//
//  Filename         : Image.h
//  Author(s)        : Stephane Grabli
//  Purpose          : Class to perform gaussian filtering operations on an image
//  Date of creation : 20/05/2003
//
///////////////////////////////////////////////////////////////////////////////


//
//  Copyright (C) : Please refer to the COPYRIGHT file distributed 
//   with this source distribution. 
//
//  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  GAUSSIANFILTER_H
# define GAUSSIANFILTER_H

#include "../system/FreestyleConfig.h"

class LIB_IMAGE_EXPORT GaussianFilter{
protected:
  /* the mask is a symetrical 2d array (with respect 
  to the middle point). 
  Thus, M(i,j) = M(-i,j) = M(i,-j) = M(-i,-j).
  For this reason, to represent a NxN array (N odd), we only store
  a ((N+1)/2)x((N+1)/2) array.
  */
  float _sigma;
  float *_mask;
  int _bound;
  int _maskSize; // the real mask size (must be odd)(the size of the mask we store is ((_maskSize+1)/2)*((_maskSize+1)/2))
  int _storedMaskSize; //(_maskSize+1)/2)
 
public:
  GaussianFilter(float iSigma = 1.f) ;
  GaussianFilter(const GaussianFilter&) ;
  GaussianFilter& operator= (const GaussianFilter&) ;
  virtual ~GaussianFilter() ;

  /*! Returns the value for pixel x,y of image "map" after a gaussian blur, 
   *  made using the sigma value.
   *  The sigma value determines the mask size (~ 2 x sigma).
   *  \param map
   *    The image we wish to work on. The Map template must implement the 
   *    foloowing methods: 
   *    - float pixel(unsigned int x,unsigned int y) const;
   *    - unsigned width() const;
   *    - unsigned height() const;
   *  \param x
   *    The abscissa of the pixel where we want to evaluate the gaussian blur.
   *  \param y
   *    The ordinate of the pixel where we want to evaluate the gaussian blur.
   *  \param sigma
   *    The sigma value of the gaussian function.
   */
  template<class Map>
  float getSmoothedPixel(Map * map, int x, int y) ;
  
  /*! Compute the mask size and returns the REAL mask size ((2*_maskSize)-1)
   *  This method is provided for convenience.
   */
  static int computeMaskSize(float sigma) ;

  /*! accessors */
  inline float sigma() const {return _sigma;}
  inline int maskSize() const {return _maskSize;}
  inline int getBound() {return _bound;}

  /*! modifiers */
  void setSigma(float sigma) ;
  // void SetMaskSize(int size) {_maskSize = size;_storedMaskSize=(_maskSize+1)>>1;}
  
    
protected:
  void computeMask();
};

/*
  
  #############################################
  #############################################
  #############################################
  ######                                 ######
  ######   I M P L E M E N T A T I O N   ######
  ######                                 ######
  #############################################
  #############################################
  #############################################
  
*/


#include <math.h>

#ifdef __MACH__
#define sqrtf(x) (sqrt(x))
#endif

template<class Map>
float GaussianFilter::getSmoothedPixel(Map * map, int x, int y)
{
  float sum = 0.f;  
  float L=0.f;
  int w = (int)map->width(); //soc
  int h = (int)map->height(); //soc

  // Current pixel is x,y
  // Sum surrounding pixels L value:
  for(int i=-_bound; i<=_bound; ++i)
  {
    if((y+i < 0) || (y+i >= h))
      continue;
    for(int j=-_bound; j<=_bound; ++j)
    {
      if((x+j < 0) || (x+j >= w))
        continue;
      
      float tmpL = map->pixel(x+j,y+i);
      float m = _mask[abs(i)*_storedMaskSize+abs(j)];
      L += m*tmpL;
      sum += m;
    }
  }
  //L /= sum;
  return L;
}


#endif // GAUSSIANFILTER