color_utils.cpp

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#include <cmath>
#include "color_utils.hpp"

namespace color_widgets {
namespace detail {

QColor color_from_lch(qreal hue, qreal chroma, qreal luma, qreal alpha )
{
    qreal h1 = hue*6;
    qreal x = chroma*(1-qAbs(std::fmod(h1,2)-1));
    QColor col;
    if ( h1 >= 0 && h1 < 1 )
        col = QColor::fromRgbF(chroma,x,0);
    else if ( h1 < 2 )
        col = QColor::fromRgbF(x,chroma,0);
    else if ( h1 < 3 )
        col = QColor::fromRgbF(0,chroma,x);
    else if ( h1 < 4 )
        col = QColor::fromRgbF(0,x,chroma);
    else if ( h1 < 5 )
        col = QColor::fromRgbF(x,0,chroma);
    else if ( h1 < 6 )
        col = QColor::fromRgbF(chroma,0,x);

    qreal m = luma - color_lumaF(col);

    return QColor::fromRgbF(
        qBound(0.0,col.redF()+m,1.0),
        qBound(0.0,col.greenF()+m,1.0),
        qBound(0.0,col.blueF()+m,1.0),
        alpha);
}

QColor color_from_hsl(qreal hue, qreal sat, qreal lig, qreal alpha )
{
    qreal chroma = (1 - qAbs(2*lig-1))*sat;
    qreal h1 = hue*6;
    qreal x = chroma*(1-qAbs(std::fmod(h1,2)-1));
    QColor col;
    if ( h1 >= 0 && h1 < 1 )
        col = QColor::fromRgbF(chroma,x,0);
    else if ( h1 < 2 )
        col = QColor::fromRgbF(x,chroma,0);
    else if ( h1 < 3 )
        col = QColor::fromRgbF(0,chroma,x);
    else if ( h1 < 4 )
        col = QColor::fromRgbF(0,x,chroma);
    else if ( h1 < 5 )
        col = QColor::fromRgbF(x,0,chroma);
    else if ( h1 < 6 )
        col = QColor::fromRgbF(chroma,0,x);

    qreal m = lig-chroma/2;

    return QColor::fromRgbF(
        qBound(0.0,col.redF()+m,1.0),
        qBound(0.0,col.greenF()+m,1.0),
        qBound(0.0,col.blueF()+m,1.0),
        alpha);
}

} // namespace detail
} // namespace color_widgets