Custom attached events in WPF

Question

I might be getting the terminology wrong here, but I think I'm trying to create an attached event.

In the Surface SDK, you can do things like:

<Grid Background="{StaticResource WindowBackground}" x:Name="Foo" s:SurfaceFrameworkElement.ContactChanged="Foo_ContactChanged"/>

I want to create a custom event for which a handler can be added in XAML in the same way, but I'm having trouble.

I can create a custom routed event, but the XAML intellisense doesn't see it and the event handler isn't added if I just type it in regularly. Here is my event definition:

public static class TagRectEvents
{
    public static readonly RoutedEvent TagRectEnterEvent = EventManager.RegisterRoutedEvent(
        "TagRectEnter", RoutingStrategy.Bubble, typeof( RoutedEventHandler ), typeof( TagRectEvents ) );

    public static void AddTagRectEnterHandler( DependencyObject d, RoutedEventHandler handler )
    {
        UIElement element = d as UIElement;
        if ( element == null )
        {
            return;
        }
        element.AddHandler( TagRectEvents.TagRectEnterEvent, handler );
    }

    public static void RemoveTagRectEnterHandler( DependencyObject d, RoutedEventHandler handler )
    {
        UIElement element = d as UIElement;
        if ( element == null )
        {
            return;
        }
        element.RemoveHandler( TagRectEvents.TagRectEnterEvent, handler );
    }
}

Am I just going about it all wrong? All of the "attached behavior" examples I see are more about adding an attached property, and then doing things with elements that set that property.

Answer 1

You must either be not mapping the namespace, and/or attaching event like local:TagRectEvents.TagRectEnterEvent . You have to use TagRectEnter , and not TagRectEnterEvent .

Namespace mapping :

 xmlns:local="clr-namespace:WpfInfrastructure.WpfAttachedEvents"

Usage :

<Button Content="Press" local:TagRectEvents.TagRectEnter="MyHandler" Margin="25,43,36,161" />

Handler :

    public void MyHandler(object sender, RoutedEventArgs e)
    {
        System.Diagnostics.Debug.WriteLine("Hurray!");
    }

I used your code, it works correctly here.

Answer 2

In order to get the attached event to show up in Intellisense, it has to be in a class that resides in a satellite assembly -- or .dll library. The easiest way to add a library is add a "WPF Custom Control Library" project to your solution. Using a Wpf control library just ensures that all the typical References will be added automatically (which they won't with a C# class library.) You can delete the CustomControl1.cs just as long as you delete its associated Style in Themes/Generic.xaml.