/****************************************************************************
**
** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
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** This file is part of the Qt Mobility Components.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
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** GNU Lesser General Public License Usage
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** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
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** rights.  These rights are described in the Digia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
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****************************************************************************/

import QtQuick 2.0

Effect {
    parameters: ListModel {
        ListElement {
            name: "hue"
            value: 0.5
        }
        ListElement {
            name: "width"
            value: 0.5
        }
    }

    // Transform slider values, and bind result to shader uniforms
    property real targetHue: parameters.get(0).value * 360
    property real windowWidth: parameters.get(1).value * 60

    fragmentShaderSrc: "uniform float targetHue;
                        uniform float windowWidth;
                        uniform float dividerValue;

                        uniform sampler2D source;
                        uniform lowp float qt_Opacity;
                        varying vec2 qt_TexCoord0;

                        void rgb2hsl(vec3 rgb, out float h, out float s, float l)
                        {
                            float maxval = max(rgb.r, max(rgb.g, rgb.b));
                            float minval = min(rgb.r, min(rgb.g, rgb.b));
                            float delta = maxval - minval;
                            l = (minval + maxval) / 2.0;
                            s = 0.0;
                            if (l > 0.0 && l < 1.0)
                                s = delta / (l < 0.5 ? 2.0 * l : 2.0 - 2.0 * l);
                            h = 0.0;
                            if (delta > 0.0)
                            {
                                if (rgb.r == maxval && rgb.g != maxval)
                                    h += (rgb.g - rgb.b ) / delta;
                                if (rgb.g == maxval && rgb.b != maxval)
                                    h += 2.0  + (rgb.b - rgb.r) / delta;
                                if (rgb.b == maxval && rgb.r != maxval)
                                    h += 4.0 + (rgb.r - rgb.g) / delta;
                                h *= 60.0;
                            }
                        }

                        void main()
                        {
                            vec2 uv = qt_TexCoord0.xy;
                            vec3 col = texture2D(source, uv).rgb;
                            float h, s, l;
                            rgb2hsl(col, h, s, l);
                            float h2 = (h > targetHue) ? h - 360.0 : h + 360.0;
                            float y = 0.3 * col.r + 0.59 * col.g + 0.11 * col.b;
                            vec3 result;
                            if (uv.x > dividerValue || (abs(h - targetHue) < windowWidth) || (abs(h2 - targetHue) < windowWidth))
                                result = col;
                            else
                                result = vec3(y, y, y);
                            gl_FragColor = qt_Opacity * vec4(result, 1.0);
                        }"
}