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/****************************************************************************
**
** Copyright (C) 2017 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** 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.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
** * Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** * Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in
** the documentation and/or other materials provided with the
** distribution.
** * Neither the name of The Qt Company Ltd nor the names of its
** contributors may be used to endorse or promote products derived
** from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/
//![0]
import QtQuick 2.0
Rectangle {
width: 480
height: 320
property int callsToUpdateMinimumWidth: 0
property bool optimize: true
property int currentTextModel: 0
property var columnTexts: [
["Click on either", "rectangle above", "and note how the counter", "below updates", "significantly faster using the", "regular (non-optimized)", "implementation"],
["The width", "of this column", "is", "no wider than the", "widest item"],
["Note how using Qt.callLater()", "the minimum width is", "calculated a bare-minimum", "number", "of times"]
]
Text {
x: 20; y: 280
text: "Times minimum width has been calculated: " + callsToUpdateMinimumWidth
}
Row {
y: 25; spacing: 30; anchors.horizontalCenter: parent.horizontalCenter
Rectangle {
width: 200; height: 50; color: "lightgreen"
Text { text: "Optimized behavior\nusing Qt.callLater()"; anchors.centerIn: parent }
MouseArea { anchors.fill: parent; onClicked: { optimize = true; currentTextModel++ } }
}
Rectangle {
width: 200; height: 50; color: "lightblue"
Text { text: "Regular behavior"; anchors.centerIn: parent}
MouseArea { anchors.fill: parent; onClicked: { optimize = false; currentTextModel++ } }
}
}
Column {
id: column
anchors.centerIn: parent
onChildrenChanged: optimize ? Qt.callLater(updateMinimumWidth) : updateMinimumWidth()
property int widestChild
function updateMinimumWidth() {
callsToUpdateMinimumWidth++
var w = 0;
for (var i in children) {
var child = children[i];
if (child.implicitWidth > w) {
w = child.implicitWidth;
}
}
widestChild = w;
}
Repeater {
id: repeater
model: columnTexts[currentTextModel%3]
delegate: Text {
color: "white"
text: modelData
width: column.widestChild
horizontalAlignment: Text.Center
Rectangle { anchors.fill: parent; z: -1; color: index%2 ? "gray" : "darkgray" }
}
}
}
}
//![0]
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