/****************************************************************************
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** Copyright (C) 2014 Gunnar Sletta <gunnar@sletta.org>
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** This file is part of the documentation of the Qt Toolkit.
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import QtQuick 2.0

Item {
    id: root
    width: 480
    height: 320

    // The checkers background
    ShaderEffect {
        id: tileBackground
        anchors.fill: parent

        property real tileSize: 20
        property color color1: Qt.hsla(0, 0, 0.1);
        property color color2: Qt.hsla(0, 0, 0.2);

        property size pixelSize: Qt.size(width / tileSize, height / tileSize);

        fragmentShader:
            "
            uniform lowp vec4 color1;
            uniform lowp vec4 color2;
            uniform highp vec2 pixelSize;
            varying highp vec2 qt_TexCoord0;
            void main() {
                highp vec2 tc = sign(sin(3.14152 * qt_TexCoord0 * pixelSize));
                if (tc.x != tc.y)
                    gl_FragColor = color1;
                else
                    gl_FragColor = color2;
            }
            "
    }

//! [1]
    Rectangle {
        id: gradientRect;
        width: 10
        height: 10
        gradient: Gradient {
            GradientStop { position: 0; color: "white" }
            GradientStop { position: 1; color: "steelblue" }
        }
        visible: false; // should not be visible on screen.
        layer.enabled: true;
        layer.smooth: true
    }

    Text {
        id: textItem
        font.pixelSize: 48
        text: "Gradient Text"
        anchors.centerIn: parent
        layer.enabled: true
        // This item should be used as the 'mask'
        layer.samplerName: "maskSource"
        layer.effect: ShaderEffect {
            property var colorSource: gradientRect;
            fragmentShader: "
                uniform lowp sampler2D colorSource;
                uniform lowp sampler2D maskSource;
                uniform lowp float qt_Opacity;
                varying highp vec2 qt_TexCoord0;
                void main() {
                    gl_FragColor =
                        texture2D(colorSource, qt_TexCoord0)
                        * texture2D(maskSource, qt_TexCoord0).a
                        * qt_Opacity;
                }
            "
        }
    }
//! [1]
}
