reactos/dll/3rdparty/libpng/pngread.c

   1
   2 /* pngread.c - read a PNG file
   3  *
   4  * Last changed in libpng 1.5.7 [December 15, 2011]
   5  * Copyright (c) 1998-2011 Glenn Randers-Pehrson
   6  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
   7  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
   8  *
   9  * This code is released under the libpng license.
  10  * For conditions of distribution and use, see the disclaimer
  11  * and license in png.h
  12  *
  13  * This file contains routines that an application calls directly to
  14  * read a PNG file or stream.
  15  */
  16
  17 #include "pngpriv.h"
  18
  19 #ifdef PNG_READ_SUPPORTED
  20
  21 /* Create a PNG structure for reading, and allocate any memory needed. */
  22 PNG_FUNCTION(png_structp,PNGAPI
  23 png_create_read_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
  24     png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED)
  25 {
  26
  27 #ifdef PNG_USER_MEM_SUPPORTED
  28    return (png_create_read_struct_2(user_png_ver, error_ptr, error_fn,
  29        warn_fn, NULL, NULL, NULL));
  30 }
  31
  32 /* Alternate create PNG structure for reading, and allocate any memory
  33  * needed.
  34  */
  35 PNG_FUNCTION(png_structp,PNGAPI
  36 png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
  37     png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
  38     png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
  39 {
  40 #endif /* PNG_USER_MEM_SUPPORTED */
  41
  42 #ifdef PNG_SETJMP_SUPPORTED
  43    volatile
  44 #endif
  45    png_structp png_ptr;
  46    volatile int png_cleanup_needed = 0;
  47
  48 #ifdef PNG_SETJMP_SUPPORTED
  49 #ifdef USE_FAR_KEYWORD
  50    jmp_buf tmp_jmpbuf;
  51 #endif
  52 #endif
  53
  54    png_debug(1, "in png_create_read_struct");
  55
  56 #ifdef PNG_USER_MEM_SUPPORTED
  57    png_ptr = (png_structp)png_create_struct_2(PNG_STRUCT_PNG,
  58        malloc_fn, mem_ptr);
  59 #else
  60    png_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG);
  61 #endif
  62    if (png_ptr == NULL)
  63       return (NULL);
  64
  65    /* Added at libpng-1.2.6 */
  66 #ifdef PNG_USER_LIMITS_SUPPORTED
  67    png_ptr->user_width_max = PNG_USER_WIDTH_MAX;
  68    png_ptr->user_height_max = PNG_USER_HEIGHT_MAX;
  69
  70 #  ifdef PNG_USER_CHUNK_CACHE_MAX
  71    /* Added at libpng-1.2.43 and 1.4.0 */
  72    png_ptr->user_chunk_cache_max = PNG_USER_CHUNK_CACHE_MAX;
  73 #  endif
  74
  75 #  ifdef PNG_SET_USER_CHUNK_MALLOC_MAX
  76    /* Added at libpng-1.2.43 and 1.4.1 */
  77    png_ptr->user_chunk_malloc_max = PNG_USER_CHUNK_MALLOC_MAX;
  78 #  endif
  79 #endif
  80
  81 #ifdef PNG_SETJMP_SUPPORTED
  82 /* Applications that neglect to set up their own setjmp() and then
  83  * encounter a png_error() will longjmp here.  Since the jmpbuf is
  84  * then meaningless we abort instead of returning.
  85  */
  86 #ifdef USE_FAR_KEYWORD
  87    if (setjmp(tmp_jmpbuf))
  88 #else
  89    if (setjmp(png_jmpbuf(png_ptr))) /* Sets longjmp to match setjmp */
  90 #endif
  91       PNG_ABORT();
  92 #ifdef USE_FAR_KEYWORD
  93    png_memcpy(png_jmpbuf(png_ptr), tmp_jmpbuf, png_sizeof(jmp_buf));
  94 #endif
  95 #endif /* PNG_SETJMP_SUPPORTED */
  96
  97 #ifdef PNG_USER_MEM_SUPPORTED
  98    png_set_mem_fn(png_ptr, mem_ptr, malloc_fn, free_fn);
  99 #endif
 100
 101    png_set_error_fn(png_ptr, error_ptr, error_fn, warn_fn);
 102
 103    /* Call the general version checker (shared with read and write code): */
 104    if (!png_user_version_check(png_ptr, user_png_ver))
 105       png_cleanup_needed = 1;
 106
 107    if (!png_cleanup_needed)
 108    {
 109    /* Initialize zbuf - compression buffer */
 110    png_ptr->zbuf_size = PNG_ZBUF_SIZE;
 111    png_ptr->zbuf = (png_bytep)png_malloc_warn(png_ptr, png_ptr->zbuf_size);
 112
 113    if (png_ptr->zbuf == NULL)
 114       png_cleanup_needed = 1;
 115    }
 116
 117    png_ptr->zstream.zalloc = png_zalloc;
 118    png_ptr->zstream.zfree = png_zfree;
 119    png_ptr->zstream.opaque = (voidpf)png_ptr;
 120
 121    if (!png_cleanup_needed)
 122    {
 123       switch (inflateInit(&png_ptr->zstream))
 124       {
 125          case Z_OK:
 126             break; /* Do nothing */
 127
 128          case Z_MEM_ERROR:
 129             png_warning(png_ptr, "zlib memory error");
 130             png_cleanup_needed = 1;
 131             break;
 132
 133          case Z_STREAM_ERROR:
 134             png_warning(png_ptr, "zlib stream error");
 135             png_cleanup_needed = 1;
 136             break;
 137
 138          case Z_VERSION_ERROR:
 139             png_warning(png_ptr, "zlib version error");
 140             png_cleanup_needed = 1;
 141             break;
 142
 143          default: png_warning(png_ptr, "Unknown zlib error");
 144             png_cleanup_needed = 1;
 145       }
 146    }
 147
 148    if (png_cleanup_needed)
 149    {
 150       /* Clean up PNG structure and deallocate any memory. */
 151       png_free(png_ptr, png_ptr->zbuf);
 152       png_ptr->zbuf = NULL;
 153 #ifdef PNG_USER_MEM_SUPPORTED
 154       png_destroy_struct_2((png_voidp)png_ptr,
 155           (png_free_ptr)free_fn, (png_voidp)mem_ptr);
 156 #else
 157       png_destroy_struct((png_voidp)png_ptr);
 158 #endif
 159       return (NULL);
 160    }
 161
 162    png_ptr->zstream.next_out = png_ptr->zbuf;
 163    png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
 164
 165    png_set_read_fn(png_ptr, NULL, NULL);
 166
 167
 168    return (png_ptr);
 169 }
 170
 171
 172 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 173 /* Read the information before the actual image data.  This has been
 174  * changed in v0.90 to allow reading a file that already has the magic
 175  * bytes read from the stream.  You can tell libpng how many bytes have
 176  * been read from the beginning of the stream (up to the maximum of 8)
 177  * via png_set_sig_bytes(), and we will only check the remaining bytes
 178  * here.  The application can then have access to the signature bytes we
 179  * read if it is determined that this isn't a valid PNG file.
 180  */
 181 void PNGAPI
 182 png_read_info(png_structp png_ptr, png_infop info_ptr)
 183 {
 184    png_debug(1, "in png_read_info");
 185
 186    if (png_ptr == NULL || info_ptr == NULL)
 187       return;
 188
 189    /* Read and check the PNG file signature. */
 190    png_read_sig(png_ptr, info_ptr);
 191
 192    for (;;)
 193    {
 194       png_uint_32 length = png_read_chunk_header(png_ptr);
 195       png_uint_32 chunk_name = png_ptr->chunk_name;
 196
 197       /* This should be a binary subdivision search or a hash for
 198        * matching the chunk name rather than a linear search.
 199        */
 200       if (chunk_name == png_IDAT)
 201          if (png_ptr->mode & PNG_AFTER_IDAT)
 202             png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
 203
 204       if (chunk_name == png_IHDR)
 205          png_handle_IHDR(png_ptr, info_ptr, length);
 206
 207       else if (chunk_name == png_IEND)
 208          png_handle_IEND(png_ptr, info_ptr, length);
 209
 210 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
 211       else if (png_chunk_unknown_handling(png_ptr, chunk_name) !=
 212          PNG_HANDLE_CHUNK_AS_DEFAULT)
 213       {
 214          if (chunk_name == png_IDAT)
 215             png_ptr->mode |= PNG_HAVE_IDAT;
 216
 217          png_handle_unknown(png_ptr, info_ptr, length);
 218
 219          if (chunk_name == png_PLTE)
 220             png_ptr->mode |= PNG_HAVE_PLTE;
 221
 222          else if (chunk_name == png_IDAT)
 223          {
 224             if (!(png_ptr->mode & PNG_HAVE_IHDR))
 225                png_error(png_ptr, "Missing IHDR before IDAT");
 226
 227             else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
 228                 !(png_ptr->mode & PNG_HAVE_PLTE))
 229                png_error(png_ptr, "Missing PLTE before IDAT");
 230
 231             break;
 232          }
 233       }
 234 #endif
 235       else if (chunk_name == png_PLTE)
 236          png_handle_PLTE(png_ptr, info_ptr, length);
 237
 238       else if (chunk_name == png_IDAT)
 239       {
 240          if (!(png_ptr->mode & PNG_HAVE_IHDR))
 241             png_error(png_ptr, "Missing IHDR before IDAT");
 242
 243          else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
 244              !(png_ptr->mode & PNG_HAVE_PLTE))
 245             png_error(png_ptr, "Missing PLTE before IDAT");
 246
 247          png_ptr->idat_size = length;
 248          png_ptr->mode |= PNG_HAVE_IDAT;
 249          break;
 250       }
 251
 252 #ifdef PNG_READ_bKGD_SUPPORTED
 253       else if (chunk_name == png_bKGD)
 254          png_handle_bKGD(png_ptr, info_ptr, length);
 255 #endif
 256
 257 #ifdef PNG_READ_cHRM_SUPPORTED
 258       else if (chunk_name == png_cHRM)
 259          png_handle_cHRM(png_ptr, info_ptr, length);
 260 #endif
 261
 262 #ifdef PNG_READ_gAMA_SUPPORTED
 263       else if (chunk_name == png_gAMA)
 264          png_handle_gAMA(png_ptr, info_ptr, length);
 265 #endif
 266
 267 #ifdef PNG_READ_hIST_SUPPORTED
 268       else if (chunk_name == png_hIST)
 269          png_handle_hIST(png_ptr, info_ptr, length);
 270 #endif
 271
 272 #ifdef PNG_READ_oFFs_SUPPORTED
 273       else if (chunk_name == png_oFFs)
 274          png_handle_oFFs(png_ptr, info_ptr, length);
 275 #endif
 276
 277 #ifdef PNG_READ_pCAL_SUPPORTED
 278       else if (chunk_name == png_pCAL)
 279          png_handle_pCAL(png_ptr, info_ptr, length);
 280 #endif
 281
 282 #ifdef PNG_READ_sCAL_SUPPORTED
 283       else if (chunk_name == png_sCAL)
 284          png_handle_sCAL(png_ptr, info_ptr, length);
 285 #endif
 286
 287 #ifdef PNG_READ_pHYs_SUPPORTED
 288       else if (chunk_name == png_pHYs)
 289          png_handle_pHYs(png_ptr, info_ptr, length);
 290 #endif
 291
 292 #ifdef PNG_READ_sBIT_SUPPORTED
 293       else if (chunk_name == png_sBIT)
 294          png_handle_sBIT(png_ptr, info_ptr, length);
 295 #endif
 296
 297 #ifdef PNG_READ_sRGB_SUPPORTED
 298       else if (chunk_name == png_sRGB)
 299          png_handle_sRGB(png_ptr, info_ptr, length);
 300 #endif
 301
 302 #ifdef PNG_READ_iCCP_SUPPORTED
 303       else if (chunk_name == png_iCCP)
 304          png_handle_iCCP(png_ptr, info_ptr, length);
 305 #endif
 306
 307 #ifdef PNG_READ_sPLT_SUPPORTED
 308       else if (chunk_name == png_sPLT)
 309          png_handle_sPLT(png_ptr, info_ptr, length);
 310 #endif
 311
 312 #ifdef PNG_READ_tEXt_SUPPORTED
 313       else if (chunk_name == png_tEXt)
 314          png_handle_tEXt(png_ptr, info_ptr, length);
 315 #endif
 316
 317 #ifdef PNG_READ_tIME_SUPPORTED
 318       else if (chunk_name == png_tIME)
 319          png_handle_tIME(png_ptr, info_ptr, length);
 320 #endif
 321
 322 #ifdef PNG_READ_tRNS_SUPPORTED
 323       else if (chunk_name == png_tRNS)
 324          png_handle_tRNS(png_ptr, info_ptr, length);
 325 #endif
 326
 327 #ifdef PNG_READ_zTXt_SUPPORTED
 328       else if (chunk_name == png_zTXt)
 329          png_handle_zTXt(png_ptr, info_ptr, length);
 330 #endif
 331
 332 #ifdef PNG_READ_iTXt_SUPPORTED
 333       else if (chunk_name == png_iTXt)
 334          png_handle_iTXt(png_ptr, info_ptr, length);
 335 #endif
 336
 337       else
 338          png_handle_unknown(png_ptr, info_ptr, length);
 339    }
 340 }
 341 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
 342
 343 /* Optional call to update the users info_ptr structure */
 344 void PNGAPI
 345 png_read_update_info(png_structp png_ptr, png_infop info_ptr)
 346 {
 347    png_debug(1, "in png_read_update_info");
 348
 349    if (png_ptr == NULL)
 350       return;
 351
 352    png_read_start_row(png_ptr);
 353
 354 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
 355    png_read_transform_info(png_ptr, info_ptr);
 356 #else
 357    PNG_UNUSED(info_ptr)
 358 #endif
 359 }
 360
 361 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 362 /* Initialize palette, background, etc, after transformations
 363  * are set, but before any reading takes place.  This allows
 364  * the user to obtain a gamma-corrected palette, for example.
 365  * If the user doesn't call this, we will do it ourselves.
 366  */
 367 void PNGAPI
 368 png_start_read_image(png_structp png_ptr)
 369 {
 370    png_debug(1, "in png_start_read_image");
 371
 372    if (png_ptr != NULL)
 373      png_read_start_row(png_ptr);
 374 }
 375 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
 376
 377 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 378 void PNGAPI
 379 png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
 380 {
 381    int ret;
 382
 383    png_row_info row_info;
 384
 385    if (png_ptr == NULL)
 386       return;
 387
 388    png_debug2(1, "in png_read_row (row %lu, pass %d)",
 389        (unsigned long)png_ptr->row_number, png_ptr->pass);
 390
 391    /* png_read_start_row sets the information (in particular iwidth) for this
 392     * interlace pass.
 393     */
 394    if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
 395       png_read_start_row(png_ptr);
 396
 397    /* 1.5.6: row_info moved out of png_struct to a local here. */
 398    row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
 399    row_info.color_type = png_ptr->color_type;
 400    row_info.bit_depth = png_ptr->bit_depth;
 401    row_info.channels = png_ptr->channels;
 402    row_info.pixel_depth = png_ptr->pixel_depth;
 403    row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
 404
 405    if (png_ptr->row_number == 0 && png_ptr->pass == 0)
 406    {
 407    /* Check for transforms that have been set but were defined out */
 408 #if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED)
 409    if (png_ptr->transformations & PNG_INVERT_MONO)
 410       png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined");
 411 #endif
 412
 413 #if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED)
 414    if (png_ptr->transformations & PNG_FILLER)
 415       png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined");
 416 #endif
 417
 418 #if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
 419     !defined(PNG_READ_PACKSWAP_SUPPORTED)
 420    if (png_ptr->transformations & PNG_PACKSWAP)
 421       png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined");
 422 #endif
 423
 424 #if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED)
 425    if (png_ptr->transformations & PNG_PACK)
 426       png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined");
 427 #endif
 428
 429 #if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED)
 430    if (png_ptr->transformations & PNG_SHIFT)
 431       png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined");
 432 #endif
 433
 434 #if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED)
 435    if (png_ptr->transformations & PNG_BGR)
 436       png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined");
 437 #endif
 438
 439 #if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED)
 440    if (png_ptr->transformations & PNG_SWAP_BYTES)
 441       png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined");
 442 #endif
 443    }
 444
 445 #ifdef PNG_READ_INTERLACING_SUPPORTED
 446    /* If interlaced and we do not need a new row, combine row and return.
 447     * Notice that the pixels we have from previous rows have been transformed
 448     * already; we can only combine like with like (transformed or
 449     * untransformed) and, because of the libpng API for interlaced images, this
 450     * means we must transform before de-interlacing.
 451     */
 452    if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
 453    {
 454       switch (png_ptr->pass)
 455       {
 456          case 0:
 457             if (png_ptr->row_number & 0x07)
 458             {
 459                if (dsp_row != NULL)
 460                   png_combine_row(png_ptr, dsp_row, 1/*display*/);
 461                png_read_finish_row(png_ptr);
 462                return;
 463             }
 464             break;
 465
 466          case 1:
 467             if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
 468             {
 469                if (dsp_row != NULL)
 470                   png_combine_row(png_ptr, dsp_row, 1/*display*/);
 471
 472                png_read_finish_row(png_ptr);
 473                return;
 474             }
 475             break;
 476
 477          case 2:
 478             if ((png_ptr->row_number & 0x07) != 4)
 479             {
 480                if (dsp_row != NULL && (png_ptr->row_number & 4))
 481                   png_combine_row(png_ptr, dsp_row, 1/*display*/);
 482
 483                png_read_finish_row(png_ptr);
 484                return;
 485             }
 486             break;
 487
 488          case 3:
 489             if ((png_ptr->row_number & 3) || png_ptr->width < 3)
 490             {
 491                if (dsp_row != NULL)
 492                   png_combine_row(png_ptr, dsp_row, 1/*display*/);
 493
 494                png_read_finish_row(png_ptr);
 495                return;
 496             }
 497             break;
 498
 499          case 4:
 500             if ((png_ptr->row_number & 3) != 2)
 501             {
 502                if (dsp_row != NULL && (png_ptr->row_number & 2))
 503                   png_combine_row(png_ptr, dsp_row, 1/*display*/);
 504
 505                png_read_finish_row(png_ptr);
 506                return;
 507             }
 508             break;
 509          case 5:
 510             if ((png_ptr->row_number & 1) || png_ptr->width < 2)
 511             {
 512                if (dsp_row != NULL)
 513                   png_combine_row(png_ptr, dsp_row, 1/*display*/);
 514
 515                png_read_finish_row(png_ptr);
 516                return;
 517             }
 518             break;
 519
 520          default:
 521          case 6:
 522             if (!(png_ptr->row_number & 1))
 523             {
 524                png_read_finish_row(png_ptr);
 525                return;
 526             }
 527             break;
 528       }
 529    }
 530 #endif
 531
 532    if (!(png_ptr->mode & PNG_HAVE_IDAT))
 533       png_error(png_ptr, "Invalid attempt to read row data");
 534
 535    png_ptr->zstream.next_out = png_ptr->row_buf;
 536    png_ptr->zstream.avail_out =
 537        (uInt)(PNG_ROWBYTES(png_ptr->pixel_depth,
 538        png_ptr->iwidth) + 1);
 539
 540    do
 541    {
 542       if (!(png_ptr->zstream.avail_in))
 543       {
 544          while (!png_ptr->idat_size)
 545          {
 546             png_crc_finish(png_ptr, 0);
 547
 548             png_ptr->idat_size = png_read_chunk_header(png_ptr);
 549             if (png_ptr->chunk_name != png_IDAT)
 550                png_error(png_ptr, "Not enough image data");
 551          }
 552          png_ptr->zstream.avail_in = (uInt)png_ptr->zbuf_size;
 553          png_ptr->zstream.next_in = png_ptr->zbuf;
 554          if (png_ptr->zbuf_size > png_ptr->idat_size)
 555             png_ptr->zstream.avail_in = (uInt)png_ptr->idat_size;
 556          png_crc_read(png_ptr, png_ptr->zbuf,
 557              (png_size_t)png_ptr->zstream.avail_in);
 558          png_ptr->idat_size -= png_ptr->zstream.avail_in;
 559       }
 560
 561       ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
 562
 563       if (ret == Z_STREAM_END)
 564       {
 565          if (png_ptr->zstream.avail_out || png_ptr->zstream.avail_in ||
 566             png_ptr->idat_size)
 567             png_benign_error(png_ptr, "Extra compressed data");
 568          png_ptr->mode |= PNG_AFTER_IDAT;
 569          png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
 570          break;
 571       }
 572
 573       if (ret != Z_OK)
 574          png_error(png_ptr, png_ptr->zstream.msg ? png_ptr->zstream.msg :
 575              "Decompression error");
 576
 577    } while (png_ptr->zstream.avail_out);
 578
 579    if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
 580    {
 581       if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
 582          png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
 583             png_ptr->prev_row + 1, png_ptr->row_buf[0]);
 584       else
 585          png_error(png_ptr, "bad adaptive filter value");
 586    }
 587
 588    /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
 589     * 1.5.6, while the buffer really is this big in current versions of libpng
 590     * it may not be in the future, so this was changed just to copy the
 591     * interlaced count:
 592     */
 593    png_memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
 594
 595 #ifdef PNG_MNG_FEATURES_SUPPORTED
 596    if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
 597        (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
 598    {
 599       /* Intrapixel differencing */
 600       png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1);
 601    }
 602 #endif
 603
 604
 605 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
 606    if (png_ptr->transformations)
 607       png_do_read_transformations(png_ptr, &row_info);
 608 #endif
 609
 610    /* The transformed pixel depth should match the depth now in row_info. */
 611    if (png_ptr->transformed_pixel_depth == 0)
 612    {
 613       png_ptr->transformed_pixel_depth = row_info.pixel_depth;
 614       if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
 615          png_error(png_ptr, "sequential row overflow");
 616    }
 617
 618    else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
 619       png_error(png_ptr, "internal sequential row size calculation error");
 620
 621 #ifdef PNG_READ_INTERLACING_SUPPORTED
 622    /* Blow up interlaced rows to full size */
 623    if (png_ptr->interlaced &&
 624       (png_ptr->transformations & PNG_INTERLACE))
 625    {
 626       if (png_ptr->pass < 6)
 627          png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
 628             png_ptr->transformations);
 629
 630       if (dsp_row != NULL)
 631          png_combine_row(png_ptr, dsp_row, 1/*display*/);
 632
 633       if (row != NULL)
 634          png_combine_row(png_ptr, row, 0/*row*/);
 635    }
 636
 637    else
 638 #endif
 639    {
 640       if (row != NULL)
 641          png_combine_row(png_ptr, row, -1/*ignored*/);
 642
 643       if (dsp_row != NULL)
 644          png_combine_row(png_ptr, dsp_row, -1/*ignored*/);
 645    }
 646    png_read_finish_row(png_ptr);
 647
 648    if (png_ptr->read_row_fn != NULL)
 649       (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
 650 }
 651 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
 652
 653 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 654 /* Read one or more rows of image data.  If the image is interlaced,
 655  * and png_set_interlace_handling() has been called, the rows need to
 656  * contain the contents of the rows from the previous pass.  If the
 657  * image has alpha or transparency, and png_handle_alpha()[*] has been
 658  * called, the rows contents must be initialized to the contents of the
 659  * screen.
 660  *
 661  * "row" holds the actual image, and pixels are placed in it
 662  * as they arrive.  If the image is displayed after each pass, it will
 663  * appear to "sparkle" in.  "display_row" can be used to display a
 664  * "chunky" progressive image, with finer detail added as it becomes
 665  * available.  If you do not want this "chunky" display, you may pass
 666  * NULL for display_row.  If you do not want the sparkle display, and
 667  * you have not called png_handle_alpha(), you may pass NULL for rows.
 668  * If you have called png_handle_alpha(), and the image has either an
 669  * alpha channel or a transparency chunk, you must provide a buffer for
 670  * rows.  In this case, you do not have to provide a display_row buffer
 671  * also, but you may.  If the image is not interlaced, or if you have
 672  * not called png_set_interlace_handling(), the display_row buffer will
 673  * be ignored, so pass NULL to it.
 674  *
 675  * [*] png_handle_alpha() does not exist yet, as of this version of libpng
 676  */
 677
 678 void PNGAPI
 679 png_read_rows(png_structp png_ptr, png_bytepp row,
 680     png_bytepp display_row, png_uint_32 num_rows)
 681 {
 682    png_uint_32 i;
 683    png_bytepp rp;
 684    png_bytepp dp;
 685
 686    png_debug(1, "in png_read_rows");
 687
 688    if (png_ptr == NULL)
 689       return;
 690
 691    rp = row;
 692    dp = display_row;
 693    if (rp != NULL && dp != NULL)
 694       for (i = 0; i < num_rows; i++)
 695       {
 696          png_bytep rptr = *rp++;
 697          png_bytep dptr = *dp++;
 698
 699          png_read_row(png_ptr, rptr, dptr);
 700       }
 701
 702    else if (rp != NULL)
 703       for (i = 0; i < num_rows; i++)
 704       {
 705          png_bytep rptr = *rp;
 706          png_read_row(png_ptr, rptr, NULL);
 707          rp++;
 708       }
 709
 710    else if (dp != NULL)
 711       for (i = 0; i < num_rows; i++)
 712       {
 713          png_bytep dptr = *dp;
 714          png_read_row(png_ptr, NULL, dptr);
 715          dp++;
 716       }
 717 }
 718 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
 719
 720 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 721 /* Read the entire image.  If the image has an alpha channel or a tRNS
 722  * chunk, and you have called png_handle_alpha()[*], you will need to
 723  * initialize the image to the current image that PNG will be overlaying.
 724  * We set the num_rows again here, in case it was incorrectly set in
 725  * png_read_start_row() by a call to png_read_update_info() or
 726  * png_start_read_image() if png_set_interlace_handling() wasn't called
 727  * prior to either of these functions like it should have been.  You can
 728  * only call this function once.  If you desire to have an image for
 729  * each pass of a interlaced image, use png_read_rows() instead.
 730  *
 731  * [*] png_handle_alpha() does not exist yet, as of this version of libpng
 732  */
 733 void PNGAPI
 734 png_read_image(png_structp png_ptr, png_bytepp image)
 735 {
 736    png_uint_32 i, image_height;
 737    int pass, j;
 738    png_bytepp rp;
 739
 740    png_debug(1, "in png_read_image");
 741
 742    if (png_ptr == NULL)
 743       return;
 744
 745 #ifdef PNG_READ_INTERLACING_SUPPORTED
 746    if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
 747    {
 748       pass = png_set_interlace_handling(png_ptr);
 749       /* And make sure transforms are initialized. */
 750       png_start_read_image(png_ptr);
 751    }
 752    else
 753    {
 754       if (png_ptr->interlaced && !(png_ptr->transformations & PNG_INTERLACE))
 755       {
 756          /* Caller called png_start_read_image or png_read_update_info without
 757           * first turning on the PNG_INTERLACE transform.  We can fix this here,
 758           * but the caller should do it!
 759           */
 760          png_warning(png_ptr, "Interlace handling should be turned on when "
 761             "using png_read_image");
 762          /* Make sure this is set correctly */
 763          png_ptr->num_rows = png_ptr->height;
 764       }
 765
 766       /* Obtain the pass number, which also turns on the PNG_INTERLACE flag in
 767        * the above error case.
 768        */
 769       pass = png_set_interlace_handling(png_ptr);
 770    }
 771 #else
 772    if (png_ptr->interlaced)
 773       png_error(png_ptr,
 774           "Cannot read interlaced image -- interlace handler disabled");
 775
 776    pass = 1;
 777 #endif
 778
 779    image_height=png_ptr->height;
 780
 781    for (j = 0; j < pass; j++)
 782    {
 783       rp = image;
 784       for (i = 0; i < image_height; i++)
 785       {
 786          png_read_row(png_ptr, *rp, NULL);
 787          rp++;
 788       }
 789    }
 790 }
 791 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
 792
 793 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 794 /* Read the end of the PNG file.  Will not read past the end of the
 795  * file, will verify the end is accurate, and will read any comments
 796  * or time information at the end of the file, if info is not NULL.
 797  */
 798 void PNGAPI
 799 png_read_end(png_structp png_ptr, png_infop info_ptr)
 800 {
 801    png_debug(1, "in png_read_end");
 802
 803    if (png_ptr == NULL)
 804       return;
 805
 806    png_crc_finish(png_ptr, 0); /* Finish off CRC from last IDAT chunk */
 807
 808    do
 809    {
 810       png_uint_32 length = png_read_chunk_header(png_ptr);
 811       png_uint_32 chunk_name = png_ptr->chunk_name;
 812
 813       if (chunk_name == png_IHDR)
 814          png_handle_IHDR(png_ptr, info_ptr, length);
 815
 816       else if (chunk_name == png_IEND)
 817          png_handle_IEND(png_ptr, info_ptr, length);
 818
 819 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
 820       else if (png_chunk_unknown_handling(png_ptr, chunk_name) !=
 821          PNG_HANDLE_CHUNK_AS_DEFAULT)
 822       {
 823          if (chunk_name == png_IDAT)
 824          {
 825             if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
 826                png_benign_error(png_ptr, "Too many IDATs found");
 827          }
 828          png_handle_unknown(png_ptr, info_ptr, length);
 829          if (chunk_name == png_PLTE)
 830             png_ptr->mode |= PNG_HAVE_PLTE;
 831       }
 832 #endif
 833
 834       else if (chunk_name == png_IDAT)
 835       {
 836          /* Zero length IDATs are legal after the last IDAT has been
 837           * read, but not after other chunks have been read.
 838           */
 839          if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
 840             png_benign_error(png_ptr, "Too many IDATs found");
 841
 842          png_crc_finish(png_ptr, length);
 843       }
 844       else if (chunk_name == png_PLTE)
 845          png_handle_PLTE(png_ptr, info_ptr, length);
 846
 847 #ifdef PNG_READ_bKGD_SUPPORTED
 848       else if (chunk_name == png_bKGD)
 849          png_handle_bKGD(png_ptr, info_ptr, length);
 850 #endif
 851
 852 #ifdef PNG_READ_cHRM_SUPPORTED
 853       else if (chunk_name == png_cHRM)
 854          png_handle_cHRM(png_ptr, info_ptr, length);
 855 #endif
 856
 857 #ifdef PNG_READ_gAMA_SUPPORTED
 858       else if (chunk_name == png_gAMA)
 859          png_handle_gAMA(png_ptr, info_ptr, length);
 860 #endif
 861
 862 #ifdef PNG_READ_hIST_SUPPORTED
 863       else if (chunk_name == png_hIST)
 864          png_handle_hIST(png_ptr, info_ptr, length);
 865 #endif
 866
 867 #ifdef PNG_READ_oFFs_SUPPORTED
 868       else if (chunk_name == png_oFFs)
 869          png_handle_oFFs(png_ptr, info_ptr, length);
 870 #endif
 871
 872 #ifdef PNG_READ_pCAL_SUPPORTED
 873       else if (chunk_name == png_pCAL)
 874          png_handle_pCAL(png_ptr, info_ptr, length);
 875 #endif
 876
 877 #ifdef PNG_READ_sCAL_SUPPORTED
 878       else if (chunk_name == png_sCAL)
 879          png_handle_sCAL(png_ptr, info_ptr, length);
 880 #endif
 881
 882 #ifdef PNG_READ_pHYs_SUPPORTED
 883       else if (chunk_name == png_pHYs)
 884          png_handle_pHYs(png_ptr, info_ptr, length);
 885 #endif
 886
 887 #ifdef PNG_READ_sBIT_SUPPORTED
 888       else if (chunk_name == png_sBIT)
 889          png_handle_sBIT(png_ptr, info_ptr, length);
 890 #endif
 891
 892 #ifdef PNG_READ_sRGB_SUPPORTED
 893       else if (chunk_name == png_sRGB)
 894          png_handle_sRGB(png_ptr, info_ptr, length);
 895 #endif
 896
 897 #ifdef PNG_READ_iCCP_SUPPORTED
 898       else if (chunk_name == png_iCCP)
 899          png_handle_iCCP(png_ptr, info_ptr, length);
 900 #endif
 901
 902 #ifdef PNG_READ_sPLT_SUPPORTED
 903       else if (chunk_name == png_sPLT)
 904          png_handle_sPLT(png_ptr, info_ptr, length);
 905 #endif
 906
 907 #ifdef PNG_READ_tEXt_SUPPORTED
 908       else if (chunk_name == png_tEXt)
 909          png_handle_tEXt(png_ptr, info_ptr, length);
 910 #endif
 911
 912 #ifdef PNG_READ_tIME_SUPPORTED
 913       else if (chunk_name == png_tIME)
 914          png_handle_tIME(png_ptr, info_ptr, length);
 915 #endif
 916
 917 #ifdef PNG_READ_tRNS_SUPPORTED
 918       else if (chunk_name == png_tRNS)
 919          png_handle_tRNS(png_ptr, info_ptr, length);
 920 #endif
 921
 922 #ifdef PNG_READ_zTXt_SUPPORTED
 923       else if (chunk_name == png_zTXt)
 924          png_handle_zTXt(png_ptr, info_ptr, length);
 925 #endif
 926
 927 #ifdef PNG_READ_iTXt_SUPPORTED
 928       else if (chunk_name == png_iTXt)
 929          png_handle_iTXt(png_ptr, info_ptr, length);
 930 #endif
 931
 932       else
 933          png_handle_unknown(png_ptr, info_ptr, length);
 934    } while (!(png_ptr->mode & PNG_HAVE_IEND));
 935 }
 936 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
 937
 938 /* Free all memory used by the read */
 939 void PNGAPI
 940 png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
 941     png_infopp end_info_ptr_ptr)
 942 {
 943    png_structp png_ptr = NULL;
 944    png_infop info_ptr = NULL, end_info_ptr = NULL;
 945 #ifdef PNG_USER_MEM_SUPPORTED
 946    png_free_ptr free_fn = NULL;
 947    png_voidp mem_ptr = NULL;
 948 #endif
 949
 950    png_debug(1, "in png_destroy_read_struct");
 951
 952    if (png_ptr_ptr != NULL)
 953       png_ptr = *png_ptr_ptr;
 954    if (png_ptr == NULL)
 955       return;
 956
 957 #ifdef PNG_USER_MEM_SUPPORTED
 958    free_fn = png_ptr->free_fn;
 959    mem_ptr = png_ptr->mem_ptr;
 960 #endif
 961
 962    if (info_ptr_ptr != NULL)
 963       info_ptr = *info_ptr_ptr;
 964
 965    if (end_info_ptr_ptr != NULL)
 966       end_info_ptr = *end_info_ptr_ptr;
 967
 968    png_read_destroy(png_ptr, info_ptr, end_info_ptr);
 969
 970    if (info_ptr != NULL)
 971    {
 972 #ifdef PNG_TEXT_SUPPORTED
 973       png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, -1);
 974 #endif
 975
 976 #ifdef PNG_USER_MEM_SUPPORTED
 977       png_destroy_struct_2((png_voidp)info_ptr, (png_free_ptr)free_fn,
 978           (png_voidp)mem_ptr);
 979 #else
 980       png_destroy_struct((png_voidp)info_ptr);
 981 #endif
 982       *info_ptr_ptr = NULL;
 983    }
 984
 985    if (end_info_ptr != NULL)
 986    {
 987 #ifdef PNG_READ_TEXT_SUPPORTED
 988       png_free_data(png_ptr, end_info_ptr, PNG_FREE_TEXT, -1);
 989 #endif
 990 #ifdef PNG_USER_MEM_SUPPORTED
 991       png_destroy_struct_2((png_voidp)end_info_ptr, (png_free_ptr)free_fn,
 992           (png_voidp)mem_ptr);
 993 #else
 994       png_destroy_struct((png_voidp)end_info_ptr);
 995 #endif
 996       *end_info_ptr_ptr = NULL;
 997    }
 998
 999    if (png_ptr != NULL)
1000    {
1001 #ifdef PNG_USER_MEM_SUPPORTED
1002       png_destroy_struct_2((png_voidp)png_ptr, (png_free_ptr)free_fn,
1003           (png_voidp)mem_ptr);
1004 #else
1005       png_destroy_struct((png_voidp)png_ptr);
1006 #endif
1007       *png_ptr_ptr = NULL;
1008    }
1009 }
1010
1011 /* Free all memory used by the read (old method) */
1012 void /* PRIVATE */
1013 png_read_destroy(png_structp png_ptr, png_infop info_ptr,
1014     png_infop end_info_ptr)
1015 {
1016 #ifdef PNG_SETJMP_SUPPORTED
1017    jmp_buf tmp_jmp;
1018 #endif
1019    png_error_ptr error_fn;
1020 #ifdef PNG_WARNINGS_SUPPORTED
1021    png_error_ptr warning_fn;
1022 #endif
1023    png_voidp error_ptr;
1024 #ifdef PNG_USER_MEM_SUPPORTED
1025    png_free_ptr free_fn;
1026 #endif
1027
1028    png_debug(1, "in png_read_destroy");
1029
1030    if (info_ptr != NULL)
1031       png_info_destroy(png_ptr, info_ptr);
1032
1033    if (end_info_ptr != NULL)
1034       png_info_destroy(png_ptr, end_info_ptr);
1035
1036 #ifdef PNG_READ_GAMMA_SUPPORTED
1037    png_destroy_gamma_table(png_ptr);
1038 #endif
1039
1040    png_free(png_ptr, png_ptr->zbuf);
1041    png_free(png_ptr, png_ptr->big_row_buf);
1042    png_free(png_ptr, png_ptr->big_prev_row);
1043    png_free(png_ptr, png_ptr->chunkdata);
1044
1045 #ifdef PNG_READ_QUANTIZE_SUPPORTED
1046    png_free(png_ptr, png_ptr->palette_lookup);
1047    png_free(png_ptr, png_ptr->quantize_index);
1048 #endif
1049
1050    if (png_ptr->free_me & PNG_FREE_PLTE)
1051       png_zfree(png_ptr, png_ptr->palette);
1052    png_ptr->free_me &= ~PNG_FREE_PLTE;
1053
1054 #if defined(PNG_tRNS_SUPPORTED) || \
1055     defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
1056    if (png_ptr->free_me & PNG_FREE_TRNS)
1057       png_free(png_ptr, png_ptr->trans_alpha);
1058    png_ptr->free_me &= ~PNG_FREE_TRNS;
1059 #endif
1060
1061 #ifdef PNG_READ_hIST_SUPPORTED
1062    if (png_ptr->free_me & PNG_FREE_HIST)
1063       png_free(png_ptr, png_ptr->hist);
1064    png_ptr->free_me &= ~PNG_FREE_HIST;
1065 #endif
1066
1067    inflateEnd(&png_ptr->zstream);
1068
1069 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
1070    png_free(png_ptr, png_ptr->save_buffer);
1071 #endif
1072
1073 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
1074 #ifdef PNG_TEXT_SUPPORTED
1075    png_free(png_ptr, png_ptr->current_text);
1076 #endif /* PNG_TEXT_SUPPORTED */
1077 #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
1078
1079    /* Save the important info out of the png_struct, in case it is
1080     * being used again.
1081     */
1082 #ifdef PNG_SETJMP_SUPPORTED
1083    png_memcpy(tmp_jmp, png_ptr->longjmp_buffer, png_sizeof(jmp_buf));
1084 #endif
1085
1086    error_fn = png_ptr->error_fn;
1087 #ifdef PNG_WARNINGS_SUPPORTED
1088    warning_fn = png_ptr->warning_fn;
1089 #endif
1090    error_ptr = png_ptr->error_ptr;
1091 #ifdef PNG_USER_MEM_SUPPORTED
1092    free_fn = png_ptr->free_fn;
1093 #endif
1094
1095    png_memset(png_ptr, 0, png_sizeof(png_struct));
1096
1097    png_ptr->error_fn = error_fn;
1098 #ifdef PNG_WARNINGS_SUPPORTED
1099    png_ptr->warning_fn = warning_fn;
1100 #endif
1101    png_ptr->error_ptr = error_ptr;
1102 #ifdef PNG_USER_MEM_SUPPORTED
1103    png_ptr->free_fn = free_fn;
1104 #endif
1105
1106 #ifdef PNG_SETJMP_SUPPORTED
1107    png_memcpy(png_ptr->longjmp_buffer, tmp_jmp, png_sizeof(jmp_buf));
1108 #endif
1109
1110 }
1111
1112 void PNGAPI
1113 png_set_read_status_fn(png_structp png_ptr, png_read_status_ptr read_row_fn)
1114 {
1115    if (png_ptr == NULL)
1116       return;
1117
1118    png_ptr->read_row_fn = read_row_fn;
1119 }
1120
1121
1122 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1123 #ifdef PNG_INFO_IMAGE_SUPPORTED
1124 void PNGAPI
1125 png_read_png(png_structp png_ptr, png_infop info_ptr,
1126                            int transforms,
1127                            voidp params)
1128 {
1129    int row;
1130
1131    if (png_ptr == NULL || info_ptr == NULL)
1132       return;
1133
1134    /* png_read_info() gives us all of the information from the
1135     * PNG file before the first IDAT (image data chunk).
1136     */
1137    png_read_info(png_ptr, info_ptr);
1138    if (info_ptr->height > PNG_UINT_32_MAX/png_sizeof(png_bytep))
1139       png_error(png_ptr, "Image is too high to process with png_read_png()");
1140
1141    /* -------------- image transformations start here ------------------- */
1142
1143 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1144    /* Tell libpng to strip 16-bit/color files down to 8 bits per color.
1145     */
1146    if (transforms & PNG_TRANSFORM_SCALE_16)
1147    {
1148      /* Added at libpng-1.5.4. "strip_16" produces the same result that it
1149       * did in earlier versions, while "scale_16" is now more accurate.
1150       */
1151       png_set_scale_16(png_ptr);
1152    }
1153 #endif
1154
1155 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1156    /* If both SCALE and STRIP are required pngrtran will effectively cancel the
1157     * latter by doing SCALE first.  This is ok and allows apps not to check for
1158     * which is supported to get the right answer.
1159     */
1160    if (transforms & PNG_TRANSFORM_STRIP_16)
1161       png_set_strip_16(png_ptr);
1162 #endif
1163
1164 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1165    /* Strip alpha bytes from the input data without combining with
1166     * the background (not recommended).
1167     */
1168    if (transforms & PNG_TRANSFORM_STRIP_ALPHA)
1169       png_set_strip_alpha(png_ptr);
1170 #endif
1171
1172 #if defined(PNG_READ_PACK_SUPPORTED) && !defined(PNG_READ_EXPAND_SUPPORTED)
1173    /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single
1174     * byte into separate bytes (useful for paletted and grayscale images).
1175     */
1176    if (transforms & PNG_TRANSFORM_PACKING)
1177       png_set_packing(png_ptr);
1178 #endif
1179
1180 #ifdef PNG_READ_PACKSWAP_SUPPORTED
1181    /* Change the order of packed pixels to least significant bit first
1182     * (not useful if you are using png_set_packing).
1183     */
1184    if (transforms & PNG_TRANSFORM_PACKSWAP)
1185       png_set_packswap(png_ptr);
1186 #endif
1187
1188 #ifdef PNG_READ_EXPAND_SUPPORTED
1189    /* Expand paletted colors into true RGB triplets
1190     * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel
1191     * Expand paletted or RGB images with transparency to full alpha
1192     * channels so the data will be available as RGBA quartets.
1193     */
1194    if (transforms & PNG_TRANSFORM_EXPAND)
1195       if ((png_ptr->bit_depth < 8) ||
1196           (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ||
1197           (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)))
1198          png_set_expand(png_ptr);
1199 #endif
1200
1201    /* We don't handle background color or gamma transformation or quantizing.
1202     */
1203
1204 #ifdef PNG_READ_INVERT_SUPPORTED
1205    /* Invert monochrome files to have 0 as white and 1 as black
1206     */
1207    if (transforms & PNG_TRANSFORM_INVERT_MONO)
1208       png_set_invert_mono(png_ptr);
1209 #endif
1210
1211 #ifdef PNG_READ_SHIFT_SUPPORTED
1212    /* If you want to shift the pixel values from the range [0,255] or
1213     * [0,65535] to the original [0,7] or [0,31], or whatever range the
1214     * colors were originally in:
1215     */
1216    if ((transforms & PNG_TRANSFORM_SHIFT)
1217        && png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT))
1218    {
1219       png_color_8p sig_bit;
1220
1221       png_get_sBIT(png_ptr, info_ptr, &sig_bit);
1222       png_set_shift(png_ptr, sig_bit);
1223    }
1224 #endif
1225
1226 #ifdef PNG_READ_BGR_SUPPORTED
1227    /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
1228    if (transforms & PNG_TRANSFORM_BGR)
1229       png_set_bgr(png_ptr);
1230 #endif
1231
1232 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
1233    /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
1234    if (transforms & PNG_TRANSFORM_SWAP_ALPHA)
1235       png_set_swap_alpha(png_ptr);
1236 #endif
1237
1238 #ifdef PNG_READ_SWAP_SUPPORTED
1239    /* Swap bytes of 16-bit files to least significant byte first */
1240    if (transforms & PNG_TRANSFORM_SWAP_ENDIAN)
1241       png_set_swap(png_ptr);
1242 #endif
1243
1244 /* Added at libpng-1.2.41 */
1245 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1246    /* Invert the alpha channel from opacity to transparency */
1247    if (transforms & PNG_TRANSFORM_INVERT_ALPHA)
1248       png_set_invert_alpha(png_ptr);
1249 #endif
1250
1251 /* Added at libpng-1.2.41 */
1252 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1253    /* Expand grayscale image to RGB */
1254    if (transforms & PNG_TRANSFORM_GRAY_TO_RGB)
1255       png_set_gray_to_rgb(png_ptr);
1256 #endif
1257
1258 /* Added at libpng-1.5.4 */
1259 #ifdef PNG_READ_EXPAND_16_SUPPORTED
1260    if (transforms & PNG_TRANSFORM_EXPAND_16)
1261       png_set_expand_16(png_ptr);
1262 #endif
1263
1264    /* We don't handle adding filler bytes */
1265
1266    /* We use png_read_image and rely on that for interlace handling, but we also
1267     * call png_read_update_info therefore must turn on interlace handling now:
1268     */
1269    (void)png_set_interlace_handling(png_ptr);
1270
1271    /* Optional call to gamma correct and add the background to the palette
1272     * and update info structure.  REQUIRED if you are expecting libpng to
1273     * update the palette for you (i.e., you selected such a transform above).
1274     */
1275    png_read_update_info(png_ptr, info_ptr);
1276
1277    /* -------------- image transformations end here ------------------- */
1278
1279    png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);
1280    if (info_ptr->row_pointers == NULL)
1281    {
1282       png_uint_32 iptr;
1283
1284       info_ptr->row_pointers = (png_bytepp)png_malloc(png_ptr,
1285           info_ptr->height * png_sizeof(png_bytep));
1286       for (iptr=0; iptr<info_ptr->height; iptr++)
1287          info_ptr->row_pointers[iptr] = NULL;
1288
1289       info_ptr->free_me |= PNG_FREE_ROWS;
1290
1291       for (row = 0; row < (int)info_ptr->height; row++)
1292          info_ptr->row_pointers[row] = (png_bytep)png_malloc(png_ptr,
1293             png_get_rowbytes(png_ptr, info_ptr));
1294    }
1295
1296    png_read_image(png_ptr, info_ptr->row_pointers);
1297    info_ptr->valid |= PNG_INFO_IDAT;
1298
1299    /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
1300    png_read_end(png_ptr, info_ptr);
1301
1302    PNG_UNUSED(transforms)   /* Quiet compiler warnings */
1303    PNG_UNUSED(params)
1304
1305 }
1306 #endif /* PNG_INFO_IMAGE_SUPPORTED */
1307 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
1308 #endif /* PNG_READ_SUPPORTED */