Unity UGUI 绑定事件的 4 种方式

1. 可视化创建及事件绑定 #

Step 1 : 通过 Hierarchy 面板创建 UI > Button.

Step 2 : 创建一个脚本 TestClick.cs, 定义了一个 Click 的 public 方法.

Step 3 : 选中 Hierarchy 中的 Button, Add Component 脚本 TestClick.cs

Step 4 : 在 Button(Script) 关联 TestClick 脚本里的 Click 方法.

Step 5 : Done.

TestClick.cs

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

public class TestClick : MonoBehaviour {

    public void Click(){
        Debug.Log ("Button Clicked. TestClick.");
    }
}

2. 通过直接绑定脚本来绑定事件 #

Step 1 : 通过 Hierarchy 面板创建 UI > Button.

Step 2 : 创建一个 ClickHandler.cs 脚本, 定义了一个私有方法 OnClick(), 并在 Start() 方法里为 Button 添加点击事件的监听,作为参数传入 OnClick 方法.

Step 3 : 将 ClickHandler 绑定在 Button 对象上.

Step 4 : Done.

ClickHandler.cs

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

public class ClickHandler : MonoBehaviour {

    void Start () {
        Button btn = this.GetComponent<Button> ();
        btn.onClick.AddListener (OnClick);
    }

    private void OnClick(){
        Debug.Log ("Button Clicked. ClickHandler.");
    }

}

3. 通过 EventTrigger 实现按钮点击事件 #

UGUI 系统中 Button 默认只提供了 OnClick 的调用方法, 有时候我们还需要监听鼠标进入事件 (MouseIn) 和鼠标滑出事件 (MouseOut). 就需要借助 UI 系统中的 EventTrigger 脚本来实现.

Step 1 : 通过 Hierarchy 面板创建 UI > Button.

Step 2 : 创建一个 EventTriggerHandler.cs 脚本, 利用 UnityEngine.EventSystems.EventTrigger 添加监听事件.

Step 3 : 绑定 EventTriggerHandler.cs 脚本到 Button 上.

Step 4 : Done.

EventTriggerHandler.cs

using UnityEngine;
using UnityEngine.EventSystems;


public class EventTriggerHandler: MonoBehaviour {


    EventTrigger trigger;


    void Start()
    {
        trigger= GetComponent<EventTrigger>();


        EventTrigger.Entry ENTER = new EventTrigger.Entry();
        EventTrigger.Entry EXIT = new EventTrigger.Entry();
        EventTrigger.Entry CLICK = new EventTrigger.Entry();
        EventTrigger.Entry DOWN = new EventTrigger.Entry();
        EventTrigger.Entry UP = new EventTrigger.Entry();


        ENTER.eventID = EventTriggerType.PointerEnter;  //鼠标进入事件
        EXIT.eventID = EventTriggerType.PointerExit;  //鼠标滑出事件
        CLICK.eventID = EventTriggerType.PointerClick;  //鼠标点击事件
        DOWN.eventID = EventTriggerType.PointerDown;  //鼠标按下事件
        UP.eventID = EventTriggerType.PointerUp;   //鼠标抬起事件


        ENTER.callback.AddListener(OnPointerEnter);
        EXIT.callback.AddListener(OnPointerExit);
        CLICK.callback.AddListener(OnPointerClick);
        DOWN.callback.AddListener(OnPointerDown);
        UP.callback.AddListener(OnPointerUp);


        trigger.triggers.Add(ENTER);
        trigger.triggers.Add(EXIT);
        trigger.triggers.Add(CLICK);
        trigger.triggers.Add(DOWN);
        trigger.triggers.Add(UP);
    }


    public void OnPointerEnter(BaseEventData pointData)
    {
        print("PointerEnter");
    }


    public void OnPointerExit(BaseEventData pointData)
    {
        print("PointerExit");
    }


    public void OnPointerClick(BaseEventData pointData)
    {
        print("PointerClick");
    }


    public void OnPointerDown(BaseEventData pointData)
    {
        print("PointerDown");
    }


    public void OnPointerUp(BaseEventData pointData)
    {
        print("PointerUp");
    }
}

4. 通过 MonoBehaviour 实现事件类接口来实现事件的监听 #

Step 1 : 通过 Hierarchy 面板创建 UI > Button.

Step 2 : 创建一个 EventHandler.cs 脚本.

Step 3 : 将脚本绑定在 Button 对象上.

Step 4 : Done.

EventHandler.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;

public class EventHandler : MonoBehaviour, IPointerClickHandler, IPointerEnterHandler, IPointerExitHandler, IPointerDownHandler, IDragHandler {

    public void OnPointerClick(PointerEventData eventData){
        if(eventData.pointerId == -1){
            Debug.Log ("Left Mouse Clicked.");
        } else if(eventData.pointerId == -2){
            Debug.Log ("Right Mouse Clicked.");
        }
    }

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

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

    public void OnPointerDown(PointerEventData eventData){
        Debug.Log ("Pointer Down..");
    }

    public void OnDrag(PointerEventData eventData){
        Debug.Log ("Dragged..");
    }

}

UGUI 如何判断 UI 元素被点击时是鼠标的哪个按键, 上面的代码中我们可以根据 eventData.pointerId 来监听是鼠标左键还是右键. 但是每个 UI 元素都创建一个 MonoBehaviour 来监听各个事件显然不好, 下面是通过利用 Delegate 和 Event 来做一个通用类 UIEventListener 来处理事件 (观察者模式).

UIEventListener.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;

public class UIEventListener : MonoBehaviour, IPointerClickHandler, IPointerEnterHandler, IPointerExitHandler {

    // 定义事件代理
    public delegate void UIEventProxy(GameObject gb);

    // 鼠标点击事件
    public event UIEventProxy OnClick;

    // 鼠标进入事件
    public event UIEventProxy OnMouseEnter;

    // 鼠标滑出事件
    public event UIEventProxy OnMouseExit;

    public void OnPointerClick(PointerEventData eventData){
        if (OnClick != null)
            OnClick (this.gameObject);
    }

    public void OnPointerEnter(PointerEventData eventData){
        if (OnMouseEnter != null)
            OnMouseEnter (this.gameObject);
    }

    public void OnPointerExit(PointerEventData eventData){
        if (OnMouseExit != null)
            OnMouseExit (this.gameObject);
    }

}

TestEvent.cs

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

public class TestEvent : MonoBehaviour {

    void Start () {
        Button btn = this.GetComponent<Button> ();
        UIEventListener btnListener = btn.gameObject.AddComponent<UIEventListener> ();

        btnListener.OnClick += delegate(GameObject gb) {
            Debug.Log(gb.name + " OnClick");
        };

        btnListener.OnMouseEnter += delegate(GameObject gb) {
            Debug.Log(gb.name + " OnMouseEnter");
        };

        btnListener.OnMouseExit += delegate(GameObject gb) {
            Debug.Log(gb.name + " OnMOuseExit");
        };
    }

}

TestEvent 脚本绑定在 Button 上即可.

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Project 结构