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// Copyright (C) 2017 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
//![0]
import QtQuick
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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