UGUI EventSystems UI拖拽

UGUI中 關於事件的觸發，它給咱們提供了大概十七個接口可用來使用，各個接口的做用以及實現方法能夠查閱Unity官方API：

file:///D:/Unity5.0.1/Unity/Editor/Data/Documentation/en/ScriptReference/index.html。想看具體的例子能夠借鑑Unity提供的UGUI官方實例：http://pan.baidu.com/s/1mgmpgHM

裏面也有作好的拖拽實例。這邊我貼出簡單的拖拽代碼，可以讓你更容易看懂實例：

完成拖拽須要兩個腳本   一個是drag對象 ， 一個是drop對象：

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

public class dragme : MonoBehaviour,IDragHandler,IBeginDragHandler,IEndDragHandler
{
    //生成的icon
    private GameObject draged_icon;

    public void OnBeginDrag(PointerEventData eventData)
    {
       //設置icon屬性，添加組件
        draged_icon = new GameObject("icon");
        draged_icon.transform.SetParent(GameObject.Find("Canvas").transform, false);

        draged_icon.AddComponent<RectTransform>();
        draged_icon.AddComponent<Image>();
        draged_icon.GetComponent<Image>().sprite = GetComponent<Image>().sprite;

        //讓圖標不執行事件檢測，防止icon妨礙後面的event system
        CanvasGroup group = draged_icon.AddComponent<CanvasGroup>();
        group.blocksRaycasts = false;
    }

    public void OnDrag(PointerEventData eventData)
    {
        //在RectTransform下 實現鼠標 物體的跟隨效果
        Vector3 worldpos;
        if (RectTransformUtility.ScreenPointToWorldPointInRectangle(draged_icon.GetComponent<RectTransform>(), eventData.position, Camera.main, out worldpos))
        {
            draged_icon.transform.position = worldpos;
        }

    }

    public void OnEndDrag(PointerEventData eventData)
    {
        //銷燬圖標
        if (draged_icon != null)
        {
            Destroy(draged_icon.gameObject);
        }
    }
}

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

public class Dropme : MonoBehaviour,IPointerEnterHandler,IPointerExitHandler,IDropHandler
{
    //鼠標進入
    public void OnPointerEnter(PointerEventData eventData)
    {
       //有拖拽物，drop區域變色，不然return
        GameObject dragobj = eventData.pointerDrag;

        if (dragobj == null) return;

        GetComponent<Image>().color = Color.grey;
    }

    //鼠標離開 重置顏色white
    public void OnPointerExit(PointerEventData eventData)
    {
        GetComponent<Image>().color = Color.white;
    }

    //drop 賦予拖拽物體sprite
    public void OnDrop(PointerEventData eventData)
    {
        GameObject dragobj = eventData.pointerDrag;

       // if (dragobj == null) return;

        GetComponent<Image>().sprite = dragobj.GetComponent<Image>().sprite;

        GetComponent<Image>().color = Color.white;
    }
}