It is possible to pass data to EventArgs without creating derived class?

Question

I am a bit confused. I know I can create class derived from EventArgs in order to have custom event data. But can I employ the base class EventArgs somehow? Like the mouse butto

Answer 1

You can use the EventArgs class through the Generic Types approach. In this sample, i will use the Rect class with as return type:

public EventHandler SizeRectChanged;

Raising the event:

if(SizeRectChanged != null){
   Rect r = new Rect(0,0,0,0);
   SizeRectChanged(this,r);
}

Listening the event:

anyElement.SizeRectChanged += OnSizeRectChanged;

public void OnSizeRectChanged(object sender, Rect e){
    //TODO abything using the Rect class
    e.Left = e.Top = e.Width = e.Height = 50;
}

So, don't need to create new events classes or delegates, simply create a EventHandler passing the specific type T.