Unity UI簡易拖曳跟隨

EventTriggerListener

using UnityEngine;
using System.Collections;
using UnityEngine.EventSystems;
public class EventTriggerListener : UnityEngine.EventSystems.EventTrigger
{
    public delegate void VoidDelegate(GameObject go);
    public delegate void VoidDelegatePointer(GameObject go, Vector2 pos);

    public VoidDelegate onClick;
    public VoidDelegate onDown;
    public VoidDelegate onEnter;
    public VoidDelegate onExit;
    public VoidDelegate onUp;
    public VoidDelegate onSelect;
    public VoidDelegate onUpdateSelect;

    public VoidDelegatePointer onBeginDrag;
    public VoidDelegatePointer onDrag;
    public VoidDelegatePointer onEndDrag;

    static public EventTriggerListener Get(GameObject go)
    {
        EventTriggerListener listener = go.GetComponent<EventTriggerListener>();
        if (listener == null) listener = go.AddComponent<EventTriggerListener>();
        return listener;
    }
    public override void OnPointerClick(PointerEventData eventData)
    {
        if (onClick != null) onClick(gameObject);
    }
    public override void OnPointerDown(PointerEventData eventData)
    {
        if (onDown != null) onDown(gameObject);
    }
    public override void OnPointerEnter(PointerEventData eventData)
    {
        if (onEnter != null) onEnter(gameObject);
    }
    public override void OnPointerExit(PointerEventData eventData)
    {
        if (onExit != null) onExit(gameObject);
    }
    public override void OnPointerUp(PointerEventData eventData)
    {
        if (onUp != null) onUp(gameObject);
    }
    public override void OnSelect(BaseEventData eventData)
    {
        if (onSelect != null) onSelect(gameObject);
    }
    public override void OnUpdateSelected(BaseEventData eventData)
    {
        if (onUpdateSelect != null) onUpdateSelect(gameObject);
    }
    public override void OnBeginDrag(PointerEventData eventData)
    {
        if (onBeginDrag != null) onBeginDrag(gameObject, eventData.position);
    }
    public override void OnDrag(PointerEventData eventData)
    {
        if (onDrag != null) onDrag(gameObject, eventData.position);
    }
    public override void OnEndDrag(PointerEventData eventData)
    {
        if (onEndDrag != null) onEndDrag(gameObject, eventData.position);
    }
}

TestEvent

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

public class TestEvent : MonoBehaviour {
	void Start () {
        EventTriggerListener.Get(gameObject).onBeginDrag = OnBeginDrag;
        EventTriggerListener.Get(gameObject).onDrag = OnDrag;
        EventTriggerListener.Get(gameObject).onEndDrag = OnEndDrag;
    }
    void OnBeginDrag(GameObject go, Vector2 pos) {
        Debug.Log("OnBeginDrag" + pos);
	}
    void OnDrag(GameObject go, Vector2 pos)
    {
        Debug.Log("OnBegin" + pos);
        go.transform.position = pos;
    }
    void OnEndDrag(GameObject go, Vector2 pos)
    {
        Debug.Log("OnBeginEnd" + pos);
    }
}