rosapps/lib/libpng/pngwutil.c

   1
   2 /* pngwutil.c - utilities to write a PNG file
   3  *
   4  * Last changed in libpng 1.2.20 Septhember 3, 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       png_snprintf(msg, 50, "Unknown compression type %d", compression);
 186       png_warning(png_ptr, msg);
 187 #else
 188       png_warning(png_ptr, "Unknown compression type");
 189 #endif
 190    }
 191
 192    /* We can't write the chunk until we find out how much data we have,
 193     * which means we need to run the compressor first and save the
 194     * output.  This shouldn't be a problem, as the vast majority of
 195     * comments should be reasonable, but we will set up an array of
 196     * malloc'd pointers to be sure.
 197     *
 198     * If we knew the application was well behaved, we could simplify this
 199     * greatly by assuming we can always malloc an output buffer large
 200     * enough to hold the compressed text ((1001 * text_len / 1000) + 12)
 201     * and malloc this directly.  The only time this would be a bad idea is
 202     * if we can't malloc more than 64K and we have 64K of random input
 203     * data, or if the input string is incredibly large (although this
 204     * wouldn't cause a failure, just a slowdown due to swapping).
 205     */
 206
 207    /* set up the compression buffers */
 208    png_ptr->zstream.avail_in = (uInt)text_len;
 209    png_ptr->zstream.next_in = (Bytef *)text;
 210    png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
 211    png_ptr->zstream.next_out = (Bytef *)png_ptr->zbuf;
 212
 213    /* this is the same compression loop as in png_write_row() */
 214    do
 215    {
 216       /* compress the data */
 217       ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
 218       if (ret != Z_OK)
 219       {
 220          /* error */
 221          if (png_ptr->zstream.msg != NULL)
 222             png_error(png_ptr, png_ptr->zstream.msg);
 223          else
 224             png_error(png_ptr, "zlib error");
 225       }
 226       /* check to see if we need more room */
 227       if (!(png_ptr->zstream.avail_out))
 228       {
 229          /* make sure the output array has room */
 230          if (comp->num_output_ptr >= comp->max_output_ptr)
 231          {
 232             int old_max;
 233
 234             old_max = comp->max_output_ptr;
 235             comp->max_output_ptr = comp->num_output_ptr + 4;
 236             if (comp->output_ptr != NULL)
 237             {
 238                png_charpp old_ptr;
 239
 240                old_ptr = comp->output_ptr;
 241                comp->output_ptr = (png_charpp)png_malloc(png_ptr,
 242                   (png_uint_32)(comp->max_output_ptr *
 243                   png_sizeof (png_charpp)));
 244                png_memcpy(comp->output_ptr, old_ptr, old_max
 245                   * png_sizeof (png_charp));
 246                png_free(png_ptr, old_ptr);
 247             }
 248             else
 249                comp->output_ptr = (png_charpp)png_malloc(png_ptr,
 250                   (png_uint_32)(comp->max_output_ptr *
 251                   png_sizeof (png_charp)));
 252          }
 253
 254          /* save the data */
 255          comp->output_ptr[comp->num_output_ptr] = (png_charp)png_malloc(png_ptr,
 256             (png_uint_32)png_ptr->zbuf_size);
 257          png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
 258             png_ptr->zbuf_size);
 259          comp->num_output_ptr++;
 260
 261          /* and reset the buffer */
 262          png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
 263          png_ptr->zstream.next_out = png_ptr->zbuf;
 264       }
 265    /* continue until we don't have any more to compress */
 266    } while (png_ptr->zstream.avail_in);
 267
 268    /* finish the compression */
 269    do
 270    {
 271       /* tell zlib we are finished */
 272       ret = deflate(&png_ptr->zstream, Z_FINISH);
 273
 274       if (ret == Z_OK)
 275       {
 276          /* check to see if we need more room */
 277          if (!(png_ptr->zstream.avail_out))
 278          {
 279             /* check to make sure our output array has room */
 280             if (comp->num_output_ptr >= comp->max_output_ptr)
 281             {
 282                int old_max;
 283
 284                old_max = comp->max_output_ptr;
 285                comp->max_output_ptr = comp->num_output_ptr + 4;
 286                if (comp->output_ptr != NULL)
 287                {
 288                   png_charpp old_ptr;
 289
 290                   old_ptr = comp->output_ptr;
 291                   /* This could be optimized to realloc() */
 292                   comp->output_ptr = (png_charpp)png_malloc(png_ptr,
 293                      (png_uint_32)(comp->max_output_ptr *
 294                      png_sizeof (png_charpp)));
 295                   png_memcpy(comp->output_ptr, old_ptr,
 296                      old_max * png_sizeof (png_charp));
 297                   png_free(png_ptr, old_ptr);
 298                }
 299                else
 300                   comp->output_ptr = (png_charpp)png_malloc(png_ptr,
 301                      (png_uint_32)(comp->max_output_ptr *
 302                      png_sizeof (png_charp)));
 303             }
 304
 305             /* save off the data */
 306             comp->output_ptr[comp->num_output_ptr] =
 307                (png_charp)png_malloc(png_ptr, (png_uint_32)png_ptr->zbuf_size);
 308             png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
 309                png_ptr->zbuf_size);
 310             comp->num_output_ptr++;
 311
 312             /* and reset the buffer pointers */
 313             png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
 314             png_ptr->zstream.next_out = png_ptr->zbuf;
 315          }
 316       }
 317       else if (ret != Z_STREAM_END)
 318       {
 319          /* we got an error */
 320          if (png_ptr->zstream.msg != NULL)
 321             png_error(png_ptr, png_ptr->zstream.msg);
 322          else
 323             png_error(png_ptr, "zlib error");
 324       }
 325    } while (ret != Z_STREAM_END);
 326
 327    /* text length is number of buffers plus last buffer */
 328    text_len = png_ptr->zbuf_size * comp->num_output_ptr;
 329    if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
 330       text_len += png_ptr->zbuf_size - (png_size_t)png_ptr->zstream.avail_out;
 331
 332    return((int)text_len);
 333 }
 334
 335 /* ship the compressed text out via chunk writes */
 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_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_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_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_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_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_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_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_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_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_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_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_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_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_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_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_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_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_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_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 ((png_byte)*kp < 0x20 ||
1235          ((png_byte)*kp > 0x7E && (png_byte)*kp < 0xA1))
1236       {
1237 #if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
1238          char msg[40];
1239
1240          png_snprintf(msg, 40,
1241            "invalid keyword character 0x%02X", (png_byte)*kp);
1242          png_warning(png_ptr, msg);
1243 #else
1244          png_warning(png_ptr, "invalid character in keyword");
1245 #endif
1246          *dp = ' ';
1247       }
1248       else
1249       {
1250          *dp = *kp;
1251       }
1252    }
1253    *dp = '\0';
1254
1255    /* Remove any trailing white space. */
1256    kp = *new_key + key_len - 1;
1257    if (*kp == ' ')
1258    {
1259       png_warning(png_ptr, "trailing spaces removed from keyword");
1260
1261       while (*kp == ' ')
1262       {
1263         *(kp--) = '\0';
1264         key_len--;
1265       }
1266    }
1267
1268    /* Remove any leading white space. */
1269    kp = *new_key;
1270    if (*kp == ' ')
1271    {
1272       png_warning(png_ptr, "leading spaces removed from keyword");
1273
1274       while (*kp == ' ')
1275       {
1276         kp++;
1277         key_len--;
1278       }
1279    }
1280
1281    png_debug1(2, "Checking for multiple internal spaces in '%s'\n", kp);
1282
1283    /* Remove multiple internal spaces. */
1284    for (kflag = 0, dp = *new_key; *kp != '\0'; kp++)
1285    {
1286       if (*kp == ' ' && kflag == 0)
1287       {
1288          *(dp++) = *kp;
1289          kflag = 1;
1290       }
1291       else if (*kp == ' ')
1292       {
1293          key_len--;
1294          kwarn=1;
1295       }
1296       else
1297       {
1298          *(dp++) = *kp;
1299          kflag = 0;
1300       }
1301    }
1302    *dp = '\0';
1303    if(kwarn)
1304       png_warning(png_ptr, "extra interior spaces removed from keyword");
1305
1306    if (key_len == 0)
1307    {
1308       png_free(png_ptr, *new_key);
1309       *new_key=NULL;
1310       png_warning(png_ptr, "Zero length keyword");
1311    }
1312
1313    if (key_len > 79)
1314    {
1315       png_warning(png_ptr, "keyword length must be 1 - 79 characters");
1316       new_key[79] = '\0';
1317       key_len = 79;
1318    }
1319
1320    return (key_len);
1321 }
1322 #endif
1323
1324 #if defined(PNG_WRITE_tEXt_SUPPORTED)
1325 /* write a tEXt chunk */
1326 void /* PRIVATE */
1327 png_write_tEXt(png_structp png_ptr, png_charp key, png_charp text,
1328    png_size_t text_len)
1329 {
1330 #ifdef PNG_USE_LOCAL_ARRAYS
1331    PNG_tEXt;
1332 #endif
1333    png_size_t key_len;
1334    png_charp new_key;
1335
1336    png_debug(1, "in png_write_tEXt\n");
1337    if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0)
1338    {
1339       png_warning(png_ptr, "Empty keyword in tEXt chunk");
1340       return;
1341    }
1342
1343    if (text == NULL || *text == '\0')
1344       text_len = 0;
1345    else
1346       text_len = png_strlen(text);
1347
1348    /* make sure we include the 0 after the key */
1349    png_write_chunk_start(png_ptr, png_tEXt, (png_uint_32)key_len+text_len+1);
1350    /*
1351     * We leave it to the application to meet PNG-1.0 requirements on the
1352     * contents of the text.  PNG-1.0 through PNG-1.2 discourage the use of
1353     * any non-Latin-1 characters except for NEWLINE.  ISO PNG will forbid them.
1354     * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1355     */
1356    png_write_chunk_data(png_ptr, (png_bytep)new_key, key_len + 1);
1357    if (text_len)
1358       png_write_chunk_data(png_ptr, (png_bytep)text, text_len);
1359
1360    png_write_chunk_end(png_ptr);
1361    png_free(png_ptr, new_key);
1362 }
1363 #endif
1364
1365 #if defined(PNG_WRITE_zTXt_SUPPORTED)
1366 /* write a compressed text chunk */
1367 void /* PRIVATE */
1368 png_write_zTXt(png_structp png_ptr, png_charp key, png_charp text,
1369    png_size_t text_len, int compression)
1370 {
1371 #ifdef PNG_USE_LOCAL_ARRAYS
1372    PNG_zTXt;
1373 #endif
1374    png_size_t key_len;
1375    char buf[1];
1376    png_charp new_key;
1377    compression_state comp;
1378
1379    png_debug(1, "in png_write_zTXt\n");
1380
1381    comp.num_output_ptr = 0;
1382    comp.max_output_ptr = 0;
1383    comp.output_ptr = NULL;
1384    comp.input = NULL;
1385    comp.input_len = 0;
1386
1387    if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0)
1388    {
1389       png_warning(png_ptr, "Empty keyword in zTXt chunk");
1390       return;
1391    }
1392
1393    if (text == NULL || *text == '\0' || compression==PNG_TEXT_COMPRESSION_NONE)
1394    {
1395       png_write_tEXt(png_ptr, new_key, text, (png_size_t)0);
1396       png_free(png_ptr, new_key);
1397       return;
1398    }
1399
1400    text_len = png_strlen(text);
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_zTXt, (png_uint_32)
1408       (key_len+text_len+2));
1409    /* write key */
1410    png_write_chunk_data(png_ptr, (png_bytep)new_key, key_len + 1);
1411    png_free(png_ptr, new_key);
1412
1413    buf[0] = (png_byte)compression;
1414    /* write compression */
1415    png_write_chunk_data(png_ptr, (png_bytep)buf, (png_size_t)1);
1416    /* write the compressed data */
1417    png_write_compressed_data_out(png_ptr, &comp);
1418
1419    /* close the chunk */
1420    png_write_chunk_end(png_ptr);
1421 }
1422 #endif
1423
1424 #if defined(PNG_WRITE_iTXt_SUPPORTED)
1425 /* write an iTXt chunk */
1426 void /* PRIVATE */
1427 png_write_iTXt(png_structp png_ptr, int compression, png_charp key,
1428     png_charp lang, png_charp lang_key, png_charp text)
1429 {
1430 #ifdef PNG_USE_LOCAL_ARRAYS
1431    PNG_iTXt;
1432 #endif
1433    png_size_t lang_len, key_len, lang_key_len, text_len;
1434    png_charp new_lang, new_key;
1435    png_byte cbuf[2];
1436    compression_state comp;
1437
1438    png_debug(1, "in png_write_iTXt\n");
1439
1440    comp.num_output_ptr = 0;
1441    comp.max_output_ptr = 0;
1442    comp.output_ptr = NULL;
1443    comp.input = NULL;
1444
1445    if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0)
1446    {
1447       png_warning(png_ptr, "Empty keyword in iTXt chunk");
1448       return;
1449    }
1450    if (lang == NULL || (lang_len = png_check_keyword(png_ptr, lang, &new_lang))==0)
1451    {
1452       png_warning(png_ptr, "Empty language field in iTXt chunk");
1453       new_lang = NULL;
1454       lang_len = 0;
1455    }
1456
1457    if (lang_key == NULL)
1458      lang_key_len = 0;
1459    else
1460      lang_key_len = png_strlen(lang_key);
1461
1462    if (text == NULL)
1463       text_len = 0;
1464    else
1465      text_len = png_strlen(text);
1466
1467    /* compute the compressed data; do it now for the length */
1468    text_len = png_text_compress(png_ptr, text, text_len, compression-2,
1469       &comp);
1470
1471
1472    /* make sure we include the compression flag, the compression byte,
1473     * and the NULs after the key, lang, and lang_key parts */
1474
1475    png_write_chunk_start(png_ptr, png_iTXt,
1476           (png_uint_32)(
1477         5 /* comp byte, comp flag, terminators for key, lang and lang_key */
1478         + key_len
1479         + lang_len
1480         + lang_key_len
1481         + text_len));
1482
1483    /*
1484     * We leave it to the application to meet PNG-1.0 requirements on the
1485     * contents of the text.  PNG-1.0 through PNG-1.2 discourage the use of
1486     * any non-Latin-1 characters except for NEWLINE.  ISO PNG will forbid them.
1487     * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
1488     */
1489    png_write_chunk_data(png_ptr, (png_bytep)new_key, key_len + 1);
1490
1491    /* set the compression flag */
1492    if (compression == PNG_ITXT_COMPRESSION_NONE || \
1493        compression == PNG_TEXT_COMPRESSION_NONE)
1494        cbuf[0] = 0;
1495    else /* compression == PNG_ITXT_COMPRESSION_zTXt */
1496        cbuf[0] = 1;
1497    /* set the compression method */
1498    cbuf[1] = 0;
1499    png_write_chunk_data(png_ptr, cbuf, 2);
1500
1501    cbuf[0] = 0;
1502    png_write_chunk_data(png_ptr, (new_lang ? (png_bytep)new_lang : cbuf), lang_len + 1);
1503    png_write_chunk_data(png_ptr, (lang_key ? (png_bytep)lang_key : cbuf), lang_key_len + 1);
1504    png_write_compressed_data_out(png_ptr, &comp);
1505
1506    png_write_chunk_end(png_ptr);
1507    png_free(png_ptr, new_key);
1508    if (new_lang)
1509      png_free(png_ptr, new_lang);
1510 }
1511 #endif
1512
1513 #if defined(PNG_WRITE_oFFs_SUPPORTED)
1514 /* write the oFFs chunk */
1515 void /* PRIVATE */
1516 png_write_oFFs(png_structp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
1517    int unit_type)
1518 {
1519 #ifdef PNG_USE_LOCAL_ARRAYS
1520    PNG_oFFs;
1521 #endif
1522    png_byte buf[9];
1523
1524    png_debug(1, "in png_write_oFFs\n");
1525    if (unit_type >= PNG_OFFSET_LAST)
1526       png_warning(png_ptr, "Unrecognized unit type for oFFs chunk");
1527
1528    png_save_int_32(buf, x_offset);
1529    png_save_int_32(buf + 4, y_offset);
1530    buf[8] = (png_byte)unit_type;
1531
1532    png_write_chunk(png_ptr, png_oFFs, buf, (png_size_t)9);
1533 }
1534 #endif
1535 #if defined(PNG_WRITE_pCAL_SUPPORTED)
1536 /* write the pCAL chunk (described in the PNG extensions document) */
1537 void /* PRIVATE */
1538 png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
1539    png_int_32 X1, int type, int nparams, png_charp units, png_charpp params)
1540 {
1541 #ifdef PNG_USE_LOCAL_ARRAYS
1542    PNG_pCAL;
1543 #endif
1544    png_size_t purpose_len, units_len, total_len;
1545    png_uint_32p params_len;
1546    png_byte buf[10];
1547    png_charp new_purpose;
1548    int i;
1549
1550    png_debug1(1, "in png_write_pCAL (%d parameters)\n", nparams);
1551    if (type >= PNG_EQUATION_LAST)
1552       png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");
1553
1554    purpose_len = png_check_keyword(png_ptr, purpose, &new_purpose) + 1;
1555    png_debug1(3, "pCAL purpose length = %d\n", (int)purpose_len);
1556    units_len = png_strlen(units) + (nparams == 0 ? 0 : 1);
1557    png_debug1(3, "pCAL units length = %d\n", (int)units_len);
1558    total_len = purpose_len + units_len + 10;
1559
1560    params_len = (png_uint_32p)png_malloc(png_ptr, (png_uint_32)(nparams
1561       *png_sizeof(png_uint_32)));
1562
1563    /* Find the length of each parameter, making sure we don't count the
1564       null terminator for the last parameter. */
1565    for (i = 0; i < nparams; i++)
1566    {
1567       params_len[i] = png_strlen(params[i]) + (i == nparams - 1 ? 0 : 1);
1568       png_debug2(3, "pCAL parameter %d length = %lu\n", i, params_len[i]);
1569       total_len += (png_size_t)params_len[i];
1570    }
1571
1572    png_debug1(3, "pCAL total length = %d\n", (int)total_len);
1573    png_write_chunk_start(png_ptr, png_pCAL, (png_uint_32)total_len);
1574    png_write_chunk_data(png_ptr, (png_bytep)new_purpose, purpose_len);
1575    png_save_int_32(buf, X0);
1576    png_save_int_32(buf + 4, X1);
1577    buf[8] = (png_byte)type;
1578    buf[9] = (png_byte)nparams;
1579    png_write_chunk_data(png_ptr, buf, (png_size_t)10);
1580    png_write_chunk_data(png_ptr, (png_bytep)units, (png_size_t)units_len);
1581
1582    png_free(png_ptr, new_purpose);
1583
1584    for (i = 0; i < nparams; i++)
1585    {
1586       png_write_chunk_data(png_ptr, (png_bytep)params[i],
1587          (png_size_t)params_len[i]);
1588    }
1589
1590    png_free(png_ptr, params_len);
1591    png_write_chunk_end(png_ptr);
1592 }
1593 #endif
1594
1595 #if defined(PNG_WRITE_sCAL_SUPPORTED)
1596 /* write the sCAL chunk */
1597 #if defined(PNG_FLOATING_POINT_SUPPORTED) && !defined(PNG_NO_STDIO)
1598 void /* PRIVATE */
1599 png_write_sCAL(png_structp png_ptr, int unit, double width, double height)
1600 {
1601 #ifdef PNG_USE_LOCAL_ARRAYS
1602    PNG_sCAL;
1603 #endif
1604    char buf[64];
1605    png_size_t total_len;
1606
1607    png_debug(1, "in png_write_sCAL\n");
1608
1609    buf[0] = (char)unit;
1610 #if defined(_WIN32_WCE)
1611 /* sprintf() function is not supported on WindowsCE */
1612    {
1613       wchar_t wc_buf[32];
1614       size_t wc_len;
1615       swprintf(wc_buf, TEXT("%12.12e"), width);
1616       wc_len = wcslen(wc_buf);
1617       WideCharToMultiByte(CP_ACP, 0, wc_buf, -1, buf + 1, wc_len, NULL, NULL);
1618       total_len = wc_len + 2;
1619       swprintf(wc_buf, TEXT("%12.12e"), height);
1620       wc_len = wcslen(wc_buf);
1621       WideCharToMultiByte(CP_ACP, 0, wc_buf, -1, buf + total_len, wc_len,
1622          NULL, NULL);
1623       total_len += wc_len;
1624    }
1625 #else
1626    png_snprintf(buf + 1, 63, "%12.12e", width);
1627    total_len = 1 + png_strlen(buf + 1) + 1;
1628    png_snprintf(buf + total_len, 64-total_len, "%12.12e", height);
1629    total_len += png_strlen(buf + total_len);
1630 #endif
1631
1632    png_debug1(3, "sCAL total length = %u\n", (unsigned int)total_len);
1633    png_write_chunk(png_ptr, png_sCAL, (png_bytep)buf, total_len);
1634 }
1635 #else
1636 #ifdef PNG_FIXED_POINT_SUPPORTED
1637 void /* PRIVATE */
1638 png_write_sCAL_s(png_structp png_ptr, int unit, png_charp width,
1639    png_charp height)
1640 {
1641 #ifdef PNG_USE_LOCAL_ARRAYS
1642    PNG_sCAL;
1643 #endif
1644    png_byte buf[64];
1645    png_size_t wlen, hlen, total_len;
1646
1647    png_debug(1, "in png_write_sCAL_s\n");
1648
1649    wlen = png_strlen(width);
1650    hlen = png_strlen(height);
1651    total_len = wlen + hlen + 2;
1652    if (total_len > 64)
1653    {
1654       png_warning(png_ptr, "Can't write sCAL (buffer too small)");
1655       return;
1656    }
1657
1658    buf[0] = (png_byte)unit;
1659    png_memcpy(buf + 1, width, wlen + 1);      /* append the '\0' here */
1660    png_memcpy(buf + wlen + 2, height, hlen);  /* do NOT append the '\0' here */
1661
1662    png_debug1(3, "sCAL total length = %u\n", (unsigned int)total_len);
1663    png_write_chunk(png_ptr, png_sCAL, buf, total_len);
1664 }
1665 #endif
1666 #endif
1667 #endif
1668
1669 #if defined(PNG_WRITE_pHYs_SUPPORTED)
1670 /* write the pHYs chunk */
1671 void /* PRIVATE */
1672 png_write_pHYs(png_structp png_ptr, png_uint_32 x_pixels_per_unit,
1673    png_uint_32 y_pixels_per_unit,
1674    int unit_type)
1675 {
1676 #ifdef PNG_USE_LOCAL_ARRAYS
1677    PNG_pHYs;
1678 #endif
1679    png_byte buf[9];
1680
1681    png_debug(1, "in png_write_pHYs\n");
1682    if (unit_type >= PNG_RESOLUTION_LAST)
1683       png_warning(png_ptr, "Unrecognized unit type for pHYs chunk");
1684
1685    png_save_uint_32(buf, x_pixels_per_unit);
1686    png_save_uint_32(buf + 4, y_pixels_per_unit);
1687    buf[8] = (png_byte)unit_type;
1688
1689    png_write_chunk(png_ptr, png_pHYs, buf, (png_size_t)9);
1690 }
1691 #endif
1692
1693 #if defined(PNG_WRITE_tIME_SUPPORTED)
1694 /* Write the tIME chunk.  Use either png_convert_from_struct_tm()
1695  * or png_convert_from_time_t(), or fill in the structure yourself.
1696  */
1697 void /* PRIVATE */
1698 png_write_tIME(png_structp png_ptr, png_timep mod_time)
1699 {
1700 #ifdef PNG_USE_LOCAL_ARRAYS
1701    PNG_tIME;
1702 #endif
1703    png_byte buf[7];
1704
1705    png_debug(1, "in png_write_tIME\n");
1706    if (mod_time->month  > 12 || mod_time->month  < 1 ||
1707        mod_time->day    > 31 || mod_time->day    < 1 ||
1708        mod_time->hour   > 23 || mod_time->second > 60)
1709    {
1710       png_warning(png_ptr, "Invalid time specified for tIME chunk");
1711       return;
1712    }
1713
1714    png_save_uint_16(buf, mod_time->year);
1715    buf[2] = mod_time->month;
1716    buf[3] = mod_time->day;
1717    buf[4] = mod_time->hour;
1718    buf[5] = mod_time->minute;
1719    buf[6] = mod_time->second;
1720
1721    png_write_chunk(png_ptr, png_tIME, buf, (png_size_t)7);
1722 }
1723 #endif
1724
1725 /* initializes the row writing capability of libpng */
1726 void /* PRIVATE */
1727 png_write_start_row(png_structp png_ptr)
1728 {
1729 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
1730 #ifdef PNG_USE_LOCAL_ARRAYS
1731    /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1732
1733    /* start of interlace block */
1734    int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
1735
1736    /* offset to next interlace block */
1737    int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
1738
1739    /* start of interlace block in the y direction */
1740    int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
1741
1742    /* offset to next interlace block in the y direction */
1743    int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
1744 #endif
1745 #endif
1746
1747    png_size_t buf_size;
1748
1749    png_debug(1, "in png_write_start_row\n");
1750    buf_size = (png_size_t)(PNG_ROWBYTES(
1751       png_ptr->usr_channels*png_ptr->usr_bit_depth,png_ptr->width)+1);
1752
1753    /* set up row buffer */
1754    png_ptr->row_buf = (png_bytep)png_malloc(png_ptr, (png_uint_32)buf_size);
1755    png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE;
1756
1757 #ifndef PNG_NO_WRITE_FILTERING
1758    /* set up filtering buffer, if using this filter */
1759    if (png_ptr->do_filter & PNG_FILTER_SUB)
1760    {
1761       png_ptr->sub_row = (png_bytep)png_malloc(png_ptr,
1762          (png_ptr->rowbytes + 1));
1763       png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
1764    }
1765
1766    /* We only need to keep the previous row if we are using one of these. */
1767    if (png_ptr->do_filter & (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH))
1768    {
1769      /* set up previous row buffer */
1770       png_ptr->prev_row = (png_bytep)png_malloc(png_ptr, (png_uint_32)buf_size);
1771       png_memset(png_ptr->prev_row, 0, buf_size);
1772
1773       if (png_ptr->do_filter & PNG_FILTER_UP)
1774       {
1775          png_ptr->up_row = (png_bytep)png_malloc(png_ptr,
1776             (png_ptr->rowbytes + 1));
1777          png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;
1778       }
1779
1780       if (png_ptr->do_filter & PNG_FILTER_AVG)
1781       {
1782          png_ptr->avg_row = (png_bytep)png_malloc(png_ptr,
1783             (png_ptr->rowbytes + 1));
1784          png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;
1785       }
1786
1787       if (png_ptr->do_filter & PNG_FILTER_PAETH)
1788       {
1789          png_ptr->paeth_row = (png_bytep)png_malloc(png_ptr,
1790             (png_ptr->rowbytes + 1));
1791          png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
1792       }
1793 #endif /* PNG_NO_WRITE_FILTERING */
1794    }
1795
1796 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
1797    /* if interlaced, we need to set up width and height of pass */
1798    if (png_ptr->interlaced)
1799    {
1800       if (!(png_ptr->transformations & PNG_INTERLACE))
1801       {
1802          png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
1803             png_pass_ystart[0]) / png_pass_yinc[0];
1804          png_ptr->usr_width = (png_ptr->width + png_pass_inc[0] - 1 -
1805             png_pass_start[0]) / png_pass_inc[0];
1806       }
1807       else
1808       {
1809          png_ptr->num_rows = png_ptr->height;
1810          png_ptr->usr_width = png_ptr->width;
1811       }
1812    }
1813    else
1814 #endif
1815    {
1816       png_ptr->num_rows = png_ptr->height;
1817       png_ptr->usr_width = png_ptr->width;
1818    }
1819    png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1820    png_ptr->zstream.next_out = png_ptr->zbuf;
1821 }
1822
1823 /* Internal use only.  Called when finished processing a row of data. */
1824 void /* PRIVATE */
1825 png_write_finish_row(png_structp png_ptr)
1826 {
1827 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
1828 #ifdef PNG_USE_LOCAL_ARRAYS
1829    /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1830
1831    /* start of interlace block */
1832    int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
1833
1834    /* offset to next interlace block */
1835    int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
1836
1837    /* start of interlace block in the y direction */
1838    int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
1839
1840    /* offset to next interlace block in the y direction */
1841    int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
1842 #endif
1843 #endif
1844
1845    int ret;
1846
1847    png_debug(1, "in png_write_finish_row\n");
1848    /* next row */
1849    png_ptr->row_number++;
1850
1851    /* see if we are done */
1852    if (png_ptr->row_number < png_ptr->num_rows)
1853       return;
1854
1855 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
1856    /* if interlaced, go to next pass */
1857    if (png_ptr->interlaced)
1858    {
1859       png_ptr->row_number = 0;
1860       if (png_ptr->transformations & PNG_INTERLACE)
1861       {
1862          png_ptr->pass++;
1863       }
1864       else
1865       {
1866          /* loop until we find a non-zero width or height pass */
1867          do
1868          {
1869             png_ptr->pass++;
1870             if (png_ptr->pass >= 7)
1871                break;
1872             png_ptr->usr_width = (png_ptr->width +
1873                png_pass_inc[png_ptr->pass] - 1 -
1874                png_pass_start[png_ptr->pass]) /
1875                png_pass_inc[png_ptr->pass];
1876             png_ptr->num_rows = (png_ptr->height +
1877                png_pass_yinc[png_ptr->pass] - 1 -
1878                png_pass_ystart[png_ptr->pass]) /
1879                png_pass_yinc[png_ptr->pass];
1880             if (png_ptr->transformations & PNG_INTERLACE)
1881                break;
1882          } while (png_ptr->usr_width == 0 || png_ptr->num_rows == 0);
1883
1884       }
1885
1886       /* reset the row above the image for the next pass */
1887       if (png_ptr->pass < 7)
1888       {
1889          if (png_ptr->prev_row != NULL)
1890             png_memset(png_ptr->prev_row, 0,
1891                (png_size_t)(PNG_ROWBYTES(png_ptr->usr_channels*
1892                png_ptr->usr_bit_depth,png_ptr->width))+1);
1893          return;
1894       }
1895    }
1896 #endif
1897
1898    /* if we get here, we've just written the last row, so we need
1899       to flush the compressor */
1900    do
1901    {
1902       /* tell the compressor we are done */
1903       ret = deflate(&png_ptr->zstream, Z_FINISH);
1904       /* check for an error */
1905       if (ret == Z_OK)
1906       {
1907          /* check to see if we need more room */
1908          if (!(png_ptr->zstream.avail_out))
1909          {
1910             png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
1911             png_ptr->zstream.next_out = png_ptr->zbuf;
1912             png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
1913          }
1914       }
1915       else if (ret != Z_STREAM_END)
1916       {
1917          if (png_ptr->zstream.msg != NULL)
1918             png_error(png_ptr, png_ptr->zstream.msg);
1919          else
1920             png_error(png_ptr, "zlib error");
1921       }
1922    } while (ret != Z_STREAM_END);
1923
1924    /* write any extra space */
1925    if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
1926    {
1927       png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size -
1928          png_ptr->zstream.avail_out);
1929    }
1930
1931    deflateReset(&png_ptr->zstream);
1932    png_ptr->zstream.data_type = Z_BINARY;
1933 }
1934
1935 #if defined(PNG_WRITE_INTERLACING_SUPPORTED)
1936 /* Pick out the correct pixels for the interlace pass.
1937  * The basic idea here is to go through the row with a source
1938  * pointer and a destination pointer (sp and dp), and copy the
1939  * correct pixels for the pass.  As the row gets compacted,
1940  * sp will always be >= dp, so we should never overwrite anything.
1941  * See the default: case for the easiest code to understand.
1942  */
1943 void /* PRIVATE */
1944 png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
1945 {
1946 #ifdef PNG_USE_LOCAL_ARRAYS
1947    /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
1948
1949    /* start of interlace block */
1950    int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
1951
1952    /* offset to next interlace block */
1953    int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
1954 #endif
1955
1956    png_debug(1, "in png_do_write_interlace\n");
1957    /* we don't have to do anything on the last pass (6) */
1958 #if defined(PNG_USELESS_TESTS_SUPPORTED)
1959    if (row != NULL && row_info != NULL && pass < 6)
1960 #else
1961    if (pass < 6)
1962 #endif
1963    {
1964       /* each pixel depth is handled separately */
1965       switch (row_info->pixel_depth)
1966       {
1967          case 1:
1968          {
1969             png_bytep sp;
1970             png_bytep dp;
1971             int shift;
1972             int d;
1973             int value;
1974             png_uint_32 i;
1975             png_uint_32 row_width = row_info->width;
1976
1977             dp = row;
1978             d = 0;
1979             shift = 7;
1980             for (i = png_pass_start[pass]; i < row_width;
1981                i += png_pass_inc[pass])
1982             {
1983                sp = row + (png_size_t)(i >> 3);
1984                value = (int)(*sp >> (7 - (int)(i & 0x07))) & 0x01;
1985                d |= (value << shift);
1986
1987                if (shift == 0)
1988                {
1989                   shift = 7;
1990                   *dp++ = (png_byte)d;
1991                   d = 0;
1992                }
1993                else
1994                   shift--;
1995
1996             }
1997             if (shift != 7)
1998                *dp = (png_byte)d;
1999             break;
2000          }
2001          case 2:
2002          {
2003             png_bytep sp;
2004             png_bytep dp;
2005             int shift;
2006             int d;
2007             int value;
2008             png_uint_32 i;
2009             png_uint_32 row_width = row_info->width;
2010
2011             dp = row;
2012             shift = 6;
2013             d = 0;
2014             for (i = png_pass_start[pass]; i < row_width;
2015                i += png_pass_inc[pass])
2016             {
2017                sp = row + (png_size_t)(i >> 2);
2018                value = (*sp >> ((3 - (int)(i & 0x03)) << 1)) & 0x03;
2019                d |= (value << shift);
2020
2021                if (shift == 0)
2022                {
2023                   shift = 6;
2024                   *dp++ = (png_byte)d;
2025                   d = 0;
2026                }
2027                else
2028                   shift -= 2;
2029             }
2030             if (shift != 6)
2031                    *dp = (png_byte)d;
2032             break;
2033          }
2034          case 4:
2035          {
2036             png_bytep sp;
2037             png_bytep dp;
2038             int shift;
2039             int d;
2040             int value;
2041             png_uint_32 i;
2042             png_uint_32 row_width = row_info->width;
2043
2044             dp = row;
2045             shift = 4;
2046             d = 0;
2047             for (i = png_pass_start[pass]; i < row_width;
2048                i += png_pass_inc[pass])
2049             {
2050                sp = row + (png_size_t)(i >> 1);
2051                value = (*sp >> ((1 - (int)(i & 0x01)) << 2)) & 0x0f;
2052                d |= (value << shift);
2053
2054                if (shift == 0)
2055                {
2056                   shift = 4;
2057                   *dp++ = (png_byte)d;
2058                   d = 0;
2059                }
2060                else
2061                   shift -= 4;
2062             }
2063             if (shift != 4)
2064                *dp = (png_byte)d;
2065             break;
2066          }
2067          default:
2068          {
2069             png_bytep sp;
2070             png_bytep dp;
2071             png_uint_32 i;
2072             png_uint_32 row_width = row_info->width;
2073             png_size_t pixel_bytes;
2074
2075             /* start at the beginning */
2076             dp = row;
2077             /* find out how many bytes each pixel takes up */
2078             pixel_bytes = (row_info->pixel_depth >> 3);
2079             /* loop through the row, only looking at the pixels that
2080                matter */
2081             for (i = png_pass_start[pass]; i < row_width;
2082                i += png_pass_inc[pass])
2083             {
2084                /* find out where the original pixel is */
2085                sp = row + (png_size_t)i * pixel_bytes;
2086                /* move the pixel */
2087                if (dp != sp)
2088                   png_memcpy(dp, sp, pixel_bytes);
2089                /* next pixel */
2090                dp += pixel_bytes;
2091             }
2092             break;
2093          }
2094       }
2095       /* set new row width */
2096       row_info->width = (row_info->width +
2097          png_pass_inc[pass] - 1 -
2098          png_pass_start[pass]) /
2099          png_pass_inc[pass];
2100          row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
2101             row_info->width);
2102    }
2103 }
2104 #endif
2105
2106 /* This filters the row, chooses which filter to use, if it has not already
2107  * been specified by the application, and then writes the row out with the
2108  * chosen filter.
2109  */
2110 #define PNG_MAXSUM (((png_uint_32)(-1)) >> 1)
2111 #define PNG_HISHIFT 10
2112 #define PNG_LOMASK ((png_uint_32)0xffffL)
2113 #define PNG_HIMASK ((png_uint_32)(~PNG_LOMASK >> PNG_HISHIFT))
2114 void /* PRIVATE */
2115 png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
2116 {
2117    png_bytep best_row;
2118 #ifndef PNG_NO_WRITE_FILTER
2119    png_bytep prev_row, row_buf;
2120    png_uint_32 mins, bpp;
2121    png_byte filter_to_do = png_ptr->do_filter;
2122    png_uint_32 row_bytes = row_info->rowbytes;
2123 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2124    int num_p_filters = (int)png_ptr->num_prev_filters;
2125 #endif
2126
2127    png_debug(1, "in png_write_find_filter\n");
2128    /* find out how many bytes offset each pixel is */
2129    bpp = (row_info->pixel_depth + 7) >> 3;
2130
2131    prev_row = png_ptr->prev_row;
2132 #endif
2133    best_row = png_ptr->row_buf;
2134 #ifndef PNG_NO_WRITE_FILTER
2135    row_buf = best_row;
2136    mins = PNG_MAXSUM;
2137
2138    /* The prediction method we use is to find which method provides the
2139     * smallest value when summing the absolute values of the distances
2140     * from zero, using anything >= 128 as negative numbers.  This is known
2141     * as the "minimum sum of absolute differences" heuristic.  Other
2142     * heuristics are the "weighted minimum sum of absolute differences"
2143     * (experimental and can in theory improve compression), and the "zlib
2144     * predictive" method (not implemented yet), which does test compressions
2145     * of lines using different filter methods, and then chooses the
2146     * (series of) filter(s) that give minimum compressed data size (VERY
2147     * computationally expensive).
2148     *
2149     * GRR 980525:  consider also
2150     *   (1) minimum sum of absolute differences from running average (i.e.,
2151     *       keep running sum of non-absolute differences & count of bytes)
2152     *       [track dispersion, too?  restart average if dispersion too large?]
2153     *  (1b) minimum sum of absolute differences from sliding average, probably
2154     *       with window size <= deflate window (usually 32K)
2155     *   (2) minimum sum of squared differences from zero or running average
2156     *       (i.e., ~ root-mean-square approach)
2157     */
2158
2159
2160    /* We don't need to test the 'no filter' case if this is the only filter
2161     * that has been chosen, as it doesn't actually do anything to the data.
2162     */
2163    if ((filter_to_do & PNG_FILTER_NONE) &&
2164        filter_to_do != PNG_FILTER_NONE)
2165    {
2166       png_bytep rp;
2167       png_uint_32 sum = 0;
2168       png_uint_32 i;
2169       int v;
2170
2171       for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
2172       {
2173          v = *rp;
2174          sum += (v < 128) ? v : 256 - v;
2175       }
2176
2177 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2178       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2179       {
2180          png_uint_32 sumhi, sumlo;
2181          int j;
2182          sumlo = sum & PNG_LOMASK;
2183          sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; /* Gives us some footroom */
2184
2185          /* Reduce the sum if we match any of the previous rows */
2186          for (j = 0; j < num_p_filters; j++)
2187          {
2188             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
2189             {
2190                sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2191                   PNG_WEIGHT_SHIFT;
2192                sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2193                   PNG_WEIGHT_SHIFT;
2194             }
2195          }
2196
2197          /* Factor in the cost of this filter (this is here for completeness,
2198           * but it makes no sense to have a "cost" for the NONE filter, as
2199           * it has the minimum possible computational cost - none).
2200           */
2201          sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
2202             PNG_COST_SHIFT;
2203          sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
2204             PNG_COST_SHIFT;
2205
2206          if (sumhi > PNG_HIMASK)
2207             sum = PNG_MAXSUM;
2208          else
2209             sum = (sumhi << PNG_HISHIFT) + sumlo;
2210       }
2211 #endif
2212       mins = sum;
2213    }
2214
2215    /* sub filter */
2216    if (filter_to_do == PNG_FILTER_SUB)
2217    /* it's the only filter so no testing is needed */
2218    {
2219       png_bytep rp, lp, dp;
2220       png_uint_32 i;
2221       for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
2222            i++, rp++, dp++)
2223       {
2224          *dp = *rp;
2225       }
2226       for (lp = row_buf + 1; i < row_bytes;
2227          i++, rp++, lp++, dp++)
2228       {
2229          *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
2230       }
2231       best_row = png_ptr->sub_row;
2232    }
2233
2234    else if (filter_to_do & PNG_FILTER_SUB)
2235    {
2236       png_bytep rp, dp, lp;
2237       png_uint_32 sum = 0, lmins = mins;
2238       png_uint_32 i;
2239       int v;
2240
2241 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2242       /* We temporarily increase the "minimum sum" by the factor we
2243        * would reduce the sum of this filter, so that we can do the
2244        * early exit comparison without scaling the sum each time.
2245        */
2246       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2247       {
2248          int j;
2249          png_uint_32 lmhi, lmlo;
2250          lmlo = lmins & PNG_LOMASK;
2251          lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2252
2253          for (j = 0; j < num_p_filters; j++)
2254          {
2255             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
2256             {
2257                lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2258                   PNG_WEIGHT_SHIFT;
2259                lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2260                   PNG_WEIGHT_SHIFT;
2261             }
2262          }
2263
2264          lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2265             PNG_COST_SHIFT;
2266          lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2267             PNG_COST_SHIFT;
2268
2269          if (lmhi > PNG_HIMASK)
2270             lmins = PNG_MAXSUM;
2271          else
2272             lmins = (lmhi << PNG_HISHIFT) + lmlo;
2273       }
2274 #endif
2275
2276       for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
2277            i++, rp++, dp++)
2278       {
2279          v = *dp = *rp;
2280
2281          sum += (v < 128) ? v : 256 - v;
2282       }
2283       for (lp = row_buf + 1; i < row_bytes;
2284          i++, rp++, lp++, dp++)
2285       {
2286          v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
2287
2288          sum += (v < 128) ? v : 256 - v;
2289
2290          if (sum > lmins)  /* We are already worse, don't continue. */
2291             break;
2292       }
2293
2294 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2295       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2296       {
2297          int j;
2298          png_uint_32 sumhi, sumlo;
2299          sumlo = sum & PNG_LOMASK;
2300          sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2301
2302          for (j = 0; j < num_p_filters; j++)
2303          {
2304             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
2305             {
2306                sumlo = (sumlo * png_ptr->inv_filter_weights[j]) >>
2307                   PNG_WEIGHT_SHIFT;
2308                sumhi = (sumhi * png_ptr->inv_filter_weights[j]) >>
2309                   PNG_WEIGHT_SHIFT;
2310             }
2311          }
2312
2313          sumlo = (sumlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2314             PNG_COST_SHIFT;
2315          sumhi = (sumhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
2316             PNG_COST_SHIFT;
2317
2318          if (sumhi > PNG_HIMASK)
2319             sum = PNG_MAXSUM;
2320          else
2321             sum = (sumhi << PNG_HISHIFT) + sumlo;
2322       }
2323 #endif
2324
2325       if (sum < mins)
2326       {
2327          mins = sum;
2328          best_row = png_ptr->sub_row;
2329       }
2330    }
2331
2332    /* up filter */
2333    if (filter_to_do == PNG_FILTER_UP)
2334    {
2335       png_bytep rp, dp, pp;
2336       png_uint_32 i;
2337
2338       for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
2339            pp = prev_row + 1; i < row_bytes;
2340            i++, rp++, pp++, dp++)
2341       {
2342          *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
2343       }
2344       best_row = png_ptr->up_row;
2345    }
2346
2347    else if (filter_to_do & PNG_FILTER_UP)
2348    {
2349       png_bytep rp, dp, pp;
2350       png_uint_32 sum = 0, lmins = mins;
2351       png_uint_32 i;
2352       int v;
2353
2354
2355 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2356       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2357       {
2358          int j;
2359          png_uint_32 lmhi, lmlo;
2360          lmlo = lmins & PNG_LOMASK;
2361          lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2362
2363          for (j = 0; j < num_p_filters; j++)
2364          {
2365             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
2366             {
2367                lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2368                   PNG_WEIGHT_SHIFT;
2369                lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2370                   PNG_WEIGHT_SHIFT;
2371             }
2372          }
2373
2374          lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
2375             PNG_COST_SHIFT;
2376          lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
2377             PNG_COST_SHIFT;
2378
2379          if (lmhi > PNG_HIMASK)
2380             lmins = PNG_MAXSUM;
2381          else
2382             lmins = (lmhi << PNG_HISHIFT) + lmlo;
2383       }
2384 #endif
2385
2386       for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
2387            pp = prev_row + 1; i < row_bytes; i++)
2388       {
2389          v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2390
2391          sum += (v < 128) ? v : 256 - v;
2392
2393          if (sum > lmins)  /* We are already worse, don't continue. */
2394             break;
2395       }
2396
2397 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2398       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2399       {
2400          int j;
2401          png_uint_32 sumhi, sumlo;
2402          sumlo = sum & PNG_LOMASK;
2403          sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2404
2405          for (j = 0; j < num_p_filters; j++)
2406          {
2407             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
2408             {
2409                sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2410                   PNG_WEIGHT_SHIFT;
2411                sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2412                   PNG_WEIGHT_SHIFT;
2413             }
2414          }
2415
2416          sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
2417             PNG_COST_SHIFT;
2418          sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
2419             PNG_COST_SHIFT;
2420
2421          if (sumhi > PNG_HIMASK)
2422             sum = PNG_MAXSUM;
2423          else
2424             sum = (sumhi << PNG_HISHIFT) + sumlo;
2425       }
2426 #endif
2427
2428       if (sum < mins)
2429       {
2430          mins = sum;
2431          best_row = png_ptr->up_row;
2432       }
2433    }
2434
2435    /* avg filter */
2436    if (filter_to_do == PNG_FILTER_AVG)
2437    {
2438       png_bytep rp, dp, pp, lp;
2439       png_uint_32 i;
2440       for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
2441            pp = prev_row + 1; i < bpp; i++)
2442       {
2443          *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
2444       }
2445       for (lp = row_buf + 1; i < row_bytes; i++)
2446       {
2447          *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
2448                  & 0xff);
2449       }
2450       best_row = png_ptr->avg_row;
2451    }
2452
2453    else if (filter_to_do & PNG_FILTER_AVG)
2454    {
2455       png_bytep rp, dp, pp, lp;
2456       png_uint_32 sum = 0, lmins = mins;
2457       png_uint_32 i;
2458       int v;
2459
2460 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2461       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2462       {
2463          int j;
2464          png_uint_32 lmhi, lmlo;
2465          lmlo = lmins & PNG_LOMASK;
2466          lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2467
2468          for (j = 0; j < num_p_filters; j++)
2469          {
2470             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_AVG)
2471             {
2472                lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2473                   PNG_WEIGHT_SHIFT;
2474                lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2475                   PNG_WEIGHT_SHIFT;
2476             }
2477          }
2478
2479          lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
2480             PNG_COST_SHIFT;
2481          lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
2482             PNG_COST_SHIFT;
2483
2484          if (lmhi > PNG_HIMASK)
2485             lmins = PNG_MAXSUM;
2486          else
2487             lmins = (lmhi << PNG_HISHIFT) + lmlo;
2488       }
2489 #endif
2490
2491       for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
2492            pp = prev_row + 1; i < bpp; i++)
2493       {
2494          v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
2495
2496          sum += (v < 128) ? v : 256 - v;
2497       }
2498       for (lp = row_buf + 1; i < row_bytes; i++)
2499       {
2500          v = *dp++ =
2501           (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) & 0xff);
2502
2503          sum += (v < 128) ? v : 256 - v;
2504
2505          if (sum > lmins)  /* We are already worse, don't continue. */
2506             break;
2507       }
2508
2509 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2510       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2511       {
2512          int j;
2513          png_uint_32 sumhi, sumlo;
2514          sumlo = sum & PNG_LOMASK;
2515          sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2516
2517          for (j = 0; j < num_p_filters; j++)
2518          {
2519             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
2520             {
2521                sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2522                   PNG_WEIGHT_SHIFT;
2523                sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2524                   PNG_WEIGHT_SHIFT;
2525             }
2526          }
2527
2528          sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
2529             PNG_COST_SHIFT;
2530          sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
2531             PNG_COST_SHIFT;
2532
2533          if (sumhi > PNG_HIMASK)
2534             sum = PNG_MAXSUM;
2535          else
2536             sum = (sumhi << PNG_HISHIFT) + sumlo;
2537       }
2538 #endif
2539
2540       if (sum < mins)
2541       {
2542          mins = sum;
2543          best_row = png_ptr->avg_row;
2544       }
2545    }
2546
2547    /* Paeth filter */
2548    if (filter_to_do == PNG_FILTER_PAETH)
2549    {
2550       png_bytep rp, dp, pp, cp, lp;
2551       png_uint_32 i;
2552       for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
2553            pp = prev_row + 1; i < bpp; i++)
2554       {
2555          *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2556       }
2557
2558       for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
2559       {
2560          int a, b, c, pa, pb, pc, p;
2561
2562          b = *pp++;
2563          c = *cp++;
2564          a = *lp++;
2565
2566          p = b - c;
2567          pc = a - c;
2568
2569 #ifdef PNG_USE_ABS
2570          pa = abs(p);
2571          pb = abs(pc);
2572          pc = abs(p + pc);
2573 #else
2574          pa = p < 0 ? -p : p;
2575          pb = pc < 0 ? -pc : pc;
2576          pc = (p + pc) < 0 ? -(p + pc) : p + pc;
2577 #endif
2578
2579          p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
2580
2581          *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
2582       }
2583       best_row = png_ptr->paeth_row;
2584    }
2585
2586    else if (filter_to_do & PNG_FILTER_PAETH)
2587    {
2588       png_bytep rp, dp, pp, cp, lp;
2589       png_uint_32 sum = 0, lmins = mins;
2590       png_uint_32 i;
2591       int v;
2592
2593 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2594       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2595       {
2596          int j;
2597          png_uint_32 lmhi, lmlo;
2598          lmlo = lmins & PNG_LOMASK;
2599          lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
2600
2601          for (j = 0; j < num_p_filters; j++)
2602          {
2603             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
2604             {
2605                lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
2606                   PNG_WEIGHT_SHIFT;
2607                lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
2608                   PNG_WEIGHT_SHIFT;
2609             }
2610          }
2611
2612          lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2613             PNG_COST_SHIFT;
2614          lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2615             PNG_COST_SHIFT;
2616
2617          if (lmhi > PNG_HIMASK)
2618             lmins = PNG_MAXSUM;
2619          else
2620             lmins = (lmhi << PNG_HISHIFT) + lmlo;
2621       }
2622 #endif
2623
2624       for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
2625            pp = prev_row + 1; i < bpp; i++)
2626       {
2627          v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
2628
2629          sum += (v < 128) ? v : 256 - v;
2630       }
2631
2632       for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
2633       {
2634          int a, b, c, pa, pb, pc, p;
2635
2636          b = *pp++;
2637          c = *cp++;
2638          a = *lp++;
2639
2640 #ifndef PNG_SLOW_PAETH
2641          p = b - c;
2642          pc = a - c;
2643 #ifdef PNG_USE_ABS
2644          pa = abs(p);
2645          pb = abs(pc);
2646          pc = abs(p + pc);
2647 #else
2648          pa = p < 0 ? -p : p;
2649          pb = pc < 0 ? -pc : pc;
2650          pc = (p + pc) < 0 ? -(p + pc) : p + pc;
2651 #endif
2652          p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
2653 #else /* PNG_SLOW_PAETH */
2654          p = a + b - c;
2655          pa = abs(p - a);
2656          pb = abs(p - b);
2657          pc = abs(p - c);
2658          if (pa <= pb && pa <= pc)
2659             p = a;
2660          else if (pb <= pc)
2661             p = b;
2662          else
2663             p = c;
2664 #endif /* PNG_SLOW_PAETH */
2665
2666          v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
2667
2668          sum += (v < 128) ? v : 256 - v;
2669
2670          if (sum > lmins)  /* We are already worse, don't continue. */
2671             break;
2672       }
2673
2674 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2675       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
2676       {
2677          int j;
2678          png_uint_32 sumhi, sumlo;
2679          sumlo = sum & PNG_LOMASK;
2680          sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
2681
2682          for (j = 0; j < num_p_filters; j++)
2683          {
2684             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
2685             {
2686                sumlo = (sumlo * png_ptr->filter_weights[j]) >>
2687                   PNG_WEIGHT_SHIFT;
2688                sumhi = (sumhi * png_ptr->filter_weights[j]) >>
2689                   PNG_WEIGHT_SHIFT;
2690             }
2691          }
2692
2693          sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2694             PNG_COST_SHIFT;
2695          sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
2696             PNG_COST_SHIFT;
2697
2698          if (sumhi > PNG_HIMASK)
2699             sum = PNG_MAXSUM;
2700          else
2701             sum = (sumhi << PNG_HISHIFT) + sumlo;
2702       }
2703 #endif
2704
2705       if (sum < mins)
2706       {
2707          best_row = png_ptr->paeth_row;
2708       }
2709    }
2710 #endif /* PNG_NO_WRITE_FILTER */
2711    /* Do the actual writing of the filtered row data from the chosen filter. */
2712
2713    png_write_filtered_row(png_ptr, best_row);
2714
2715 #ifndef PNG_NO_WRITE_FILTER
2716 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
2717    /* Save the type of filter we picked this time for future calculations */
2718    if (png_ptr->num_prev_filters > 0)
2719    {
2720       int j;
2721       for (j = 1; j < num_p_filters; j++)
2722       {
2723          png_ptr->prev_filters[j] = png_ptr->prev_filters[j - 1];
2724       }
2725       png_ptr->prev_filters[j] = best_row[0];
2726    }
2727 #endif
2728 #endif /* PNG_NO_WRITE_FILTER */
2729 }
2730
2731
2732 /* Do the actual writing of a previously filtered row. */
2733 void /* PRIVATE */
2734 png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row)
2735 {
2736    png_debug(1, "in png_write_filtered_row\n");
2737    png_debug1(2, "filter = %d\n", filtered_row[0]);
2738    /* set up the zlib input buffer */
2739
2740    png_ptr->zstream.next_in = filtered_row;
2741    png_ptr->zstream.avail_in = (uInt)png_ptr->row_info.rowbytes + 1;
2742    /* repeat until we have compressed all the data */
2743    do
2744    {
2745       int ret; /* return of zlib */
2746
2747       /* compress the data */
2748       ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
2749       /* check for compression errors */
2750       if (ret != Z_OK)
2751       {
2752          if (png_ptr->zstream.msg != NULL)
2753             png_error(png_ptr, png_ptr->zstream.msg);
2754          else
2755             png_error(png_ptr, "zlib error");
2756       }
2757
2758       /* see if it is time to write another IDAT */
2759       if (!(png_ptr->zstream.avail_out))
2760       {
2761          /* write the IDAT and reset the zlib output buffer */
2762          png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
2763          png_ptr->zstream.next_out = png_ptr->zbuf;
2764          png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
2765       }
2766    /* repeat until all data has been compressed */
2767    } while (png_ptr->zstream.avail_in);
2768
2769    /* swap the current and previous rows */
2770    if (png_ptr->prev_row != NULL)
2771    {
2772       png_bytep tptr;
2773
2774       tptr = png_ptr->prev_row;
2775       png_ptr->prev_row = png_ptr->row_buf;
2776       png_ptr->row_buf = tptr;
2777    }
2778
2779    /* finish row - updates counters and flushes zlib if last row */
2780    png_write_finish_row(png_ptr);
2781
2782 #if defined(PNG_WRITE_FLUSH_SUPPORTED)
2783    png_ptr->flush_rows++;
2784
2785    if (png_ptr->flush_dist > 0 &&
2786        png_ptr->flush_rows >= png_ptr->flush_dist)
2787    {
2788       png_write_flush(png_ptr);
2789    }
2790 #endif
2791 }
2792 #endif /* PNG_WRITE_SUPPORTED */