208 lines
6.9 KiB
QML
208 lines
6.9 KiB
QML
/****************************************************************************
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**
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** Copyright (C) 2015 The Qt Company Ltd.
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** Contact: http://www.qt.io/licensing/
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**
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** This file is part of the Qt Graphical Effects module.
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**
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** $QT_BEGIN_LICENSE:BSD$
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** You may use this file under the terms of the BSD license as follows:
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**
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** "Redistribution and use in source and binary forms, with or without
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** modification, are permitted provided that the following conditions are
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** met:
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** * Redistributions of source code must retain the above copyright
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** notice, this list of conditions and the following disclaimer.
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** * Redistributions in binary form must reproduce the above copyright
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** notice, this list of conditions and the following disclaimer in
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** the documentation and/or other materials provided with the
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** distribution.
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** * Neither the name of The Qt Company Ltd nor the names of its
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** contributors may be used to endorse or promote products derived
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** from this software without specific prior written permission.
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**
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**
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** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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import QtQuick 2.0
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import QtGraphicalEffects.private 1.0
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/*!
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\qmltype BrightnessContrast
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\inqmlmodule QtGraphicalEffects
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\since QtGraphicalEffects 1.0
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\inherits QtQuick2::Item
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\ingroup qtgraphicaleffects-color
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\brief Adjusts brightness and contrast.
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This effect adjusts the source item colors.
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Brightness adjustment changes the perceived luminance of the source item.
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Contrast adjustment increases or decreases the color
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and brightness variations.
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\table
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\header
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\li Source
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\li Effect applied
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\row
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\li \image Original_bug.png
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\li \image BrightnessContrast_bug.png
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\endtable
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\section1 Example
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The following example shows how to apply the effect.
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\snippet BrightnessContrast-example.qml example
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*/
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Item {
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id: rootItem
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/*!
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This property defines the source item that provides the source pixels
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for the effect.
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\note It is not supported to let the effect include itself, for
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instance by setting source to the effect's parent.
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*/
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property variant source
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/*!
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This property defines how much the source brightness is increased or
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decreased.
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The value ranges from -1.0 to 1.0. By default, the property is set to \c
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0.0 (no change).
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\table
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\header
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\li Output examples with different brightness values
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\li
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\li
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\row
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\li \image BrightnessContrast_brightness1.png
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\li \image BrightnessContrast_brightness2.png
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\li \image BrightnessContrast_brightness3.png
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\row
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\li \b { brightness: -0.25 }
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\li \b { brightness: 0 }
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\li \b { brightness: 0.5 }
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\row
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\li \l contrast: 0
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\li \l contrast: 0
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\li \l contrast: 0
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\endtable
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*/
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property real brightness: 0.0
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/*!
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This property defines how much the source contrast is increased or
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decreased. The decrease of the contrast is linear, but the increase is
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applied with a non-linear curve to allow very high contrast adjustment at
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the high end of the value range.
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\table
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\header
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\li Contrast adjustment curve
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\row
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\li \image BrightnessContrast_contrast_graph.png
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\endtable
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The value ranges from -1.0 to 1.0. By default, the property is set to \c 0.0 (no change).
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\table
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\header
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\li Output examples with different contrast values
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\li
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\li
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\row
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\li \image BrightnessContrast_contrast1.png
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\li \image BrightnessContrast_contrast2.png
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\li \image BrightnessContrast_contrast3.png
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\row
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\li \b { contrast: -0.5 }
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\li \b { contrast: 0 }
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\li \b { contrast: 0.5 }
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\row
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\li \l brightness: 0
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\li \l brightness: 0
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\li \l brightness: 0
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\endtable
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*/
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property real contrast: 0.0
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/*!
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This property allows the effect output pixels to be cached in order to
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improve the rendering performance.
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Every time the source or effect properties are changed, the pixels in
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the cache must be updated. Memory consumption is increased, because an
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extra buffer of memory is required for storing the effect output.
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It is recommended to disable the cache when the source or the effect
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properties are animated.
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By default, the property is set to \c false.
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*/
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property bool cached: false
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SourceProxy {
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id: sourceProxy
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input: rootItem.source
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}
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ShaderEffectSource {
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id: cacheItem
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anchors.fill: parent
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visible: rootItem.cached
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smooth: true
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sourceItem: shaderItem
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live: true
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hideSource: visible
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}
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ShaderEffect {
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id: shaderItem
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property variant source: sourceProxy.output
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property real brightness: rootItem.brightness
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property real contrast: rootItem.contrast
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anchors.fill: parent
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blending: !rootItem.cached
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fragmentShader: "
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varying mediump vec2 qt_TexCoord0;
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uniform highp float qt_Opacity;
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uniform lowp sampler2D source;
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uniform highp float brightness;
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uniform highp float contrast;
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void main() {
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highp vec4 pixelColor = texture2D(source, qt_TexCoord0);
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pixelColor.rgb /= max(1.0/256.0, pixelColor.a);
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highp float c = 1.0 + contrast;
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highp float contrastGainFactor = 1.0 + c * c * c * c * step(0.0, contrast);
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pixelColor.rgb = ((pixelColor.rgb - 0.5) * (contrastGainFactor * contrast + 1.0)) + 0.5;
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pixelColor.rgb = mix(pixelColor.rgb, vec3(step(0.0, brightness)), abs(brightness));
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gl_FragColor = vec4(pixelColor.rgb * pixelColor.a, pixelColor.a) * qt_Opacity;
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}
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"
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}
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}
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