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| |
| import QtQuick 2.12 |
| import QtGraphicalEffects.private 1.12 |
| |
| /*! |
| \qmltype GammaAdjust |
| \inqmlmodule QtGraphicalEffects |
| \since QtGraphicalEffects 1.0 |
| \inherits QtQuick2::Item |
| \ingroup qtgraphicaleffects-color |
| \brief Alters the luminance of the source item. |
| |
| GammaAdjust is applied to each pixel according to the curve which is |
| pre-defined as a power-law expression, where the property gamma is used as the |
| reciprocal scaling exponent. Refer to the property documentation of \l{GammaAdjust::gamma}{gamma} |
| for more details. |
| |
| \table |
| \header |
| \li Source |
| \li Effect applied |
| \row |
| \li \image Original_bug.png |
| \li \image GammaAdjust_bug.png |
| \endtable |
| |
| \note This effect is available when running with OpenGL. |
| |
| \section1 Example |
| |
| The following example shows how to apply the effect. |
| \snippet GammaAdjust-example.qml example |
| |
| */ |
| Item { |
| id: rootItem |
| |
| /*! |
| This property defines the source item for which the luminance is going to be |
| adjusted. |
| |
| \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 the change factor for how the luminance of each pixel |
| is altered according to the equation: |
| |
| \code |
| luminance = pow(original_luminance, 1.0 / gamma); // The luminance is assumed to be between 0.0 and 1.0 |
| \endcode |
| |
| Setting the gamma values under 1.0 makes the image darker, the values |
| above 1.0 lighten it. |
| |
| The value ranges from 0.0 (darkest) to inf (lightest). By default, the |
| property is set to \c 1.0 (no change). |
| |
| \table |
| \header |
| \li Output examples with different gamma values |
| \li |
| \li |
| \row |
| \li \image GammaAdjust_gamma1.png |
| \li \image GammaAdjust_gamma2.png |
| \li \image GammaAdjust_gamma3.png |
| \row |
| \li \b { gamma: 0.5 } |
| \li \b { gamma: 1.0 } |
| \li \b { gamma: 2.0 } |
| \endtable |
| |
| \table |
| \header |
| \li Pixel luminance curves of the above images. |
| \li |
| \li |
| \row |
| \li \image GammaAdjust_gamma1_graph.png |
| \li \image GammaAdjust_gamma2_graph.png |
| \li \image GammaAdjust_gamma3_graph.png |
| \row |
| \li Red curve: default gamma (1.0) |
| \li |
| \li |
| \row |
| \li Yellow curve: effect applied |
| \li |
| \li |
| \row |
| \li X-axis: pixel original luminance |
| \li |
| \li |
| \row |
| \li Y-axis: pixel luminance with effect applied |
| \li |
| \li |
| \endtable |
| |
| */ |
| property real gamma: 1.0 |
| |
| /*! |
| 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 |
| interpolation: input && input.smooth ? SourceProxy.LinearInterpolation : SourceProxy.NearestInterpolation |
| } |
| |
| 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 gamma: 1.0 / Math.max(rootItem.gamma, 0.0001) |
| |
| anchors.fill: parent |
| |
| fragmentShader: "qrc:/qt-project.org/imports/QtGraphicalEffects/shaders/gammaadjust.frag" |
| } |
| } |