UGUI的事件监听机制

来源：互联网发布：编程方法学编辑：程序博客网时间：2024/05/22 01:57

UGUI控件的事件响应有很多种方式，比如使用组件EventTrigger来添加事件监听，或者实现IDragHandler等接口，或者更直接地继承EventTrigger来进行更灵话的调用。

下面分别就上面3种监听方式进行讲解，这些例子都是实现拖动Image的功能。

一、使用组件EventTrigger来添加事件监听

添加一个脚本EventTriggerTest，挂到一个Image上。那么OK，现在可以拖动图片了。

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using UnityEngine;
using UnityEngine.EventSystems;
using Framework;
public class EventTriggerTest : MonoBehaviour
{
public void OnDrag(BaseEventData baseEventData)
{
PointerEventData data = baseEventData as PointerEventData;
var rt = data.pointerPress.GetComponent<RectTransform>();
Vector3 globalMousePos;
if (RectTransformUtility.ScreenPointToWorldPointInRectangle(rt, data.position, data.pressEventCamera, out globalMousePos))
{
rt.position = globalMousePos;
}
}
}

using UnityEngine;using UnityEngine.EventSystems;using Framework;public class EventTriggerTest : MonoBehaviour{    public void OnDrag(BaseEventData baseEventData)    {        PointerEventData data = baseEventData as PointerEventData;        var rt = data.pointerPress.GetComponent<RectTransform>();        Vector3 globalMousePos;        if (RectTransformUtility.ScreenPointToWorldPointInRectangle(rt, data.position, data.pressEventCamera, out globalMousePos))        {            rt.position = globalMousePos;        }    }}

二、实现IDragHandler等接口

UGUI的所有接口如下

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IPointerEnterHandler,
IPointerExitHandler,
IPointerDownHandler,
IPointerUpHandler,
IPointerClickHandler,
IInitializePotentialDragHandler,
IBeginDragHandler,
IDragHandler,
IEndDragHandler,
IDropHandler,
IScrollHandler,
IUpdateSelectedHandler,
ISelectHandler,
IDeselectHandler,
IMoveHandler,
ISubmitHandler,
ICancelHandler

        IPointerEnterHandler,        IPointerExitHandler,        IPointerDownHandler,        IPointerUpHandler,        IPointerClickHandler,        IInitializePotentialDragHandler,        IBeginDragHandler,        IDragHandler,        IEndDragHandler,        IDropHandler,        IScrollHandler,        IUpdateSelectedHandler,        ISelectHandler,        IDeselectHandler,        IMoveHandler,        ISubmitHandler,        ICancelHandler

这里就实现IDragHandler接口，来实现Image的拖动。添加脚本EventInterfaceTest，挂到Image上。

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using UnityEngine;
using UnityEngine.EventSystems;
class EventInterfaceTest : MonoBehaviour, IDragHandler
{
public void OnDrag(PointerEventData data)
{
var rt = gameObject.GetComponent<RectTransform>();
Vector3 globalMousePos;
if (RectTransformUtility.ScreenPointToWorldPointInRectangle(rt, data.position, data.pressEventCamera, out globalMousePos))
{
rt.position = globalMousePos;
}
}
}

using UnityEngine;using UnityEngine.EventSystems;class EventInterfaceTest : MonoBehaviour, IDragHandler{    public void OnDrag(PointerEventData data)    {        var rt = gameObject.GetComponent<RectTransform>();        Vector3 globalMousePos;        if (RectTransformUtility.ScreenPointToWorldPointInRectangle(rt, data.position, data.pressEventCamera, out globalMousePos))        {            rt.position = globalMousePos;        }    }}

三、继承EventTrigger来进行更灵话的调用

如果GameObject是动态创建的，那么就不方便用Unity编辑器加EventTrigger监听，所以要是能用代码方便地进行监听，又不需要重写那么多接口，那是最好不过了。

首先添加脚本UGUIEventTrigger

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using System.Collections.Generic;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.Events;
namespace Framework
{
public class UGUIEventTrigger : EventTrigger
{
public static UGUIEventTrigger Get(GameObject go)
{
UGUIEventTrigger trigger = go.GetComponent<UGUIEventTrigger>();
if (null == trigger)
{
trigger = go.AddComponent<UGUIEventTrigger>();
}
return trigger;
}
public void AddEventListener(EventTriggerType eventTriggerType, UnityAction<BaseEventData> action)
{
EventTrigger.Entry entry = new EventTrigger.Entry();
entry.eventID = eventTriggerType;
entry.callback.AddListener(action);
if (null == delegates)
{
delegates = new List<Entry>();
}
delegates.Add(entry);
}
}
}

using System.Collections.Generic;using UnityEngine;using UnityEngine.EventSystems;using UnityEngine.Events;namespace Framework{    public class UGUIEventTrigger : EventTrigger    {        public static UGUIEventTrigger Get(GameObject go)        {            UGUIEventTrigger trigger = go.GetComponent<UGUIEventTrigger>();            if (null == trigger)            {                trigger = go.AddComponent<UGUIEventTrigger>();            }            return trigger;        }        public void AddEventListener(EventTriggerType eventTriggerType, UnityAction<BaseEventData> action)        {            EventTrigger.Entry entry = new EventTrigger.Entry();            entry.eventID = eventTriggerType;            entry.callback.AddListener(action);            if (null == delegates)            {                delegates = new List<Entry>();            }            delegates.Add(entry);        }    }}

然后编写测试脚本，挂到Image上。

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using UnityEngine;
using UnityEngine.EventSystems;
public class UGUIEventTriggerTest : MonoBehaviour
{
void Start()
{
UGUIEventTrigger.Get(gameObject).AddEventListener(EventTriggerType.Drag, OnDrag);
}
private void OnDrag(BaseEventData baseData)
{
PointerEventData data = baseData as PointerEventData;
var rt = data.pointerPress.GetComponent<RectTransform>();
Vector3 globalMousePos;
if (RectTransformUtility.ScreenPointToWorldPointInRectangle(rt, data.position, data.pressEventCamera, out globalMousePos))
{
rt.position = globalMousePos;
}
}
}

using UnityEngine;using UnityEngine.EventSystems;public class UGUIEventTriggerTest : MonoBehaviour{    void Start()    {        UGUIEventTrigger.Get(gameObject).AddEventListener(EventTriggerType.Drag, OnDrag);    }    private void OnDrag(BaseEventData baseData)    {        PointerEventData data = baseData as PointerEventData;        var rt = data.pointerPress.GetComponent<RectTransform>();        Vector3 globalMousePos;        if (RectTransformUtility.ScreenPointToWorldPointInRectangle(rt, data.position, data.pressEventCamera, out globalMousePos))        {            rt.position = globalMousePos;        }    }}

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