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/****************************************************************************
**
** Copyright (C) 2017 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt Graphical Effects module.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
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** $QT_END_LICENSE$
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****************************************************************************/
import QtQuick 2.12
import QtGraphicalEffects.private 1.12
/*!
\qmltype ZoomBlur
\inqmlmodule QtGraphicalEffects
\since QtGraphicalEffects 1.0
\inherits QtQuick2::Item
\ingroup qtgraphicaleffects-motion-blur
\brief Applies directional blur effect towards source items center point.
Effect creates perceived impression that the source item appears to be
moving towards the center point in Z-direction or that the camera appears
to be zooming rapidly. Other available motion blur effects are
\l{QtGraphicalEffects::DirectionalBlur}{DirectionalBlur}
and \l{QtGraphicalEffects::RadialBlur}{RadialBlur}.
\table
\header
\li Source
\li Effect applied
\row
\li \image Original_bug.png
\li \image ZoomBlur_bug.png
\endtable
\note This effect is available when running with OpenGL.
\section1 Example
The following example shows how to apply the effect.
\snippet ZoomBlur-example.qml example
*/
Item {
id: rootItem
/*!
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 maximum perceived amount of movement for each
pixel. The amount is smaller near the center and reaches the specified
value at the edges.
The quality of the blur depends on \l{ZoomBlur::samples}{samples}
property. If length value is large, more samples are needed to keep the
visual quality at high level.
The value ranges from 0.0 to inf. By default the property is set to \c
0.0 (no blur).
\table
\header
\li Output examples with different length values
\li
\li
\row
\li \image ZoomBlur_length1.png
\li \image ZoomBlur_length2.png
\li \image ZoomBlur_length3.png
\row
\li \b { length: 0.0 }
\li \b { length: 32.0 }
\li \b { length: 48.0 }
\row
\li \l samples: 24
\li \l samples: 24
\li \l samples: 24
\row
\li \l horizontalOffset: 0
\li \l horizontalOffset: 0
\li \l horizontalOffset: 0
\row
\li \l verticalOffset: 0
\li \l verticalOffset: 0
\li \l verticalOffset: 0
\endtable
*/
property real length: 0.0
/*!
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.
This property is not intended to be animated. Changing this property may
cause the underlying OpenGL shaders to be recompiled.
Allowed values are between 0 and inf (practical maximum depends on GPU).
By default the property is set to \c 0 (no samples).
*/
property int samples: 0
/*!
\qmlproperty real QtGraphicalEffects::ZoomBlur::horizontalOffset
\qmlproperty real QtGraphicalEffects::ZoomBlur::verticalOffset
These properties define an offset in pixels for the blur direction
center point.
The values range from -inf to inf. By default these properties are set
to \c 0.
\table
\header
\li Output examples with different horizontalOffset values
\li
\li
\row
\li \image ZoomBlur_horizontalOffset1.png
\li \image ZoomBlur_horizontalOffset2.png
\li \image ZoomBlur_horizontalOffset3.png
\row
\li \b { horizontalOffset: 100.0 }
\li \b { horizontalOffset: 0.0 }
\li \b { horizontalOffset: -100.0 }
\row
\li \l samples: 24
\li \l samples: 24
\li \l samples: 24
\row
\li \l length: 32
\li \l length: 32
\li \l length: 32
\row
\li \l verticalOffset: 0
\li \l verticalOffset: 0
\li \l verticalOffset: 0
\endtable
*/
property real horizontalOffset: 0.0
property real verticalOffset: 0.0
/*!
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.
*/
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
SourceProxy {
id: sourceProxy
input: rootItem.source
sourceRect: rootItem.transparentBorder ? Qt.rect(-1, -1, parent.width + 2.0, parent.height + 2.0) : Qt.rect(0, 0, 0, 0)
}
ShaderEffectSource {
id: cacheItem
anchors.fill: shaderItem
visible: rootItem.cached
smooth: true
sourceItem: shaderItem
live: true
hideSource: visible
}
ShaderEffect {
id: shaderItem
property variant source: sourceProxy.output
property variant center: Qt.point(0.5 + rootItem.horizontalOffset / width, 0.5 + rootItem.verticalOffset / height)
property real len: rootItem.length
property bool transparentBorder: rootItem.transparentBorder
property real samples: rootItem.samples
property real weight: 1.0 / Math.max(1.0, rootItem.samples)
property variant expandPixels: transparentBorder ? Qt.size(rootItem.samples, rootItem.samples) : Qt.size(0,0)
property variant expand: transparentBorder ? Qt.size(expandPixels.width / width, expandPixels.height / height) : Qt.size(0,0)
property variant delta: Qt.size(1.0 / rootItem.width, 1.0 / rootItem.height)
x: transparentBorder ? -expandPixels.width - 1 : 0
y: transparentBorder ? -expandPixels.height - 1 : 0
width: transparentBorder ? parent.width + 2.0 * expandPixels.width + 2 : parent.width
height: transparentBorder ? parent.height + 2.0 * expandPixels.height + 2 : parent.height
property string fragmentShaderSkeleton: "
varying highp vec2 qt_TexCoord0;
uniform highp float qt_Opacity;
uniform lowp sampler2D source;
uniform highp float len;
uniform highp float weight;
uniform highp float samples;
uniform highp vec2 center;
uniform highp vec2 expand;
uniform highp vec2 delta;
void main(void) {
mediump vec2 texCoord = qt_TexCoord0;
mediump vec2 centerCoord = center;
PLACEHOLDER_EXPAND_STEPS
highp vec2 dir = vec2(centerCoord.x - texCoord.s, centerCoord.y - texCoord.t);
dir /= max(1.0, length(dir) * 2.0);
highp vec2 shift = delta * len * dir * 2.0 / max(1.0, samples - 1.0);
gl_FragColor = vec4(0.0);
PLACEHOLDER_UNROLLED_LOOP
gl_FragColor *= weight * qt_Opacity;
}
"
function buildFragmentShader() {
var shader = ""
if (GraphicsInfo.profile == GraphicsInfo.OpenGLCoreProfile)
shader += "#version 150 core\n#define varying in\n#define gl_FragColor fragColor\n#define texture2D texture\nout vec4 fragColor;\n"
shader += fragmentShaderSkeleton
var expandSteps = ""
if (transparentBorder) {
expandSteps += "centerCoord = (centerCoord - expand) / (1.0 - 2.0 * expand);"
expandSteps += "texCoord = (texCoord - expand) / (1.0 - 2.0 * expand);"
}
var unrolledLoop = "gl_FragColor += texture2D(source, texCoord);\n"
if (rootItem.samples > 1) {
unrolledLoop = ""
for (var i = 0; i < rootItem.samples; i++)
unrolledLoop += "gl_FragColor += texture2D(source, texCoord); texCoord += shift;\n"
}
shader = shader.replace("PLACEHOLDER_EXPAND_STEPS", expandSteps)
fragmentShader = shader.replace("PLACEHOLDER_UNROLLED_LOOP", unrolledLoop)
}
onFragmentShaderChanged: sourceChanged()
onSamplesChanged: buildFragmentShader()
onTransparentBorderChanged: buildFragmentShader()
Component.onCompleted: buildFragmentShader()
}
}