- Qt 6.4
- Qt Charts
- Qt Charts Examples
- Qml Polar Chart
- Qt Charts | Commercial or GPLv3

# Qml Polar Chart

This is a demonstration on how to use a polar chart in your QML application.

#### 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 Polar Charts in Qt Quick Applications

We begin with a chart that has a spline series and a scatter series with random data. Both series use the same axes.

     PolarChartView {
         title: "Two Series, Common Axes"
         anchors.fill: parent
         legend.visible: false
         antialiasing: true

         ValueAxis {
             id: axisAngular
             min: 0
             max: 20
             tickCount: 9
         }

         ValueAxis {
             id: axisRadial
             min: -0.5
             max: 1.5
         }

         SplineSeries {
             id: series1
             axisAngular: axisAngular
             axisRadial: axisRadial
             pointsVisible: true
         }

         ScatterSeries {
             id: series2
             axisAngular: axisAngular
             axisRadial: axisRadial
             markerSize: 10
         }
     }

     // Add data dynamically to the series
     Component.onCompleted: {
         for (var i = 0; i <= 20; i++) {
             series1.append(i, Math.random());
             series2.append(i, Math.random());
         }
     }

The next example shows a chart with some accurate historical data for which we need to use a DateTimeAxis and a AreaSeries.

     PolarChartView {
         title: "Historical Area Series"
         anchors.fill: parent
         legend.visible: false
         antialiasing: true

         DateTimeAxis {
             id: axis1
             format: "yyyy MMM"
             tickCount: 13
         }
         ValueAxis {
             id: axis2
         }
         LineSeries {
             id: lowerLine
             axisAngular: axis1
             axisRadial: axis2

             // Please note that month in JavaScript months are zero based, so 2 means March
             XYPoint { x: toMsecsSinceEpoch(new Date(1950, 0, 1)); y: 15 }
             XYPoint { x: toMsecsSinceEpoch(new Date(1962, 4, 1)); y: 35 }
             XYPoint { x: toMsecsSinceEpoch(new Date(1970, 0, 1)); y: 50 }
             XYPoint { x: toMsecsSinceEpoch(new Date(1978, 2, 1)); y: 75 }
             XYPoint { x: toMsecsSinceEpoch(new Date(1987, 11, 1)); y: 102 }
             XYPoint { x: toMsecsSinceEpoch(new Date(1992, 1, 1)); y: 132 }
             XYPoint { x: toMsecsSinceEpoch(new Date(1998, 7, 1)); y: 100 }
             XYPoint { x: toMsecsSinceEpoch(new Date(2002, 4, 1)); y: 120 }
             XYPoint { x: toMsecsSinceEpoch(new Date(2012, 8, 1)); y: 140 }
             XYPoint { x: toMsecsSinceEpoch(new Date(2013, 5, 1)); y: 150 }
         }
         LineSeries {
             id: upperLine
             axisAngular: axis1
             axisRadial: axis2

             // Please note that month in JavaScript months are zero based, so 2 means March
             XYPoint { x: toMsecsSinceEpoch(new Date(1950, 0, 1)); y: 30 }
             XYPoint { x: toMsecsSinceEpoch(new Date(1962, 4, 1)); y: 55 }
             XYPoint { x: toMsecsSinceEpoch(new Date(1970, 0, 1)); y: 80 }
             XYPoint { x: toMsecsSinceEpoch(new Date(1978, 2, 1)); y: 105 }
             XYPoint { x: toMsecsSinceEpoch(new Date(1987, 11, 1)); y: 125 }
             XYPoint { x: toMsecsSinceEpoch(new Date(1992, 1, 1)); y: 160 }
             XYPoint { x: toMsecsSinceEpoch(new Date(1998, 7, 1)); y: 140 }
             XYPoint { x: toMsecsSinceEpoch(new Date(2002, 4, 1)); y: 140 }
             XYPoint { x: toMsecsSinceEpoch(new Date(2012, 8, 1)); y: 170 }
             XYPoint { x: toMsecsSinceEpoch(new Date(2013, 5, 1)); y: 200 }
         }
         AreaSeries {
             axisAngular: axis1
             axisRadial: axis2
             lowerSeries: lowerLine
             upperSeries: upperLine
         }
     }
     // DateTimeAxis is based on QDateTimes so we must convert our JavaScript dates to
     // milliseconds since epoch to make them match the DateTimeAxis values
     function toMsecsSinceEpoch(date) {
         var msecs = date.getTime();
         return msecs;
     }

And the final example with a chart that uses a CategoryAxis to make the data easier to understand.

     PolarChartView {
         title: "Numerical Data for Dummies"
         anchors.fill: parent
         legend.visible: false
         antialiasing: true

         LineSeries {
             axisRadial: CategoryAxis {
                 min: 0
                 max: 30
                 CategoryRange {
                     label: "critical"
                     endValue: 2
                 }
                 CategoryRange {
                     label: "low"
                     endValue: 7
                 }
                 CategoryRange {
                     label: "normal"
                     endValue: 12
                 }
                 CategoryRange {
                     label: "high"
                     endValue: 18
                 }
                 CategoryRange {
                     label: "extremely high"
                     endValue: 30
                 }
             }

             axisAngular: ValueAxis {
                 tickCount: 13
             }

             XYPoint { x: 0; y: 4.3 }
             XYPoint { x: 1; y: 4.1 }
             XYPoint { x: 2; y: 4.7 }
             XYPoint { x: 3; y: 3.9 }
             XYPoint { x: 4; y: 5.2 }
             XYPoint { x: 5; y: 5.3 }
             XYPoint { x: 6; y: 6.1 }
             XYPoint { x: 7; y: 7.7 }
             XYPoint { x: 8; y: 12.9 }
             XYPoint { x: 9; y: 19.2 }
         }
     }

Example project @ code.qt.io