Unity 新UI事件系统(EventSystem) Demo

新的UI系统消息传递被全新设计，该系统用MonoBehaviour 来实现自定义的接口，以便可以接受来自消息系统的回调。当一个对象被消息的执行指定，那么这个对象的所有实现了自定义接口的脚本将被通知，指定的方法将被执行。

1.定义一个接口ICustomMessageTarget继承IEventSystemHandler， 这样当发送此类型消息时，实现此接口的脚本所在的对象将会被通知。

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

public interface ICustomMessageTarget : IEventSystemHandler
{
    void Message1();
    void Message2();
}

2.测试脚本CustomMessageTarget实现ICustomMessageTarget，加到一个对象上。

using UnityEngine;
using System.Collections;

public class CustomMessageTarget : MonoBehaviour , ICustomMessageTarget
{

    public void Message1()
    {
        Debug.Log("Message1 received.");
    }
    public void Message2()
    {
        Debug.Log("Message2 received.");
    }
}

这样当执行下面代码时事件将被触发

 ExecuteEvents.Execute<ICustomMessageTarget>(go, null, (x, y) => x.Message1());

同时EventSystem还提供了大量的事件， 只需要在脚本中实现这些接口就可以触发相应的方法

• IPointerEnterHandler - OnPointerEnter - Called when a pointer enters the object
• IPointerExitHandler - OnPointerExit - Called when a pointer exits the object
• IPointerDownHandler - OnPointerDown - Called when a pointer is pressed on the object
• IPointerUpHandler - OnPointerUp - Called when a pointer is released (called on the original the pressed object)
• IPointerClickHandler - OnPointerClick - Called when a pointer is pressed and released on the same object
• IInitializePotentialDragHandler - OnInitializePotentialDrag - Called when a drag target is found, can be used to initialise values
• IBeginDragHandler - OnBeginDrag - Called on the drag object when dragging is about to begin
• IDragHandler - OnDrag - Called on the drag object when a drag is happening
• IEndDragHandler - OnEndDrag - Called on the drag object when a drag finishes
• IDropHandler - OnDrop - Called on the object where a drag finishes
• IScrollHandler - OnScroll - Called when a mouse wheel scrolls
• IUpdateSelectedHandler - OnUpdateSelected - Called on the selected object each tick
• ISelectHandler - OnSelect - Called when the object becomes the selected object
• IDeselectHandler - OnDeselect - Called on the selected object becomes deselected
• IMoveHandler - OnMove - Called when a move event occurs (left, right, up, down, ect)
• ISubmitHandler - OnSubmit - Called when the submit button is pressed
• ICancelHandler - OnCancel - Called when the cancel button is pressed

例子：

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

public class TestPointerEnterEvent : MonoBehaviour , IPointerEnterHandler , IPointerClickHandler
{

    public void OnPointerEnter(PointerEventData data)
    {
        Debug.Log("Pointer enter.");
    }

    public void OnPointerClick(PointerEventData data)
    {
        Debug.Log("Pointer click.");
    }
}