/****************************************************************************
**
** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/
**
** This file is part of the Qt Graphical Effects module.
**
** $QT_BEGIN_LICENSE:BSD$
** You may use this file under the terms of the BSD license as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor
**     the names of its contributors may be used to endorse or promote
**     products derived from this software without specific prior written
**     permission.
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/

import QtQuick 2.0
import "private"

Item {
    id: rootItem
    property variant source
    property real hue: 0.0
    property real saturation: 1.0
    property real lightness: 0.0
    property bool cached: false

    SourceProxy {
        id: sourceProxy
        input: rootItem.source
    }

    ShaderEffectSource {
        id: cacheItem
        anchors.fill: parent
        visible: rootItem.cached
        smooth: true
        sourceItem: shaderItem
        live: true
        hideSource: visible
    }

    ShaderEffect {
        id: shaderItem
        property variant source: sourceProxy.output
        property real hue: rootItem.hue
        property real saturation: rootItem.saturation
        property real lightness: rootItem.lightness

        anchors.fill: parent

        fragmentShader: "
            varying mediump vec2 qt_TexCoord0;
            uniform highp float qt_Opacity;
            uniform lowp sampler2D source;
            uniform highp float hue;
            uniform highp float saturation;
            uniform highp float lightness;

            highp float RGBtoL(highp vec3 color) {
                highp float cmin = min(color.r, min(color.g, color.b));
                highp float cmax = max(color.r, max(color.g, color.b));
                highp float l = (cmin + cmax) / 2.0;
                return l;
            }

            highp float hueToIntensity(highp float v1, highp float v2, highp float h) {
                h = fract(h);
                if (h < 1.0 / 6.0)
                    return v1 + (v2 - v1) * 6.0 * h;
                else if (h < 1.0 / 2.0)
                    return v2;
                else if (h < 2.0 / 3.0)
                    return v1 + (v2 - v1) * 6.0 * (2.0 / 3.0 - h);

                return v1;
            }

            highp vec3 HSLtoRGB(highp vec3 color) {
                highp float h = color.x;
                highp float l = color.z;
                highp float s = color.y;

                if (s < 1.0 / 256.0)
                    return vec3(l, l, l);

                highp float v1;
                highp float v2;
                if (l < 0.5)
                    v2 = l * (1.0 + s);
                else
                    v2 = (l + s) - (s * l);

                v1 = 2.0 * l - v2;

                highp float d = 1.0 / 3.0;
                highp float r = hueToIntensity(v1, v2, h + d);
                highp float g = hueToIntensity(v1, v2, h);
                highp float b = hueToIntensity(v1, v2, h - d);
                return vec3(r, g, b);
            }

            void main() {
                lowp vec4 sample = texture2D(source, qt_TexCoord0);
                sample = vec4(sample.rgb / max(1.0/256.0, sample.a), sample.a);
                highp float light = RGBtoL(sample.rgb);
                highp float c = step(0.0, lightness);
                sample.rgb = HSLtoRGB(vec3(hue, saturation, mix(light, c, abs(lightness))));
                gl_FragColor = vec4(sample.rgb * sample.a, sample.a) * qt_Opacity;
            }
        "
    }
}