186 lines
6 KiB
QML
186 lines
6 KiB
QML
/****************************************************************************
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**
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** Copyright (C) 2017 The Qt Company Ltd.
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** Contact: https://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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** $QT_BEGIN_LICENSE:LGPL$
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and The Qt Company. For licensing terms
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** and conditions see https://www.qt.io/terms-conditions. For further
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** information use the contact form at https://www.qt.io/contact-us.
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**
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** GNU Lesser General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU Lesser
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** General Public License version 3 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL3 included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU Lesser General Public License version 3 requirements
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** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
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**
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** GNU General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU
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** General Public License version 2.0 or (at your option) the GNU General
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** Public license version 3 or any later version approved by the KDE Free
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** Qt Foundation. The licenses are as published by the Free Software
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** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
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** included in the packaging of this file. Please review the following
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** information to ensure the GNU General Public License requirements will
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** be met: https://www.gnu.org/licenses/gpl-2.0.html and
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** https://www.gnu.org/licenses/gpl-3.0.html.
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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 2.12
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import QtGraphicalEffects.private 1.12
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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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\note This effect is available when running with OpenGL.
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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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interpolation: rootItem.smooth || (rootItem.layer.enabled && rootItem.layer.smooth)
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? SourceProxy.NearestInterpolation : SourceProxy.LinearInterpolation
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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: "qrc:/qt-project.org/imports/QtGraphicalEffects/shaders/gammaadjust.frag"
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}
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}
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