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<td >Qt 5.12</td><td ><a href="qtcharts-index.html">Qt Charts</a></td><td ><a href="qtcharts-examples.html">Qt Charts Examples</a></td><td >Qml F1 Legends</td></tr></table><table class="buildversion"><tr>
<td id="buildversion" width="100%" align="right"><a href="qtcharts-index.html">Qt Charts | Commercial or GPLv3</a></td>
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<h3><a name="toc">Contents</a></h3>
<ul>
<li class="level1"><a href="#running-the-example">Running the Example</a></li>
<li class="level1"><a href="#using-list-models-as-data-sources">Using List Models as Data Sources</a></li>
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<h1 class="title">Qml F1 Legends</h1>
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<p>This application demonstrates how to use XmlListModel as a datasource for a Chart.</p>
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<p class="centerAlign"><img src="images/examples_qmlf1legends.png" alt="" /></p><a name="running-the-example"></a>
<h2 id="running-the-example">Running the Example</h2>
<p>To run the example from Qt Creator, open the <b>Welcome</b> mode and select the example from <b>Examples</b>. For more information, visit Building and Running an Example.</p>
<a name="using-list-models-as-data-sources"></a>
<h2 id="using-list-models-as-data-sources">Using List Models as Data Sources</h2>
<p>Let's define an empty <a href="qml-qtcharts-chartview.html">ChartView</a> first:</p>
<pre class="qml">
ChartView {
id: chartView
title: "Driver Speeds, lap 1"
anchors.fill: parent
legend.alignment: Qt.AlignTop
animationOptions: ChartView.SeriesAnimations
antialiasing: true
}
</pre>
<p>Our XmlListModel uses hard-coded test data. In a real application the data source would be a timing system.</p>
<pre class="qml">
XmlListModel {
// Hard-coded test data
xml: "<results><row><speedTrap>0</speedTrap><driver>Fittipaldi</driver><speed>104.12</speed></row>"
+"<row><speedTrap>0</speedTrap><driver>Stewart</driver><speed>106.12</speed></row>"
+"<row><speedTrap>0</speedTrap><driver>Hunt</driver><speed>106.12</speed></row>"
...
query: "/results/row"
XmlRole { name: "speedTrap"; query: "speedTrap/string()" }
XmlRole { name: "driver"; query: "driver/string()" }
XmlRole { name: "speed"; query: "speed/string()" }
}
// An example XmlListModel containing F1 legend drivers' speeds at speed traps
SpeedsXml {
id: speedsXml
onStatusChanged: {
if (status == XmlListModel.Ready) {
timer.start();
}
}
}
</pre>
<p>The data is parsed with a timer. The line series representing each driver are created on the fly.</p>
<pre class="qml">
// A timer to mimic refreshing the data dynamically
Timer {
id: timer
interval: 700
repeat: true
triggeredOnStart: true
running: false
onTriggered: {
currentIndex++;
if (currentIndex < speedsXml.count) {
// Check if there is a series for the data already
// (we are using driver name to identify series)
var lineSeries = chartView.series(speedsXml.get(currentIndex).driver);
if (!lineSeries) {
lineSeries = chartView.createSeries(ChartView.SeriesTypeLine,
speedsXml.get(currentIndex).driver);
chartView.axisY().min = 0;
chartView.axisY().max = 250;
chartView.axisY().tickCount = 6;
chartView.axisY().titleText = "speed (kph)";
chartView.axisX().titleText = "speed trap";
chartView.axisX().labelFormat = "%.0f";
}
lineSeries.append(speedsXml.get(currentIndex).speedTrap,
speedsXml.get(currentIndex).speed);
if (speedsXml.get(currentIndex).speedTrap > 3) {
chartView.axisX().max = Number(speedsXml.get(currentIndex).speedTrap) + 1;
chartView.axisX().min = chartView.axisX().max - 5;
} else {
chartView.axisX().max = 5;
chartView.axisX().min = 0;
}
chartView.axisX().tickCount = chartView.axisX().max - chartView.axisX().min + 1;
} else {
// No more data, change x-axis range to show all the data
timer.stop();
chartView.animationOptions = ChartView.AllAnimations;
chartView.axisX().min = 0;
chartView.axisX().max = speedsXml.get(currentIndex - 1).speedTrap;
}
}
}
</pre>
<p>Files:</p>
<ul>
<li><a href="qtcharts-qmlf1legends-main-cpp.html">qmlf1legends/main.cpp</a></li>
<li><a href="qtcharts-qmlf1legends-qml-qmlf1legends-speedsxml-qml.html">qmlf1legends/qml/qmlf1legends/SpeedsXml.qml</a></li>
<li><a href="qtcharts-qmlf1legends-qml-qmlf1legends-main-qml.html">qmlf1legends/qml/qmlf1legends/main.qml</a></li>
<li><a href="qtcharts-qmlf1legends-qmlf1legends-pro.html">qmlf1legends/qmlf1legends.pro</a></li>
<li><a href="qtcharts-qmlf1legends-resources-qrc.html">qmlf1legends/resources.qrc</a></li>
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