// vim: set tabstop=4 shiftwidth=4 noexpandtab:
/*
Gwenview: an image viewer
Copyright 2008 Aurélien Gâteau <agateau@kde.org>

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.

*/
#ifndef RAMP_H
#define RAMP_H

namespace Gwenview {

/**
 * This class maps values on a linear ramp.
 * It's useful to do mappings like this:
 *
 * x | -oo       x1               x2     +oo
 * --+--------------------------------------
 * y |  y1       y1 (linear ramp) y2      y2
 *
 * Note that y1 can be greater than y2 if necessary
 */
class Ramp {
public:
	Ramp(qreal x1, qreal x2, qreal y1, qreal y2)
	: mX1(x1)
	, mX2(x2)
	, mY1(y1)
	, mY2(y2)
	{
		mK = (y2 - y1) / (x2 - x1);
	}

	qreal operator()(qreal x) const {
		if (x < mX1) {
			return mY1;
		}
		if (x > mX2) {
			return mY2;
		}
		return mY1 + (x - mX1) * mK;
	}

private:
	qreal mX1, mX2, mY1, mY2, mK;
};

} // namespace

#endif /* RAMP_H */
