uGUI长按事件

突然发现uGUI没有给出可以直接用的长按事件。。。

上个没有注释的代码，代码说明一切。

using UnityEngine;
using System.Collections;
using UnityEngine.Events;
using UnityEngine.EventSystems;

public class UILongPressEvent : MonoBehaviour,IPointerDownHandler,IPointerExitHandler,IPointerUpHandler
{
    [SerializeField]
    UnityEvent m_onLongPress = new UnityEvent();

    float interval = 0.1f;
    float longPressDelay = 0.5f;

    private bool isTouchDown = false;
    private bool isLongpress = false;
    private float touchBegin = 0;
    private float lastInvokeTime = 0;

    // Update is called once per frame
    void Update () 
    {
        if (isTouchDown)
        {
            if (isLongpress)
            {
                if (Time.time - lastInvokeTime > interval)
                {
                    m_onLongPress.Invoke();
                    lastInvokeTime = Time.time;
                }
            }
            else
            {
                if (Time.time - touchBegin > longPressDelay)
                {
                    isLongpress = true;
                }
            }
        }
    }

    public void OnPointerDown(PointerEventData eventData)
    {
        touchBegin = Time.time;
        isTouchDown = true;
    }

    public void OnPointerExit(PointerEventData eventData)
    {
        isTouchDown = false;
        isLongpress = false;
    }

    public void OnPointerUp(PointerEventData eventData)
    {
        isTouchDown = false;
        isLongpress = false;
    }
}