Unity 上下拖动图片

using UnityEngine;
using UnityEngine.EventSystems;
using DG.Tweening;
public class MoveObj : MonoBehaviour, IDragHandler, IPointerDownHandler {

    //private Vector2 offsetPos;  //临时记录点击点与UI的相对位置


    //public void OnPointerDown(PointerEventData eventData)
    //{
    //    offsetPos = eventData.position - (Vector2)transform.position;
    //}

    //public void OnDrag(PointerEventData eventData) {
    //    transform.position = eventData.position - offsetPos;
    //}

    private Vector2 offsetPos;  //临时记录点击点与UI的相对位置

    private float posX;
    private float posY;



    public void OnPointerDown(PointerEventData eventData) {
        offsetPos = eventData.position - (Vector2)transform.position;
        posX = transform.position.x;
    }

    public void OnDrag(PointerEventData eventData) {

        posY = eventData.position.y - offsetPos.y;
        Vector2 pos = transform.position;
        pos.y = posY;
        //  transform.position = pos;
        transform.DOMoveY(posY, 0.2f);
    }
}