Hello Steve,
Thank you for writing back.
It is normal that the
LabelFormatting event is fired a lot of times as it is responsible for the correct label's style. By using the provided code snippet I have noticed that the label elements are constantly moving horizontally as their
LayoutSlot is changed when adjusting the
PositionOffset property. By calling the
GetLayoutSlot method of the
BarLabelElement, the
LabelFormatting events firing increases as well.
RadChartView provides a built-in mechanism for resolving labels overlapping with the
SmartLabelsController. You can add the controller to the
Controllers collection of
RadChartView and it will optimize the arrangement of the labels in a way that there will be less overlaps. It is possible to create a custom
SmartLabelsStrategy and position the labels manually. The following example shows a sample approach how you can position the labels in the top part of the chart:
Public Class MyStrategy
Inherits SmartLabelsStrategyBase
Public Overrides Sub CalculateLocations(series As ChartSeriesCollection, plotArea As Rectangle)
Dim labels As New List(Of LabelElement)()
Dim overlaps As New List(Of Integer)()
Dim x As Integer = 70
Dim y As Integer = 30
Dim spacing As Integer = 6
For Each chartSeries As ChartSeries In series
If Not chartSeries.ShowLabels OrElse Not chartSeries.IsVisible Then
Continue For
End If
For Each point As DataPointElement In chartSeries.Children
Dim label As LabelElement = DirectCast(point.Children(0), LabelElement)
Dim labelRect As Rectangle = ChartRenderer.ToRectangle(label.GetLayoutSlot())
Dim newRect = New Rectangle(x, y, labelRect.Width, labelRect.Height)
x += spacing + labelRect.Width
If x + spacing + labelRect.Width > plotArea.Width - 100 Then
y += spacing + labelRect.Height
x = 70
End If
label.SmartRectangle = newRect
labels.Add(label)
Next
Next
End Sub
End Class
Public Class MySmartLabelsController
Inherits SmartLabelsController
Public Overrides Sub CalculateLabelsPositions(series As ChartSeriesCollection, plotArea As Rectangle)
If Me.Strategy IsNot Nothing Then
Me.Strategy.CalculateLocations(series, plotArea)
End If
End Sub
End Class
As to the labels' size, note that they are auto sized to fit their content considering the font. If you need to enlarge the label, it is necessary to increase its
LayoutSlot which requires creating a custom
BarLabelElement:
I hope this information helps. If you have any additional questions, please let me know.
Regards,
Dess
Telerik
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