Qml F1 Legends

Running the Example

To run the example from Qt Creator, open the Welcome mode and select the example from Examples. For more information, visit Building and Running an Example.

Using List Models as Data Sources

Let's define an empty ChartView first:

 ChartView {
     id: chartView
     title: "Driver Speeds, lap 1"
     anchors.fill: parent
     legend.alignment: Qt.AlignTop
     animationOptions: ChartView.SeriesAnimations
     antialiasing: true
 }

Our XmlListModel uses hard-coded test data. In a real application the data source would be a timing system.

 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();
         }
     }
 }

The data is parsed with a timer. The line series representing each driver are created on the fly.

 // 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;
         }
     }
 }

Example project @ code.qt.io