/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

#ifndef __GAUSSIANFILTER_H__
#define __GAUSSIANFILTER_H__

/** \file blender/freestyle/intern/image/GaussianFilter.h
 *  \ingroup freestyle
 *  \brief Class to perform gaussian filtering operations on an image
 *  \author Stephane Grabli
 *  \date 20/05/2003
 */

#include <cstdlib> // for abs
#include <string.h> // for memcpy

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

extern "C" {
#include "BLI_math.h"
}

#ifdef WITH_CXX_GUARDEDALLOC
#include "MEM_guardedalloc.h"
#endif

namespace Freestyle {

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;
	// the real mask size (must be odd)(the size of the mask we store is ((_maskSize+1)/2)*((_maskSize+1)/2))
	int _maskSize;
	int _storedMaskSize; // (_maskSize+1)/2)

public:
	GaussianFilter(float iSigma = 1.0f);
	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 following 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);
#if 0
	void SetMaskSize(int size)
	{
		_maskSize = size;
		_storedMaskSize = (_maskSize + 1) >> 1;
	}
#endif

protected:
	void computeMask();

#ifdef WITH_CXX_GUARDEDALLOC
	MEM_CXX_CLASS_ALLOC_FUNCS("Freestyle:GaussianFilter")
#endif
};

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

template<class Map>
float GaussianFilter::getSmoothedPixel(Map *map, int x, int y)
{
	float sum = 0.0f;
	float L = 0.0f;
	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;
}

} /* namespace Freestyle */

#endif // __GAUSSIANFILTER_H__