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Unity无限滚动列表

小紫苏 人气:0

无限滚动复用列表

Demo展示

前言

游戏中有非常多的下拉滚动菜单,比如成就列表,任务列表,以及背包仓库之类;如果列表内容非常丰富,会占用大量内存,这篇无限滚动复用ScrollView就是解决这种问题;还可以用来做朋友圈,聊天等;

一般情况,ScrollView中每个Item的大小是一直的,使用ContentSizeFillter组件足够解决大部分问题;

如果每个Item大小不一致,问题就复杂起来,需要做滚动位置判断,我这里做了大小适应;

设计思路

1.将数据部分和滚动逻辑部分分离开,数据设计成泛型类;

2.在ScrollView组件上添加ScrollView脚本,控制Item的添加和删除,分为头部和尾部;

3.在每个Item上添加ScrollItem脚本,重写更新数据方法,同时监听自身是否为头部或者尾部;

4.如果为头部或者尾部,且超界通过委托调用ScrollView脚本中的添加或删除Item方法;

关键基类

1.ScrollData

负责整个列表的数据管理,分为总数据和现实数据两个链表,增删查改方法;泛型类方便复用;

这里使用LinkedList方便查找并返回头尾节点;

全部代码:

public class ScrollData<T>
{
    public List<T> allDatas;
    public LinkedList<T> curDatas;
    
    public ScrollData()
    {
        allDatas = new List<T>();
        curDatas = new LinkedList<T>();
        //加载数据;
    }
    //获取头数据
    public T GetHeadData()
        if(allDatas.Count == 0)
            return default(T);
        if (curDatas.Count == 0)
        {
            T head = allDatas[0];
            curDatas.AddFirst(head);
            return head;
        }
        T t = curDatas.First.Value;
        int index = allDatas.IndexOf(t);
        if (index != 0)
            T head = allDatas[index - 1];
        return default(T);
    //移出头数据
    public bool RemoveHeadData()
        if (curDatas.Count == 0 || curDatas.Count == 1)
            return false;
        curDatas.RemoveFirst();
        return true;
    //获取尾部数据
    public T GetEndData()
        if (allDatas.Count == 0)
            T end = allDatas[0];
            curDatas.AddLast(end);
            return end;
        T t = curDatas.Last.Value;
        
        if (index != allDatas.Count - 1)
            T end = allDatas[index + 1];
         
    //移出尾部数据
    public bool RemoveEndData()
        curDatas.RemoveLast();
    //添加数据,通过数组
    public void AddData(T[] t)
        allDatas.AddRange(t);
    //添加数据,通过链表
    public void AddData(List<T> t)
        allDatas.AddRange(t.ToArray()); 
    //添加单条数据
    public void AddData(T t)
        allDatas.Insert(0,t);
        curDatas.AddFirst(t);
    //情况当前显示节点
    public void ClearCurData()
        curDatas.Clear();
    //获取当前显示链表的第一个数据在总数据中的下标
    public int GetFirstIndex()
        return allDatas.IndexOf(t);
}

2.ScrollView

关键字段:

scrollItemGo	//每个Item的预制体
content			//scrollRect下的Content
spacing			//每个Item的间隔
isStart			//是否第一次加载

方法:

GetChildItem;

1.获取一个Item的预制体,先从content的子物体中寻找active为false的物体,如果没有则根据scrollItemGo克隆一个;

2.创建新Item时,获取ScrollItem组件,赋值其中的参数(四个委托),并初始化;

OnAddHead;OnRemoveHead;OnAddEnd;OnRemoveEnd;

委托方法:

1.调用ScrollData中GetHeadData方法,获得头数据;

2.找到content中第一个节点;

3.调用GetChildItem方法获得item的实例;

4.SetAsFirstSibling,将实例设置为首节点,同时调用RefreshData,刷新数据;

5.根据item 的宽度做自适应(item大小相同,只选挂载ContentSizeFitter);

全部代码:

public class ScrollView : MonoBehaviour
{
    public GameObject scrollItemGo;
    private RectTransform content;
    
    [SerializeField]
    private float spacing;
    private bool isStart = true;
    void Start()
    {
        content = this.GetComponent<ScrollRect>().content;
        spacing = 15;
        OnAddHead();
    }
    private GameObject GetChildItem()
        //查找是否有未回收的子节点
        for (int i = 0; i < content.childCount; ++i)
        {
            GameObject tempGo = content.GetChild(i).gameObject;
            if (!tempGo.activeSelf)
            {
                tempGo.SetActive(true);
                return tempGo;
            }
        }
        //无创建新的
        GameObject childItem = GameObject.Instantiate<GameObject>(scrollItemGo,content.transform);
        ScrollViewItem scrollItem = childItem.GetComponent<ScrollViewItem>();
        if (scrollItem == null)
            scrollItem = childItem.AddComponent<ScrollViewItem>();
        
        scrollItem.onAddHead += OnAddHead;
        scrollItem.onRemoveHead += OnRemoveHead;
        scrollItem.onAddEnd += OnAddEnd;
        scrollItem.onRemoveEnd += OnRemoveEnd;
        scrollItem.Init();
        childItem.GetComponent<RectTransform>().anchorMin = new Vector2(0.5f, 1);
        childItem.GetComponent<RectTransform>().anchorMax = new Vector2(0.5f, 1);
        childItem.GetComponent<RectTransform>().pivot = new Vector2(0, 1);
        childItem.transform.localScale = Vector3.one;
        childItem.transform.localPosition = Vector3.zero;
        //-----设置宽高——加载数据 
        return childItem;
    private void OnAddHead()
        Data data = this.GetComponent<Test>().scrollData.GetHeadData();
        if (data != null)
            Transform first = FindFirst();
            //----first 不为 数据头---在data中做了
            GameObject obj = GetChildItem();
            obj.GetComponent<ScrollViewItem>().RefreshData(data);
            obj.transform.SetAsFirstSibling();
            RectTransform objRect = obj.GetComponent<RectTransform>();
            float height = objRect.sizeDelta.y;
            
            if (first != null)
                obj.transform.localPosition = first.localPosition + new Vector3(0, height + spacing, 0);
            if (isStart)
                content.sizeDelta += new Vector2(0, height + spacing);
                isStart = false;
    private void OnRemoveHead()
        var scrollData = this.GetComponent<Test>().scrollData;
        if (scrollData.RemoveHeadData())
            Transform tf = FindFirst();
            if (tf != null)
                tf.gameObject.SetActive(false);
    private void OnAddEnd()
        Data data = this.GetComponent<Test>().scrollData.GetEndData();
            Transform end = FindEnd();
            //----end 不为 数据尾在data中做了
            obj.transform.SetAsLastSibling();
            float height = end.GetComponent<RectTransform>().sizeDelta.y;
            if (end != null)
                obj.transform.localPosition = end.localPosition - new Vector3(0, height + spacing, 0);
            //是否增加content高度
            if (IsAddContentH(obj.transform))
                float h = obj.GetComponent<RectTransform>().sizeDelta.y;
                content.sizeDelta += new Vector2(0, h + spacing);
    private void OnRemoveEnd()
        if (scrollData.RemoveEndData())
            Transform tf = FindEnd();
    private Transform FindFirst()
            if (content.GetChild(i).gameObject.activeSelf)
                return content.GetChild(i);
        return null;
    private Transform FindEnd()
        for (int i = content.childCount - 1; i >= 0; --i)
    private bool IsAddContentH(Transform tf)
        Vector3[] rectC = new Vector3[4];
        Vector3[] contentC = new Vector3[4];
        tf.GetComponent<RectTransform>().GetWorldCorners(rectC);
        content.GetWorldCorners(contentC);
        if (rectC[0].y < contentC[0].y)
            return true;
        return false;
}

3.ScrollItem

关键字段:四个委托

public Action onAddHead;
public Action onRemoveHead;
public Action onAddEnd;
public Action onRemoveEnd;

关键方法:

OnRecyclingItem;

1.判断自身是否为头尾节点;

2.判断自身是否超界,超界需要隐藏自身;

3.判断自身与边界距离,是否添加节点;

关键API:

RectTransform.GetWorldCorners(Vector3[4])

获取UI对象四个顶点的世界坐标,下标对应的位置;

全部代码:

public class ScrollViewItem : MonoBehaviour
{
    private RectTransform viewRect;
    private RectTransform rect;
    [SerializeField]
    private float viewStart;
    [SerializeField]
    private float viewEnd;
    [SerializeField]
    private Vector3[] rectCorners;
    public Action onAddHead;
    public Action onRemoveHead;
    public Action onAddEnd;
    public Action onRemoveEnd;
    public Text nameT;
    public Text inputT;
    void Start()
    {
        Init();
    }
    public void Init()
    {
        viewRect = transform.parent.parent.GetComponent<RectTransform>();
        rect = this.GetComponent<RectTransform>();
        rectCorners = new Vector3[4];
        viewRect.GetWorldCorners(rectCorners);
        viewStart = rectCorners[1].y;
        viewEnd = rectCorners[0].y;
    }
    void Update()
    {
        OnRecyclingItem();
    }
    //超界变false;
    private void OnRecyclingItem()
    {
        rect = this.GetComponent<RectTransform>();
        rectCorners = new Vector3[4];
        rect.GetWorldCorners(rectCorners);
        if (IsFirst())
        {
            if (rectCorners[0].y > viewStart)
            {
                //隐藏头节点  
                if (onRemoveHead != null)
                    onRemoveHead();
            }
            if (rectCorners[1].y < viewStart)
            {
                //添加头节点-头节点不为数据起始点
                if (onAddHead != null)
                    onAddHead();
            }
        }
        if (IsLast())
        {
            if (rectCorners[0].y > viewEnd)
            {
                //添加尾节点-尾节点不为数据末尾 
                if (onAddEnd != null)
                    onAddEnd();
            }
            if (rectCorners[1].y < viewEnd)
            {
                //隐藏尾节点 
                if (onRemoveEnd != null)
                    onRemoveEnd();
            }
        }
    }
    private bool IsFirst()
    {
        for (int i = 0; i < transform.parent.childCount; ++i)
        {
            Transform tf = transform.parent.GetChild(i);
            if (tf.gameObject.activeSelf)
            {
                if (tf == this.transform)
                {
                    return true;
                }
                break;
            }
        }
        return false;
    }
    private bool IsLast()
    {
        for (int i = transform.parent.childCount-1; i >= 0 ; i--)
        {
            Transform tf = transform.parent.GetChild(i);
            if (tf.gameObject.activeSelf)
            {
                if (tf == this.transform)
                {
                    return true;
                }
                break;
            }
        }
        return false;
    }
    public bool IsInView()
    {
        rect = this.GetComponent<RectTransform>();
        rect.GetWorldCorners(rectCorners);
        if (rectCorners[1].y > viewEnd || rectCorners[0].y < viewStart)
            return false;
        return true;
    }
    public void RefreshData(Data da)
    {
        nameT.text = da.name;
        inputT.text = da.text;
      
        Vector2 oldSize = rect.sizeDelta;
        rect.sizeDelta = new Vector2(oldSize.x, 200 + da.h);
    }
}

测试类

初始化数据,随机4中宽度的item;

void InitData()
{
    int[] hArr = new int[4];
    hArr[0] = 0;
    hArr[1] = 190;
    hArr[2] = 190 * 2;
    hArr[3] = 190 * 3;
    for (int i = 0; i < 30; ++i)
    {
        Data da = new Data();
        da.name = "小紫苏" + i.ToString();
        da.text = "000000" + i.ToString();
        int index = UnityEngine.Random.Range(0, 3);
        da.h = hArr[index];
        scrollData.allDatas.Add(da);
    }
}

添加三个按钮,及相应的响应方法;

1.添加20组数据

private void AddData()
{
    int[] hArr = new int[4];
    hArr[0] = 0;
    hArr[1] = 190;
    hArr[2] = 190 * 2;
    hArr[3] = 190 * 3;
    Data[] newData = new Data[20];
    for (int i = 0; i < 20; ++i)
    {
        Data da = new Data();
        da.name = "小紫苏" + i.ToString();
        da.text = "000000" + i.ToString();
        int index = UnityEngine.Random.Range(0, 3);
        da.h = hArr[index];
        newData[i] = da;
    }
    scrollDat

回到顶部或底部需要有过程,因此需要在update中运行,也可以用插值;

2.回到顶部

private void OnGoHead()
{
    if (isGoHead)
        isGoHead = false;
    else
        isGoHead = true;
}
private void OnGoLast()
{
    if (isGoLast)
        isGoLast = false;
    else
        isGoLast = true;
}

3.回到底部

private void GoHead()
{
    if (!isGoHead)
        return;
    
    float curPos = scroll.verticalNormalizedPosition;
    if (curPos != 1)
    {
        curPos += 0.01f;
        if (curPos >= 1)
        {
            curPos = 1;
            isGoHead = false;
        }
        scroll.verticalNormalizedPosition = curPos;
    }
}
private void GoLast()
{
    if (!isGoLast)
        return;
    float curPos = scroll.verticalNormalizedPosition;
    if (curPos != 0)
    {
        curPos -= 0.01f;
        if (curPos <= 0)
        {
            curPos = 0;
            isGoLast = false;
        }
        scroll.verticalNormalizedPosition = curPos;
    }
}

坑点

1.ScrollView回滚设置延迟;

回滚判断是通过verticalNormalizedPosition的API,更改这个值后需要间隔一帧才会修改,因为可能导致判断两次;

解决方法,延迟调用1s——Invoke;

2.锚点设置;

锚点的设置以及UI的自适应会直接影响项目回滚的方向和位置;

大部分位置出错都是因为锚点设置错误;

3.数据需要网络请求,自适应会失效;

网络数据一般都是异步,所以判断会做多次,因此数据上要求提前计算好item的宽度;

项目工程我上传到Gitee,可自行下载学习;https://gitee.com/small-perilla/scroll-view

以上是我对滚动复用组件的总结,如果有更好的意见,欢迎给作者评论留言;

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