = PNG_TEXT_COMPRESSION_zTXt;
766 }
767
768 /* We can't write the chunk until we find out how much data we have,
769 * which means we need to run the compressor first, and save the
770 * output. This shouldn't be a problem, as the vast majority of
771 * comments should be reasonable, but we will set up an array of
772 * malloc'd pointers to be sure.
773 *
774 * If we knew the application was well behaved, we could simplify this
775 * greatly by assuming we can always malloc an output buffer large
776 * enough to hold the compressed text ((1001 * text_len / 1000) + 12)
777 * and malloc this directly. The only time this would be a bad idea is
778 * if we can't malloc more than 64K and we have 64K of random input
779 * data, or if the input string is incredibly large (although this
780 * wouldn't cause a failure, just a slowdown due to swapping).
781 */
782
783 /* set up the compression buffers */
784 png_ptr->zstream.avail_in = (uInt)text_len;
785 png_ptr->zstream.next_in = (Bytef *)text;
786 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
787 png_ptr->zstream.next_out = (Bytef *)png_ptr->zbuf;
788
789 /* this is the same compression loop as in png_write_row() */
790 do
791 {
792 /* compress the data */
793 ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
794 if (ret != Z_OK)
795 {
796 /* error */
797 if (png_ptr->zstream.msg != NULL)
798 png_error(png_ptr, png_ptr->zstream.msg);
799 else
800 png_error(png_ptr, "zlib error");
801 }
802 /* check to see if we need more room */
803 if (!png_ptr->zstream.avail_out && png_ptr->zstream.avail_in)
804 {
805 /* make sure the output array has room */
806 if (num_output_ptr >= max_output_ptr)
807 {
808 int old_max;
809
810 old_max = max_output_ptr;
811 max_output_ptr = num_output_ptr + 4;
812 if (output_ptr != NULL)
813 {
814 png_charpp old_ptr;
815
816 old_ptr = output_ptr;
817 output_ptr = (png_charpp)png_malloc(png_ptr,
818 (png_uint_32)(max_output_ptr * sizeof (png_charpp)));
819 png_memcpy(output_ptr, old_ptr, old_max * sizeof (png_charp));
820 png_free(png_ptr, old_ptr);
821 }
822 else
823 output_ptr = (png_charpp)png_malloc(png_ptr,
824 (png_uint_32)(max_output_ptr * sizeof (png_charp)));
825 }
826
827 /* save the data */
828 output_ptr[num_output_ptr] = (png_charp)png_malloc(png_ptr,
829 (png_uint_32)png_ptr->zbuf_size);
830 png_memcpy(output_ptr[num_output_ptr], png_ptr->zbuf,
831 png_ptr->zbuf_size);
832 num_output_ptr++;
833
834 /* and reset the buffer */
835 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
836 png_ptr->zstream.next_out = png_ptr->zbuf;
837 }
838 /* continue until we don't have anymore to compress */
839 } while (png_ptr->zstream.avail_in);
840
841 /* finish the compression */
842 do
843 {
844 /* tell zlib we are finished */
845 ret = deflate(&png_ptr->zstream, Z_FINISH);
846 if (ret != Z_OK && ret != Z_STREAM_END)
847 {
848 /* we got an error */
849 if (png_ptr->zstream.msg != NULL)
850 png_error(png_ptr, png_ptr->zstream.msg);
851 else
852 png_error(png_ptr, "zlib error");
853 }
854
855 /* check to see if we need more room */
856 if (!(png_ptr->zstream.avail_out) && ret == Z_OK)
857 {
858 /* check to make sure our output array has room */
859 if (num_output_ptr >= max_output_ptr)
860 {
861 int old_max;
862
863 old_max = max_output_ptr;
864 max_output_ptr = num_output_ptr + 4;
865 if (output_ptr != NULL)
866 {
867 png_charpp old_ptr;
868
869 old_ptr = output_ptr;
870 /* This could be optimized to realloc() */
871 output_ptr = (png_charpp)png_malloc(png_ptr,
872 (png_uint_32)(max_output_ptr * sizeof (png_charpp)));
873 png_memcpy(output_ptr, old_ptr, old_max * sizeof (png_charp));
874 png_free(png_ptr, old_ptr);
875 }
876 else
877 output_ptr = (png_charpp)png_malloc(png_ptr,
878 (png_uint_32)(max_output_ptr * sizeof (png_charp)));
879 }
880
881 /* save off the data */
882 output_ptr[num_output_ptr] = (png_charp)png_malloc(png_ptr,
883 (png_uint_32)png_ptr->zbuf_size);
884 png_memcpy(output_ptr[num_output_ptr], png_ptr->zbuf,
885 png_ptr->zbuf_size);
886 num_output_ptr++;
887
888 /* and reset the buffer pointers */
889 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
890 png_ptr->zstream.next_out = png_ptr->zbuf;
891 }
892 } while (ret != Z_STREAM_END);
893
894 /* text length is number of buffers plus last buffer */
895 text_len = png_ptr->zbuf_size * num_output_ptr;
896 if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
897 text_len += png_ptr->zbuf_size - (png_size_t)png_ptr->zstream.avail_out;
898
899 /* write start of chunk */
900 png_write_chunk_start(png_ptr, png_zTXt, (png_uint_32)(key_len+text_len+2));
901 /* write key */
902 png_write_chunk_data(png_ptr, (png_bytep)key, key_len + 1);
903 buf[0] = (png_byte)compression;
904 /* write compression */
905 png_write_chunk_data(png_ptr, (png_bytep)buf, (png_size_t)1);
906
907 /* write saved output buffers, if any */
908 for (i = 0; i < num_output_ptr; i++)
909 {
910 png_write_chunk_data(png_ptr,(png_bytep)output_ptr[i],png_ptr->zbuf_size);
911 png_free(png_ptr, output_ptr[i]);
912 }
913 if (max_output_ptr != 0)
914 png_free(png_ptr, output_ptr);
915 /* write anything left in zbuf */
916 if (png_ptr->zstream.avail_out < (png_uint_32)png_ptr->zbuf_size)
917 png_write_chunk_data(png_ptr, png_ptr->zbuf,
918 png_ptr->zbuf_size - png_ptr->zstream.avail_out);
919 /* close the chunk */
920 png_write_chunk_end(png_ptr);
921
922 /* reset zlib for another zTXt or the image data */
923 deflateReset(&png_ptr->zstream);
924 }
925 #endif
926
927
928 #if defined(PNG_WRITE_oFFs_SUPPORTED)
929 /* write the oFFs chunk */
930 void
931 png_write_oFFs(png_structp png_ptr, png_uint_32 x_offset,
932 png_uint_32 y_offset,
933 int unit_type)
934 {
935 png_byte buf[9];
936
937 png_debug(1, "in png_write_oFFs\n");
938 if (unit_type >= PNG_OFFSET_LAST)
939 png_warning(png_ptr, "Unrecognized unit type for oFFs chunk");
940
941 png_save_uint_32(buf, x_offset);
942 png_save_uint_32(buf + 4, y_offset);
943 buf[8] = (png_byte)unit_type;
944
945 png_write_chunk(png_ptr, png_oFFs, buf, (png_size_t)9);
946 }
947 #endif
948
949 #if defined(PNG_WRITE_pCAL_SUPPORTED)
950 /* write the pCAL chunk (png-scivis-19970203) */
951 void
952 png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
953 png_int_32 X1, int type, int nparams, png_charp units, png_charpp params)
954 {
955 png_size_t purpose_len, units_len, total_len;
956 png_uint_32p params_len;
957 png_byte buf[10];
958 png_charp new_purpose;
959 int i;
960
961 png_debug1(1, "in png_write_pCAL (%d parameters)\n", nparams);
962 if (type >= PNG_EQUATION_LAST)
963 png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");
964
965 purpose_len = png_check_keyword(png_ptr, purpose, &new_purpose) + 1;
966 png_debug1(3, "pCAL purpose length = %d\n", purpose_len);
967 units_len = png_strlen(units) + (nparams == 0 ? 0 : 1);
968 png_debug1(3, "pCAL units length = %d\n", units_len);
969 total_len = purpose_len + units_len + 10;
970
971 params_len = (png_uint_32p)png_malloc(png_ptr, (png_uint_32)(nparams
972 *sizeof(png_uint_32)));
973
974 /* Find the length of each parameter, making sure we don't count the
975 null terminator for the last parameter. */
976 for (i = 0; i < nparams; i++)
977 {
978 params_len[i] = png_strlen(params[i]) + (i == nparams - 1 ? 0 : 1);
979 png_debug2(3, "pCAL parameter %d length = %d\n", i, params_len[i]);
980 total_len += (png_size_t)params_len[i];
981 }
982
983 png_debug1(3, "pCAL total length = %d\n", total_len);
984 png_write_chunk_start(png_ptr, png_pCAL, (png_uint_32)total_len);
985 png_write_chunk_data(png_ptr, (png_bytep)new_purpose, purpose_len);
986 png_save_int_32(buf, X0);
987 png_save_int_32(buf + 4, X1);
988 buf[8] = (png_byte)type;
989 buf[9] = (png_byte)nparams;
990 png_write_chunk_data(png_ptr, buf, (png_size_t)10);
991 png_write_chunk_data(png_ptr, (png_bytep)units, (png_size_t)units_len);
992
993 png_free(png_ptr, new_purpose);
994
995 for (i = 0; i < nparams; i++)
996 {
997 png_write_chunk_data(png_ptr, (png_bytep)params[i],
998 (png_size_t)params_len[i]);
999 }
1000
1001 png_free(png_ptr, params_len);
1002 png_write_chunk_end(png_ptr);
1003 }
1004 #endif
1005
1006 #if defined(PNG_WRITE_pHYs_SUPPORTED)
1007 /* write the pHYs chunk */
1008 void
1009 png_write_pHYs(png_structp png_ptr, png_uint_32 x_pixels_per_unit,
1010 png_uint_32 y_pixels_per_unit,
1011 int unit_type)
1012 {
1013 png_byte buf[9];
1014
1015 png_debug(1, "in png_write_pHYs\n");
1016 if (unit_type >= PNG_RESOLUTION_LAST)
1017 png_warning(png_ptr, "Unrecognized unit type for pHYs chunk");
1018
1019 png_save_uint_32(buf, x_pixels_per_unit);
1020 png_save_uint_32(buf + 4, y_pixels_per_unit);
1021 buf[8] = (png_byte)unit_type;
1022
1023 png_write_chunk(png_ptr, png_pHYs, buf, (png_size_t)9);
1024 }
1025 #endif
1026
1027 #if defined(PNG_WRITE_tIME_SUPPORTED)
1028 /* Write the tIME chunk. Use either png_convert_from_struct_tm()
1029 * or png_convert_from_time_t(), or fill in the structure yourself.
1030 */
1031 void
1032 png_write_tIME(png_structp png_ptr, png_timep mod_time)
1033 {
1034 png_byte buf[7];
1035
1036 png_debug(1, "in png_write_tIME\n");
1037 if (mod_time->month > 12 || mod_time->month < 1 ||
1038 mod_time->day > 31 || mod_time->day < 1 ||
1039 mod_time->hour > 23 || mod_time->second > 60)
1040 {
1041 png_warning(png_ptr, "Invalid time specified for tIME chunk");
1042 return;
1043 }
1044
1045 png_save_uint_16(buf, mod_time->year);
1046 buf[2] = mod_time->month;
1047 buf[3] = mod_time->day;
1048 buf[4] = mod_time->hour;
1049 buf[5] = mod_time->minute;
1050 buf[6] = mod_time->second;
1051
1052 png_write_chunk(png_ptr, png_tIME, buf, (png_size_t)7);
1053 }
1054 #endif
1055
1056 /* initializes the row writing capability of libpng */
1057 void
1058 png_write_start_row(png_structp png_ptr)
1059 {
1060 png_size_t buf_size;
1061
1062 png_debug(1, "in png_write_start_row\n");
1063 buf_size = (png_size_t)(((png_ptr->width * png_ptr->usr_channels *
1064 png_ptr->usr_bit_depth + 7) >> 3) + 1);
1065
1066 /* set up row buffer */
1067 png_ptr->row_buf = (png_bytep)png_malloc(png_ptr, (png_uint_32)buf_size);
1068 png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE;
1069
1070 /* set up filtering buffer, if using this filter */
1071 if (png_ptr->do_filter & PNG_FILTER_SUB)
1072 {
1073 png_ptr->sub_row = (png_bytep)png_malloc(png_ptr,
1074 (png_ptr->rowbytes + 1));
1075 png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
1076 }
1077
1078 /* We only need to keep the previous row if we are using one of these. */
1079 if (png_ptr->do_filter & (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH))
1080 {
1081 /* set up previous row buffer */
1082 png_ptr->prev_row = (png_bytep)png_malloc(png_ptr, (png_uint_32)buf_size);
1083 png_memset(png_ptr->prev_row, 0, buf_size);
1084
1085 if (png_ptr->do_filter & PNG_FILTER_UP)
1086 {
1087 png_ptr->up_row = (png_bytep )png_malloc(png_ptr,
1088 (png_ptr->rowbytes + 1));
1089 png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;
1090 }
1091
1092 if (png_ptr->do_filter & PNG_FILTER_AVG)
1093 {
1094 png_ptr->avg_row = (png_bytep)png_malloc(png_ptr,
1095 (png_ptr->rowbytes + 1));
1096 png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;
1097 }
1098
1099 if (png_ptr->do_filter & PNG_FILTER_PAETH)
1100 {
1101 png_ptr->paeth_row = (png_bytep )png_malloc(png_ptr,
1102 (png_ptr->rowbytes + 1));
1103 png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
1104 }
1105 }
1106
1107 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
1108 /* if interlaced, we need to set up width and height of pass */
1109 if (png_ptr->interlaced)
1110 {
1111 if (!(png_ptr->transformations & PNG_INTERLACE))
1112 {
1113 png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
1114 png_pass_ystart[0]) / png_pass_yinc[0];
1115 png_ptr->usr_width = (png_ptr->width + png_pass_inc[0] - 1 -
1116 png_pass_start[0]) / png_pass_inc[0];
1117 }
1118 else
1119 {
1120 png_ptr->num_rows = png_ptr->height;
1121 png_ptr->usr_width = png_ptr->width;
1122 }
1123 }
1124 else
1125 #endif
1126 {
1127 png_ptr->num_rows = png_ptr->height;
1128 png_ptr->usr_width = png_ptr->width;
1129 }
1130 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1131 png_ptr->zstream.next_out = png_ptr->zbuf;
1132 }
1133
1134 /* Internal use only. Called when finished processing a row of data. */
1135 void
1136 png_write_finish_row(png_structp png_ptr)
1137 {
1138 int ret;
1139
1140 png_debug(1, "in png_write_finish_row\n");
1141 /* next row */
1142 png_ptr->row_number++;
1143
1144 /* see if we are done */
1145 if (png_ptr->row_number < png_ptr->num_rows)
1146 return;
1147
1148 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
1149 /* if interlaced, go to next pass */
1150 if (png_ptr->interlaced)
1151 {
1152 png_ptr->row_number = 0;
1153 if (png_ptr->transformations & PNG_INTERLACE)
1154 {
1155 png_ptr->pass++;
1156 }
1157 else
1158 {
1159 /* loop until we find a non-zero width or height pass */
1160 do
1161 {
1162 png_ptr->pass++;
1163 if (png_ptr->pass >= 7)
1164 break;
1165 png_ptr->usr_width = (png_ptr->width +
1166 png_pass_inc[png_ptr->pass] - 1 -
1167 png_pass_start[png_ptr->pass]) /
1168 png_pass_inc[png_ptr->pass];
1169 png_ptr->num_rows = (png_ptr->height +
1170 png_pass_yinc[png_ptr->pass] - 1 -
1171 png_pass_ystart[png_ptr->pass]) /
1172 png_pass_yinc[png_ptr->pass];
1173 if (png_ptr->transformations & PNG_INTERLACE)
1174 break;
1175 } while (png_ptr->usr_width == 0 || png_ptr->num_rows == 0);
1176
1177 }
1178
1179 /* reset the row above the image for the next pass */
1180 if (png_ptr->pass < 7)
1181 {
1182 if (png_ptr->prev_row != NULL)
1183 png_memset(png_ptr->prev_row, 0,
1184 (png_size_t) (((png_uint_32)png_ptr->usr_channels *
1185 (png_uint_32)png_ptr->usr_bit_depth *
1186 png_ptr->width + 7) >> 3) + 1);
1187 return;
1188 }
1189 }
1190 #endif
1191
1192 /* if we get here, we've just written the last row, so we need
1193 to flush the compressor */
1194 do
1195 {
1196 /* tell the compressor we are done */
1197 ret = deflate(&png_ptr->zstream, Z_FINISH);
1198 /* check for an error */
1199 if (ret != Z_OK && ret != Z_STREAM_END)
1200 {
1201 if (png_ptr->zstream.msg != NULL)
1202 png_error(png_ptr, png_ptr->zstream.msg);
1203 else
1204 png_error(png_ptr, "zlib error");
1205 }
1206 /* check to see if we need more room */
1207 if (!(png_ptr->zstream.avail_out) && ret == Z_OK)
1208 {
1209 png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
1210 png_ptr->zstream.next_out = png_ptr->zbuf;
1211 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1212 }
1213 } while (ret != Z_STREAM_END);
1214
1215 /* write any extra space */
1216 if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
1217 {
1218 png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size -
1219 png_ptr->zstream.avail_out);
1220 }
1221
1222 deflateReset(&png_ptr->zstream);
1223 }
1224
1225 #if defined(PNG_WRITE_INTERLACING_SUPPORTED)
1226 /* Pick out the correct pixels for the interlace pass.
1227 * The basic idea here is to go through the row with a source
1228 * pointer and a destination pointer (sp and dp), and copy the
1229 * correct pixels for the pass. As the row gets compacted,
1230 * sp will always be >= dp, so we should never overwrite anything.
1231 * See the default: case for the easiest code to understand.
1232 */
1233 void
1234 png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
1235 {
1236 png_debug(1, "in png_do_write_interlace\n");
1237 /* we don't have to do anything on the last pass (6) */
1238 #if defined(PNG_USELESS_TESTS_SUPPORTED)
1239 if (row != NULL && row_info != NULL && pass < 6)
1240 #else
1241 if (pass < 6)
1242 #endif
1243 {
1244 /* each pixel depth is handled seperately */
1245 switch (row_info->pixel_depth)
1246 {
1247 case 1:
1248 {
1249 png_bytep sp;
1250 png_bytep dp;
1251 int shift;
1252 int d;
1253 int value;
1254 png_uint_32 i;
1255
1256 dp = row;
1257 d = 0;
1258 shift = 7;
1259 for (i = png_pass_start[pass]; i < row_info->width;
1260 i += png_pass_inc[pass])
1261 {
1262 sp = row + (png_size_t)(i >> 3);
1263 value = (int)(*sp >> (7 - (int)(i & 7))) & 0x1;
1264 d |= (value << shift);
1265
1266 if (shift == 0)
1267 {
1268 shift = 7;
1269 *dp++ = (png_byte)d;
1270 d = 0;
1271 }
1272 else
1273 shift--;
1274
1275 }
1276 if (shift != 7)
1277 *dp = (png_byte)d;
1278 break;
1279 }
1280 case 2:
1281 {
1282 png_bytep sp;
1283 png_bytep dp;
1284 int shift;
1285 int d;
1286 int value;
1287 png_uint_32 i;
1288
1289 dp = row;
1290 shift = 6;
1291 d = 0;
1292 for (i = png_pass_start[pass]; i < row_info->width;
1293 i += png_pass_inc[pass])
1294 {
1295 sp = row + (png_size_t)(i >> 2);
1296 value = (*sp >> ((3 - (int)(i & 3)) << 1)) & 0x3;
1297 d |= (value << shift);
1298
1299 if (shift == 0)
1300 {
1301 shift = 6;
1302 *dp++ = (png_byte)d;
1303 d = 0;
1304 }
1305 else
1306 shift -= 2;
1307 }
1308 if (shift != 6)
1309 *dp = (png_byte)d;
1310 break;
1311 }
1312 case 4:
1313 {
1314 png_bytep sp;
1315 png_bytep dp;
1316 int shift;
1317 int d;
1318 int value;
1319 png_uint_32 i;
1320
1321 dp = row;
1322 shift = 4;
1323 d = 0;
1324 for (i = png_pass_start[pass]; i < row_info->width;
1325 i += png_pass_inc[pass])
1326 {
1327 sp = row + (png_size_t)(i >> 1);
1328 value = (*sp >> ((1 - (int)(i & 1)) << 2)) & 0xf;
1329 d |= (value << shift);
1330
1331 if (shift == 0)
1332 {
1333 shift = 4;
1334 *dp++ = (png_byte)d;
1335 d = 0;
1336 }
1337 else
1338 shift -= 4;
1339 }
1340 if (shift != 4)
1341 *dp = (png_byte)d;
1342 break;
1343 }
1344 default:
1345 {
1346 png_bytep sp;
1347 png_bytep dp;
1348 png_uint_32 i;
1349 png_size_t pixel_bytes;
1350
1351 /* start at the beginning */
1352 dp = row;
1353 /* find out how many bytes each pixel takes up */
1354 pixel_bytes = (row_info->pixel_depth >> 3);
1355 /* loop through the row, only looking at the pixels that
1356 matter */
1357 for (i = png_pass_start[pass]; i < row_info->width;
1358 i += png_pass_inc[pass])
1359 {
1360 /* find out where the original pixel is */
1361 sp = row + (png_size_t)i * pixel_bytes;
1362 /* move the pixel */
1363 if (dp != sp)
1364 png_memcpy(dp, sp, pixel_bytes);
1365 /* next pixel */
1366 dp += pixel_bytes;
1367 }
1368 break;
1369 }
1370 }
1371 /* set new row width */
1372 row_info->width = (row_info->width +
1373 png_pass_inc[pass] - 1 -
1374 png_pass_start[pass]) /
1375 png_pass_inc[pass];
1376 row_info->rowbytes = ((row_info->width *
1377 row_info->pixel_depth + 7) >> 3);
1378 }
1379 }
1380 #endif
1381
1382 /* This filters the row, chooses which filter to use, if it has not already
1383 * been specified by the application, and then writes the row out with the
1384 * chosen filter.
1385 */
1386 #define PNG_MAXSUM (~((png_uint_32)0) >> 1)
1387 #define PNG_HISHIFT 10
1388 #define PNG_LOMASK ((png_uint_32)0xffffL)
1389 #define PNG_HIMASK ((png_uint_32)(~PNG_LOMASK >> PNG_HISHIFT))
1390 void
1391 png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
1392 {
1393 png_bytep prev_row, best_row, row_buf;
1394 png_uint_32 mins, bpp;
1395
1396 png_debug(1, "in png_write_find_filter\n");
1397 /* find out how many bytes offset each pixel is */
1398 bpp = (row_info->pixel_depth + 7) / 8;
1399
1400 prev_row = png_ptr->prev_row;
1401 best_row = row_buf = png_ptr->row_buf;
1402 mins = PNG_MAXSUM;
1403
1404 /* The prediction method we use is to find which method provides the
1405 * smallest value when summing the absolute values of the distances
1406 * from zero using anything >= 128 as negative numbers. This is known
1407 * as the "minimum sum of absolute differences" heuristic. Other
1408 * heuristics are the "weighted minumum sum of absolute differences"
1409 * (experimental and can in theory improve compression), and the "zlib
1410 * predictive" method (not implemented in libpng 0.95), which does test
1411 * compressions of lines using different filter methods, and then chooses
1412 * the (series of) filter(s) which give minimum compressed data size (VERY
1413 * computationally expensive).
1414 */
1415
1416 /* We don't need to test the 'no filter' case if this is the only filter
1417 * that has been chosen, as it doesn't actually do anything to the data.
1418 */
1419 if (png_ptr->do_filter & PNG_FILTER_NONE &&
1420 png_ptr->do_filter != PNG_FILTER_NONE)
1421 {
1422 png_bytep rp;
1423 png_uint_32 sum = 0;
1424 png_uint_32 i;
1425 int v;
1426
1427 for (i = 0, rp = row_buf + 1; i < row_info->rowbytes; i++, rp++)
1428 {
1429 v = *rp;
1430 sum += (v < 128) ? v : 256 - v;
1431 }
1432
1433 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
1434 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
1435 {
1436 png_uint_32 sumhi, sumlo;
1437 sumlo = sum & PNG_LOMASK;
1438 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; /* Gives us some footroom */
1439
1440 /* Reduce the sum if we match any of the previous rows */
1441 for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++)
1442 {
1443 if (png_ptr->prev_filters[i] == PNG_FILTER_NONE)
1444 {
1445 sumlo = (sumlo * png_ptr->filter_weights[i]) >>
1446 PNG_WEIGHT_SHIFT;
1447 sumhi = (sumhi * png_ptr->filter_weights[i]) >>
1448 PNG_WEIGHT_SHIFT;
1449 }
1450 }
1451
1452 /* Factor in the cost of this filter (this is here for completeness,
1453 * but it makes no sense to have a "cost" for the NONE filter, as
1454 * it has the minimum possible computational cost - none).
1455 */
1456 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
1457 PNG_COST_SHIFT;
1458 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
1459 PNG_COST_SHIFT;
1460
1461 if (sumhi > PNG_HIMASK)
1462 sum = PNG_MAXSUM;
1463 else
1464 sum = (sumhi << PNG_HISHIFT) + sumlo;
1465 }
1466 #endif
1467 mins = sum;
1468 }
1469
1470 /* sub filter */
1471 if (png_ptr->do_filter & PNG_FILTER_SUB)
1472 {
1473 png_bytep rp, dp, lp;
1474 png_uint_32 sum = 0, lmins = mins;
1475 png_uint_32 i;
1476 int v;
1477
1478 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
1479 /* We temporarily increase the "minumum sum" by the factor we
1480 * would reduce the sum of this filter, so that we can do the
1481 * early exit comparison without scaling the sum each time.
1482 */
1483 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
1484 {
1485 png_uint_32 lmhi, lmlo;
1486 lmlo = lmins & PNG_LOMASK;
1487 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
1488
1489 for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++)
1490 {
1491 if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_SUB)
1492 {
1493 lmlo = (lmlo * png_ptr->inv_filter_weights[i]) >>
1494 PNG_WEIGHT_SHIFT;
1495 lmhi = (lmhi * png_ptr->inv_filter_weights[i]) >>
1496 PNG_WEIGHT_SHIFT;
1497 }
1498 }
1499
1500 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
1501 PNG_COST_SHIFT;
1502 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
1503 PNG_COST_SHIFT;
1504
1505 if (lmhi > PNG_HIMASK)
1506 lmins = PNG_MAXSUM;
1507 else
1508 lmins = (lmhi << PNG_HISHIFT) + lmlo;
1509 }
1510 #endif
1511
1512 for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
1513 i++, rp++, dp++)
1514 {
1515 v = *dp = *rp;
1516
1517 sum += (v < 128) ? v : 256 - v;
1518 }
1519 for (lp = row_buf + 1; i < row_info->rowbytes;
1520 i++, rp++, lp++, dp++)
1521 {
1522 v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
1523
1524 sum += (v < 128) ? v : 256 - v;
1525
1526 if (sum > lmins) /* We are already worse, don't continue. */
1527 break;
1528 }
1529
1530 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
1531 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
1532 {
1533 png_uint_32 sumhi, sumlo;
1534 sumlo = sum & PNG_LOMASK;
1535 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
1536
1537 for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++)
1538 {
1539 if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_SUB)
1540 {
1541 sumlo = (sumlo * png_ptr->inv_filter_weights[i]) >>
1542 PNG_WEIGHT_SHIFT;
1543 sumhi = (sumhi * png_ptr->inv_filter_weights[i]) >>
1544 PNG_WEIGHT_SHIFT;
1545 }
1546 }
1547
1548 sumlo = (sumlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
1549 PNG_COST_SHIFT;
1550 sumhi = (sumhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
1551 PNG_COST_SHIFT;
1552
1553 if (sumhi > PNG_HIMASK)
1554 sum = PNG_MAXSUM;
1555 else
1556 sum = (sumhi << PNG_HISHIFT) + sumlo;
1557 }
1558 #endif
1559
1560 if (sum < mins)
1561 {
1562 mins = sum;
1563 best_row = png_ptr->sub_row;
1564 }
1565 }
1566
1567 /* up filter */
1568 if (png_ptr->do_filter & PNG_FILTER_UP)
1569 {
1570 png_bytep rp, dp, pp;
1571 png_uint_32 sum = 0, lmins = mins;
1572 png_uint_32 i;
1573 int v;
1574
1575 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
1576 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
1577 {
1578 png_uint_32 lmhi, lmlo;
1579 lmlo = lmins & PNG_LOMASK;
1580 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
1581
1582 for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++)
1583 {
1584 if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_UP)
1585 {
1586 lmlo = (lmlo * png_ptr->inv_filter_weights[i]) >>
1587 PNG_WEIGHT_SHIFT;
1588 lmhi = (lmhi * png_ptr->inv_filter_weights[i]) >>
1589 PNG_WEIGHT_SHIFT;
1590 }
1591 }
1592
1593 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
1594 PNG_COST_SHIFT;
1595 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
1596 PNG_COST_SHIFT;
1597
1598 if (lmhi > PNG_HIMASK)
1599 lmins = PNG_MAXSUM;
1600 else
1601 lmins = (lmhi << PNG_HISHIFT) + lmlo;
1602 }
1603 #endif
1604
1605 for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
1606 pp = prev_row + 1; i < row_info->rowbytes;
1607 i++, rp++, pp++, dp++)
1608 {
1609 v = *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
1610
1611 sum += (v < 128) ? v : 256 - v;
1612
1613 if (sum > lmins) /* We are already worse, don't continue. */
1614 break;
1615 }
1616
1617 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
1618 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
1619 {
1620 png_uint_32 sumhi, sumlo;
1621 sumlo = sum & PNG_LOMASK;
1622 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
1623
1624 for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++)
1625 {
1626 if (png_ptr->prev_filters[i] == PNG_FILTER_UP)
1627 {
1628 sumlo = (sumlo * png_ptr->filter_weights[i]) >>
1629 PNG_WEIGHT_SHIFT;
1630 sumhi = (sumhi * png_ptr->filter_weights[i]) >>
1631 PNG_WEIGHT_SHIFT;
1632 }
1633 }
1634
1635 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
1636 PNG_COST_SHIFT;
1637 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
1638 PNG_COST_SHIFT;
1639
1640 if (sumhi > PNG_HIMASK)
1641 sum = PNG_MAXSUM;
1642 else
1643 sum = (sumhi << PNG_HISHIFT) + sumlo;
1644 }
1645 #endif
1646
1647 if (sum < mins)
1648 {
1649 mins = sum;
1650 best_row = png_ptr->up_row;
1651 }
1652 }
1653
1654 /* avg filter */
1655 if (png_ptr->do_filter & PNG_FILTER_AVG)
1656 {
1657 png_bytep rp, dp, pp, lp;
1658 png_uint_32 sum = 0, lmins = mins;
1659 png_uint_32 i;
1660 int v;
1661
1662 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
1663 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
1664 {
1665 png_uint_32 lmhi, lmlo;
1666 lmlo = lmins & PNG_LOMASK;
1667 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
1668
1669 for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++)
1670 {
1671 if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_AVG)
1672 {
1673 lmlo = (lmlo * png_ptr->inv_filter_weights[i]) >>
1674 PNG_WEIGHT_SHIFT;
1675 lmhi = (lmhi * png_ptr->inv_filter_weights[i]) >>
1676 PNG_WEIGHT_SHIFT;
1677 }
1678 }
1679
1680 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
1681 PNG_COST_SHIFT;
1682 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
1683 PNG_COST_SHIFT;
1684
1685 if (lmhi > PNG_HIMASK)
1686 lmins = PNG_MAXSUM;
1687 else
1688 lmins = (lmhi << PNG_HISHIFT) + lmlo;
1689 }
1690 #endif
1691
1692 for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
1693 pp = prev_row + 1; i < bpp; i++, rp++, pp++, dp++)
1694 {
1695 v = *dp = (png_byte)(((int)*rp - ((int)*pp / 2)) & 0xff);
1696
1697 sum += (v < 128) ? v : 256 - v;
1698 }
1699 for (lp = row_buf + 1; i < row_info->rowbytes;
1700 i++, rp++, pp++, lp++, dp++)
1701 {
1702 v = *dp = (png_byte)(((int)*rp - (((int)*pp + (int)*lp) / 2)) & 0xff);
1703
1704 sum += (v < 128) ? v : 256 - v;
1705
1706 if (sum > lmins) /* We are already worse, don't continue. */
1707 break;
1708 }
1709
1710 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
1711 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
1712 {
1713 png_uint_32 sumhi, sumlo;
1714 sumlo = sum & PNG_LOMASK;
1715 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
1716
1717 for (i = 0; i < png_ptr->num_prev_filters; i++)
1718 {
1719 if (png_ptr->prev_filters[i] == PNG_FILTER_NONE)
1720 {
1721 sumlo = (sumlo * png_ptr->filter_weights[i]) >>
1722 PNG_WEIGHT_SHIFT;
1723 sumhi = (sumhi * png_ptr->filter_weights[i]) >>
1724 PNG_WEIGHT_SHIFT;
1725 }
1726 }
1727
1728 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
1729 PNG_COST_SHIFT;
1730 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
1731 PNG_COST_SHIFT;
1732
1733 if (sumhi > PNG_HIMASK)
1734 sum = PNG_MAXSUM;
1735 else
1736 sum = (sumhi << PNG_HISHIFT) + sumlo;
1737 }
1738 #endif
1739
1740 if (sum < mins)
1741 {
1742 mins = sum;
1743 best_row = png_ptr->avg_row;
1744 }
1745 }
1746
1747 /* Paeth filter */
1748 if (png_ptr->do_filter & PNG_FILTER_PAETH)
1749 {
1750 png_bytep rp, dp, pp, cp, lp;
1751 png_uint_32 sum = 0, lmins = mins;
1752 png_uint_32 i;
1753 int v;
1754
1755 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
1756 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
1757 {
1758 png_uint_32 lmhi, lmlo;
1759 lmlo = lmins & PNG_LOMASK;
1760 lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
1761
1762 for (i = 0; i < png_ptr->num_prev_filters; i++)
1763 {
1764 if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_PAETH)
1765 {
1766 lmlo = (lmlo * png_ptr->inv_filter_weights[i]) >>
1767 PNG_WEIGHT_SHIFT;
1768 lmhi = (lmhi * png_ptr->inv_filter_weights[i]) >>
1769 PNG_WEIGHT_SHIFT;
1770 }
1771 }
1772
1773 lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
1774 PNG_COST_SHIFT;
1775 lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
1776 PNG_COST_SHIFT;
1777
1778 if (lmhi > PNG_HIMASK)
1779 lmins = PNG_MAXSUM;
1780 else
1781 lmins = (lmhi << PNG_HISHIFT) + lmlo;
1782 }
1783 #endif
1784
1785 for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
1786 pp = prev_row + 1; (unsigned)i < bpp; i++, rp++, pp++, dp++)
1787 {
1788 v = *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
1789
1790 sum += (v < 128) ? v : 256 - v;
1791 }
1792 for (lp = row_buf + 1, cp = prev_row + 1; i < row_info->rowbytes;
1793 i++, rp++, pp++, lp++, dp++, cp++)
1794 {
1795 int a, b, c, pa, pb, pc, p;
1796
1797 b = *pp;
1798 c = *cp;
1799 a = *lp;
1800
1801 p = a + b - c;
1802 pa = abs(p - a);
1803 pb = abs(p - b);
1804 pc = abs(p - c);
1805
1806 if (pa <= pb && pa <= pc)
1807 p = a;
1808 else if (pb <= pc)
1809 p = b;
1810 else
1811 p = c;
1812
1813 v = *dp = (png_byte)(((int)*rp - p) & 0xff);
1814
1815 sum += (v < 128) ? v : 256 - v;
1816
1817 if (sum > lmins) /* We are already worse, don't continue. */
1818 break;
1819 }
1820
1821 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
1822 if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
1823 {
1824 png_uint_32 sumhi, sumlo;
1825 sumlo = sum & PNG_LOMASK;
1826 sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
1827
1828 for (i = 0; i < png_ptr->num_prev_filters; i++)
1829 {
1830 if (png_ptr->prev_filters[i] == PNG_FILTER_PAETH)
1831 {
1832 sumlo = (sumlo * png_ptr->filter_weights[i]) >>
1833 PNG_WEIGHT_SHIFT;
1834 sumhi = (sumhi * png_ptr->filter_weights[i]) >>
1835 PNG_WEIGHT_SHIFT;
1836 }
1837 }
1838
1839 sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
1840 PNG_COST_SHIFT;
1841 sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
1842 PNG_COST_SHIFT;
1843
1844 if (sumhi > PNG_HIMASK)
1845 sum = PNG_MAXSUM;
1846 else
1847 sum = (sumhi << PNG_HISHIFT) + sumlo;
1848 }
1849 #endif
1850
1851 if (sum < mins)
1852 {
1853 best_row = png_ptr->paeth_row;
1854 }
1855 }
1856
1857 /* Do the actual writing of the filtered row data from the chosen filter. */
1858 png_write_filtered_row(png_ptr, best_row);
1859
1860 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
1861 /* Save the type of filter we picked this time for future calculations */
1862 if (png_ptr->num_prev_filters > 0)
1863 {
1864 int i;
1865
1866 for (i = 1; i < (int)png_ptr->num_prev_filters; i++)
1867 {
1868 png_ptr->prev_filters[i] = png_ptr->prev_filters[i - 1];
1869 }
1870 png_ptr->prev_filters[i] = best_row[0];
1871 }
1872 #endif
1873 }
1874
1875
1876 /* Do the actual writing of a previously filtered row. */
1877 void
1878 png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row)
1879 {
1880 png_debug(1, "in png_write_filtered_row\n");
1881 png_debug1(2, "filter = %d\n", filtered_row[0]);
1882 /* set up the zlib input buffer */
1883 png_ptr->zstream.next_in = filtered_row;
1884 png_ptr->zstream.avail_in = (uInt)png_ptr->row_info.rowbytes + 1;
1885 /* repeat until we have compressed all the data */
1886 do
1887 {
1888 int ret; /* return of zlib */
1889
1890 /* compress the data */
1891 ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
1892 /* check for compression errors */
1893 if (ret != Z_OK)
1894 {
1895 if (png_ptr->zstream.msg != NULL)
1896 png_error(png_ptr, png_ptr->zstream.msg);
1897 else
1898 png_error(png_ptr, "zlib error");
1899 }
1900
1901 /* see if it is time to write another IDAT */
1902 if (!(png_ptr->zstream.avail_out))
1903 {
1904 /* write the IDAT and reset the zlib output buffer */
1905 png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
1906 png_ptr->zstream.next_out = png_ptr->zbuf;
1907 png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1908 }
1909 /* repeat until all data has been compressed */
1910 } while (png_ptr->zstream.avail_in);
1911
1912 /* swap the current and previous rows */
1913 if (png_ptr->prev_row != NULL)
1914 {
1915 png_bytep tptr;
1916
1917 tptr = png_ptr->prev_row;
1918 png_ptr->prev_row = png_ptr->row_buf;
1919 png_ptr->row_buf = tptr;
1920 }
1921
1922 /* finish row - updates counters and flushes zlib if last row */
1923 png_write_finish_row(png_ptr);
1924
1925 #if defined(PNG_WRITE_FLUSH_SUPPORTED)
1926 png_ptr->flush_rows++;
1927
1928 if (png_ptr->flush_dist > 0 &&
1929 png_ptr->flush_rows >= png_ptr->flush_dist)
1930 {
1931 png_write_flush(png_ptr);
1932 }
1933 #endif /* PNG_WRITE_FLUSH_SUPPORTED */
1934 }