动态添加的控件，出现时候添加动画,该如何处理

 Floor floor = new Floor();
                 
                floor.Height = 10;
                floor.Width = 10;
                double delt = 2 * i * Math.PI / buildings.Count;
                this.LayoutRoot.Children.Add(floor);
                double X = CenterX - floor.Width / 2 + 50 * Math.Cos(delt);
                double Y = CenterY - floor.Height / 2 + 50 * Math.Sin(delt);
                Canvas.SetLeft(floor, X);
                Canvas.SetTop(floor, Y);

Storyboard storyboard = new Storyboard();
                //storyboard.Duration = new Duration(TimeSpan.FromSeconds(0.5));
                DoubleAnimation slideOut = new DoubleAnimation();
                slideOut.SetValue(Storyboard.TargetNameProperty, "floor");
                slideOut.SetValue(Storyboard.TargetPropertyProperty, new PropertyPath("(UIElement.Opacity)"));
                
                slideOut.Duration = new Duration(TimeSpan.FromSeconds(0.5));
                slideOut.To = 0;
                slideOut.From = 1;
                storyboard.Children.Add(slideOut);
                LayoutRoot.Resources.Add("Storyboard", storyboard);
                storyboard.Begin();