/* pngread.c - read a PNG file

 *

 * Last changed in libpng 1.2.53 [February 26, 2015]

 * Copyright (c) 1998-2002,2004,2006-2015 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 code is released under the libpng license.

 * For conditions of distribution and use, see the disclaimer

 * and license in png.h

 *

 * This file contains routines that an application calls directly to

 * read a PNG file or stream.

 */

#define PNG_INTERNAL

#define PNG_NO_PEDANTIC_WARNINGS

#include "png.h"

#ifdef 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 */

#ifdef PNG_SETJMP_SUPPORTED

   volatile

#endif

   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");

#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_USER_LIMITS_SUPPORTED

   png_ptr->user_width_max = PNG_USER_WIDTH_MAX;

   png_ptr->user_height_max = PNG_USER_HEIGHT_MAX;

   /* Added at libpng-1.2.43 and 1.4.0 */

   png_ptr->user_chunk_cache_max = PNG_USER_CHUNK_CACHE_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 /* PNG_SETJMP_SUPPORTED */

#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);

   if (user_png_ver != NULL)

   {

      int found_dots = 0;

      i = -1;

      do

      {

         i++;

         if (user_png_ver[i] != PNG_LIBPNG_VER_STRING[i])

            png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;

         if (user_png_ver[i] == '.')

            found_dots++;

      } while (found_dots < 2 && user_png_ver[i] != 0 &&

            PNG_LIBPNG_VER_STRING[i] != 0);

   }

   else

         png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;

    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_STDIO_SUPPORTED) && !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 /* PNG_SETJMP_SUPPORTED */

   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_STDIO_SUPPORTED) && !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 == NULL || 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");

#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->zstream.zalloc = png_zalloc;

   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_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_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)

{

   png_debug(1, "in png_read_info");

   if (png_ptr == NULL || info_ptr == NULL)

      return;

   /* 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;

#ifdef PNG_READ_bKGD_SUPPORTED

      PNG_CONST PNG_bKGD;

#endif

#ifdef PNG_READ_cHRM_SUPPORTED

      PNG_CONST PNG_cHRM;

#endif

#ifdef PNG_READ_gAMA_SUPPORTED

      PNG_CONST PNG_gAMA;

#endif

#ifdef PNG_READ_hIST_SUPPORTED

      PNG_CONST PNG_hIST;

#endif

#ifdef PNG_READ_iCCP_SUPPORTED

      PNG_CONST PNG_iCCP;

#endif

#ifdef PNG_READ_iTXt_SUPPORTED

      PNG_CONST PNG_iTXt;

#endif

#ifdef PNG_READ_oFFs_SUPPORTED

      PNG_CONST PNG_oFFs;

#endif

#ifdef PNG_READ_pCAL_SUPPORTED

      PNG_CONST PNG_pCAL;

#endif

#ifdef PNG_READ_pHYs_SUPPORTED

      PNG_CONST PNG_pHYs;

#endif

#ifdef PNG_READ_sBIT_SUPPORTED

      PNG_CONST PNG_sBIT;

#endif

#ifdef PNG_READ_sCAL_SUPPORTED

      PNG_CONST PNG_sCAL;

#endif

#ifdef PNG_READ_sPLT_SUPPORTED

      PNG_CONST PNG_sPLT;

#endif

#ifdef PNG_READ_sRGB_SUPPORTED

      PNG_CONST PNG_sRGB;

#endif

#ifdef PNG_READ_tEXt_SUPPORTED

      PNG_CONST PNG_tEXt;

#endif

#ifdef PNG_READ_tIME_SUPPORTED

      PNG_CONST PNG_tIME;

#endif

#ifdef PNG_READ_tRNS_SUPPORTED

      PNG_CONST PNG_tRNS;

#endif

#ifdef PNG_READ_zTXt_SUPPORTED

      PNG_CONST PNG_zTXt;

#endif

#endif /* PNG_USE_LOCAL_ARRAYS */

      png_uint_32 length = png_read_chunk_header(png_ptr);

      PNG_CONST png_bytep chunk_name = png_ptr->chunk_name;

      /* This should be a binary subdivision search or a hash for

       * matching the chunk name rather than a linear search.

       */

      if (!png_memcmp(chunk_name, png_IDAT, 4))

        if (png_ptr->mode & PNG_AFTER_IDAT)

          png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;

      if (!png_memcmp(chunk_name, png_IHDR, 4))

         png_handle_IHDR(png_ptr, info_ptr, length);

      else if (!png_memcmp(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, chunk_name))

      {

         if (!png_memcmp(chunk_name, png_IDAT, 4))

            png_ptr->mode |= PNG_HAVE_IDAT;

         png_handle_unknown(png_ptr, info_ptr, length);

         if (!png_memcmp(chunk_name, png_PLTE, 4))

            png_ptr->mode |= PNG_HAVE_PLTE;

         else if (!png_memcmp(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(chunk_name, png_PLTE, 4))

         png_handle_PLTE(png_ptr, info_ptr, length);

      else if (!png_memcmp(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;

      }

#ifdef PNG_READ_bKGD_SUPPORTED

      else if (!png_memcmp(chunk_name, png_bKGD, 4))

         png_handle_bKGD(png_ptr, info_ptr, length);

#endif

#ifdef PNG_READ_cHRM_SUPPORTED

      else if (!png_memcmp(chunk_name, png_cHRM, 4))

         png_handle_cHRM(png_ptr, info_ptr, length);

#endif

#ifdef PNG_READ_gAMA_SUPPORTED

      else if (!png_memcmp(chunk_name, png_gAMA, 4))

         png_handle_gAMA(png_ptr, info_ptr, length);

#endif

#ifdef PNG_READ_hIST_SUPPORTED

      else if (!png_memcmp(chunk_name, png_hIST, 4))

         png_handle_hIST(png_ptr, info_ptr, length);

#endif

#ifdef PNG_READ_oFFs_SUPPORTED

      else if (!png_memcmp(chunk_name, png_oFFs, 4))

         png_handle_oFFs(png_ptr, info_ptr, length);

#endif

#ifdef PNG_READ_pCAL_SUPPORTED

      else if (!png_memcmp(chunk_name, png_pCAL, 4))

         png_handle_pCAL(png_ptr, info_ptr, length);

#endif

#ifdef PNG_READ_sCAL_SUPPORTED

      else if (!png_memcmp(chunk_name, png_sCAL, 4))

         png_handle_sCAL(png_ptr, info_ptr, length);

#endif

#ifdef PNG_READ_pHYs_SUPPORTED

      else if (!png_memcmp(chunk_name, png_pHYs, 4))

         png_handle_pHYs(png_ptr, info_ptr, length);

#endif

#ifdef PNG_READ_sBIT_SUPPORTED

      else if (!png_memcmp(chunk_name, png_sBIT, 4))

         png_handle_sBIT(png_ptr, info_ptr, length);

#endif

#ifdef PNG_READ_sRGB_SUPPORTED

      else if (!png_memcmp(chunk_name, png_sRGB, 4))

         png_handle_sRGB(png_ptr, info_ptr, length);

#endif

#ifdef PNG_READ_iCCP_SUPPORTED

      else if (!png_memcmp(chunk_name, png_iCCP, 4))

         png_handle_iCCP(png_ptr, info_ptr, length);

#endif

#ifdef PNG_READ_sPLT_SUPPORTED

      else if (!png_memcmp(chunk_name, png_sPLT, 4))

         png_handle_sPLT(png_ptr, info_ptr, length);

#endif

#ifdef PNG_READ_tEXt_SUPPORTED

      else if (!png_memcmp(chunk_name, png_tEXt, 4))

         png_handle_tEXt(png_ptr, info_ptr, length);

#endif

#ifdef PNG_READ_tIME_SUPPORTED

      else if (!png_memcmp(chunk_name, png_tIME, 4))

         png_handle_tIME(png_ptr, info_ptr, length);

#endif

#ifdef PNG_READ_tRNS_SUPPORTED

      else if (!png_memcmp(chunk_name, png_tRNS, 4))

         png_handle_tRNS(png_ptr, info_ptr, length);

#endif

#ifdef PNG_READ_zTXt_SUPPORTED

      else if (!png_memcmp(chunk_name, png_zTXt, 4))

         png_handle_zTXt(png_ptr, info_ptr, length);

#endif

#ifdef PNG_READ_iTXt_SUPPORTED

      else if (!png_memcmp(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_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");

   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);

}

#ifdef PNG_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");

   if (png_ptr == NULL)

      return;

   if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))

      png_read_start_row(png_ptr);

}

#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */

#ifdef PNG_SEQUENTIAL_READ_SUPPORTED

void PNGAPI

png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)

{

#ifndef PNG_USE_GLOBAL_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)",

      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

   }

#ifdef 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_ROWBYTES(png_ptr->pixel_depth,

       png_ptr->iwidth) + 1);

   do

   {

      if (!(png_ptr->zstream.avail_in))

      {

         while (!png_ptr->idat_size)

         {

            png_crc_finish(png_ptr, 0);

            png_ptr->idat_size = png_read_chunk_header(png_ptr);

            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);

#ifdef 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);

#ifdef 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_SEQUENTIAL_READ_SUPPORTED */

#ifdef PNG_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");

   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)