ScaleEngine.cpp

/***************************************************************************
   	File                 : ScaleEngine.cpp
    Project              : QtiPlot
    --------------------------------------------------------------------
    Copyright            : (C) 2007 by Ion Vasilief
    Email (use @ for *)  : ion_vasilief*yahoo.fr
    Description          : Extensions to QwtScaleEngine and QwtScaleTransformation

 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *  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                                           *
 *                                                                         *
 ***************************************************************************/
#include "qwt_compat.h"
#include "ScaleEngine.h"

QwtScaleTransformation* ScaleEngine::transformation() const
{
	return new ScaleTransformation(this);
}

double ScaleTransformation::invXForm(double p, double p1, double p2, double s1, double s2) const
{
    if (!d_engine->hasBreak()){
        QwtScaleTransformation *tr = new QwtScaleTransformation (d_engine->type());
        double res = tr->invXForm(p, p1, p2, s1, s2);
        delete tr;
        return res;
    }
	
    const int d_break_space = d_engine->breakWidth();
	const double lb = d_engine->axisBreakLeft();
    const double rb = d_engine->axisBreakRight();
	const double pm = p1 + (p2 - p1)*(double)d_engine->breakPosition()/100.0;
	double pml, pmr;
	if (p2 > p1){
		pml = pm - d_break_space;
		pmr = pm + d_break_space;
	} else {
		pml = pm + d_break_space;
		pmr = pm - d_break_space;
	}

	if (p > pml && p < pmr)
		return pm;
	
	bool invertedScale = d_engine->testAttribute(QwtScaleEngine::Inverted);
	QwtScaleTransformation::Type d_type = d_engine->type();

	if (invertedScale){
		if ((p2 > p1 && p <= pml) || (p2 < p1 && p >= pml)){
			if (d_engine->log10ScaleAfterBreak())
				return s1*exp((p - p1)/(pml - p1)*log(rb/s1));
            else 
				return s1 + (rb - s1)/(pml - p1)*(p - p1);