core/libs/libpng-1.2.18/pngwutil.c

   1
   2 /* pngwutil.c - utilities to write a PNG file
   3  *
   4  * Last changed in libpng 1.2.15 January 5, 2007
   5  * For conditions of distribution and use, see copyright notice in png.h
   6  * Copyright (c) 1998-2007 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  */
  19 void PNGAPI
  20 png_save_uint_32(png_bytep buf, png_uint_32 i)
  21 {
  22    buf[0] = (png_byte)((i >> 24) & 0xff);
  23    buf[1] = (png_byte)((i >> 16) & 0xff);
  24    buf[2] = (png_byte)((i >> 8) & 0xff);
  25    buf[3] = (png_byte)(i & 0xff);
  26 }
  27
  28 /* The png_save_int_32 function assumes integers are stored in two's
  29  * complement format.  If this isn't the case, then this routine needs to
  30  * be modified to write data in two's complement format.
  31  */
  32 void PNGAPI
  33 png_save_int_32(png_bytep buf, png_int_32 i)
  34 {
  35    buf[0] = (png_byte)((i >> 24) & 0xff);
  36    buf[1] = (png_byte)((i >> 16) & 0xff);
  37    buf[2] = (png_byte)((i >> 8) & 0xff);
  38    buf[3] = (png_byte)(i & 0xff);
  39 }
  40
  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  */
  45 void PNGAPI
  46 png_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  */
  61 void PNGAPI
  62 png_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  */
  75 void PNGAPI
  76 png_write_chunk_start(png_structp png_ptr, png_bytep chunk_name,
  77    png_uint_32 length)
  78 {
  79    png_byte buf[4];
  80    png_debug2(0, "Writing %s chunk (%lu bytes)\n", chunk_name, length);
  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  */
  99 void PNGAPI
 100 png_write_chunk_data(png_structp png_ptr, png_bytep data, png_size_t length)
 101 {
 102    /* write the data, and run the CRC over it */
 103    if(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(). */
 112 void PNGAPI
 113 png_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  */
 131 void /* PRIVATE */
 132 png_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
 150 typedef 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 */
 160 static int /* PRIVATE */
 161 png_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       sprintf(msg, "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 */
 336 static void /* PRIVATE */
 337 png_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  */
 375 void /* PRIVATE */
 376 png_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    png_byte buf[13]; /* buffer to store the IHDR info */
 384
 385    png_debug(1, "in png_write_IHDR\n");
 386    /* Check that we have valid input data from the application info */
 387    switch (color_type)
 388    {
 389       case PNG_COLOR_TYPE_GRAY:
 390          switch (bit_depth)
 391          {
 392             case 1:
 393             case 2:
 394             case 4:
 395             case 8:
 396             case 16: png_ptr->channels = 1; break;
 397             default: png_error(png_ptr,"Invalid bit depth for grayscale image");
 398          }
 399          break;
 400       case PNG_COLOR_TYPE_RGB:
 401          if (bit_depth != 8 && bit_depth != 16)
 402             png_error(png_ptr, "Invalid bit depth for RGB image");
 403          png_ptr->channels = 3;
 404          break;
 405       case PNG_COLOR_TYPE_PALETTE:
 406          switch (bit_depth)
 407          {
 408             case 1:
 409             case 2:
 410             case 4:
 411             case 8: png_ptr->channels = 1; break;
 412             default: png_error(png_ptr, "Invalid bit depth for paletted image");
 413          }
 414          break;
 415       case PNG_COLOR_TYPE_GRAY_ALPHA:
 416          if (bit_depth != 8 && bit_depth != 16)
 417             png_error(png_ptr, "Invalid bit depth for grayscale+alpha image");
 418          png_ptr->channels = 2;
 419          break;
 420       case PNG_COLOR_TYPE_RGB_ALPHA:
 421          if (bit_depth != 8 && bit_depth != 16)
 422             png_error(png_ptr, "Invalid bit depth for RGBA image");
 423          png_ptr->channels = 4;
 424          break;
 425       default:
 426          png_error(png_ptr, "Invalid image color type specified");
 427    }
 428
 429    if (compression_type != PNG_COMPRESSION_TYPE_BASE)
 430    {
 431       png_warning(png_ptr, "Invalid compression type specified");
 432       compression_type = PNG_COMPRESSION_TYPE_BASE;
 433    }
 434
 435    /* Write filter_method 64 (intrapixel differencing) only if
 436     * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
 437     * 2. Libpng did not write a PNG signature (this filter_method is only
 438     *    used in PNG datastreams that are embedded in MNG datastreams) and
 439     * 3. The application called png_permit_mng_features with a mask that
 440     *    included PNG_FLAG_MNG_FILTER_64 and
 441     * 4. The filter_method is 64 and
 442     * 5. The color_type is RGB or RGBA
 443     */
 444    if (
 445 #if defined(PNG_MNG_FEATURES_SUPPORTED)
 446       !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
 447       ((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE) == 0) &&
 448       (color_type == PNG_COLOR_TYPE_RGB ||
 449        color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&
 450       (filter_type == PNG_INTRAPIXEL_DIFFERENCING)) &&
 451 #endif
 452       filter_type != PNG_FILTER_TYPE_BASE)
 453    {
 454       png_warning(png_ptr, "Invalid filter type specified");
 455       filter_type = PNG_FILTER_TYPE_BASE;
 456    }
 457
 458 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
 459    if (interlace_type != PNG_INTERLACE_NONE &&
 460       interlace_type != PNG_INTERLACE_ADAM7)
 461    {
 462       png_warning(png_ptr, "Invalid interlace type specified");
 463       interlace_type = PNG_INTERLACE_ADAM7;
 464    }
 465 #else
 466    interlace_type=PNG_INTERLACE_NONE;
 467 #endif
 468
 469    /* save off the relevent information */
 470    png_ptr->bit_depth = (png_byte)bit_depth;
 471    png_ptr->color_type = (png_byte)color_type;
 472    png_ptr->interlaced = (png_byte)interlace_type;
 473 #if defined(PNG_MNG_FEATURES_SUPPORTED)
 474    png_ptr->filter_type = (png_byte)filter_type;
 475 #endif
 476    png_ptr->compression_type = (png_byte)compression_type;
 477    png_ptr->width = width;
 478    png_ptr->height = height;
 479
 480    png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels);
 481    png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width);
 482    /* set the usr info, so any transformations can modify it */
 483    png_ptr->usr_width = png_ptr->width;
 484    png_ptr->usr_bit_depth = png_ptr->bit_depth;
 485    png_ptr->usr_channels = png_ptr->channels;
 486
 487    /* pack the header information into the buffer */
 488    png_save_uint_32(buf, width);
 489    png_save_uint_32(buf + 4, height);
 490    buf[8] = (png_byte)bit_depth;
 491    buf[9] = (png_byte)color_type;
 492    buf[10] = (png_byte)compression_type;
 493    buf[11] = (png_byte)filter_type;
 494    buf[12] = (png_byte)interlace_type;
 495
 496    /* write the chunk */
 497    png_write_chunk(png_ptr, (png_bytep)png_IHDR, buf, (png_size_t)13);
 498
 499    /* initialize zlib with PNG info */
 500    png_ptr->zstream.zalloc = png_zalloc;
 501    png_ptr->zstream.zfree = png_zfree;
 502    png_ptr->zstream.opaque = (voidpf)png_ptr;
 503    if (!(png_ptr->do_filter))
 504    {
 505       if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
 506          png_ptr->bit_depth < 8)
 507          png_ptr->do_filter = PNG_FILTER_NONE;
 508       else
 509          png_ptr->do_filter = PNG_ALL_FILTERS;
 510    }
 511    if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY))
 512    {
 513       if (png_ptr->do_filter != PNG_FILTER_NONE)
 514          png_ptr->zlib_strategy = Z_FILTERED;
 515       else
 516          png_ptr->zlib_strategy = Z_DEFAULT_STRATEGY;
 517    }
 518    if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_LEVEL))
 519       png_ptr->zlib_level = Z_DEFAULT_COMPRESSION;
 520    if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL))
 521       png_ptr->zlib_mem_level = 8;
 522    if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS))
 523       png_ptr->zlib_window_bits = 15;
 524    if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_METHOD))
 525       png_ptr->zlib_method = 8;
 526    if (deflateInit2(&png_ptr->zstream, png_ptr->zlib_level,
 527       png_ptr->zlib_method, png_ptr->zlib_window_bits,
 528       png_ptr->zlib_mem_level, png_ptr->zlib_strategy) != Z_OK)
 529        png_error(png_ptr, "zlib failed to initialize compressor");
 530    png_ptr->zstream.next_out = png_ptr->zbuf;
 531    png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
 532    /* libpng is not interested in zstream.data_type */
 533    /* set it to a predefined value, to avoid its evaluation inside zlib */
 534    png_ptr->zstream.data_type = Z_BINARY;
 535
 536    png_ptr->mode = PNG_HAVE_IHDR;
 537 }
 538
 539 /* write the palette.  We are careful not to trust png_color to be in the
 540  * correct order for PNG, so people can redefine it to any convenient
 541  * structure.
 542  */
 543 void /* PRIVATE */
 544 png_write_PLTE(png_structp png_ptr, png_colorp palette, png_uint_32 num_pal)
 545 {
 546 #ifdef PNG_USE_LOCAL_ARRAYS
 547    PNG_PLTE;
 548 #endif
 549    png_uint_32 i;
 550    png_colorp pal_ptr;
 551    png_byte buf[3];
 552
 553    png_debug(1, "in png_write_PLTE\n");
 554    if ((
 555 #if defined(PNG_MNG_FEATURES_SUPPORTED)
 556         !(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) &&
 557 #endif
 558         num_pal == 0) || num_pal > 256)
 559    {
 560      if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
 561      {
 562         png_error(png_ptr, "Invalid number of colors in palette");
 563      }
 564      else
 565      {
 566         png_warning(png_ptr, "Invalid number of colors in palette");
 567         return;
 568      }
 569    }
 570
 571    if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))
 572    {
 573       png_warning(png_ptr,
 574         "Ignoring request to write a PLTE chunk in grayscale PNG");
 575       return;
 576    }
 577
 578    png_ptr->num_palette = (png_uint_16)num_pal;
 579    png_debug1(3, "num_palette = %d\n", png_ptr->num_palette);
 580
 581    png_write_chunk_start(png_ptr, (png_bytep)png_PLTE, num_pal * 3);
 582 #ifndef PNG_NO_POINTER_INDEXING
 583    for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++)
 584    {
 585       buf[0] = pal_ptr->red;
 586       buf[1] = pal_ptr->green;
 587       buf[2] = pal_ptr->blue;
 588       png_write_chunk_data(png_ptr, buf, (png_size_t)3);
 589    }
 590 #else
 591    /* This is a little slower but some buggy compilers need to do this instead */
 592    pal_ptr=palette;
 593    for (i = 0; i < num_pal; i++)
 594    {
 595       buf[0] = pal_ptr[i].red;
 596       buf[1] = pal_ptr[i].green;
 597       buf[2] = pal_ptr[i].blue;
 598       png_write_chunk_data(png_ptr, buf, (png_size_t)3);
 599    }
 600 #endif
 601    png_write_chunk_end(png_ptr);
 602    png_ptr->mode |= PNG_HAVE_PLTE;
 603 }
 604
 605 /* write an IDAT chunk */
 606 void /* PRIVATE */
 607 png_write_IDAT(png_structp png_ptr, png_bytep data, png_size_t length)
 608 {
 609 #ifdef PNG_USE_LOCAL_ARRAYS
 610    PNG_IDAT;
 611 #endif
 612    png_debug(1, "in png_write_IDAT\n");
 613
 614    /* Optimize the CMF field in the zlib stream. */
 615    /* This hack of the zlib stream is compliant to the stream specification. */
 616    if (!(png_ptr->mode & PNG_HAVE_IDAT) &&
 617        png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
 618    {
 619       unsigned int z_cmf = data[0];  /* zlib compression method and flags */
 620       if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
 621       {
 622          /* Avoid memory underflows and multiplication overflows. */
 623          /* The conditions below are practically always satisfied;
 624             however, they still must be checked. */
 625          if (length >= 2 &&
 626              png_ptr->height < 16384 && png_ptr->width < 16384)
 627          {
 628             png_uint_32 uncompressed_idat_size = png_ptr->height *
 629                ((png_ptr->width *
 630                png_ptr->channels * png_ptr->bit_depth + 15) >> 3);
 631             unsigned int z_cinfo = z_cmf >> 4;
 632             unsigned int half_z_window_size = 1 << (z_cinfo + 7);
 633             while (uncompressed_idat_size <= half_z_window_size &&
 634                    half_z_window_size >= 256)
 635             {
 636                z_cinfo--;
 637                half_z_window_size >>= 1;
 638             }
 639             z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
 640             if (data[0] != (png_byte)z_cmf)
 641             {
 642                data[0] = (png_byte)z_cmf;
 643                data[1] &= 0xe0;
 644                data[1] += (png_byte)(0x1f - ((z_cmf << 8) + data[1]) % 0x1f);
 645             }
 646          }
 647       }
 648       else
 649          png_error(png_ptr,
 650             "Invalid zlib compression method or flags in IDAT");
 651    }
 652
 653    png_write_chunk(png_ptr, (png_bytep)png_IDAT, data, length);
 654    png_ptr->mode |= PNG_HAVE_IDAT;
 655 }
 656
 657 /* write an IEND chunk */
 658 void /* PRIVATE */
 659 png_write_IEND(png_structp png_ptr)
 660 {
 661 #ifdef PNG_USE_LOCAL_ARRAYS
 662    PNG_IEND;
 663 #endif
 664    png_debug(1, "in png_write_IEND\n");
 665    png_write_chunk(png_ptr, (png_bytep)png_IEND, png_bytep_NULL,
 666      (png_size_t)0);
 667    png_ptr->mode |= PNG_HAVE_IEND;
 668 }
 669
 670 #if defined(PNG_WRITE_gAMA_SUPPORTED)
 671 /* write a gAMA chunk */
 672 #ifdef PNG_FLOATING_POINT_SUPPORTED
 673 void /* PRIVATE */
 674 png_write_gAMA(png_structp png_ptr, double file_gamma)
 675 {
 676 #ifdef PNG_USE_LOCAL_ARRAYS
 677    PNG_gAMA;
 678 #endif
 679    png_uint_32 igamma;
 680    png_byte buf[4];
 681
 682    png_debug(1, "in png_write_gAMA\n");
 683    /* file_gamma is saved in 1/100,000ths */
 684    igamma = (png_uint_32)(file_gamma * 100000.0 + 0.5);
 685    png_save_uint_32(buf, igamma);
 686    png_write_chunk(png_ptr, (png_bytep)png_gAMA, buf, (png_size_t)4);
 687 }
 688 #endif
 689 #ifdef PNG_FIXED_POINT_SUPPORTED
 690 void /* PRIVATE */
 691 png_write_gAMA_fixed(png_structp png_ptr, png_fixed_point file_gamma)
 692 {
 693 #ifdef PNG_USE_LOCAL_ARRAYS
 694    PNG_gAMA;
 695 #endif
 696    png_byte buf[4];
 697
 698    png_debug(1, "in png_write_gAMA\n");
 699    /* file_gamma is saved in 1/100,000ths */
 700    png_save_uint_32(buf, (png_uint_32)file_gamma);
 701    png_write_chunk(png_ptr, (png_bytep)png_gAMA, buf, (png_size_t)4);
 702 }
 703 #endif
 704 #endif
 705
 706 #if defined(PNG_WRITE_sRGB_SUPPORTED)
 707 /* write a sRGB chunk */
 708 void /* PRIVATE */
 709 png_write_sRGB(png_structp png_ptr, int srgb_intent)
 710 {
 711 #ifdef PNG_USE_LOCAL_ARRAYS
 712    PNG_sRGB;
 713 #endif
 714    png_byte buf[1];
 715
 716    png_debug(1, "in png_write_sRGB\n");
 717    if(srgb_intent >= PNG_sRGB_INTENT_LAST)
 718          png_warning(png_ptr,
 719             "Invalid sRGB rendering intent specified");
 720    buf[0]=(png_byte)srgb_intent;
 721    png_write_chunk(png_ptr, (png_bytep)png_sRGB, buf, (png_size_t)1);
 722 }
 723 #endif
 724
 725 #if defined(PNG_WRITE_iCCP_SUPPORTED)
 726 /* write an iCCP chunk */
 727 void /* PRIVATE */
 728 png_write_iCCP(png_structp png_ptr, png_charp name, int compression_type,
 729    png_charp profile, int profile_len)
 730 {
 731 #ifdef PNG_USE_LOCAL_ARRAYS
 732    PNG_iCCP;
 733 #endif
 734    png_size_t name_len;
 735    png_charp new_name;
 736    compression_state comp;
 737    int embedded_profile_len = 0;
 738
 739    png_debug(1, "in png_write_iCCP\n");
 740
 741    comp.num_output_ptr = 0;
 742    comp.max_output_ptr = 0;
 743    comp.output_ptr = NULL;
 744    comp.input = NULL;
 745    comp.input_len = 0;
 746
 747    if (name == NULL || (name_len = png_check_keyword(png_ptr, name,
 748       &new_name)) == 0)
 749    {
 750       png_warning(png_ptr, "Empty keyword in iCCP chunk");
 751       return;
 752    }
 753
 754    if (compression_type != PNG_COMPRESSION_TYPE_BASE)
 755       png_warning(png_ptr, "Unknown compression type in iCCP chunk");
 756
 757    if (profile == NULL)
 758       profile_len = 0;
 759
 760    if (profile_len > 3)
 761       embedded_profile_len =
 762           ((*( (png_bytep)profile  ))<<24) |
 763           ((*( (png_bytep)profile+1))<<16) |
 764           ((*( (png_bytep)profile+2))<< 8) |
 765           ((*( (png_bytep)profile+3))    );
 766
 767    if (profile_len < embedded_profile_len)
 768      {
 769         png_warning(png_ptr,
 770           "Embedded profile length too large in iCCP chunk");
 771         return;
 772      }
 773
 774    if (profile_len > embedded_profile_len)
 775      {
 776         png_warning(png_ptr,
 777           "Truncating profile to actual length in iCCP chunk");
 778         profile_len = embedded_profile_len;
 779      }
 780
 781    if (profile_len)
 782        profile_len = png_text_compress(png_ptr, profile, (png_size_t)profile_len,
 783           PNG_COMPRESSION_TYPE_BASE, &comp);
 784
 785    /* make sure we include the NULL after the name and the compression type */
 786    png_write_chunk_start(png_ptr, (png_bytep)png_iCCP,
 787           (png_uint_32)name_len+profile_len+2);
 788    new_name[name_len+1]=0x00;
 789    png_write_chunk_data(png_ptr, (png_bytep)new_name, name_len + 2);
 790
 791    if (profile_len)
 792       png_write_compressed_data_out(png_ptr, &comp);
 793
 794    png_write_chunk_end(png_ptr);
 795    png_free(png_ptr, new_name);
 796 }
 797 #endif
 798
 799 #if defined(PNG_WRITE_sPLT_SUPPORTED)
 800 /* write a sPLT chunk */
 801 void /* PRIVATE */
 802 png_write_sPLT(png_structp png_ptr, png_sPLT_tp spalette)
 803 {
 804 #ifdef PNG_USE_LOCAL_ARRAYS
 805    PNG_sPLT;
 806 #endif
 807    png_size_t name_len;
 808    png_charp new_name;
 809    png_byte entrybuf[10];
 810    int entry_size = (spalette->depth == 8 ? 6 : 10);
 811    int palette_size = entry_size * spalette->nentries;
 812    png_sPLT_entryp ep;
 813 #ifdef PNG_NO_POINTER_INDEXING
 814    int i;
 815 #endif
 816
 817    png_debug(1, "in png_write_sPLT\n");
 818    if (spalette->name == NULL || (name_len = png_check_keyword(png_ptr,
 819       spalette->name, &new_name))==0)
 820    {
 821       png_warning(png_ptr, "Empty keyword in sPLT chunk");
 822       return;
 823    }
 824
 825    /* make sure we include the NULL after the name */
 826    png_write_chunk_start(png_ptr, (png_bytep)png_sPLT,
 827           (png_uint_32)(name_len + 2 + palette_size));
 828    png_write_chunk_data(png_ptr, (png_bytep)new_name, name_len + 1);
 829    png_write_chunk_data(png_ptr, (png_bytep)&spalette->depth, 1);
 830
 831    /* loop through each palette entry, writing appropriately */
 832 #ifndef PNG_NO_POINTER_INDEXING
 833    for (ep = spalette->entries; ep<spalette->entries+spalette->nentries; ep++)
 834    {
 835        if (spalette->depth == 8)
 836        {
 837            entrybuf[0] = (png_byte)ep->red;
 838            entrybuf[1] = (png_byte)ep->green;
 839            entrybuf[2] = (png_byte)ep->blue;
 840            entrybuf[3] = (png_byte)ep->alpha;
 841            png_save_uint_16(entrybuf + 4, ep->frequency);
 842        }
 843        else
 844        {
 845            png_save_uint_16(entrybuf + 0, ep->red);
 846            png_save_uint_16(entrybuf + 2, ep->green);
 847            png_save_uint_16(entrybuf + 4, ep->blue);
 848            png_save_uint_16(entrybuf + 6, ep->alpha);
 849            png_save_uint_16(entrybuf + 8, ep->frequency);
 850        }
 851        png_write_chunk_data(png_ptr, entrybuf, (png_size_t)entry_size);
 852    }
 853 #else
 854    ep=spalette->entries;
 855    for (i=0; i>spalette->nentries; i++)
 856    {
 857        if (spalette->depth == 8)
 858        {
 859            entrybuf[0] = (png_byte)ep[i].red;
 860            entrybuf[1] = (png_byte)ep[i].green;
 861            entrybuf[2] = (png_byte)ep[i].blue;
 862            entrybuf[3] = (png_byte)ep[i].alpha;
 863            png_save_uint_16(entrybuf + 4, ep[i].frequency);
 864        }
 865        else
 866        {
 867            png_save_uint_16(entrybuf + 0, ep[i].red);
 868            png_save_uint_16(entrybuf + 2, ep[i].green);
 869            png_save_uint_16(entrybuf + 4, ep[i].blue);
 870            png_save_uint_16(entrybuf + 6, ep[i].alpha);
 871            png_save_uint_16(entrybuf + 8, ep[i].frequency);
 872        }
 873        png_write_chunk_data(png_ptr, entrybuf, entry_size);
 874    }
 875 #endif
 876
 877    png_write_chunk_end(png_ptr);
 878    png_free(png_ptr, new_name);
 879 }
 880 #endif
 881
 882 #if defined(PNG_WRITE_sBIT_SUPPORTED)
 883 /* write the sBIT chunk */
 884 void /* PRIVATE */
 885 png_write_sBIT(png_structp png_ptr, png_color_8p sbit, int color_type)
 886 {
 887 #ifdef PNG_USE_LOCAL_ARRAYS
 888    PNG_sBIT;
 889 #endif
 890    png_byte buf[4];
 891    png_size_t size;
 892
 893    png_debug(1, "in png_write_sBIT\n");
 894    /* make sure we don't depend upon the order of PNG_COLOR_8 */
 895    if (color_type & PNG_COLOR_MASK_COLOR)
 896    {
 897       png_byte maxbits;
 898
 899       maxbits = (png_byte)(color_type==PNG_COLOR_TYPE_PALETTE ? 8 :
 900                 png_ptr->usr_bit_depth);
 901       if (sbit->red == 0 || sbit->red > maxbits ||
 902           sbit->green == 0 || sbit->green > maxbits ||
 903           sbit->blue == 0 || sbit->blue > maxbits)
 904       {
 905          png_warning(png_ptr, "Invalid sBIT depth specified");
 906          return;
 907       }
 908       buf[0] = sbit->red;
 909       buf[1] = sbit->green;
 910       buf[2] = sbit->blue;
 911       size = 3;
 912    }
 913    else
 914    {
 915       if (sbit->gray == 0 || sbit->gray > png_ptr->usr_bit_depth)
 916       {
 917          png_warning(png_ptr, "Invalid sBIT depth specified");
 918          return;
 919       }
 920       buf[0] = sbit->gray;
 921       size = 1;
 922    }
 923
 924    if (color_type & PNG_COLOR_MASK_ALPHA)
 925    {
 926       if (sbit->alpha == 0 || sbit->alpha > png_ptr->usr_bit_depth)
 927       {
 928          png_warning(png_ptr, "Invalid sBIT depth specified");
 929          return;
 930       }
 931       buf[size++] = sbit->alpha;
 932    }
 933
 934    png_write_chunk(png_ptr, (png_bytep)png_sBIT, buf, size);
 935 }
 936 #endif
 937
 938 #if defined(PNG_WRITE_cHRM_SUPPORTED)
 939 /* write the cHRM chunk */
 940 #ifdef PNG_FLOATING_POINT_SUPPORTED
 941 void /* PRIVATE */
 942 png_write_cHRM(png_structp png_ptr, double white_x, double white_y,
 943    double red_x, double red_y, double green_x, double green_y,
 944    double blue_x, double blue_y)
 945 {
 946 #ifdef PNG_USE_LOCAL_ARRAYS
 947    PNG_cHRM;
 948 #endif
 949    png_byte buf[32];
 950    png_uint_32 itemp;
 951
 952    png_debug(1, "in png_write_cHRM\n");
 953    /* each value is saved in 1/100,000ths */
 954    if (white_x < 0 || white_x > 0.8 || white_y < 0 || white_y > 0.8 ||
 955        white_x + white_y > 1.0)
 956    {
 957       png_warning(png_ptr, "Invalid cHRM white point specified");
 958 #if !defined(PNG_NO_CONSOLE_IO)
 959       fprintf(stderr,"white_x=%f, white_y=%f\n",white_x, white_y);
 960 #endif
 961       return;
 962    }
 963    itemp = (png_uint_32)(white_x * 100000.0 + 0.5);
 964    png_save_uint_32(buf, itemp);
 965    itemp = (png_uint_32)(white_y * 100000.0 + 0.5);
 966    png_save_uint_32(buf + 4, itemp);
 967
 968    if (red_x < 0 ||  red_y < 0 || red_x + red_y > 1.0)
 969    {
 970       png_warning(png_ptr, "Invalid cHRM red point specified");
 971       return;
 972    }
 973    itemp = (png_uint_32)(red_x * 100000.0 + 0.5);
 974    png_save_uint_32(buf + 8, itemp);
 975    itemp = (png_uint_32)(red_y * 100000.0 + 0.5);
 976    png_save_uint_32(buf + 12, itemp);
 977
 978    if (green_x < 0 || green_y < 0 || green_x + green_y > 1.0)
 979    {
 980       png_warning(png_ptr, "Invalid cHRM green point specified");
 981       return;
 982    }
 983    itemp = (png_uint_32)(green_x * 100000.0 + 0.5);
 984    png_save_uint_32(buf + 16, itemp);
 985    itemp = (png_uint_32)(green_y * 100000.0 + 0.5);
 986    png_save_uint_32(buf + 20, itemp);
 987
 988    if (blue_x < 0 || blue_y < 0 || blue_x + blue_y > 1.0)
 989    {
 990       png_warning(png_ptr, "Invalid cHRM blue point specified");
 991       return;
 992    }
 993    itemp = (png_uint_32)(blue_x * 100000.0 + 0.5);
 994    png_save_uint_32(buf + 24, itemp);
 995    itemp = (png_uint_32)(blue_y * 100000.0 + 0.5);
 996    png_save_uint_32(buf + 28, itemp);
 997
 998    png_write_chunk(png_ptr, (png_bytep)png_cHRM, buf, (png_size_t)32);
 999 }
1000 #endif
1001 #ifdef PNG_FIXED_POINT_SUPPORTED
1002 void /* PRIVATE */
1003 png_write_cHRM_fixed(png_structp png_ptr, png_fixed_point white_x,
1004    png_fixed_point white_y, png_fixed_point red_x, png_fixed_point red_y,
1005    png_fixed_point green_x, png_fixed_point green_y, png_fixed_point blue_x,
1006    png_fixed_point blue_y)
1007 {
1008 #ifdef PNG_USE_LOCAL_ARRAYS
1009    PNG_cHRM;
1010 #endif
1011    png_byte buf[32];
1012
1013    png_debug(1, "in png_write_cHRM\n");
1014    /* each value is saved in 1/100,000ths */
1015    if (white_x > 80000L || white_y > 80000L || white_x + white_y > 100000L)
1016    {
1017       png_warning(png_ptr, "Invalid fixed cHRM white point specified");
1018 #if !defined(PNG_NO_CONSOLE_IO)
1019       fprintf(stderr,"white_x=%ld, white_y=%ld\n",white_x, white_y);
1020 #endif
1021       return;
1022    }
1023    png_save_uint_32(buf, (png_uint_32)white_x);
1024    png_save_uint_32(buf + 4, (png_uint_32)white_y);
1025
1026    if (red_x + red_y > 100000L)
1027    {
1028       png_warning(png_ptr, "Invalid cHRM fixed red point specified");
1029       return;
1030    }
1031    png_save_uint_32(buf + 8, (png_uint_32)red_x);
1032    png_save_uint_32(buf + 12, (png_uint_32)red_y);
1033
1034    if (green_x + green_y > 100000L)
1035    {
1036       png_warning(png_ptr, "Invalid fixed cHRM green point specified");
1037       return;
1038    }
1039    png_save_uint_32(buf + 16, (png_uint_32)green_x);
1040    png_save_uint_32(buf + 20, (png_uint_32)green_y);
1041
1042    if (blue_x + blue_y > 100000L)
1043    {
1044       png_warning(png_ptr, "Invalid fixed cHRM blue point specified");
1045       return;
1046    }
1047    png_save_uint_32(buf + 24, (png_uint_32)blue_x);
1048    png_save_uint_32(buf + 28, (png_uint_32)blue_y);
1049
1050    png_write_chunk(png_ptr, (png_bytep)png_cHRM, buf, (png_size_t)32);
1051 }
1052 #endif
1053 #endif
1054
1055 #if defined(PNG_WRITE_tRNS_SUPPORTED)
1056 /* write the tRNS chunk */
1057 void /* PRIVATE */
1058 png_write_tRNS(png_structp png_ptr, png_bytep trans, png_color_16p tran,
1059    int num_trans, int color_type)
1060 {
1061 #ifdef PNG_USE_LOCAL_ARRAYS
1062    PNG_tRNS;
1063 #endif
1064    png_byte buf[6];
1065
1066    png_debug(1, "in png_write_tRNS\n");
1067    if (color_type == PNG_COLOR_TYPE_PALETTE)
1068    {
1069       if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette)
1070       {
1071          png_warning(png_ptr,"Invalid number of transparent colors specified");
1072          return;
1073       }
1074       /* write the chunk out as it is */
1075       png_write_chunk(png_ptr, (png_bytep)png_tRNS, trans, (png_size_t)num_trans);
1076    }
1077    else if (color_type == PNG_COLOR_TYPE_GRAY)
1078    {
1079       /* one 16 bit value */
1080       if(tran->gray >= (1 << png_ptr->bit_depth))
1081       {
1082          png_warning(png_ptr,
1083            "Ignoring attempt to write tRNS chunk out-of-range for bit_depth");
1084          return;
1085       }
1086       png_save_uint_16(buf, tran->gray);
1087       png_write_chunk(png_ptr, (png_bytep)png_tRNS, buf, (png_size_t)2);
1088    }
1089    else if (color_type == PNG_COLOR_TYPE_RGB)
1090    {
1091       /* three 16 bit values */
1092       png_save_uint_16(buf, tran->red);
1093       png_save_uint_16(buf + 2, tran->green);
1094       png_save_uint_16(buf + 4, tran->blue);
1095       if(png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))
1096          {
1097             png_warning(png_ptr,
1098               "Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8");
1099             return;
1100          }
1101       png_write_chunk(png_ptr, (png_bytep)png_tRNS, buf, (png_size_t)6);
1102    }
1103    else
1104    {
1105       png_warning(png_ptr, "Can't write tRNS with an alpha channel");
1106    }
1107 }
1108 #endif
1109
1110 #if defined(PNG_WRITE_bKGD_SUPPORTED)
1111 /* write the background chunk */
1112 void /* PRIVATE */
1113 png_write_bKGD(png_structp png_ptr, png_color_16p back, int color_type)
1114 {
1115 #ifdef PNG_USE_LOCAL_ARRAYS
1116    PNG_bKGD;
1117 #endif
1118    png_byte buf[6];
1119
1120    png_debug(1, "in png_write_bKGD\n");
1121    if (color_type == PNG_COLOR_TYPE_PALETTE)
1122    {
1123       if (
1124 #if defined(PNG_MNG_FEATURES_SUPPORTED)
1125           (png_ptr->num_palette ||
1126           (!(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE))) &&
1127 #endif
1128          back->index > png_ptr->num_palette)
1129       {
1130          png_warning(png_ptr, "Invalid background palette index");
1131          return;
1132       }
1133       buf[0] = back->index;
1134       png_write_chunk(png_ptr, (png_bytep)png_bKGD, buf, (png_size_t)1);
1135    }
1136    else if (color_type & PNG_COLOR_MASK_COLOR)
1137    {
1138       png_save_uint_16(buf, back->red);
1139       png_save_uint_16(buf + 2, back->green);
1140       png_save_uint_16(buf + 4, back->blue);
1141       if(png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))
1142          {
1143             png_warning(png_ptr,
1144               "Ignoring attempt to write 16-bit bKGD chunk when bit_depth is 8");
1145             return;
1146          }
1147       png_write_chunk(png_ptr, (png_bytep)png_bKGD, buf, (png_size_t)6);
1148    }
1149    else
1150    {
1151       if(back->gray >= (1 << png_ptr->bit_depth))
1152       {
1153          png_warning(png_ptr,
1154            "Ignoring attempt to write bKGD chunk out-of-range for bit_depth");
1155          return;
1156       }
1157       png_save_uint_16(buf, back->gray);
1158       png_write_chunk(png_ptr, (png_bytep)png_bKGD, buf, (png_size_t)2);
1159    }
1160 }
1161 #endif
1162
1163 #if defined(PNG_WRITE_hIST_SUPPORTED)
1164 /* write the histogram */
1165 void /* PRIVATE */
1166 png_write_hIST(png_structp png_ptr, png_uint_16p hist, int num_hist)
1167 {
1168 #ifdef PNG_USE_LOCAL_ARRAYS
1169    PNG_hIST;
1170 #endif
1171    int i;
1172    png_byte buf[3];
1173
1174    png_debug(1, "in png_write_hIST\n");
1175    if (num_hist > (int)png_ptr->num_palette)
1176    {
1177       png_debug2(3, "num_hist = %d, num_palette = %d\n", num_hist,
1178          png_ptr->num_palette);
1179       png_warning(png_ptr, "Invalid number of histogram entries specified");
1180       return;
1181    }
1182
1183    png_write_chunk_start(png_ptr, (png_bytep)png_hIST, (png_uint_32)(num_hist * 2));
1184    for (i = 0; i < num_hist; i++)
1185    {
1186       png_save_uint_16(buf, hist[i]);
1187       png_write_chunk_data(png_ptr, buf, (png_size_t)2);
1188    }
1189    png_write_chunk_end(png_ptr);
1190 }
1191 #endif
1192
1193 #if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \
1194     defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
1195 /* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification,
1196  * and if invalid, correct the keyword rather than discarding the entire
1197  * chunk.  The PNG 1.0 specification requires keywords 1-79 characters in
1198  * length, forbids leading or trailing whitespace, multiple internal spaces,
1199  * and the non-break space (0x80) from ISO 8859-1.  Returns keyword length.
1200  *
1201  * The new_key is allocated to hold the corrected keyword and must be freed
1202  * by the calling routine.  This avoids problems with trying to write to
1203  * static keywords without having to have duplicate copies of the strings.
1204  */
1205 png_size_t /* PRIVATE */
1206 png_check_keyword(png_structp png_ptr, png_charp key, png_charpp new_key)
1207 {
1208    png_size_t key_len;
1209    png_charp kp, dp;
1210    int kflag;
1211    int kwarn=0;
1212
1213    png_debug(1, "in png_check_keyword\n");
1214    *new_key = NULL;
1215
1216    if (key == NULL || (key_len = png_strlen(key)) == 0)
1217    {
1218       png_warning(png_ptr, "zero length keyword");
1219       return ((png_size_t)0);
1220    }
1221
1222    png_debug1(2, "Keyword to be checked is '%s'\n", key);
1223
1224    *new_key = (png_charp)png_malloc_warn(png_ptr, (png_uint_32)(key_len + 2));
1225    if (*new_key == NULL)
1226    {
1227       png_warning(png_ptr, "Out of memory while procesing keyword");
1228       return ((png_size_t)0);
1229    }
1230
1231    /* Replace non-printing characters with a blank and print a warning */
1232    for (kp = key, dp = *new_key; *kp != '\0'; kp++, dp++)
1233    {
1234       if (*kp < 0x20 || (*kp > 0x7E && (png_byte)*kp < 0xA1))
1235       {
1236 #if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
1237          char msg[40];
1238
1239          sprintf(msg, "invalid keyword character 0x%02X", *kp);
1240          png_warning(png_ptr, msg);
1241 #else
1242          png_warning(png_ptr, "invalid character in keyword");
1243 #endif
1244          *dp = ' ';
1245       }
1246       else
1247       {
1248          *dp = *kp;
1249       }
1250    }
1251    *dp = '\0';
1252
1253    /* Remove any trailing white space. */
1254    kp = *new_key + key_len - 1;
1255    if (*kp == ' ')
1256    {
1257       png_warning(png_ptr, "trailing spaces removed from keyword");
1258
1259       while (*kp == ' ')
1260       {
1261         *(kp--) = '\0';
1262         key_len--;
1263       }
1264    }
1265
1266    /* Remove any leading white space. */
1267    kp = *new_key;
1268    if (*kp == ' ')
1269    {
1270       png_warning(png_ptr, "leading spaces removed from keyword");
1271
1272       while (*kp == ' ')
1273       {
1274         kp++;
1275         key_len--;
1276       }
1277    }
1278
1279    png_debug1(2, "Checking for multiple internal spaces in '%s'\n", kp);
1280
1281    /* Remove multiple internal spaces. */
1282    for (kflag = 0, dp = *new_key; *kp != '\0'; kp++)
1283    {
1284       if (*kp == ' ' && kflag == 0)
1285       {
1286          *(dp++) = *kp;
1287          kflag = 1;
1288       }
1289       else if (*kp == ' ')
1290       {
1291          key_len--;
1292          kwarn=1;
1293       }
1294       else
1295       {
1296          *(dp++) = *kp;
1297          kflag = 0;
1298       }
1299    }
1300    *dp = '\0';
1301    if(kwarn)
1302       png_warning(png_ptr, "extra interior spaces removed from keyword");
1303
1304    if (key_len == 0)
1305    {
1306       png_free(png_ptr, *new_key);
1307       *new_key=NULL;
1308       png_warning(png_ptr, "Zero length keyword");
1309    }
1310
1311    if (key_len > 79)
1312    {
1313       png_warning(png_ptr, "keyword length must be 1 - 79 characters");
1314       new_key[79] = '\0';
1315       key_len = 79;
1316    }
1317
1318    return (key_len);
1319 }
1320 #endif
1321
1322 #if defined(PNG_WRITE_tEXt_SUPPORTED)
1323 /* write a tEXt chunk */
1324 void /* PRIVATE */
1325 png_write_tEXt(png_structp png_ptr, png_charp key, png_charp text,
1326    png_size_t text_len)
1327 {
1328 #ifdef PNG_USE_LOCAL_ARRAYS
1329    PNG_tEXt;
1330 #endif
1331    png_size_t key_len;
1332    png_charp new_key;
1333
1334    png_debug(1, "in png_write_tEXt\n");
1335    if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0)
1336    {
1337       png_warning(png_ptr, "Empty keyword in tEXt chunk");
1338       return;
1339    }
1340
1341    if (text == NULL || *text == '\0')
1342       text_len = 0;
1343    else
1344       text_len = png_strlen(text);
1345
1346    /* make sure we include the 0 after the key */
1347    png_write_chunk_start(png_ptr, (png_bytep)png_tEXt, (png_uint_32)key_len+text_len+1);
1348    /*
1349     * We leave it to the application to meet PNG-1.0 requirements on the
1350     * contents of the text.  PNG-1.0 through PNG-1.2 discourage the use of
1351     * any non-Latin-1 characters except for NEWLINE.  ISO PNG will forbid them.
1352     * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1353     */
1354    png_write_chunk_data(png_ptr, (png_bytep)new_key, key_len + 1);
1355    if (text_len)
1356       png_write_chunk_data(png_ptr, (png_bytep)text, text_len);
1357
1358    png_write_chunk_end(png_ptr);
1359    png_free(png_ptr, new_key);
1360 }
1361 #endif
1362
1363 #if defined(PNG_WRITE_zTXt_SUPPORTED)
1364 /* write a compressed text chunk */
1365 void /* PRIVATE */
1366 png_write_zTXt(png_structp png_ptr, png_charp key, png_charp text,
1367    png_size_t text_len, int compression)
1368 {
1369 #ifdef PNG_USE_LOCAL_ARRAYS
1370    PNG_zTXt;
1371 #endif
1372    png_size_t key_len;
1373    char buf[1];
1374    png_charp new_key;
1375    compression_state comp;
1376
1377    png_debug(1, "in png_write_zTXt\n");
1378
1379    comp.num_output_ptr = 0;
1380    comp.max_output_ptr = 0;
1381    comp.output_ptr = NULL;
1382    comp.input = NULL;
1383    comp.input_len = 0;
1384
1385    if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0)
1386    {
1387       png_warning(png_ptr, "Empty keyword in zTXt chunk");
1388       return;
1389    }
1390
1391    if (text == NULL || *text == '\0' || compression==PNG_TEXT_COMPRESSION_NONE)
1392    {
1393       png_write_tEXt(png_ptr, new_key, text, (png_size_t)0);
1394       png_free(png_ptr, new_key);
1395       return;
1396    }
1397
1398    text_len = png_strlen(text);
1399
1400    png_free(png_ptr, new_key);
1401
1402    /* compute the compressed data; do it now for the length */
1403    text_len = png_text_compress(png_ptr, text, text_len, compression,
1404        &comp);
1405
1406    /* write start of chunk */
1407    png_write_chunk_start(png_ptr, (png_bytep)png_zTXt, (png_uint_32)
1408       (key_len+text_len+2));
1409    /* write key */
1410    png_write_chunk_data(png_ptr, (png_bytep)key, key_len + 1);
1411    buf[0] = (png_byte)compression;
1412    /* write compression */
1413    png_write_chunk_data(png_ptr, (png_bytep)buf, (png_size_t)1);
1414    /* write the compressed data */
1415    png_write_compressed_data_out(png_ptr, &comp);
1416
1417    /* close the chunk */
1418    png_write_chunk_end(png_ptr);
1419 }
1420 #endif
1421
1422 #if defined(PNG_WRITE_iTXt_SUPPORTED)
1423 /* write an iTXt chunk */
1424 void /* PRIVATE */
1425 png_write_iTXt(png_structp png_ptr, int compression, png_charp key,
1426     png_charp lang, png_charp lang_key, png_charp text)
1427 {
1428 #ifdef PNG_USE_LOCAL_ARRAYS
1429    PNG_iTXt;
1430 #endif
1431    png_size_t lang_len, key_len, lang_key_len, text_len;
1432    png_charp new_lang, new_key;
1433    png_byte cbuf[2];
1434    compression_state comp;
1435
1436    png_debug(1, "in png_write_iTXt\n");
1437
1438    comp.num_output_ptr = 0;
1439    comp.max_output_ptr = 0;
1440    comp.output_ptr = NULL;
1441    comp.input = NULL;
1442
1443    if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0)
1444    {
1445       png_warning(png_ptr, "Empty keyword in iTXt chunk");
1446       return;
1447    }
1448    if (lang == NULL || (lang_len = png_check_keyword(png_ptr, lang, &new_lang))==0)
1449    {
1450       png_warning(png_ptr, "Empty language field in iTXt chunk");
1451       new_lang = NULL;
1452       lang_len = 0;
1453    }
1454
1455    if (lang_key == NULL)
1456      lang_key_len = 0;
1457    else
1458      lang_key_len = png_strlen(lang_key);
1459
1460    if (text == NULL)
1461       text_len = 0;
1462    else
1463      text_len = png_strlen(text);
1464
1465    /* compute the compressed data; do it now for the length */
1466    text_len = png_text_compress(png_ptr, text, text_len, compression-2,
1467       &comp);
1468
1469
1470    /* make sure we include the compression flag, the compression byte,
1471     * and the NULs after the key, lang, and lang_key parts */
1472
1473    png_write_chunk_start(png_ptr, (png_bytep)png_iTXt,
1474           (png_uint_32)(
1475         5 /* comp byte, comp flag, terminators for key, lang and lang_key */
1476         + key_len
1477         + lang_len
1478         + lang_key_len
1479         + text_len));
1480
1481    /*
1482     * We leave it to the application to meet PNG-1.0 requirements on the
1483     * contents of the text.  PNG-1.0 through PNG-1.2 discourage the use of
1484     * any non-Latin-1 characters except for NEWLINE.  ISO PNG will forbid them.
1485     * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1486     */
1487    png_write_chunk_data(png_ptr, (png_bytep)new_key, key_len + 1);
1488
1489    /* set the compression flag */
1490    if (compression == PNG_ITXT_COMPRESSION_NONE || \
1491        compression == PNG_TEXT_COMPRESSION_NONE)
1492        cbuf[0] = 0;
1493    else /* compression == PNG_ITXT_COMPRESSION_zTXt */
1494        cbuf[0] = 1;
1495    /* set the compression method */
1496    cbuf[1] = 0;
1497    png_write_chunk_data(png_ptr, cbuf, 2);
1498
1499    cbuf[0] = 0;
1500    png_write_chunk_data(png_ptr, (new_lang ? (png_bytep)new_lang : cbuf), lang_len + 1);
1501    png_write_chunk_data(png_ptr, (lang_key ? (png_bytep)lang_key : cbuf), lang_key_len + 1);
1502    png_write_compressed_data_out(png_ptr, &comp);
1503
1504    png_write_chunk_end(png_ptr);
1505    png_free(png_ptr, new_key);
1506    if (new_lang)
1507      png_free(png_ptr, new_lang);
1508 }
1509 #endif
1510
1511 #if defined(PNG_WRITE_oFFs_SUPPORTED)
1512 /* write the oFFs chunk */
1513 void /* PRIVATE */
1514 png_write_oFFs(png_structp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
1515    int unit_type)
1516 {
1517 #ifdef PNG_USE_LOCAL_ARRAYS
1518    PNG_oFFs;
1519 #endif
1520    png_byte buf[9];
1521
1522    png_debug(1, "in png_write_oFFs\n");
1523    if (unit_type >= PNG_OFFSET_LAST)
1524       png_warning(png_ptr, "Unrecognized unit type for oFFs chunk");
1525
1526    png_save_int_32(buf, x_offset);
1527    png_save_int_32(buf + 4, y_offset);
1528    buf[8] = (png_byte)unit_type;
1529
1530    png_write_chunk(png_ptr, (png_bytep)png_oFFs, buf, (png_size_t)9);
1531 }
1532 #endif
1533
1534 #if defined(PNG_WRITE_pCAL_SUPPORTED)
1535 /* write the pCAL chunk (described in the PNG extensions document) */
1536 void /* PRIVATE */
1537 png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
1538    png_int_32 X1, int type, int nparams, png_charp units, png_charpp params)
1539 {
1540 #ifdef PNG_USE_LOCAL_ARRAYS
1541    PNG_pCAL;
1542 #endif
1543    png_size_t purpose_len, units_len, total_len;
1544    png_uint_32p params_len;
1545    png_byte buf[10];
1546    png_charp new_purpose;
1547    int i;
1548
1549    png_debug1(1, "in png_write_pCAL (%d parameters)\n", nparams);
1550    if (type >= PNG_EQUATION_LAST)
1551       png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");
1552
1553    purpose_len = png_check_keyword(png_ptr, purpose, &new_purpose) + 1;
1554    png_debug1(3, "pCAL purpose length = %d\n", (int)purpose_len);
1555    units_len = png_strlen(units) + (nparams == 0 ? 0 : 1);
1556    png_debug1(3, "pCAL units length = %d\n", (int)units_len);
1557    total_len = purpose_len + units_len + 10;
1558
1559    params_len = (png_uint_32p)png_malloc(png_ptr, (png_uint_32)(nparams
1560       *png_sizeof(png_uint_32)));
1561
1562    /* Find the length of each parameter, making sure we don't count the
1563       null terminator for the last parameter. */
1564    for (i = 0; i < nparams; i++)
1565    {
1566       params_len[i] = png_strlen(params[i]) + (i == nparams - 1 ? 0 : 1);
1567       png_debug2(3, "pCAL parameter %d length = %lu\n", i, params_len[i]);
1568       total_len += (png_size_t)params_len[i];
1569    }
1570
1571    png_debug1(3, "pCAL total length = %d\n", (int)total_len);
1572    png_write_chunk_start(png_ptr, (png_bytep)png_pCAL, (png_uint_32)total_len);
1573    png_write_chunk_data(png_ptr, (png_bytep)new_purpose, purpose_len);
1574    png_save_int_32(buf, X0);
1575    png_save_int_32(buf + 4, X1);
1576    buf[8] = (png_byte)type;
1577    buf[9] = (png_byte)nparams;
1578    png_write_chunk_data(png_ptr, buf, (png_size_t)10);
1579    png_write_chunk_data(png_ptr, (png_bytep)units, (png_size_t)units_len);
1580
1581    png_free(png_ptr, new_purpose);
1582
1583    for (i = 0; i < nparams; i++)
1584    {
1585       png_write_chunk_data(png_ptr, (png_bytep)params[i],
1586          (png_size_t)params_len[i]);
1587    }
1588
1589    png_free(png_ptr, params_len);
1590    png_write_chunk_end(png_ptr);
1591 }
1592 #endif
1593
1594 #if defined(PNG_WRITE_sCAL_SUPPORTED)
1595 /* write the sCAL chunk */
1596 #if defined(PNG_FLOATING_POINT_SUPPORTED) && !defined(PNG_NO_STDIO)
1597 void /* PRIVATE */
1598 png_write_sCAL(png_structp png_ptr, int unit, double width, double height)
1599 {
1600 #ifdef PNG_USE_LOCAL_ARRAYS
1601    PNG_sCAL;
1602 #endif
1603    char buf[64];
1604    png_size_t total_len;
1605
1606    png_debug(1, "in png_write_sCAL\n");
1607
1608    buf[0] = (char)unit;
1609 #if defined(_WIN32_WCE)
1610 /* sprintf() function is not supported on WindowsCE */
1611    {
1612       wchar_t wc_buf[32];
1613       size_t wc_len;
1614       swprintf(wc_buf, TEXT("%12.12e"), width);
1615       wc_len = wcslen(wc_buf);
1616       WideCharToMultiByte(CP_ACP, 0, wc_buf, -1, buf + 1, wc_len, NULL, NULL);
1617       total_len = wc_len + 2;
1618       swprintf(wc_buf, TEXT("%12.12e"), height);
1619       wc_len = wcslen(wc_buf);
1620       WideCharToMultiByte(CP_ACP, 0, wc_buf, -1, buf + total_len, wc_len,
1621          NULL, NULL);
1622       total_len += wc_len;
1623    }
1624 #else
1625    sprintf(buf + 1, "%12.12e", width);
1626    total_len = 1 + png_strlen(buf + 1) + 1;
1627    sprintf(buf + total_len, "%12.12e", height);
1628    total_len += png_strlen(buf + total_len);
1629 #endif
1630
1631    png_debug1(3, "sCAL total length = %u\n", (unsigned int)total_len);
1632    png_write_chunk(png_ptr, (png_bytep)png_sCAL, (png_bytep)buf, total_len);
1633 }
1634 #else
1635 #ifdef PNG_FIXED_POINT_SUPPORTED
1636 void /* PRIVATE */
1637 png_write_sCAL_s(png_structp png_ptr, int unit, png_charp width,
1638    png_charp height)
1639 {
1640 #ifdef PNG_USE_LOCAL_ARRAYS
1641    PNG_sCAL;
1642 #endif
1643    png_byte buf[64];
1644    png_size_t wlen, hlen, total_len;
1645
1646    png_debug(1, "in png_write_sCAL_s\n");
1647
1648    wlen = png_strlen(width);
1649    hlen = png_strlen(height);
1650    total_len = wlen + hlen + 2;
1651    if (total_len > 64)
1652    {
1653       png_warning(png_ptr, "Can't write sCAL (buffer too small)");
1654       return;
1655    }
1656
1657    buf[0] = (png_byte)unit;
1658    png_memcpy(buf + 1, width, wlen + 1);      /* append the '\0' here */
1659    png_memcpy(buf + wlen + 2, height, hlen);  /* do NOT append the '\0' here */
1660
1661    png_debug1(3, "sCAL total length = %u\n", (unsigned int)total_len);
1662    png_write_chunk(png_ptr, (png_bytep)png_sCAL, buf, total_len);
1663 }
1664 #endif
1665 #endif
1666 #endif
1667
1668 #if defined(PNG_WRITE_pHYs_SUPPORTED)
1669 /* write the pHYs chunk */
1670 void /* PRIVATE */
1671 png_write_pHYs(png_structp png_ptr, png_uint_32 x_pixels_per_unit,
1672    png_uint_32 y_pixels_per_unit,
1673    int unit_type)
1674 {
1675 #ifdef PNG_USE_LOCAL_ARRAYS
1676    PNG_pHYs;
1677 #endif
1678    png_byte buf[9];
1679
1680    png_debug(1, "in png_write_pHYs\n");
1681    if (unit_type >= PNG_RESOLUTION_LAST)
1682       png_warning(png_ptr, "Unrecognized unit type for pHYs chunk");
1683
1684    png_save_uint_32(buf, x_pixels_per_unit);
1685    png_save_uint_32(buf + 4, y_pixels_per_unit);
1686    buf[8] = (png_byte)unit_type;
1687
1688    png_write_chunk(png_ptr, (png_bytep)png_pHYs, buf, (png_size_t)9);
1689 }
1690 #endif
1691
1692 #if defined(PNG_WRITE_tIME_SUPPORTED)
1693 /* Write the tIME chunk.  Use either png_convert_from_struct_tm()
1694  * or png_convert_from_time_t(), or fill in the structure yourself.
1695  */
1696 void /* PRIVATE */
1697 png_write_tIME(png_structp png_ptr, png_timep mod_time)
1698 {
1699 #ifdef PNG_USE_LOCAL_ARRAYS
1700    PNG_tIME;
1701 #endif
1702    png_byte buf[7];
1703
1704    png_debug(1, "in png_write_tIME\n");
1705    if (mod_time->month  > 12 || mod_time->month  < 1 ||
1706        mod_time->day    > 31 || mod_time->day    < 1 ||
1707        mod_time->hour   > 23 || mod_time->second > 60)
1708    {
1709       png_warning(png_ptr, "Invalid time specified for tIME chunk");
1710       return;
1711    }
1712
1713    png_save_uint_16(buf, mod_time->year);
1714    buf[2] = mod_time->month;
1715    buf[3] = mod_time->day;
1716    buf[4] = mod_time->hour;
1717    buf[5] = mod_time->minute;
1718    buf[6] = mod_time->second;
1719
1720    png_write_chunk(png_ptr, (png_bytep)png_tIME, buf, (png_size_t)7);
1721 }
1722 #endif
1723
1724 /* initializes the row writing capability of libpng */
1725 void /* PRIVATE */
1726 png_write_start_row(png_structp png_ptr)
1727 {
1728 #ifdef PNG_USE_LOCAL_ARRAYS
1729    /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1730
1731    /* start of interlace block */
1732    int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
1733
1734    /* offset to next interlace block */
1735    int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
1736
1737    /* start of interlace block in the y direction */
1738    int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
1739
1740    /* offset to next interlace block in the y direction */
1741    int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
1742 #endif
1743
1744    png_size_t buf_size;
1745
1746    png_debug(1, "in png_write_start_row\n");
1747    buf_size = (png_size_t)(PNG_ROWBYTES(
1748       png_ptr->usr_channels*png_ptr->usr_bit_depth,png_ptr->width)+1);
1749
1750    /* set up row buffer */
1751    png_ptr->row_buf = (png_bytep)png_malloc(png_ptr, (png_uint_32)buf_size);
1752    png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE;
1753
1754    /* set up filtering buffer, if using this filter */
1755    if (png_ptr->do_filter & PNG_FILTER_SUB)
1756    {
1757       png_ptr->sub_row = (png_bytep)png_malloc(png_ptr,
1758          (png_ptr->rowbytes + 1));
1759       png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
1760    }
1761
1762    /* We only need to keep the previous row if we are using one of these. */
1763    if (png_ptr->do_filter & (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH))
1764    {
1765      /* set up previous row buffer */
1766       png_ptr->prev_row = (png_bytep)png_malloc(png_ptr, (png_uint_32)buf_size);
1767       png_memset(png_ptr->prev_row, 0, buf_size);
1768
1769       if (png_ptr->do_filter & PNG_FILTER_UP)
1770       {
1771          png_ptr->up_row = (png_bytep )png_malloc(png_ptr,
1772             (png_ptr->rowbytes + 1));
1773          png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;
1774       }
1775
1776       if (png_ptr->do_filter & PNG_FILTER_AVG)
1777       {
1778          png_ptr->avg_row = (png_bytep)png_malloc(png_ptr,
1779             (png_ptr->rowbytes + 1));
1780          png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;
1781       }
1782
1783       if (png_ptr->do_filter & PNG_FILTER_PAETH)
1784       {
1785          png_ptr->paeth_row = (png_bytep )png_malloc(png_ptr,
1786             (png_ptr->rowbytes + 1));
1787          png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
1788       }
1789    }
1790
1791 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
1792    /* if interlaced, we need to set up width and height of pass */
1793    if (png_ptr->interlaced)
1794    {
1795       if (!(png_ptr->transformations & PNG_INTERLACE))
1796       {
1797          png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
1798             png_pass_ystart[0]) / png_pass_yinc[0];
1799          png_ptr->usr_width = (png_ptr->width + png_pass_inc[0] - 1 -
1800             png_pass_start[0]) / png_pass_inc[0];
1801       }
1802       else
1803       {
1804          png_ptr->num_rows = png_ptr->height;
1805          png_ptr->usr_width = png_ptr->width;
1806       }
1807    }
1808    else
1809 #endif
1810    {
1811       png_ptr->num_rows = png_ptr->height;
1812       png_ptr->usr_width = png_ptr->width;
1813    }
1814    png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1815    png_ptr->zstream.next_out = png_ptr->zbuf;
1816 }
1817
1818 /* Internal use only.  Called when finished processing a row of data. */
1819 void /* PRIVATE */
1820 png_write_finish_row(png_structp png_ptr)
1821 {
1822 #ifdef PNG_USE_LOCAL_ARRAYS
1823    /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1824
1825    /* start of interlace block */
1826    int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
1827
1828    /* offset to next interlace block */
1829    int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
1830
1831    /* start of interlace block in the y direction */
1832    int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
1833
1834    /* offset to next interlace block in the y direction */
1835    int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
1836 #endif
1837
1838    int ret;
1839
1840    png_debug(1, "in png_write_finish_row\n");
1841    /* next row */
1842    png_ptr->row_number++;
1843
1844    /* see if we are done */
1845    if (png_ptr->row_number < png_ptr->num_rows)
1846       return;
1847
1848 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
1849    /* if interlaced, go to next pass */
1850    if (png_ptr->interlaced)
1851    {
1852       png_ptr->row_number = 0;
1853       if (png_ptr->transformations & PNG_INTERLACE)
1854       {
1855          png_ptr->pass++;
1856       }
1857       else
1858       {
1859          /* loop until we find a non-zero width or height pass */
1860          do
1861          {
1862             png_ptr->pass++;
1863             if (png_ptr->pass >= 7)
1864                break;
1865             png_ptr->usr_width = (png_ptr->width +
1866                png_pass_inc[png_ptr->pass] - 1 -
1867                png_pass_start[png_ptr->pass]) /
1868                png_pass_inc[png_ptr->pass];
1869             png_ptr->num_rows = (png_ptr->height +
1870                png_pass_yinc[png_ptr->pass] - 1 -
1871                png_pass_ystart[png_ptr->pass]) /
1872                png_pass_yinc[png_ptr->pass];
1873             if (png_ptr->transformations & PNG_INTERLACE)
1874                break;
1875          } while (png_ptr->usr_width == 0 || png_ptr->num_rows == 0);
1876
1877       }
1878
1879       /* reset the row above the image for the next pass */
1880       if (png_ptr->pass < 7)
1881       {
1882          if (png_ptr->prev_row != NULL)
1883             png_memset(png_ptr->prev_row, 0,
1884                (png_size_t)(PNG_ROWBYTES(png_ptr->usr_channels*
1885                png_ptr->usr_bit_depth,png_ptr->width))+1);
1886          return;
1887       }
1888    }
1889 #endif
1890
1891    /* if we get here, we've just written the last row, so we need
1892       to flush the compressor */
1893    do
1894    {
1895       /* tell the compressor we are done */
1896       ret = deflate(&png_ptr->zstream, Z_FINISH);
1897       /* check for an error */
1898       if (ret == Z_OK)
1899       {
1900          /* check to see if we need more room */
1901          if (!(png_ptr->zstream.avail_out))
1902          {
1903             png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
1904             png_ptr->zstream.next_out = png_ptr->zbuf;
1905             png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1906          }
1907       }
1908       else if (ret != Z_STREAM_END)
1909       {
1910          if (png_ptr->zstream.msg != NULL)
1911             png_error(png_ptr, png_ptr->zstream.msg);
1912          else
1913             png_error(png_ptr, "zlib error");
1914       }
1915    } while (ret != Z_STREAM_END);
1916
1917    /* write any extra space */
1918    if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
1919    {
1920       png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size -
1921          png_ptr->zstream.avail_out);
1922    }
1923
1924    deflateReset(&png_ptr->zstream);
1925    png_ptr->zstream.data_type = Z_BINARY;
1926 }
1927
1928 #if defined(PNG_WRITE_INTERLACING_SUPPORTED)
1929 /* Pick out the correct pixels for the interlace pass.
1930  * The basic idea here is to go through the row with a source
1931  * pointer and a destination pointer (sp and dp), and copy the
1932  * correct pixels for the pass.  As the row gets compacted,
1933  * sp will always be >= dp, so we should never overwrite anything.
1934  * See the default: case for the easiest code to understand.
1935  */
1936 void /* PRIVATE */
1937 png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
1938 {
1939 #ifdef PNG_USE_LOCAL_ARRAYS
1940    /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1941
1942    /* start of interlace block */
1943    int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
1944
1945    /* offset to next interlace block */
1946    int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
1947 #endif
1948
1949    png_debug(1, "in png_do_write_interlace\n");
1950    /* we don't have to do anything on the last pass (6) */
1951 #if defined(PNG_USELESS_TESTS_SUPPORTED)
1952    if (row != NULL && row_info != NULL && pass < 6)
1953 #else
1954    if (pass < 6)
1955 #endif
1956    {
1957       /* each pixel depth is handled separately */
1958       switch (row_info->pixel_depth)
1959       {
1960          case 1:
1961          {
1962             png_bytep sp;
1963             png_bytep dp;
1964             int shift;
1965             int d;
1966             int value;
1967             png_uint_32 i;
1968             png_uint_32 row_width = row_info->width;
1969
1970             dp = row;
1971             d = 0;
1972             shift = 7;
1973             for (i = png_pass_start[pass]; i < row_width;
1974                i += png_pass_inc[pass])
1975             {
1976                sp = row + (png_size_t)(i >> 3);
1977                value = (int)(*sp >> (7 - (int)(i & 0x07))) & 0x01;
1978                d |= (value << shift);
1979
1980                if (shift == 0)
1981                {
1982                   shift = 7;
1983                   *dp++ = (png_byte)d;
1984                   d = 0;
1985                }
1986                else
1987                   shift--;
1988
1989             }
1990             if (shift != 7)
1991                *dp = (png_byte)d;
1992             break;
1993          }
1994          case 2:
1995          {
1996             png_bytep sp;
1997             png_bytep dp;
1998             int shift;
1999             int d;
2000             int value;
2001             png_uint_32 i;
2002             png_uint_32 row_width = row_info->width;
2003
2004             dp = row;
2005             shift = 6;
2006             d = 0;
2007             for (i = png_pass_start[pass]; i < row_width;
2008                i += png_pass_inc[pass])
2009             {
2010                sp = row + (png_size_t)(i >> 2);
2011                value = (*sp >> ((3 - (int)(i & 0x03)) << 1)) & 0x03;
2012                d |= (value << shift);
2013
2014                if (shift == 0)
2015                {
2016                   shift = 6;
2017                   *dp++ = (png_byte)d;
2018                   d = 0;
2019                }
2020                else
2021                   shift -= 2;
2022             }
2023             if (shift != 6)
2024                    *dp = (png_byte)d;
2025             break;
2026          }
2027          case 4:
2028          {
2029             png_bytep sp;
2030             png_bytep dp;
2031             int shift;
2032             int d;
2033             int value;
2034             png_uint_32 i;
2035             png_uint_32 row_width = row_info->width;
2036
2037             dp = row;
2038             shift = 4;
2039             d = 0;
2040             for (i = png_pass_start[pass]; i < row_width;
2041                i += png_pass_inc[pass])
2042             {
2043                sp = row + (png_size_t)(i >> 1);
2044                value = (*sp >> ((1 - (int)(i & 0x01)) << 2)) & 0x0f;
2045                d |= (value << shift);
2046
2047                if (shift == 0)
2048                {
2049                   shift = 4;
2050                   *dp++ = (png_byte)d;
2051                   d = 0;
2052                }
2053                else
2054                   shift -= 4;
2055             }
2056             if (shift != 4)
2057                *dp = (png_byte)d;
2058             break;
2059          }
2060          default:
2061          {
2062             png_bytep sp;
2063             png_bytep dp;
2064             png_uint_32 i;
2065             png_uint_32 row_width = row_info->width;
2066             png_size_t pixel_bytes;
2067
2068             /* start at the beginning */
2069             dp = row;
2070             /* find out how many bytes each pixel takes up */
2071             pixel_bytes = (row_info->pixel_depth >> 3);
2072             /* loop through the row, only looking at the pixels that
2073                matter */
2074             for (i = png_pass_start[pass]; i < row_width;
2075                i += png_pass_inc[pass])
2076             {
2077                /* find out where the original pixel is */
2078                sp = row + (png_size_t)i * pixel_bytes;
2079                /* move the pixel */
2080                if (dp != sp)
2081                   png_memcpy(dp, sp, pixel_bytes);
2082                /* next pixel */
2083                dp += pixel_bytes;
2084             }
2085             break;
2086          }
2087       }
2088       /* set new row width */
2089       row_info->width = (row_info->width +
2090          png_pass_inc[pass] - 1 -
2091          png_pass_start[pass]) /
2092          png_pass_inc[pass];
2093          row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
2094             row_info->width);
2095    }
2096 }
2097 #endif
2098
2099 /* This filters the row, chooses which filter to use, if it has not already
2100  * been specified by the application, and then writes the row out with the
2101  * chosen filter.
2102  */
2103 #define PNG_MAXSUM (((png_uint_32)(-1)) >> 1)
2104 #define PNG_HISHIFT 10
2105 #define PNG_LOMASK ((png_uint_32)0xffffL)
2106 #define PNG_HIMASK ((png_uint_32)(~PNG_LOMASK >> PNG_HISHIFT))
2107 void /* PRIVATE */
2108 png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
2109 {
2110    png_bytep prev_row, best_row, row_buf;
2111    png_uint_32 mins, bpp;
2112    png_byte filter_to_do = png_ptr->do_filter;
2113    png_uint_32 row_bytes = row_info->rowbytes;
2114 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2115    int num_p_filters = (int)png_ptr->num_prev_filters;
2116 #endif
2117
2118    png_debug(1, "in png_write_find_filter\n");
2119    /* find out how many bytes offset each pixel is */
2120    bpp = (row_info->pixel_depth + 7) >> 3;
2121
2122    prev_row = png_ptr->prev_row;
2123    best_row = row_buf = png_ptr->row_buf;
2124    mins = PNG_MAXSUM;
2125
2126    /* The prediction method we use is to find which method provides the
2127     * smallest value when summing the absolute values of the distances
2128     * from zero, using anything >= 128 as negative numbers.  This is known
2129     * as the "minimum sum of absolute differences" heuristic.  Other
2130     * heuristics are the "weighted minimum sum of absolute differences"
2131     * (experimental and can in theory improve compression), and the "zlib
2132     * predictive" method (not implemented yet), which does test compressions
2133     * of lines using different filter methods, and then chooses the
2134     * (series of) filter(s) that give minimum compressed data size (VERY
2135     * computationally expensive).
2136     *
2137     * GRR 980525:  consider also
2138     *   (1) minimum sum of absolute differences from running average (i.e.,
2139     *       keep running sum of non-absolute differences & count of bytes)
2140     *       [track dispersion, too?  restart average if dispersion too large?]
2141     *  (1b) minimum sum of absolute differences from sliding average, probably
2142     *       with window size <= deflate window (usually 32K)
2143     *   (2) minimum sum of squared differences from zero or running average
2144     *       (i.e., ~ root-mean-square approach)
2145     */
2146
2147
2148    /* We don't need to test the 'no filter' case if this is the only filter
2149     * that has been chosen, as it doesn't actually do anything to the data.
2150     */
2151    if ((filter_to_do & PNG_FILTER_NONE) &&
2152        filter_to_do != PNG_FILTER_NONE)
2153    {
2154       png_bytep rp;
2155       png_uint_32 sum = 0;
2156       png_uint_32 i;
2157       int v;
2158
2159       for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
2160       {
2161          v = *rp;
2162          sum += (v < 128) ? v : 256 - v;
2163       }
2164
2165 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2166       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2167       {
2168          png_uint_32 sumhi, sumlo;
2169          int j;
2170          sumlo = sum & PNG_LOMASK;
2171          sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; /* Gives us some footroom */
2172
2173          /* Reduce the sum if we match any of the previous rows */
2174          for (j = 0; j < num_p_filters; j++)
2175          {
2176             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
2177             {
2178                sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2179                   PNG_WEIGHT_SHIFT;
2180                sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2181                   PNG_WEIGHT_SHIFT;
2182             }
2183          }
2184
2185          /* Factor in the cost of this filter (this is here for completeness,
2186           * but it makes no sense to have a "cost" for the NONE filter, as
2187           * it has the minimum possible computational cost - none).
2188           */
2189          sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
2190             PNG_COST_SHIFT;
2191          sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
2192             PNG_COST_SHIFT;
2193
2194          if (sumhi > PNG_HIMASK)
2195             sum = PNG_MAXSUM;
2196          else
2197             sum = (sumhi << PNG_HISHIFT) + sumlo;
2198       }
2199 #endif
2200       mins = sum;
2201    }
2202
2203    /* sub filter */
2204    if (filter_to_do == PNG_FILTER_SUB)
2205    /* it's the only filter so no testing is needed */
2206    {
2207       png_bytep rp, lp, dp;
2208       png_uint_32 i;
2209       for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
2210            i++, rp++, dp++)
2211       {
2212          *dp = *rp;
2213       }
2214       for (lp = row_buf + 1; i < row_bytes;
2215          i++, rp++, lp++, dp++)
2216       {
2217          *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
2218       }
2219       best_row = png_ptr->sub_row;
2220    }
2221
2222    else if (filter_to_do & PNG_FILTER_SUB)
2223    {
2224       png_bytep rp, dp, lp;
2225       png_uint_32 sum = 0, lmins = mins;
2226       png_uint_32 i;
2227       int v;
2228
2229 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2230       /* We temporarily increase the "minimum sum" by the factor we
2231        * would reduce the sum of this filter, so that we can do the
2232        * early exit comparison without scaling the sum each time.
2233        */
2234       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2235       {
2236          int j;
2237          png_uint_32 lmhi, lmlo;
2238          lmlo = lmins & PNG_LOMASK;
2239          lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2240
2241          for (j = 0; j < num_p_filters; j++)
2242          {
2243             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
2244             {
2245                lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2246                   PNG_WEIGHT_SHIFT;
2247                lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2248                   PNG_WEIGHT_SHIFT;
2249             }
2250          }
2251
2252          lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2253             PNG_COST_SHIFT;
2254          lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2255             PNG_COST_SHIFT;
2256
2257          if (lmhi > PNG_HIMASK)
2258             lmins = PNG_MAXSUM;
2259          else
2260             lmins = (lmhi << PNG_HISHIFT) + lmlo;
2261       }
2262 #endif
2263
2264       for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
2265            i++, rp++, dp++)
2266       {
2267          v = *dp = *rp;
2268
2269          sum += (v < 128) ? v : 256 - v;
2270       }
2271       for (lp = row_buf + 1; i < row_bytes;
2272          i++, rp++, lp++, dp++)
2273       {
2274          v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
2275
2276          sum += (v < 128) ? v : 256 - v;
2277
2278          if (sum > lmins)  /* We are already worse, don't continue. */
2279             break;
2280       }
2281
2282 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2283       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2284       {
2285          int j;
2286          png_uint_32 sumhi, sumlo;
2287          sumlo = sum & PNG_LOMASK;
2288          sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2289
2290          for (j = 0; j < num_p_filters; j++)
2291          {
2292             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
2293             {
2294                sumlo = (sumlo * png_ptr->inv_filter_weights[j]) >>
2295                   PNG_WEIGHT_SHIFT;
2296                sumhi = (sumhi * png_ptr->inv_filter_weights[j]) >>
2297                   PNG_WEIGHT_SHIFT;
2298             }
2299          }
2300
2301          sumlo = (sumlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2302             PNG_COST_SHIFT;
2303          sumhi = (sumhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2304             PNG_COST_SHIFT;
2305
2306          if (sumhi > PNG_HIMASK)
2307             sum = PNG_MAXSUM;
2308          else
2309             sum = (sumhi << PNG_HISHIFT) + sumlo;
2310       }
2311 #endif
2312
2313       if (sum < mins)
2314       {
2315          mins = sum;
2316          best_row = png_ptr->sub_row;
2317       }
2318    }
2319
2320    /* up filter */
2321    if (filter_to_do == PNG_FILTER_UP)
2322    {
2323       png_bytep rp, dp, pp;
2324       png_uint_32 i;
2325
2326       for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
2327            pp = prev_row + 1; i < row_bytes;
2328            i++, rp++, pp++, dp++)
2329       {
2330          *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
2331       }
2332       best_row = png_ptr->up_row;
2333    }
2334
2335    else if (filter_to_do & PNG_FILTER_UP)
2336    {
2337       png_bytep rp, dp, pp;
2338       png_uint_32 sum = 0, lmins = mins;
2339       png_uint_32 i;
2340       int v;
2341
2342
2343 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2344       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2345       {
2346          int j;
2347          png_uint_32 lmhi, lmlo;
2348          lmlo = lmins & PNG_LOMASK;
2349          lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2350
2351          for (j = 0; j < num_p_filters; j++)
2352          {
2353             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
2354             {
2355                lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2356                   PNG_WEIGHT_SHIFT;
2357                lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2358                   PNG_WEIGHT_SHIFT;
2359             }
2360          }
2361
2362          lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
2363             PNG_COST_SHIFT;
2364          lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
2365             PNG_COST_SHIFT;
2366
2367          if (lmhi > PNG_HIMASK)
2368             lmins = PNG_MAXSUM;
2369          else
2370             lmins = (lmhi << PNG_HISHIFT) + lmlo;
2371       }
2372 #endif
2373
2374       for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
2375            pp = prev_row + 1; i < row_bytes; i++)
2376       {
2377          v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2378
2379          sum += (v < 128) ? v : 256 - v;
2380
2381          if (sum > lmins)  /* We are already worse, don't continue. */
2382             break;
2383       }
2384
2385 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2386       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2387       {
2388          int j;
2389          png_uint_32 sumhi, sumlo;
2390          sumlo = sum & PNG_LOMASK;
2391          sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2392
2393          for (j = 0; j < num_p_filters; j++)
2394          {
2395             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
2396             {
2397                sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2398                   PNG_WEIGHT_SHIFT;
2399                sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2400                   PNG_WEIGHT_SHIFT;
2401             }
2402          }
2403
2404          sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
2405             PNG_COST_SHIFT;
2406          sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
2407             PNG_COST_SHIFT;
2408
2409          if (sumhi > PNG_HIMASK)
2410             sum = PNG_MAXSUM;
2411          else
2412             sum = (sumhi << PNG_HISHIFT) + sumlo;
2413       }
2414 #endif
2415
2416       if (sum < mins)
2417       {
2418          mins = sum;
2419          best_row = png_ptr->up_row;
2420       }
2421    }
2422
2423    /* avg filter */
2424    if (filter_to_do == PNG_FILTER_AVG)
2425    {
2426       png_bytep rp, dp, pp, lp;
2427       png_uint_32 i;
2428       for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
2429            pp = prev_row + 1; i < bpp; i++)
2430       {
2431          *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
2432       }
2433       for (lp = row_buf + 1; i < row_bytes; i++)
2434       {
2435          *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
2436                  & 0xff);
2437       }
2438       best_row = png_ptr->avg_row;
2439    }
2440
2441    else if (filter_to_do & PNG_FILTER_AVG)
2442    {
2443       png_bytep rp, dp, pp, lp;
2444       png_uint_32 sum = 0, lmins = mins;
2445       png_uint_32 i;
2446       int v;
2447
2448 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2449       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2450       {
2451          int j;
2452          png_uint_32 lmhi, lmlo;
2453          lmlo = lmins & PNG_LOMASK;
2454          lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2455
2456          for (j = 0; j < num_p_filters; j++)
2457          {
2458             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_AVG)
2459             {
2460                lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2461                   PNG_WEIGHT_SHIFT;
2462                lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2463                   PNG_WEIGHT_SHIFT;
2464             }
2465          }
2466
2467          lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
2468             PNG_COST_SHIFT;
2469          lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
2470             PNG_COST_SHIFT;
2471
2472          if (lmhi > PNG_HIMASK)
2473             lmins = PNG_MAXSUM;
2474          else
2475             lmins = (lmhi << PNG_HISHIFT) + lmlo;
2476       }
2477 #endif
2478
2479       for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
2480            pp = prev_row + 1; i < bpp; i++)
2481       {
2482          v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
2483
2484          sum += (v < 128) ? v : 256 - v;
2485       }
2486       for (lp = row_buf + 1; i < row_bytes; i++)
2487       {
2488          v = *dp++ =
2489           (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) & 0xff);
2490
2491          sum += (v < 128) ? v : 256 - v;
2492
2493          if (sum > lmins)  /* We are already worse, don't continue. */
2494             break;
2495       }
2496
2497 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2498       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2499       {
2500          int j;
2501          png_uint_32 sumhi, sumlo;
2502          sumlo = sum & PNG_LOMASK;
2503          sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2504
2505          for (j = 0; j < num_p_filters; j++)
2506          {
2507             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
2508             {
2509                sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2510                   PNG_WEIGHT_SHIFT;
2511                sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2512                   PNG_WEIGHT_SHIFT;
2513             }
2514          }
2515
2516          sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
2517             PNG_COST_SHIFT;
2518          sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
2519             PNG_COST_SHIFT;
2520
2521          if (sumhi > PNG_HIMASK)
2522             sum = PNG_MAXSUM;
2523          else
2524             sum = (sumhi << PNG_HISHIFT) + sumlo;
2525       }
2526 #endif
2527
2528       if (sum < mins)
2529       {
2530          mins = sum;
2531          best_row = png_ptr->avg_row;
2532       }
2533    }
2534
2535    /* Paeth filter */
2536    if (filter_to_do == PNG_FILTER_PAETH)
2537    {
2538       png_bytep rp, dp, pp, cp, lp;
2539       png_uint_32 i;
2540       for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
2541            pp = prev_row + 1; i < bpp; i++)
2542       {
2543          *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2544       }
2545
2546       for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
2547       {
2548          int a, b, c, pa, pb, pc, p;
2549
2550          b = *pp++;
2551          c = *cp++;
2552          a = *lp++;
2553
2554          p = b - c;
2555          pc = a - c;
2556
2557 #ifdef PNG_USE_ABS
2558          pa = abs(p);
2559          pb = abs(pc);
2560          pc = abs(p + pc);
2561 #else
2562          pa = p < 0 ? -p : p;
2563          pb = pc < 0 ? -pc : pc;
2564          pc = (p + pc) < 0 ? -(p + pc) : p + pc;
2565 #endif
2566
2567          p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
2568
2569          *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
2570       }
2571       best_row = png_ptr->paeth_row;
2572    }
2573
2574    else if (filter_to_do & PNG_FILTER_PAETH)
2575    {
2576       png_bytep rp, dp, pp, cp, lp;
2577       png_uint_32 sum = 0, lmins = mins;
2578       png_uint_32 i;
2579       int v;
2580
2581 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2582       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2583       {
2584          int j;
2585          png_uint_32 lmhi, lmlo;
2586          lmlo = lmins & PNG_LOMASK;
2587          lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2588
2589          for (j = 0; j < num_p_filters; j++)
2590          {
2591             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
2592             {
2593                lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2594                   PNG_WEIGHT_SHIFT;
2595                lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2596                   PNG_WEIGHT_SHIFT;
2597             }
2598          }
2599
2600          lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2601             PNG_COST_SHIFT;
2602          lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2603             PNG_COST_SHIFT;
2604
2605          if (lmhi > PNG_HIMASK)
2606             lmins = PNG_MAXSUM;
2607          else
2608             lmins = (lmhi << PNG_HISHIFT) + lmlo;
2609       }
2610 #endif
2611
2612       for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
2613            pp = prev_row + 1; i < bpp; i++)
2614       {
2615          v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2616
2617          sum += (v < 128) ? v : 256 - v;
2618       }
2619
2620       for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
2621       {
2622          int a, b, c, pa, pb, pc, p;
2623
2624          b = *pp++;
2625          c = *cp++;
2626          a = *lp++;
2627
2628 #ifndef PNG_SLOW_PAETH
2629          p = b - c;
2630          pc = a - c;
2631 #ifdef PNG_USE_ABS
2632          pa = abs(p);
2633          pb = abs(pc);
2634          pc = abs(p + pc);
2635 #else
2636          pa = p < 0 ? -p : p;
2637          pb = pc < 0 ? -pc : pc;
2638          pc = (p + pc) < 0 ? -(p + pc) : p + pc;
2639 #endif
2640          p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
2641 #else /* PNG_SLOW_PAETH */
2642          p = a + b - c;
2643          pa = abs(p - a);
2644          pb = abs(p - b);
2645          pc = abs(p - c);
2646          if (pa <= pb && pa <= pc)
2647             p = a;
2648          else if (pb <= pc)
2649             p = b;
2650          else
2651             p = c;
2652 #endif /* PNG_SLOW_PAETH */
2653
2654          v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
2655
2656          sum += (v < 128) ? v : 256 - v;
2657
2658          if (sum > lmins)  /* We are already worse, don't continue. */
2659             break;
2660       }
2661
2662 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2663       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2664       {
2665          int j;
2666          png_uint_32 sumhi, sumlo;
2667          sumlo = sum & PNG_LOMASK;
2668          sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2669
2670          for (j = 0; j < num_p_filters; j++)
2671          {
2672             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
2673             {
2674                sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2675                   PNG_WEIGHT_SHIFT;
2676                sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2677                   PNG_WEIGHT_SHIFT;
2678             }
2679          }
2680
2681          sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2682             PNG_COST_SHIFT;
2683          sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2684             PNG_COST_SHIFT;
2685
2686          if (sumhi > PNG_HIMASK)
2687             sum = PNG_MAXSUM;
2688          else
2689             sum = (sumhi << PNG_HISHIFT) + sumlo;
2690       }
2691 #endif
2692
2693       if (sum < mins)
2694       {
2695          best_row = png_ptr->paeth_row;
2696       }
2697    }
2698
2699    /* Do the actual writing of the filtered row data from the chosen filter. */
2700
2701    png_write_filtered_row(png_ptr, best_row);
2702
2703 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2704    /* Save the type of filter we picked this time for future calculations */
2705    if (png_ptr->num_prev_filters > 0)
2706    {
2707       int j;
2708       for (j = 1; j < num_p_filters; j++)
2709       {
2710          png_ptr->prev_filters[j] = png_ptr->prev_filters[j - 1];
2711       }
2712       png_ptr->prev_filters[j] = best_row[0];
2713    }
2714 #endif
2715 }
2716
2717
2718 /* Do the actual writing of a previously filtered row. */
2719 void /* PRIVATE */
2720 png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row)
2721 {
2722    png_debug(1, "in png_write_filtered_row\n");
2723    png_debug1(2, "filter = %d\n", filtered_row[0]);
2724    /* set up the zlib input buffer */
2725
2726    png_ptr->zstream.next_in = filtered_row;
2727    png_ptr->zstream.avail_in = (uInt)png_ptr->row_info.rowbytes + 1;
2728    /* repeat until we have compressed all the data */
2729    do
2730    {
2731       int ret; /* return of zlib */
2732
2733       /* compress the data */
2734       ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
2735       /* check for compression errors */
2736       if (ret != Z_OK)
2737       {
2738          if (png_ptr->zstream.msg != NULL)
2739             png_error(png_ptr, png_ptr->zstream.msg);
2740          else
2741             png_error(png_ptr, "zlib error");
2742       }
2743
2744       /* see if it is time to write another IDAT */
2745       if (!(png_ptr->zstream.avail_out))
2746       {
2747          /* write the IDAT and reset the zlib output buffer */
2748          png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
2749          png_ptr->zstream.next_out = png_ptr->zbuf;
2750          png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
2751       }
2752    /* repeat until all data has been compressed */
2753    } while (png_ptr->zstream.avail_in);
2754
2755    /* swap the current and previous rows */
2756    if (png_ptr->prev_row != NULL)
2757    {
2758       png_bytep tptr;
2759
2760       tptr = png_ptr->prev_row;
2761       png_ptr->prev_row = png_ptr->row_buf;
2762       png_ptr->row_buf = tptr;
2763    }
2764
2765    /* finish row - updates counters and flushes zlib if last row */
2766    png_write_finish_row(png_ptr);
2767
2768 #if defined(PNG_WRITE_FLUSH_SUPPORTED)
2769    png_ptr->flush_rows++;
2770
2771    if (png_ptr->flush_dist > 0 &&
2772        png_ptr->flush_rows >= png_ptr->flush_dist)
2773    {
2774       png_write_flush(png_ptr);
2775    }
2776 #endif
2777 }
2778 #endif /* PNG_WRITE_SUPPORTED */