Unity,UI拖拽（跟随手指移动）

public class UIDrag : MonoBehaviour, IPointerDownHandler, IDragHandler, IEndDragHandler {

    #region 字段     public RectTransform canvas;     private RectTransform imgRect;     Vector2 offest = new Vector2();     #endregion

    private void Start()     {         imgRect = this.GetComponent();         canvas = this.transform.parent.GetComponent();     }

    #region  接口     public void OnDrag(PointerEventData eventData)     {         Vector2 mouseDrag = eventData.position;         Vector2 uguiPos = new Vector2();

        //RectTransformUtility.ScreenPointToLocalPointInRectangle() 把屏幕坐标转换成UI坐标         //canvas 为当前物体的父物体的RectTransform         bool isRect = RectTransformUtility.ScreenPointToLocalPointInRectangle(canvas,mouseDrag,eventData.enterEventCamera,out uguiPos);         if (isRect)         {             imgRect.anchoredPosition = offest + uguiPos;         }     }

    public void OnEndDrag(PointerEventData eventData)     {         offest = Vector2.zero;     }

    public void OnPointerDown(PointerEventData eventData)     {         Debug.Log("按下");         Vector2 mouseDown = eventData.position;   //鼠标按下时的屏幕坐标         Vector2 mouseUguiPos = new Vector2();   //返回的UGUI坐标         bool isRect = RectTransformUtility.ScreenPointToLocalPointInRectangle(canvas,mouseDown,eventData.enterEventCamera,out mouseUguiPos);         if (isRect)         {             offest = imgRect.anchoredPosition - mouseUguiPos;     //计算点击在UI上但是没点击在UI正中心             Debug.Log(offest);         }     }

    #endregion }