latte-dock/app/commontools.cpp

/*
 * Copyright 2018  Michail Vourlakos <mvourlakos@gmail.com>
 *
 * This file is part of Latte-Dock
 *
 * Latte-Dock 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.
 *
 * Latte-Dock 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, see <http://www.gnu.org/licenses/>.
 *
 */

#include "commontools.h"

#include <QtMath>

namespace Latte {

float colorLumina(QRgb rgb)
{
    float r = (float)(qRed(rgb)) / 255;
    float g = (float)(qGreen(rgb)) / 255;
    float b = (float)(qBlue(rgb)) / 255;

    return colorLumina(r, g, b);
}

float colorLumina(QColor color)
{
    return colorLumina(color.redF(), color.greenF(), color.blueF());
}

float colorLumina(float r, float g, float b)
{
    // formula for luminance according to:
    // https://www.w3.org/TR/2008/REC-WCAG20-20081211/#relativeluminancedef

    float rS = (r <= 0.03928 ? r / 12.92 : qPow(((r + 0.055) / 1.055), 2.4));
    float gS = (g <= 0.03928 ? g / 12.92 : qPow(((g + 0.055) / 1.055), 2.4));
    float bS = (b <= 0.03928 ? b / 12.92 : qPow(((b + 0.055) / 1.055), 2.4));

    float luminosity = 0.2126 * rS + 0.7152 * gS + 0.0722 * bS;

    return luminosity;
}

}