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ErrorDiffusionHalftoner.h

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/*
 * @(#)include/ErrorDiffusionHalftoner.h  1.0  2002-08-27 12:27
 *
 * 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.
 */

#ifndef _ERROR_DIFFUSION_HALFTONER_H_
#define _ERROR_DIFFUSION_HALFTONER_H_

#include "Halftoner.h"

namespace halftoner
{
   class ErrorDiffusionSpec;
   class Image;

   class ErrorDiffusionHalftoner : public Halftoner
   {

      public:
         class PathStrategy
         {
            protected:
               PathStrategy() throw();

            public:
               virtual ~PathStrategy() throw();


               virtual Image* operator()(ErrorDiffusionHalftoner& halftoner, const Image& source, int threshold) throw() = 0;
         };

      private:
         class ScanlinePathStrategy : public ErrorDiffusionHalftoner::PathStrategy
         {
            public:
               Image* operator()(ErrorDiffusionHalftoner& halftoner, const Image& source, int threshold) throw();
         };
         friend class ErrorDiffusionHalftoner::ScanlinePathStrategy;

         class SerpentinePathStrategy : public ErrorDiffusionHalftoner::PathStrategy
         {
            public:
               Image* operator()(ErrorDiffusionHalftoner& halftoner, const Image& source, int threshold) throw();
         };
         friend class ErrorDiffusionHalftoner::SerpentinePathStrategy;


         static ErrorDiffusionHalftoner::ScanlinePathStrategy scan_line_strategy;
         static ErrorDiffusionHalftoner::SerpentinePathStrategy serpentine_strategy;

      public:
         static ErrorDiffusionHalftoner::PathStrategy& SCANLINE;
         static ErrorDiffusionHalftoner::PathStrategy& SERPENTINE;

      protected:
         ErrorDiffusionHalftoner() throw();

      public:
         virtual ~ErrorDiffusionHalftoner() throw();


         Image* halftone(const Image& source, const HalftonerSpec* spec) throw (std::invalid_argument);

      protected:

         virtual int halftoneToRight(float* source, int i, int j, int offset, int width, int height, int threshold) throw() = 0;

         virtual int halftoneToLeft(float* source, int i, int j, int offset, int width, int height, int threshold) throw() = 0;

      private:

         Image* scanline(const Image& source, int threshold);

         Image* serpentine(const Image& source, int threshold);
   };

}

#endif   /* define _ERROR_DIFFUSION_HALFTONER_H_ */

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