C# WPF -如何使用行为通过箭头键移动对象？

using System.Windows;
using System.Windows.Input;
using System.Windows.Interactivity;

public class ArrowKeyBehavior : Behavior<UIElement>
{
    protected override void OnAttached()
    {
        AssociatedObject.KeyDown += AssociatedObject_KeyDown;
    }

    protected override void OnDetaching()
    {
        AssociatedObject.KeyDown -= AssociatedObject_KeyDown;
    }

    private void AssociatedObject_KeyDown(object sender, KeyEventArgs e)
    {
        double stepSize = 10; // 移动步长

        switch (e.Key)
        {
            case Key.Left:
                Canvas.SetLeft(AssociatedObject, Canvas.GetLeft(AssociatedObject) - stepSize);
                break;
            case Key.Right:
                Canvas.SetLeft(AssociatedObject, Canvas.GetLeft(AssociatedObject) + stepSize);
                break;
            case Key.Up:
                Canvas.SetTop(AssociatedObject, Canvas.GetTop(AssociatedObject) - stepSize);
                break;
            case Key.Down:
                Canvas.SetTop(AssociatedObject, Canvas.GetTop(AssociatedObject) + stepSize);
                break;
        }
    }
}

<Canvas>
    <Rectangle Width="50" Height="50" Fill="Red">
        <i:Interaction.Behaviors>
            <local:ArrowKeyBehavior />
        </i:Interaction.Behaviors>
    </Rectangle>
</Canvas>