/*
 * KDE. Krita Project.
 *
 * Copyright (c) 2020 Deif Lou <ginoba@gmail.com>
 *
 * 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 "KisScreentoneBrightnessContrastFunctions.h"

namespace KisScreentoneBrightnessContrastFunctions {

BrightnessContrast::BrightnessContrast(qreal brightness, qreal contrast)
{
    if (contrast > 0.0) {
        if (qFuzzyCompare(contrast, 1.0)) {
            m_m = 10000.0;
        } else {
            m_m = 1.0 / (1.0 - contrast);
        }
        m_b = -m_m * (contrast / 2.0);
    } else {
        m_m = 1.0 + contrast;
        m_b = -contrast / 2.0;
    }
    m_b += (1.0 - m_b) * brightness;
}

qreal BrightnessContrast::operator()(qreal x) const
{
    return m_m * x + m_b;
}

}
