Selection

This help topic will demonstrate how you can make your charts more interactive by adding a selection behavior.

In order to utilize this behavior users simply have to add it to the chart's Controllers collection. For example:

Add Controller

• C#
• VB.NET

radChartView1.Controllers.Add(new ChartSelectionController());
radChartView1.SelectionMode = ChartSelectionMode.SingleDataPoint;
radChartView1.SelectedPointChanged += new ChartViewSelectedChangedEventHandler(radChartView1_SelectedPointChanged);

RadChartView1.Controllers.Add(New ChartSelectionController())
RadChartView1.SelectionMode = ChartSelectionMode.SingleDataPoint
AddHandler RadChartView1.SelectedPointChanged, AddressOf RadChartView1_SelectedPointChanged

The ChartSelectionController will be added automatically if the SelectionMode property of RadChartView control is set to one of available options.

ChartSelectionMode

• C#
• VB.NET

radChartView1.SelectionMode = ChartSelectionMode.SingleDataPoint;
radChartView1.SelectionMode = ChartSelectionMode.MultipleDataPoints;

radChartView1.SelectionMode = ChartSelectionMode.SingleDataPoint
radChartView1.SelectionMode = ChartSelectionMode.MultipleDataPoints

Here is a sample using PieSeries and multiple selection. When a slice is selected, it is being offsetted from the center:

Sliced Pie

• C#
• VB.NET

public ChartSelection()
{
    InitializeComponent();
    radChartView1.AreaType = ChartAreaType.Pie;
    PieSeries pieSeries = new PieSeries();
    pieSeries.ShowLabels = true;
    pieSeries.PointSize = new SizeF(15, 15);
    pieSeries.DataPoints.Add(new PieDataPoint(10));
    pieSeries.DataPoints.Add(new PieDataPoint(5));
    pieSeries.DataPoints.Add(new PieDataPoint(40));
    pieSeries.DataPoints.Add(new PieDataPoint(22));
    pieSeries.DataPoints.Add(new PieDataPoint(11));
    pieSeries.DataPoints.Add(new PieDataPoint(20));
    radChartView1.Series.Add(pieSeries);
    radChartView1.Controllers.Add(new ChartSelectionController());
    radChartView1.SelectionMode = ChartSelectionMode.MultipleDataPoints;
    radChartView1.SelectedPointChanged += new ChartViewSelectedChangedEventHandler(radChartView1_SelectedPointChanged);
}
void radChartView1_SelectedPointChanged(object sender, ChartViewSelectedPointChangedEventArgs args)
{
    if (args.NewSelectedPoint != null)
    {
        UpdateSelectedPoint(args.NewSelectedPoint);
    }
    if (args.OldSelectedPoint != null)
    {
        UpdateSelectedPoint(args.OldSelectedPoint);
    }
}
void UpdateSelectedPoint(DataPoint point)
{
    PieDataPoint pieDataPoint = point as PieDataPoint;
    if (pieDataPoint != null)
    {
        if (pieDataPoint.IsSelected)
        {
            pieDataPoint.OffsetFromCenter = 0.1;
        }
        else
        {
            pieDataPoint.OffsetFromCenter = 0;
        }
    }
}

Public Sub New()
    InitializeComponent()
    radChartView1.AreaType = ChartAreaType.Pie
    Dim pieSeries As New PieSeries()
    pieSeries.ShowLabels = True
    pieSeries.PointSize = New SizeF(15, 15)
    pieSeries.DataPoints.Add(New PieDataPoint(10))
    pieSeries.DataPoints.Add(New PieDataPoint(5))
    pieSeries.DataPoints.Add(New PieDataPoint(40))
    pieSeries.DataPoints.Add(New PieDataPoint(22))
    pieSeries.DataPoints.Add(New PieDataPoint(11))
    pieSeries.DataPoints.Add(New PieDataPoint(20))
    radChartView1.Series.Add(pieSeries)
    RadChartView1.Controllers.Add(New ChartSelectionController())
    RadChartView1.SelectionMode = ChartSelectionMode.MultipleDataPoints
    AddHandler RadChartView1.SelectedPointChanged, AddressOf RadChartView1_SelectedPointChanged
End Sub
Private Sub RadChartView1_SelectedPointChanged(sender As Object, args As ChartViewSelectedPointChangedEventArgs)
    If args.NewSelectedPoint IsNot Nothing Then
        UpdateSelectedPoint(args.NewSelectedPoint)
    End If
    If args.OldSelectedPoint IsNot Nothing Then
        UpdateSelectedPoint(args.OldSelectedPoint)
    End If
End Sub
Private Sub UpdateSelectedPoint(point As DataPoint)
    Dim pieDataPoint As PieDataPoint = TryCast(point, PieDataPoint)
    If pieDataPoint IsNot Nothing Then
        If pieDataPoint.IsSelected Then
            pieDataPoint.OffsetFromCenter = 0.1
        Else
            pieDataPoint.OffsetFromCenter = 0
        End If
    End If
End Sub

Figure 2: Sliced Pie