RadChart Item Selection via binding

[Richard]

Hi All,

Is it possible to have a pie segement selected using binding?  I have a class that has an IsSelected property that I want to reflect on various views.  One of these views is a pie chart which hosts multiple items based on this class and I want 1 or more segements to be shown selected based on this property.  I can set the IsSelected property in the SelectionChanged event of chart, but I want to reflect the change when the instance is selected in another view.  Would perfer to do this using binding, but will put in any suggestion in the code behind. 

I know I could manually wire up the IsSelected property change event, but this seems a bit of a hack tho.

Regards

Richard....

[Giuseppe]

Hi Richard,

Currently it is not possible to apply selection through bindings -- you can either select the slice through user interaction with the mouse, or you can use the selection API to apply selection from code-behind (ChartArea.SelectItem(...) method overloads).


Kind regards,
Freddie
the Telerik team

[Eirik H]

I want to have the item with the largest value selected by default and I'm populating the pie chart from code behind:

Me.PieChart.DefaultView.ChartArea.DataSeries.Clear()
Dim series As DataSeries = New DataSeries

series.Definition = Me.PieChart.DefaultSeriesDefinition

 

 Dim i As Integer = 0

 Dim _highestIdx As Integer = -1

 

For Each curVal As Double In curValues

 If (_highestIdx < 0) Then

 _highestIdx = i

 Else

  If (curVal > curValues(i - 1)) Then

   _highestIdx = i

  End If

 End If

 series.Add(New DataPoint(curVal) With {.Label = "Level " & (i + 1).ToString})

 i += 1

Next

 

Me.PieChart.DefaultView.ChartArea.DataSeries.Add(series)

Me.PieChart.DefaultView.ChartArea.SelectItem(_highestIdx)

However, using ChartArea.SelectItem right after adding the new DataSeries doesn't work. If I (for testing purposes) try to do Me.PieChart.DefaultView.ChartArea.SelectItem(_highestIdx)
in the PieChart.MouseEnter event, the item gets selected properly.

It looks like you can't set an item as selected while RadChart is busy with rendering the new dataseries?
Is there an event I can subscribe to which triggers when this operation is finished?


[Eirik H]

I submitted a support request for this and the solution for me was to hook on to the LayoutUpdated event.

Public Sub HighlightHighestItem()
    If (_highestIdx >= 0) Then
        Me.PieChart.DefaultView.ChartArea.SelectItem(_highestIdx)
    End If
End Sub

Private Sub PieChart_LayoutUpdated(ByVal sender As Object, ByVal e As System.EventArgs) Handles PieChart.LayoutUpdated
    If (Me.PieChart.DefaultView.ChartArea.DataSeries.Count > 0) Then
        Me.HighlightHighestItem()
    End If
End Sub

[Jolly]

Eirik H, thank you very much for your last post!

I encountered this problem too, and solved it with this LayoutUpdated event you provided here. Thanks again!

[Yezdi]

I need a similar feature where each individual pie chart item can be bound to a ViewModel IsSelected boolean property. Please let me know the best solution for this.