EventTrigger

我们知道Button可以添加点击监听，Slider可以滑动，假如我们想给Image添加点击监听，或者更多的监听事件呢，比如选中、鼠标移入、拖动。我们可以用到EventTrigger。EventTrigger里继承了很多接口，正好可以用来封装

public class EventTriggerTest : EventTrigger {

    public override void OnPointerClick (PointerEventData eventData) {
        Debug.Log ("OnPointerClick");
    }

    public override void OnPointerEnter (PointerEventData eventData) {
        Debug.Log ("OnPointerEnter");
    }

    public override void OnPointerExit (PointerEventData eventData) {
        Debug.Log ("OnPointerExit");
    }

}

这里重写了EventTrigger里的3个方法，分别是点击、鼠标移入、鼠标移出，我们把它挂载在一个Image上，运行，可以看到，根据操作，确实可以执行对应的方法。

image.png

EventListener

要是有很多控件都需要绑定，那就需要在里面都挂上这个脚本，每个脚本都在对应的方法下重写内容，这样显得过于麻烦，我们可以就写一个脚本，继承自EventTrigger，通过委托的形式，触发EventTrigger下的事件是就执行委托的方法，具体的方法内容在各自的脚本里去实现就可以了。

public class UIEventListener : EventTrigger {
    public delegate void VoidDelegate (GameObject go);
    public delegate void BoolDelegate (GameObject go, bool isValue);
    public delegate void FloatDelegate (GameObject go, float fValue);
    public delegate void IntDelegate (GameObject go, int iIndex);
    public delegate void StringDelegate (GameObject go, string strValue);

    public VoidDelegate onSubmit;
    public VoidDelegate onClick;
    public BoolDelegate onHover;
    public BoolDelegate onToggleChanged;
    public FloatDelegate onSliderChanged;
    public FloatDelegate onScrollbarChanged;
    public IntDelegate onDrapDownChanged;
    public StringDelegate onInputFieldChanged;

    public override void OnSubmit (BaseEventData eventData) {  //提交
        if (onSubmit != null)
            onSubmit (gameObject);
    }
    public override void OnPointerEnter (PointerEventData eventData) { //鼠标移入
        if (onHover != null)
            onHover (gameObject, true);
    }
    public override void OnPointerClick (PointerEventData eventData) { //点击
        if (onClick != null)
            onClick (gameObject);
        if (onToggleChanged != null)
            onToggleChanged (gameObject, gameObject.GetComponent<Toggle> ().isOn);

    }
    public override void OnPointerExit (PointerEventData eventData) { //鼠标移出
        if (onHover != null)
            onHover (gameObject, false);
    }
    public override void OnDrag (PointerEventData eventData) { //拖动
        if (onSliderChanged != null)
            onSliderChanged (gameObject, gameObject.GetComponent<Slider> ().value);
        if (onScrollbarChanged != null)
            onScrollbarChanged (gameObject, gameObject.GetComponent<Scrollbar> ().value);

    }
    public override void OnSelect (BaseEventData eventData) { //选中
        if (onDrapDownChanged != null)
            onDrapDownChanged (gameObject, gameObject.GetComponent<Dropdown> ().value);
    }
    public override void OnUpdateSelected (BaseEventData eventData) { //选中、每帧更新
        if (onInputFieldChanged != null)
            onInputFieldChanged (gameObject, gameObject.GetComponent<InputField> ().text);
    }
    public override void OnDeselect (BaseEventData eventData) { //不选中
        if (onInputFieldChanged != null)
            onInputFieldChanged (gameObject, gameObject.GetComponent<InputField> ().text);
    }

    public static UIEventListener Get (GameObject go) {
        UIEventListener listener = go.GetComponent<UIEventListener> ();
        if (listener == null) listener = go.AddComponent<UIEventListener> ();
        return listener;
    }
}

试一下把，我们还是实现上面的功能，现在不用手动去挂载专门的脚本，只要在Image的执行脚本里添加就可以了，运行后程序会自动添加上UIEventListener.cs。

public class Test1 : MonoBehaviour {

    // Use this for initialization
    void Start () {
        UIEventListener.Get (gameObject).onClick = OnClick;
        UIEventListener.Get (gameObject).onHover = OnHover;
    }

    // Update is called once per frame
    void Update () { }

    void OnClick (GameObject go) {
        Debug.Log ("OnPointerClick");
    }

    void OnHover (GameObject go, bool _flag) {
        if (_flag) {
            Debug.Log ("OnPointerEnter");
        } else {
            Debug.Log ("OnPointerExit");
        }
    }

}

image.png

不足之处，多谢指正。