public class UIScrollViewTest : MonoBehaviour {
 
 public RectTransform content;
 public GameObject cell;
 // cell的初始化個數
 public int cellAmount = 0;
 // 鼠標上滑時，存儲Cell的Queue。正序存儲
 public Queue F_cellQuee = new Queue();
 // 鼠標下滑時，存儲Cell的Queue。到序存儲
 public Queue B_cellQuee = new Queue();
 // cell的Size
 public Vector2 cellSize = new Vector2(100,100);
 // cell的間隔
 public Vector2 cellOffset = new Vector2(0,0);
 // 列數
 public int columnCount = 0;
 private int rowCount;
 // 上一次content的位置
 public float lastPos;
 // 滾動的次數
 public int loopCount = 0;
 // cell顯示的數據段的開頭和結尾序號
 public int HeadNum = 0;
 public int TailNum;
 
 public Sprite[] sp;
 public List<Sprite> data;
 
 
 void Start()
 {
  for (int i = 0; i < sp.Length; i++)
  {
   data.Add(sp[i]);
  }
 
  InitialScrollView(data);
  TailNum = cellAmount-1;
  lastPos = content.localPosition.y;
  //Debug.LogError("行數是：：：" + rowCount);
 
  //Debug.LogError("+++++++++++++++++ " + (5>>3));
 }
 
 
 void Update()
 {
  // 觸發滾動。
  if (content.localPosition.y - lastPos > cellSize.y && data.Count - cellAmount - loopCount*columnCount >0)
  {
   //Debug.LogError("11111111111 " + (data.Count - cellAmount - loopCount * columnCount));
   LoopScrolView(data);
   lastPos = content.localPosition.y;
  }
 }
 
 
 
 
 // 初始化cell
 void InitialScrollView(List<Sprite> data)
 {
  for (int i = 0; i < cellAmount; i++)
  {
   GameObject obj = Instantiate(cell.gameObject);
   obj.transform.SetParent(content);
   obj.name = "cell0" + i.ToString();
   obj.transform.GetChild(0).GetComponent<Text>().text = "cell0"+i.ToString();
   // 顯示默認的數據
   obj.GetComponent<Image>().sprite = data[i];
  }
  // 初始化Queue
  for (int i = content.childCount-1; i >= 0; i--)
  {
   B_cellQuee.Enqueue(content.GetChild(i).gameObject);
  }
  for (int i = 0; i < content.childCount; i++)
  {
   F_cellQuee.Enqueue(content.GetChild(i).gameObject);
  }
 
  // 計算行數
  if (cellAmount % columnCount >0)
  {
   rowCount = cellAmount / columnCount + 1;
  } else {
   rowCount = cellAmount / columnCount;
  }
 
  // 排列cell的位置
  int index = 0;
  for (int r = 1; r <= rowCount; r++)
  {
   for (int c = 1; c <= columnCount; c++)
   {
    if (index < cellAmount)
    {
     Vector2 pos = new Vector2(cellSize.x / 2 + (cellSize.x + cellOffset.x) * (c-1), -cellSize.y / 2 - (cellOffset.y + cellSize.y) * (r-1));
     content.GetChild(index).GetComponent<RectTransform>().SetInsetAndSizeFromParentEdge(RectTransform.Edge.Top, 0, 100);
     content.GetChild(index).GetComponent<RectTransform>().SetInsetAndSizeFromParentEdge(RectTransform.Edge.Left, 0, 100);
     content.GetChild(index).GetComponent<RectTransform>().anchoredPosition = pos;
     index++;
    }
   }
  }
 
  Vector2 v = content.sizeDelta;
  // 初始化content的size
  content.sizeDelta = new Vector2(v.x, rowCount * cellSize.y + cellOffset.y*(rowCount-1));
 }
 
 
 /// 保持content的大小，這里是保持大小為在cell的行數基礎上，向下多出bottomCount行的距離
 void SetContentSize(int upperCount, int bottomCount)
 {
  if (content.sizeDelta != new Vector2(content.sizeDelta.x, content.sizeDelta.y + bottomCount * (cellSize.y + cellOffset.y)))
  {
   content.sizeDelta = new Vector2(content.sizeDelta.x, content.sizeDelta.y + bottomCount*(cellSize.y + cellOffset.y));
  }
 }
 
 // 計算頂部的Cell輪換到底部時的位置。以當前最后一行的最后一個Cell的位置為基準計算。
 void SetBottomCellPosition(int index, RectTransform rect, Vector2 pos)
 {
  Vector2 v = Vector2.zero;
  if (cellAmount % columnCount == 0) // 整除。每一行都滿的情況。
  {
   float x = pos.x - cellSize.x * (columnCount - index-1) - cellOffset.x * (columnCount-index-1);
   float y = pos.y - cellSize.y - cellOffset.y;
   v = new Vector2(x,y);
  }
  // 出現不滿行的情況。例如數據有103個，可以用23個cell來輪換。這樣就會出現不滿行的情況。
  // 這種情況下是頂部的一行cell順次接到底部不滿的行。例如23號cell后面接1號和2號cell，3號和4號cell填充到第“7”行
  else if (cellAmount % columnCount + index+1<=columnCount) 
  {
   float x = pos.x + cellSize.x * (index+1) + cellOffset.x * (index+1);
   float y = pos.y;
   v = new Vector2(x, y);
  }
  else
  {
   float x = pos.x - cellSize.x * (columnCount - index-1) - cellOffset.x * (columnCount - index-1);
   float y = pos.y - cellSize.y - cellOffset.y;
   v = new Vector2(x, y);
  }
  //Debug.LogError("++++++++++++++ " + pos+ "     "+ v);
  rect.anchoredPosition = v;
  rect.SetAsLastSibling();
 }
 
 // 計算底部的cell輪換到頂部是的位置，基準位置是當前行的第一個cell。
 void SetUpperCellPosition(int index, RectTransform rect, Vector2 pos)
 {
  Vector2 v = Vector2.zero;
  if (cellAmount % columnCount == 0) // 整除
  {
   float x = pos.x + cellSize.x * index + cellOffset.x * index;
   float y = pos.y + cellSize.y + cellOffset.y;
   v = new Vector2(x, y);
  }
  //else if (cellAmount % columnCount + index + 1 <= columnCount)
  //{
  // float x = pos.x + cellSize.x * (index + 1) + cellOffset.x * (index + 1);
  // float y = pos.y;
  // v = new Vector2(x, y);
  //}
  //else
  //{
  // float x = pos.x - cellSize.x * (columnCount - index - 1) - cellOffset.x * (columnCount - index - 1);
  // float y = pos.y - cellSize.y - cellOffset.y;
  // v = new Vector2(x, y);
  //}
  //Debug.LogError("++++++++++++++ " + pos+ "     "+ v);
  rect.anchoredPosition = v;
  rect.SetAsFirstSibling();
 }
 
 
 // 鼠標上滑時，顯示當前cell的數據。同時記錄數據段的序號遞增。
 void ShowRestCellData(Image cell, int index)
 {
  if (TailNum< data.Count-1)
  {
   Debug.LogError("當前的序號是：：：：" + TailNum);
   TailNum++;
   HeadNum++;
   cell.sprite = data[TailNum];
  }
 }
 
 void ShowPreviousCellData(Image cell, int index)
 {
  if (HeadNum > 0)
  {
   Debug.LogError("當前的序號是：：：：" + HeadNum);
   TailNum--;
   HeadNum--;
   cell.sprite = data[HeadNum];
  }
 }
 
 
 // 輪換的函數。每次亂換一行的cell。
 void LoopScrolView(List<Sprite> data)
 {
  SetContentSize(0, 1);
  loopCount++;
  RectTransform rect2 = content.GetChild(content.childCount - 1).GetComponent<RectTransform>();
  for (int i = 0; i < columnCount; i++)
  {
   GameObject obj = F_cellQuee.Dequeue() as GameObject;
   RectTransform rect = obj.GetComponent<RectTransform>();
   ShowRestCellData(obj.GetComponent<Image>(), i);
   SetBottomCellPosition(i, rect, rect2.anchoredPosition);
   F_cellQuee.Enqueue(obj);
  }
 }
 
}