jpeg_reader.tpp

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/*
  CLAW - a C++ Library Absolutely Wonderful

  CLAW is a free library without any particular aim but being useful to 
  anyone.

  Copyright (C) 2005-2011 Julien Jorge

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library 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
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

  contact: julien.jorge@gamned.org
*/
#include <claw/jpeg_error_manager.hpp>
#include <claw/exception.hpp>

/*----------------------------------------------------------------------------*/
template<class Convert>
void claw::graphic::jpeg::reader::read_data
( jpeg_decompress_struct& cinfo, const Convert& pixel_convert )
{
  const unsigned int pixel_size = cinfo.output_components;
  JSAMPLE* buffer = new JSAMPLE[cinfo.output_width * pixel_size];

  error_manager jerr;
  jpeg_error_mgr* jerr_saved = cinfo.err;

  cinfo.err = jpeg_std_error(&jerr.pub);
  jerr.pub.error_exit = jpeg__error_manager__error_exit;

  if ( setjmp(jerr.setjmp_buffer) )
    {
      delete[] buffer;
      throw CLAW_EXCEPTION(jerr.error_string);
    }

  while (cinfo.output_scanline < cinfo.output_height)
    {
      jpeg_read_scanlines(&cinfo, &buffer, 1);

      scanline::iterator pixel = m_image[cinfo.output_scanline-1].begin();

      for ( unsigned int i=0; i!=pixel_size*m_image.width();
            i+=pixel_size, ++pixel )
        *pixel = pixel_convert( &buffer[i] );
    }

  delete[] buffer;
  cinfo.err = jerr_saved;
} // jpeg::reader::read_data()