qskinny/src/controls/QskRgbValue.cpp

/******************************************************************************
 * QSkinny - Copyright (C) 2016 Uwe Rathmann
 * This file may be used under the terms of the QSkinny License, Version 1.0
 *****************************************************************************/

#include "QskRgbValue.h"

namespace
{
    inline int value( int from, int to, qreal ratio )
    {
        return int( from + ( to - from ) * ratio );
    }
}

static inline QColor qskInterpolatedColor(
    const QColor& c1, const QColor& c2, qreal ratio )
{
    switch( c1.spec() )
    {
        case QColor::Rgb:
        {
            const int r = value( c1.red(), c2.red(), ratio );
            const int g = value( c1.green(), c2.green(), ratio );
            const int b = value( c1.blue(), c2.blue(), ratio );
            const int a = value( c1.alpha(), c2.alpha(), ratio );

            return QColor::fromRgb( r, g, b, a );
        }   
        case QColor::Hsv:
        {
            const int h = value( c1.hue(), c2.hue(), ratio );
            const int s = value( c1.saturation(), c2.saturation(), ratio );
            const int v = value( c1.value(), c2.value(), ratio );
            const int a = value( c1.alpha(), c2.alpha(), ratio );
            
            return QColor::fromHsv( h, s, v, a );
        }   
        case QColor::Cmyk:
        {
            const int c = value( c1.cyan(), c2.cyan(), ratio );
            const int m = value( c1.magenta(), c2.magenta(), ratio ); 
            const int y = value( c1.yellow(), c2.yellow(), ratio );
            const int k = value( c1.black(), c2.black(), ratio );
            const int a = value( c1.alpha(), c2.alpha(), ratio );

            return QColor::fromCmykF( c, m, y, k, a );
        }   
        case QColor::Hsl:
        {
            const int h = value( c1.hue(), c2.hue(), ratio );
            const int s = value( c1.saturation(), c2.saturation(), ratio );
            const int l = value( c1.lightness(), c2.lightness(), ratio );
            const int a = value( c1.alpha(), c2.alpha(), ratio );
 
            return QColor::fromHsl( h, s, l, a );
        }   
        case QColor::Invalid:
            break;
    }   

    return c2;
}

QRgb QskRgbValue::interpolated( QRgb rgb1, QRgb rgb2, qreal ratio )
{
    // interpolating in HSV usually provides better results !!

    if ( rgb1 == rgb2 )
        return rgb1;

    const int r = value( qRed( rgb1 ), qRed( rgb2 ), ratio );
    const int g = value( qGreen( rgb1 ), qGreen( rgb2 ), ratio );
    const int b = value( qBlue( rgb1 ), qBlue( rgb2 ), ratio );
    const int a = value( qAlpha( rgb1 ), qAlpha( rgb2 ), ratio );

    return qRgba( r, g, b, a );
}

QColor QskRgbValue::interpolated( const QColor& c1, const QColor& c2, qreal ratio )
{
    if ( c1 != c2 && c1.isValid() && c2.isValid() )
    {
        if ( c1.spec() == c2.spec() )
            return qskInterpolatedColor( c1, c2, ratio );
        else
            return qskInterpolatedColor( c1.convertTo( c2.spec() ), c2, ratio );
    }

    return c2;
}