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/****************************************************************************
**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** 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 Digia Plc 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"
/*!
\qmltype Desaturate
\inqmlmodule QtGraphicalEffects 1.0
\since QtGraphicalEffects 1.0
\inherits QtQuick2::Item
\ingroup qtgraphicaleffects-color
\brief Reduces the saturation of the colors.
Desaturated pixel values are calculated as averages of the original RGB
component values of the source item.
\table
\header
\li Source
\li Effect applied
\row
\li \image Original_bug.png
\li \image Desaturate_bug.png
\endtable
\section1 Example
The following example shows how to apply the effect.
\snippet Desaturate-example.qml example
*/
Item {
id: rootItem
/*!
This property defines the source item that provides the source pixels to
the effect.
\note It is not supported to let the effect include itself, for
instance by setting source to the effect's parent.
*/
property variant source
/*!
This property defines how much the source colors are desaturated.
The value ranges from 0.0 (no change) to 1.0 (desaturated). By default,
the property is set to \c 0.0 (no chnage).
\table
\header
\li Output examples with different desaturation values
\li
\li
\row
\li \image Desaturate_desaturation1.png
\li \image Desaturate_desaturation2.png
\li \image Desaturate_desaturation3.png
\row
\li \b { desaturation: 0.0 }
\li \b { desaturation: 0.5 }
\li \b { desaturation: 1.0 }
\endtable
*/
property real desaturation: 0.0
/*!
This property allows the effect output pixels to be cached in order to
improve the rendering performance.
Every time the source or effect properties are changed, the pixels in
the cache must be updated. Memory consumption is increased, because an
extra buffer of memory is required for storing the effect output.
It is recommended to disable the cache when the source or the effect
properties are animated.
By default, the property is set to \c false.
*/
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 desaturation: rootItem.desaturation
anchors.fill: parent
fragmentShader: "
varying highp vec2 qt_TexCoord0;
uniform highp float qt_Opacity;
uniform lowp sampler2D source;
uniform highp float desaturation;
void main(void) {
lowp vec4 textureColor = texture2D(source, qt_TexCoord0.st);
lowp float grayColor = (textureColor.r + textureColor.g + textureColor.b) / 3.0;
gl_FragColor = mix(textureColor, vec4(vec3(grayColor), textureColor.a), desaturation) * qt_Opacity;
}
"
}
}
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