UGUI 視覺化建立以及關聯事件很方便, 動態建立可以利用建立好的 Prefab 進行例項化, 只是在關聯事件上有些複雜, 本文總結了幾種給按鈕繫結事件的關聯方式.

1. 視覺化建立及事件繫結 #
Step 1 : 通過 Hierarchy 面板建立 UI > Button.

Step 2 : 建立一個指令碼 TestClick.cs, 定義了一個 Click 的 public 方法.

Step 3 : 選中 Hierarchy 中的 Button, Add Component 指令碼 TestClick.cs

Step 4 : 在 Button(Script) 關聯 TestClick 腳本里的 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. 通過直接繫結指令碼來繫結事件 #
Step 1 : 通過 Hierarchy 面板建立 UI > Button.

Step 2 : 建立一個 ClickHandler.cs 指令碼, 定義了一個私有方法 OnClick(), 並在 Start() 方法裡為 Button 新增點選事件的監聽,作為引數傳入 OnClick 方法.

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. 通過 EventTrigger 實現按鈕點選事件 #
UGUI 系統中 Button 預設只提供了 OnClick 的呼叫方法, 有時候我們還需要監聽滑鼠進入事件 (MouseIn) 和滑鼠滑出事件 (MouseOut). 就需要藉助 UI 系統中的 EventTrigger 指令碼來實現.

Step 1 : 通過 Hierarchy 面板建立 UI > Button.

Step 2 : 建立一個 EventTriggerHandler.cs 指令碼, 利用 UnityEngine.EventSystems.EventTrigger 新增監聽事件.

Step 3 : 繫結 EventTriggerHandler.cs 指令碼到 Button 上.

Step 4 : Done.

EventTriggerHandler.cs

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

// 需要 EventTrigger 指令碼的支援
[RequireComponent(typeof(UnityEngine.EventSystems.EventTrigger))]
public class EventTriggerHandler : MonoBehaviour {

// Use this for initialization
void Start () {
    Button btn = this.GetComponent<Button> ();
    EventTrigger trigger = btn.gameObject.GetComponent<EventTrigger> ();
    EventTrigger.Entry entry = new EventTrigger.Entry ();
    // 滑鼠點選事件
    entry.eventID = EventTriggerType.PointerClick;
    // 滑鼠進入事件 entry.eventID = EventTriggerType.PointerEnter;
    // 滑鼠滑出事件 entry.eventID = EventTriggerType.PointerExit;
    entry.callback = new EventTrigger.TriggerEvent ();
    entry.callback.AddListener (OnClick);
    // entry.callback.AddListener (OnMouseEnter);
    trigger.triggers.Add (entry);
}

private void OnClick(BaseEventData pointData){
    Debug.Log ("Button Clicked. EventTrigger..");
}

private void OnMouseEnter(BaseEventData pointData){
    Debug.Log ("Button Enter. EventTrigger..");
}

}
4. 通過 MonoBehaviour 實現事件類介面來實現事件的監聽 #
Step 1 : 通過 Hierarchy 面板建立 UI > Button.

Step 2 : 建立一個 EventHandler.cs 指令碼.

Step 3 : 將指令碼繫結在 Button 物件上.

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 如何判斷 UI 元素被點選時是滑鼠的哪個按鍵, 上面的程式碼中我們可以根據 eventData.pointerId 來監聽是滑鼠左鍵還是右鍵. 但是每個 UI 元素都建立一個 MonoBehaviour 來監聽各個事件顯然不好, 下面是通過利用 Delegate 和 Event 來做一個通用類 UIEventListener 來處理事件 (觀察者模式).

UIEventListener.cs

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

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

// 定義事件代理
public delegate void UIEventProxy(GameObject gb);

// 滑鼠點選事件
public event UIEventProxy OnClick;

// 滑鼠進入事件
public event UIEventProxy OnMouseEnter;

// 滑鼠滑出事件
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 指令碼繫結在 Button 上即可.