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RoutingStrategy Enumeration

Indicates the routing strategy of a routed event.

Namespace:  System.Windows
Assembly:  PresentationCore (in PresentationCore.dll)

public enum RoutingStrategy
<object property="enumerationMemberName" .../>

Member nameDescription
TunnelThe routed event uses a tunneling strategy, where the event instance routes downwards through the tree, from root to source element.
BubbleThe routed event uses a bubbling strategy, where the event instance routes upwards through the tree, from event source to root.
DirectThe routed event does not route through an element tree, but does support other routed event capabilities such as class handling, EventTrigger or EventSetter.

Routing strategy for each routed event must be only one of these values. However, input events often exist in pairs on base classes, where one event is the bubbling version and one event is the tunneling version. For input events uniquely, the tunneling and bubbling versions have shared arguments and are raised in succession in response to the input device condition that raises the events.

For your custom event to support event routing, you need to register a RoutedEvent using the RegisterRoutedEvent method. This example demonstrates the basics of creating a custom routed event.

As shown in the following example, you first register a RoutedEvent using the RegisterRoutedEvent method. By convention, the RoutedEvent static field name should end with the suffix Event. In this example, the name of the event is Tap and the routing strategy of the event is Bubble. After the registration call, you can provide add-and-remove common language runtime (CLR) event accessors for the event.

Note that even though the event is raised through the OnTap virtual method in this particular example, how you raise your event or how your event responds to changes depends on your needs.

Note also that this example basically implements an entire subclass of Button; that subclass is built as a separate assembly and then instantiated as a custom class on a separate Extensible Application Markup Language (XAML) page. This is to illustrate the concept that subclassed controls can be inserted into trees composed of other controls, and that in this situation, custom events on these controls have the very same event routing capabilities as any native Windows Presentation Foundation (WPF) element does.

public class MyButtonSimple: Button
{
    // Create a custom routed event by first registering a RoutedEventID 
    // This event uses the bubbling routing strategy 
    public static readonly RoutedEvent TapEvent = EventManager.RegisterRoutedEvent(
        "Tap", RoutingStrategy.Bubble, typeof(RoutedEventHandler), typeof(MyButtonSimple));

    // Provide CLR accessors for the event 
    public event RoutedEventHandler Tap
    {
            add { AddHandler(TapEvent, value); } 
            remove { RemoveHandler(TapEvent, value); }
    }

    // This method raises the Tap event 
    void RaiseTapEvent()
    {
            RoutedEventArgs newEventArgs = new RoutedEventArgs(MyButtonSimple.TapEvent);
            RaiseEvent(newEventArgs);
    }
    // For demonstration purposes we raise the event when the MyButtonSimple is clicked 
    protected override void OnClick()
    {
        RaiseTapEvent();
    }

}
<Window  
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:custom="clr-namespace:SDKSample;assembly=SDKSampleLibrary"
    x:Class="SDKSample.RoutedEventCustomApp"

    >
    <Window.Resources>
      <Style TargetType="{x:Type custom:MyButtonSimple}">
        <Setter Property="Height" Value="20"/>
        <Setter Property="Width" Value="250"/>
        <Setter Property="HorizontalAlignment" Value="Left"/>
        <Setter Property="Background" Value="#808080"/>
      </Style>
    </Window.Resources>
    <StackPanel Background="LightGray">
	    <custom:MyButtonSimple Name="mybtnsimple" Tap="TapHandler">Click to see Tap custom event work</custom:MyButtonSimple>
    </StackPanel>
</Window>

Tunneling events are created the same way, but with RoutingStrategy set to Tunnel in the registration call. By convention, tunneling events in WPF are prefixed with the word "Preview".

To view the complete sample, including the implementation of the actual "Tap" event handler, see Custom Routed Events Sample. To see an example of how bubbling events work, see How to: Handle a Routed Event.

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0

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