【转载】Unity3d使用UGUI实现长按功能
UGUI的Button组件只有OnClick事件的监听，要实现长按功能，要监听按下事件和抬起事件，所以要使用到EventTrigger组件中的OnPointerDown和OnPointerUp来监听。**代码：**
```
using UnityEngine;
using System.Collections;
using UnityEngine.EventSystems;
public class EventTriggerListener : UnityEngine.EventSystems.EventTrigger
{
public delegate void VoidDelegate(GameObject go);
public delegate void BoolDelegate(GameObject go, bool state);
public delegate void FloatDelegate(GameObject go, float delta);
public delegate void VectorDelegate(GameObject go, Vector2 delta);
public delegate void ObjectDelegate(GameObject go, GameObject obj);
public delegate void KeyCodeDelegate(GameObject go, KeyCode key);
public VoidDelegate onClick;
public VoidDelegate onDown;
public VoidDelegate onEnter;
public VoidDelegate onExit;
public VoidDelegate onUp;
public VoidDelegate onSelect;
public VoidDelegate onUpdateSelect;
static public EventTriggerListener Get(GameObject go)
{
EventTriggerListener listener = go.GetComponent<EventTriggerListener>();
if (listener == null) listener = go.AddComponent<EventTriggerListener>();
return listener;
}
static public EventTriggerListener Get(Transform transform)
{
EventTriggerListener listener = transform.GetComponent<EventTriggerListener>();
if (listener == null) listener = transform.gameObject.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);
}
}
```
使用EventTriggerListener的Get方法就可以了，和NGUI的UIEventListener一样。
例如：
```
EventTriggerListener.Get(gameObject).onDown += OnClickDown;
EventTriggerListener.Get(gameObject).onUp += OnClickUp;
```
然后在场景中添加一个按钮
然后再按钮上挂一个事件监听的脚本，譬如我要做一个类似技能CD冷却的效果，点击开始遮罩，松开恢复原状。
脚本如下：
```
using UnityEngine;
using System.Collections;
using UnityEngine.UI;
public class EventTest : MonoBehaviour {
private bool isUp;
private Image img;
void Start () {
/*EventTriggerListener.Get(gameObject).onDown += (go) => { Debug.Log("按下！"); };
EventTriggerListener.Get(gameObject).onUp += (go) => { Debug.Log("抬起！"); };
EventTriggerListener.Get(gameObject).onSelect += (go) => { Debug.Log("选中！"); };
EventTriggerListener.Get(gameObject).onEnter += (go) => { Debug.Log("进入！"); };
EventTriggerListener.Get(gameObject).onExit += (go) => { Debug.Log("退出！"); };
* */
img = transform.Find("Image").GetComponent<Image>();
EventTriggerListener.Get(gameObject).onDown += OnClickDown;
EventTriggerListener.Get(gameObject).onUp += OnClickUp;
}
void OnClickDown(GameObject go)
{
isUp = false;
StartCoroutine(grow());
}
void OnClickUp(GameObject go)
{
isUp = true;
img.fillAmount = 0f;
}
private IEnumerator grow()
{
while (true)
{
if (isUp)
{
break;
}
img.fillAmount += 0.5f * Time.deltaTime;
if (img.fillAmount == 0)
{
break;
}
yield return null;
}
}
}
```
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