【Unity3D】UGUI回调函数

1 简述

        UGUI 回调函数主要指鼠标进入、离开、点下、点击中、抬起、开始拖拽、拖拽中、拖拽结束 UI 控件触发的回调。使用 UGUI 回调函数时，需要引入 UnityEngine.EventSystems 命名空间。

        1） 回调函数

回调函数	接口	说明
void OnPointerEnter(PointerEventData eventData)	IPointerEnterHandler	鼠标进入
void OnPointerExit(PointerEventData eventData)	IPointerExitHandler	鼠标离开
void OnPointerDown(PointerEventData eventData)	IPointerDownHandler	鼠标点下
void OnPointerClick(PointerEventData eventData)	IPointerClickHandler	鼠标点击中
void OnPointerUp(PointerEventData eventData)	IPointerUpHandler	鼠标抬起
void OnBeginDrag(PointerEventData eventData)	IBeginDragHandler	鼠标开始拖拽
void OnDrag(PointerEventData eventData)	IDragHandler	鼠标拖拽中
void OnEndDrag(PointerEventData eventData)	IEndDragHandler	鼠标结束拖拽

        2）前提条件

• 当前 UI 对象必须至少有 1 个基础组件（Text、Image、RawImage）
• 基础 UI 组件中必须勾选 Raycast Target
• 代码引入 UnityEngine.EventSystems 命名空间

        3）使用方法

using UnityEngine;
using UnityEngine.EventSystems;

public class EventController : MonoBehaviour,
		IPointerEnterHandler,
		IPointerExitHandler,
		IPointerDownHandler,
		IPointerClickHandler,
		IPointerUpHandler,
		IBeginDragHandler,
		IDragHandler,
		IEndDragHandler {

	public void OnPointerEnter(PointerEventData eventData) {
		Debug.Log("OnPointerEnter");
	}

	public void OnPointerExit(PointerEventData eventData) {
		Debug.Log("OnPointerExit");
	}

	public void OnPointerDown(PointerEventData eventData) {
		Debug.Log("OnPointerDown");
	}

	public void OnPointerClick(PointerEventData eventData) {
		Debug.Log("OnPointerClick");
	}

	public void OnPointerUp(PointerEventData eventData) {
		Debug.Log("OnPointerUp");
	}

	public void OnBeginDrag(PointerEventData eventData) {
		Debug.Log("OnBeginDrag");
	}

	public void OnDrag(PointerEventData eventData) {
		Debug.Log("OnDrag");
	}

	public void OnEndDrag(PointerEventData eventData) {
		Debug.Log("OnEndDrag");
	}
}

2 应用

        1）UGUI 控件

        分别创建 Panel 和 2 个 Image 控件，并将 Image 控件重命名为 Monster 和 Spear，如下：

         给 Monster 和 Spear 添加 Sprite 图片如下：

        2）脚本组件

        SpearController.cs

using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;

public class SpearController : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler {
	private bool isDragging = false;

	public void OnBeginDrag(PointerEventData eventData) {
		GetComponent().raycastTarget = false;
		isDragging = true;
	}

	public void OnDrag(PointerEventData eventData) {
		transform.position = Input.mousePosition;
	}

	public void OnEndDrag(PointerEventData eventData) {
		GetComponent().raycastTarget = true;
		isDragging = false;
	}

	public bool IsDragging() {
		return isDragging;
	}
}

         说明：SpearController 脚本组件附着在 Spear 对象上。

        MonsterController.cs

using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;

public class MonsterController : MonoBehaviour, IPointerEnterHandler, IPointerExitHandler {
	private Image image;
	private SpearController spear;

	private void Start() {
		image = GetComponent();
		spear = GameObject.Find("Spear").GetComponent();
	}

	public void OnPointerEnter(PointerEventData eventData) {
		if (spear.IsDragging()) {
			image.color = Color.red;
		}
	}

	public void OnPointerExit(PointerEventData eventData) {
		if (spear.IsDragging()) {
			image.color = Color.white;
		}
	}
}

        说明：MonsterController 脚本组件附着在 Monster 对象上。

        3）运行效果