public class ScrollViewListener : MonoBehaviour, IDragHandler, IBeginDragHandler, IEndDragHandler
  {
 //滑动方向
    public enum MoveDirection
    {
      None = 0,
      Left,
      Right,
    }
    public float SingleItemWidth;//单个滑动页的宽度
    public RectTransform content;//当前ScrollView的Content
    public float DragMinValue = 5f;//拖动过程中允许的最小的拖拽值，低于此值就不算拖拽，不执行翻页事件
    private MoveDirection direction = MoveDirection.None;
    private int CurIndex = 0;//当前页码
    private int MaxIndex = 0;//最大页码
    public bool canMove = true;//是否能移动
    private Vector3 originalPos;
    private float maxDeltaX = 0f;//取整个拖动过程中的最大值
    public Action OnPageChange;//对外提供页码修改的回调
 
    /// 

    /// 滑到下一页
    /// 
    private void MoveToNext()
    {      
      if (direction == MoveDirection.Left)
      {
        if (CurIndex < MaxIndex)
        {          
          CurIndex++;
          canMove = false;
          content.DOLocalMoveX(content.localPosition.x - SingleItemWidth, 1f).OnComplete(() =>
          {
            if (null != OnPageChange)
            {
              OnPageChange(CurIndex);
            }
            canMove = true;
          });
        }
      }
      else if (direction == MoveDirection.Right)
      {
        if (CurIndex > 0)
        {
          CurIndex--;
          canMove = false;
          content.DOLocalMoveX(content.localPosition.x + SingleItemWidth, 1f).OnComplete(() =>
          {
            if (null != OnPageChange)
            {
              OnPageChange(CurIndex);
            }
            canMove = true;
          });
        }
      }
    }
 
    /// 

    /// 设置当前滑动列表的页数的最大值
    /// 
    /// 
    public void SetMaxIndex(int max)
    {
      MaxIndex = max - 1;//最大下标值为页数减1
    }
 
    /// 

    /// 设置当前页
    /// 
    /// 
    public void SetCurIndex(int index)
    {
      CurIndex = index;
      float x = content.localPosition.x - SingleItemWidth * CurIndex;
      content.localPosition = new Vector3(x, content.localPosition.y, content.localPosition.z);
    }
 
    public void ResetPosition()
    {
      content.localPosition = originalPos;
    }
 
    private void Awake()
 {
      CurIndex = 0;
      originalPos = content.localPosition;
    }
 
    public void OnDrag(PointerEventData eventData)
    {
      if (Mathf.Abs(eventData.delta.x) > maxDeltaX)
      {
        maxDeltaX = Mathf.Abs(eventData.delta.x);
      }
    }
 
    public void OnBeginDrag(PointerEventData eventData)
    {
      if (eventData.delta.x > 0)
      {
        direction = MoveDirection.Right;
      }
      else if (eventData.delta.x < 0)
      {
        direction = MoveDirection.Left;
      }
      else
      {
        direction = MoveDirection.None;
      }
      if (Mathf.Abs(eventData.delta.x) > maxDeltaX)
      {
        maxDeltaX = Mathf.Abs(eventData.delta.x);
      }
    }
 
    public void OnEndDrag(PointerEventData eventData)
    {
      if (Mathf.Abs(eventData.delta.x) > maxDeltaX)
      {
        maxDeltaX = Mathf.Abs(eventData.delta.x);
      }
      if (maxDeltaX > DragMinValue)
      {
        //计算下一页的目的点 然后移动
        if (canMove)
        {
          MoveToNext();
        }        
      }
      maxDeltaX = 0f;
    }
  }