pngwutil.c revision 0640679f04398a7d06319d5c47b0f71bf82854a0
1
2/* pngwutil.c - utilities to write a PNG file
3 *
4 * Last changed in libpng 1.2.27 [April 29, 2008]
5 * For conditions of distribution and use, see copyright notice in png.h
6 * Copyright (c) 1998-2008 Glenn Randers-Pehrson
7 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
8 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
9 */
10
11#define PNG_INTERNAL
12#include "png.h"
13#ifdef PNG_WRITE_SUPPORTED
14
15/* Place a 32-bit number into a buffer in PNG byte order.  We work
16 * with unsigned numbers for convenience, although one supported
17 * ancillary chunk uses signed (two's complement) numbers.
18 */
19void PNGAPI
20png_save_uint_32(png_bytep buf, png_uint_32 i)
21{
22   buf[0] = (png_byte)((i >> 24) & 0xff);
23   buf[1] = (png_byte)((i >> 16) & 0xff);
24   buf[2] = (png_byte)((i >> 8) & 0xff);
25   buf[3] = (png_byte)(i & 0xff);
26}
27
28/* The png_save_int_32 function assumes integers are stored in two's
29 * complement format.  If this isn't the case, then this routine needs to
30 * be modified to write data in two's complement format.
31 */
32void PNGAPI
33png_save_int_32(png_bytep buf, png_int_32 i)
34{
35   buf[0] = (png_byte)((i >> 24) & 0xff);
36   buf[1] = (png_byte)((i >> 16) & 0xff);
37   buf[2] = (png_byte)((i >> 8) & 0xff);
38   buf[3] = (png_byte)(i & 0xff);
39}
40
41/* Place a 16-bit number into a buffer in PNG byte order.
42 * The parameter is declared unsigned int, not png_uint_16,
43 * just to avoid potential problems on pre-ANSI C compilers.
44 */
45void PNGAPI
46png_save_uint_16(png_bytep buf, unsigned int i)
47{
48   buf[0] = (png_byte)((i >> 8) & 0xff);
49   buf[1] = (png_byte)(i & 0xff);
50}
51
52/* Write a PNG chunk all at once.  The type is an array of ASCII characters
53 * representing the chunk name.  The array must be at least 4 bytes in
54 * length, and does not need to be null terminated.  To be safe, pass the
55 * pre-defined chunk names here, and if you need a new one, define it
56 * where the others are defined.  The length is the length of the data.
57 * All the data must be present.  If that is not possible, use the
58 * png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end()
59 * functions instead.
60 */
61void PNGAPI
62png_write_chunk(png_structp png_ptr, png_bytep chunk_name,
63   png_bytep data, png_size_t length)
64{
65   if(png_ptr == NULL) return;
66   png_write_chunk_start(png_ptr, chunk_name, (png_uint_32)length);
67   png_write_chunk_data(png_ptr, data, length);
68   png_write_chunk_end(png_ptr);
69}
70
71/* Write the start of a PNG chunk.  The type is the chunk type.
72 * The total_length is the sum of the lengths of all the data you will be
73 * passing in png_write_chunk_data().
74 */
75void PNGAPI
76png_write_chunk_start(png_structp png_ptr, png_bytep chunk_name,
77   png_uint_32 length)
78{
79   png_byte buf[4];
80   png_debug2(0, "Writing %s chunk (%lu bytes)\n", chunk_name, length);
81   if(png_ptr == NULL) return;
82
83   /* write the length */
84   png_save_uint_32(buf, length);
85   png_write_data(png_ptr, buf, (png_size_t)4);
86
87   /* write the chunk name */
88   png_write_data(png_ptr, chunk_name, (png_size_t)4);
89   /* reset the crc and run it over the chunk name */
90   png_reset_crc(png_ptr);
91   png_calculate_crc(png_ptr, chunk_name, (png_size_t)4);
92}
93
94/* Write the data of a PNG chunk started with png_write_chunk_start().
95 * Note that multiple calls to this function are allowed, and that the
96 * sum of the lengths from these calls *must* add up to the total_length
97 * given to png_write_chunk_start().
98 */
99void PNGAPI
100png_write_chunk_data(png_structp png_ptr, png_bytep data, png_size_t length)
101{
102   /* write the data, and run the CRC over it */
103   if(png_ptr == NULL) return;
104   if (data != NULL && length > 0)
105   {
106      png_calculate_crc(png_ptr, data, length);
107      png_write_data(png_ptr, data, length);
108   }
109}
110
111/* Finish a chunk started with png_write_chunk_start(). */
112void PNGAPI
113png_write_chunk_end(png_structp png_ptr)
114{
115   png_byte buf[4];
116
117   if(png_ptr == NULL) return;
118
119   /* write the crc */
120   png_save_uint_32(buf, png_ptr->crc);
121
122   png_write_data(png_ptr, buf, (png_size_t)4);
123}
124
125/* Simple function to write the signature.  If we have already written
126 * the magic bytes of the signature, or more likely, the PNG stream is
127 * being embedded into another stream and doesn't need its own signature,
128 * we should call png_set_sig_bytes() to tell libpng how many of the
129 * bytes have already been written.
130 */
131void /* PRIVATE */
132png_write_sig(png_structp png_ptr)
133{
134   png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
135   /* write the rest of the 8 byte signature */
136   png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes],
137      (png_size_t)8 - png_ptr->sig_bytes);
138   if(png_ptr->sig_bytes < 3)
139      png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
140}
141
142#if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_iCCP_SUPPORTED)
143/*
144 * This pair of functions encapsulates the operation of (a) compressing a
145 * text string, and (b) issuing it later as a series of chunk data writes.
146 * The compression_state structure is shared context for these functions
147 * set up by the caller in order to make the whole mess thread-safe.
148 */
149
150typedef struct
151{
152    char *input;   /* the uncompressed input data */
153    int input_len;   /* its length */
154    int num_output_ptr; /* number of output pointers used */
155    int max_output_ptr; /* size of output_ptr */
156    png_charpp output_ptr; /* array of pointers to output */
157} compression_state;
158
159/* compress given text into storage in the png_ptr structure */
160static int /* PRIVATE */
161png_text_compress(png_structp png_ptr,
162        png_charp text, png_size_t text_len, int compression,
163        compression_state *comp)
164{
165   int ret;
166
167   comp->num_output_ptr = 0;
168   comp->max_output_ptr = 0;
169   comp->output_ptr = NULL;
170   comp->input = NULL;
171   comp->input_len = 0;
172
173   /* we may just want to pass the text right through */
174   if (compression == PNG_TEXT_COMPRESSION_NONE)
175   {
176       comp->input = text;
177       comp->input_len = text_len;
178       return((int)text_len);
179   }
180
181   if (compression >= PNG_TEXT_COMPRESSION_LAST)
182   {
183#if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
184      char msg[50];
185      png_snprintf(msg, 50, "Unknown compression type %d", compression);
186      png_warning(png_ptr, msg);
187#else
188      png_warning(png_ptr, "Unknown compression type");
189#endif
190   }
191
192   /* We can't write the chunk until we find out how much data we have,
193    * which means we need to run the compressor first and save the
194    * output.  This shouldn't be a problem, as the vast majority of
195    * comments should be reasonable, but we will set up an array of
196    * malloc'd pointers to be sure.
197    *
198    * If we knew the application was well behaved, we could simplify this
199    * greatly by assuming we can always malloc an output buffer large
200    * enough to hold the compressed text ((1001 * text_len / 1000) + 12)
201    * and malloc this directly.  The only time this would be a bad idea is
202    * if we can't malloc more than 64K and we have 64K of random input
203    * data, or if the input string is incredibly large (although this
204    * wouldn't cause a failure, just a slowdown due to swapping).
205    */
206
207   /* set up the compression buffers */
208   png_ptr->zstream.avail_in = (uInt)text_len;
209   png_ptr->zstream.next_in = (Bytef *)text;
210   png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
211   png_ptr->zstream.next_out = (Bytef *)png_ptr->zbuf;
212
213   /* this is the same compression loop as in png_write_row() */
214   do
215   {
216      /* compress the data */
217      ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
218      if (ret != Z_OK)
219      {
220         /* error */
221         if (png_ptr->zstream.msg != NULL)
222            png_error(png_ptr, png_ptr->zstream.msg);
223         else
224            png_error(png_ptr, "zlib error");
225      }
226      /* check to see if we need more room */
227      if (!(png_ptr->zstream.avail_out))
228      {
229         /* make sure the output array has room */
230         if (comp->num_output_ptr >= comp->max_output_ptr)
231         {
232            int old_max;
233
234            old_max = comp->max_output_ptr;
235            comp->max_output_ptr = comp->num_output_ptr + 4;
236            if (comp->output_ptr != NULL)
237            {
238               png_charpp old_ptr;
239
240               old_ptr = comp->output_ptr;
241               comp->output_ptr = (png_charpp)png_malloc(png_ptr,
242                  (png_uint_32)(comp->max_output_ptr *
243                  png_sizeof (png_charpp)));
244               png_memcpy(comp->output_ptr, old_ptr, old_max
245                  * png_sizeof (png_charp));
246               png_free(png_ptr, old_ptr);
247            }
248            else
249               comp->output_ptr = (png_charpp)png_malloc(png_ptr,
250                  (png_uint_32)(comp->max_output_ptr *
251                  png_sizeof (png_charp)));
252         }
253
254         /* save the data */
255         comp->output_ptr[comp->num_output_ptr] = (png_charp)png_malloc(png_ptr,
256            (png_uint_32)png_ptr->zbuf_size);
257         png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
258            png_ptr->zbuf_size);
259         comp->num_output_ptr++;
260
261         /* and reset the buffer */
262         png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
263         png_ptr->zstream.next_out = png_ptr->zbuf;
264      }
265   /* continue until we don't have any more to compress */
266   } while (png_ptr->zstream.avail_in);
267
268   /* finish the compression */
269   do
270   {
271      /* tell zlib we are finished */
272      ret = deflate(&png_ptr->zstream, Z_FINISH);
273
274      if (ret == Z_OK)
275      {
276         /* check to see if we need more room */
277         if (!(png_ptr->zstream.avail_out))
278         {
279            /* check to make sure our output array has room */
280            if (comp->num_output_ptr >= comp->max_output_ptr)
281            {
282               int old_max;
283
284               old_max = comp->max_output_ptr;
285               comp->max_output_ptr = comp->num_output_ptr + 4;
286               if (comp->output_ptr != NULL)
287               {
288                  png_charpp old_ptr;
289
290                  old_ptr = comp->output_ptr;
291                  /* This could be optimized to realloc() */
292                  comp->output_ptr = (png_charpp)png_malloc(png_ptr,
293                     (png_uint_32)(comp->max_output_ptr *
294                     png_sizeof (png_charpp)));
295                  png_memcpy(comp->output_ptr, old_ptr,
296                     old_max * png_sizeof (png_charp));
297                  png_free(png_ptr, old_ptr);
298               }
299               else
300                  comp->output_ptr = (png_charpp)png_malloc(png_ptr,
301                     (png_uint_32)(comp->max_output_ptr *
302                     png_sizeof (png_charp)));
303            }
304
305            /* save off the data */
306            comp->output_ptr[comp->num_output_ptr] =
307               (png_charp)png_malloc(png_ptr, (png_uint_32)png_ptr->zbuf_size);
308            png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
309               png_ptr->zbuf_size);
310            comp->num_output_ptr++;
311
312            /* and reset the buffer pointers */
313            png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
314            png_ptr->zstream.next_out = png_ptr->zbuf;
315         }
316      }
317      else if (ret != Z_STREAM_END)
318      {
319         /* we got an error */
320         if (png_ptr->zstream.msg != NULL)
321            png_error(png_ptr, png_ptr->zstream.msg);
322         else
323            png_error(png_ptr, "zlib error");
324      }
325   } while (ret != Z_STREAM_END);
326
327   /* text length is number of buffers plus last buffer */
328   text_len = png_ptr->zbuf_size * comp->num_output_ptr;
329   if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
330      text_len += png_ptr->zbuf_size - (png_size_t)png_ptr->zstream.avail_out;
331
332   return((int)text_len);
333}
334
335/* ship the compressed text out via chunk writes */
336static void /* PRIVATE */
337png_write_compressed_data_out(png_structp png_ptr, compression_state *comp)
338{
339   int i;
340
341   /* handle the no-compression case */
342   if (comp->input)
343   {
344       png_write_chunk_data(png_ptr, (png_bytep)comp->input,
345                            (png_size_t)comp->input_len);
346       return;
347   }
348
349   /* write saved output buffers, if any */
350   for (i = 0; i < comp->num_output_ptr; i++)
351   {
352      png_write_chunk_data(png_ptr,(png_bytep)comp->output_ptr[i],
353         png_ptr->zbuf_size);
354      png_free(png_ptr, comp->output_ptr[i]);
355      comp->output_ptr[i]=NULL;
356   }
357   if (comp->max_output_ptr != 0)
358      png_free(png_ptr, comp->output_ptr);
359      comp->output_ptr=NULL;
360   /* write anything left in zbuf */
361   if (png_ptr->zstream.avail_out < (png_uint_32)png_ptr->zbuf_size)
362      png_write_chunk_data(png_ptr, png_ptr->zbuf,
363         png_ptr->zbuf_size - png_ptr->zstream.avail_out);
364
365   /* reset zlib for another zTXt/iTXt or image data */
366   deflateReset(&png_ptr->zstream);
367   png_ptr->zstream.data_type = Z_BINARY;
368}
369#endif
370
371/* Write the IHDR chunk, and update the png_struct with the necessary
372 * information.  Note that the rest of this code depends upon this
373 * information being correct.
374 */
375void /* PRIVATE */
376png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
377   int bit_depth, int color_type, int compression_type, int filter_type,
378   int interlace_type)
379{
380#ifdef PNG_USE_LOCAL_ARRAYS
381   PNG_IHDR;
382#endif
383   int ret;
384
385   png_byte buf[13]; /* buffer to store the IHDR info */
386
387   png_debug(1, "in png_write_IHDR\n");
388   /* Check that we have valid input data from the application info */
389   switch (color_type)
390   {
391      case PNG_COLOR_TYPE_GRAY:
392         switch (bit_depth)
393         {
394            case 1:
395            case 2:
396            case 4:
397            case 8:
398            case 16: png_ptr->channels = 1; break;
399            default: png_error(png_ptr,"Invalid bit depth for grayscale image");
400         }
401         break;
402      case PNG_COLOR_TYPE_RGB:
403         if (bit_depth != 8 && bit_depth != 16)
404            png_error(png_ptr, "Invalid bit depth for RGB image");
405         png_ptr->channels = 3;
406         break;
407      case PNG_COLOR_TYPE_PALETTE:
408         switch (bit_depth)
409         {
410            case 1:
411            case 2:
412            case 4:
413            case 8: png_ptr->channels = 1; break;
414            default: png_error(png_ptr, "Invalid bit depth for paletted image");
415         }
416         break;
417      case PNG_COLOR_TYPE_GRAY_ALPHA:
418         if (bit_depth != 8 && bit_depth != 16)
419            png_error(png_ptr, "Invalid bit depth for grayscale+alpha image");
420         png_ptr->channels = 2;
421         break;
422      case PNG_COLOR_TYPE_RGB_ALPHA:
423         if (bit_depth != 8 && bit_depth != 16)
424            png_error(png_ptr, "Invalid bit depth for RGBA image");
425         png_ptr->channels = 4;
426         break;
427      default:
428         png_error(png_ptr, "Invalid image color type specified");
429   }
430
431   if (compression_type != PNG_COMPRESSION_TYPE_BASE)
432   {
433      png_warning(png_ptr, "Invalid compression type specified");
434      compression_type = PNG_COMPRESSION_TYPE_BASE;
435   }
436
437   /* Write filter_method 64 (intrapixel differencing) only if
438    * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
439    * 2. Libpng did not write a PNG signature (this filter_method is only
440    *    used in PNG datastreams that are embedded in MNG datastreams) and
441    * 3. The application called png_permit_mng_features with a mask that
442    *    included PNG_FLAG_MNG_FILTER_64 and
443    * 4. The filter_method is 64 and
444    * 5. The color_type is RGB or RGBA
445    */
446   if (
447#if defined(PNG_MNG_FEATURES_SUPPORTED)
448      !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
449      ((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE) == 0) &&
450      (color_type == PNG_COLOR_TYPE_RGB ||
451       color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&
452      (filter_type == PNG_INTRAPIXEL_DIFFERENCING)) &&
453#endif
454      filter_type != PNG_FILTER_TYPE_BASE)
455   {
456      png_warning(png_ptr, "Invalid filter type specified");
457      filter_type = PNG_FILTER_TYPE_BASE;
458   }
459
460#ifdef PNG_WRITE_INTERLACING_SUPPORTED
461   if (interlace_type != PNG_INTERLACE_NONE &&
462      interlace_type != PNG_INTERLACE_ADAM7)
463   {
464      png_warning(png_ptr, "Invalid interlace type specified");
465      interlace_type = PNG_INTERLACE_ADAM7;
466   }
467#else
468   interlace_type=PNG_INTERLACE_NONE;
469#endif
470
471   /* save off the relevent information */
472   png_ptr->bit_depth = (png_byte)bit_depth;
473   png_ptr->color_type = (png_byte)color_type;
474   png_ptr->interlaced = (png_byte)interlace_type;
475#if defined(PNG_MNG_FEATURES_SUPPORTED)
476   png_ptr->filter_type = (png_byte)filter_type;
477#endif
478   png_ptr->compression_type = (png_byte)compression_type;
479   png_ptr->width = width;
480   png_ptr->height = height;
481
482   png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels);
483   png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width);
484   /* set the usr info, so any transformations can modify it */
485   png_ptr->usr_width = png_ptr->width;
486   png_ptr->usr_bit_depth = png_ptr->bit_depth;
487   png_ptr->usr_channels = png_ptr->channels;
488
489   /* pack the header information into the buffer */
490   png_save_uint_32(buf, width);
491   png_save_uint_32(buf + 4, height);
492   buf[8] = (png_byte)bit_depth;
493   buf[9] = (png_byte)color_type;
494   buf[10] = (png_byte)compression_type;
495   buf[11] = (png_byte)filter_type;
496   buf[12] = (png_byte)interlace_type;
497
498   /* write the chunk */
499   png_write_chunk(png_ptr, png_IHDR, buf, (png_size_t)13);
500
501   /* initialize zlib with PNG info */
502   png_ptr->zstream.zalloc = png_zalloc;
503   png_ptr->zstream.zfree = png_zfree;
504   png_ptr->zstream.opaque = (voidpf)png_ptr;
505   if (!(png_ptr->do_filter))
506   {
507      if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
508         png_ptr->bit_depth < 8)
509         png_ptr->do_filter = PNG_FILTER_NONE;
510      else
511         png_ptr->do_filter = PNG_ALL_FILTERS;
512   }
513   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY))
514   {
515      if (png_ptr->do_filter != PNG_FILTER_NONE)
516         png_ptr->zlib_strategy = Z_FILTERED;
517      else
518         png_ptr->zlib_strategy = Z_DEFAULT_STRATEGY;
519   }
520   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_LEVEL))
521      png_ptr->zlib_level = Z_DEFAULT_COMPRESSION;
522   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL))
523      png_ptr->zlib_mem_level = 8;
524   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS))
525      png_ptr->zlib_window_bits = 15;
526   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_METHOD))
527      png_ptr->zlib_method = 8;
528   ret = deflateInit2(&png_ptr->zstream, png_ptr->zlib_level,
529         png_ptr->zlib_method, png_ptr->zlib_window_bits,
530         png_ptr->zlib_mem_level, png_ptr->zlib_strategy);
531   if (ret != Z_OK)
532   {
533      if (ret == Z_VERSION_ERROR) png_error(png_ptr,
534          "zlib failed to initialize compressor -- version error");
535      if (ret == Z_STREAM_ERROR) png_error(png_ptr,
536           "zlib failed to initialize compressor -- stream error");
537      if (ret == Z_MEM_ERROR) png_error(png_ptr,
538           "zlib failed to initialize compressor -- mem error");
539      png_error(png_ptr, "zlib failed to initialize compressor");
540   }
541   png_ptr->zstream.next_out = png_ptr->zbuf;
542   png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
543   /* libpng is not interested in zstream.data_type */
544   /* set it to a predefined value, to avoid its evaluation inside zlib */
545   png_ptr->zstream.data_type = Z_BINARY;
546
547   png_ptr->mode = PNG_HAVE_IHDR;
548}
549
550/* write the palette.  We are careful not to trust png_color to be in the
551 * correct order for PNG, so people can redefine it to any convenient
552 * structure.
553 */
554void /* PRIVATE */
555png_write_PLTE(png_structp png_ptr, png_colorp palette, png_uint_32 num_pal)
556{
557#ifdef PNG_USE_LOCAL_ARRAYS
558   PNG_PLTE;
559#endif
560   png_uint_32 i;
561   png_colorp pal_ptr;
562   png_byte buf[3];
563
564   png_debug(1, "in png_write_PLTE\n");
565   if ((
566#if defined(PNG_MNG_FEATURES_SUPPORTED)
567        !(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) &&
568#endif
569        num_pal == 0) || num_pal > 256)
570   {
571     if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
572     {
573        png_error(png_ptr, "Invalid number of colors in palette");
574     }
575     else
576     {
577        png_warning(png_ptr, "Invalid number of colors in palette");
578        return;
579     }
580   }
581
582   if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))
583   {
584      png_warning(png_ptr,
585        "Ignoring request to write a PLTE chunk in grayscale PNG");
586      return;
587   }
588
589   png_ptr->num_palette = (png_uint_16)num_pal;
590   png_debug1(3, "num_palette = %d\n", png_ptr->num_palette);
591
592   png_write_chunk_start(png_ptr, png_PLTE, num_pal * 3);
593#ifndef PNG_NO_POINTER_INDEXING
594   for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++)
595   {
596      buf[0] = pal_ptr->red;
597      buf[1] = pal_ptr->green;
598      buf[2] = pal_ptr->blue;
599      png_write_chunk_data(png_ptr, buf, (png_size_t)3);
600   }
601#else
602   /* This is a little slower but some buggy compilers need to do this instead */
603   pal_ptr=palette;
604   for (i = 0; i < num_pal; i++)
605   {
606      buf[0] = pal_ptr[i].red;
607      buf[1] = pal_ptr[i].green;
608      buf[2] = pal_ptr[i].blue;
609      png_write_chunk_data(png_ptr, buf, (png_size_t)3);
610   }
611#endif
612   png_write_chunk_end(png_ptr);
613   png_ptr->mode |= PNG_HAVE_PLTE;
614}
615
616/* write an IDAT chunk */
617void /* PRIVATE */
618png_write_IDAT(png_structp png_ptr, png_bytep data, png_size_t length)
619{
620#ifdef PNG_USE_LOCAL_ARRAYS
621   PNG_IDAT;
622#endif
623   png_debug(1, "in png_write_IDAT\n");
624
625   /* Optimize the CMF field in the zlib stream. */
626   /* This hack of the zlib stream is compliant to the stream specification. */
627   if (!(png_ptr->mode & PNG_HAVE_IDAT) &&
628       png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
629   {
630      unsigned int z_cmf = data[0];  /* zlib compression method and flags */
631      if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
632      {
633         /* Avoid memory underflows and multiplication overflows. */
634         /* The conditions below are practically always satisfied;
635            however, they still must be checked. */
636         if (length >= 2 &&
637             png_ptr->height < 16384 && png_ptr->width < 16384)
638         {
639            png_uint_32 uncompressed_idat_size = png_ptr->height *
640               ((png_ptr->width *
641               png_ptr->channels * png_ptr->bit_depth + 15) >> 3);
642            unsigned int z_cinfo = z_cmf >> 4;
643            unsigned int half_z_window_size = 1 << (z_cinfo + 7);
644            while (uncompressed_idat_size <= half_z_window_size &&
645                   half_z_window_size >= 256)
646            {
647               z_cinfo--;
648               half_z_window_size >>= 1;
649            }
650            z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
651            if (data[0] != (png_byte)z_cmf)
652            {
653               data[0] = (png_byte)z_cmf;
654               data[1] &= 0xe0;
655               data[1] += (png_byte)(0x1f - ((z_cmf << 8) + data[1]) % 0x1f);
656            }
657         }
658      }
659      else
660         png_error(png_ptr,
661            "Invalid zlib compression method or flags in IDAT");
662   }
663
664   png_write_chunk(png_ptr, png_IDAT, data, length);
665   png_ptr->mode |= PNG_HAVE_IDAT;
666}
667
668/* write an IEND chunk */
669void /* PRIVATE */
670png_write_IEND(png_structp png_ptr)
671{
672#ifdef PNG_USE_LOCAL_ARRAYS
673   PNG_IEND;
674#endif
675   png_debug(1, "in png_write_IEND\n");
676   png_write_chunk(png_ptr, png_IEND, png_bytep_NULL,
677     (png_size_t)0);
678   png_ptr->mode |= PNG_HAVE_IEND;
679}
680
681#if defined(PNG_WRITE_gAMA_SUPPORTED)
682/* write a gAMA chunk */
683#ifdef PNG_FLOATING_POINT_SUPPORTED
684void /* PRIVATE */
685png_write_gAMA(png_structp png_ptr, double file_gamma)
686{
687#ifdef PNG_USE_LOCAL_ARRAYS
688   PNG_gAMA;
689#endif
690   png_uint_32 igamma;
691   png_byte buf[4];
692
693   png_debug(1, "in png_write_gAMA\n");
694   /* file_gamma is saved in 1/100,000ths */
695   igamma = (png_uint_32)(file_gamma * 100000.0 + 0.5);
696   png_save_uint_32(buf, igamma);
697   png_write_chunk(png_ptr, png_gAMA, buf, (png_size_t)4);
698}
699#endif
700#ifdef PNG_FIXED_POINT_SUPPORTED
701void /* PRIVATE */
702png_write_gAMA_fixed(png_structp png_ptr, png_fixed_point file_gamma)
703{
704#ifdef PNG_USE_LOCAL_ARRAYS
705   PNG_gAMA;
706#endif
707   png_byte buf[4];
708
709   png_debug(1, "in png_write_gAMA\n");
710   /* file_gamma is saved in 1/100,000ths */
711   png_save_uint_32(buf, (png_uint_32)file_gamma);
712   png_write_chunk(png_ptr, png_gAMA, buf, (png_size_t)4);
713}
714#endif
715#endif
716
717#if defined(PNG_WRITE_sRGB_SUPPORTED)
718/* write a sRGB chunk */
719void /* PRIVATE */
720png_write_sRGB(png_structp png_ptr, int srgb_intent)
721{
722#ifdef PNG_USE_LOCAL_ARRAYS
723   PNG_sRGB;
724#endif
725   png_byte buf[1];
726
727   png_debug(1, "in png_write_sRGB\n");
728   if(srgb_intent >= PNG_sRGB_INTENT_LAST)
729         png_warning(png_ptr,
730            "Invalid sRGB rendering intent specified");
731   buf[0]=(png_byte)srgb_intent;
732   png_write_chunk(png_ptr, png_sRGB, buf, (png_size_t)1);
733}
734#endif
735
736#if defined(PNG_WRITE_iCCP_SUPPORTED)
737/* write an iCCP chunk */
738void /* PRIVATE */
739png_write_iCCP(png_structp png_ptr, png_charp name, int compression_type,
740   png_charp profile, int profile_len)
741{
742#ifdef PNG_USE_LOCAL_ARRAYS
743   PNG_iCCP;
744#endif
745   png_size_t name_len;
746   png_charp new_name;
747   compression_state comp;
748   int embedded_profile_len = 0;
749
750   png_debug(1, "in png_write_iCCP\n");
751
752   comp.num_output_ptr = 0;
753   comp.max_output_ptr = 0;
754   comp.output_ptr = NULL;
755   comp.input = NULL;
756   comp.input_len = 0;
757
758   if (name == NULL || (name_len = png_check_keyword(png_ptr, name,
759      &new_name)) == 0)
760   {
761      png_warning(png_ptr, "Empty keyword in iCCP chunk");
762      return;
763   }
764
765   if (compression_type != PNG_COMPRESSION_TYPE_BASE)
766      png_warning(png_ptr, "Unknown compression type in iCCP chunk");
767
768   if (profile == NULL)
769      profile_len = 0;
770
771   if (profile_len > 3)
772      embedded_profile_len =
773          ((*( (png_bytep)profile  ))<<24) |
774          ((*( (png_bytep)profile+1))<<16) |
775          ((*( (png_bytep)profile+2))<< 8) |
776          ((*( (png_bytep)profile+3))    );
777
778   if (profile_len < embedded_profile_len)
779     {
780        png_warning(png_ptr,
781          "Embedded profile length too large in iCCP chunk");
782        return;
783     }
784
785   if (profile_len > embedded_profile_len)
786     {
787        png_warning(png_ptr,
788          "Truncating profile to actual length in iCCP chunk");
789        profile_len = embedded_profile_len;
790     }
791
792   if (profile_len)
793       profile_len = png_text_compress(png_ptr, profile, (png_size_t)profile_len,
794          PNG_COMPRESSION_TYPE_BASE, &comp);
795
796   /* make sure we include the NULL after the name and the compression type */
797   png_write_chunk_start(png_ptr, png_iCCP,
798          (png_uint_32)name_len+profile_len+2);
799   new_name[name_len+1]=0x00;
800   png_write_chunk_data(png_ptr, (png_bytep)new_name, name_len + 2);
801
802   if (profile_len)
803      png_write_compressed_data_out(png_ptr, &comp);
804
805   png_write_chunk_end(png_ptr);
806   png_free(png_ptr, new_name);
807}
808#endif
809
810#if defined(PNG_WRITE_sPLT_SUPPORTED)
811/* write a sPLT chunk */
812void /* PRIVATE */
813png_write_sPLT(png_structp png_ptr, png_sPLT_tp spalette)
814{
815#ifdef PNG_USE_LOCAL_ARRAYS
816   PNG_sPLT;
817#endif
818   png_size_t name_len;
819   png_charp new_name;
820   png_byte entrybuf[10];
821   int entry_size = (spalette->depth == 8 ? 6 : 10);
822   int palette_size = entry_size * spalette->nentries;
823   png_sPLT_entryp ep;
824#ifdef PNG_NO_POINTER_INDEXING
825   int i;
826#endif
827
828   png_debug(1, "in png_write_sPLT\n");
829   if (spalette->name == NULL || (name_len = png_check_keyword(png_ptr,
830      spalette->name, &new_name))==0)
831   {
832      png_warning(png_ptr, "Empty keyword in sPLT chunk");
833      return;
834   }
835
836   /* make sure we include the NULL after the name */
837   png_write_chunk_start(png_ptr, png_sPLT,
838          (png_uint_32)(name_len + 2 + palette_size));
839   png_write_chunk_data(png_ptr, (png_bytep)new_name, name_len + 1);
840   png_write_chunk_data(png_ptr, (png_bytep)&spalette->depth, 1);
841
842   /* loop through each palette entry, writing appropriately */
843#ifndef PNG_NO_POINTER_INDEXING
844   for (ep = spalette->entries; ep<spalette->entries+spalette->nentries; ep++)
845   {
846       if (spalette->depth == 8)
847       {
848           entrybuf[0] = (png_byte)ep->red;
849           entrybuf[1] = (png_byte)ep->green;
850           entrybuf[2] = (png_byte)ep->blue;
851           entrybuf[3] = (png_byte)ep->alpha;
852           png_save_uint_16(entrybuf + 4, ep->frequency);
853       }
854       else
855       {
856           png_save_uint_16(entrybuf + 0, ep->red);
857           png_save_uint_16(entrybuf + 2, ep->green);
858           png_save_uint_16(entrybuf + 4, ep->blue);
859           png_save_uint_16(entrybuf + 6, ep->alpha);
860           png_save_uint_16(entrybuf + 8, ep->frequency);
861       }
862       png_write_chunk_data(png_ptr, entrybuf, (png_size_t)entry_size);
863   }
864#else
865   ep=spalette->entries;
866   for (i=0; i>spalette->nentries; i++)
867   {
868       if (spalette->depth == 8)
869       {
870           entrybuf[0] = (png_byte)ep[i].red;
871           entrybuf[1] = (png_byte)ep[i].green;
872           entrybuf[2] = (png_byte)ep[i].blue;
873           entrybuf[3] = (png_byte)ep[i].alpha;
874           png_save_uint_16(entrybuf + 4, ep[i].frequency);
875       }
876       else
877       {
878           png_save_uint_16(entrybuf + 0, ep[i].red);
879           png_save_uint_16(entrybuf + 2, ep[i].green);
880           png_save_uint_16(entrybuf + 4, ep[i].blue);
881           png_save_uint_16(entrybuf + 6, ep[i].alpha);
882           png_save_uint_16(entrybuf + 8, ep[i].frequency);
883       }
884       png_write_chunk_data(png_ptr, entrybuf, entry_size);
885   }
886#endif
887
888   png_write_chunk_end(png_ptr);
889   png_free(png_ptr, new_name);
890}
891#endif
892
893#if defined(PNG_WRITE_sBIT_SUPPORTED)
894/* write the sBIT chunk */
895void /* PRIVATE */
896png_write_sBIT(png_structp png_ptr, png_color_8p sbit, int color_type)
897{
898#ifdef PNG_USE_LOCAL_ARRAYS
899   PNG_sBIT;
900#endif
901   png_byte buf[4];
902   png_size_t size;
903
904   png_debug(1, "in png_write_sBIT\n");
905   /* make sure we don't depend upon the order of PNG_COLOR_8 */
906   if (color_type & PNG_COLOR_MASK_COLOR)
907   {
908      png_byte maxbits;
909
910      maxbits = (png_byte)(color_type==PNG_COLOR_TYPE_PALETTE ? 8 :
911                png_ptr->usr_bit_depth);
912      if (sbit->red == 0 || sbit->red > maxbits ||
913          sbit->green == 0 || sbit->green > maxbits ||
914          sbit->blue == 0 || sbit->blue > maxbits)
915      {
916         png_warning(png_ptr, "Invalid sBIT depth specified");
917         return;
918      }
919      buf[0] = sbit->red;
920      buf[1] = sbit->green;
921      buf[2] = sbit->blue;
922      size = 3;
923   }
924   else
925   {
926      if (sbit->gray == 0 || sbit->gray > png_ptr->usr_bit_depth)
927      {
928         png_warning(png_ptr, "Invalid sBIT depth specified");
929         return;
930      }
931      buf[0] = sbit->gray;
932      size = 1;
933   }
934
935   if (color_type & PNG_COLOR_MASK_ALPHA)
936   {
937      if (sbit->alpha == 0 || sbit->alpha > png_ptr->usr_bit_depth)
938      {
939         png_warning(png_ptr, "Invalid sBIT depth specified");
940         return;
941      }
942      buf[size++] = sbit->alpha;
943   }
944
945   png_write_chunk(png_ptr, png_sBIT, buf, size);
946}
947#endif
948
949#if defined(PNG_WRITE_cHRM_SUPPORTED)
950/* write the cHRM chunk */
951#ifdef PNG_FLOATING_POINT_SUPPORTED
952void /* PRIVATE */
953png_write_cHRM(png_structp png_ptr, double white_x, double white_y,
954   double red_x, double red_y, double green_x, double green_y,
955   double blue_x, double blue_y)
956{
957#ifdef PNG_USE_LOCAL_ARRAYS
958   PNG_cHRM;
959#endif
960   png_byte buf[32];
961   png_uint_32 itemp;
962
963   png_debug(1, "in png_write_cHRM\n");
964   /* each value is saved in 1/100,000ths */
965   if (white_x < 0 || white_x > 0.8 || white_y < 0 || white_y > 0.8 ||
966       white_x + white_y > 1.0)
967   {
968      png_warning(png_ptr, "Invalid cHRM white point specified");
969#if !defined(PNG_NO_CONSOLE_IO)
970      fprintf(stderr,"white_x=%f, white_y=%f\n",white_x, white_y);
971#endif
972      return;
973   }
974   itemp = (png_uint_32)(white_x * 100000.0 + 0.5);
975   png_save_uint_32(buf, itemp);
976   itemp = (png_uint_32)(white_y * 100000.0 + 0.5);
977   png_save_uint_32(buf + 4, itemp);
978
979   if (red_x < 0 ||  red_y < 0 || red_x + red_y > 1.0)
980   {
981      png_warning(png_ptr, "Invalid cHRM red point specified");
982      return;
983   }
984   itemp = (png_uint_32)(red_x * 100000.0 + 0.5);
985   png_save_uint_32(buf + 8, itemp);
986   itemp = (png_uint_32)(red_y * 100000.0 + 0.5);
987   png_save_uint_32(buf + 12, itemp);
988
989   if (green_x < 0 || green_y < 0 || green_x + green_y > 1.0)
990   {
991      png_warning(png_ptr, "Invalid cHRM green point specified");
992      return;
993   }
994   itemp = (png_uint_32)(green_x * 100000.0 + 0.5);
995   png_save_uint_32(buf + 16, itemp);
996   itemp = (png_uint_32)(green_y * 100000.0 + 0.5);
997   png_save_uint_32(buf + 20, itemp);
998
999   if (blue_x < 0 || blue_y < 0 || blue_x + blue_y > 1.0)
1000   {
1001      png_warning(png_ptr, "Invalid cHRM blue point specified");
1002      return;
1003   }
1004   itemp = (png_uint_32)(blue_x * 100000.0 + 0.5);
1005   png_save_uint_32(buf + 24, itemp);
1006   itemp = (png_uint_32)(blue_y * 100000.0 + 0.5);
1007   png_save_uint_32(buf + 28, itemp);
1008
1009   png_write_chunk(png_ptr, png_cHRM, buf, (png_size_t)32);
1010}
1011#endif
1012#ifdef PNG_FIXED_POINT_SUPPORTED
1013void /* PRIVATE */
1014png_write_cHRM_fixed(png_structp png_ptr, png_fixed_point white_x,
1015   png_fixed_point white_y, png_fixed_point red_x, png_fixed_point red_y,
1016   png_fixed_point green_x, png_fixed_point green_y, png_fixed_point blue_x,
1017   png_fixed_point blue_y)
1018{
1019#ifdef PNG_USE_LOCAL_ARRAYS
1020   PNG_cHRM;
1021#endif
1022   png_byte buf[32];
1023
1024   png_debug(1, "in png_write_cHRM\n");
1025   /* each value is saved in 1/100,000ths */
1026   if (white_x > 80000L || white_y > 80000L || white_x + white_y > 100000L)
1027   {
1028      png_warning(png_ptr, "Invalid fixed cHRM white point specified");
1029#if !defined(PNG_NO_CONSOLE_IO)
1030      fprintf(stderr,"white_x=%ld, white_y=%ld\n",white_x, white_y);
1031#endif
1032      return;
1033   }
1034   png_save_uint_32(buf, (png_uint_32)white_x);
1035   png_save_uint_32(buf + 4, (png_uint_32)white_y);
1036
1037   if (red_x + red_y > 100000L)
1038   {
1039      png_warning(png_ptr, "Invalid cHRM fixed red point specified");
1040      return;
1041   }
1042   png_save_uint_32(buf + 8, (png_uint_32)red_x);
1043   png_save_uint_32(buf + 12, (png_uint_32)red_y);
1044
1045   if (green_x + green_y > 100000L)
1046   {
1047      png_warning(png_ptr, "Invalid fixed cHRM green point specified");
1048      return;
1049   }
1050   png_save_uint_32(buf + 16, (png_uint_32)green_x);
1051   png_save_uint_32(buf + 20, (png_uint_32)green_y);
1052
1053   if (blue_x + blue_y > 100000L)
1054   {
1055      png_warning(png_ptr, "Invalid fixed cHRM blue point specified");
1056      return;
1057   }
1058   png_save_uint_32(buf + 24, (png_uint_32)blue_x);
1059   png_save_uint_32(buf + 28, (png_uint_32)blue_y);
1060
1061   png_write_chunk(png_ptr, png_cHRM, buf, (png_size_t)32);
1062}
1063#endif
1064#endif
1065
1066#if defined(PNG_WRITE_tRNS_SUPPORTED)
1067/* write the tRNS chunk */
1068void /* PRIVATE */
1069png_write_tRNS(png_structp png_ptr, png_bytep trans, png_color_16p tran,
1070   int num_trans, int color_type)
1071{
1072#ifdef PNG_USE_LOCAL_ARRAYS
1073   PNG_tRNS;
1074#endif
1075   png_byte buf[6];
1076
1077   png_debug(1, "in png_write_tRNS\n");
1078   if (color_type == PNG_COLOR_TYPE_PALETTE)
1079   {
1080      if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette)
1081      {
1082         png_warning(png_ptr,"Invalid number of transparent colors specified");
1083         return;
1084      }
1085      /* write the chunk out as it is */
1086      png_write_chunk(png_ptr, png_tRNS, trans, (png_size_t)num_trans);
1087   }
1088   else if (color_type == PNG_COLOR_TYPE_GRAY)
1089   {
1090      /* one 16 bit value */
1091      if(tran->gray >= (1 << png_ptr->bit_depth))
1092      {
1093         png_warning(png_ptr,
1094           "Ignoring attempt to write tRNS chunk out-of-range for bit_depth");
1095         return;
1096      }
1097      png_save_uint_16(buf, tran->gray);
1098      png_write_chunk(png_ptr, png_tRNS, buf, (png_size_t)2);
1099   }
1100   else if (color_type == PNG_COLOR_TYPE_RGB)
1101   {
1102      /* three 16 bit values */
1103      png_save_uint_16(buf, tran->red);
1104      png_save_uint_16(buf + 2, tran->green);
1105      png_save_uint_16(buf + 4, tran->blue);
1106      if(png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))
1107         {
1108            png_warning(png_ptr,
1109              "Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8");
1110            return;
1111         }
1112      png_write_chunk(png_ptr, png_tRNS, buf, (png_size_t)6);
1113   }
1114   else
1115   {
1116      png_warning(png_ptr, "Can't write tRNS with an alpha channel");
1117   }
1118}
1119#endif
1120
1121#if defined(PNG_WRITE_bKGD_SUPPORTED)
1122/* write the background chunk */
1123void /* PRIVATE */
1124png_write_bKGD(png_structp png_ptr, png_color_16p back, int color_type)
1125{
1126#ifdef PNG_USE_LOCAL_ARRAYS
1127   PNG_bKGD;
1128#endif
1129   png_byte buf[6];
1130
1131   png_debug(1, "in png_write_bKGD\n");
1132   if (color_type == PNG_COLOR_TYPE_PALETTE)
1133   {
1134      if (
1135#if defined(PNG_MNG_FEATURES_SUPPORTED)
1136          (png_ptr->num_palette ||
1137          (!(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE))) &&
1138#endif
1139         back->index > png_ptr->num_palette)
1140      {
1141         png_warning(png_ptr, "Invalid background palette index");
1142         return;
1143      }
1144      buf[0] = back->index;
1145      png_write_chunk(png_ptr, png_bKGD, buf, (png_size_t)1);
1146   }
1147   else if (color_type & PNG_COLOR_MASK_COLOR)
1148   {
1149      png_save_uint_16(buf, back->red);
1150      png_save_uint_16(buf + 2, back->green);
1151      png_save_uint_16(buf + 4, back->blue);
1152      if(png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))
1153         {
1154            png_warning(png_ptr,
1155              "Ignoring attempt to write 16-bit bKGD chunk when bit_depth is 8");
1156            return;
1157         }
1158      png_write_chunk(png_ptr, png_bKGD, buf, (png_size_t)6);
1159   }
1160   else
1161   {
1162      if(back->gray >= (1 << png_ptr->bit_depth))
1163      {
1164         png_warning(png_ptr,
1165           "Ignoring attempt to write bKGD chunk out-of-range for bit_depth");
1166         return;
1167      }
1168      png_save_uint_16(buf, back->gray);
1169      png_write_chunk(png_ptr, png_bKGD, buf, (png_size_t)2);
1170   }
1171}
1172#endif
1173
1174#if defined(PNG_WRITE_hIST_SUPPORTED)
1175/* write the histogram */
1176void /* PRIVATE */
1177png_write_hIST(png_structp png_ptr, png_uint_16p hist, int num_hist)
1178{
1179#ifdef PNG_USE_LOCAL_ARRAYS
1180   PNG_hIST;
1181#endif
1182   int i;
1183   png_byte buf[3];
1184
1185   png_debug(1, "in png_write_hIST\n");
1186   if (num_hist > (int)png_ptr->num_palette)
1187   {
1188      png_debug2(3, "num_hist = %d, num_palette = %d\n", num_hist,
1189         png_ptr->num_palette);
1190      png_warning(png_ptr, "Invalid number of histogram entries specified");
1191      return;
1192   }
1193
1194   png_write_chunk_start(png_ptr, png_hIST, (png_uint_32)(num_hist * 2));
1195   for (i = 0; i < num_hist; i++)
1196   {
1197      png_save_uint_16(buf, hist[i]);
1198      png_write_chunk_data(png_ptr, buf, (png_size_t)2);
1199   }
1200   png_write_chunk_end(png_ptr);
1201}
1202#endif
1203
1204#if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \
1205    defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
1206/* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification,
1207 * and if invalid, correct the keyword rather than discarding the entire
1208 * chunk.  The PNG 1.0 specification requires keywords 1-79 characters in
1209 * length, forbids leading or trailing whitespace, multiple internal spaces,
1210 * and the non-break space (0x80) from ISO 8859-1.  Returns keyword length.
1211 *
1212 * The new_key is allocated to hold the corrected keyword and must be freed
1213 * by the calling routine.  This avoids problems with trying to write to
1214 * static keywords without having to have duplicate copies of the strings.
1215 */
1216png_size_t /* PRIVATE */
1217png_check_keyword(png_structp png_ptr, png_charp key, png_charpp new_key)
1218{
1219   png_size_t key_len;
1220   png_charp kp, dp;
1221   int kflag;
1222   int kwarn=0;
1223
1224   png_debug(1, "in png_check_keyword\n");
1225   *new_key = NULL;
1226
1227   if (key == NULL || (key_len = png_strlen(key)) == 0)
1228   {
1229      png_warning(png_ptr, "zero length keyword");
1230      return ((png_size_t)0);
1231   }
1232
1233   png_debug1(2, "Keyword to be checked is '%s'\n", key);
1234
1235   *new_key = (png_charp)png_malloc_warn(png_ptr, (png_uint_32)(key_len + 2));
1236   if (*new_key == NULL)
1237   {
1238      png_warning(png_ptr, "Out of memory while procesing keyword");
1239      return ((png_size_t)0);
1240   }
1241
1242   /* Replace non-printing characters with a blank and print a warning */
1243   for (kp = key, dp = *new_key; *kp != '\0'; kp++, dp++)
1244   {
1245      if ((png_byte)*kp < 0x20 ||
1246         ((png_byte)*kp > 0x7E && (png_byte)*kp < 0xA1))
1247      {
1248#if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
1249         char msg[40];
1250
1251         png_snprintf(msg, 40,
1252           "invalid keyword character 0x%02X", (png_byte)*kp);
1253         png_warning(png_ptr, msg);
1254#else
1255         png_warning(png_ptr, "invalid character in keyword");
1256#endif
1257         *dp = ' ';
1258      }
1259      else
1260      {
1261         *dp = *kp;
1262      }
1263   }
1264   *dp = '\0';
1265
1266   /* Remove any trailing white space. */
1267   kp = *new_key + key_len - 1;
1268   if (*kp == ' ')
1269   {
1270      png_warning(png_ptr, "trailing spaces removed from keyword");
1271
1272      while (*kp == ' ')
1273      {
1274        *(kp--) = '\0';
1275        key_len--;
1276      }
1277   }
1278
1279   /* Remove any leading white space. */
1280   kp = *new_key;
1281   if (*kp == ' ')
1282   {
1283      png_warning(png_ptr, "leading spaces removed from keyword");
1284
1285      while (*kp == ' ')
1286      {
1287        kp++;
1288        key_len--;
1289      }
1290   }
1291
1292   png_debug1(2, "Checking for multiple internal spaces in '%s'\n", kp);
1293
1294   /* Remove multiple internal spaces. */
1295   for (kflag = 0, dp = *new_key; *kp != '\0'; kp++)
1296   {
1297      if (*kp == ' ' && kflag == 0)
1298      {
1299         *(dp++) = *kp;
1300         kflag = 1;
1301      }
1302      else if (*kp == ' ')
1303      {
1304         key_len--;
1305         kwarn=1;
1306      }
1307      else
1308      {
1309         *(dp++) = *kp;
1310         kflag = 0;
1311      }
1312   }
1313   *dp = '\0';
1314   if(kwarn)
1315      png_warning(png_ptr, "extra interior spaces removed from keyword");
1316
1317   if (key_len == 0)
1318   {
1319      png_free(png_ptr, *new_key);
1320      *new_key=NULL;
1321      png_warning(png_ptr, "Zero length keyword");
1322   }
1323
1324   if (key_len > 79)
1325   {
1326      png_warning(png_ptr, "keyword length must be 1 - 79 characters");
1327      new_key[79] = '\0';
1328      key_len = 79;
1329   }
1330
1331   return (key_len);
1332}
1333#endif
1334
1335#if defined(PNG_WRITE_tEXt_SUPPORTED)
1336/* write a tEXt chunk */
1337void /* PRIVATE */
1338png_write_tEXt(png_structp png_ptr, png_charp key, png_charp text,
1339   png_size_t text_len)
1340{
1341#ifdef PNG_USE_LOCAL_ARRAYS
1342   PNG_tEXt;
1343#endif
1344   png_size_t key_len;
1345   png_charp new_key;
1346
1347   png_debug(1, "in png_write_tEXt\n");
1348   if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0)
1349   {
1350      png_warning(png_ptr, "Empty keyword in tEXt chunk");
1351      return;
1352   }
1353
1354   if (text == NULL || *text == '\0')
1355      text_len = 0;
1356   else
1357      text_len = png_strlen(text);
1358
1359   /* make sure we include the 0 after the key */
1360   png_write_chunk_start(png_ptr, png_tEXt, (png_uint_32)key_len+text_len+1);
1361   /*
1362    * We leave it to the application to meet PNG-1.0 requirements on the
1363    * contents of the text.  PNG-1.0 through PNG-1.2 discourage the use of
1364    * any non-Latin-1 characters except for NEWLINE.  ISO PNG will forbid them.
1365    * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1366    */
1367   png_write_chunk_data(png_ptr, (png_bytep)new_key, key_len + 1);
1368   if (text_len)
1369      png_write_chunk_data(png_ptr, (png_bytep)text, text_len);
1370
1371   png_write_chunk_end(png_ptr);
1372   png_free(png_ptr, new_key);
1373}
1374#endif
1375
1376#if defined(PNG_WRITE_zTXt_SUPPORTED)
1377/* write a compressed text chunk */
1378void /* PRIVATE */
1379png_write_zTXt(png_structp png_ptr, png_charp key, png_charp text,
1380   png_size_t text_len, int compression)
1381{
1382#ifdef PNG_USE_LOCAL_ARRAYS
1383   PNG_zTXt;
1384#endif
1385   png_size_t key_len;
1386   char buf[1];
1387   png_charp new_key;
1388   compression_state comp;
1389
1390   png_debug(1, "in png_write_zTXt\n");
1391
1392   comp.num_output_ptr = 0;
1393   comp.max_output_ptr = 0;
1394   comp.output_ptr = NULL;
1395   comp.input = NULL;
1396   comp.input_len = 0;
1397
1398   if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0)
1399   {
1400      png_warning(png_ptr, "Empty keyword in zTXt chunk");
1401      return;
1402   }
1403
1404   if (text == NULL || *text == '\0' || compression==PNG_TEXT_COMPRESSION_NONE)
1405   {
1406      png_write_tEXt(png_ptr, new_key, text, (png_size_t)0);
1407      png_free(png_ptr, new_key);
1408      return;
1409   }
1410
1411   text_len = png_strlen(text);
1412
1413   /* compute the compressed data; do it now for the length */
1414   text_len = png_text_compress(png_ptr, text, text_len, compression,
1415       &comp);
1416
1417   /* write start of chunk */
1418   png_write_chunk_start(png_ptr, png_zTXt, (png_uint_32)
1419      (key_len+text_len+2));
1420   /* write key */
1421   png_write_chunk_data(png_ptr, (png_bytep)new_key, key_len + 1);
1422   png_free(png_ptr, new_key);
1423
1424   buf[0] = (png_byte)compression;
1425   /* write compression */
1426   png_write_chunk_data(png_ptr, (png_bytep)buf, (png_size_t)1);
1427   /* write the compressed data */
1428   png_write_compressed_data_out(png_ptr, &comp);
1429
1430   /* close the chunk */
1431   png_write_chunk_end(png_ptr);
1432}
1433#endif
1434
1435#if defined(PNG_WRITE_iTXt_SUPPORTED)
1436/* write an iTXt chunk */
1437void /* PRIVATE */
1438png_write_iTXt(png_structp png_ptr, int compression, png_charp key,
1439    png_charp lang, png_charp lang_key, png_charp text)
1440{
1441#ifdef PNG_USE_LOCAL_ARRAYS
1442   PNG_iTXt;
1443#endif
1444   png_size_t lang_len, key_len, lang_key_len, text_len;
1445   png_charp new_lang, new_key;
1446   png_byte cbuf[2];
1447   compression_state comp;
1448
1449   png_debug(1, "in png_write_iTXt\n");
1450
1451   comp.num_output_ptr = 0;
1452   comp.max_output_ptr = 0;
1453   comp.output_ptr = NULL;
1454   comp.input = NULL;
1455
1456   if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0)
1457   {
1458      png_warning(png_ptr, "Empty keyword in iTXt chunk");
1459      return;
1460   }
1461   if (lang == NULL || (lang_len = png_check_keyword(png_ptr, lang, &new_lang))==0)
1462   {
1463      png_warning(png_ptr, "Empty language field in iTXt chunk");
1464      new_lang = NULL;
1465      lang_len = 0;
1466   }
1467
1468   if (lang_key == NULL)
1469     lang_key_len = 0;
1470   else
1471     lang_key_len = png_strlen(lang_key);
1472
1473   if (text == NULL)
1474      text_len = 0;
1475   else
1476     text_len = png_strlen(text);
1477
1478   /* compute the compressed data; do it now for the length */
1479   text_len = png_text_compress(png_ptr, text, text_len, compression-2,
1480      &comp);
1481
1482
1483   /* make sure we include the compression flag, the compression byte,
1484    * and the NULs after the key, lang, and lang_key parts */
1485
1486   png_write_chunk_start(png_ptr, png_iTXt,
1487          (png_uint_32)(
1488        5 /* comp byte, comp flag, terminators for key, lang and lang_key */
1489        + key_len
1490        + lang_len
1491        + lang_key_len
1492        + text_len));
1493
1494   /*
1495    * We leave it to the application to meet PNG-1.0 requirements on the
1496    * contents of the text.  PNG-1.0 through PNG-1.2 discourage the use of
1497    * any non-Latin-1 characters except for NEWLINE.  ISO PNG will forbid them.
1498    * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1499    */
1500   png_write_chunk_data(png_ptr, (png_bytep)new_key, key_len + 1);
1501
1502   /* set the compression flag */
1503   if (compression == PNG_ITXT_COMPRESSION_NONE || \
1504       compression == PNG_TEXT_COMPRESSION_NONE)
1505       cbuf[0] = 0;
1506   else /* compression == PNG_ITXT_COMPRESSION_zTXt */
1507       cbuf[0] = 1;
1508   /* set the compression method */
1509   cbuf[1] = 0;
1510   png_write_chunk_data(png_ptr, cbuf, 2);
1511
1512   cbuf[0] = 0;
1513   png_write_chunk_data(png_ptr, (new_lang ? (png_bytep)new_lang : cbuf), lang_len + 1);
1514   png_write_chunk_data(png_ptr, (lang_key ? (png_bytep)lang_key : cbuf), lang_key_len + 1);
1515   png_write_compressed_data_out(png_ptr, &comp);
1516
1517   png_write_chunk_end(png_ptr);
1518   png_free(png_ptr, new_key);
1519   png_free(png_ptr, new_lang);
1520}
1521#endif
1522
1523#if defined(PNG_WRITE_oFFs_SUPPORTED)
1524/* write the oFFs chunk */
1525void /* PRIVATE */
1526png_write_oFFs(png_structp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
1527   int unit_type)
1528{
1529#ifdef PNG_USE_LOCAL_ARRAYS
1530   PNG_oFFs;
1531#endif
1532   png_byte buf[9];
1533
1534   png_debug(1, "in png_write_oFFs\n");
1535   if (unit_type >= PNG_OFFSET_LAST)
1536      png_warning(png_ptr, "Unrecognized unit type for oFFs chunk");
1537
1538   png_save_int_32(buf, x_offset);
1539   png_save_int_32(buf + 4, y_offset);
1540   buf[8] = (png_byte)unit_type;
1541
1542   png_write_chunk(png_ptr, png_oFFs, buf, (png_size_t)9);
1543}
1544#endif
1545#if defined(PNG_WRITE_pCAL_SUPPORTED)
1546/* write the pCAL chunk (described in the PNG extensions document) */
1547void /* PRIVATE */
1548png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
1549   png_int_32 X1, int type, int nparams, png_charp units, png_charpp params)
1550{
1551#ifdef PNG_USE_LOCAL_ARRAYS
1552   PNG_pCAL;
1553#endif
1554   png_size_t purpose_len, units_len, total_len;
1555   png_uint_32p params_len;
1556   png_byte buf[10];
1557   png_charp new_purpose;
1558   int i;
1559
1560   png_debug1(1, "in png_write_pCAL (%d parameters)\n", nparams);
1561   if (type >= PNG_EQUATION_LAST)
1562      png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");
1563
1564   purpose_len = png_check_keyword(png_ptr, purpose, &new_purpose) + 1;
1565   png_debug1(3, "pCAL purpose length = %d\n", (int)purpose_len);
1566   units_len = png_strlen(units) + (nparams == 0 ? 0 : 1);
1567   png_debug1(3, "pCAL units length = %d\n", (int)units_len);
1568   total_len = purpose_len + units_len + 10;
1569
1570   params_len = (png_uint_32p)png_malloc(png_ptr, (png_uint_32)(nparams
1571      *png_sizeof(png_uint_32)));
1572
1573   /* Find the length of each parameter, making sure we don't count the
1574      null terminator for the last parameter. */
1575   for (i = 0; i < nparams; i++)
1576   {
1577      params_len[i] = png_strlen(params[i]) + (i == nparams - 1 ? 0 : 1);
1578      png_debug2(3, "pCAL parameter %d length = %lu\n", i, params_len[i]);
1579      total_len += (png_size_t)params_len[i];
1580   }
1581
1582   png_debug1(3, "pCAL total length = %d\n", (int)total_len);
1583   png_write_chunk_start(png_ptr, png_pCAL, (png_uint_32)total_len);
1584   png_write_chunk_data(png_ptr, (png_bytep)new_purpose, purpose_len);
1585   png_save_int_32(buf, X0);
1586   png_save_int_32(buf + 4, X1);
1587   buf[8] = (png_byte)type;
1588   buf[9] = (png_byte)nparams;
1589   png_write_chunk_data(png_ptr, buf, (png_size_t)10);
1590   png_write_chunk_data(png_ptr, (png_bytep)units, (png_size_t)units_len);
1591
1592   png_free(png_ptr, new_purpose);
1593
1594   for (i = 0; i < nparams; i++)
1595   {
1596      png_write_chunk_data(png_ptr, (png_bytep)params[i],
1597         (png_size_t)params_len[i]);
1598   }
1599
1600   png_free(png_ptr, params_len);
1601   png_write_chunk_end(png_ptr);
1602}
1603#endif
1604
1605#if defined(PNG_WRITE_sCAL_SUPPORTED)
1606/* write the sCAL chunk */
1607#if defined(PNG_FLOATING_POINT_SUPPORTED) && !defined(PNG_NO_STDIO)
1608void /* PRIVATE */
1609png_write_sCAL(png_structp png_ptr, int unit, double width, double height)
1610{
1611#ifdef PNG_USE_LOCAL_ARRAYS
1612   PNG_sCAL;
1613#endif
1614   char buf[64];
1615   png_size_t total_len;
1616
1617   png_debug(1, "in png_write_sCAL\n");
1618
1619   buf[0] = (char)unit;
1620#if defined(_WIN32_WCE)
1621/* sprintf() function is not supported on WindowsCE */
1622   {
1623      wchar_t wc_buf[32];
1624      size_t wc_len;
1625      swprintf(wc_buf, TEXT("%12.12e"), width);
1626      wc_len = wcslen(wc_buf);
1627      WideCharToMultiByte(CP_ACP, 0, wc_buf, -1, buf + 1, wc_len, NULL, NULL);
1628      total_len = wc_len + 2;
1629      swprintf(wc_buf, TEXT("%12.12e"), height);
1630      wc_len = wcslen(wc_buf);
1631      WideCharToMultiByte(CP_ACP, 0, wc_buf, -1, buf + total_len, wc_len,
1632         NULL, NULL);
1633      total_len += wc_len;
1634   }
1635#else
1636   png_snprintf(buf + 1, 63, "%12.12e", width);
1637   total_len = 1 + png_strlen(buf + 1) + 1;
1638   png_snprintf(buf + total_len, 64-total_len, "%12.12e", height);
1639   total_len += png_strlen(buf + total_len);
1640#endif
1641
1642   png_debug1(3, "sCAL total length = %u\n", (unsigned int)total_len);
1643   png_write_chunk(png_ptr, png_sCAL, (png_bytep)buf, total_len);
1644}
1645#else
1646#ifdef PNG_FIXED_POINT_SUPPORTED
1647void /* PRIVATE */
1648png_write_sCAL_s(png_structp png_ptr, int unit, png_charp width,
1649   png_charp height)
1650{
1651#ifdef PNG_USE_LOCAL_ARRAYS
1652   PNG_sCAL;
1653#endif
1654   png_byte buf[64];
1655   png_size_t wlen, hlen, total_len;
1656
1657   png_debug(1, "in png_write_sCAL_s\n");
1658
1659   wlen = png_strlen(width);
1660   hlen = png_strlen(height);
1661   total_len = wlen + hlen + 2;
1662   if (total_len > 64)
1663   {
1664      png_warning(png_ptr, "Can't write sCAL (buffer too small)");
1665      return;
1666   }
1667
1668   buf[0] = (png_byte)unit;
1669   png_memcpy(buf + 1, width, wlen + 1);      /* append the '\0' here */
1670   png_memcpy(buf + wlen + 2, height, hlen);  /* do NOT append the '\0' here */
1671
1672   png_debug1(3, "sCAL total length = %u\n", (unsigned int)total_len);
1673   png_write_chunk(png_ptr, png_sCAL, buf, total_len);
1674}
1675#endif
1676#endif
1677#endif
1678
1679#if defined(PNG_WRITE_pHYs_SUPPORTED)
1680/* write the pHYs chunk */
1681void /* PRIVATE */
1682png_write_pHYs(png_structp png_ptr, png_uint_32 x_pixels_per_unit,
1683   png_uint_32 y_pixels_per_unit,
1684   int unit_type)
1685{
1686#ifdef PNG_USE_LOCAL_ARRAYS
1687   PNG_pHYs;
1688#endif
1689   png_byte buf[9];
1690
1691   png_debug(1, "in png_write_pHYs\n");
1692   if (unit_type >= PNG_RESOLUTION_LAST)
1693      png_warning(png_ptr, "Unrecognized unit type for pHYs chunk");
1694
1695   png_save_uint_32(buf, x_pixels_per_unit);
1696   png_save_uint_32(buf + 4, y_pixels_per_unit);
1697   buf[8] = (png_byte)unit_type;
1698
1699   png_write_chunk(png_ptr, png_pHYs, buf, (png_size_t)9);
1700}
1701#endif
1702
1703#if defined(PNG_WRITE_tIME_SUPPORTED)
1704/* Write the tIME chunk.  Use either png_convert_from_struct_tm()
1705 * or png_convert_from_time_t(), or fill in the structure yourself.
1706 */
1707void /* PRIVATE */
1708png_write_tIME(png_structp png_ptr, png_timep mod_time)
1709{
1710#ifdef PNG_USE_LOCAL_ARRAYS
1711   PNG_tIME;
1712#endif
1713   png_byte buf[7];
1714
1715   png_debug(1, "in png_write_tIME\n");
1716   if (mod_time->month  > 12 || mod_time->month  < 1 ||
1717       mod_time->day    > 31 || mod_time->day    < 1 ||
1718       mod_time->hour   > 23 || mod_time->second > 60)
1719   {
1720      png_warning(png_ptr, "Invalid time specified for tIME chunk");
1721      return;
1722   }
1723
1724   png_save_uint_16(buf, mod_time->year);
1725   buf[2] = mod_time->month;
1726   buf[3] = mod_time->day;
1727   buf[4] = mod_time->hour;
1728   buf[5] = mod_time->minute;
1729   buf[6] = mod_time->second;
1730
1731   png_write_chunk(png_ptr, png_tIME, buf, (png_size_t)7);
1732}
1733#endif
1734
1735/* initializes the row writing capability of libpng */
1736void /* PRIVATE */
1737png_write_start_row(png_structp png_ptr)
1738{
1739#ifdef PNG_WRITE_INTERLACING_SUPPORTED
1740#ifdef PNG_USE_LOCAL_ARRAYS
1741   /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1742
1743   /* start of interlace block */
1744   int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
1745
1746   /* offset to next interlace block */
1747   int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
1748
1749   /* start of interlace block in the y direction */
1750   int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
1751
1752   /* offset to next interlace block in the y direction */
1753   int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
1754#endif
1755#endif
1756
1757   png_size_t buf_size;
1758
1759   png_debug(1, "in png_write_start_row\n");
1760   buf_size = (png_size_t)(PNG_ROWBYTES(
1761      png_ptr->usr_channels*png_ptr->usr_bit_depth,png_ptr->width)+1);
1762
1763   /* set up row buffer */
1764   png_ptr->row_buf = (png_bytep)png_malloc(png_ptr, (png_uint_32)buf_size);
1765   png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE;
1766
1767#ifndef PNG_NO_WRITE_FILTERING
1768   /* set up filtering buffer, if using this filter */
1769   if (png_ptr->do_filter & PNG_FILTER_SUB)
1770   {
1771      png_ptr->sub_row = (png_bytep)png_malloc(png_ptr,
1772         (png_ptr->rowbytes + 1));
1773      png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
1774   }
1775
1776   /* We only need to keep the previous row if we are using one of these. */
1777   if (png_ptr->do_filter & (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH))
1778   {
1779     /* set up previous row buffer */
1780      png_ptr->prev_row = (png_bytep)png_malloc(png_ptr, (png_uint_32)buf_size);
1781      png_memset(png_ptr->prev_row, 0, buf_size);
1782
1783      if (png_ptr->do_filter & PNG_FILTER_UP)
1784      {
1785         png_ptr->up_row = (png_bytep)png_malloc(png_ptr,
1786            (png_ptr->rowbytes + 1));
1787         png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;
1788      }
1789
1790      if (png_ptr->do_filter & PNG_FILTER_AVG)
1791      {
1792         png_ptr->avg_row = (png_bytep)png_malloc(png_ptr,
1793            (png_ptr->rowbytes + 1));
1794         png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;
1795      }
1796
1797      if (png_ptr->do_filter & PNG_FILTER_PAETH)
1798      {
1799         png_ptr->paeth_row = (png_bytep)png_malloc(png_ptr,
1800            (png_ptr->rowbytes + 1));
1801         png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
1802      }
1803#endif /* PNG_NO_WRITE_FILTERING */
1804   }
1805
1806#ifdef PNG_WRITE_INTERLACING_SUPPORTED
1807   /* if interlaced, we need to set up width and height of pass */
1808   if (png_ptr->interlaced)
1809   {
1810      if (!(png_ptr->transformations & PNG_INTERLACE))
1811      {
1812         png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
1813            png_pass_ystart[0]) / png_pass_yinc[0];
1814         png_ptr->usr_width = (png_ptr->width + png_pass_inc[0] - 1 -
1815            png_pass_start[0]) / png_pass_inc[0];
1816      }
1817      else
1818      {
1819         png_ptr->num_rows = png_ptr->height;
1820         png_ptr->usr_width = png_ptr->width;
1821      }
1822   }
1823   else
1824#endif
1825   {
1826      png_ptr->num_rows = png_ptr->height;
1827      png_ptr->usr_width = png_ptr->width;
1828   }
1829   png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1830   png_ptr->zstream.next_out = png_ptr->zbuf;
1831}
1832
1833/* Internal use only.  Called when finished processing a row of data. */
1834void /* PRIVATE */
1835png_write_finish_row(png_structp png_ptr)
1836{
1837#ifdef PNG_WRITE_INTERLACING_SUPPORTED
1838#ifdef PNG_USE_LOCAL_ARRAYS
1839   /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1840
1841   /* start of interlace block */
1842   int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
1843
1844   /* offset to next interlace block */
1845   int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
1846
1847   /* start of interlace block in the y direction */
1848   int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
1849
1850   /* offset to next interlace block in the y direction */
1851   int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
1852#endif
1853#endif
1854
1855   int ret;
1856
1857   png_debug(1, "in png_write_finish_row\n");
1858   /* next row */
1859   png_ptr->row_number++;
1860
1861   /* see if we are done */
1862   if (png_ptr->row_number < png_ptr->num_rows)
1863      return;
1864
1865#ifdef PNG_WRITE_INTERLACING_SUPPORTED
1866   /* if interlaced, go to next pass */
1867   if (png_ptr->interlaced)
1868   {
1869      png_ptr->row_number = 0;
1870      if (png_ptr->transformations & PNG_INTERLACE)
1871      {
1872         png_ptr->pass++;
1873      }
1874      else
1875      {
1876         /* loop until we find a non-zero width or height pass */
1877         do
1878         {
1879            png_ptr->pass++;
1880            if (png_ptr->pass >= 7)
1881               break;
1882            png_ptr->usr_width = (png_ptr->width +
1883               png_pass_inc[png_ptr->pass] - 1 -
1884               png_pass_start[png_ptr->pass]) /
1885               png_pass_inc[png_ptr->pass];
1886            png_ptr->num_rows = (png_ptr->height +
1887               png_pass_yinc[png_ptr->pass] - 1 -
1888               png_pass_ystart[png_ptr->pass]) /
1889               png_pass_yinc[png_ptr->pass];
1890            if (png_ptr->transformations & PNG_INTERLACE)
1891               break;
1892         } while (png_ptr->usr_width == 0 || png_ptr->num_rows == 0);
1893
1894      }
1895
1896      /* reset the row above the image for the next pass */
1897      if (png_ptr->pass < 7)
1898      {
1899         if (png_ptr->prev_row != NULL)
1900            png_memset(png_ptr->prev_row, 0,
1901               (png_size_t)(PNG_ROWBYTES(png_ptr->usr_channels*
1902               png_ptr->usr_bit_depth,png_ptr->width))+1);
1903         return;
1904      }
1905   }
1906#endif
1907
1908   /* if we get here, we've just written the last row, so we need
1909      to flush the compressor */
1910   do
1911   {
1912      /* tell the compressor we are done */
1913      ret = deflate(&png_ptr->zstream, Z_FINISH);
1914      /* check for an error */
1915      if (ret == Z_OK)
1916      {
1917         /* check to see if we need more room */
1918         if (!(png_ptr->zstream.avail_out))
1919         {
1920            png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
1921            png_ptr->zstream.next_out = png_ptr->zbuf;
1922            png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1923         }
1924      }
1925      else if (ret != Z_STREAM_END)
1926      {
1927         if (png_ptr->zstream.msg != NULL)
1928            png_error(png_ptr, png_ptr->zstream.msg);
1929         else
1930            png_error(png_ptr, "zlib error");
1931      }
1932   } while (ret != Z_STREAM_END);
1933
1934   /* write any extra space */
1935   if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
1936   {
1937      png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size -
1938         png_ptr->zstream.avail_out);
1939   }
1940
1941   deflateReset(&png_ptr->zstream);
1942   png_ptr->zstream.data_type = Z_BINARY;
1943}
1944
1945#if defined(PNG_WRITE_INTERLACING_SUPPORTED)
1946/* Pick out the correct pixels for the interlace pass.
1947 * The basic idea here is to go through the row with a source
1948 * pointer and a destination pointer (sp and dp), and copy the
1949 * correct pixels for the pass.  As the row gets compacted,
1950 * sp will always be >= dp, so we should never overwrite anything.
1951 * See the default: case for the easiest code to understand.
1952 */
1953void /* PRIVATE */
1954png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
1955{
1956#ifdef PNG_USE_LOCAL_ARRAYS
1957   /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1958
1959   /* start of interlace block */
1960   int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
1961
1962   /* offset to next interlace block */
1963   int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
1964#endif
1965
1966   png_debug(1, "in png_do_write_interlace\n");
1967   /* we don't have to do anything on the last pass (6) */
1968#if defined(PNG_USELESS_TESTS_SUPPORTED)
1969   if (row != NULL && row_info != NULL && pass < 6)
1970#else
1971   if (pass < 6)
1972#endif
1973   {
1974      /* each pixel depth is handled separately */
1975      switch (row_info->pixel_depth)
1976      {
1977         case 1:
1978         {
1979            png_bytep sp;
1980            png_bytep dp;
1981            int shift;
1982            int d;
1983            int value;
1984            png_uint_32 i;
1985            png_uint_32 row_width = row_info->width;
1986
1987            dp = row;
1988            d = 0;
1989            shift = 7;
1990            for (i = png_pass_start[pass]; i < row_width;
1991               i += png_pass_inc[pass])
1992            {
1993               sp = row + (png_size_t)(i >> 3);
1994               value = (int)(*sp >> (7 - (int)(i & 0x07))) & 0x01;
1995               d |= (value << shift);
1996
1997               if (shift == 0)
1998               {
1999                  shift = 7;
2000                  *dp++ = (png_byte)d;
2001                  d = 0;
2002               }
2003               else
2004                  shift--;
2005
2006            }
2007            if (shift != 7)
2008               *dp = (png_byte)d;
2009            break;
2010         }
2011         case 2:
2012         {
2013            png_bytep sp;
2014            png_bytep dp;
2015            int shift;
2016            int d;
2017            int value;
2018            png_uint_32 i;
2019            png_uint_32 row_width = row_info->width;
2020
2021            dp = row;
2022            shift = 6;
2023            d = 0;
2024            for (i = png_pass_start[pass]; i < row_width;
2025               i += png_pass_inc[pass])
2026            {
2027               sp = row + (png_size_t)(i >> 2);
2028               value = (*sp >> ((3 - (int)(i & 0x03)) << 1)) & 0x03;
2029               d |= (value << shift);
2030
2031               if (shift == 0)
2032               {
2033                  shift = 6;
2034                  *dp++ = (png_byte)d;
2035                  d = 0;
2036               }
2037               else
2038                  shift -= 2;
2039            }
2040            if (shift != 6)
2041                   *dp = (png_byte)d;
2042            break;
2043         }
2044         case 4:
2045         {
2046            png_bytep sp;
2047            png_bytep dp;
2048            int shift;
2049            int d;
2050            int value;
2051            png_uint_32 i;
2052            png_uint_32 row_width = row_info->width;
2053
2054            dp = row;
2055            shift = 4;
2056            d = 0;
2057            for (i = png_pass_start[pass]; i < row_width;
2058               i += png_pass_inc[pass])
2059            {
2060               sp = row + (png_size_t)(i >> 1);
2061               value = (*sp >> ((1 - (int)(i & 0x01)) << 2)) & 0x0f;
2062               d |= (value << shift);
2063
2064               if (shift == 0)
2065               {
2066                  shift = 4;
2067                  *dp++ = (png_byte)d;
2068                  d = 0;
2069               }
2070               else
2071                  shift -= 4;
2072            }
2073            if (shift != 4)
2074               *dp = (png_byte)d;
2075            break;
2076         }
2077         default:
2078         {
2079            png_bytep sp;
2080            png_bytep dp;
2081            png_uint_32 i;
2082            png_uint_32 row_width = row_info->width;
2083            png_size_t pixel_bytes;
2084
2085            /* start at the beginning */
2086            dp = row;
2087            /* find out how many bytes each pixel takes up */
2088            pixel_bytes = (row_info->pixel_depth >> 3);
2089            /* loop through the row, only looking at the pixels that
2090               matter */
2091            for (i = png_pass_start[pass]; i < row_width;
2092               i += png_pass_inc[pass])
2093            {
2094               /* find out where the original pixel is */
2095               sp = row + (png_size_t)i * pixel_bytes;
2096               /* move the pixel */
2097               if (dp != sp)
2098                  png_memcpy(dp, sp, pixel_bytes);
2099               /* next pixel */
2100               dp += pixel_bytes;
2101            }
2102            break;
2103         }
2104      }
2105      /* set new row width */
2106      row_info->width = (row_info->width +
2107         png_pass_inc[pass] - 1 -
2108         png_pass_start[pass]) /
2109         png_pass_inc[pass];
2110         row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
2111            row_info->width);
2112   }
2113}
2114#endif
2115
2116/* This filters the row, chooses which filter to use, if it has not already
2117 * been specified by the application, and then writes the row out with the
2118 * chosen filter.
2119 */
2120#define PNG_MAXSUM (((png_uint_32)(-1)) >> 1)
2121#define PNG_HISHIFT 10
2122#define PNG_LOMASK ((png_uint_32)0xffffL)
2123#define PNG_HIMASK ((png_uint_32)(~PNG_LOMASK >> PNG_HISHIFT))
2124void /* PRIVATE */
2125png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
2126{
2127   png_bytep best_row;
2128#ifndef PNG_NO_WRITE_FILTER
2129   png_bytep prev_row, row_buf;
2130   png_uint_32 mins, bpp;
2131   png_byte filter_to_do = png_ptr->do_filter;
2132   png_uint_32 row_bytes = row_info->rowbytes;
2133#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2134   int num_p_filters = (int)png_ptr->num_prev_filters;
2135#endif
2136
2137   png_debug(1, "in png_write_find_filter\n");
2138   /* find out how many bytes offset each pixel is */
2139   bpp = (row_info->pixel_depth + 7) >> 3;
2140
2141   prev_row = png_ptr->prev_row;
2142#endif
2143   best_row = png_ptr->row_buf;
2144#ifndef PNG_NO_WRITE_FILTER
2145   row_buf = best_row;
2146   mins = PNG_MAXSUM;
2147
2148   /* The prediction method we use is to find which method provides the
2149    * smallest value when summing the absolute values of the distances
2150    * from zero, using anything >= 128 as negative numbers.  This is known
2151    * as the "minimum sum of absolute differences" heuristic.  Other
2152    * heuristics are the "weighted minimum sum of absolute differences"
2153    * (experimental and can in theory improve compression), and the "zlib
2154    * predictive" method (not implemented yet), which does test compressions
2155    * of lines using different filter methods, and then chooses the
2156    * (series of) filter(s) that give minimum compressed data size (VERY
2157    * computationally expensive).
2158    *
2159    * GRR 980525:  consider also
2160    *   (1) minimum sum of absolute differences from running average (i.e.,
2161    *       keep running sum of non-absolute differences & count of bytes)
2162    *       [track dispersion, too?  restart average if dispersion too large?]
2163    *  (1b) minimum sum of absolute differences from sliding average, probably
2164    *       with window size <= deflate window (usually 32K)
2165    *   (2) minimum sum of squared differences from zero or running average
2166    *       (i.e., ~ root-mean-square approach)
2167    */
2168
2169
2170   /* We don't need to test the 'no filter' case if this is the only filter
2171    * that has been chosen, as it doesn't actually do anything to the data.
2172    */
2173   if ((filter_to_do & PNG_FILTER_NONE) &&
2174       filter_to_do != PNG_FILTER_NONE)
2175   {
2176      png_bytep rp;
2177      png_uint_32 sum = 0;
2178      png_uint_32 i;
2179      int v;
2180
2181      for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
2182      {
2183         v = *rp;
2184         sum += (v < 128) ? v : 256 - v;
2185      }
2186
2187#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2188      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2189      {
2190         png_uint_32 sumhi, sumlo;
2191         int j;
2192         sumlo = sum & PNG_LOMASK;
2193         sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; /* Gives us some footroom */
2194
2195         /* Reduce the sum if we match any of the previous rows */
2196         for (j = 0; j < num_p_filters; j++)
2197         {
2198            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
2199            {
2200               sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2201                  PNG_WEIGHT_SHIFT;
2202               sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2203                  PNG_WEIGHT_SHIFT;
2204            }
2205         }
2206
2207         /* Factor in the cost of this filter (this is here for completeness,
2208          * but it makes no sense to have a "cost" for the NONE filter, as
2209          * it has the minimum possible computational cost - none).
2210          */
2211         sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
2212            PNG_COST_SHIFT;
2213         sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
2214            PNG_COST_SHIFT;
2215
2216         if (sumhi > PNG_HIMASK)
2217            sum = PNG_MAXSUM;
2218         else
2219            sum = (sumhi << PNG_HISHIFT) + sumlo;
2220      }
2221#endif
2222      mins = sum;
2223   }
2224
2225   /* sub filter */
2226   if (filter_to_do == PNG_FILTER_SUB)
2227   /* it's the only filter so no testing is needed */
2228   {
2229      png_bytep rp, lp, dp;
2230      png_uint_32 i;
2231      for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
2232           i++, rp++, dp++)
2233      {
2234         *dp = *rp;
2235      }
2236      for (lp = row_buf + 1; i < row_bytes;
2237         i++, rp++, lp++, dp++)
2238      {
2239         *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
2240      }
2241      best_row = png_ptr->sub_row;
2242   }
2243
2244   else if (filter_to_do & PNG_FILTER_SUB)
2245   {
2246      png_bytep rp, dp, lp;
2247      png_uint_32 sum = 0, lmins = mins;
2248      png_uint_32 i;
2249      int v;
2250
2251#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2252      /* We temporarily increase the "minimum sum" by the factor we
2253       * would reduce the sum of this filter, so that we can do the
2254       * early exit comparison without scaling the sum each time.
2255       */
2256      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2257      {
2258         int j;
2259         png_uint_32 lmhi, lmlo;
2260         lmlo = lmins & PNG_LOMASK;
2261         lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2262
2263         for (j = 0; j < num_p_filters; j++)
2264         {
2265            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
2266            {
2267               lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2268                  PNG_WEIGHT_SHIFT;
2269               lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2270                  PNG_WEIGHT_SHIFT;
2271            }
2272         }
2273
2274         lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2275            PNG_COST_SHIFT;
2276         lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2277            PNG_COST_SHIFT;
2278
2279         if (lmhi > PNG_HIMASK)
2280            lmins = PNG_MAXSUM;
2281         else
2282            lmins = (lmhi << PNG_HISHIFT) + lmlo;
2283      }
2284#endif
2285
2286      for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
2287           i++, rp++, dp++)
2288      {
2289         v = *dp = *rp;
2290
2291         sum += (v < 128) ? v : 256 - v;
2292      }
2293      for (lp = row_buf + 1; i < row_bytes;
2294         i++, rp++, lp++, dp++)
2295      {
2296         v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
2297
2298         sum += (v < 128) ? v : 256 - v;
2299
2300         if (sum > lmins)  /* We are already worse, don't continue. */
2301            break;
2302      }
2303
2304#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2305      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2306      {
2307         int j;
2308         png_uint_32 sumhi, sumlo;
2309         sumlo = sum & PNG_LOMASK;
2310         sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2311
2312         for (j = 0; j < num_p_filters; j++)
2313         {
2314            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
2315            {
2316               sumlo = (sumlo * png_ptr->inv_filter_weights[j]) >>
2317                  PNG_WEIGHT_SHIFT;
2318               sumhi = (sumhi * png_ptr->inv_filter_weights[j]) >>
2319                  PNG_WEIGHT_SHIFT;
2320            }
2321         }
2322
2323         sumlo = (sumlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2324            PNG_COST_SHIFT;
2325         sumhi = (sumhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2326            PNG_COST_SHIFT;
2327
2328         if (sumhi > PNG_HIMASK)
2329            sum = PNG_MAXSUM;
2330         else
2331            sum = (sumhi << PNG_HISHIFT) + sumlo;
2332      }
2333#endif
2334
2335      if (sum < mins)
2336      {
2337         mins = sum;
2338         best_row = png_ptr->sub_row;
2339      }
2340   }
2341
2342   /* up filter */
2343   if (filter_to_do == PNG_FILTER_UP)
2344   {
2345      png_bytep rp, dp, pp;
2346      png_uint_32 i;
2347
2348      for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
2349           pp = prev_row + 1; i < row_bytes;
2350           i++, rp++, pp++, dp++)
2351      {
2352         *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
2353      }
2354      best_row = png_ptr->up_row;
2355   }
2356
2357   else if (filter_to_do & PNG_FILTER_UP)
2358   {
2359      png_bytep rp, dp, pp;
2360      png_uint_32 sum = 0, lmins = mins;
2361      png_uint_32 i;
2362      int v;
2363
2364
2365#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2366      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2367      {
2368         int j;
2369         png_uint_32 lmhi, lmlo;
2370         lmlo = lmins & PNG_LOMASK;
2371         lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2372
2373         for (j = 0; j < num_p_filters; j++)
2374         {
2375            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
2376            {
2377               lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2378                  PNG_WEIGHT_SHIFT;
2379               lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2380                  PNG_WEIGHT_SHIFT;
2381            }
2382         }
2383
2384         lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
2385            PNG_COST_SHIFT;
2386         lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
2387            PNG_COST_SHIFT;
2388
2389         if (lmhi > PNG_HIMASK)
2390            lmins = PNG_MAXSUM;
2391         else
2392            lmins = (lmhi << PNG_HISHIFT) + lmlo;
2393      }
2394#endif
2395
2396      for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
2397           pp = prev_row + 1; i < row_bytes; i++)
2398      {
2399         v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2400
2401         sum += (v < 128) ? v : 256 - v;
2402
2403         if (sum > lmins)  /* We are already worse, don't continue. */
2404            break;
2405      }
2406
2407#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2408      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2409      {
2410         int j;
2411         png_uint_32 sumhi, sumlo;
2412         sumlo = sum & PNG_LOMASK;
2413         sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2414
2415         for (j = 0; j < num_p_filters; j++)
2416         {
2417            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
2418            {
2419               sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2420                  PNG_WEIGHT_SHIFT;
2421               sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2422                  PNG_WEIGHT_SHIFT;
2423            }
2424         }
2425
2426         sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
2427            PNG_COST_SHIFT;
2428         sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
2429            PNG_COST_SHIFT;
2430
2431         if (sumhi > PNG_HIMASK)
2432            sum = PNG_MAXSUM;
2433         else
2434            sum = (sumhi << PNG_HISHIFT) + sumlo;
2435      }
2436#endif
2437
2438      if (sum < mins)
2439      {
2440         mins = sum;
2441         best_row = png_ptr->up_row;
2442      }
2443   }
2444
2445   /* avg filter */
2446   if (filter_to_do == PNG_FILTER_AVG)
2447   {
2448      png_bytep rp, dp, pp, lp;
2449      png_uint_32 i;
2450      for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
2451           pp = prev_row + 1; i < bpp; i++)
2452      {
2453         *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
2454      }
2455      for (lp = row_buf + 1; i < row_bytes; i++)
2456      {
2457         *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
2458                 & 0xff);
2459      }
2460      best_row = png_ptr->avg_row;
2461   }
2462
2463   else if (filter_to_do & PNG_FILTER_AVG)
2464   {
2465      png_bytep rp, dp, pp, lp;
2466      png_uint_32 sum = 0, lmins = mins;
2467      png_uint_32 i;
2468      int v;
2469
2470#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2471      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2472      {
2473         int j;
2474         png_uint_32 lmhi, lmlo;
2475         lmlo = lmins & PNG_LOMASK;
2476         lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2477
2478         for (j = 0; j < num_p_filters; j++)
2479         {
2480            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_AVG)
2481            {
2482               lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2483                  PNG_WEIGHT_SHIFT;
2484               lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2485                  PNG_WEIGHT_SHIFT;
2486            }
2487         }
2488
2489         lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
2490            PNG_COST_SHIFT;
2491         lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
2492            PNG_COST_SHIFT;
2493
2494         if (lmhi > PNG_HIMASK)
2495            lmins = PNG_MAXSUM;
2496         else
2497            lmins = (lmhi << PNG_HISHIFT) + lmlo;
2498      }
2499#endif
2500
2501      for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
2502           pp = prev_row + 1; i < bpp; i++)
2503      {
2504         v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
2505
2506         sum += (v < 128) ? v : 256 - v;
2507      }
2508      for (lp = row_buf + 1; i < row_bytes; i++)
2509      {
2510         v = *dp++ =
2511          (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) & 0xff);
2512
2513         sum += (v < 128) ? v : 256 - v;
2514
2515         if (sum > lmins)  /* We are already worse, don't continue. */
2516            break;
2517      }
2518
2519#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2520      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2521      {
2522         int j;
2523         png_uint_32 sumhi, sumlo;
2524         sumlo = sum & PNG_LOMASK;
2525         sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2526
2527         for (j = 0; j < num_p_filters; j++)
2528         {
2529            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
2530            {
2531               sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2532                  PNG_WEIGHT_SHIFT;
2533               sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2534                  PNG_WEIGHT_SHIFT;
2535            }
2536         }
2537
2538         sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
2539            PNG_COST_SHIFT;
2540         sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
2541            PNG_COST_SHIFT;
2542
2543         if (sumhi > PNG_HIMASK)
2544            sum = PNG_MAXSUM;
2545         else
2546            sum = (sumhi << PNG_HISHIFT) + sumlo;
2547      }
2548#endif
2549
2550      if (sum < mins)
2551      {
2552         mins = sum;
2553         best_row = png_ptr->avg_row;
2554      }
2555   }
2556
2557   /* Paeth filter */
2558   if (filter_to_do == PNG_FILTER_PAETH)
2559   {
2560      png_bytep rp, dp, pp, cp, lp;
2561      png_uint_32 i;
2562      for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
2563           pp = prev_row + 1; i < bpp; i++)
2564      {
2565         *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2566      }
2567
2568      for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
2569      {
2570         int a, b, c, pa, pb, pc, p;
2571
2572         b = *pp++;
2573         c = *cp++;
2574         a = *lp++;
2575
2576         p = b - c;
2577         pc = a - c;
2578
2579#ifdef PNG_USE_ABS
2580         pa = abs(p);
2581         pb = abs(pc);
2582         pc = abs(p + pc);
2583#else
2584         pa = p < 0 ? -p : p;
2585         pb = pc < 0 ? -pc : pc;
2586         pc = (p + pc) < 0 ? -(p + pc) : p + pc;
2587#endif
2588
2589         p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
2590
2591         *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
2592      }
2593      best_row = png_ptr->paeth_row;
2594   }
2595
2596   else if (filter_to_do & PNG_FILTER_PAETH)
2597   {
2598      png_bytep rp, dp, pp, cp, lp;
2599      png_uint_32 sum = 0, lmins = mins;
2600      png_uint_32 i;
2601      int v;
2602
2603#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2604      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2605      {
2606         int j;
2607         png_uint_32 lmhi, lmlo;
2608         lmlo = lmins & PNG_LOMASK;
2609         lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2610
2611         for (j = 0; j < num_p_filters; j++)
2612         {
2613            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
2614            {
2615               lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2616                  PNG_WEIGHT_SHIFT;
2617               lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2618                  PNG_WEIGHT_SHIFT;
2619            }
2620         }
2621
2622         lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2623            PNG_COST_SHIFT;
2624         lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2625            PNG_COST_SHIFT;
2626
2627         if (lmhi > PNG_HIMASK)
2628            lmins = PNG_MAXSUM;
2629         else
2630            lmins = (lmhi << PNG_HISHIFT) + lmlo;
2631      }
2632#endif
2633
2634      for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
2635           pp = prev_row + 1; i < bpp; i++)
2636      {
2637         v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2638
2639         sum += (v < 128) ? v : 256 - v;
2640      }
2641
2642      for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
2643      {
2644         int a, b, c, pa, pb, pc, p;
2645
2646         b = *pp++;
2647         c = *cp++;
2648         a = *lp++;
2649
2650#ifndef PNG_SLOW_PAETH
2651         p = b - c;
2652         pc = a - c;
2653#ifdef PNG_USE_ABS
2654         pa = abs(p);
2655         pb = abs(pc);
2656         pc = abs(p + pc);
2657#else
2658         pa = p < 0 ? -p : p;
2659         pb = pc < 0 ? -pc : pc;
2660         pc = (p + pc) < 0 ? -(p + pc) : p + pc;
2661#endif
2662         p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
2663#else /* PNG_SLOW_PAETH */
2664         p = a + b - c;
2665         pa = abs(p - a);
2666         pb = abs(p - b);
2667         pc = abs(p - c);
2668         if (pa <= pb && pa <= pc)
2669            p = a;
2670         else if (pb <= pc)
2671            p = b;
2672         else
2673            p = c;
2674#endif /* PNG_SLOW_PAETH */
2675
2676         v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
2677
2678         sum += (v < 128) ? v : 256 - v;
2679
2680         if (sum > lmins)  /* We are already worse, don't continue. */
2681            break;
2682      }
2683
2684#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2685      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2686      {
2687         int j;
2688         png_uint_32 sumhi, sumlo;
2689         sumlo = sum & PNG_LOMASK;
2690         sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2691
2692         for (j = 0; j < num_p_filters; j++)
2693         {
2694            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
2695            {
2696               sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2697                  PNG_WEIGHT_SHIFT;
2698               sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2699                  PNG_WEIGHT_SHIFT;
2700            }
2701         }
2702
2703         sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2704            PNG_COST_SHIFT;
2705         sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2706            PNG_COST_SHIFT;
2707
2708         if (sumhi > PNG_HIMASK)
2709            sum = PNG_MAXSUM;
2710         else
2711            sum = (sumhi << PNG_HISHIFT) + sumlo;
2712      }
2713#endif
2714
2715      if (sum < mins)
2716      {
2717         best_row = png_ptr->paeth_row;
2718      }
2719   }
2720#endif /* PNG_NO_WRITE_FILTER */
2721   /* Do the actual writing of the filtered row data from the chosen filter. */
2722
2723   png_write_filtered_row(png_ptr, best_row);
2724
2725#ifndef PNG_NO_WRITE_FILTER
2726#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2727   /* Save the type of filter we picked this time for future calculations */
2728   if (png_ptr->num_prev_filters > 0)
2729   {
2730      int j;
2731      for (j = 1; j < num_p_filters; j++)
2732      {
2733         png_ptr->prev_filters[j] = png_ptr->prev_filters[j - 1];
2734      }
2735      png_ptr->prev_filters[j] = best_row[0];
2736   }
2737#endif
2738#endif /* PNG_NO_WRITE_FILTER */
2739}
2740
2741
2742/* Do the actual writing of a previously filtered row. */
2743void /* PRIVATE */
2744png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row)
2745{
2746   png_debug(1, "in png_write_filtered_row\n");
2747   png_debug1(2, "filter = %d\n", filtered_row[0]);
2748   /* set up the zlib input buffer */
2749
2750   png_ptr->zstream.next_in = filtered_row;
2751   png_ptr->zstream.avail_in = (uInt)png_ptr->row_info.rowbytes + 1;
2752   /* repeat until we have compressed all the data */
2753   do
2754   {
2755      int ret; /* return of zlib */
2756
2757      /* compress the data */
2758      ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
2759      /* check for compression errors */
2760      if (ret != Z_OK)
2761      {
2762         if (png_ptr->zstream.msg != NULL)
2763            png_error(png_ptr, png_ptr->zstream.msg);
2764         else
2765            png_error(png_ptr, "zlib error");
2766      }
2767
2768      /* see if it is time to write another IDAT */
2769      if (!(png_ptr->zstream.avail_out))
2770      {
2771         /* write the IDAT and reset the zlib output buffer */
2772         png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
2773         png_ptr->zstream.next_out = png_ptr->zbuf;
2774         png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
2775      }
2776   /* repeat until all data has been compressed */
2777   } while (png_ptr->zstream.avail_in);
2778
2779   /* swap the current and previous rows */
2780   if (png_ptr->prev_row != NULL)
2781   {
2782      png_bytep tptr;
2783
2784      tptr = png_ptr->prev_row;
2785      png_ptr->prev_row = png_ptr->row_buf;
2786      png_ptr->row_buf = tptr;
2787   }
2788
2789   /* finish row - updates counters and flushes zlib if last row */
2790   png_write_finish_row(png_ptr);
2791
2792#if defined(PNG_WRITE_FLUSH_SUPPORTED)
2793   png_ptr->flush_rows++;
2794
2795   if (png_ptr->flush_dist > 0 &&
2796       png_ptr->flush_rows >= png_ptr->flush_dist)
2797   {
2798      png_write_flush(png_ptr);
2799   }
2800#endif
2801}
2802#endif /* PNG_WRITE_SUPPORTED */
2803