private void HandleShapeChanged(object sender, ShapeEventArgs e) { Shape s = (Shape)sender; Console.WriteLine("Received event . Shape area is noew {0}", e.NewArea); // 重新Draw s.Draw(); }
protected override void OnShapeChanged(ShapeEventArgs e) { base.OnShapeChanged(e); }
protected virtual void OnShapeChanged(ShapeEventArgs e) { ShapeChanged?.Invoke(this, e); // 当shape改变的时候 , 就调用事件 , 通知别人. }