RoutedPropertyChangedEventHandler(Of T) Delegate
Represents methods that will handle various routed events that track property value changes.
Assembly: PresentationFramework (in PresentationFramework.dll)
'Declaration Public Delegate Sub RoutedPropertyChangedEventHandler(Of T) ( _ sender As Object, _ e As RoutedPropertyChangedEventArgs(Of T) _ )
The type of the property value where changes in value are reported.
- Type: System.Object
The object where the event handler is attached.
The following example defines and attaches a handler method for the ValueChanged event.
The handler is based on , and is defined in the second segment of the code example, with the type parameter of the generic constrained to Double.
Private Sub OnChildrenCountChanged(ByVal sender As Object, ByVal e As RoutedPropertyChangedEventArgs(Of Double)) Dim childrenCount As Integer = CInt(Fix(Math.Floor(e.NewValue + 0.5))) ' Update the children count... Dim g As AutoIndexingGrid = CType(LogicalTreeHelper.FindLogicalNode(myWindow, "TargetGrid"), AutoIndexingGrid) Do While g.Children.Count < childrenCount Dim c As New Control() g.Children.Add(c) c.Style = CType(c.FindResource("ImageWithBorder"), Style) Loop Do While g.Children.Count > childrenCount g.Children.Remove(g.Children(g.Children.Count - 1)) Loop ' Update TextBlock element displaying the count... Dim t As TextBlock = CType(LogicalTreeHelper.FindLogicalNode(myWindow, "ChildrenCountDisplay"), TextBlock) t.Text = childrenCount.ToString() End Sub
This particular example does not use the routed-event characteristic of the event; the event is handled on the same element that it is raised on. This is not always the case. For a routed event, it is possible that the source of the event is a different object than the object where the handler is attached.