1/**************************************************************************** 2** 3** Copyright (C) 2017 The Qt Company Ltd. 4** Contact: https://www.qt.io/licensing/ 5** 6** This file is part of the Qt Graphical Effects module. 7** 8** $QT_BEGIN_LICENSE:LGPL$ 9** Commercial License Usage 10** Licensees holding valid commercial Qt licenses may use this file in 11** accordance with the commercial license agreement provided with the 12** Software or, alternatively, in accordance with the terms contained in 13** a written agreement between you and The Qt Company. For licensing terms 14** and conditions see https://www.qt.io/terms-conditions. For further 15** information use the contact form at https://www.qt.io/contact-us. 16** 17** GNU Lesser General Public License Usage 18** Alternatively, this file may be used under the terms of the GNU Lesser 19** General Public License version 3 as published by the Free Software 20** Foundation and appearing in the file LICENSE.LGPL3 included in the 21** packaging of this file. Please review the following information to 22** ensure the GNU Lesser General Public License version 3 requirements 23** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. 24** 25** GNU General Public License Usage 26** Alternatively, this file may be used under the terms of the GNU 27** General Public License version 2.0 or (at your option) the GNU General 28** Public license version 3 or any later version approved by the KDE Free 29** Qt Foundation. The licenses are as published by the Free Software 30** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 31** included in the packaging of this file. Please review the following 32** information to ensure the GNU General Public License requirements will 33** be met: https://www.gnu.org/licenses/gpl-2.0.html and 34** https://www.gnu.org/licenses/gpl-3.0.html. 35** 36** $QT_END_LICENSE$ 37** 38****************************************************************************/ 39 40import QtQuick 2.12 41import QtGraphicalEffects.private 1.12 42 43/*! 44 \qmltype GammaAdjust 45 \inqmlmodule QtGraphicalEffects 46 \since QtGraphicalEffects 1.0 47 \inherits QtQuick2::Item 48 \ingroup qtgraphicaleffects-color 49 \brief Alters the luminance of the source item. 50 51 GammaAdjust is applied to each pixel according to the curve which is 52 pre-defined as a power-law expression, where the property gamma is used as the 53 reciprocal scaling exponent. Refer to the property documentation of \l{GammaAdjust::gamma}{gamma} 54 for more details. 55 56 \table 57 \header 58 \li Source 59 \li Effect applied 60 \row 61 \li \image Original_bug.png 62 \li \image GammaAdjust_bug.png 63 \endtable 64 65 \note This effect is available when running with OpenGL. 66 67 \section1 Example 68 69 The following example shows how to apply the effect. 70 \snippet GammaAdjust-example.qml example 71 72*/ 73Item { 74 id: rootItem 75 76 /*! 77 This property defines the source item for which the luminance is going to be 78 adjusted. 79 80 \note It is not supported to let the effect include itself, for 81 instance by setting source to the effect's parent. 82 */ 83 property variant source 84 85 /*! 86 This property defines the change factor for how the luminance of each pixel 87 is altered according to the equation: 88 89 \code 90luminance = pow(original_luminance, 1.0 / gamma); // The luminance is assumed to be between 0.0 and 1.0 91 \endcode 92 93 Setting the gamma values under 1.0 makes the image darker, the values 94 above 1.0 lighten it. 95 96 The value ranges from 0.0 (darkest) to inf (lightest). By default, the 97 property is set to \c 1.0 (no change). 98 99 \table 100 \header 101 \li Output examples with different gamma values 102 \li 103 \li 104 \row 105 \li \image GammaAdjust_gamma1.png 106 \li \image GammaAdjust_gamma2.png 107 \li \image GammaAdjust_gamma3.png 108 \row 109 \li \b { gamma: 0.5 } 110 \li \b { gamma: 1.0 } 111 \li \b { gamma: 2.0 } 112 \endtable 113 114 \table 115 \header 116 \li Pixel luminance curves of the above images. 117 \li 118 \li 119 \row 120 \li \image GammaAdjust_gamma1_graph.png 121 \li \image GammaAdjust_gamma2_graph.png 122 \li \image GammaAdjust_gamma3_graph.png 123 \row 124 \li Red curve: default gamma (1.0) 125 \li 126 \li 127 \row 128 \li Yellow curve: effect applied 129 \li 130 \li 131 \row 132 \li X-axis: pixel original luminance 133 \li 134 \li 135 \row 136 \li Y-axis: pixel luminance with effect applied 137 \li 138 \li 139 \endtable 140 141 */ 142 property real gamma: 1.0 143 144 /*! 145 This property allows the effect output pixels to be cached in order to 146 improve the rendering performance. 147 148 Every time the source or effect properties are changed, the pixels in 149 the cache must be updated. Memory consumption is increased, because an 150 extra buffer of memory is required for storing the effect output. 151 152 It is recommended to disable the cache when the source or the effect 153 properties are animated. 154 155 By default, the property is set to \c false. 156 */ 157 property bool cached: false 158 159 SourceProxy { 160 id: sourceProxy 161 input: rootItem.source 162 interpolation: input && input.smooth ? SourceProxy.LinearInterpolation : SourceProxy.NearestInterpolation 163 } 164 165 ShaderEffectSource { 166 id: cacheItem 167 anchors.fill: parent 168 visible: rootItem.cached 169 smooth: true 170 sourceItem: shaderItem 171 live: true 172 hideSource: visible 173 } 174 175 ShaderEffect { 176 id: shaderItem 177 property variant source: sourceProxy.output 178 property real gamma: 1.0 / Math.max(rootItem.gamma, 0.0001) 179 180 anchors.fill: parent 181 182 fragmentShader: "qrc:/qt-project.org/imports/QtGraphicalEffects/shaders/gammaadjust.frag" 183 } 184} 185