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VG91.cxx

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/*
 * @(#)src/VG91.cxx  1.0  2002-09-07 09:52
 *
 * Copyright (C)  2002  Daniel Léonard
 *
 * 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#include <utility>
#include "Image.h"
#include "SFCPath.h"
#include "SFCPathFactory.h"
#include "VG91.h"
#include "VGSpec.h"

namespace halftoner
{

//---------------------------
// Constructor
//---------------------------

   VG91::VG91() throw()
   {
   // nothing
   }


//---------------------------
// Destructor
//---------------------------

   VG91::~VG91()
   {
   // nothing
   }


//---------------------------
// Implemented method from Halftoner
//---------------------------

   Image* VG91::halftone(const Image& source, const HalftonerSpec* spec) throw (std::invalid_argument)
   {
   // dimensions
      const int width = source.getWidth();
      const int height = source.getHeight();
   // square check
      if (width != height)
      {
         string s("image is not square");
         throw std::invalid_argument(s);
      }


   // getting the curve (can throw std::invalid_argument)
      const VGSpec* vgspec = dynamic_cast<const VGSpec*>(spec);
      int cluster = vgspec->getClusterSize();
      const SFCPathFactory::SizeMnemonic& mnemonic = vgspec->getMnemonic();
      SFCPath* curve = SFCPathFactory::getInstance(mnemonic);

   // destination image
      Image* out = new Image(width, height);

   // needed variables
      int accumulator = 0;
      int len = width * height;
      std::pair<int, int> p;
   // here we go
      for (int i = 0; i < len; i += cluster)
      {
      // accumulator
         for (int n = 0; n < cluster; n++)
         {
            if (i + n < len)
            {
               p = (*curve)[i + n];
               accumulator += source.getColorAt(p.first, p.second);
            }
         }
      // distributing
         for (int n = 0; n < cluster; n++)
         {
            if (i + n < len)
            {
               p = (*curve)[i + n];
               if (accumulator >= 255)
               {
                  accumulator -= 255;
                  out->setColorAt(p.first, p.second, 1);
               }
               else
               {
                  out->setColorAt(p.first, p.second, 0);
               }
            }
         }
      }

      delete curve;

      return out;
   }

}

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