/* blend.cpp
 * Copyright (C) 2006 Jean-Sebastien Senecal (js@drone.ws)
 * This file is a Frei0r plugin.
 * The code is a modified version of code from the Gimp.
 * 
 * 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.
 */

#include "frei0r.hpp"
#include "frei0r_math.h"

#define NBYTES 4
#define ALPHA 3

class blend : public frei0r::mixer2
{
public:
  blend(unsigned int width, unsigned int height)
  {
  	register_param(blend_factor,"blend","blend factor");
  }

  /**
   *
   * Perform a blend operation between sources in1 and in2, using
   * the generalised algorithm: D = A * (255 - β) + B * β
   *
   * The result is left in out
   **/
  void update()
  {
    const uint8_t *src1 = reinterpret_cast<const uint8_t*>(in1);
    const uint8_t *src2 = reinterpret_cast<const uint8_t*>(in2);
    uint8_t *dst = reinterpret_cast<uint8_t*>(out);
    const uint8_t bf = (const uint8_t) (255 * blend_factor);
    const uint8_t one_minus_bf = (255 - bf);
    uint32_t w = size;
    uint32_t b;
  
    while (w--)
      {
        for (b = 0; b < NBYTES; b++)
          dst[b] = (src1[b] * one_minus_bf + src2[b] * bf) / 255;
  
        src1 += NBYTES;
        src2 += NBYTES;
        dst += NBYTES;
      }
  }
  
private:
  double blend_factor;
    
};


frei0r::construct<blend> plugin("blend",
                                "Perform a blend operation between two sources",
                                "Jean-Sebastien Senecal",
                                0,1,
                                F0R_COLOR_MODEL_RGBA8888);