/*
 * $Revision: 2523 $
 *
 * last checkin:
 *   $Author: gutwenger $
 *   $Date: 2012-07-02 20:59:27 +0200 (Mon, 02 Jul 2012) $
 ***************************************************************/

/** \file
 * \brief Declaration of class FruchtermanReingold (computation of forces).
 *
 * \author Stefan Hachul
 *
 * \par License:
 * This file is part of the Open Graph Drawing Framework (OGDF).
 *
 * \par
 * Copyright (C)<br>
 * See README.txt in the root directory of the OGDF installation for details.
 *
 * \par
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * Version 2 or 3 as published by the Free Software Foundation;
 * see the file LICENSE.txt included in the packaging of this file
 * for details.
 *
 * \par
 * 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.
 *
 * \par
 * 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.
 *
 * \see  http://www.gnu.org/copyleft/gpl.html
 ***************************************************************/


#ifdef _MSC_VER
#pragma once
#endif

#ifndef OGDF_FRUCHTERMAN_REINGOLD_H
#define OGDF_FRUCHTERMAN_REINGOLD_H

#include <ogdf/basic/Graph.h>
#include <ogdf/basic/geometry.h>
#include <ogdf/basic/NodeArray.h>
#include <ogdf/internal/energybased/NodeAttributes.h>
#include <ogdf/internal/energybased/EdgeAttributes.h>

namespace ogdf {

class OGDF_EXPORT FruchtermanReingold
{
public:
	FruchtermanReingold();          //constructor
	~FruchtermanReingold() { }      //destructor

	//Calculate exact rep. forces for each node.
	void calculate_exact_repulsive_forces(
		const Graph &G,
		NodeArray<NodeAttributes>& A,
		NodeArray<DPoint>& F_rep);

	//Grid approximation of rep.forces for each node.
	void calculate_approx_repulsive_forces(
		const Graph &G,
		NodeArray<NodeAttributes>& A,
		NodeArray<DPoint>& F_rep);

	//Make all initialisations that are needed for FruchtermanReingold.
	void make_initialisations (
		double boxlength,
		DPoint down_left_corner,
		int grid_quotient);

	//Import updated information of the drawing area.
	void update_boxlength_and_cornercoordinate(double b_l, DPoint d_l_c) {
		boxlength = b_l; down_left_corner = d_l_c;
	}

private:
	int _grid_quotient;//for coarsening the FrRe-grid
	int max_gridindex; //maximum index of a grid row/column
	double boxlength;  //length of drawing box
	DPoint down_left_corner;//down left corner of drawing box

	//Returns the repulsing force_function_value of scalar d.
	double f_rep_scalar (double d);

	//The number k of rows and colums of the grid is sqrt(|V|) / frGridQuotient()
	//(Note that in [FrRe] frGridQuotient() is 2.)
	void grid_quotient(int p) { _grid_quotient = ((0<=p) ? p : 2);}
	int grid_quotient() const {return _grid_quotient;}
};

}//namespace ogdf
#endif

