// pngimage.cpp -- image data from png file
//
// Written by Frederic Bouvier, started March 2004.
//
// Copyright (C) 2004  Frederic Bouvier - fredb@users.sourceforge.net
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
//
// $Id: pngimage.cpp,v 1.2 2005/05/09 07:02:12 fredb Exp $

#include "pngimage.hpp"

#include <png.h>
#include <stdio.h>

#include <string.h>

FGSD_PNGImage::FGSD_PNGImage( bool __reverted )
   :  _reverted( __reverted )
{
}

FGSD_PNGImage::~FGSD_PNGImage ()
{
}

bool FGSD_PNGImage::load (const char *__fileName)
{
   bool ret = false;
   FILE *infile = fopen( __fileName, "rb" );

   if ( infile != 0 )
      {
      char *header[8];
      fread( header, 1, 8, infile );
      if ( png_sig_cmp( (png_bytep)header, 0, 8) == 0 )
         {
         // allocate some structures
         png_structp png_ptr = png_create_read_struct( PNG_LIBPNG_VER_STRING, NULL, NULL, NULL );
         if ( png_ptr )
            {
            png_infop info_ptr  = png_create_info_struct( png_ptr );
            if ( info_ptr )
               {
               png_infop end_info  = png_create_info_struct( png_ptr );
               if ( end_info )
                  {
                  // initialize IO
                  png_init_io(png_ptr, infile);
                  png_set_sig_bytes( png_ptr, 8 );

                  png_read_info( png_ptr, info_ptr );

                  double gamma;
                  if ( png_get_gAMA(png_ptr, info_ptr, &gamma) ) {
                     png_set_gamma( png_ptr, 2.0, gamma );
                  } else {
                     png_set_gamma( png_ptr, 2.0, 0.45455 );
                  }

                  if ( png_get_color_type(png_ptr, info_ptr) == PNG_COLOR_TYPE_PALETTE )
                     png_set_expand( png_ptr );

                  png_read_update_info( png_ptr, info_ptr );

                  _width  = png_get_image_width (png_ptr, info_ptr);
                  _height = png_get_image_height(png_ptr, info_ptr);

                  // allocate image chunk
                  png_bytep *rows = new png_bytep[_height];
                  allocImage( _width, _height, 3 );
                  for ( unsigned int i = 0; i < _height; i++ ) {
                     if ( _reverted )
                        rows[_height - i - 1] = (png_bytep)(_buffer + i * (_width) * 3);
                     else
                        rows[i] = (png_bytep)(_buffer + i * (_width) * 3);
                  }

                  png_read_image(png_ptr, rows);

                  delete[] rows;

                  png_read_end( png_ptr, end_info );

                  png_destroy_read_struct( &png_ptr, &info_ptr, &end_info );
                  }
               }
            }
         }

      fclose(infile);

      ret = true;
      }

   return ret;
}