295 lines
9.5 KiB
QML
295 lines
9.5 KiB
QML
/****************************************************************************
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**
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** Copyright (C) 2017 The Qt Company Ltd.
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** Copyright (C) 2017 Jolla Ltd, author: <gunnar.sletta@jollamobile.com>
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** Contact: https://www.qt.io/licensing/
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**
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** This file is part of the Qt Graphical Effects module.
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**
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** $QT_BEGIN_LICENSE:LGPL$
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and The Qt Company. For licensing terms
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** and conditions see https://www.qt.io/terms-conditions. For further
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** information use the contact form at https://www.qt.io/contact-us.
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**
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** GNU Lesser General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU Lesser
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** General Public License version 3 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL3 included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU Lesser General Public License version 3 requirements
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** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
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**
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** GNU General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU
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** General Public License version 2.0 or (at your option) the GNU General
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** Public license version 3 or any later version approved by the KDE Free
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** Qt Foundation. The licenses are as published by the Free Software
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** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
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** included in the packaging of this file. Please review the following
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** information to ensure the GNU General Public License requirements will
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** be met: https://www.gnu.org/licenses/gpl-2.0.html and
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** https://www.gnu.org/licenses/gpl-3.0.html.
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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import QtQuick 2.12
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import QtGraphicalEffects.private 1.12
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/*!
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\qmltype Glow
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\inqmlmodule QtGraphicalEffects
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\since QtGraphicalEffects 1.0
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\inherits QtQuick2::Item
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\ingroup qtgraphicaleffects-glow
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\brief Generates a halo like glow around the source item.
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The Glow effect blurs the alpha channel of the source and colorizes it
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with \l {Glow::color}{color} and places it behind the source, resulting in a halo or glow
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around the object. The quality of the blurred edge can be controlled using
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\l samples and \l radius and the strength of the glow can be changed using
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\l spread.
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\table
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\header
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\li Source
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\li Effect applied
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\row
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\li \image Original_butterfly_black.png
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\li \image Glow_butterfly.png
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\endtable
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The glow is created by blurring the image live using a gaussian blur.
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Performing blur live is a costly operation. Fullscreen gaussian blur with
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even a moderate number of samples will only run at 60 fps on highend
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graphics hardware.
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\note This effect is available when running with OpenGL.
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\section1 Example
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The following example shows how to apply the effect.
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\snippet Glow-example.qml example
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*/
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Item {
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id: root
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DropShadowBase {
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id: dps
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anchors.fill: parent
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color: "white"
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spread: 0.5
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horizontalOffset: 0
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verticalOffset: 0
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}
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/*!
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This property defines the source item that is going to be used as source
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for the generated glow.
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\note It is not supported to let the effect include itself, for
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instance by setting source to the effect's parent.
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*/
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property alias source: dps.source
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/*!
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Radius defines the softness of the glow. A larger radius causes the
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edges of the glow to appear more blurry.
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Depending on the radius value, value of the \l{Glow::samples}{samples}
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should be set to sufficiently large to ensure the visual quality.
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The ideal blur is achieved by selecting \c samples and \c radius such
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that \c {samples = 1 + radius * 2}, such as:
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\table
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\header \li Radius \li Samples
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\row \li 0 \e{(no blur)} \li 1
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\row \li 1 \li 3
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\row \li 2 \li 5
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\row \li 3 \li 7
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\endtable
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By default, the property is set to \c {floor(samples/2)}.
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\table
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\header
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\li Output examples with different radius values
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\li
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\li
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\row
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\li \image Glow_radius1.png
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\li \image Glow_radius2.png
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\li \image Glow_radius3.png
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\row
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\li \b { radius: 0 }
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\li \b { radius: 6 }
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\li \b { radius: 12 }
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\row
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\li \l samples: 25
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\li \l samples: 25
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\li \l samples: 25
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\row
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\li \l color: #ffffff
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\li \l color: #ffffff
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\li \l color: #ffffff
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\row
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\li \l spread: 0
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\li \l spread: 0
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\li \l spread: 0
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\endtable
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*/
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property alias radius: dps.radius
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/*!
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This property defines how many samples are taken per pixel when edge
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softening blur calculation is done. Larger value produces better
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quality, but is slower to render.
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Ideally, this value should be twice as large as the highest required
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radius value plus one, such as:
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\table
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\header \li Radius \li Samples
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\row \li 0 \e{(no blur)} \li 1
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\row \li 1 \li 3
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\row \li 2 \li 5
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\row \li 3 \li 7
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\endtable
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By default, the property is set to \c 9.
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This property is not intended to be animated. Changing this property will
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cause the underlying OpenGL shaders to be recompiled.
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*/
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property alias samples: dps.samples
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/*!
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This property defines how large part of the glow color is strengthened
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near the source edges.
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The values range from 0.0 to 1.0. By default, the property is set to \c
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0.5.
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\note The implementation is optimized for medium and low spread values.
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Depending on the source, spread values closer to 1.0 may yield visually
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asymmetrical results.
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\table
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\header
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\li Output examples with different spread values
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\li
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\li
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\row
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\li \image Glow_spread1.png
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\li \image Glow_spread2.png
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\li \image Glow_spread3.png
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\row
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\li \b { spread: 0.0 }
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\li \b { spread: 0.5 }
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\li \b { spread: 1.0 }
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\row
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\li \l radius: 8
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\li \l radius: 8
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\li \l radius: 8
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\row
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\li \l samples: 17
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\li \l samples: 17
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\li \l samples: 17
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\row
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\li \l color: #ffffff
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\li \l color: #ffffff
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\li \l color: #ffffff
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\endtable
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*/
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property alias spread: dps.spread
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/*!
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This property defines the RGBA color value which is used for the glow.
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By default, the property is set to \c "white".
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\table
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\header
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\li Output examples with different color values
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\li
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\li
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\row
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\li \image Glow_color1.png
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\li \image Glow_color2.png
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\li \image Glow_color3.png
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\row
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\li \b { color: #ffffff }
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\li \b { color: #00ff00 }
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\li \b { color: #aa00ff00 }
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\row
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\li \l radius: 8
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\li \l radius: 8
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\li \l radius: 8
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\row
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\li \l samples: 17
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\li \l samples: 17
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\li \l samples: 17
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\row
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\li \l spread: 0.5
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\li \l spread: 0.5
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\li \l spread: 0.5
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\endtable
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*/
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property alias color: dps.color
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/*!
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\internal
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Starting Qt 5.6, this property has no effect. It is left here
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for source compatibility only.
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### Qt 6: remove
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*/
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property bool fast: false
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/*!
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This property allows the effect output pixels to be cached in order to
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improve the rendering performance.
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Every time the source or effect properties are changed, the pixels in
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the cache must be updated. Memory consumption is increased, because an
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extra buffer of memory is required for storing the effect output.
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It is recommended to disable the cache when the source or the effect
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properties are animated.
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By default, the property is set to \c false.
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*/
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property alias cached: dps.cached
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/*!
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This property determines whether or not the effect has a transparent
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border.
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When set to \c true, the exterior of the item is padded with a
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transparent edge, making sampling outside the source texture use
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transparency instead of the edge pixels. Without this property, an
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image which has opaque edges will not get a blurred edge.
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By default, the property is set to \c true. Set it to false if the source
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already has a transparent edge to make the blurring a tiny bit faster.
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In the snippet below, the Rectangle on the left has transparent borders
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and has blurred edges, whereas the Rectangle on the right does not.
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\snippet Glow-transparentBorder-example.qml example
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\image Glow-transparentBorder.png
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*/
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property alias transparentBorder: dps.transparentBorder
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}
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