public void AddEventListener(string eventType, TargetEventHandler handler)
{
if (eventType == null)
{
return;
}
if (handler == null)
{
return;
}
var sendListen = false;
List <TargetEventHandler> handlers;
lock (eventListeners) {
if (!eventListeners.TryGetValue(eventType, out handlers))
{
handlers = new List <TargetEventHandler> ();
eventListeners[eventType] = handlers;
sendListen = true;
}
handlers.Add(handler);
}
if (sendListen)
{
Send(new Message {
MessageType = MessageType.Listen,
TargetId = Id,
Key = eventType,
});
}
}
// Wrap event invocations inside a protected virtual method
protected virtual void OnTargetEventHandler(TargetEventArgs e)
{
// Make a temporary copy of the event to avoid possibility of
// a race condition if the last subscriber unsubscribes
// immediately after the null check and before the event is raised.
TargetEventHandler?.Invoke(this, e);
}
protected virtual NativeGestureRecognizer GetNativeRecognizer(IGestureRecognizer recognizer)
{
if (recognizer == null)
{
return(null);
}
var weakRecognizer = new WeakReference(recognizer);
var weakEventTracker = new WeakReference(this);
var tapRecognizer = recognizer as TapGestureRecognizer;
if (tapRecognizer != null && tapRecognizer.NumberOfTapsRequired == 1)
{
var returnAction = new TargetEventHandler((s, e) =>
{
var tapGestureRecognizer = weakRecognizer.Target as TapGestureRecognizer;
var eventTracker = weakEventTracker.Target as EventTracker;
var view = eventTracker?._renderer?.Element as View;
if (tapGestureRecognizer != null && view != null)
{
tapGestureRecognizer.SendTapped(view);
}
});
var uiRecognizer = new NativeGestureRecognizer
{
EventType = "click",
Handler = returnAction,
};
return(uiRecognizer);
}
if (tapRecognizer != null && tapRecognizer.NumberOfTapsRequired == 2)
{
var returnAction = new TargetEventHandler((s, e) =>
{
var tapGestureRecognizer = weakRecognizer.Target as TapGestureRecognizer;
var eventTracker = weakEventTracker.Target as EventTracker;
var view = eventTracker?._renderer?.Element as View;
if (tapGestureRecognizer != null && view != null)
{
tapGestureRecognizer.SendTapped(view);
}
});
var uiRecognizer = new NativeGestureRecognizer
{
EventType = "dblclick",
Handler = returnAction,
};
return(uiRecognizer);
}
return(null);
}
public void RemoveEventListener(string eventType, TargetEventHandler handler)
{
if (eventType == null)
{
return;
}
if (handler == null)
{
return;
}
List <TargetEventHandler> handlers;
lock (eventListeners) {
if (eventListeners.TryGetValue(eventType, out handlers))
{
handlers.Remove(handler);
}
}
}
