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/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt Virtual Keyboard module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:GPL$
** 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 General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3 or (at your option) any later version
** approved by the KDE Free Qt Foundation. The licenses are as published by
** the Free Software Foundation and appearing in the file LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/
import QtQuick 2.0
import "TraceUtils.js" as TraceUtils
/*!
\qmltype TraceCanvas
\inqmlmodule QtQuick.VirtualKeyboard.Styles
\brief A specialized Canvas type for rendering Trace objects.
\ingroup qtvirtualkeyboard-styles-qml
\inherits Canvas
\since QtQuick.VirtualKeyboard 2.0
This type provides capabilities for rendering Trace objects on the screen.
To make the Trace rendering available in the keyboard, this type must be
declared as the \l {KeyboardStyle::traceCanvasDelegate}
{KeyboardStyle.traceCanvasDelegate} component.
\code
traceCanvasDelegate: TraceCanvas {
}
\endcode
Custom drawing attributes can be initialized in the Canvas.available
signal. For example:
\code
onAvailableChanged: {
if (!available)
return;
var ctx = getContext("2d")
ctx.lineWidth = 8 * scaleHint
ctx.lineCap = "round"
ctx.strokeStyle = Qt.rgba(0xFF, 0xFF, 0xFF)
ctx.fillStyle = ctx.strokeStyle
}
\endcode
The type offers built-in options for Trace rendering. Currently
the following rendering options are available:
\list
\li \c renderSmoothedLine Renders smoothed line with round corners (the default)
\endlist
The rendering function can be changed with the renderFunction property.
\code
renderFunction: renderSmoothedLine
\endcode
Custom rendering function is also supported. Consider the following example:
\code
renderFunction: renderCustomLine
function renderCustomLine() {
getContext("2d")
var points = trace.points()
...
}
\endcode
*/
Canvas {
id: canvas
/*! Provides access to \l Trace object.
*/
property var trace
/*! Enables auto destruction mode.
If enabled, this item will be destroyed when the \c trace object is
destroyed.
The default value is false.
*/
property bool autoDestroy
/*! Specifies the approximate delay in milliseconds, counted from the beginning of the
auto destruction, before the object is to be destroyed.
This delay makes it possible, for example, to animate the item before destruction.
The default value is 0.
*/
property int autoDestroyDelay
/*! This property defines the rendering function.
The default value is \c renderSmoothedLine
*/
property var renderFunction: renderSmoothedLine
property int __renderPos
property bool __renderingEnabled
/*! Renders smoothed line with round corners.
This function is incremental and renders only the new part added to the Trace.
This function does not alter any of the canvas attributes (i.e. they can be set elsewhere.)
*/
function renderSmoothedLine() {
__renderPos = TraceUtils.renderSmoothedLine(getContext("2d"), trace, __renderPos)
}
onTraceChanged: if (trace === null && autoDestroy) destroy(autoDestroyDelay)
onAvailableChanged: {
__renderingEnabled = available
if (__renderingEnabled)
requestAnimationFrame(renderFunction)
}
Connections {
target: canvas.__renderingEnabled && trace ? trace : null
onLengthChanged: if (renderFunction) canvas.requestAnimationFrame(renderFunction)
onFinalChanged: if (renderFunction) canvas.requestAnimationFrame(renderFunction)
}
opacity: trace ? trace.opacity : 1.0
Behavior on opacity {
NumberAnimation {
duration: 1500
easing.type: Easing.InOutQuad
}
}
}
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