Unity可拖动UI

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.EventSystems;

public class DragPanel:MonoBehaviour,IDragHandler,IPointerDownHandler
{
   private RectTransform panel;
   private Canvas canvas;
   
   void Start()
   {
           panel = this.GetComponent<RectTransform>();
           canvas = GameObject.Find("Canvas").GetComponent<Canvas>();
   }

    public void OnDrag(PointerEventData eventData)
    {
        panel.anchoredPosition+=eventData.delta/canvas.scaleFactor;
    }

    public void OnPointerDown(PointerEventData eventData)
    {
        panel.SetAsLastSibling();//设置最高层
    }
}