error_diffusion.h

// Aseprite Render Library
// Copyright (c) 2019 Igara Studio S.A
// Copyright (c) 2017 David Capello
//
// This file is released under the terms of the MIT license.
// Read LICENSE.txt for more information.

#ifndef RENDER_ERROR_DIFFUSION_H_INCLUDED
#define RENDER_ERROR_DIFFUSION_H_INCLUDED
#pragma once

#include "doc/image_ref.h"
#include "render/ordered_dither.h"

#include <vector>

namespace render {

  class ErrorDiffusionDither : public DitheringAlgorithmBase {
  public:
    ErrorDiffusionDither(int transparentIndex = -1);
    int dimensions() const override { return 2; }
    bool zigZag() const override { return true; }
    void start(
      const doc::Image* srcImage,
      doc::Image* dstImage,
      const double factor) override;
    void finish() override;
    doc::color_t ditherRgbToIndex2D(
      const int x, const int y,
      const doc::RgbMap* rgbmap,
      const doc::Palette* palette) override;
  private:
    int m_transparentIndex;
    const doc::Image* m_srcImage;
    int m_width, m_lastY;
    static const int kChannels = 4;
    std::vector<int> m_err[kChannels];
    int m_factor;
  };

} // namespace render

#endif