RoutedPropertyChangedEventHandler<T> RoutedPropertyChangedEventHandler<T> RoutedPropertyChangedEventHandler<T> RoutedPropertyChangedEventHandler<T> Delegate


Represents methods that will handle various routed events that track property value changes.

generic <typename T>
public delegate void RoutedPropertyChangedEventHandler(System::Object ^ sender, RoutedPropertyChangedEventArgs<T> ^ e);
public delegate void RoutedPropertyChangedEventHandler<T>(object sender, RoutedPropertyChangedEventArgs<T> e);
type RoutedPropertyChangedEventHandler<'T> = delegate of obj * RoutedPropertyChangedEventArgs<'T> -> unit
Public Delegate Sub RoutedPropertyChangedEventHandler(Of T)(sender As Object, e As RoutedPropertyChangedEventArgs(Of T))

Type Parameters


The type of the property value where changes in value are reported.


Object Object Object Object

The object where the event handler is attached.

RoutedPropertyChangedEventArgs<T> RoutedPropertyChangedEventArgs<T> RoutedPropertyChangedEventArgs<T> RoutedPropertyChangedEventArgs<T>

The event data. Specific event definitions will constrain RoutedPropertyChangedEventArgs<T> to a type, with the type parameter of the constraint matching the type parameter constraint of a delegate implementation.



The following example defines and attaches a handler method for the ValueChanged event.

The handler is based on RoutedPropertyChangedEventHandler<T>, and is defined in the second segment of the code example, with the type parameter of the generic constrained to Double.

Slider childrenCountSlider = (Slider)LogicalTreeHelper.FindLogicalNode(myWindow, "ChildrenCountSlider");
childrenCountSlider.ValueChanged += new RoutedPropertyChangedEventHandler<double>(OnChildrenCountChanged);
Dim childrenCountSlider As Slider = CType(LogicalTreeHelper.FindLogicalNode(myWindow, "ChildrenCountSlider"), Slider)
AddHandler childrenCountSlider.ValueChanged, AddressOf OnChildrenCountChanged
private void OnChildrenCountChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
    int childrenCount = (int)Math.Floor(e.NewValue + 0.5);

    //  Update the children count...
    AutoIndexingGrid g = (AutoIndexingGrid)LogicalTreeHelper.FindLogicalNode(myWindow, "TargetGrid");
    while (g.Children.Count < childrenCount)
        Control c = new Control();
        c.Style = (Style)c.FindResource("ImageWithBorder");
    while (g.Children.Count > childrenCount)
        g.Children.Remove(g.Children[g.Children.Count - 1]);

    //  Update TextBlock element displaying the count...
    TextBlock t = (TextBlock)LogicalTreeHelper.FindLogicalNode(myWindow, "ChildrenCountDisplay");
    t.Text = childrenCount.ToString();
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()
        c.Style = CType(c.FindResource("ImageWithBorder"), Style)
    Do While g.Children.Count > childrenCount
        g.Children.Remove(g.Children(g.Children.Count - 1))

    '  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.


Examples of events that use type-constrained delegates based on RoutedPropertyChangedEventHandler<T> include TreeView.SelectedItemChanged and RangeBase.ValueChanged.

Extension Methods

GetMethodInfo(Delegate) GetMethodInfo(Delegate) GetMethodInfo(Delegate) GetMethodInfo(Delegate)

Gets an object that represents the method represented by the specified delegate.

Applies to

See also