因为在界面中大量使用了 Outline 以及界面复杂度较高，在邮件 等需要超长滚动列表的界面，就会十分卡顿。既然美术与策划同学不能妥协，那就来优化代码。
按照滚动区域的属性，展示给玩家看的只是一小块区域，比如列表中有100封邮件，其实只要显示个七八封就够了，剩下的，在向上滑动的时候，把第一排移动到最后一排，替换内容。
这样做能提高绘制效率，但是因为是在滑动的时候动画创建，所以会稍有卡顿，所以只适用于超长列表的情况使用，至于到底多长需要自己取舍。
转自http://blog.csdn.net/huutu http://www.thisisgame.com.cn
下面是代码
/************************** * 文件名:InfinityGridLayoutGroup.cs; * 文件描述:无限滚动GridLayoutGroup,动态创建滚动Item; * 实现无限滚动，需要的最少的child数量。屏幕上能看到的+一行看不到的，比如我在屏幕上能看到 2 行，每一行 2 个。则这个值为 2行*2个 + 1 行* 2个 = 6个。 * 创建日期:2016/05/31; * Author:ThisisGame; * Page:https://github.com/ThisisGame/InfinityGridLayoutGroup ***************************/using UnityEngine;using System.Collections;using UnityEngine.UI;using System.Collections.Generic;[RequireComponent(typeof(GridLayoutGroup))][RequireComponent(typeof(ContentSizeFitter))]public class InfinityGridLayoutGroup : MonoBehaviour { [SerializeField] int minAmount = 0;//实现无限滚动，需要的最少的child数量。屏幕上能看到的+一行看不到的，比如我在屏幕上能看到 2 行，每一行 2 个。则这个值为 2行*2个 + 1 行* 2个 = 6个。 RectTransform rectTransform; GridLayoutGroup gridLayoutGroup; ContentSizeFitter contentSizeFitter; ScrollRect scrollRect; List<RectTransform> children=new List<RectTransform>(); Vector2 startPosition; int amount = 0; public delegate void UpdateChildrenCallbackDelegate(int index, Transform trans); public UpdateChildrenCallbackDelegate updateChildrenCallback = null; int realIndex = -1; int realIndexUp = -1; //从下往上; bool hasInit = false; Vector2 gridLayoutSize; Vector2 gridLayoutPos; Dictionary<Transform, Vector2> childsAnchoredPosition = new Dictionary<Transform, Vector2>(); Dictionary<Transform, int> childsSiblingIndex = new Dictionary<Transform, int>(); // Use this for initialization void Start () { //StartCoroutine(InitChildren()); } IEnumerator InitChildren() { yield return 0; if (!hasInit) { //获取Grid的宽度; rectTransform = GetComponent<RectTransform>(); gridLayoutGroup = GetComponent<GridLayoutGroup>(); gridLayoutGroup.enabled = false; contentSizeFitter = GetComponent<ContentSizeFitter>(); contentSizeFitter.enabled = false; gridLayoutPos = rectTransform.anchoredPosition; gridLayoutSize = rectTransform.sizeDelta; //注册ScrollRect滚动回调; scrollRect = transform.parent.GetComponent<ScrollRect>(); scrollRect.onValueChanged.AddListener((data) => { ScrollCallback(data); }); //获取所有child anchoredPosition 以及 SiblingIndex; for (int index = 0; index < transform.childCount; index++) { Transform child=transform.GetChild(index); RectTransform childRectTrans= child.GetComponent<RectTransform>(); childsAnchoredPosition.Add(child, childRectTrans.anchoredPosition); childsSiblingIndex.Add(child, child.GetSiblingIndex()); } } else { rectTransform.anchoredPosition = gridLayoutPos; rectTransform.sizeDelta = gridLayoutSize; children.Clear(); realIndex = -1; realIndexUp = -1; //children重新设置上下顺序; foreach (var info in childsSiblingIndex) { info.Key.SetSiblingIndex(info.Value); } //children重新设置anchoredPosition; for (int index = 0; index < transform.childCount; index++) { Transform child = transform.GetChild(index); RectTransform childRectTrans = child.GetComponent<RectTransform>(); if (childsAnchoredPosition.ContainsKey(child)) { childRectTrans.anchoredPosition = childsAnchoredPosition[child]; } else { Debug.LogError("childsAnchoredPosition no contain "+child.name); } } } //获取所有child; for (int index = 0; index < transform.childCount; index++) { Transform trans = transform.GetChild(index); trans.gameObject.SetActive(true); children.Add(transform.GetChild(index).GetComponent<RectTransform>()); //初始化前面几个; UpdateChildrenCallback(children.Count - 1, transform.GetChild(index)); } startPosition = rectTransform.anchoredPosition; realIndex = children.Count - 1; //Debug.Log( scrollRect.transform.TransformPoint(Vector3.zero)); // Debug.Log(transform.TransformPoint(children[0].localPosition)); hasInit = true; //如果需要显示的个数小于设定的个数; for (int index = 0; index < minAmount; index++) { children[index].gameObject.SetActive(index < amount); } if (gridLayoutGroup.constraint == GridLayoutGroup.Constraint.FixedColumnCount) { //如果小了一行，则需要把GridLayout的高度减去一行的高度; int row = (minAmount - amount) / gridLayoutGroup.constraintCount; if (row > 0) { rectTransform.sizeDelta -= new Vector2(0, (gridLayoutGroup.cellSize.y + gridLayoutGroup.spacing.y) * row); } } else { //如果小了一列，则需要把GridLayout的宽度减去一列的宽度; int column = (minAmount - amount) / gridLayoutGroup.constraintCount; if (column > 0) { rectTransform.sizeDelta -= new Vector2((gridLayoutGroup.cellSize.x + gridLayoutGroup.spacing.x) * column, 0); } } } // Update is called once per frame void Update () { } void ScrollCallback(Vector2 data) { UpdateChildren(); } void UpdateChildren() { if (transform.childCount < minAmount) { return; } Vector2 currentPos = rectTransform.anchoredPosition; if (gridLayoutGroup.constraint == GridLayoutGroup.Constraint.FixedColumnCount) { float offsetY = currentPos.y - startPosition.y; if (offsetY > 0) { //向上拉，向下扩展; { if (realIndex >= amount - 1) { startPosition = currentPos; return; } float scrollRectUp = scrollRect.transform.TransformPoint(Vector3.zero).y; Vector3 childBottomLeft = new Vector3(children[0].anchoredPosition.x, children[0].anchoredPosition.y - gridLayoutGroup.cellSize.y, 0f); float childBottom = transform.TransformPoint(childBottomLeft).y; if (childBottom >= scrollRectUp) { //Debug.Log("childBottom >= scrollRectUp"); //移动到底部; for (int index = 0; index < gridLayoutGroup.constraintCount; index++) { children[index].SetAsLastSibling(); children[index].anchoredPosition = new Vector2(children[index].anchoredPosition.x, children[children.Count - 1].anchoredPosition.y - gridLayoutGroup.cellSize.y - gridLayoutGroup.spacing.y); realIndex++; if (realIndex > amount - 1) { children[index].gameObject.SetActive(false); } else { UpdateChildrenCallback(realIndex, children[index]); } } //GridLayoutGroup 底部加长; rectTransform.sizeDelta += new Vector2(0, gridLayoutGroup.cellSize.y + gridLayoutGroup.spacing.y); //更新child; for (int index = 0; index < children.Count; index++) { children[index] = transform.GetChild(index).GetComponent<RectTransform>(); } } } } else { //Debug.Log("Drag Down"); //向下拉，下面收缩; if (realIndex + 1 <= children.Count) { startPosition = currentPos; return; } RectTransform scrollRectTransform = scrollRect.GetComponent<RectTransform>(); Vector3 scrollRectAnchorBottom = new Vector3(0, -scrollRectTransform.rect.height - gridLayoutGroup.spacing.y, 0f); float scrollRectBottom = scrollRect.transform.TransformPoint(scrollRectAnchorBottom).y; Vector3 childUpLeft = new Vector3(children[children.Count - 1].anchoredPosition.x, children[children.Count - 1].anchoredPosition.y, 0f); float childUp = transform.TransformPoint(childUpLeft).y; if (childUp < scrollRectBottom) { //Debug.Log("childUp < scrollRectBottom"); //把底部的一行 移动到顶部 for (int index = 0; index < gridLayoutGroup.constraintCount; index++) { children[children.Count - 1 - index].SetAsFirstSibling(); children[children.Count - 1 - index].anchoredPosition = new Vector2(children[children.Count - 1 - index].anchoredPosition.x, children[0].anchoredPosition.y + gridLayoutGroup.cellSize.y + gridLayoutGroup.spacing.y); children[children.Count - 1 - index].gameObject.SetActive(true); UpdateChildrenCallback(realIndex - children.Count - index, children[children.Count - 1 - index]); } realIndex -= gridLayoutGroup.constraintCount; //GridLayoutGroup 底部缩短; rectTransform.sizeDelta -= new Vector2(0, gridLayoutGroup.cellSize.y + gridLayoutGroup.spacing.y); //更新child; for (int index = 0; index < children.Count; index++) { children[index] = transform.GetChild(index).GetComponent<RectTransform>(); } } } } else { float offsetX = currentPos.x - startPosition.x; if (offsetX < 0) { //向左拉，向右扩展; { if (realIndex >= amount - 1) { startPosition = currentPos; return; } float scrollRectLeft = scrollRect.transform.TransformPoint(Vector3.zero).x; Vector3 childBottomRight = new Vector3(children[0].anchoredPosition.x+ gridLayoutGroup.cellSize.x, children[0].anchoredPosition.y, 0f); float childRight = transform.TransformPoint(childBottomRight).x; // Debug.LogError("childRight=" + childRight); if (childRight <= scrollRectLeft) { //Debug.Log("childRight <= scrollRectLeft"); //移动到右边; for (int index = 0; index < gridLayoutGroup.constraintCount; index++) { children[index].SetAsLastSibling(); children[index].anchoredPosition = new Vector2(children[children.Count - 1].anchoredPosition.x + gridLayoutGroup.cellSize.x + gridLayoutGroup.spacing.x, children[index].anchoredPosition.y); realIndex++; if (realIndex > amount - 1) { children[index].gameObject.SetActive(false); } else { UpdateChildrenCallback(realIndex, children[index]); } } //GridLayoutGroup 右侧加长; rectTransform.sizeDelta += new Vector2(gridLayoutGroup.cellSize.x + gridLayoutGroup.spacing.x,0); //更新child; for (int index = 0; index < children.Count; index++) { children[index] = transform.GetChild(index).GetComponent<RectTransform>(); } } } } else { //Debug.Log("Drag Down"); //向右拉，右边收缩; if (realIndex + 1 <= children.Count) { startPosition = currentPos; return; } RectTransform scrollRectTransform = scrollRect.GetComponent<RectTransform>(); Vector3 scrollRectAnchorRight = new Vector3(scrollRectTransform.rect.width + gridLayoutGroup.spacing.x, 0, 0f); float scrollRectRight = scrollRect.transform.TransformPoint(scrollRectAnchorRight).x; Vector3 childUpLeft = new Vector3(children[children.Count - 1].anchoredPosition.x, children[children.Count - 1].anchoredPosition.y, 0f); float childLeft = transform.TransformPoint(childUpLeft).x; if (childLeft >= scrollRectRight) { //Debug.LogError("childLeft > scrollRectRight"); //把右边的一行 移动到左边; for (int index = 0; index < gridLayoutGroup.constraintCount; index++) { children[children.Count - 1 - index].SetAsFirstSibling(); children[children.Count - 1 - index].anchoredPosition = new Vector2(children[0].anchoredPosition.x - gridLayoutGroup.cellSize.x - gridLayoutGroup.spacing.x,children[children.Count - 1 - index].anchoredPosition.y); children[children.Count - 1 - index].gameObject.SetActive(true); UpdateChildrenCallback(realIndex - children.Count - index, children[children.Count - 1 - index]); } //GridLayoutGroup 右侧缩短; rectTransform.sizeDelta -= new Vector2(gridLayoutGroup.cellSize.x + gridLayoutGroup.spacing.x, 0); //更新child; for (int index = 0; index < children.Count; index++) { children[index] = transform.GetChild(index).GetComponent<RectTransform>(); } realIndex -= gridLayoutGroup.constraintCount; } } } startPosition = currentPos; } void UpdateChildrenCallback(int index,Transform trans) { if (updateChildrenCallback != null) { updateChildrenCallback(index, trans); } } /// <summary> /// 设置总的个数; /// </summary> /// <param name="count"></param> public void SetAmount(int count) { amount = count; StartCoroutine(InitChildren()); }}使用方法：
和GridLayoutGroup 同时使用，设置固定显示的子物体。
使用效果
转自http://blog.csdn.net/huutu http://www.thisisgame.com.cn
工程下载
https://github.com/ThisisGame/InfinityGridLayoutGroup