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libqt5raspi/debian/usr/local/qt5raspi-5.12.5/qml/QtGraphicalEffects/GaussianBlur.qml

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/****************************************************************************
**
** Copyright (C) 2017 The Qt Company Ltd.
** Copyright (C) 2017 Jolla Ltd, author: <gunnar.sletta@jollamobile.com>
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt Graphical Effects module.
**
** $QT_BEGIN_LICENSE:LGPL$
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** packaging of this file. Please review the following information to
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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 int _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
}
}