【UGUI】UGUI 拖拽图片

首先看一下效果

附上代码

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

public class UIDrag : UIBase, IBeginDragHandler, IDragHandler, IEndDragHandler, IPointerClickHandler
{

    private bool isDrag;
    private RectTransform rect;
    private Vector2 tempPos;
    private Vector3 offset = Vector3.zero;

    //private static int index = 0;
    public void OnBeginDrag(PointerEventData eventData)
    {
        SetIndex();
        isDrag = false;
        SetDragObjPostion(eventData);
    }

    public void OnDrag(PointerEventData eventData)
    {
        isDrag = true;
        SetDragObjPostion(eventData);
    }

    void SetDragObjPostion(PointerEventData eventData)
    {
        RectTransform rect = this.GetComponent<RectTransform>();
        Vector3 mouseWorldPosition;

        //判断是否点到UI图片上的时候
        if (RectTransformUtility.ScreenPointToWorldPointInRectangle(rect, eventData.position, eventData.pressEventCamera,
            out mouseWorldPosition))
        {
            if (isDrag)
            {
                rect.position = mouseWorldPosition + offset;
            }
            else
            {
                //计算偏移量
                offset = rect.position - mouseWorldPosition;
            }
        }
    }

    void IEndDragHandler.OnEndDrag(PointerEventData eventData)
    {
        //isDrag = false;
    }

    public void SetIndex()
    {
        gameObject.transform.SetAsLastSibling();
    }

    public void OnPointerClick(PointerEventData eventData)
    {
        SetIndex();
    }
}