本例項通過UGUI實現揹包的簡單功能，物品的拖拽，交換，拖放位置處理，還有針對揹包多頁面的滑動翻頁的處理。

具體的程式碼如下。

首先是UIItem類，這個揹包內各種物體的類：

using UnityEngine;
using System.Collections;
using UnityEngine.UI;
public class UIItem : MonoBehaviour {
    public Text name;
    public Image image;

    public void Show(string name)
    {
        this.name.text = name;
    }

}
 

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using UnityEngine.EventSystems;
using UnityEngine.UI;
public class DragEvent : MonoBehaviour,IBeginDragHandler ,IDragHandler ,IEndDragHandler ,IPointerDownHandler ,IPointerUpHandler {

    public RectTransform rectTransform;
    public RectTransform rectTransformSlot;
    public Transform draggedItemBox;
    private Vector2 pointerOffset;
    public CanvasGroup canvasGroup;
    public Transform grid;

    /// <summary>
    /// 開始拖拽！
    /// </summary>
    /// <param name="eventData"></param>
    public void OnBeginDrag(PointerEventData eventData)
    {
        SetDraggedPosition(eventData);
    }
    /// <summary>
    /// 設定拖拽開始和結束的位置
    /// </summary>
    /// <param name="eventData"></param>
    private void SetDraggedPosition(PointerEventData eventData)
    {
        if (rectTransform == null)
            return;

        if(eventData .button ==PointerEventData .InputButton .Left )
        {
            //把世界座標轉換為區域性座標
            rectTransform.SetAsLastSibling();

            transform.SetParent(draggedItemBox);
            Vector2 localPointerPosition;
            //畫布是否接受射線
            canvasGroup.blocksRaycasts = false;
            if(RectTransformUtility .ScreenPointToLocalPointInRectangle (rectTransformSlot ,Input .mousePosition ,
                eventData .pressEventCamera ,out localPointerPosition ))
            {
                rectTransform.localPosition = localPointerPosition - pointerOffset;
            }
        } 
    }

    public void OnDrag(PointerEventData eventData)
    {
        SetDraggedPosition(eventData);
    }

    public void OnEndDrag(PointerEventData eventData)
    {
        SetDraggedPosition(eventData);
        canvasGroup.blocksRaycasts = true;

        if(eventData .pointerCurrentRaycast .gameObject .name =="skill")
        {
            transform.SetParent(eventData.pointerCurrentRaycast.gameObject.transform);
            transform.position = eventData.pointerCurrentRaycast.gameObject.transform.position;
        }
        else if(eventData .pointerCurrentRaycast .gameObject .name =="Text99")
        {
            this.transform.SetParent(eventData.pointerCurrentRaycast.gameObject.transform.parent.parent);
            transform.position = eventData.pointerCurrentRaycast.gameObject.transform.parent.parent.position;
            eventData.pointerCurrentRaycast.gameObject.transform.parent.SetParent(grid);
        }
        else
        {
            transform.SetParent(grid);
        }
    }

    public void OnPointerDown(PointerEventData eventData)
    {
        transform.localPosition = Vector3.one * 0.5f;
    }

    public void OnPointerUp(PointerEventData eventData)
    {
        transform.localPosition = Vector3.one;
    }
}
 

最後的對畫布和Scroll的類處理：

using UnityEngine;
using System.Collections;
using UnityEngine.UI;
using UnityEngine.EventSystems;
using System.Collections.Generic;
using System;
public class ScrollRectHelper : MonoBehaviour ,IBeginDragHandler ,IEndDragHandler {
    /// <summary>
    /// 滑動速度
    /// </summary>
    private float smooting = 2;
    /// <summary>
    /// 每頁顯示的數目
    /// </summary>
    private int pageCount = 16;

    private ScrollRect sRect;
    /// <summary>
    /// 總頁數
    /// </summary>
    private float pageIndex;
    /// <summary>
    /// 是否拖拽結束
    /// </summary>
    private bool isDrag = false;
    /// <summary>
    /// 總頁數索引比例
    /// </summary>
    private List<float> listPageValue = new List<float> { 0 };
    /// <summary>
    /// 滑動目標位置
    /// </summary>
    float targetPos = 0;
    /// <summary>
    /// 當前索引位置
    /// </summary>
    float nowIndex = 0;

    public GameObject UIItem;

    private int count;
    void Awake()
    {
        sRect = GetComponent<ScrollRect>();
        ListPageValueInit();
    }


    /// <summary>
    /// 初始化UIItem
    /// </summary>
    void Start()
    {
        for (int i = 0; i < count ; i++)
        {
            GameObject go = Instantiate(UIItem);
            go.name += +i;
            go.SetActive(true);
            go.transform.localPosition = UIItem.transform.localPosition;
            go.transform.parent = UIItem.transform.parent;
            go.GetComponent<UIItem>().Show("物品" + i);
        }
    }
    /// <summary>
    /// 每頁比例
    /// </summary>
    private void ListPageValueInit()
    {
        pageIndex = (count / pageCount) - 1;
        if(count !=0)
        {
            for (int i = 1; i < pageIndex ; i++)
            {
                listPageValue.Add((i / pageIndex));
            }
        }
    }

    void Update()
    {
        if(!isDrag )
        {
            sRect.horizontalNormalizedPosition = Mathf.Lerp(sRect.horizontalNormalizedPosition, targetPos, Time.deltaTime);
        }
    }


    /// <summary>
    /// 開始拖拽
    /// </summary>
    /// <param name="eventData"></param>
    public void OnBeginDrag(PointerEventData eventData)
    {
        isDrag = true;
    }
    /// <summary>
    /// 拖拽結束
    /// </summary>
    /// <param name="eventData"></param>
    public void OnEndDrag(PointerEventData eventData)
    {
        isDrag = false;
        //獲取拖動的值
        float  tempPos = sRect.horizontalNormalizedPosition;
        var index = 0;
        //拖動的絕對值
        float offset = Mathf.Abs(listPageValue[index] - tempPos);

        for (int i = 0; i < listPageValue .Count ; i++)
        {
            float temp = Mathf.Abs(tempPos - listPageValue[i]);
            if(temp <offset )
            {
                index = i;
                offset = temp;
            }
        }

        targetPos = listPageValue[index];
        nowIndex = index;
    }

    #region 如果需要分頁，此處為左右分頁程式碼，現有功能不需要，所以註釋掉了
    //public void BtnLeftGo()
    //{
    //    nowindex = Mathf.Clamp(nowindex - 1, 0, pageIndex);
    //    targetPos = listPageValue[Convert.ToInt32(nowindex)];
    //}

    //public void BtnRightGo()
    //{
    //    nowindex = Mathf.Clamp(nowindex + 1, 0, pageIndex);
    //    targetPos = listPageValue[Convert.ToInt32(nowindex)];

    //}
    #endregion
}