Unity UGUI —— 无限循环List(转载)

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using UnityEngine.UI;
/// <summary>
/// 无限循环List
/// 作者：EdisonLee
///
public class UILoop1 : UIBase
{

enum Direction
{
Horizontal,
Vertical
}

[SerializeField]
private RectTransform m_Cell;

[SerializeField]
private Vector2 m_Page;

[SerializeField]
Direction direction = Direction.Horizontal;

[SerializeField,Range(4,10)]
private int m_BufferNo;

private List<RectTransform> m_InstantiateItems = new List<RectTransform>();

private IList m_Datas;

public Vector2 CellRect { get { return m_Cell != null ? m_Cell.sizeDelta : new Vector2(100, 100); } }

public float CellScale { get { return direction == Direction.Horizontal ? CellRect.x : CellRect.y; } }

private float m_PrevPos = 0;
public float DirectionPos { get { return direction == Direction.Horizontal ? m_Rect.anchoredPosition.x : m_Rect.anchoredPosition.y; } }

private int m_CurrentIndex;//页面的第一行（列）在整个conten中的位置

private Vector2 m_InstantiateSize = Vector2.zero;
public Vector2 InstantiateSize
{
get
{
if (m_InstantiateSize == Vector2.zero)
{
float rows, cols;
if (direction == Direction.Horizontal)
{
rows = m_Page.x;
cols = m_Page.y + (float)m_BufferNo;
}
else
{
rows = m_Page.x + (float)m_BufferNo;
cols = m_Page.y;
}
m_InstantiateSize = new Vector2(rows, cols);
}
return m_InstantiateSize;
}
}

public int PageCount { get { return (int)m_Page.x * (int)m_Page.y; } }

public int PageScale { get { return direction == Direction.Horizontal ? (int)m_Page.x : (int)m_Page.y; } }

private ScrollRect m_ScrollRect;

private RectTransform m_Rect;
public int InstantiateCount { get { return (int)InstantiateSize.x * (int)InstantiateSize.y; } }
protected override void Awake()
{
m_ScrollRect = GetComponentInParent<ScrollRect>();
m_ScrollRect.horizontal = direction == Direction.Horizontal;
m_ScrollRect.vertical = direction == Direction.Vertical;

m_Rect = GetComponent<RectTransform>();

m_Cell.gameObject.SetActive(false);
}

public override void Data(object data)
{
m_Datas = data as IList;

if (m_Datas.Count > PageCount)
{
setBound(getRectByNum(m_Datas.Count));
}
else
{
setBound(m_Page);
}

if (m_Datas.Count > InstantiateCount)
{
while (m_InstantiateItems.Count < InstantiateCount)
{
createItem(m_InstantiateItems.Count);
}
}
else
{
while (m_InstantiateItems.Count > m_Datas.Count)
{
removeItem(m_InstantiateItems.Count - 1);
}

while (m_InstantiateItems.Count < m_Datas.Count)
{
createItem(m_InstantiateItems.Count);
}
}
}

private void createItem(int index)
{
RectTransform item = GameObject.Instantiate(m_Cell);
item.SetParent(transform, false);
item.anchorMax = Vector2.up;
item.anchorMin = Vector2.up;
item.pivot = Vector2.up;
item.name = "item" + index;

item.anchoredPosition = direction == Direction.Horizontal ?
new Vector2(Mathf.Floor(index / InstantiateSize.x) * CellRect.x, -(index % InstantiateSize.x) * CellRect.y) :
new Vector2((index % InstantiateSize.y) * CellRect.x, -Mathf.Floor(index / InstantiateSize.y) * CellRect.y);
m_InstantiateItems.Add(item);
item.gameObject.SetActive(true);

updateItem(index, item.gameObject);
}

private void removeItem(int index)
{
RectTransform item = m_InstantiateItems[index];
m_InstantiateItems.Remove(item);
RectTransform.Destroy(item.gameObject);
}
/// <summary>
/// 由格子数量获取多少行多少列
/// </summary>
/// <param name="num"></param>格子个数
/// <returns></returns>
private Vector2 getRectByNum(int num)
{
return direction == Direction.Horizontal ?
new Vector2(m_Page.x, Mathf.CeilToInt(num / m_Page.x)) :
new Vector2(Mathf.CeilToInt(num / m_Page.y), m_Page.y);

}
/// <summary>
/// 设置content的大小
/// </summary>
/// <param name="rows"></param>行数
/// <param name="cols"></param>列数
private void setBound(Vector2 bound)
{
m_Rect.sizeDelta = new Vector2(bound.y * CellRect.x, bound.x * CellRect.y);
}

public float MaxPrevPos
{
get
{
float result;
Vector2 max = getRectByNum(m_Datas.Count);
if(direction == Direction.Horizontal)
{
result = max.y - m_Page.y;
}
else
{
result = max.x - m_Page.x;
}
return result * CellScale;
}
}
public float scale { get { return direction == Direction.Horizontal ? 1f : -1f; } }
void Update()
{
while (scale * DirectionPos - m_PrevPos < -CellScale * 2)
{
if (m_PrevPos <= -MaxPrevPos) return;

m_PrevPos -= CellScale;

List<RectTransform> range = m_InstantiateItems.GetRange(0, PageScale);
m_InstantiateItems.RemoveRange(0, PageScale);
m_InstantiateItems.AddRange(range);
for (int i = 0; i < range.Count; i++)
{
moveItemToIndex(m_CurrentIndex * PageScale + m_InstantiateItems.Count + i, range[i]);
}
m_CurrentIndex++;
}

while (scale * DirectionPos - m_PrevPos > -CellScale)
{
if (Mathf.RoundToInt(m_PrevPos) >= 0) return;

m_PrevPos += CellScale;

m_CurrentIndex--;

if (m_CurrentIndex < 0) return;

List<RectTransform> range = m_InstantiateItems.GetRange(m_InstantiateItems.Count - PageScale, PageScale);
m_InstantiateItems.RemoveRange(m_InstantiateItems.Count - PageScale, PageScale);
m_InstantiateItems.InsertRange(0, range);
for (int i = 0; i < range.Count; i++)
{
moveItemToIndex(m_CurrentIndex * PageScale + i, range[i]);
}
}
}

private void moveItemToIndex(int index, RectTransform item)
{
item.anchoredPosition = getPosByIndex(index);
updateItem(index, item.gameObject);
}

private Vector2 getPosByIndex(int index)
{
float x, y;
if(direction == Direction.Horizontal)
{
x = index % m_Page.x;
y = Mathf.FloorToInt(index / m_Page.x);
}
else
{
x = Mathf.FloorToInt(index / m_Page.y);
y = index % m_Page.y;
}

return new Vector2(y * CellRect.x, -x * CellRect.y);
}

private void updateItem(int index, GameObject item)
{
item.SetActive(index < m_Datas.Count);

if(item.activeSelf)
{
UILoopItem lit = item.GetComponent<UILoopItem>();
lit.UpdateItem(index, item);
lit.Data(m_Datas[index]);
}
}
}