1
2/* pngwutil.c - utilities to write a PNG file
3 *
4 * Last changed in libpng 1.5.10 [March 8, 2012]
5 * Copyright (c) 1998-2012 Glenn Randers-Pehrson
6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
8 *
9 * This code is released under the libpng license.
10 * For conditions of distribution and use, see the disclaimer
11 * and license in png.h
12 */
13
14#include "pngpriv.h"
15
16#ifdef PNG_WRITE_SUPPORTED
17
18#ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
19/* Place a 32-bit number into a buffer in PNG byte order.  We work
20 * with unsigned numbers for convenience, although one supported
21 * ancillary chunk uses signed (two's complement) numbers.
22 */
23void PNGAPI
24png_save_uint_32(png_bytep buf, png_uint_32 i)
25{
26   buf[0] = (png_byte)((i >> 24) & 0xff);
27   buf[1] = (png_byte)((i >> 16) & 0xff);
28   buf[2] = (png_byte)((i >> 8) & 0xff);
29   buf[3] = (png_byte)(i & 0xff);
30}
31
32#ifdef PNG_SAVE_INT_32_SUPPORTED
33/* The png_save_int_32 function assumes integers are stored in two's
34 * complement format.  If this isn't the case, then this routine needs to
35 * be modified to write data in two's complement format.  Note that,
36 * the following works correctly even if png_int_32 has more than 32 bits
37 * (compare the more complex code required on read for sign extention.)
38 */
39void PNGAPI
40png_save_int_32(png_bytep buf, png_int_32 i)
41{
42   buf[0] = (png_byte)((i >> 24) & 0xff);
43   buf[1] = (png_byte)((i >> 16) & 0xff);
44   buf[2] = (png_byte)((i >> 8) & 0xff);
45   buf[3] = (png_byte)(i & 0xff);
46}
47#endif
48
49/* Place a 16-bit number into a buffer in PNG byte order.
50 * The parameter is declared unsigned int, not png_uint_16,
51 * just to avoid potential problems on pre-ANSI C compilers.
52 */
53void PNGAPI
54png_save_uint_16(png_bytep buf, unsigned int i)
55{
56   buf[0] = (png_byte)((i >> 8) & 0xff);
57   buf[1] = (png_byte)(i & 0xff);
58}
59#endif
60
61/* Simple function to write the signature.  If we have already written
62 * the magic bytes of the signature, or more likely, the PNG stream is
63 * being embedded into another stream and doesn't need its own signature,
64 * we should call png_set_sig_bytes() to tell libpng how many of the
65 * bytes have already been written.
66 */
67void PNGAPI
68png_write_sig(png_structp png_ptr)
69{
70   png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
71
72#ifdef PNG_IO_STATE_SUPPORTED
73   /* Inform the I/O callback that the signature is being written */
74   png_ptr->io_state = PNG_IO_WRITING | PNG_IO_SIGNATURE;
75#endif
76
77   /* Write the rest of the 8 byte signature */
78   png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes],
79      (png_size_t)(8 - png_ptr->sig_bytes));
80
81   if (png_ptr->sig_bytes < 3)
82      png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
83}
84
85/* Write the start of a PNG chunk.  The type is the chunk type.
86 * The total_length is the sum of the lengths of all the data you will be
87 * passing in png_write_chunk_data().
88 */
89static void
90png_write_chunk_header(png_structp png_ptr, png_uint_32 chunk_name,
91    png_uint_32 length)
92{
93   png_byte buf[8];
94
95#if defined(PNG_DEBUG) && (PNG_DEBUG > 0)
96   PNG_CSTRING_FROM_CHUNK(buf, chunk_name);
97   png_debug2(0, "Writing %s chunk, length = %lu", buf, (unsigned long)length);
98#endif
99
100   if (png_ptr == NULL)
101      return;
102
103#ifdef PNG_IO_STATE_SUPPORTED
104   /* Inform the I/O callback that the chunk header is being written.
105    * PNG_IO_CHUNK_HDR requires a single I/O call.
106    */
107   png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_HDR;
108#endif
109
110   /* Write the length and the chunk name */
111   png_save_uint_32(buf, length);
112   png_save_uint_32(buf + 4, chunk_name);
113   png_write_data(png_ptr, buf, 8);
114
115   /* Put the chunk name into png_ptr->chunk_name */
116   png_ptr->chunk_name = chunk_name;
117
118   /* Reset the crc and run it over the chunk name */
119   png_reset_crc(png_ptr);
120
121   png_calculate_crc(png_ptr, buf + 4, 4);
122
123#ifdef PNG_IO_STATE_SUPPORTED
124   /* Inform the I/O callback that chunk data will (possibly) be written.
125    * PNG_IO_CHUNK_DATA does NOT require a specific number of I/O calls.
126    */
127   png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_DATA;
128#endif
129}
130
131void PNGAPI
132png_write_chunk_start(png_structp png_ptr, png_const_bytep chunk_string,
133    png_uint_32 length)
134{
135   png_write_chunk_header(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), length);
136}
137
138/* Write the data of a PNG chunk started with png_write_chunk_header().
139 * Note that multiple calls to this function are allowed, and that the
140 * sum of the lengths from these calls *must* add up to the total_length
141 * given to png_write_chunk_header().
142 */
143void PNGAPI
144png_write_chunk_data(png_structp png_ptr, png_const_bytep data,
145    png_size_t length)
146{
147   /* Write the data, and run the CRC over it */
148   if (png_ptr == NULL)
149      return;
150
151   if (data != NULL && length > 0)
152   {
153      png_write_data(png_ptr, data, length);
154
155      /* Update the CRC after writing the data,
156       * in case that the user I/O routine alters it.
157       */
158      png_calculate_crc(png_ptr, data, length);
159   }
160}
161
162/* Finish a chunk started with png_write_chunk_header(). */
163void PNGAPI
164png_write_chunk_end(png_structp png_ptr)
165{
166   png_byte buf[4];
167
168   if (png_ptr == NULL) return;
169
170#ifdef PNG_IO_STATE_SUPPORTED
171   /* Inform the I/O callback that the chunk CRC is being written.
172    * PNG_IO_CHUNK_CRC requires a single I/O function call.
173    */
174   png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_CRC;
175#endif
176
177   /* Write the crc in a single operation */
178   png_save_uint_32(buf, png_ptr->crc);
179
180   png_write_data(png_ptr, buf, (png_size_t)4);
181}
182
183/* Write a PNG chunk all at once.  The type is an array of ASCII characters
184 * representing the chunk name.  The array must be at least 4 bytes in
185 * length, and does not need to be null terminated.  To be safe, pass the
186 * pre-defined chunk names here, and if you need a new one, define it
187 * where the others are defined.  The length is the length of the data.
188 * All the data must be present.  If that is not possible, use the
189 * png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end()
190 * functions instead.
191 */
192static void
193png_write_complete_chunk(png_structp png_ptr, png_uint_32 chunk_name,
194   png_const_bytep data, png_size_t length)
195{
196   if (png_ptr == NULL)
197      return;
198
199   /* On 64 bit architectures 'length' may not fit in a png_uint_32. */
200   if (length > PNG_UINT_32_MAX)
201      png_error(png_ptr, "length exceeds PNG maxima");
202
203   png_write_chunk_header(png_ptr, chunk_name, (png_uint_32)length);
204   png_write_chunk_data(png_ptr, data, length);
205   png_write_chunk_end(png_ptr);
206}
207
208/* This is the API that calls the internal function above. */
209void PNGAPI
210png_write_chunk(png_structp png_ptr, png_const_bytep chunk_string,
211   png_const_bytep data, png_size_t length)
212{
213   png_write_complete_chunk(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), data,
214      length);
215}
216
217/* Initialize the compressor for the appropriate type of compression. */
218static void
219png_zlib_claim(png_structp png_ptr, png_uint_32 state)
220{
221   if (!(png_ptr->zlib_state & PNG_ZLIB_IN_USE))
222   {
223      /* If already initialized for 'state' do not re-init. */
224      if (png_ptr->zlib_state != state)
225      {
226         int ret = Z_OK;
227         png_const_charp who = "-";
228
229         /* If actually initialized for another state do a deflateEnd. */
230         if (png_ptr->zlib_state != PNG_ZLIB_UNINITIALIZED)
231         {
232            ret = deflateEnd(&png_ptr->zstream);
233            who = "end";
234            png_ptr->zlib_state = PNG_ZLIB_UNINITIALIZED;
235         }
236
237         /* zlib itself detects an incomplete state on deflateEnd */
238         if (ret == Z_OK) switch (state)
239         {
240#           ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
241               case PNG_ZLIB_FOR_TEXT:
242                  ret = deflateInit2(&png_ptr->zstream,
243                     png_ptr->zlib_text_level, png_ptr->zlib_text_method,
244                     png_ptr->zlib_text_window_bits,
245                     png_ptr->zlib_text_mem_level, png_ptr->zlib_text_strategy);
246                  who = "text";
247                  break;
248#           endif
249
250            case PNG_ZLIB_FOR_IDAT:
251               ret = deflateInit2(&png_ptr->zstream, png_ptr->zlib_level,
252                   png_ptr->zlib_method, png_ptr->zlib_window_bits,
253                   png_ptr->zlib_mem_level, png_ptr->zlib_strategy);
254               who = "IDAT";
255               break;
256
257            default:
258               png_error(png_ptr, "invalid zlib state");
259         }
260
261         if (ret == Z_OK)
262            png_ptr->zlib_state = state;
263
264         else /* an error in deflateEnd or deflateInit2 */
265         {
266            size_t pos = 0;
267            char msg[64];
268
269            pos = png_safecat(msg, sizeof msg, pos,
270               "zlib failed to initialize compressor (");
271            pos = png_safecat(msg, sizeof msg, pos, who);
272
273            switch (ret)
274            {
275               case Z_VERSION_ERROR:
276                  pos = png_safecat(msg, sizeof msg, pos, ") version error");
277                  break;
278
279               case Z_STREAM_ERROR:
280                  pos = png_safecat(msg, sizeof msg, pos, ") stream error");
281                  break;
282
283               case Z_MEM_ERROR:
284                  pos = png_safecat(msg, sizeof msg, pos, ") memory error");
285                  break;
286
287               default:
288                  pos = png_safecat(msg, sizeof msg, pos, ") unknown error");
289                  break;
290            }
291
292            png_error(png_ptr, msg);
293         }
294      }
295
296      /* Here on success, claim the zstream: */
297      png_ptr->zlib_state |= PNG_ZLIB_IN_USE;
298   }
299
300   else
301      png_error(png_ptr, "zstream already in use (internal error)");
302}
303
304/* The opposite: release the stream.  It is also reset, this API will warn on
305 * error but will not fail.
306 */
307static void
308png_zlib_release(png_structp png_ptr)
309{
310   if (png_ptr->zlib_state & PNG_ZLIB_IN_USE)
311   {
312      int ret = deflateReset(&png_ptr->zstream);
313
314      png_ptr->zlib_state &= ~PNG_ZLIB_IN_USE;
315
316      if (ret != Z_OK)
317      {
318         png_const_charp err;
319         PNG_WARNING_PARAMETERS(p)
320
321         switch (ret)
322         {
323            case Z_VERSION_ERROR:
324               err = "version";
325               break;
326
327            case Z_STREAM_ERROR:
328               err = "stream";
329               break;
330
331            case Z_MEM_ERROR:
332               err = "memory";
333               break;
334
335            default:
336               err = "unknown";
337               break;
338         }
339
340         png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_d, ret);
341         png_warning_parameter(p, 2, err);
342
343         if (png_ptr->zstream.msg)
344            err = png_ptr->zstream.msg;
345         else
346            err = "[no zlib message]";
347
348         png_warning_parameter(p, 3, err);
349
350         png_formatted_warning(png_ptr, p,
351            "zlib failed to reset compressor: @1(@2): @3");
352      }
353   }
354
355   else
356      png_warning(png_ptr, "zstream not in use (internal error)");
357}
358
359#ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
360/* This pair of functions encapsulates the operation of (a) compressing a
361 * text string, and (b) issuing it later as a series of chunk data writes.
362 * The compression_state structure is shared context for these functions
363 * set up by the caller in order to make the whole mess thread-safe.
364 */
365
366typedef struct
367{
368   png_const_bytep input;   /* The uncompressed input data */
369   png_size_t input_len;    /* Its length */
370   int num_output_ptr;      /* Number of output pointers used */
371   int max_output_ptr;      /* Size of output_ptr */
372   png_bytep *output_ptr;   /* Array of pointers to output */
373} compression_state;
374
375/* Compress given text into storage in the png_ptr structure */
376static int /* PRIVATE */
377png_text_compress(png_structp png_ptr,
378    png_const_charp text, png_size_t text_len, int compression,
379    compression_state *comp)
380{
381   int ret;
382
383   comp->num_output_ptr = 0;
384   comp->max_output_ptr = 0;
385   comp->output_ptr = NULL;
386   comp->input = NULL;
387   comp->input_len = text_len;
388
389   /* We may just want to pass the text right through */
390   if (compression == PNG_TEXT_COMPRESSION_NONE)
391   {
392      comp->input = (png_const_bytep)text;
393      return((int)text_len);
394   }
395
396   if (compression >= PNG_TEXT_COMPRESSION_LAST)
397   {
398      PNG_WARNING_PARAMETERS(p)
399
400      png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_d,
401         compression);
402      png_formatted_warning(png_ptr, p, "Unknown compression type @1");
403   }
404
405   /* We can't write the chunk until we find out how much data we have,
406    * which means we need to run the compressor first and save the
407    * output.  This shouldn't be a problem, as the vast majority of
408    * comments should be reasonable, but we will set up an array of
409    * malloc'd pointers to be sure.
410    *
411    * If we knew the application was well behaved, we could simplify this
412    * greatly by assuming we can always malloc an output buffer large
413    * enough to hold the compressed text ((1001 * text_len / 1000) + 12)
414    * and malloc this directly.  The only time this would be a bad idea is
415    * if we can't malloc more than 64K and we have 64K of random input
416    * data, or if the input string is incredibly large (although this
417    * wouldn't cause a failure, just a slowdown due to swapping).
418    */
419   png_zlib_claim(png_ptr, PNG_ZLIB_FOR_TEXT);
420
421   /* Set up the compression buffers */
422   /* TODO: the following cast hides a potential overflow problem. */
423   png_ptr->zstream.avail_in = (uInt)text_len;
424
425   /* NOTE: assume zlib doesn't overwrite the input */
426   png_ptr->zstream.next_in = (Bytef *)text;
427   png_ptr->zstream.avail_out = png_ptr->zbuf_size;
428   png_ptr->zstream.next_out = png_ptr->zbuf;
429
430   /* This is the same compression loop as in png_write_row() */
431   do
432   {
433      /* Compress the data */
434      ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
435
436      if (ret != Z_OK)
437      {
438         /* Error */
439         if (png_ptr->zstream.msg != NULL)
440            png_error(png_ptr, png_ptr->zstream.msg);
441
442         else
443            png_error(png_ptr, "zlib error");
444      }
445
446      /* Check to see if we need more room */
447      if (!(png_ptr->zstream.avail_out))
448      {
449         /* Make sure the output array has room */
450         if (comp->num_output_ptr >= comp->max_output_ptr)
451         {
452            int old_max;
453
454            old_max = comp->max_output_ptr;
455            comp->max_output_ptr = comp->num_output_ptr + 4;
456            if (comp->output_ptr != NULL)
457            {
458               png_bytepp old_ptr;
459
460               old_ptr = comp->output_ptr;
461
462               comp->output_ptr = (png_bytepp)png_malloc(png_ptr,
463                   (png_alloc_size_t)
464                   (comp->max_output_ptr * png_sizeof(png_charpp)));
465
466               png_memcpy(comp->output_ptr, old_ptr, old_max
467                   * png_sizeof(png_charp));
468
469               png_free(png_ptr, old_ptr);
470            }
471            else
472               comp->output_ptr = (png_bytepp)png_malloc(png_ptr,
473                   (png_alloc_size_t)
474                   (comp->max_output_ptr * png_sizeof(png_charp)));
475         }
476
477         /* Save the data */
478         comp->output_ptr[comp->num_output_ptr] =
479             (png_bytep)png_malloc(png_ptr,
480             (png_alloc_size_t)png_ptr->zbuf_size);
481
482         png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
483             png_ptr->zbuf_size);
484
485         comp->num_output_ptr++;
486
487         /* and reset the buffer */
488         png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
489         png_ptr->zstream.next_out = png_ptr->zbuf;
490      }
491   /* Continue until we don't have any more to compress */
492   } while (png_ptr->zstream.avail_in);
493
494   /* Finish the compression */
495   do
496   {
497      /* Tell zlib we are finished */
498      ret = deflate(&png_ptr->zstream, Z_FINISH);
499
500      if (ret == Z_OK)
501      {
502         /* Check to see if we need more room */
503         if (!(png_ptr->zstream.avail_out))
504         {
505            /* Check to make sure our output array has room */
506            if (comp->num_output_ptr >= comp->max_output_ptr)
507            {
508               int old_max;
509
510               old_max = comp->max_output_ptr;
511               comp->max_output_ptr = comp->num_output_ptr + 4;
512               if (comp->output_ptr != NULL)
513               {
514                  png_bytepp old_ptr;
515
516                  old_ptr = comp->output_ptr;
517
518                  /* This could be optimized to realloc() */
519                  comp->output_ptr = (png_bytepp)png_malloc(png_ptr,
520                      (png_alloc_size_t)(comp->max_output_ptr *
521                      png_sizeof(png_charp)));
522
523                  png_memcpy(comp->output_ptr, old_ptr,
524                      old_max * png_sizeof(png_charp));
525
526                  png_free(png_ptr, old_ptr);
527               }
528
529               else
530                  comp->output_ptr = (png_bytepp)png_malloc(png_ptr,
531                      (png_alloc_size_t)(comp->max_output_ptr *
532                      png_sizeof(png_charp)));
533            }
534
535            /* Save the data */
536            comp->output_ptr[comp->num_output_ptr] =
537                (png_bytep)png_malloc(png_ptr,
538                (png_alloc_size_t)png_ptr->zbuf_size);
539
540            png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
541                png_ptr->zbuf_size);
542
543            comp->num_output_ptr++;
544
545            /* and reset the buffer pointers */
546            png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
547            png_ptr->zstream.next_out = png_ptr->zbuf;
548         }
549      }
550      else if (ret != Z_STREAM_END)
551      {
552         /* We got an error */
553         if (png_ptr->zstream.msg != NULL)
554            png_error(png_ptr, png_ptr->zstream.msg);
555
556         else
557            png_error(png_ptr, "zlib error");
558      }
559   } while (ret != Z_STREAM_END);
560
561   /* Text length is number of buffers plus last buffer */
562   text_len = png_ptr->zbuf_size * comp->num_output_ptr;
563
564   if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
565      text_len += png_ptr->zbuf_size - (png_size_t)png_ptr->zstream.avail_out;
566
567   return((int)text_len);
568}
569
570/* Ship the compressed text out via chunk writes */
571static void /* PRIVATE */
572png_write_compressed_data_out(png_structp png_ptr, compression_state *comp,
573   png_size_t data_len)
574{
575   int i;
576
577   /* Handle the no-compression case */
578   if (comp->input)
579   {
580      png_write_chunk_data(png_ptr, comp->input, data_len);
581
582      return;
583   }
584
585#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
586   /* The zbuf_size test is because the code below doesn't work if zbuf_size is
587    * '1'; simply skip it to avoid memory overwrite.
588    */
589   if (data_len >= 2 && comp->input_len < 16384 && png_ptr->zbuf_size > 1)
590   {
591      unsigned int z_cmf;  /* zlib compression method and flags */
592
593      /* Optimize the CMF field in the zlib stream.  This hack of the zlib
594       * stream is compliant to the stream specification.
595       */
596
597      if (comp->num_output_ptr)
598        z_cmf = comp->output_ptr[0][0];
599      else
600        z_cmf = png_ptr->zbuf[0];
601
602      if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
603      {
604         unsigned int z_cinfo;
605         unsigned int half_z_window_size;
606         png_size_t uncompressed_text_size = comp->input_len;
607
608         z_cinfo = z_cmf >> 4;
609         half_z_window_size = 1 << (z_cinfo + 7);
610
611         while (uncompressed_text_size <= half_z_window_size &&
612             half_z_window_size >= 256)
613         {
614            z_cinfo--;
615            half_z_window_size >>= 1;
616         }
617
618         z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
619
620         if (comp->num_output_ptr)
621         {
622
623           if (comp->output_ptr[0][0] != z_cmf)
624           {
625              int tmp;
626
627              comp->output_ptr[0][0] = (png_byte)z_cmf;
628              tmp = comp->output_ptr[0][1] & 0xe0;
629              tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
630              comp->output_ptr[0][1] = (png_byte)tmp;
631           }
632         }
633         else
634         {
635            int tmp;
636
637            png_ptr->zbuf[0] = (png_byte)z_cmf;
638            tmp = png_ptr->zbuf[1] & 0xe0;
639            tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
640            png_ptr->zbuf[1] = (png_byte)tmp;
641         }
642      }
643
644      else
645         png_error(png_ptr,
646             "Invalid zlib compression method or flags in non-IDAT chunk");
647   }
648#endif /* PNG_WRITE_OPTIMIZE_CMF_SUPPORTED */
649
650   /* Write saved output buffers, if any */
651   for (i = 0; i < comp->num_output_ptr; i++)
652   {
653      png_write_chunk_data(png_ptr, comp->output_ptr[i],
654          (png_size_t)png_ptr->zbuf_size);
655
656      png_free(png_ptr, comp->output_ptr[i]);
657   }
658
659   if (comp->max_output_ptr != 0)
660      png_free(png_ptr, comp->output_ptr);
661
662   /* Write anything left in zbuf */
663   if (png_ptr->zstream.avail_out < (png_uint_32)png_ptr->zbuf_size)
664      png_write_chunk_data(png_ptr, png_ptr->zbuf,
665          (png_size_t)(png_ptr->zbuf_size - png_ptr->zstream.avail_out));
666
667   /* Reset zlib for another zTXt/iTXt or image data */
668   png_zlib_release(png_ptr);
669}
670#endif /* PNG_WRITE_COMPRESSED_TEXT_SUPPORTED */
671
672/* Write the IHDR chunk, and update the png_struct with the necessary
673 * information.  Note that the rest of this code depends upon this
674 * information being correct.
675 */
676void /* PRIVATE */
677png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
678    int bit_depth, int color_type, int compression_type, int filter_type,
679    int interlace_type)
680{
681   png_byte buf[13]; /* Buffer to store the IHDR info */
682
683   png_debug(1, "in png_write_IHDR");
684
685   /* Check that we have valid input data from the application info */
686   switch (color_type)
687   {
688      case PNG_COLOR_TYPE_GRAY:
689         switch (bit_depth)
690         {
691            case 1:
692            case 2:
693            case 4:
694            case 8:
695#ifdef PNG_WRITE_16BIT_SUPPORTED
696            case 16:
697#endif
698               png_ptr->channels = 1; break;
699
700            default:
701               png_error(png_ptr,
702                   "Invalid bit depth for grayscale image");
703         }
704         break;
705
706      case PNG_COLOR_TYPE_RGB:
707#ifdef PNG_WRITE_16BIT_SUPPORTED
708         if (bit_depth != 8 && bit_depth != 16)
709#else
710         if (bit_depth != 8)
711#endif
712            png_error(png_ptr, "Invalid bit depth for RGB image");
713
714         png_ptr->channels = 3;
715         break;
716
717      case PNG_COLOR_TYPE_PALETTE:
718         switch (bit_depth)
719         {
720            case 1:
721            case 2:
722            case 4:
723            case 8:
724               png_ptr->channels = 1;
725               break;
726
727            default:
728               png_error(png_ptr, "Invalid bit depth for paletted image");
729         }
730         break;
731
732      case PNG_COLOR_TYPE_GRAY_ALPHA:
733         if (bit_depth != 8 && bit_depth != 16)
734            png_error(png_ptr, "Invalid bit depth for grayscale+alpha image");
735
736         png_ptr->channels = 2;
737         break;
738
739      case PNG_COLOR_TYPE_RGB_ALPHA:
740#ifdef PNG_WRITE_16BIT_SUPPORTED
741         if (bit_depth != 8 && bit_depth != 16)
742#else
743         if (bit_depth != 8)
744#endif
745            png_error(png_ptr, "Invalid bit depth for RGBA image");
746
747         png_ptr->channels = 4;
748         break;
749
750      default:
751         png_error(png_ptr, "Invalid image color type specified");
752   }
753
754   if (compression_type != PNG_COMPRESSION_TYPE_BASE)
755   {
756      png_warning(png_ptr, "Invalid compression type specified");
757      compression_type = PNG_COMPRESSION_TYPE_BASE;
758   }
759
760   /* Write filter_method 64 (intrapixel differencing) only if
761    * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
762    * 2. Libpng did not write a PNG signature (this filter_method is only
763    *    used in PNG datastreams that are embedded in MNG datastreams) and
764    * 3. The application called png_permit_mng_features with a mask that
765    *    included PNG_FLAG_MNG_FILTER_64 and
766    * 4. The filter_method is 64 and
767    * 5. The color_type is RGB or RGBA
768    */
769   if (
770#ifdef PNG_MNG_FEATURES_SUPPORTED
771       !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
772       ((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE) == 0) &&
773       (color_type == PNG_COLOR_TYPE_RGB ||
774        color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&
775       (filter_type == PNG_INTRAPIXEL_DIFFERENCING)) &&
776#endif
777       filter_type != PNG_FILTER_TYPE_BASE)
778   {
779      png_warning(png_ptr, "Invalid filter type specified");
780      filter_type = PNG_FILTER_TYPE_BASE;
781   }
782
783#ifdef PNG_WRITE_INTERLACING_SUPPORTED
784   if (interlace_type != PNG_INTERLACE_NONE &&
785       interlace_type != PNG_INTERLACE_ADAM7)
786   {
787      png_warning(png_ptr, "Invalid interlace type specified");
788      interlace_type = PNG_INTERLACE_ADAM7;
789   }
790#else
791   interlace_type=PNG_INTERLACE_NONE;
792#endif
793
794   /* Save the relevent information */
795   png_ptr->bit_depth = (png_byte)bit_depth;
796   png_ptr->color_type = (png_byte)color_type;
797   png_ptr->interlaced = (png_byte)interlace_type;
798#ifdef PNG_MNG_FEATURES_SUPPORTED
799   png_ptr->filter_type = (png_byte)filter_type;
800#endif
801   png_ptr->compression_type = (png_byte)compression_type;
802   png_ptr->width = width;
803   png_ptr->height = height;
804
805   png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels);
806   png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width);
807   /* Set the usr info, so any transformations can modify it */
808   png_ptr->usr_width = png_ptr->width;
809   png_ptr->usr_bit_depth = png_ptr->bit_depth;
810   png_ptr->usr_channels = png_ptr->channels;
811
812   /* Pack the header information into the buffer */
813   png_save_uint_32(buf, width);
814   png_save_uint_32(buf + 4, height);
815   buf[8] = (png_byte)bit_depth;
816   buf[9] = (png_byte)color_type;
817   buf[10] = (png_byte)compression_type;
818   buf[11] = (png_byte)filter_type;
819   buf[12] = (png_byte)interlace_type;
820
821   /* Write the chunk */
822   png_write_complete_chunk(png_ptr, png_IHDR, buf, (png_size_t)13);
823
824   /* Initialize zlib with PNG info */
825   png_ptr->zstream.zalloc = png_zalloc;
826   png_ptr->zstream.zfree = png_zfree;
827   png_ptr->zstream.opaque = (voidpf)png_ptr;
828
829   if (!(png_ptr->do_filter))
830   {
831      if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
832          png_ptr->bit_depth < 8)
833         png_ptr->do_filter = PNG_FILTER_NONE;
834
835      else
836         png_ptr->do_filter = PNG_ALL_FILTERS;
837   }
838
839   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY))
840   {
841      if (png_ptr->do_filter != PNG_FILTER_NONE)
842         png_ptr->zlib_strategy = Z_FILTERED;
843
844      else
845         png_ptr->zlib_strategy = Z_DEFAULT_STRATEGY;
846   }
847
848   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_LEVEL))
849      png_ptr->zlib_level = Z_DEFAULT_COMPRESSION;
850
851   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL))
852      png_ptr->zlib_mem_level = 8;
853
854   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS))
855      png_ptr->zlib_window_bits = 15;
856
857   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_METHOD))
858      png_ptr->zlib_method = 8;
859
860#ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
861#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
862   if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_STRATEGY))
863      png_ptr->zlib_text_strategy = Z_DEFAULT_STRATEGY;
864
865   if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_LEVEL))
866      png_ptr->zlib_text_level = png_ptr->zlib_level;
867
868   if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_MEM_LEVEL))
869      png_ptr->zlib_text_mem_level = png_ptr->zlib_mem_level;
870
871   if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_WINDOW_BITS))
872      png_ptr->zlib_text_window_bits = png_ptr->zlib_window_bits;
873
874   if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_METHOD))
875      png_ptr->zlib_text_method = png_ptr->zlib_method;
876#else
877   png_ptr->zlib_text_strategy = Z_DEFAULT_STRATEGY;
878   png_ptr->zlib_text_level = png_ptr->zlib_level;
879   png_ptr->zlib_text_mem_level = png_ptr->zlib_mem_level;
880   png_ptr->zlib_text_window_bits = png_ptr->zlib_window_bits;
881   png_ptr->zlib_text_method = png_ptr->zlib_method;
882#endif /* PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED */
883#endif /* PNG_WRITE_COMPRESSED_TEXT_SUPPORTED */
884
885   /* Record that the compressor has not yet been initialized. */
886   png_ptr->zlib_state = PNG_ZLIB_UNINITIALIZED;
887
888   png_ptr->mode = PNG_HAVE_IHDR; /* not READY_FOR_ZTXT */
889}
890
891/* Write the palette.  We are careful not to trust png_color to be in the
892 * correct order for PNG, so people can redefine it to any convenient
893 * structure.
894 */
895void /* PRIVATE */
896png_write_PLTE(png_structp png_ptr, png_const_colorp palette,
897    png_uint_32 num_pal)
898{
899   png_uint_32 i;
900   png_const_colorp pal_ptr;
901   png_byte buf[3];
902
903   png_debug(1, "in png_write_PLTE");
904
905   if ((
906#ifdef PNG_MNG_FEATURES_SUPPORTED
907       !(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) &&
908#endif
909       num_pal == 0) || num_pal > 256)
910   {
911      if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
912      {
913         png_error(png_ptr, "Invalid number of colors in palette");
914      }
915
916      else
917      {
918         png_warning(png_ptr, "Invalid number of colors in palette");
919         return;
920      }
921   }
922
923   if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))
924   {
925      png_warning(png_ptr,
926          "Ignoring request to write a PLTE chunk in grayscale PNG");
927
928      return;
929   }
930
931   png_ptr->num_palette = (png_uint_16)num_pal;
932   png_debug1(3, "num_palette = %d", png_ptr->num_palette);
933
934   png_write_chunk_header(png_ptr, png_PLTE, (png_uint_32)(num_pal * 3));
935#ifdef PNG_POINTER_INDEXING_SUPPORTED
936
937   for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++)
938   {
939      buf[0] = pal_ptr->red;
940      buf[1] = pal_ptr->green;
941      buf[2] = pal_ptr->blue;
942      png_write_chunk_data(png_ptr, buf, (png_size_t)3);
943   }
944
945#else
946   /* This is a little slower but some buggy compilers need to do this
947    * instead
948    */
949   pal_ptr=palette;
950
951   for (i = 0; i < num_pal; i++)
952   {
953      buf[0] = pal_ptr[i].red;
954      buf[1] = pal_ptr[i].green;
955      buf[2] = pal_ptr[i].blue;
956      png_write_chunk_data(png_ptr, buf, (png_size_t)3);
957   }
958
959#endif
960   png_write_chunk_end(png_ptr);
961   png_ptr->mode |= PNG_HAVE_PLTE;
962}
963
964/* Write an IDAT chunk */
965void /* PRIVATE */
966png_write_IDAT(png_structp png_ptr, png_bytep data, png_size_t length)
967{
968   png_debug(1, "in png_write_IDAT");
969
970#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
971   if (!(png_ptr->mode & PNG_HAVE_IDAT) &&
972       png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
973   {
974      /* Optimize the CMF field in the zlib stream.  This hack of the zlib
975       * stream is compliant to the stream specification.
976       */
977      unsigned int z_cmf = data[0];  /* zlib compression method and flags */
978
979      if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
980      {
981         /* Avoid memory underflows and multiplication overflows.
982          *
983          * The conditions below are practically always satisfied;
984          * however, they still must be checked.
985          */
986         if (length >= 2 &&
987             png_ptr->height < 16384 && png_ptr->width < 16384)
988         {
989            /* Compute the maximum possible length of the datastream */
990
991            /* Number of pixels, plus for each row a filter byte
992             * and possibly a padding byte, so increase the maximum
993             * size to account for these.
994             */
995            unsigned int z_cinfo;
996            unsigned int half_z_window_size;
997            png_uint_32 uncompressed_idat_size = png_ptr->height *
998                ((png_ptr->width *
999                png_ptr->channels * png_ptr->bit_depth + 15) >> 3);
1000
1001            /* If it's interlaced, each block of 8 rows is sent as up to
1002             * 14 rows, i.e., 6 additional rows, each with a filter byte
1003             * and possibly a padding byte
1004             */
1005            if (png_ptr->interlaced)
1006               uncompressed_idat_size += ((png_ptr->height + 7)/8) *
1007                   (png_ptr->bit_depth < 8 ? 12 : 6);
1008
1009            z_cinfo = z_cmf >> 4;
1010            half_z_window_size = 1 << (z_cinfo + 7);
1011
1012            while (uncompressed_idat_size <= half_z_window_size &&
1013                half_z_window_size >= 256)
1014            {
1015               z_cinfo--;
1016               half_z_window_size >>= 1;
1017            }
1018
1019            z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
1020
1021            if (data[0] != z_cmf)
1022            {
1023               int tmp;
1024               data[0] = (png_byte)z_cmf;
1025               tmp = data[1] & 0xe0;
1026               tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
1027               data[1] = (png_byte)tmp;
1028            }
1029         }
1030      }
1031
1032      else
1033         png_error(png_ptr,
1034             "Invalid zlib compression method or flags in IDAT");
1035   }
1036#endif /* PNG_WRITE_OPTIMIZE_CMF_SUPPORTED */
1037
1038   png_write_complete_chunk(png_ptr, png_IDAT, data, length);
1039   png_ptr->mode |= PNG_HAVE_IDAT;
1040
1041   /* Prior to 1.5.4 this code was replicated in every caller (except at the
1042    * end, where it isn't technically necessary).  Since this function has
1043    * flushed the data we can safely reset the zlib output buffer here.
1044    */
1045   png_ptr->zstream.next_out = png_ptr->zbuf;
1046   png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1047}
1048
1049/* Write an IEND chunk */
1050void /* PRIVATE */
1051png_write_IEND(png_structp png_ptr)
1052{
1053   png_debug(1, "in png_write_IEND");
1054
1055   png_write_complete_chunk(png_ptr, png_IEND, NULL, (png_size_t)0);
1056   png_ptr->mode |= PNG_HAVE_IEND;
1057}
1058
1059#ifdef PNG_WRITE_gAMA_SUPPORTED
1060/* Write a gAMA chunk */
1061void /* PRIVATE */
1062png_write_gAMA_fixed(png_structp png_ptr, png_fixed_point file_gamma)
1063{
1064   png_byte buf[4];
1065
1066   png_debug(1, "in png_write_gAMA");
1067
1068   /* file_gamma is saved in 1/100,000ths */
1069   png_save_uint_32(buf, (png_uint_32)file_gamma);
1070   png_write_complete_chunk(png_ptr, png_gAMA, buf, (png_size_t)4);
1071}
1072#endif
1073
1074#ifdef PNG_WRITE_sRGB_SUPPORTED
1075/* Write a sRGB chunk */
1076void /* PRIVATE */
1077png_write_sRGB(png_structp png_ptr, int srgb_intent)
1078{
1079   png_byte buf[1];
1080
1081   png_debug(1, "in png_write_sRGB");
1082
1083   if (srgb_intent >= PNG_sRGB_INTENT_LAST)
1084      png_warning(png_ptr,
1085          "Invalid sRGB rendering intent specified");
1086
1087   buf[0]=(png_byte)srgb_intent;
1088   png_write_complete_chunk(png_ptr, png_sRGB, buf, (png_size_t)1);
1089}
1090#endif
1091
1092#ifdef PNG_WRITE_iCCP_SUPPORTED
1093/* Write an iCCP chunk */
1094void /* PRIVATE */
1095png_write_iCCP(png_structp png_ptr, png_const_charp name, int compression_type,
1096    png_const_charp profile, int profile_len)
1097{
1098   png_size_t name_len;
1099   png_charp new_name;
1100   compression_state comp;
1101   int embedded_profile_len = 0;
1102
1103   png_debug(1, "in png_write_iCCP");
1104
1105   comp.num_output_ptr = 0;
1106   comp.max_output_ptr = 0;
1107   comp.output_ptr = NULL;
1108   comp.input = NULL;
1109   comp.input_len = 0;
1110
1111   if ((name_len = png_check_keyword(png_ptr, name, &new_name)) == 0)
1112      return;
1113
1114   if (compression_type != PNG_COMPRESSION_TYPE_BASE)
1115      png_warning(png_ptr, "Unknown compression type in iCCP chunk");
1116
1117   if (profile == NULL)
1118      profile_len = 0;
1119
1120   if (profile_len > 3)
1121      embedded_profile_len =
1122          ((*( (png_const_bytep)profile    ))<<24) |
1123          ((*( (png_const_bytep)profile + 1))<<16) |
1124          ((*( (png_const_bytep)profile + 2))<< 8) |
1125          ((*( (png_const_bytep)profile + 3))    );
1126
1127   if (embedded_profile_len < 0)
1128   {
1129      png_warning(png_ptr,
1130          "Embedded profile length in iCCP chunk is negative");
1131
1132      png_free(png_ptr, new_name);
1133      return;
1134   }
1135
1136   if (profile_len < embedded_profile_len)
1137   {
1138      png_warning(png_ptr,
1139          "Embedded profile length too large in iCCP chunk");
1140
1141      png_free(png_ptr, new_name);
1142      return;
1143   }
1144
1145   if (profile_len > embedded_profile_len)
1146   {
1147      png_warning(png_ptr,
1148          "Truncating profile to actual length in iCCP chunk");
1149
1150      profile_len = embedded_profile_len;
1151   }
1152
1153   if (profile_len)
1154      profile_len = png_text_compress(png_ptr, profile,
1155          (png_size_t)profile_len, PNG_COMPRESSION_TYPE_BASE, &comp);
1156
1157   /* Make sure we include the NULL after the name and the compression type */
1158   png_write_chunk_header(png_ptr, png_iCCP,
1159       (png_uint_32)(name_len + profile_len + 2));
1160
1161   new_name[name_len + 1] = 0x00;
1162
1163   png_write_chunk_data(png_ptr, (png_bytep)new_name,
1164       (png_size_t)(name_len + 2));
1165
1166   if (profile_len)
1167   {
1168      png_write_compressed_data_out(png_ptr, &comp, profile_len);
1169   }
1170
1171   png_write_chunk_end(png_ptr);
1172   png_free(png_ptr, new_name);
1173}
1174#endif
1175
1176#ifdef PNG_WRITE_sPLT_SUPPORTED
1177/* Write a sPLT chunk */
1178void /* PRIVATE */
1179png_write_sPLT(png_structp png_ptr, png_const_sPLT_tp spalette)
1180{
1181   png_size_t name_len;
1182   png_charp new_name;
1183   png_byte entrybuf[10];
1184   png_size_t entry_size = (spalette->depth == 8 ? 6 : 10);
1185   png_size_t palette_size = entry_size * spalette->nentries;
1186   png_sPLT_entryp ep;
1187#ifndef PNG_POINTER_INDEXING_SUPPORTED
1188   int i;
1189#endif
1190
1191   png_debug(1, "in png_write_sPLT");
1192
1193   if ((name_len = png_check_keyword(png_ptr,spalette->name, &new_name))==0)
1194      return;
1195
1196   /* Make sure we include the NULL after the name */
1197   png_write_chunk_header(png_ptr, png_sPLT,
1198       (png_uint_32)(name_len + 2 + palette_size));
1199
1200   png_write_chunk_data(png_ptr, (png_bytep)new_name,
1201       (png_size_t)(name_len + 1));
1202
1203   png_write_chunk_data(png_ptr, &spalette->depth, (png_size_t)1);
1204
1205   /* Loop through each palette entry, writing appropriately */
1206#ifdef PNG_POINTER_INDEXING_SUPPORTED
1207   for (ep = spalette->entries; ep<spalette->entries + spalette->nentries; ep++)
1208   {
1209      if (spalette->depth == 8)
1210      {
1211         entrybuf[0] = (png_byte)ep->red;
1212         entrybuf[1] = (png_byte)ep->green;
1213         entrybuf[2] = (png_byte)ep->blue;
1214         entrybuf[3] = (png_byte)ep->alpha;
1215         png_save_uint_16(entrybuf + 4, ep->frequency);
1216      }
1217
1218      else
1219      {
1220         png_save_uint_16(entrybuf + 0, ep->red);
1221         png_save_uint_16(entrybuf + 2, ep->green);
1222         png_save_uint_16(entrybuf + 4, ep->blue);
1223         png_save_uint_16(entrybuf + 6, ep->alpha);
1224         png_save_uint_16(entrybuf + 8, ep->frequency);
1225      }
1226
1227      png_write_chunk_data(png_ptr, entrybuf, (png_size_t)entry_size);
1228   }
1229#else
1230   ep=spalette->entries;
1231   for (i = 0; i>spalette->nentries; i++)
1232   {
1233      if (spalette->depth == 8)
1234      {
1235         entrybuf[0] = (png_byte)ep[i].red;
1236         entrybuf[1] = (png_byte)ep[i].green;
1237         entrybuf[2] = (png_byte)ep[i].blue;
1238         entrybuf[3] = (png_byte)ep[i].alpha;
1239         png_save_uint_16(entrybuf + 4, ep[i].frequency);
1240      }
1241
1242      else
1243      {
1244         png_save_uint_16(entrybuf + 0, ep[i].red);
1245         png_save_uint_16(entrybuf + 2, ep[i].green);
1246         png_save_uint_16(entrybuf + 4, ep[i].blue);
1247         png_save_uint_16(entrybuf + 6, ep[i].alpha);
1248         png_save_uint_16(entrybuf + 8, ep[i].frequency);
1249      }
1250
1251      png_write_chunk_data(png_ptr, entrybuf, (png_size_t)entry_size);
1252   }
1253#endif
1254
1255   png_write_chunk_end(png_ptr);
1256   png_free(png_ptr, new_name);
1257}
1258#endif
1259
1260#ifdef PNG_WRITE_sBIT_SUPPORTED
1261/* Write the sBIT chunk */
1262void /* PRIVATE */
1263png_write_sBIT(png_structp png_ptr, png_const_color_8p sbit, int color_type)
1264{
1265   png_byte buf[4];
1266   png_size_t size;
1267
1268   png_debug(1, "in png_write_sBIT");
1269
1270   /* Make sure we don't depend upon the order of PNG_COLOR_8 */
1271   if (color_type & PNG_COLOR_MASK_COLOR)
1272   {
1273      png_byte maxbits;
1274
1275      maxbits = (png_byte)(color_type==PNG_COLOR_TYPE_PALETTE ? 8 :
1276          png_ptr->usr_bit_depth);
1277
1278      if (sbit->red == 0 || sbit->red > maxbits ||
1279          sbit->green == 0 || sbit->green > maxbits ||
1280          sbit->blue == 0 || sbit->blue > maxbits)
1281      {
1282         png_warning(png_ptr, "Invalid sBIT depth specified");
1283         return;
1284      }
1285
1286      buf[0] = sbit->red;
1287      buf[1] = sbit->green;
1288      buf[2] = sbit->blue;
1289      size = 3;
1290   }
1291
1292   else
1293   {
1294      if (sbit->gray == 0 || sbit->gray > png_ptr->usr_bit_depth)
1295      {
1296         png_warning(png_ptr, "Invalid sBIT depth specified");
1297         return;
1298      }
1299
1300      buf[0] = sbit->gray;
1301      size = 1;
1302   }
1303
1304   if (color_type & PNG_COLOR_MASK_ALPHA)
1305   {
1306      if (sbit->alpha == 0 || sbit->alpha > png_ptr->usr_bit_depth)
1307      {
1308         png_warning(png_ptr, "Invalid sBIT depth specified");
1309         return;
1310      }
1311
1312      buf[size++] = sbit->alpha;
1313   }
1314
1315   png_write_complete_chunk(png_ptr, png_sBIT, buf, size);
1316}
1317#endif
1318
1319#ifdef PNG_WRITE_cHRM_SUPPORTED
1320/* Write the cHRM chunk */
1321void /* PRIVATE */
1322png_write_cHRM_fixed(png_structp png_ptr, png_fixed_point white_x,
1323    png_fixed_point white_y, png_fixed_point red_x, png_fixed_point red_y,
1324    png_fixed_point green_x, png_fixed_point green_y, png_fixed_point blue_x,
1325    png_fixed_point blue_y)
1326{
1327   png_byte buf[32];
1328
1329   png_debug(1, "in png_write_cHRM");
1330
1331   /* Each value is saved in 1/100,000ths */
1332#ifdef PNG_CHECK_cHRM_SUPPORTED
1333   if (png_check_cHRM_fixed(png_ptr, white_x, white_y, red_x, red_y,
1334       green_x, green_y, blue_x, blue_y))
1335#endif
1336   {
1337      png_save_uint_32(buf, (png_uint_32)white_x);
1338      png_save_uint_32(buf + 4, (png_uint_32)white_y);
1339
1340      png_save_uint_32(buf + 8, (png_uint_32)red_x);
1341      png_save_uint_32(buf + 12, (png_uint_32)red_y);
1342
1343      png_save_uint_32(buf + 16, (png_uint_32)green_x);
1344      png_save_uint_32(buf + 20, (png_uint_32)green_y);
1345
1346      png_save_uint_32(buf + 24, (png_uint_32)blue_x);
1347      png_save_uint_32(buf + 28, (png_uint_32)blue_y);
1348
1349      png_write_complete_chunk(png_ptr, png_cHRM, buf, (png_size_t)32);
1350   }
1351}
1352#endif
1353
1354#ifdef PNG_WRITE_tRNS_SUPPORTED
1355/* Write the tRNS chunk */
1356void /* PRIVATE */
1357png_write_tRNS(png_structp png_ptr, png_const_bytep trans_alpha,
1358    png_const_color_16p tran, int num_trans, int color_type)
1359{
1360   png_byte buf[6];
1361
1362   png_debug(1, "in png_write_tRNS");
1363
1364   if (color_type == PNG_COLOR_TYPE_PALETTE)
1365   {
1366      if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette)
1367      {
1368         png_warning(png_ptr, "Invalid number of transparent colors specified");
1369         return;
1370      }
1371
1372      /* Write the chunk out as it is */
1373      png_write_complete_chunk(png_ptr, png_tRNS, trans_alpha, (png_size_t)num_trans);
1374   }
1375
1376   else if (color_type == PNG_COLOR_TYPE_GRAY)
1377   {
1378      /* One 16 bit value */
1379      if (tran->gray >= (1 << png_ptr->bit_depth))
1380      {
1381         png_warning(png_ptr,
1382             "Ignoring attempt to write tRNS chunk out-of-range for bit_depth");
1383
1384         return;
1385      }
1386
1387      png_save_uint_16(buf, tran->gray);
1388      png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)2);
1389   }
1390
1391   else if (color_type == PNG_COLOR_TYPE_RGB)
1392   {
1393      /* Three 16 bit values */
1394      png_save_uint_16(buf, tran->red);
1395      png_save_uint_16(buf + 2, tran->green);
1396      png_save_uint_16(buf + 4, tran->blue);
1397#ifdef PNG_WRITE_16BIT_SUPPORTED
1398      if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))
1399#else
1400      if (buf[0] | buf[2] | buf[4])
1401#endif
1402      {
1403         png_warning(png_ptr,
1404           "Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8");
1405         return;
1406      }
1407
1408      png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)6);
1409   }
1410
1411   else
1412   {
1413      png_warning(png_ptr, "Can't write tRNS with an alpha channel");
1414   }
1415}
1416#endif
1417
1418#ifdef PNG_WRITE_bKGD_SUPPORTED
1419/* Write the background chunk */
1420void /* PRIVATE */
1421png_write_bKGD(png_structp png_ptr, png_const_color_16p back, int color_type)
1422{
1423   png_byte buf[6];
1424
1425   png_debug(1, "in png_write_bKGD");
1426
1427   if (color_type == PNG_COLOR_TYPE_PALETTE)
1428   {
1429      if (
1430#ifdef PNG_MNG_FEATURES_SUPPORTED
1431          (png_ptr->num_palette ||
1432          (!(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE))) &&
1433#endif
1434         back->index >= png_ptr->num_palette)
1435      {
1436         png_warning(png_ptr, "Invalid background palette index");
1437         return;
1438      }
1439
1440      buf[0] = back->index;
1441      png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)1);
1442   }
1443
1444   else if (color_type & PNG_COLOR_MASK_COLOR)
1445   {
1446      png_save_uint_16(buf, back->red);
1447      png_save_uint_16(buf + 2, back->green);
1448      png_save_uint_16(buf + 4, back->blue);
1449#ifdef PNG_WRITE_16BIT_SUPPORTED
1450      if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))
1451#else
1452      if (buf[0] | buf[2] | buf[4])
1453#endif
1454      {
1455         png_warning(png_ptr,
1456             "Ignoring attempt to write 16-bit bKGD chunk when bit_depth is 8");
1457
1458         return;
1459      }
1460
1461      png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)6);
1462   }
1463
1464   else
1465   {
1466      if (back->gray >= (1 << png_ptr->bit_depth))
1467      {
1468         png_warning(png_ptr,
1469             "Ignoring attempt to write bKGD chunk out-of-range for bit_depth");
1470
1471         return;
1472      }
1473
1474      png_save_uint_16(buf, back->gray);
1475      png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)2);
1476   }
1477}
1478#endif
1479
1480#ifdef PNG_WRITE_hIST_SUPPORTED
1481/* Write the histogram */
1482void /* PRIVATE */
1483png_write_hIST(png_structp png_ptr, png_const_uint_16p hist, int num_hist)
1484{
1485   int i;
1486   png_byte buf[3];
1487
1488   png_debug(1, "in png_write_hIST");
1489
1490   if (num_hist > (int)png_ptr->num_palette)
1491   {
1492      png_debug2(3, "num_hist = %d, num_palette = %d", num_hist,
1493          png_ptr->num_palette);
1494
1495      png_warning(png_ptr, "Invalid number of histogram entries specified");
1496      return;
1497   }
1498
1499   png_write_chunk_header(png_ptr, png_hIST, (png_uint_32)(num_hist * 2));
1500
1501   for (i = 0; i < num_hist; i++)
1502   {
1503      png_save_uint_16(buf, hist[i]);
1504      png_write_chunk_data(png_ptr, buf, (png_size_t)2);
1505   }
1506
1507   png_write_chunk_end(png_ptr);
1508}
1509#endif
1510
1511#if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \
1512    defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
1513/* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification,
1514 * and if invalid, correct the keyword rather than discarding the entire
1515 * chunk.  The PNG 1.0 specification requires keywords 1-79 characters in
1516 * length, forbids leading or trailing whitespace, multiple internal spaces,
1517 * and the non-break space (0x80) from ISO 8859-1.  Returns keyword length.
1518 *
1519 * The new_key is allocated to hold the corrected keyword and must be freed
1520 * by the calling routine.  This avoids problems with trying to write to
1521 * static keywords without having to have duplicate copies of the strings.
1522 */
1523png_size_t /* PRIVATE */
1524png_check_keyword(png_structp png_ptr, png_const_charp key, png_charpp new_key)
1525{
1526   png_size_t key_len;
1527   png_const_charp ikp;
1528   png_charp kp, dp;
1529   int kflag;
1530   int kwarn=0;
1531
1532   png_debug(1, "in png_check_keyword");
1533
1534   *new_key = NULL;
1535
1536   if (key == NULL || (key_len = png_strlen(key)) == 0)
1537   {
1538      png_warning(png_ptr, "zero length keyword");
1539      return ((png_size_t)0);
1540   }
1541
1542   png_debug1(2, "Keyword to be checked is '%s'", key);
1543
1544   *new_key = (png_charp)png_malloc_warn(png_ptr, (png_uint_32)(key_len + 2));
1545
1546   if (*new_key == NULL)
1547   {
1548      png_warning(png_ptr, "Out of memory while procesing keyword");
1549      return ((png_size_t)0);
1550   }
1551
1552   /* Replace non-printing characters with a blank and print a warning */
1553   for (ikp = key, dp = *new_key; *ikp != '\0'; ikp++, dp++)
1554   {
1555      if ((png_byte)*ikp < 0x20 ||
1556         ((png_byte)*ikp > 0x7E && (png_byte)*ikp < 0xA1))
1557      {
1558         PNG_WARNING_PARAMETERS(p)
1559
1560         png_warning_parameter_unsigned(p, 1, PNG_NUMBER_FORMAT_02x,
1561            (png_byte)*ikp);
1562         png_formatted_warning(png_ptr, p, "invalid keyword character 0x@1");
1563         *dp = ' ';
1564      }
1565
1566      else
1567      {
1568         *dp = *ikp;
1569      }
1570   }
1571   *dp = '\0';
1572
1573   /* Remove any trailing white space. */
1574   kp = *new_key + key_len - 1;
1575   if (*kp == ' ')
1576   {
1577      png_warning(png_ptr, "trailing spaces removed from keyword");
1578
1579      while (*kp == ' ')
1580      {
1581         *(kp--) = '\0';
1582         key_len--;
1583      }
1584   }
1585
1586   /* Remove any leading white space. */
1587   kp = *new_key;
1588   if (*kp == ' ')
1589   {
1590      png_warning(png_ptr, "leading spaces removed from keyword");
1591
1592      while (*kp == ' ')
1593      {
1594         kp++;
1595         key_len--;
1596      }
1597   }
1598
1599   png_debug1(2, "Checking for multiple internal spaces in '%s'", kp);
1600
1601   /* Remove multiple internal spaces. */
1602   for (kflag = 0, dp = *new_key; *kp != '\0'; kp++)
1603   {
1604      if (*kp == ' ' && kflag == 0)
1605      {
1606         *(dp++) = *kp;
1607         kflag = 1;
1608      }
1609
1610      else if (*kp == ' ')
1611      {
1612         key_len--;
1613         kwarn = 1;
1614      }
1615
1616      else
1617      {
1618         *(dp++) = *kp;
1619         kflag = 0;
1620      }
1621   }
1622   *dp = '\0';
1623   if (kwarn)
1624      png_warning(png_ptr, "extra interior spaces removed from keyword");
1625
1626   if (key_len == 0)
1627   {
1628      png_free(png_ptr, *new_key);
1629      png_warning(png_ptr, "Zero length keyword");
1630   }
1631
1632   if (key_len > 79)
1633   {
1634      png_warning(png_ptr, "keyword length must be 1 - 79 characters");
1635      (*new_key)[79] = '\0';
1636      key_len = 79;
1637   }
1638
1639   return (key_len);
1640}
1641#endif
1642
1643#ifdef PNG_WRITE_tEXt_SUPPORTED
1644/* Write a tEXt chunk */
1645void /* PRIVATE */
1646png_write_tEXt(png_structp png_ptr, png_const_charp key, png_const_charp text,
1647    png_size_t text_len)
1648{
1649   png_size_t key_len;
1650   png_charp new_key;
1651
1652   png_debug(1, "in png_write_tEXt");
1653
1654   if ((key_len = png_check_keyword(png_ptr, key, &new_key))==0)
1655      return;
1656
1657   if (text == NULL || *text == '\0')
1658      text_len = 0;
1659
1660   else
1661      text_len = png_strlen(text);
1662
1663   /* Make sure we include the 0 after the key */
1664   png_write_chunk_header(png_ptr, png_tEXt,
1665       (png_uint_32)(key_len + text_len + 1));
1666   /*
1667    * We leave it to the application to meet PNG-1.0 requirements on the
1668    * contents of the text.  PNG-1.0 through PNG-1.2 discourage the use of
1669    * any non-Latin-1 characters except for NEWLINE.  ISO PNG will forbid them.
1670    * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1671    */
1672   png_write_chunk_data(png_ptr, (png_bytep)new_key,
1673       (png_size_t)(key_len + 1));
1674
1675   if (text_len)
1676      png_write_chunk_data(png_ptr, (png_const_bytep)text,
1677          (png_size_t)text_len);
1678
1679   png_write_chunk_end(png_ptr);
1680   png_free(png_ptr, new_key);
1681}
1682#endif
1683
1684#ifdef PNG_WRITE_zTXt_SUPPORTED
1685/* Write a compressed text chunk */
1686void /* PRIVATE */
1687png_write_zTXt(png_structp png_ptr, png_const_charp key, png_const_charp text,
1688    png_size_t text_len, int compression)
1689{
1690   png_size_t key_len;
1691   png_byte buf;
1692   png_charp new_key;
1693   compression_state comp;
1694
1695   png_debug(1, "in png_write_zTXt");
1696
1697   comp.num_output_ptr = 0;
1698   comp.max_output_ptr = 0;
1699   comp.output_ptr = NULL;
1700   comp.input = NULL;
1701   comp.input_len = 0;
1702
1703   if ((key_len = png_check_keyword(png_ptr, key, &new_key)) == 0)
1704   {
1705      png_free(png_ptr, new_key);
1706      return;
1707   }
1708
1709   if (text == NULL || *text == '\0' || compression==PNG_TEXT_COMPRESSION_NONE)
1710   {
1711      png_write_tEXt(png_ptr, new_key, text, (png_size_t)0);
1712      png_free(png_ptr, new_key);
1713      return;
1714   }
1715
1716   text_len = png_strlen(text);
1717
1718   /* Compute the compressed data; do it now for the length */
1719   text_len = png_text_compress(png_ptr, text, text_len, compression,
1720       &comp);
1721
1722   /* Write start of chunk */
1723   png_write_chunk_header(png_ptr, png_zTXt,
1724       (png_uint_32)(key_len+text_len + 2));
1725
1726   /* Write key */
1727   png_write_chunk_data(png_ptr, (png_bytep)new_key,
1728       (png_size_t)(key_len + 1));
1729
1730   png_free(png_ptr, new_key);
1731
1732   buf = (png_byte)compression;
1733
1734   /* Write compression */
1735   png_write_chunk_data(png_ptr, &buf, (png_size_t)1);
1736
1737   /* Write the compressed data */
1738   png_write_compressed_data_out(png_ptr, &comp, text_len);
1739
1740   /* Close the chunk */
1741   png_write_chunk_end(png_ptr);
1742}
1743#endif
1744
1745#ifdef PNG_WRITE_iTXt_SUPPORTED
1746/* Write an iTXt chunk */
1747void /* PRIVATE */
1748png_write_iTXt(png_structp png_ptr, int compression, png_const_charp key,
1749    png_const_charp lang, png_const_charp lang_key, png_const_charp text)
1750{
1751   png_size_t lang_len, key_len, lang_key_len, text_len;
1752   png_charp new_lang;
1753   png_charp new_key = NULL;
1754   png_byte cbuf[2];
1755   compression_state comp;
1756
1757   png_debug(1, "in png_write_iTXt");
1758
1759   comp.num_output_ptr = 0;
1760   comp.max_output_ptr = 0;
1761   comp.output_ptr = NULL;
1762   comp.input = NULL;
1763
1764   if ((key_len = png_check_keyword(png_ptr, key, &new_key)) == 0)
1765      return;
1766
1767   if ((lang_len = png_check_keyword(png_ptr, lang, &new_lang)) == 0)
1768   {
1769      png_warning(png_ptr, "Empty language field in iTXt chunk");
1770      new_lang = NULL;
1771      lang_len = 0;
1772   }
1773
1774   if (lang_key == NULL)
1775      lang_key_len = 0;
1776
1777   else
1778      lang_key_len = png_strlen(lang_key);
1779
1780   if (text == NULL)
1781      text_len = 0;
1782
1783   else
1784      text_len = png_strlen(text);
1785
1786   /* Compute the compressed data; do it now for the length */
1787   text_len = png_text_compress(png_ptr, text, text_len, compression - 2,
1788       &comp);
1789
1790
1791   /* Make sure we include the compression flag, the compression byte,
1792    * and the NULs after the key, lang, and lang_key parts
1793    */
1794
1795   png_write_chunk_header(png_ptr, png_iTXt, (png_uint_32)(
1796        5 /* comp byte, comp flag, terminators for key, lang and lang_key */
1797        + key_len
1798        + lang_len
1799        + lang_key_len
1800        + text_len));
1801
1802   /* We leave it to the application to meet PNG-1.0 requirements on the
1803    * contents of the text.  PNG-1.0 through PNG-1.2 discourage the use of
1804    * any non-Latin-1 characters except for NEWLINE.  ISO PNG will forbid them.
1805    * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1806    */
1807   png_write_chunk_data(png_ptr, (png_bytep)new_key, (png_size_t)(key_len + 1));
1808
1809   /* Set the compression flag */
1810   if (compression == PNG_ITXT_COMPRESSION_NONE ||
1811       compression == PNG_TEXT_COMPRESSION_NONE)
1812      cbuf[0] = 0;
1813
1814   else /* compression == PNG_ITXT_COMPRESSION_zTXt */
1815      cbuf[0] = 1;
1816
1817   /* Set the compression method */
1818   cbuf[1] = 0;
1819
1820   png_write_chunk_data(png_ptr, cbuf, (png_size_t)2);
1821
1822   cbuf[0] = 0;
1823   png_write_chunk_data(png_ptr, (new_lang ? (png_const_bytep)new_lang : cbuf),
1824       (png_size_t)(lang_len + 1));
1825
1826   png_write_chunk_data(png_ptr, (lang_key ? (png_const_bytep)lang_key : cbuf),
1827       (png_size_t)(lang_key_len + 1));
1828
1829   png_write_compressed_data_out(png_ptr, &comp, text_len);
1830
1831   png_write_chunk_end(png_ptr);
1832
1833   png_free(png_ptr, new_key);
1834   png_free(png_ptr, new_lang);
1835}
1836#endif
1837
1838#ifdef PNG_WRITE_oFFs_SUPPORTED
1839/* Write the oFFs chunk */
1840void /* PRIVATE */
1841png_write_oFFs(png_structp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
1842    int unit_type)
1843{
1844   png_byte buf[9];
1845
1846   png_debug(1, "in png_write_oFFs");
1847
1848   if (unit_type >= PNG_OFFSET_LAST)
1849      png_warning(png_ptr, "Unrecognized unit type for oFFs chunk");
1850
1851   png_save_int_32(buf, x_offset);
1852   png_save_int_32(buf + 4, y_offset);
1853   buf[8] = (png_byte)unit_type;
1854
1855   png_write_complete_chunk(png_ptr, png_oFFs, buf, (png_size_t)9);
1856}
1857#endif
1858#ifdef PNG_WRITE_pCAL_SUPPORTED
1859/* Write the pCAL chunk (described in the PNG extensions document) */
1860void /* PRIVATE */
1861png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
1862    png_int_32 X1, int type, int nparams, png_const_charp units,
1863    png_charpp params)
1864{
1865   png_size_t purpose_len, units_len, total_len;
1866   png_size_tp params_len;
1867   png_byte buf[10];
1868   png_charp new_purpose;
1869   int i;
1870
1871   png_debug1(1, "in png_write_pCAL (%d parameters)", nparams);
1872
1873   if (type >= PNG_EQUATION_LAST)
1874      png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");
1875
1876   purpose_len = png_check_keyword(png_ptr, purpose, &new_purpose) + 1;
1877   png_debug1(3, "pCAL purpose length = %d", (int)purpose_len);
1878   units_len = png_strlen(units) + (nparams == 0 ? 0 : 1);
1879   png_debug1(3, "pCAL units length = %d", (int)units_len);
1880   total_len = purpose_len + units_len + 10;
1881
1882   params_len = (png_size_tp)png_malloc(png_ptr,
1883       (png_alloc_size_t)(nparams * png_sizeof(png_size_t)));
1884
1885   /* Find the length of each parameter, making sure we don't count the
1886    * null terminator for the last parameter.
1887    */
1888   for (i = 0; i < nparams; i++)
1889   {
1890      params_len[i] = png_strlen(params[i]) + (i == nparams - 1 ? 0 : 1);
1891      png_debug2(3, "pCAL parameter %d length = %lu", i,
1892          (unsigned long)params_len[i]);
1893      total_len += params_len[i];
1894   }
1895
1896   png_debug1(3, "pCAL total length = %d", (int)total_len);
1897   png_write_chunk_header(png_ptr, png_pCAL, (png_uint_32)total_len);
1898   png_write_chunk_data(png_ptr, (png_const_bytep)new_purpose, purpose_len);
1899   png_save_int_32(buf, X0);
1900   png_save_int_32(buf + 4, X1);
1901   buf[8] = (png_byte)type;
1902   buf[9] = (png_byte)nparams;
1903   png_write_chunk_data(png_ptr, buf, (png_size_t)10);
1904   png_write_chunk_data(png_ptr, (png_const_bytep)units, (png_size_t)units_len);
1905
1906   png_free(png_ptr, new_purpose);
1907
1908   for (i = 0; i < nparams; i++)
1909   {
1910      png_write_chunk_data(png_ptr, (png_const_bytep)params[i], params_len[i]);
1911   }
1912
1913   png_free(png_ptr, params_len);
1914   png_write_chunk_end(png_ptr);
1915}
1916#endif
1917
1918#ifdef PNG_WRITE_sCAL_SUPPORTED
1919/* Write the sCAL chunk */
1920void /* PRIVATE */
1921png_write_sCAL_s(png_structp png_ptr, int unit, png_const_charp width,
1922    png_const_charp height)
1923{
1924   png_byte buf[64];
1925   png_size_t wlen, hlen, total_len;
1926
1927   png_debug(1, "in png_write_sCAL_s");
1928
1929   wlen = png_strlen(width);
1930   hlen = png_strlen(height);
1931   total_len = wlen + hlen + 2;
1932
1933   if (total_len > 64)
1934   {
1935      png_warning(png_ptr, "Can't write sCAL (buffer too small)");
1936      return;
1937   }
1938
1939   buf[0] = (png_byte)unit;
1940   png_memcpy(buf + 1, width, wlen + 1);      /* Append the '\0' here */
1941   png_memcpy(buf + wlen + 2, height, hlen);  /* Do NOT append the '\0' here */
1942
1943   png_debug1(3, "sCAL total length = %u", (unsigned int)total_len);
1944   png_write_complete_chunk(png_ptr, png_sCAL, buf, total_len);
1945}
1946#endif
1947
1948#ifdef PNG_WRITE_pHYs_SUPPORTED
1949/* Write the pHYs chunk */
1950void /* PRIVATE */
1951png_write_pHYs(png_structp png_ptr, png_uint_32 x_pixels_per_unit,
1952    png_uint_32 y_pixels_per_unit,
1953    int unit_type)
1954{
1955   png_byte buf[9];
1956
1957   png_debug(1, "in png_write_pHYs");
1958
1959   if (unit_type >= PNG_RESOLUTION_LAST)
1960      png_warning(png_ptr, "Unrecognized unit type for pHYs chunk");
1961
1962   png_save_uint_32(buf, x_pixels_per_unit);
1963   png_save_uint_32(buf + 4, y_pixels_per_unit);
1964   buf[8] = (png_byte)unit_type;
1965
1966   png_write_complete_chunk(png_ptr, png_pHYs, buf, (png_size_t)9);
1967}
1968#endif
1969
1970#ifdef PNG_WRITE_tIME_SUPPORTED
1971/* Write the tIME chunk.  Use either png_convert_from_struct_tm()
1972 * or png_convert_from_time_t(), or fill in the structure yourself.
1973 */
1974void /* PRIVATE */
1975png_write_tIME(png_structp png_ptr, png_const_timep mod_time)
1976{
1977   png_byte buf[7];
1978
1979   png_debug(1, "in png_write_tIME");
1980
1981   if (mod_time->month  > 12 || mod_time->month  < 1 ||
1982       mod_time->day    > 31 || mod_time->day    < 1 ||
1983       mod_time->hour   > 23 || mod_time->second > 60)
1984   {
1985      png_warning(png_ptr, "Invalid time specified for tIME chunk");
1986      return;
1987   }
1988
1989   png_save_uint_16(buf, mod_time->year);
1990   buf[2] = mod_time->month;
1991   buf[3] = mod_time->day;
1992   buf[4] = mod_time->hour;
1993   buf[5] = mod_time->minute;
1994   buf[6] = mod_time->second;
1995
1996   png_write_complete_chunk(png_ptr, png_tIME, buf, (png_size_t)7);
1997}
1998#endif
1999
2000/* Initializes the row writing capability of libpng */
2001void /* PRIVATE */
2002png_write_start_row(png_structp png_ptr)
2003{
2004#ifdef PNG_WRITE_INTERLACING_SUPPORTED
2005   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
2006
2007   /* Start of interlace block */
2008   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
2009
2010   /* Offset to next interlace block */
2011   static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
2012
2013   /* Start of interlace block in the y direction */
2014   static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
2015
2016   /* Offset to next interlace block in the y direction */
2017   static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
2018#endif
2019
2020   png_alloc_size_t buf_size;
2021   int usr_pixel_depth;
2022
2023   png_debug(1, "in png_write_start_row");
2024
2025   usr_pixel_depth = png_ptr->usr_channels * png_ptr->usr_bit_depth;
2026   buf_size = PNG_ROWBYTES(usr_pixel_depth, png_ptr->width) + 1;
2027
2028   /* 1.5.6: added to allow checking in the row write code. */
2029   png_ptr->transformed_pixel_depth = png_ptr->pixel_depth;
2030   png_ptr->maximum_pixel_depth = (png_byte)usr_pixel_depth;
2031
2032   /* Set up row buffer */
2033   png_ptr->row_buf = (png_bytep)png_malloc(png_ptr, buf_size);
2034
2035   png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE;
2036
2037#ifdef PNG_WRITE_FILTER_SUPPORTED
2038   /* Set up filtering buffer, if using this filter */
2039   if (png_ptr->do_filter & PNG_FILTER_SUB)
2040   {
2041      png_ptr->sub_row = (png_bytep)png_malloc(png_ptr, png_ptr->rowbytes + 1);
2042
2043      png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
2044   }
2045
2046   /* We only need to keep the previous row if we are using one of these. */
2047   if (png_ptr->do_filter & (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH))
2048   {
2049      /* Set up previous row buffer */
2050      png_ptr->prev_row = (png_bytep)png_calloc(png_ptr, buf_size);
2051
2052      if (png_ptr->do_filter & PNG_FILTER_UP)
2053      {
2054         png_ptr->up_row = (png_bytep)png_malloc(png_ptr,
2055            png_ptr->rowbytes + 1);
2056
2057         png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;
2058      }
2059
2060      if (png_ptr->do_filter & PNG_FILTER_AVG)
2061      {
2062         png_ptr->avg_row = (png_bytep)png_malloc(png_ptr,
2063             png_ptr->rowbytes + 1);
2064
2065         png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;
2066      }
2067
2068      if (png_ptr->do_filter & PNG_FILTER_PAETH)
2069      {
2070         png_ptr->paeth_row = (png_bytep)png_malloc(png_ptr,
2071             png_ptr->rowbytes + 1);
2072
2073         png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
2074      }
2075   }
2076#endif /* PNG_WRITE_FILTER_SUPPORTED */
2077
2078#ifdef PNG_WRITE_INTERLACING_SUPPORTED
2079   /* If interlaced, we need to set up width and height of pass */
2080   if (png_ptr->interlaced)
2081   {
2082      if (!(png_ptr->transformations & PNG_INTERLACE))
2083      {
2084         png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
2085             png_pass_ystart[0]) / png_pass_yinc[0];
2086
2087         png_ptr->usr_width = (png_ptr->width + png_pass_inc[0] - 1 -
2088             png_pass_start[0]) / png_pass_inc[0];
2089      }
2090
2091      else
2092      {
2093         png_ptr->num_rows = png_ptr->height;
2094         png_ptr->usr_width = png_ptr->width;
2095      }
2096   }
2097
2098   else
2099#endif
2100   {
2101      png_ptr->num_rows = png_ptr->height;
2102      png_ptr->usr_width = png_ptr->width;
2103   }
2104
2105   png_zlib_claim(png_ptr, PNG_ZLIB_FOR_IDAT);
2106   png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
2107   png_ptr->zstream.next_out = png_ptr->zbuf;
2108}
2109
2110/* Internal use only.  Called when finished processing a row of data. */
2111void /* PRIVATE */
2112png_write_finish_row(png_structp png_ptr)
2113{
2114#ifdef PNG_WRITE_INTERLACING_SUPPORTED
2115   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
2116
2117   /* Start of interlace block */
2118   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
2119
2120   /* Offset to next interlace block */
2121   static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
2122
2123   /* Start of interlace block in the y direction */
2124   static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
2125
2126   /* Offset to next interlace block in the y direction */
2127   static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
2128#endif
2129
2130   int ret;
2131
2132   png_debug(1, "in png_write_finish_row");
2133
2134   /* Next row */
2135   png_ptr->row_number++;
2136
2137   /* See if we are done */
2138   if (png_ptr->row_number < png_ptr->num_rows)
2139      return;
2140
2141#ifdef PNG_WRITE_INTERLACING_SUPPORTED
2142   /* If interlaced, go to next pass */
2143   if (png_ptr->interlaced)
2144   {
2145      png_ptr->row_number = 0;
2146      if (png_ptr->transformations & PNG_INTERLACE)
2147      {
2148         png_ptr->pass++;
2149      }
2150
2151      else
2152      {
2153         /* Loop until we find a non-zero width or height pass */
2154         do
2155         {
2156            png_ptr->pass++;
2157
2158            if (png_ptr->pass >= 7)
2159               break;
2160
2161            png_ptr->usr_width = (png_ptr->width +
2162                png_pass_inc[png_ptr->pass] - 1 -
2163                png_pass_start[png_ptr->pass]) /
2164                png_pass_inc[png_ptr->pass];
2165
2166            png_ptr->num_rows = (png_ptr->height +
2167                png_pass_yinc[png_ptr->pass] - 1 -
2168                png_pass_ystart[png_ptr->pass]) /
2169                png_pass_yinc[png_ptr->pass];
2170
2171            if (png_ptr->transformations & PNG_INTERLACE)
2172               break;
2173
2174         } while (png_ptr->usr_width == 0 || png_ptr->num_rows == 0);
2175
2176      }
2177
2178      /* Reset the row above the image for the next pass */
2179      if (png_ptr->pass < 7)
2180      {
2181         if (png_ptr->prev_row != NULL)
2182            png_memset(png_ptr->prev_row, 0,
2183                (png_size_t)(PNG_ROWBYTES(png_ptr->usr_channels*
2184                png_ptr->usr_bit_depth, png_ptr->width)) + 1);
2185
2186         return;
2187      }
2188   }
2189#endif
2190
2191   /* If we get here, we've just written the last row, so we need
2192      to flush the compressor */
2193   do
2194   {
2195      /* Tell the compressor we are done */
2196      ret = deflate(&png_ptr->zstream, Z_FINISH);
2197
2198      /* Check for an error */
2199      if (ret == Z_OK)
2200      {
2201         /* Check to see if we need more room */
2202         if (!(png_ptr->zstream.avail_out))
2203         {
2204            png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
2205            png_ptr->zstream.next_out = png_ptr->zbuf;
2206            png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
2207         }
2208      }
2209
2210      else if (ret != Z_STREAM_END)
2211      {
2212         if (png_ptr->zstream.msg != NULL)
2213            png_error(png_ptr, png_ptr->zstream.msg);
2214
2215         else
2216            png_error(png_ptr, "zlib error");
2217      }
2218   } while (ret != Z_STREAM_END);
2219
2220   /* Write any extra space */
2221   if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
2222   {
2223      png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size -
2224          png_ptr->zstream.avail_out);
2225   }
2226
2227   png_zlib_release(png_ptr);
2228   png_ptr->zstream.data_type = Z_BINARY;
2229}
2230
2231#ifdef PNG_WRITE_INTERLACING_SUPPORTED
2232/* Pick out the correct pixels for the interlace pass.
2233 * The basic idea here is to go through the row with a source
2234 * pointer and a destination pointer (sp and dp), and copy the
2235 * correct pixels for the pass.  As the row gets compacted,
2236 * sp will always be >= dp, so we should never overwrite anything.
2237 * See the default: case for the easiest code to understand.
2238 */
2239void /* PRIVATE */
2240png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
2241{
2242   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
2243
2244   /* Start of interlace block */
2245   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
2246
2247   /* Offset to next interlace block */
2248   static PNG_CONST png_byte  png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
2249
2250   png_debug(1, "in png_do_write_interlace");
2251
2252   /* We don't have to do anything on the last pass (6) */
2253   if (pass < 6)
2254   {
2255      /* Each pixel depth is handled separately */
2256      switch (row_info->pixel_depth)
2257      {
2258         case 1:
2259         {
2260            png_bytep sp;
2261            png_bytep dp;
2262            int shift;
2263            int d;
2264            int value;
2265            png_uint_32 i;
2266            png_uint_32 row_width = row_info->width;
2267
2268            dp = row;
2269            d = 0;
2270            shift = 7;
2271
2272            for (i = png_pass_start[pass]; i < row_width;
2273               i += png_pass_inc[pass])
2274            {
2275               sp = row + (png_size_t)(i >> 3);
2276               value = (int)(*sp >> (7 - (int)(i & 0x07))) & 0x01;
2277               d |= (value << shift);
2278
2279               if (shift == 0)
2280               {
2281                  shift = 7;
2282                  *dp++ = (png_byte)d;
2283                  d = 0;
2284               }
2285
2286               else
2287                  shift--;
2288
2289            }
2290            if (shift != 7)
2291               *dp = (png_byte)d;
2292
2293            break;
2294         }
2295
2296         case 2:
2297         {
2298            png_bytep sp;
2299            png_bytep dp;
2300            int shift;
2301            int d;
2302            int value;
2303            png_uint_32 i;
2304            png_uint_32 row_width = row_info->width;
2305
2306            dp = row;
2307            shift = 6;
2308            d = 0;
2309
2310            for (i = png_pass_start[pass]; i < row_width;
2311               i += png_pass_inc[pass])
2312            {
2313               sp = row + (png_size_t)(i >> 2);
2314               value = (*sp >> ((3 - (int)(i & 0x03)) << 1)) & 0x03;
2315               d |= (value << shift);
2316
2317               if (shift == 0)
2318               {
2319                  shift = 6;
2320                  *dp++ = (png_byte)d;
2321                  d = 0;
2322               }
2323
2324               else
2325                  shift -= 2;
2326            }
2327            if (shift != 6)
2328               *dp = (png_byte)d;
2329
2330            break;
2331         }
2332
2333         case 4:
2334         {
2335            png_bytep sp;
2336            png_bytep dp;
2337            int shift;
2338            int d;
2339            int value;
2340            png_uint_32 i;
2341            png_uint_32 row_width = row_info->width;
2342
2343            dp = row;
2344            shift = 4;
2345            d = 0;
2346            for (i = png_pass_start[pass]; i < row_width;
2347                i += png_pass_inc[pass])
2348            {
2349               sp = row + (png_size_t)(i >> 1);
2350               value = (*sp >> ((1 - (int)(i & 0x01)) << 2)) & 0x0f;
2351               d |= (value << shift);
2352
2353               if (shift == 0)
2354               {
2355                  shift = 4;
2356                  *dp++ = (png_byte)d;
2357                  d = 0;
2358               }
2359
2360               else
2361                  shift -= 4;
2362            }
2363            if (shift != 4)
2364               *dp = (png_byte)d;
2365
2366            break;
2367         }
2368
2369         default:
2370         {
2371            png_bytep sp;
2372            png_bytep dp;
2373            png_uint_32 i;
2374            png_uint_32 row_width = row_info->width;
2375            png_size_t pixel_bytes;
2376
2377            /* Start at the beginning */
2378            dp = row;
2379
2380            /* Find out how many bytes each pixel takes up */
2381            pixel_bytes = (row_info->pixel_depth >> 3);
2382
2383            /* Loop through the row, only looking at the pixels that matter */
2384            for (i = png_pass_start[pass]; i < row_width;
2385               i += png_pass_inc[pass])
2386            {
2387               /* Find out where the original pixel is */
2388               sp = row + (png_size_t)i * pixel_bytes;
2389
2390               /* Move the pixel */
2391               if (dp != sp)
2392                  png_memcpy(dp, sp, pixel_bytes);
2393
2394               /* Next pixel */
2395               dp += pixel_bytes;
2396            }
2397            break;
2398         }
2399      }
2400      /* Set new row width */
2401      row_info->width = (row_info->width +
2402          png_pass_inc[pass] - 1 -
2403          png_pass_start[pass]) /
2404          png_pass_inc[pass];
2405
2406      row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
2407          row_info->width);
2408   }
2409}
2410#endif
2411
2412/* This filters the row, chooses which filter to use, if it has not already
2413 * been specified by the application, and then writes the row out with the
2414 * chosen filter.
2415 */
2416static void png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row,
2417   png_size_t row_bytes);
2418
2419#define PNG_MAXSUM (((png_uint_32)(-1)) >> 1)
2420#define PNG_HISHIFT 10
2421#define PNG_LOMASK ((png_uint_32)0xffffL)
2422#define PNG_HIMASK ((png_uint_32)(~PNG_LOMASK >> PNG_HISHIFT))
2423void /* PRIVATE */
2424png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
2425{
2426   png_bytep best_row;
2427#ifdef PNG_WRITE_FILTER_SUPPORTED
2428   png_bytep prev_row, row_buf;
2429   png_uint_32 mins, bpp;
2430   png_byte filter_to_do = png_ptr->do_filter;
2431   png_size_t row_bytes = row_info->rowbytes;
2432#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2433   int num_p_filters = png_ptr->num_prev_filters;
2434#endif
2435
2436   png_debug(1, "in png_write_find_filter");
2437
2438#ifndef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2439  if (png_ptr->row_number == 0 && filter_to_do == PNG_ALL_FILTERS)
2440  {
2441     /* These will never be selected so we need not test them. */
2442     filter_to_do &= ~(PNG_FILTER_UP | PNG_FILTER_PAETH);
2443  }
2444#endif
2445
2446   /* Find out how many bytes offset each pixel is */
2447   bpp = (row_info->pixel_depth + 7) >> 3;
2448
2449   prev_row = png_ptr->prev_row;
2450#endif
2451   best_row = png_ptr->row_buf;
2452#ifdef PNG_WRITE_FILTER_SUPPORTED
2453   row_buf = best_row;
2454   mins = PNG_MAXSUM;
2455
2456   /* The prediction method we use is to find which method provides the
2457    * smallest value when summing the absolute values of the distances
2458    * from zero, using anything >= 128 as negative numbers.  This is known
2459    * as the "minimum sum of absolute differences" heuristic.  Other
2460    * heuristics are the "weighted minimum sum of absolute differences"
2461    * (experimental and can in theory improve compression), and the "zlib
2462    * predictive" method (not implemented yet), which does test compressions
2463    * of lines using different filter methods, and then chooses the
2464    * (series of) filter(s) that give minimum compressed data size (VERY
2465    * computationally expensive).
2466    *
2467    * GRR 980525:  consider also
2468    *
2469    *   (1) minimum sum of absolute differences from running average (i.e.,
2470    *       keep running sum of non-absolute differences & count of bytes)
2471    *       [track dispersion, too?  restart average if dispersion too large?]
2472    *
2473    *  (1b) minimum sum of absolute differences from sliding average, probably
2474    *       with window size <= deflate window (usually 32K)
2475    *
2476    *   (2) minimum sum of squared differences from zero or running average
2477    *       (i.e., ~ root-mean-square approach)
2478    */
2479
2480
2481   /* We don't need to test the 'no filter' case if this is the only filter
2482    * that has been chosen, as it doesn't actually do anything to the data.
2483    */
2484   if ((filter_to_do & PNG_FILTER_NONE) && filter_to_do != PNG_FILTER_NONE)
2485   {
2486      png_bytep rp;
2487      png_uint_32 sum = 0;
2488      png_size_t i;
2489      int v;
2490
2491      for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
2492      {
2493         v = *rp;
2494         sum += (v < 128) ? v : 256 - v;
2495      }
2496
2497#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2498      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2499      {
2500         png_uint_32 sumhi, sumlo;
2501         int j;
2502         sumlo = sum & PNG_LOMASK;
2503         sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; /* Gives us some footroom */
2504
2505         /* Reduce the sum if we match any of the previous rows */
2506         for (j = 0; j < num_p_filters; j++)
2507         {
2508            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
2509            {
2510               sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2511                   PNG_WEIGHT_SHIFT;
2512
2513               sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2514                   PNG_WEIGHT_SHIFT;
2515            }
2516         }
2517
2518         /* Factor in the cost of this filter (this is here for completeness,
2519          * but it makes no sense to have a "cost" for the NONE filter, as
2520          * it has the minimum possible computational cost - none).
2521          */
2522         sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
2523             PNG_COST_SHIFT;
2524
2525         sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
2526             PNG_COST_SHIFT;
2527
2528         if (sumhi > PNG_HIMASK)
2529            sum = PNG_MAXSUM;
2530
2531         else
2532            sum = (sumhi << PNG_HISHIFT) + sumlo;
2533      }
2534#endif
2535      mins = sum;
2536   }
2537
2538   /* Sub filter */
2539   if (filter_to_do == PNG_FILTER_SUB)
2540   /* It's the only filter so no testing is needed */
2541   {
2542      png_bytep rp, lp, dp;
2543      png_size_t i;
2544
2545      for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
2546           i++, rp++, dp++)
2547      {
2548         *dp = *rp;
2549      }
2550
2551      for (lp = row_buf + 1; i < row_bytes;
2552         i++, rp++, lp++, dp++)
2553      {
2554         *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
2555      }
2556
2557      best_row = png_ptr->sub_row;
2558   }
2559
2560   else if (filter_to_do & PNG_FILTER_SUB)
2561   {
2562      png_bytep rp, dp, lp;
2563      png_uint_32 sum = 0, lmins = mins;
2564      png_size_t i;
2565      int v;
2566
2567#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2568      /* We temporarily increase the "minimum sum" by the factor we
2569       * would reduce the sum of this filter, so that we can do the
2570       * early exit comparison without scaling the sum each time.
2571       */
2572      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2573      {
2574         int j;
2575         png_uint_32 lmhi, lmlo;
2576         lmlo = lmins & PNG_LOMASK;
2577         lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2578
2579         for (j = 0; j < num_p_filters; j++)
2580         {
2581            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
2582            {
2583               lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2584                   PNG_WEIGHT_SHIFT;
2585
2586               lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2587                   PNG_WEIGHT_SHIFT;
2588            }
2589         }
2590
2591         lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2592             PNG_COST_SHIFT;
2593
2594         lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2595             PNG_COST_SHIFT;
2596
2597         if (lmhi > PNG_HIMASK)
2598            lmins = PNG_MAXSUM;
2599
2600         else
2601            lmins = (lmhi << PNG_HISHIFT) + lmlo;
2602      }
2603#endif
2604
2605      for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
2606           i++, rp++, dp++)
2607      {
2608         v = *dp = *rp;
2609
2610         sum += (v < 128) ? v : 256 - v;
2611      }
2612
2613      for (lp = row_buf + 1; i < row_bytes;
2614         i++, rp++, lp++, dp++)
2615      {
2616         v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
2617
2618         sum += (v < 128) ? v : 256 - v;
2619
2620         if (sum > lmins)  /* We are already worse, don't continue. */
2621            break;
2622      }
2623
2624#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2625      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2626      {
2627         int j;
2628         png_uint_32 sumhi, sumlo;
2629         sumlo = sum & PNG_LOMASK;
2630         sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2631
2632         for (j = 0; j < num_p_filters; j++)
2633         {
2634            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
2635            {
2636               sumlo = (sumlo * png_ptr->inv_filter_weights[j]) >>
2637                   PNG_WEIGHT_SHIFT;
2638
2639               sumhi = (sumhi * png_ptr->inv_filter_weights[j]) >>
2640                   PNG_WEIGHT_SHIFT;
2641            }
2642         }
2643
2644         sumlo = (sumlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2645             PNG_COST_SHIFT;
2646
2647         sumhi = (sumhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2648             PNG_COST_SHIFT;
2649
2650         if (sumhi > PNG_HIMASK)
2651            sum = PNG_MAXSUM;
2652
2653         else
2654            sum = (sumhi << PNG_HISHIFT) + sumlo;
2655      }
2656#endif
2657
2658      if (sum < mins)
2659      {
2660         mins = sum;
2661         best_row = png_ptr->sub_row;
2662      }
2663   }
2664
2665   /* Up filter */
2666   if (filter_to_do == PNG_FILTER_UP)
2667   {
2668      png_bytep rp, dp, pp;
2669      png_size_t i;
2670
2671      for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
2672          pp = prev_row + 1; i < row_bytes;
2673          i++, rp++, pp++, dp++)
2674      {
2675         *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
2676      }
2677
2678      best_row = png_ptr->up_row;
2679   }
2680
2681   else if (filter_to_do & PNG_FILTER_UP)
2682   {
2683      png_bytep rp, dp, pp;
2684      png_uint_32 sum = 0, lmins = mins;
2685      png_size_t i;
2686      int v;
2687
2688
2689#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2690      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2691      {
2692         int j;
2693         png_uint_32 lmhi, lmlo;
2694         lmlo = lmins & PNG_LOMASK;
2695         lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2696
2697         for (j = 0; j < num_p_filters; j++)
2698         {
2699            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
2700            {
2701               lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2702                   PNG_WEIGHT_SHIFT;
2703
2704               lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2705                   PNG_WEIGHT_SHIFT;
2706            }
2707         }
2708
2709         lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
2710             PNG_COST_SHIFT;
2711
2712         lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
2713             PNG_COST_SHIFT;
2714
2715         if (lmhi > PNG_HIMASK)
2716            lmins = PNG_MAXSUM;
2717
2718         else
2719            lmins = (lmhi << PNG_HISHIFT) + lmlo;
2720      }
2721#endif
2722
2723      for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
2724          pp = prev_row + 1; i < row_bytes; i++)
2725      {
2726         v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2727
2728         sum += (v < 128) ? v : 256 - v;
2729
2730         if (sum > lmins)  /* We are already worse, don't continue. */
2731            break;
2732      }
2733
2734#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2735      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2736      {
2737         int j;
2738         png_uint_32 sumhi, sumlo;
2739         sumlo = sum & PNG_LOMASK;
2740         sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2741
2742         for (j = 0; j < num_p_filters; j++)
2743         {
2744            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
2745            {
2746               sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2747                   PNG_WEIGHT_SHIFT;
2748
2749               sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2750                   PNG_WEIGHT_SHIFT;
2751            }
2752         }
2753
2754         sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
2755             PNG_COST_SHIFT;
2756
2757         sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
2758             PNG_COST_SHIFT;
2759
2760         if (sumhi > PNG_HIMASK)
2761            sum = PNG_MAXSUM;
2762
2763         else
2764            sum = (sumhi << PNG_HISHIFT) + sumlo;
2765      }
2766#endif
2767
2768      if (sum < mins)
2769      {
2770         mins = sum;
2771         best_row = png_ptr->up_row;
2772      }
2773   }
2774
2775   /* Avg filter */
2776   if (filter_to_do == PNG_FILTER_AVG)
2777   {
2778      png_bytep rp, dp, pp, lp;
2779      png_uint_32 i;
2780
2781      for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
2782           pp = prev_row + 1; i < bpp; i++)
2783      {
2784         *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
2785      }
2786
2787      for (lp = row_buf + 1; i < row_bytes; i++)
2788      {
2789         *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
2790                 & 0xff);
2791      }
2792      best_row = png_ptr->avg_row;
2793   }
2794
2795   else if (filter_to_do & PNG_FILTER_AVG)
2796   {
2797      png_bytep rp, dp, pp, lp;
2798      png_uint_32 sum = 0, lmins = mins;
2799      png_size_t i;
2800      int v;
2801
2802#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2803      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2804      {
2805         int j;
2806         png_uint_32 lmhi, lmlo;
2807         lmlo = lmins & PNG_LOMASK;
2808         lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2809
2810         for (j = 0; j < num_p_filters; j++)
2811         {
2812            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_AVG)
2813            {
2814               lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2815                   PNG_WEIGHT_SHIFT;
2816
2817               lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2818                   PNG_WEIGHT_SHIFT;
2819            }
2820         }
2821
2822         lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
2823             PNG_COST_SHIFT;
2824
2825         lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
2826             PNG_COST_SHIFT;
2827
2828         if (lmhi > PNG_HIMASK)
2829            lmins = PNG_MAXSUM;
2830
2831         else
2832            lmins = (lmhi << PNG_HISHIFT) + lmlo;
2833      }
2834#endif
2835
2836      for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
2837           pp = prev_row + 1; i < bpp; i++)
2838      {
2839         v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
2840
2841         sum += (v < 128) ? v : 256 - v;
2842      }
2843
2844      for (lp = row_buf + 1; i < row_bytes; i++)
2845      {
2846         v = *dp++ =
2847             (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) & 0xff);
2848
2849         sum += (v < 128) ? v : 256 - v;
2850
2851         if (sum > lmins)  /* We are already worse, don't continue. */
2852            break;
2853      }
2854
2855#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2856      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2857      {
2858         int j;
2859         png_uint_32 sumhi, sumlo;
2860         sumlo = sum & PNG_LOMASK;
2861         sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2862
2863         for (j = 0; j < num_p_filters; j++)
2864         {
2865            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
2866            {
2867               sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2868                   PNG_WEIGHT_SHIFT;
2869
2870               sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2871                   PNG_WEIGHT_SHIFT;
2872            }
2873         }
2874
2875         sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
2876             PNG_COST_SHIFT;
2877
2878         sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
2879             PNG_COST_SHIFT;
2880
2881         if (sumhi > PNG_HIMASK)
2882            sum = PNG_MAXSUM;
2883
2884         else
2885            sum = (sumhi << PNG_HISHIFT) + sumlo;
2886      }
2887#endif
2888
2889      if (sum < mins)
2890      {
2891         mins = sum;
2892         best_row = png_ptr->avg_row;
2893      }
2894   }
2895
2896   /* Paeth filter */
2897   if (filter_to_do == PNG_FILTER_PAETH)
2898   {
2899      png_bytep rp, dp, pp, cp, lp;
2900      png_size_t i;
2901
2902      for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
2903          pp = prev_row + 1; i < bpp; i++)
2904      {
2905         *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2906      }
2907
2908      for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
2909      {
2910         int a, b, c, pa, pb, pc, p;
2911
2912         b = *pp++;
2913         c = *cp++;
2914         a = *lp++;
2915
2916         p = b - c;
2917         pc = a - c;
2918
2919#ifdef PNG_USE_ABS
2920         pa = abs(p);
2921         pb = abs(pc);
2922         pc = abs(p + pc);
2923#else
2924         pa = p < 0 ? -p : p;
2925         pb = pc < 0 ? -pc : pc;
2926         pc = (p + pc) < 0 ? -(p + pc) : p + pc;
2927#endif
2928
2929         p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
2930
2931         *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
2932      }
2933      best_row = png_ptr->paeth_row;
2934   }
2935
2936   else if (filter_to_do & PNG_FILTER_PAETH)
2937   {
2938      png_bytep rp, dp, pp, cp, lp;
2939      png_uint_32 sum = 0, lmins = mins;
2940      png_size_t i;
2941      int v;
2942
2943#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
2944      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2945      {
2946         int j;
2947         png_uint_32 lmhi, lmlo;
2948         lmlo = lmins & PNG_LOMASK;
2949         lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2950
2951         for (j = 0; j < num_p_filters; j++)
2952         {
2953            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
2954            {
2955               lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2956                   PNG_WEIGHT_SHIFT;
2957
2958               lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2959                   PNG_WEIGHT_SHIFT;
2960            }
2961         }
2962
2963         lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2964             PNG_COST_SHIFT;
2965
2966         lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2967             PNG_COST_SHIFT;
2968
2969         if (lmhi > PNG_HIMASK)
2970            lmins = PNG_MAXSUM;
2971
2972         else
2973            lmins = (lmhi << PNG_HISHIFT) + lmlo;
2974      }
2975#endif
2976
2977      for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
2978          pp = prev_row + 1; i < bpp; i++)
2979      {
2980         v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2981
2982         sum += (v < 128) ? v : 256 - v;
2983      }
2984
2985      for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
2986      {
2987         int a, b, c, pa, pb, pc, p;
2988
2989         b = *pp++;
2990         c = *cp++;
2991         a = *lp++;
2992
2993#ifndef PNG_SLOW_PAETH
2994         p = b - c;
2995         pc = a - c;
2996#ifdef PNG_USE_ABS
2997         pa = abs(p);
2998         pb = abs(pc);
2999         pc = abs(p + pc);
3000#else
3001         pa = p < 0 ? -p : p;
3002         pb = pc < 0 ? -pc : pc;
3003         pc = (p + pc) < 0 ? -(p + pc) : p + pc;
3004#endif
3005         p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
3006#else /* PNG_SLOW_PAETH */
3007         p = a + b - c;
3008         pa = abs(p - a);
3009         pb = abs(p - b);
3010         pc = abs(p - c);
3011
3012         if (pa <= pb && pa <= pc)
3013            p = a;
3014
3015         else if (pb <= pc)
3016            p = b;
3017
3018         else
3019            p = c;
3020#endif /* PNG_SLOW_PAETH */
3021
3022         v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
3023
3024         sum += (v < 128) ? v : 256 - v;
3025
3026         if (sum > lmins)  /* We are already worse, don't continue. */
3027            break;
3028      }
3029
3030#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
3031      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
3032      {
3033         int j;
3034         png_uint_32 sumhi, sumlo;
3035         sumlo = sum & PNG_LOMASK;
3036         sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
3037
3038         for (j = 0; j < num_p_filters; j++)
3039         {
3040            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
3041            {
3042               sumlo = (sumlo * png_ptr->filter_weights[j]) >>
3043                   PNG_WEIGHT_SHIFT;
3044
3045               sumhi = (sumhi * png_ptr->filter_weights[j]) >>
3046                   PNG_WEIGHT_SHIFT;
3047            }
3048         }
3049
3050         sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
3051             PNG_COST_SHIFT;
3052
3053         sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
3054             PNG_COST_SHIFT;
3055
3056         if (sumhi > PNG_HIMASK)
3057            sum = PNG_MAXSUM;
3058
3059         else
3060            sum = (sumhi << PNG_HISHIFT) + sumlo;
3061      }
3062#endif
3063
3064      if (sum < mins)
3065      {
3066         best_row = png_ptr->paeth_row;
3067      }
3068   }
3069#endif /* PNG_WRITE_FILTER_SUPPORTED */
3070
3071   /* Do the actual writing of the filtered row data from the chosen filter. */
3072   png_write_filtered_row(png_ptr, best_row, row_info->rowbytes+1);
3073
3074#ifdef PNG_WRITE_FILTER_SUPPORTED
3075#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
3076   /* Save the type of filter we picked this time for future calculations */
3077   if (png_ptr->num_prev_filters > 0)
3078   {
3079      int j;
3080
3081      for (j = 1; j < num_p_filters; j++)
3082      {
3083         png_ptr->prev_filters[j] = png_ptr->prev_filters[j - 1];
3084      }
3085
3086      png_ptr->prev_filters[j] = best_row[0];
3087   }
3088#endif
3089#endif /* PNG_WRITE_FILTER_SUPPORTED */
3090}
3091
3092
3093/* Do the actual writing of a previously filtered row. */
3094static void
3095png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row,
3096   png_size_t avail/*includes filter byte*/)
3097{
3098   png_debug(1, "in png_write_filtered_row");
3099
3100   png_debug1(2, "filter = %d", filtered_row[0]);
3101   /* Set up the zlib input buffer */
3102
3103   png_ptr->zstream.next_in = filtered_row;
3104   png_ptr->zstream.avail_in = 0;
3105   /* Repeat until we have compressed all the data */
3106   do
3107   {
3108      int ret; /* Return of zlib */
3109
3110      /* Record the number of bytes available - zlib supports at least 65535
3111       * bytes at one step, depending on the size of the zlib type 'uInt', the
3112       * maximum size zlib can write at once is ZLIB_IO_MAX (from pngpriv.h).
3113       * Use this because on 16 bit systems 'rowbytes' can be up to 65536 (i.e.
3114       * one more than 16 bits) and, in this case 'rowbytes+1' can overflow a
3115       * uInt.  ZLIB_IO_MAX can be safely reduced to cause zlib to be called
3116       * with smaller chunks of data.
3117       */
3118      if (png_ptr->zstream.avail_in == 0)
3119      {
3120         if (avail > ZLIB_IO_MAX)
3121         {
3122            png_ptr->zstream.avail_in  = ZLIB_IO_MAX;
3123            avail -= ZLIB_IO_MAX;
3124         }
3125
3126         else
3127         {
3128            /* So this will fit in the available uInt space: */
3129            png_ptr->zstream.avail_in = (uInt)avail;
3130            avail = 0;
3131         }
3132      }
3133
3134      /* Compress the data */
3135      ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
3136
3137      /* Check for compression errors */
3138      if (ret != Z_OK)
3139      {
3140         if (png_ptr->zstream.msg != NULL)
3141            png_error(png_ptr, png_ptr->zstream.msg);
3142
3143         else
3144            png_error(png_ptr, "zlib error");
3145      }
3146
3147      /* See if it is time to write another IDAT */
3148      if (!(png_ptr->zstream.avail_out))
3149      {
3150         /* Write the IDAT and reset the zlib output buffer */
3151         png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
3152      }
3153   /* Repeat until all data has been compressed */
3154   } while (avail > 0 || png_ptr->zstream.avail_in > 0);
3155
3156   /* Swap the current and previous rows */
3157   if (png_ptr->prev_row != NULL)
3158   {
3159      png_bytep tptr;
3160
3161      tptr = png_ptr->prev_row;
3162      png_ptr->prev_row = png_ptr->row_buf;
3163      png_ptr->row_buf = tptr;
3164   }
3165
3166   /* Finish row - updates counters and flushes zlib if last row */
3167   png_write_finish_row(png_ptr);
3168
3169#ifdef PNG_WRITE_FLUSH_SUPPORTED
3170   png_ptr->flush_rows++;
3171
3172   if (png_ptr->flush_dist > 0 &&
3173       png_ptr->flush_rows >= png_ptr->flush_dist)
3174   {
3175      png_write_flush(png_ptr);
3176   }
3177#endif
3178}
3179#endif /* PNG_WRITE_SUPPORTED */
3180