/// <inheritdoc/>
protected override void OnAttached()
{
if (EventName == null)
{
throw new ArgumentException($"The EventName property must be set on behavior '{GetType().FullName}'.");
}
var eventOwnerType = EventOwnerType ?? AssociatedObject.GetType();
var uiElement = AssociatedObject as UIElement;
var routedEvents = EventManager.GetRoutedEvents().Where(x => x.Name == EventName && x.OwnerType.IsAssignableFrom(eventOwnerType)).ToArray();
if (uiElement != null && routedEvents.Length > 0)
{
if (routedEvents.Length > 1)
{
throw new NotImplementedException("TODO: several events found, find a way to decide the most relevant one.");
}
routedEvent = routedEvents.First();
uiElement.AddHandler(routedEvent, routedEventHandler);
}
else
{
var eventInfo = AssociatedObject.GetType().GetEvent(EventName);
if (eventInfo == null)
{
throw new InvalidOperationException($"Impossible to find a valid event named '{EventName}'.");
}
eventHandler = AnonymousEventHandler.RegisterEventHandler(eventInfo, AssociatedObject, OnEvent);
}
}
/// <inheritdoc/>
protected override void OnDetaching()
{
if (routedEvent != null)
{
AssociatedObject.RemoveHandler(routedEvent, routedEventHandler);
routedEvent = null;
}
else if (eventHandler != null)
{
AnonymousEventHandler.UnregisterEventHandler(eventHandler);
eventHandler = null;
}
}
