//--------------------------------------------------------
//    [Author]:           玩个游戏
//    [  Date ]:           Saturday, March 16, 2019
//--------------------------------------------------------
using System;
using UnityEngine;
using UnityEngine.Events;
using UnityEngine.EventSystems;

public class GestureCatcher : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler
{
    Action<Vector2> m_OnDrag;
    Vector2 prePosition = Vector2.zero;

    public void SetDragListener(Action<Vector2> callBack)
    {
        m_OnDrag = callBack;
    }

    public void RemoveListener()
    {
        m_OnDrag = null;
    }

    public void OnBeginDrag(PointerEventData eventData)
    {
        prePosition = eventData.position;
    }

    public void OnDrag(PointerEventData eventData)
    {
        var deltaPosition = eventData.position - prePosition;
        m_OnDrag.Invoke(deltaPosition);
        prePosition = eventData.position;
    }

    public void OnEndDrag(PointerEventData eventData)
    {
        prePosition = eventData.position;
    }

}