c# - Unity3d - 在另一个脚本中定义事件

Question

假设我想向下拉元素的 OnSelect() 事件添加功能。

通常我会向特定的下拉游戏对象添加一个新脚本:

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

public class LanguageDropdown : MonoBehaviour, ISelectHandler// required interface when using the OnSelect method.
{
    //Do this when the selectable UI object is selected.
    public void OnSelect(BaseEventData eventData)
    {
        Debug.Log(this.gameObject.name + " was selected");
    }
}

提示:如果下拉菜单被选中，脚本将简单地输出一条消息。

---

问题:是否可以在另一个脚本中定义功能？例如。我有一个脚本附加到主父“Menue”，我在其中引用这个特定的下拉游戏对象。

如何在另一个脚本中定义 OnSelect？

PS:这是问这个问题的正确地点，还是我应该在 gamedevelopement 上问这个问题？

Answer 1

使用事件和委托(delegate)。您可以找到该内容的简化教程 here如果这对您来说是新的。

应该是这样的:

public delegate void SelectAction(GameObject target);
public static event SelectAction OnSelectedEvent;

将其添加到您的 LanguageDropdown 脚本中，您应该得到:

public class LanguageDropdown : MonoBehaviour, ISelectHandler// required interface when using the OnSelect method.
{
    public delegate void SelectAction(GameObject target);
    public static event SelectAction OnSelectedEvent;

    //Do this when the selectable UI object is selected.
    public void OnSelect(BaseEventData eventData)
    {
        Debug.Log(this.gameObject.name + " was selected");

        //Invoke Event
        if (OnSelectedEvent != null)
        {
            OnSelectedEvent(this.gameObject);
        }
    }
}

现在，您可以从另一个脚本分别在 OnEnable 和 OnDisable 函数中订阅和取消订阅事件:

void OnEnable()
{
    //subscribe to event
    LanguageDropdown.OnSelectedEvent += SelectAction;
}

void OnDisable()
{
    //Un-subscribe to event
    LanguageDropdown.OnSelectedEvent -= SelectAction;
}

//This will be called when invoked
void SelectAction(GameObject target)
{
    Debug.Log(target.name + " was selected");
}

Basically I wanted to know if I am forced to attach the script LanguageDropdown to the gameobject, or If this is not required and I can setup everything from another script which is not attached to that specific dropdown.

不，您可以使用 EventTrigger 类来注册如下事件，而不必将其附加到每个对象:

EventTrigger.Entry entry = new EventTrigger.Entry();
entry.eventID = EventTriggerType.Select;
entry.callback.AddListener((eventData) => { SelectAction(); });

请不要使用它。它很慢，我也从多人那里验证了这一点。