text: 
  /* pngread.c - read a PNG file
   *
   * Last changed in libpng 1.2.20 September 7, 2007
   * For conditions of distribution and use, see copyright notice in png.h
   * Copyright (c) 1998-2007 Glenn Randers-Pehrson
   * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
   * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
   *
   * This file contains routines that an application calls directly to
   * read a PNG file or stream.
   */
  
  #define PNG_INTERNAL
  #include "png.h"
  
  #if defined(PNG_READ_SUPPORTED)
  
  /* Create a PNG structure for reading, and allocate any memory needed. */
  png_structp PNGAPI
  png_create_read_struct(png_const_charp user_png_ver, png_voidp error_ptr,
     png_error_ptr error_fn, png_error_ptr warn_fn)
  {
  
  #ifdef PNG_USER_MEM_SUPPORTED
     return (png_create_read_struct_2(user_png_ver, error_ptr, error_fn,
        warn_fn, png_voidp_NULL, png_malloc_ptr_NULL, png_free_ptr_NULL));
  }
  
  /* Alternate create PNG structure for reading, and allocate any memory needed. */
  png_structp PNGAPI
  png_create_read_struct_2(png_const_charp user_png_ver, png_voidp error_ptr,
     png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
     png_malloc_ptr malloc_fn, png_free_ptr free_fn)
  {
  #endif /* PNG_USER_MEM_SUPPORTED */
  
     png_structp png_ptr;
  
  #ifdef PNG_SETJMP_SUPPORTED
  #ifdef USE_FAR_KEYWORD
     jmp_buf jmpbuf;
  #endif
  #endif
  
     int i;
  
     png_debug(1, "in png_create_read_struct\n");
  #ifdef PNG_USER_MEM_SUPPORTED
     png_ptr = (png_structp)png_create_struct_2(PNG_STRUCT_PNG,
        (png_malloc_ptr)malloc_fn, (png_voidp)mem_ptr);
  #else
     png_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG);
  #endif
     if (png_ptr == NULL)
        return (NULL);
  
     /* added at libpng-1.2.6 */
  #ifdef PNG_SET_USER_LIMITS_SUPPORTED
     png_ptr->user_width_max=PNG_USER_WIDTH_MAX;
     png_ptr->user_height_max=PNG_USER_HEIGHT_MAX;
  #endif
  
  #ifdef PNG_SETJMP_SUPPORTED
  #ifdef USE_FAR_KEYWORD
     if (setjmp(jmpbuf))
  #else
     if (setjmp(png_ptr->jmpbuf))
  #endif
     {
        png_free(png_ptr, png_ptr->zbuf);
        png_ptr->zbuf=NULL;
  #ifdef PNG_USER_MEM_SUPPORTED
        png_destroy_struct_2((png_voidp)png_ptr,
           (png_free_ptr)free_fn, (png_voidp)mem_ptr);
  #else
        png_destroy_struct((png_voidp)png_ptr);
  #endif
        return (NULL);
     }
  #ifdef USE_FAR_KEYWORD
     png_memcpy(png_ptr->jmpbuf,jmpbuf,png_sizeof(jmp_buf));
  #endif
  #endif
  
  #ifdef PNG_USER_MEM_SUPPORTED
     png_set_mem_fn(png_ptr, mem_ptr, malloc_fn, free_fn);
  #endif
  
     png_set_error_fn(png_ptr, error_ptr, error_fn, warn_fn);
  
     i=0;
     do
     {
       if(user_png_ver[i] != png_libpng_ver[i])
          png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
     } while (png_libpng_ver[i++]);
  
     if (png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH)
     {
       /* Libpng 0.90 and later are binary incompatible with libpng 0.89, so
        * we must recompile any applications that use any older library version.
        * For versions after libpng 1.0, we will be compatible, so we need
        * only check the first digit.
        */
       if (user_png_ver == NULL || user_png_ver[0] != png_libpng_ver[0] ||
           (user_png_ver[0] == '1' && user_png_ver[2] != png_libpng_ver[2]) ||
           (user_png_ver[0] == '0' && user_png_ver[2] < '9'))
       {
  #if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
          char msg[80];
          if (user_png_ver)
          {
            png_snprintf(msg, 80,
               "Application was compiled with png.h from libpng-%.20s",
               user_png_ver);
            png_warning(png_ptr, msg);
          }
          png_snprintf(msg, 80,
               "Application  is  running with png.c from libpng-%.20s",
             png_libpng_ver);
          png_warning(png_ptr, msg);
  #endif
  #ifdef PNG_ERROR_NUMBERS_SUPPORTED
          png_ptr->flags=0;
  #endif
          png_error(png_ptr,
             "Incompatible libpng version in application and library");
       }
     }
  
     /* initialize zbuf - compression buffer */
     png_ptr->zbuf_size = PNG_ZBUF_SIZE;
     png_ptr->zbuf = (png_bytep)png_malloc(png_ptr,
       (png_uint_32)png_ptr->zbuf_size);
     png_ptr->zstream.zalloc = png_zalloc;
     png_ptr->zstream.zfree = png_zfree;
     png_ptr->zstream.opaque = (voidpf)png_ptr;
  
     switch (inflateInit(&png_ptr->zstream))
     {
       case Z_OK: /* Do nothing */ break;
       case Z_MEM_ERROR:
       case Z_STREAM_ERROR: png_error(png_ptr, "zlib memory error"); break;
       case Z_VERSION_ERROR: png_error(png_ptr, "zlib version error"); break;
       default: png_error(png_ptr, "Unknown zlib error");
     }
  
     png_ptr->zstream.next_out = png_ptr->zbuf;
     png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
  
     png_set_read_fn(png_ptr, png_voidp_NULL, png_rw_ptr_NULL);
  
  #ifdef PNG_SETJMP_SUPPORTED
  /* Applications that neglect to set up their own setjmp() and then encounter
     a png_error() will longjmp here.  Since the jmpbuf is then meaningless we
     abort instead of returning. */
  #ifdef USE_FAR_KEYWORD
     if (setjmp(jmpbuf))
        PNG_ABORT();
     png_memcpy(png_ptr->jmpbuf,jmpbuf,png_sizeof(jmp_buf));
  #else
     if (setjmp(png_ptr->jmpbuf))
        PNG_ABORT();
  #endif
  #endif
     return (png_ptr);
  }
  
  #if defined(PNG_1_0_X) || defined(PNG_1_2_X)
  /* Initialize PNG structure for reading, and allocate any memory needed.
     This interface is deprecated in favour of the png_create_read_struct(),
     and it will disappear as of libpng-1.3.0. */
  #undef png_read_init
  void PNGAPI
  png_read_init(png_structp png_ptr)
  {
     /* We only come here via pre-1.0.7-compiled applications */
     png_read_init_2(png_ptr, "1.0.6 or earlier", 0, 0);
  }
  
  void PNGAPI
  png_read_init_2(png_structp png_ptr, png_const_charp user_png_ver,
     png_size_t png_struct_size, png_size_t png_info_size)
  {
     /* We only come here via pre-1.0.12-compiled applications */
     if(png_ptr == NULL) return;
  #if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
     if(png_sizeof(png_struct) > png_struct_size ||
        png_sizeof(png_info) > png_info_size)
     {
        char msg[80];
        png_ptr->warning_fn=NULL;
        if (user_png_ver)
        {
          png_snprintf(msg, 80,
             "Application was compiled with png.h from libpng-%.20s",
             user_png_ver);
          png_warning(png_ptr, msg);
        }
        png_snprintf(msg, 80,
           "Application  is  running with png.c from libpng-%.20s",
           png_libpng_ver);
        png_warning(png_ptr, msg);
     }
  #endif
     if(png_sizeof(png_struct) > png_struct_size)
       {
         png_ptr->error_fn=NULL;
  #ifdef PNG_ERROR_NUMBERS_SUPPORTED
         png_ptr->flags=0;
  #endif
         png_error(png_ptr,
         "The png struct allocated by the application for reading is too small.");
       }
     if(png_sizeof(png_info) > png_info_size)
       {
         png_ptr->error_fn=NULL;
  #ifdef PNG_ERROR_NUMBERS_SUPPORTED
         png_ptr->flags=0;
  #endif
         png_error(png_ptr,
           "The info struct allocated by application for reading is too small.");
       }
     png_read_init_3(&png_ptr, user_png_ver, png_struct_size);
  }
  #endif /* PNG_1_0_X || PNG_1_2_X */
  
  void PNGAPI
  png_read_init_3(png_structpp ptr_ptr, png_const_charp user_png_ver,
     png_size_t png_struct_size)
  {
  #ifdef PNG_SETJMP_SUPPORTED
     jmp_buf tmp_jmp;  /* to save current jump buffer */
  #endif
  
     int i=0;
  
     png_structp png_ptr=*ptr_ptr;
  
     if(png_ptr == NULL) return;
  
     do
     {
       if(user_png_ver[i] != png_libpng_ver[i])
       {
  #ifdef PNG_LEGACY_SUPPORTED
         png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
  #else
         png_ptr->warning_fn=NULL;
         png_warning(png_ptr,
          "Application uses deprecated png_read_init() and should be recompiled.");
         break;
  #endif
       }
     } while (png_libpng_ver[i++]);
  
     png_debug(1, "in png_read_init_3\n");
  
  #ifdef PNG_SETJMP_SUPPORTED
     /* save jump buffer and error functions */
     png_memcpy(tmp_jmp, png_ptr->jmpbuf, png_sizeof (jmp_buf));
  #endif
  
     if(png_sizeof(png_struct) > png_struct_size)
       {
         png_destroy_struct(png_ptr);
         *ptr_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG);
         png_ptr = *ptr_ptr;
       }
  
     /* reset all variables to 0 */
     png_memset(png_ptr, 0, png_sizeof (png_struct));
  
  #ifdef PNG_SETJMP_SUPPORTED
     /* restore jump buffer */
     png_memcpy(png_ptr->jmpbuf, tmp_jmp, png_sizeof (jmp_buf));
  #endif
  
     /* added at libpng-1.2.6 */
  #ifdef PNG_SET_USER_LIMITS_SUPPORTED
     png_ptr->user_width_max=PNG_USER_WIDTH_MAX;
     png_ptr->user_height_max=PNG_USER_HEIGHT_MAX;
  #endif
  
     /* initialize zbuf - compression buffer */
     png_ptr->zbuf_size = PNG_ZBUF_SIZE;
     png_ptr->zbuf = (png_bytep)png_malloc(png_ptr,
       (png_uint_32)png_ptr->zbuf_size);
     png_ptr->zstream.zalloc = png_zalloc;
     png_ptr->zstream.zfree = png_zfree;
     png_ptr->zstream.opaque = (voidpf)png_ptr;
  
     switch (inflateInit(&png_ptr->zstream))
     {
       case Z_OK: /* Do nothing */ break;
       case Z_MEM_ERROR:
       case Z_STREAM_ERROR: png_error(png_ptr, "zlib memory"); break;
       case Z_VERSION_ERROR: png_error(png_ptr, "zlib version"); break;
       default: png_error(png_ptr, "Unknown zlib error");
     }
  
     png_ptr->zstream.next_out = png_ptr->zbuf;
     png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
  
     png_set_read_fn(png_ptr, png_voidp_NULL, png_rw_ptr_NULL);
  }
  
  #ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
  /* Read the information before the actual image data.  This has been
   * changed in v0.90 to allow reading a file that already has the magic
   * bytes read from the stream.  You can tell libpng how many bytes have
   * been read from the beginning of the stream (up to the maximum of 8)
   * via png_set_sig_bytes(), and we will only check the remaining bytes
   * here.  The application can then have access to the signature bytes we
   * read if it is determined that this isn't a valid PNG file.
   */
  void PNGAPI
  png_read_info(png_structp png_ptr, png_infop info_ptr)
  {
     if(png_ptr == NULL) return;
     png_debug(1, "in png_read_info\n");
     /* If we haven't checked all of the PNG signature bytes, do so now. */
     if (png_ptr->sig_bytes < 8)
     {
        png_size_t num_checked = png_ptr->sig_bytes,
                   num_to_check = 8 - num_checked;
  
        png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
        png_ptr->sig_bytes = 8;
  
        if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
        {
           if (num_checked < 4 &&
               png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
              png_error(png_ptr, "Not a PNG file");
           else
              png_error(png_ptr, "PNG file corrupted by ASCII conversion");
        }
        if (num_checked < 3)
           png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
     }
  
     for(;;)
     {
  #ifdef PNG_USE_LOCAL_ARRAYS
        PNG_CONST PNG_IHDR;
        PNG_CONST PNG_IDAT;
        PNG_CONST PNG_IEND;
        PNG_CONST PNG_PLTE;
  #if defined(PNG_READ_bKGD_SUPPORTED)
        PNG_CONST PNG_bKGD;
  #endif
  #if defined(PNG_READ_cHRM_SUPPORTED)
        PNG_CONST PNG_cHRM;
  #endif
  #if defined(PNG_READ_gAMA_SUPPORTED)
        PNG_CONST PNG_gAMA;
  #endif
  #if defined(PNG_READ_hIST_SUPPORTED)
        PNG_CONST PNG_hIST;
  #endif
  #if defined(PNG_READ_iCCP_SUPPORTED)
        PNG_CONST PNG_iCCP;
  #endif
  #if defined(PNG_READ_iTXt_SUPPORTED)
        PNG_CONST PNG_iTXt;
  #endif
  #if defined(PNG_READ_oFFs_SUPPORTED)
        PNG_CONST PNG_oFFs;
  #endif
  #if defined(PNG_READ_pCAL_SUPPORTED)
        PNG_CONST PNG_pCAL;
  #endif
  #if defined(PNG_READ_pHYs_SUPPORTED)
        PNG_CONST PNG_pHYs;
  #endif
  #if defined(PNG_READ_sBIT_SUPPORTED)
        PNG_CONST PNG_sBIT;
  #endif
  #if defined(PNG_READ_sCAL_SUPPORTED)
        PNG_CONST PNG_sCAL;
  #endif
  #if defined(PNG_READ_sPLT_SUPPORTED)
        PNG_CONST PNG_sPLT;
  #endif
  #if defined(PNG_READ_sRGB_SUPPORTED)
        PNG_CONST PNG_sRGB;
  #endif
  #if defined(PNG_READ_tEXt_SUPPORTED)
        PNG_CONST PNG_tEXt;
  #endif
  #if defined(PNG_READ_tIME_SUPPORTED)
        PNG_CONST PNG_tIME;
  #endif
  #if defined(PNG_READ_tRNS_SUPPORTED)
        PNG_CONST PNG_tRNS;
  #endif
  #if defined(PNG_READ_zTXt_SUPPORTED)
        PNG_CONST PNG_zTXt;
  #endif
  #endif /* PNG_USE_LOCAL_ARRAYS */
        png_byte chunk_length[4];
        png_uint_32 length;
  
        png_read_data(png_ptr, chunk_length, 4);
        length = png_get_uint_31(png_ptr,chunk_length);
  
        png_reset_crc(png_ptr);
        png_crc_read(png_ptr, png_ptr->chunk_name, 4);
  
        png_debug2(0, "Reading %s chunk, length=%lu.\n", png_ptr->chunk_name,
           length);
  
        /* This should be a binary subdivision search or a hash for
         * matching the chunk name rather than a linear search.
         */
        if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
          if(png_ptr->mode & PNG_AFTER_IDAT)
            png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
  
        if (!png_memcmp(png_ptr->chunk_name, png_IHDR, 4))
           png_handle_IHDR(png_ptr, info_ptr, length);
        else if (!png_memcmp(png_ptr->chunk_name, png_IEND, 4))
           png_handle_IEND(png_ptr, info_ptr, length);
  #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
        else if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name))
        {
           if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
              png_ptr->mode |= PNG_HAVE_IDAT;
           png_handle_unknown(png_ptr, info_ptr, length);
           if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
              png_ptr->mode |= PNG_HAVE_PLTE;
           else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
           {
              if (!(png_ptr->mode & PNG_HAVE_IHDR))
                 png_error(png_ptr, "Missing IHDR before IDAT");
              else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
                       !(png_ptr->mode & PNG_HAVE_PLTE))
                 png_error(png_ptr, "Missing PLTE before IDAT");
              break;
           }
        }
  #endif
        else if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
           png_handle_PLTE(png_ptr, info_ptr, length);
        else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
        {
           if (!(png_ptr->mode & PNG_HAVE_IHDR))
              png_error(png_ptr, "Missing IHDR before IDAT");
           else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
                    !(png_ptr->mode & PNG_HAVE_PLTE))
              png_error(png_ptr, "Missing PLTE before IDAT");
  
           png_ptr->idat_size = length;
           png_ptr->mode |= PNG_HAVE_IDAT;
           break;
        }
  #if defined(PNG_READ_bKGD_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_bKGD, 4))
           png_handle_bKGD(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_cHRM_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_cHRM, 4))
           png_handle_cHRM(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_gAMA_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_gAMA, 4))
           png_handle_gAMA(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_hIST_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_hIST, 4))
           png_handle_hIST(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_oFFs_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_oFFs, 4))
           png_handle_oFFs(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_pCAL_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_pCAL, 4))
           png_handle_pCAL(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_sCAL_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_sCAL, 4))
           png_handle_sCAL(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_pHYs_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_pHYs, 4))
           png_handle_pHYs(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_sBIT_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_sBIT, 4))
           png_handle_sBIT(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_sRGB_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_sRGB, 4))
           png_handle_sRGB(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_iCCP_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_iCCP, 4))
           png_handle_iCCP(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_sPLT_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_sPLT, 4))
           png_handle_sPLT(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_tEXt_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_tEXt, 4))
           png_handle_tEXt(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_tIME_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_tIME, 4))
           png_handle_tIME(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_tRNS_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_tRNS, 4))
           png_handle_tRNS(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_zTXt_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_zTXt, 4))
           png_handle_zTXt(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_iTXt_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_iTXt, 4))
           png_handle_iTXt(png_ptr, info_ptr, length);
  #endif
        else
           png_handle_unknown(png_ptr, info_ptr, length);
     }
  }
  #endif /* PNG_NO_SEQUENTIAL_READ_SUPPORTED */
  
  /* optional call to update the users info_ptr structure */
  void PNGAPI
  png_read_update_info(png_structp png_ptr, png_infop info_ptr)
  {
     png_debug(1, "in png_read_update_info\n");
     if(png_ptr == NULL) return;
     if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
        png_read_start_row(png_ptr);
     else
        png_warning(png_ptr,
        "Ignoring extra png_read_update_info() call; row buffer not reallocated");
     png_read_transform_info(png_ptr, info_ptr);
  }
  
  #ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
  /* Initialize palette, background, etc, after transformations
   * are set, but before any reading takes place.  This allows
   * the user to obtain a gamma-corrected palette, for example.
   * If the user doesn't call this, we will do it ourselves.
   */
  void PNGAPI
  png_start_read_image(png_structp png_ptr)
  {
     png_debug(1, "in png_start_read_image\n");
     if(png_ptr == NULL) return;
     if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
        png_read_start_row(png_ptr);
  }
  #endif /* PNG_NO_SEQUENTIAL_READ_SUPPORTED */
  
  #ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
  void PNGAPI
  png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
  {
  #ifdef PNG_USE_LOCAL_ARRAYS
     PNG_CONST PNG_IDAT;
     PNG_CONST int png_pass_dsp_mask[7] = {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55,
       0xff};
     PNG_CONST int png_pass_mask[7] = {0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff};
  #endif
     int ret;
     if(png_ptr == NULL) return;
     png_debug2(1, "in png_read_row (row %lu, pass %d)\n",
        png_ptr->row_number, png_ptr->pass);
     if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
        png_read_start_row(png_ptr);
     if (png_ptr->row_number == 0 && png_ptr->pass == 0)
     {
     /* check for transforms that have been set but were defined out */
  #if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED)
     if (png_ptr->transformations & PNG_INVERT_MONO)
        png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined.");
  #endif
  #if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED)
     if (png_ptr->transformations & PNG_FILLER)
        png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined.");
  #endif
  #if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && !defined(PNG_READ_PACKSWAP_SUPPORTED)
     if (png_ptr->transformations & PNG_PACKSWAP)
        png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined.");
  #endif
  #if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED)
     if (png_ptr->transformations & PNG_PACK)
        png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined.");
  #endif
  #if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED)
     if (png_ptr->transformations & PNG_SHIFT)
        png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined.");
  #endif
  #if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED)
     if (png_ptr->transformations & PNG_BGR)
        png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined.");
  #endif
  #if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED)
     if (png_ptr->transformations & PNG_SWAP_BYTES)
        png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined.");
  #endif
     }
  
  #if defined(PNG_READ_INTERLACING_SUPPORTED)
     /* if interlaced and we do not need a new row, combine row and return */
     if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
     {
        switch (png_ptr->pass)
        {
           case 0:
              if (png_ptr->row_number & 0x07)
              {
                 if (dsp_row != NULL)
                    png_combine_row(png_ptr, dsp_row,
                       png_pass_dsp_mask[png_ptr->pass]);
                 png_read_finish_row(png_ptr);
                 return;
              }
              break;
           case 1:
              if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
              {
                 if (dsp_row != NULL)
                    png_combine_row(png_ptr, dsp_row,
                       png_pass_dsp_mask[png_ptr->pass]);
                 png_read_finish_row(png_ptr);
                 return;
              }
              break;
           case 2:
              if ((png_ptr->row_number & 0x07) != 4)
              {
                 if (dsp_row != NULL && (png_ptr->row_number & 4))
                    png_combine_row(png_ptr, dsp_row,
                       png_pass_dsp_mask[png_ptr->pass]);
                 png_read_finish_row(png_ptr);
                 return;
              }
              break;
           case 3:
              if ((png_ptr->row_number & 3) || png_ptr->width < 3)
              {
                 if (dsp_row != NULL)
                    png_combine_row(png_ptr, dsp_row,
                       png_pass_dsp_mask[png_ptr->pass]);
                 png_read_finish_row(png_ptr);
                 return;
              }
              break;
           case 4:
              if ((png_ptr->row_number & 3) != 2)
              {
                 if (dsp_row != NULL && (png_ptr->row_number & 2))
                    png_combine_row(png_ptr, dsp_row,
                       png_pass_dsp_mask[png_ptr->pass]);
                 png_read_finish_row(png_ptr);
                 return;
              }
              break;
           case 5:
              if ((png_ptr->row_number & 1) || png_ptr->width < 2)
              {
                 if (dsp_row != NULL)
                    png_combine_row(png_ptr, dsp_row,
                       png_pass_dsp_mask[png_ptr->pass]);
                 png_read_finish_row(png_ptr);
                 return;
              }
              break;
           case 6:
              if (!(png_ptr->row_number & 1))
              {
                 png_read_finish_row(png_ptr);
                 return;
              }
              break;
        }
     }
  #endif
  
     if (!(png_ptr->mode & PNG_HAVE_IDAT))
        png_error(png_ptr, "Invalid attempt to read row data");
  
     png_ptr->zstream.next_out = png_ptr->row_buf;
     png_ptr->zstream.avail_out = (uInt)png_ptr->irowbytes;
     do
     {
        if (!(png_ptr->zstream.avail_in))
        {
           while (!png_ptr->idat_size)
           {
              png_byte chunk_length[4];
  
              png_crc_finish(png_ptr, 0);
  
              png_read_data(png_ptr, chunk_length, 4);
              png_ptr->idat_size = png_get_uint_31(png_ptr,chunk_length);
  
              png_reset_crc(png_ptr);
              png_crc_read(png_ptr, png_ptr->chunk_name, 4);
              if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
                 png_error(png_ptr, "Not enough image data");
           }
           png_ptr->zstream.avail_in = (uInt)png_ptr->zbuf_size;
           png_ptr->zstream.next_in = png_ptr->zbuf;
           if (png_ptr->zbuf_size > png_ptr->idat_size)
              png_ptr->zstream.avail_in = (uInt)png_ptr->idat_size;
           png_crc_read(png_ptr, png_ptr->zbuf,
              (png_size_t)png_ptr->zstream.avail_in);
           png_ptr->idat_size -= png_ptr->zstream.avail_in;
        }
        ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
        if (ret == Z_STREAM_END)
        {
           if (png_ptr->zstream.avail_out || png_ptr->zstream.avail_in ||
              png_ptr->idat_size)
              png_error(png_ptr, "Extra compressed data");
           png_ptr->mode |= PNG_AFTER_IDAT;
           png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
           break;
        }
        if (ret != Z_OK)
           png_error(png_ptr, png_ptr->zstream.msg ? png_ptr->zstream.msg :
                     "Decompression error");
  
     } while (png_ptr->zstream.avail_out);
  
     png_ptr->row_info.color_type = png_ptr->color_type;
     png_ptr->row_info.width = png_ptr->iwidth;
     png_ptr->row_info.channels = png_ptr->channels;
     png_ptr->row_info.bit_depth = png_ptr->bit_depth;
     png_ptr->row_info.pixel_depth = png_ptr->pixel_depth;
     png_ptr->row_info.rowbytes = PNG_ROWBYTES(png_ptr->row_info.pixel_depth,
         png_ptr->row_info.width);
  
     if(png_ptr->row_buf[0])
     png_read_filter_row(png_ptr, &(png_ptr->row_info),
        png_ptr->row_buf + 1, png_ptr->prev_row + 1,
        (int)(png_ptr->row_buf[0]));
  
     png_memcpy_check(png_ptr, png_ptr->prev_row, png_ptr->row_buf,
        png_ptr->rowbytes + 1);
  
  #if defined(PNG_MNG_FEATURES_SUPPORTED)
     if((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
        (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
     {
        /* Intrapixel differencing */
        png_do_read_intrapixel(&(png_ptr->row_info), png_ptr->row_buf + 1);
     }
  #endif
  
  
     if (png_ptr->transformations || (png_ptr->flags&PNG_FLAG_STRIP_ALPHA))
        png_do_read_transformations(png_ptr);
  
  #if defined(PNG_READ_INTERLACING_SUPPORTED)
     /* blow up interlaced rows to full size */
     if (png_ptr->interlaced &&
        (png_ptr->transformations & PNG_INTERLACE))
     {
        if (png_ptr->pass < 6)
  /*       old interface (pre-1.0.9):
           png_do_read_interlace(&(png_ptr->row_info),
              png_ptr->row_buf + 1, png_ptr->pass, png_ptr->transformations);
   */
           png_do_read_interlace(png_ptr);
  
        if (dsp_row != NULL)
           png_combine_row(png_ptr, dsp_row,
              png_pass_dsp_mask[png_ptr->pass]);
        if (row != NULL)
           png_combine_row(png_ptr, row,
              png_pass_mask[png_ptr->pass]);
     }
     else
  #endif
     {
        if (row != NULL)
           png_combine_row(png_ptr, row, 0xff);
        if (dsp_row != NULL)
           png_combine_row(png_ptr, dsp_row, 0xff);
     }
     png_read_finish_row(png_ptr);
  
     if (png_ptr->read_row_fn != NULL)
        (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
  }
  #endif /* PNG_NO_SEQUENTIAL_READ_SUPPORTED */
  
  #ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
  /* Read one or more rows of image data.  If the image is interlaced,
   * and png_set_interlace_handling() has been called, the rows need to
   * contain the contents of the rows from the previous pass.  If the
   * image has alpha or transparency, and png_handle_alpha()[*] has been
   * called, the rows contents must be initialized to the contents of the
   * screen.
   *
   * "row" holds the actual image, and pixels are placed in it
   * as they arrive.  If the image is displayed after each pass, it will
   * appear to "sparkle" in.  "display_row" can be used to display a
   * "chunky" progressive image, with finer detail added as it becomes
   * available.  If you do not want this "chunky" display, you may pass
   * NULL for display_row.  If you do not want the sparkle display, and
   * you have not called png_handle_alpha(), you may pass NULL for rows.
   * If you have called png_handle_alpha(), and the image has either an
   * alpha channel or a transparency chunk, you must provide a buffer for
   * rows.  In this case, you do not have to provide a display_row buffer
   * also, but you may.  If the image is not interlaced, or if you have
   * not called png_set_interlace_handling(), the display_row buffer will
   * be ignored, so pass NULL to it.
   *
   * [*] png_handle_alpha() does not exist yet, as of this version of libpng
   */
  
  void PNGAPI
  png_read_rows(png_structp png_ptr, png_bytepp row,
     png_bytepp display_row, png_uint_32 num_rows)
  {
     png_uint_32 i;
     png_bytepp rp;
     png_bytepp dp;
  
     png_debug(1, "in png_read_rows\n");
     if(png_ptr == NULL) return;
     rp = row;
     dp = display_row;
     if (rp != NULL && dp != NULL)
        for (i = 0; i < num_rows; i++)
        {
           png_bytep rptr = *rp++;
           png_bytep dptr = *dp++;
  
           png_read_row(png_ptr, rptr, dptr);
        }
     else if(rp != NULL)
        for (i = 0; i < num_rows; i++)
        {
           png_bytep rptr = *rp;
           png_read_row(png_ptr, rptr, png_bytep_NULL);
           rp++;
        }
     else if(dp != NULL)
        for (i = 0; i < num_rows; i++)
        {
           png_bytep dptr = *dp;
           png_read_row(png_ptr, png_bytep_NULL, dptr);
           dp++;
        }
  }
  #endif /* PNG_NO_SEQUENTIAL_READ_SUPPORTED */
  
  #ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
  /* Read the entire image.  If the image has an alpha channel or a tRNS
   * chunk, and you have called png_handle_alpha()[*], you will need to
   * initialize the image to the current image that PNG will be overlaying.
   * We set the num_rows again here, in case it was incorrectly set in
   * png_read_start_row() by a call to png_read_update_info() or
   * png_start_read_image() if png_set_interlace_handling() wasn't called
   * prior to either of these functions like it should have been.  You can
   * only call this function once.  If you desire to have an image for
   * each pass of a interlaced image, use png_read_rows() instead.
   *
   * [*] png_handle_alpha() does not exist yet, as of this version of libpng
   */
  void PNGAPI
  png_read_image(png_structp png_ptr, png_bytepp image)
  {
     png_uint_32 i,image_height;
     int pass, j;
     png_bytepp rp;
  
     png_debug(1, "in png_read_image\n");
     if(png_ptr == NULL) return;
  
  #ifdef PNG_READ_INTERLACING_SUPPORTED
     pass = png_set_interlace_handling(png_ptr);
  #else
     if (png_ptr->interlaced)
        png_error(png_ptr,
          "Cannot read interlaced image -- interlace handler disabled.");
     pass = 1;
  #endif
  
  
     image_height=png_ptr->height;
     png_ptr->num_rows = image_height; /* Make sure this is set correctly */
  
     for (j = 0; j < pass; j++)
     {
        rp = image;
        for (i = 0; i < image_height; i++)
        {
           png_read_row(png_ptr, *rp, png_bytep_NULL);
           rp++;
        }
     }
  }
  #endif /* PNG_NO_SEQUENTIAL_READ_SUPPORTED */
  
  #ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
  /* Read the end of the PNG file.  Will not read past the end of the
   * file, will verify the end is accurate, and will read any comments
   * or time information at the end of the file, if info is not NULL.
   */
  void PNGAPI
  png_read_end(png_structp png_ptr, png_infop info_ptr)
  {
     png_byte chunk_length[4];
     png_uint_32 length;
  
     png_debug(1, "in png_read_end\n");
     if(png_ptr == NULL) return;
     png_crc_finish(png_ptr, 0); /* Finish off CRC from last IDAT chunk */
  
     do
     {
  #ifdef PNG_USE_LOCAL_ARRAYS
        PNG_CONST PNG_IHDR;
        PNG_CONST PNG_IDAT;
        PNG_CONST PNG_IEND;
        PNG_CONST PNG_PLTE;
  #if defined(PNG_READ_bKGD_SUPPORTED)
        PNG_CONST PNG_bKGD;
  #endif
  #if defined(PNG_READ_cHRM_SUPPORTED)
        PNG_CONST PNG_cHRM;
  #endif
  #if defined(PNG_READ_gAMA_SUPPORTED)
        PNG_CONST PNG_gAMA;
  #endif
  #if defined(PNG_READ_hIST_SUPPORTED)
        PNG_CONST PNG_hIST;
  #endif
  #if defined(PNG_READ_iCCP_SUPPORTED)
        PNG_CONST PNG_iCCP;
  #endif
  #if defined(PNG_READ_iTXt_SUPPORTED)
        PNG_CONST PNG_iTXt;
  #endif
  #if defined(PNG_READ_oFFs_SUPPORTED)
        PNG_CONST PNG_oFFs;
  #endif
  #if defined(PNG_READ_pCAL_SUPPORTED)
        PNG_CONST PNG_pCAL;
  #endif
  #if defined(PNG_READ_pHYs_SUPPORTED)
        PNG_CONST PNG_pHYs;
  #endif
  #if defined(PNG_READ_sBIT_SUPPORTED)
        PNG_CONST PNG_sBIT;
  #endif
  #if defined(PNG_READ_sCAL_SUPPORTED)
        PNG_CONST PNG_sCAL;
  #endif
  #if defined(PNG_READ_sPLT_SUPPORTED)
        PNG_CONST PNG_sPLT;
  #endif
  #if defined(PNG_READ_sRGB_SUPPORTED)
        PNG_CONST PNG_sRGB;
  #endif
  #if defined(PNG_READ_tEXt_SUPPORTED)
        PNG_CONST PNG_tEXt;
  #endif
  #if defined(PNG_READ_tIME_SUPPORTED)
        PNG_CONST PNG_tIME;
  #endif
  #if defined(PNG_READ_tRNS_SUPPORTED)
        PNG_CONST PNG_tRNS;
  #endif
  #if defined(PNG_READ_zTXt_SUPPORTED)
        PNG_CONST PNG_zTXt;
  #endif
  #endif /* PNG_USE_LOCAL_ARRAYS */
  
        png_read_data(png_ptr, chunk_length, 4);
        length = png_get_uint_31(png_ptr,chunk_length);
  
        png_reset_crc(png_ptr);
        png_crc_read(png_ptr, png_ptr->chunk_name, 4);
  
        png_debug1(0, "Reading %s chunk.\n", png_ptr->chunk_name);
  
        if (!png_memcmp(png_ptr->chunk_name, png_IHDR, 4))
           png_handle_IHDR(png_ptr, info_ptr, length);
        else if (!png_memcmp(png_ptr->chunk_name, png_IEND, 4))
           png_handle_IEND(png_ptr, info_ptr, length);
  #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
        else if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name))
        {
           if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
           {
              if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
                 png_error(png_ptr, "Too many IDAT's found");
           }
           png_handle_unknown(png_ptr, info_ptr, length);
           if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
              png_ptr->mode |= PNG_HAVE_PLTE;
        }
  #endif
        else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
        {
           /* Zero length IDATs are legal after the last IDAT has been
            * read, but not after other chunks have been read.
            */
           if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
              png_error(png_ptr, "Too many IDAT's found");
           png_crc_finish(png_ptr, length);
        }
        else if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
           png_handle_PLTE(png_ptr, info_ptr, length);
  #if defined(PNG_READ_bKGD_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_bKGD, 4))
           png_handle_bKGD(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_cHRM_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_cHRM, 4))
           png_handle_cHRM(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_gAMA_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_gAMA, 4))
           png_handle_gAMA(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_hIST_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_hIST, 4))
           png_handle_hIST(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_oFFs_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_oFFs, 4))
           png_handle_oFFs(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_pCAL_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_pCAL, 4))
           png_handle_pCAL(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_sCAL_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_sCAL, 4))
           png_handle_sCAL(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_pHYs_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_pHYs, 4))
           png_handle_pHYs(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_sBIT_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_sBIT, 4))
           png_handle_sBIT(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_sRGB_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_sRGB, 4))
           png_handle_sRGB(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_iCCP_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_iCCP, 4))
           png_handle_iCCP(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_sPLT_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_sPLT, 4))
           png_handle_sPLT(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_tEXt_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_tEXt, 4))
           png_handle_tEXt(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_tIME_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_tIME, 4))
           png_handle_tIME(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_tRNS_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_tRNS, 4))
           png_handle_tRNS(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_zTXt_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_zTXt, 4))
           png_handle_zTXt(png_ptr, info_ptr, length);
  #endif
  #if defined(PNG_READ_iTXt_SUPPORTED)
        else if (!png_memcmp(png_ptr->chunk_name, png_iTXt, 4))
           png_handle_iTXt(png_ptr, info_ptr, length);
  #endif
        else
           png_handle_unknown(png_ptr, info_ptr, length);
     } while (!(png_ptr->mode & PNG_HAVE_IEND));
  }
  #endif /* PNG_NO_SEQUENTIAL_READ_SUPPORTED */
  
  /* free all memory used by the read */
  void PNGAPI
  png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
     png_infopp end_info_ptr_ptr)
  {
     png_structp png_ptr = NULL;
     png_infop info_ptr = NULL, end_info_ptr = NULL;
  #ifdef PNG_USER_MEM_SUPPORTED
     png_free_ptr free_fn;
     png_voidp mem_ptr;
  #endif
  
     png_debug(1, "in png_destroy_read_struct\n");
     if (png_ptr_ptr != NULL)
        png_ptr = *png_ptr_ptr;
  
     if (info_ptr_ptr != NULL)
        info_ptr = *info_ptr_ptr;
  
     if (end_info_ptr_ptr != NULL)
        end_info_ptr = *end_info_ptr_ptr;
  
  #ifdef PNG_USER_MEM_SUPPORTED
     free_fn = png_ptr->free_fn;
     mem_ptr = png_ptr->mem_ptr;
  #endif
  
     png_read_destroy(png_ptr, info_ptr, end_info_ptr);
  
     if (info_ptr != NULL)
     {
  #if defined(PNG_TEXT_SUPPORTED)
        png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, -1);
  #endif
  
  #ifdef PNG_USER_MEM_SUPPORTED
        png_destroy_struct_2((png_voidp)info_ptr, (png_free_ptr)free_fn,
            (png_voidp)mem_ptr);
  #else
        png_destroy_struct((png_voidp)info_ptr);
  #endif
        *info_ptr_ptr = NULL;
     }
  
     if (end_info_ptr != NULL)
     {
  #if defined(PNG_READ_TEXT_SUPPORTED)
        png_free_data(png_ptr, end_info_ptr, PNG_FREE_TEXT, -1);
  #endif
  #ifdef PNG_USER_MEM_SUPPORTED
        png_destroy_struct_2((png_voidp)end_info_ptr, (png_free_ptr)free_fn,
           (png_voidp)mem_ptr);
  #else
        png_destroy_struct((png_voidp)end_info_ptr);
  #endif
        *end_info_ptr_ptr = NULL;
     }
  
     if (png_ptr != NULL)
     {
  #ifdef PNG_USER_MEM_SUPPORTED
        png_destroy_struct_2((png_voidp)png_ptr, (png_free_ptr)free_fn,
            (png_voidp)mem_ptr);
  #else
        png_destroy_struct((png_voidp)png_ptr);
  #endif
        *png_ptr_ptr = NULL;
     }
  }
  
  /* free all memory used by the read (old method) */
  void /* PRIVATE */
  png_read_destroy(png_structp png_ptr, png_infop info_ptr, png_infop end_info_ptr)
  {
  #ifdef PNG_SETJMP_SUPPORTED
     jmp_buf tmp_jmp;
  #endif
     png_error_ptr error_fn;
     png_error_ptr warning_fn;
     png_voidp error_ptr;
  #ifdef PNG_USER_MEM_SUPPORTED
     png_free_ptr free_fn;
  #endif
  
     png_debug(1, "in png_read_destroy\n");
     if (info_ptr != NULL)
        png_info_destroy(png_ptr, info_ptr);
  
     if (end_info_ptr != NULL)
        png_info_destroy(png_ptr, end_info_ptr);
  
     png_free(png_ptr, png_ptr->zbuf);
     png_free(png_ptr, png_ptr->big_row_buf);
     png_free(png_ptr, png_ptr->prev_row);
  #if defined(PNG_READ_DITHER_SUPPORTED)
     png_free(png_ptr, png_ptr->palette_lookup);
     png_free(png_ptr, png_ptr->dither_index);
  #endif
  #if defined(PNG_READ_GAMMA_SUPPORTED)
     png_free(png_ptr, png_ptr->gamma_table);
  #endif
  #if defined(PNG_READ_BACKGROUND_SUPPORTED)
     png_free(png_ptr, png_ptr->gamma_from_1);
     png_free(png_ptr, png_ptr->gamma_to_1);
  #endif
  #ifdef PNG_FREE_ME_SUPPORTED
     if (png_ptr->free_me & PNG_FREE_PLTE)
        png_zfree(png_ptr, png_ptr->palette);
     png_ptr->free_me &= ~PNG_FREE_PLTE;
  #else
     if (png_ptr->flags & PNG_FLAG_FREE_PLTE)
        png_zfree(png_ptr, png_ptr->palette);
     png_ptr->flags &= ~PNG_FLAG_FREE_PLTE;
  #endif
  #if defined(PNG_tRNS_SUPPORTED) || \
      defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
  #ifdef PNG_FREE_ME_SUPPORTED
     if (png_ptr->free_me & PNG_FREE_TRNS)
        png_free(png_ptr, png_ptr->trans);
     png_ptr->free_me &= ~PNG_FREE_TRNS;
  #else
     if (png_ptr->flags & PNG_FLAG_FREE_TRNS)
        png_free(png_ptr, png_ptr->trans);
     png_ptr->flags &= ~PNG_FLAG_FREE_TRNS;
  #endif
  #endif
  #if defined(PNG_READ_hIST_SUPPORTED)
  #ifdef PNG_FREE_ME_SUPPORTED
     if (png_ptr->free_me & PNG_FREE_HIST)
        png_free(png_ptr, png_ptr->hist);
     png_ptr->free_me &= ~PNG_FREE_HIST;
  #else
     if (png_ptr->flags & PNG_FLAG_FREE_HIST)
        png_free(png_ptr, png_ptr->hist);
     png_ptr->flags &= ~PNG_FLAG_FREE_HIST;
  #endif
  #endif
  #if defined(PNG_READ_GAMMA_SUPPORTED)
     if (png_ptr->gamma_16_table != NULL)
     {
        int i;
        int istop = (1 << (8 - png_ptr->gamma_shift));
        for (i = 0; i < istop; i++)
        {
           png_free(png_ptr, png_ptr->gamma_16_table[i]);
        }
     png_free(png_ptr, png_ptr->gamma_16_table);
     }
  #if defined(PNG_READ_BACKGROUND_SUPPORTED)
     if (png_ptr->gamma_16_from_1 != NULL)
     {
        int i;
        int istop = (1 << (8 - png_ptr->gamma_shift));
        for (i = 0; i < istop; i++)
        {
           png_free(png_ptr, png_ptr->gamma_16_from_1[i]);
        }
     png_free(png_ptr, png_ptr->gamma_16_from_1);
     }
     if (png_ptr->gamma_16_to_1 != NULL)
     {
        int i;
        int istop = (1 << (8 - png_ptr->gamma_shift));
        for (i = 0; i < istop; i++)
        {
           png_free(png_ptr, png_ptr->gamma_16_to_1[i]);
        }
     png_free(png_ptr, png_ptr->gamma_16_to_1);
     }
  #endif
  #endif
  #if defined(PNG_TIME_RFC1123_SUPPORTED)
     png_free(png_ptr, png_ptr->time_buffer);
  #endif
  
     inflateEnd(&png_ptr->zstream);
  #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
     png_free(png_ptr, png_ptr->save_buffer);
  #endif
  
  #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
  #ifdef PNG_TEXT_SUPPORTED
     png_free(png_ptr, png_ptr->current_text);
  #endif /* PNG_TEXT_SUPPORTED */
  #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
  
     /* Save the important info out of the png_struct, in case it is
      * being used again.
      */
  #ifdef PNG_SETJMP_SUPPORTED
     png_memcpy(tmp_jmp, png_ptr->jmpbuf, png_sizeof (jmp_buf));
  #endif
  
     error_fn = png_ptr->error_fn;
     warning_fn = png_ptr->warning_fn;
     error_ptr = png_ptr->error_ptr;
  #ifdef PNG_USER_MEM_SUPPORTED
     free_fn = png_ptr->free_fn;
  #endif
  
     png_memset(png_ptr, 0, png_sizeof (png_struct));
  
     png_ptr->error_fn = error_fn;
     png_ptr->warning_fn = warning_fn;
     png_ptr->error_ptr = error_ptr;
  #ifdef PNG_USER_MEM_SUPPORTED
     png_ptr->free_fn = free_fn;
  #endif
  
  #ifdef PNG_SETJMP_SUPPORTED
     png_memcpy(png_ptr->jmpbuf, tmp_jmp, png_sizeof (jmp_buf));
  #endif
  
  }
  
  void PNGAPI
  png_set_read_status_fn(png_structp png_ptr, png_read_status_ptr read_row_fn)
  {
     if(png_ptr == NULL) return;
     png_ptr->read_row_fn = read_row_fn;
  }
  
  
  #ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
  #if defined(PNG_INFO_IMAGE_SUPPORTED)
  void PNGAPI
  png_read_png(png_structp png_ptr, png_infop info_ptr,
                             int transforms,
                             voidp params)
  {
     int row;
  
     if(png_ptr == NULL) return;
  #if defined(PNG_READ_INVERT_ALPHA_SUPPORTED)
     /* invert the alpha channel from opacity to transparency
      */
     if (transforms & PNG_TRANSFORM_INVERT_ALPHA)
         png_set_invert_alpha(png_ptr);
  #endif
  
     /* png_read_info() gives us all of the information from the
      * PNG file before the first IDAT (image data chunk).
      */
     png_read_info(png_ptr, info_ptr);
     if (info_ptr->height > PNG_UINT_32_MAX/png_sizeof(png_bytep))
        png_error(png_ptr,"Image is too high to process with png_read_png()");
  
     /* -------------- image transformations start here ------------------- */
  
  #if defined(PNG_READ_16_TO_8_SUPPORTED)
     /* tell libpng to strip 16 bit/color files down to 8 bits per color
      */
     if (transforms & PNG_TRANSFORM_STRIP_16)
         png_set_strip_16(png_ptr);
  #endif
  
  #if defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
     /* Strip alpha bytes from the input data without combining with
      * the background (not recommended).
      */
     if (transforms & PNG_TRANSFORM_STRIP_ALPHA)
         png_set_strip_alpha(png_ptr);
  #endif
  
  #if defined(PNG_READ_PACK_SUPPORTED) && !defined(PNG_READ_EXPAND_SUPPORTED)
     /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single
      * byte into separate bytes (useful for paletted and grayscale images).
      */
     if (transforms & PNG_TRANSFORM_PACKING)
         png_set_packing(png_ptr);
  #endif
  
  #if defined(PNG_READ_PACKSWAP_SUPPORTED)
     /* Change the order of packed pixels to least significant bit first
      * (not useful if you are using png_set_packing).
      */
     if (transforms & PNG_TRANSFORM_PACKSWAP)
         png_set_packswap(png_ptr);
  #endif
  
  #if defined(PNG_READ_EXPAND_SUPPORTED)
     /* Expand paletted colors into true RGB triplets
      * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel
      * Expand paletted or RGB images with transparency to full alpha
      * channels so the data will be available as RGBA quartets.
      */
     if (transforms & PNG_TRANSFORM_EXPAND)
         if ((png_ptr->bit_depth < 8) ||
             (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ||
             (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)))
           png_set_expand(png_ptr);
  #endif
  
     /* We don't handle background color or gamma transformation or dithering.
      */
  
  #if defined(PNG_READ_INVERT_SUPPORTED)
     /* invert monochrome files to have 0 as white and 1 as black
      */
     if (transforms & PNG_TRANSFORM_INVERT_MONO)
         png_set_invert_mono(png_ptr);
  #endif
  
  #if defined(PNG_READ_SHIFT_SUPPORTED)
     /* If you want to shift the pixel values from the range [0,255] or
      * [0,65535] to the original [0,7] or [0,31], or whatever range the
      * colors were originally in:
      */
     if ((transforms & PNG_TRANSFORM_SHIFT)
         && png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT))
     {
        png_color_8p sig_bit;
  
        png_get_sBIT(png_ptr, info_ptr, &sig_bit);
        png_set_shift(png_ptr, sig_bit);
     }
  #endif
  
  #if defined(PNG_READ_BGR_SUPPORTED)
     /* flip the RGB pixels to BGR (or RGBA to BGRA)
      */
     if (transforms & PNG_TRANSFORM_BGR)
         png_set_bgr(png_ptr);
  #endif
  
  #if defined(PNG_READ_SWAP_ALPHA_SUPPORTED)
     /* swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR)
      */
     if (transforms & PNG_TRANSFORM_SWAP_ALPHA)
         png_set_swap_alpha(png_ptr);
  #endif
  
  #if defined(PNG_READ_SWAP_SUPPORTED)
     /* swap bytes of 16 bit files to least significant byte first
      */
     if (transforms & PNG_TRANSFORM_SWAP_ENDIAN)
         png_set_swap(png_ptr);
  #endif
  
     /* We don't handle adding filler bytes */
  
     /* Optional call to gamma correct and add the background to the palette
      * and update info structure.  REQUIRED if you are expecting libpng to
      * update the palette for you (i.e., you selected such a transform above).
      */
     png_read_update_info(png_ptr, info_ptr);
  
     /* -------------- image transformations end here ------------------- */
  
  #ifdef PNG_FREE_ME_SUPPORTED
     png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);
  #endif
     if(info_ptr->row_pointers == NULL)
     {
        info_ptr->row_pointers = (png_bytepp)png_malloc(png_ptr,
           info_ptr->height * png_sizeof(png_bytep));
  #ifdef PNG_FREE_ME_SUPPORTED
        info_ptr->free_me |= PNG_FREE_ROWS;
  #endif
        for (row = 0; row < (int)info_ptr->height; row++)
        {
           info_ptr->row_pointers[row] = (png_bytep)png_malloc(png_ptr,
              png_get_rowbytes(png_ptr, info_ptr));
        }
     }
  
     png_read_image(png_ptr, info_ptr->row_pointers);
     info_ptr->valid |= PNG_INFO_IDAT;
  
     /* read rest of file, and get additional chunks in info_ptr - REQUIRED */
     png_read_end(png_ptr, info_ptr);
  
     (void) transforms; /* quiet compiler warnings */
     (void) params;
  
  }
  #endif /* PNG_INFO_IMAGE_SUPPORTED */
  #endif /* PNG_NO_SEQUENTIAL_READ_SUPPORTED */
  #endif /* PNG_READ_SUPPORTED */
  