194 lines
6.3 KiB
QML
194 lines
6.3 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 GammaAdjust
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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 Alters the luminance of the source item.
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GammaAdjust is applied to each pixel according to the curve which is
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pre-defined as a power-law expression, where the property gamma is used as the
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reciprocal scaling exponent. Refer to the property documentation of \l{GammaAdjust::gamma}{gamma}
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for more details.
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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 GammaAdjust_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 GammaAdjust-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 for which the luminance is going to be
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adjusted.
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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 the change factor for how the luminance of each pixel
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is altered according to the equation:
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\code
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luminance = pow(original_luminance, 1.0 / gamma); // The luminance is assumed to be between 0.0 and 1.0
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\endcode
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Setting the gamma values under 1.0 makes the image darker, the values
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above 1.0 lighten it.
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The value ranges from 0.0 (darkest) to inf (lightest). By default, the
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property is set to \c 1.0 (no change).
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\table
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\header
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\li Output examples with different gamma values
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\li
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\li
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\row
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\li \image GammaAdjust_gamma1.png
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\li \image GammaAdjust_gamma2.png
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\li \image GammaAdjust_gamma3.png
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\row
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\li \b { gamma: 0.5 }
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\li \b { gamma: 1.0 }
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\li \b { gamma: 2.0 }
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\endtable
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\table
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\header
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\li Pixel luminance curves of the above images.
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\li
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\li
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\row
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\li \image GammaAdjust_gamma1_graph.png
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\li \image GammaAdjust_gamma2_graph.png
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\li \image GammaAdjust_gamma3_graph.png
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\row
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\li Red curve: default gamma (1.0)
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\li
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\li
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\row
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\li Yellow curve: effect applied
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\li
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\li
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\row
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\li X-axis: pixel original luminance
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\li
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\li
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\row
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\li Y-axis: pixel luminance with effect applied
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\li
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\li
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\endtable
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*/
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property real gamma: 1.0
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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 gamma: 1.0 / Math.max(rootItem.gamma, 0.0001)
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anchors.fill: parent
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fragmentShader: "
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varying highp 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 gamma;
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void main(void) {
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highp vec4 originalColor = texture2D(source, qt_TexCoord0.st);
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originalColor.rgb = originalColor.rgb / max(1.0/256.0, originalColor.a);
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highp vec3 adjustedColor = pow(originalColor.rgb, vec3(gamma));
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gl_FragColor = vec4(adjustedColor * originalColor.a, originalColor.a) * qt_Opacity;
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}
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"
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}
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}
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