添加鼠标侦听器

有时，你希望在组件本身提供的特定事件（特别是鼠标事件）上添加侦听器。为此，你必须使用 EventTrigger 组件自行添加它们：

using UnityEngine;
using UnityEngine.EventSystems;

[RequireComponent(typeof( EventTrigger ))]
public class CustomListenersExample : MonoBehaviour
{
    void Start( )
    {
        EventTrigger eventTrigger = GetComponent<EventTrigger>( );
        EventTrigger.Entry entry = new EventTrigger.Entry( );
        entry.eventID = EventTriggerType.PointerDown;
        entry.callback.AddListener( ( data ) => { OnPointerDownDelegate( (PointerEventData)data ); } );
        eventTrigger.triggers.Add( entry );
    }

    public void OnPointerDownDelegate( PointerEventData data )
    {
        Debug.Log( "OnPointerDownDelegate called." );
    }
}

各种 eventID 都是可能的：

• PointerEnter
• PointerExit
• PointerDown
• PointerUp
• PointerClick
• 拖动
• 下降
• 滚动
• UpdateSelected
• 选择
• 取消
• 移动
• InitializePotentialDrag
• BeginDrag
• EndDrag
• 提交
• 取消