/// <summary>
/// Gets the existing <see cref="InterfaceEventListener"/> for the given <see cref="Action"/>.
/// </summary>
/// <param name="dispatcher"></param>
/// <param name="eventType"></param>
/// <param name="capture"></param>
/// <param name="action"></param>
/// <returns></returns>
public static InterfaceEventListener GetListener(EventTarget dispatcher, string eventType, bool capture, Action<Event> action)
{
Contract.Requires<ArgumentNullException>(dispatcher != null);
Contract.Requires<ArgumentNullException>(!string.IsNullOrWhiteSpace(eventType));
Contract.Requires<ArgumentNullException>(action != null);
Contract.Requires<ArgumentException>(action.Target != null, "Action must have target.");
Contract.Requires<ArgumentException>(action.Method != null, "Action must have method.");
Contract.Requires<ArgumentException>(action.Target is ElementExtension, "Action.Target must be a ElementExtension.");
Contract.Requires<ArgumentException>(IsValidMethodInfo(action.Method));
var handler = action.Target;
var method = action.Method;
return GetListener(dispatcher, eventType, capture, ((ElementExtension)handler).Element, handler.GetType(), method);
}
/// <summary>
/// Gets the existing <see cref="InterfaceEventListener"/> registered on the target.
/// </summary>
/// <param name="dispatcher"></param>
/// <param name="eventType"></param>
/// <param name="capture"></param>
/// <param name="handler"></param>
/// <param name="interfaceType"></param>
/// <param name="methodInfo"></param>
/// <returns></returns>
public static InterfaceEventListener GetListener(EventTarget dispatcher, string eventType, bool capture, XObject handler, Type interfaceType, MethodInfo methodInfo)
{
Contract.Requires<ArgumentNullException>(dispatcher != null);
Contract.Requires<ArgumentNullException>(!string.IsNullOrWhiteSpace(eventType));
Contract.Requires<ArgumentNullException>(handler != null);
Contract.Requires<ArgumentNullException>(interfaceType != null);
Contract.Requires<ArgumentNullException>(methodInfo != null);
Contract.Requires<ArgumentException>(IsValidMethodInfo(methodInfo));
var host = handler.Exports().GetExportedValue<Func<Document>>()();
if (host == null)
throw new InvalidOperationException();
// find existing listener
var listener = Enumerable.Empty<EventListenerRegistration>()
.Concat(dispatcher.GetRegistrations())
.OfType<InterfaceEventListener>()
.Where(i => i.GetHandler(host) == handler)
.Where(i => i.InterfaceType == interfaceType)
.FirstOrDefault();
return listener;
}