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| |
| import QtQuick 2.12 |
| import QtQuick.Window 2.12 |
| import QtGraphicalEffects.private 1.12 |
| |
| /*! |
| \qmltype GaussianBlur |
| \inqmlmodule QtGraphicalEffects |
| \since QtGraphicalEffects 1.0 |
| \inherits QtQuick2::Item |
| \ingroup qtgraphicaleffects-blur |
| \brief Applies a higher quality blur effect. |
| |
| GaussianBlur effect softens the image by blurring it with an algorithm that |
| uses the Gaussian function to calculate the effect. The effect produces |
| higher quality than \l{QtGraphicalEffects::FastBlur}{FastBlur}, but is |
| slower to render. |
| |
| \table |
| \header |
| \li Source |
| \li Effect applied |
| \row |
| \li \image Original_bug.png |
| \li \image GaussianBlur_bug.png |
| \endtable |
| |
| \note This effect is available when running with OpenGL. |
| |
| \section1 Example |
| |
| The following example shows how to apply the effect. |
| \snippet GaussianBlur-example.qml example |
| |
| Performing blur live is a costly operation. Fullscreen gaussian blur |
| with even a moderate number of samples will only run at 60 fps on highend |
| graphics hardware. |
| |
| */ |
| Item { |
| id: root |
| |
| /*! |
| This property defines the source item that is going to be blurred. |
| |
| \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 distance of the neighboring pixels which |
| affect the blurring of an individual pixel. A larger radius increases |
| the blur effect. |
| |
| The ideal blur is achieved by selecting \c samples and \c radius such |
| that \c {samples = 1 + radius * 2}, such as: |
| |
| \table |
| \header \li Radius \li Samples |
| \row \li 0 \e{(no blur)} \li 1 |
| \row \li 1 \li 3 |
| \row \li 2 \li 5 |
| \row \li 3 \li 7 |
| \endtable |
| |
| The value ranges from 0.0 (no blur) to inf. By default, the property is |
| set to \c floor(samples / 2.0). |
| |
| \table |
| \header |
| \li Output examples with different radius values |
| \li |
| \li |
| \row |
| \li \image GaussianBlur_radius1.png |
| \li \image GaussianBlur_radius2.png |
| \li \image GaussianBlur_radius3.png |
| \row |
| \li \b { radius: 0 } |
| \li \b { radius: 4 } |
| \li \b { radius: 8 } |
| \row |
| \li \l samples: 16 |
| \li \l samples: 16 |
| \li \l samples: 16 |
| \row |
| \li \l deviation: 3 |
| \li \l deviation: 3 |
| \li \l deviation: 3 |
| \endtable |
| |
| */ |
| property real radius: Math.floor(samples / 2); |
| |
| /*! |
| This property defines how many samples are taken per pixel when blur |
| calculation is done. Larger value produces better quality, but is slower |
| to render. |
| |
| Ideally, this value should be twice as large as the highest required |
| radius value plus 1, for example, if the radius is animated between 0.0 |
| and 4.0, samples should be set to 9. |
| |
| By default, the property is set to \c 9. |
| |
| \note This property is not intended to be animated. Changing this property may |
| cause the underlying OpenGL shaders to be recompiled. |
| |
| */ |
| property int samples: 9 |
| |
| /*! |
| This property is a parameter to the gaussian function that is used when |
| calculating neighboring pixel weights for the blurring. A larger |
| deviation causes image to appear more blurry, but it also reduces the |
| quality of the blur. A very large deviation value causes the effect to |
| look a bit similar to what, for exmple, a box blur algorithm produces. A |
| too small deviation values makes the effect insignificant for the pixels |
| near the radius. |
| |
| \inlineimage GaussianBlur_deviation_graph.png |
| \caption The image above shows the Gaussian function with two different |
| deviation values, yellow (1) and cyan (2.7). The y-axis shows the |
| weights, the x-axis shows the pixel distance. |
| |
| The value ranges from 0.0 (no deviation) to inf (maximum deviation). By |
| default, devaition is binded to radius. When radius increases, deviation |
| is automatically increased linearly. With the radius value of 8, the |
| deviation default value becomes approximately 2.7034. This value |
| produces a compromise between the blur quality and overall blurriness. |
| |
| \table |
| \header |
| \li Output examples with different deviation values |
| \li |
| \li |
| \row |
| \li \image GaussianBlur_deviation1.png |
| \li \image GaussianBlur_deviation2.png |
| \li \image GaussianBlur_deviation3.png |
| \row |
| \li \b { deviation: 1 } |
| \li \b { deviation: 2 } |
| \li \b { deviation: 4 } |
| \row |
| \li \l radius: 8 |
| \li \l radius: 8 |
| \li \l radius: 8 |
| \row |
| \li \l samples: 16 |
| \li \l samples: 16 |
| \li \l samples: 16 |
| \endtable |
| |
| */ |
| property real deviation: (radius + 1) / 3.3333 |
| |
| /*! |
| This property defines the blur behavior near the edges of the item, |
| where the pixel blurring is affected by the pixels outside the source |
| edges. |
| |
| If the property is set to \c true, the pixels outside the source are |
| interpreted to be transparent, which is similar to OpenGL |
| clamp-to-border extension. The blur is expanded slightly outside the |
| effect item area. |
| |
| If the property is set to \c false, the pixels outside the source are |
| interpreted to contain the same color as the pixels at the edge of the |
| item, which is similar to OpenGL clamp-to-edge behavior. The blur does |
| not expand outside the effect item area. |
| |
| By default, the property is set to \c false. |
| |
| \table |
| \header |
| \li Output examples with different transparentBorder values |
| \li |
| \li |
| \row |
| \li \image GaussianBlur_transparentBorder1.png |
| \li \image GaussianBlur_transparentBorder2.png |
| \row |
| \li \b { transparentBorder: false } |
| \li \b { transparentBorder: true } |
| \row |
| \li \l radius: 8 |
| \li \l radius: 8 |
| \row |
| \li \l samples: 16 |
| \li \l samples: 16 |
| \row |
| \li \l deviation: 2.7 |
| \li \l deviation: 2.7 |
| \endtable |
| */ |
| property bool transparentBorder: false |
| |
| /*! |
| 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 |
| |
| |
| // private members... |
| /*! \internal */ |
| property int _paddedTexWidth: transparentBorder ? width + 2 * radius: width; |
| /*! \internal */ |
| property int _paddedTexHeight: transparentBorder ? height + 2 * radius: height; |
| /*! \internal */ |
| property int _kernelRadius: Math.max(0, samples / 2); |
| /*! \internal */ |
| property int _kernelSize: _kernelRadius * 2 + 1; |
| /*! \internal */ |
| property real _dpr: Screen.devicePixelRatio; |
| /*! \internal */ |
| property bool _alphaOnly: false; |
| /*! \internal */ |
| property var _maskSource: undefined |
| |
| /*! \internal */ |
| property alias _output: sourceProxy.output; |
| /*! \internal */ |
| property alias _outputRect: sourceProxy.sourceRect; |
| /*! \internal */ |
| property alias _color: verticalBlur.color; |
| /*! \internal */ |
| property real _thickness: 0; |
| |
| onSamplesChanged: _rebuildShaders(); |
| on_KernelSizeChanged: _rebuildShaders(); |
| onDeviationChanged: _rebuildShaders(); |
| on_DprChanged: _rebuildShaders(); |
| on_MaskSourceChanged: _rebuildShaders(); |
| Component.onCompleted: _rebuildShaders(); |
| |
| /*! \internal */ |
| function _rebuildShaders() { |
| var params = { |
| radius: _kernelRadius, |
| // Limit deviation to something very small avoid getting NaN in the shader. |
| deviation: Math.max(0.00001, deviation), |
| alphaOnly: root._alphaOnly, |
| masked: _maskSource != undefined, |
| fallback: root.radius != _kernelRadius |
| } |
| var shaders = ShaderBuilder.gaussianBlur(params); |
| horizontalBlur.fragmentShader = shaders.fragmentShader; |
| horizontalBlur.vertexShader = shaders.vertexShader; |
| } |
| |
| SourceProxy { |
| id: sourceProxy |
| interpolation: SourceProxy.LinearInterpolation |
| input: root.source |
| sourceRect: root.transparentBorder |
| ? Qt.rect(-root.radius, 0, root._paddedTexWidth, parent.height) |
| : Qt.rect(0, 0, 0, 0) |
| } |
| |
| ShaderEffect { |
| id: horizontalBlur |
| width: root.transparentBorder ? root._paddedTexWidth : root.width |
| height: root.height; |
| |
| // Used by all shaders |
| property Item source: sourceProxy.output; |
| property real spread: root.radius / root._kernelRadius; |
| property var dirstep: Qt.vector2d(1 / (root._paddedTexWidth * root._dpr), 0); |
| |
| // Used by fallback shader (sampleCount exceeds number of varyings) |
| property real deviation: root.deviation |
| |
| // Only in use for DropShadow and Glow |
| property color color: "white" |
| property real thickness: Math.max(0, Math.min(0.98, 1 - root._thickness * 0.98)); |
| |
| // Only in use for MaskedBlur |
| property var mask: root._maskSource; |
| |
| layer.enabled: true |
| layer.smooth: true |
| layer.sourceRect: root.transparentBorder |
| ? Qt.rect(0, -root.radius, width, root._paddedTexHeight) |
| : Qt.rect(0, 0, 0, 0) |
| visible: false |
| blending: false |
| } |
| |
| ShaderEffect { |
| id: verticalBlur |
| x: transparentBorder ? -root.radius : 0 |
| y: x; |
| width: root.transparentBorder ? root._paddedTexWidth: root.width |
| height: root.transparentBorder ? root._paddedTexHeight : root.height; |
| fragmentShader: horizontalBlur.fragmentShader |
| vertexShader: horizontalBlur.vertexShader |
| |
| property Item source: horizontalBlur |
| property real spread: horizontalBlur.spread |
| property var dirstep: Qt.vector2d(0, 1 / (root._paddedTexHeight * root._dpr)); |
| |
| property real deviation: horizontalBlur.deviation |
| |
| property color color: "black" |
| property real thickness: horizontalBlur.thickness; |
| |
| property var mask: horizontalBlur.mask; |
| |
| visible: true |
| } |
| |
| ShaderEffectSource { |
| id: cacheItem |
| anchors.fill: verticalBlur |
| visible: root.cached |
| smooth: true |
| sourceItem: verticalBlur |
| hideSource: visible |
| } |
| |
| } |