Unity 圆形循环复用滚动列表

一.在上一篇垂直循环复用滚动列表的基础上，扩展延申了圆形循环复用滚动列表。实现此效果需要导入垂直循环复用滚动列表里面的类。

1.基础类

using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;
using UnityEngine.UIElements;

/// <summary>
/// 环形的网格布局；
/// 让子对象摆成一个环形；
/// </summary>
public class CricleGrid : MonoBehaviour
{
    /// <summary>
    /// 是否是自动刷新模式，否则的话需要手动调用刷新；
    /// </summary>
    public bool IsAutoRefresh = true;

    /// <summary>
    /// 是否发生过改变；
    /// </summary>
    private bool IsChanged = false;
    /// <summary>
    /// 上一次检查的数量；
    /// </summary>
    int LastCheckCount = 0;

    /// <summary>
    /// Update每帧调用一次
    /// </summary>
    void Update()
    {
        检查是否需要自动刷新；
        if (!IsAutoRefresh)
            return;

        if (!IsChanged)
        {
            //检测子物体有没有被改变；
            GetChidList();
            int length = ListRect.Count;
            if (length != LastCheckCount)
            {
                LastCheckCount = length;
                IsChanged = true;
            }
            //此时刷新大小和位置；
            if (IsChanged)
                ResetSizeAndPos();
        }
        else
            RefreshAll();
    }

    private void OnValidate()
    {
        //编辑器下每一次更改需要实时刷新；
        RefreshAll();
    }

    /// <summary>
    /// 全部刷新；
    /// </summary>
    public void RefreshAll()
    {
        GetChidList();
        ResetSizeAndPos();
    }

    /// <summary>
    /// 当下激活的Rect；
    /// </summary>
    public List<RectTransform> ListRect = new List<RectTransform>(4);
    List<RectTransform> tempListRect = new List<RectTransform>(4);

    /// <summary>
    /// 获取父节点为本身的子对象
    /// </summary>
    void GetChidList()
    {
        ListRect.Clear();
        GetComponentsInChildren(false, tempListRect);
        int length = tempListRect.Count;
        for (int i = 0; i < length; i++)
        {
            var r = tempListRect[i];
            if (r.transform.parent != transform) continue;
            ListRect.Add(r);
        }
    }

    /// <summary>
    /// 网格大小；
    /// </summary>
    public Vector2 CellSize = new Vector2();

    /// <summary>
    /// 半径；
    /// </summary>
    public float Radius = 1;

    /// <summary>
    /// 起始角度；
    /// </summary>
    [Range(0f, 360f)]
    [SerializeField]
    float m_StartAngle = 30;

    /// <summary>
    /// 起始角度；
    /// </summary>
    public float StartAngle
    {
        get { return m_StartAngle; }
        set
        {
            m_StartAngle = value;
            IsChanged = true;
        }
    }

    /// <summary>
    /// 间隔角度；
    /// </summary>
    [Range(0f, 360f)]
    [SerializeField]
    float m_Angle = 30;

    /// <summary>
    /// 间隔角度；
    /// </summary>
    public float Angle
    {
        get { return m_Angle; }
        set
        {
            m_Angle = value;
            IsChanged = true;
        }
    }
    public Dictionary<int, CricleScrollItemPosData> itemPosDic = new();
    public List<CricleScrollItemPosData> itemPosList = new();
    /// <summary>
    /// 重新将字节点设置大小；
    /// </summary>
    public void ResetSizeAndPos()
    {
        int length = ListRect.Count;
        for (int i = 0; i < length; i++)
        {
            var tran = ListRect[i];
            tran.sizeDelta = CellSize;
            var v = GerCurPosByIndex(i);
            tran.anchoredPosition = new Vector2(v.x,v.y);
            tran.localEulerAngles = new Vector3(0,0, v.z);
        }
    }

    /// <summary>
    /// 返回第几个子对象应该所在的相对位置；
    /// </summary>
    public Vector3 GerCurPosByIndex(int index)
    {
        //1、先计算间隔角度：(弧度制)
        float totalAngle = Mathf.Deg2Rad * (index * Angle + m_StartAngle);
        //2、计算位置
        Vector3 Pos = new Vector2(Radius * Mathf.Cos(totalAngle), Mathf.Sin(totalAngle) * Radius);
        Pos.z = index * Angle + m_StartAngle + 180;
        return Pos;
    }

    public ScrollRect scrollRect;
    public List<object> list = new();
    public GameObject item;
    private List<CustomScrollItemMono> scrollTestItems = new();
    private int startIndex;
    private int endIndex;
    private int showItemCount = 10;



    private void InitItemsPos() 
    {
        int n = (int)(360f / Angle);
        for (int i = 0; i < list.Count; i++)
        {
            var v = GerCurPosByIndex(i);
            CricleScrollItemPosData data = new CricleScrollItemPosData();
            data.AnchoredPosition = new Vector3(v.x, v.y);
            data.LocalEulerAngles = new Vector3(0, 0, v.z);
            itemPosDic.Add(i, data);
            itemPosList.Add(data);
            //if (i < n)
            //{
            //    var v = GerCurPosByIndex(i);
            //    CricleScrollItemPosData data = new CricleScrollItemPosData();
            //    data.AnchoredPosition = new Vector3(v.x, v.y);
            //    data.LocalEulerAngles = new Vector3(0, 0, v.z);
            //    itemPosDic.Add(i, data);
            //    itemPosList.Add(data);
            //}
            //else 
            //{
            //    int temp = i % n;
            //    int m = (i + 1) / n;
            //    CricleScrollItemPosData d = new CricleScrollItemPosData();
            //    d.AnchoredPosition = itemPosDic[temp].AnchoredPosition;
            //    d.LocalEulerAngles.z += itemPosDic[temp].LocalEulerAngles.z + 360 * m;
            //    itemPosDic.Add(i, d);
            //    itemPosList.Add(d);
            //}
        }
        Debug.Log($"InitItemsPos ");
    }

    private void InitShowItems()
    {
        for (int i = 0; i < showItemCount; i++)
        {
            GameObject obj = Instantiate(item, transform);
            obj.transform.name = i.ToString();
            obj.SetActive(true);
            CustomScrollItemMono testItem = obj.GetComponent<CustomScrollItemMono>();
            testItem.Init(i, list[i]);
            scrollTestItems.Add(testItem);
        }
        item.SetActive(false);
    }



    private float eulerAnglersZ;
    private float preA = 1;
    public ScrollRect ScrollRect;
    private RectTransform Content;

    /// <summary>
    /// 用这个初始化
    /// </summary>
    void Start()
    {
        for (int i = 0; i < 100; i++)
        {
            list.Add(new ScrollTestData() { ID = i });
        }
        Content = ScrollRect.content;
        Content.sizeDelta = new Vector2(500, (100 * Angle / 360 + StartAngle % 360 / 360f) * 2 * Mathf.PI * Radius);
        InitItemsPos();
        InitShowItems();
        RefreshAll();
    }

    private void Awake()
    {
        scrollRect.horizontal = false;
        scrollRect.vertical = true;
        scrollRect.onValueChanged.AddListener((value) =>
        {
            float offset = Mathf.Abs(preA - value.y);
            float aa = (offset) * ((100 - 6) * Angle);
            if (scrollRect.velocity.y > 0) //手指上滑 
            {
                transform.localEulerAngles -= new Vector3(0,0, aa);
                eulerAnglersZ += aa;
            }
            else if (scrollRect.velocity.y < 0)//手指下滑 
            {
                transform.localEulerAngles += new Vector3(0, 0, aa);
                eulerAnglersZ -= aa;
            }
            preA = value.y;
 
            for (int i = startIndex; i < itemPosList.Count; i++)
            {
                if (i + 1 < itemPosList.Count)
                {
                    if (scrollRect.velocity.y > 0)//手指上滑 
                    {
                        var targetY = itemPosList[i + 1].LocalEulerAngles.z - 180;
                        //Debug.Log($"ccc y {y} targetY {targetY} startIndex {startIndex} Z {transform.localEulerAngles.z}");
                        if (eulerAnglersZ + StartAngle >= targetY)
                        {
                            startIndex = i + 1;
                            endIndex = startIndex + showItemCount - 1;
                            break;
                        }
                    }
                    else if (scrollRect.velocity.y < 0)//手指下滑
                    {
                        if (startIndex > 0 && startIndex < itemPosDic.Count)
                        {
                            var targetY = itemPosDic[startIndex].LocalEulerAngles.z - 180;
                            if (eulerAnglersZ + StartAngle <= targetY)
                            {
                                startIndex = i - 1;
                                endIndex = startIndex + showItemCount - 1;
                                break;
                            }
                        }
                    }
                }
            }
            //Debug.Log($"bbb startIndex {startIndex} endIndex {endIndex}");
            if (startIndex > 100 - showItemCount) 
            {
                startIndex = 100 - showItemCount;
            }
            if (endIndex >= itemPosDic.Count) { return; }
            int index = 0;
            for (int i = startIndex; i < endIndex + 1; i++)
            {
                if (index < scrollTestItems.Count && i < itemPosDic.Count)
                {
                    var item = scrollTestItems[index];
                    item.Init(i, list[i]);
                    var rect = item.gameObject.GetComponent<RectTransform>();
                    rect.anchoredPosition3D = itemPosDic[i].AnchoredPosition;
                    rect.localEulerAngles = itemPosDic[i].LocalEulerAngles;
                    index += 1;
                }
            }
        });
    }


    public class CricleScrollItemPosData
    {
        public Vector3 AnchoredPosition;
        public Vector3 LocalEulerAngles;
    }

}

2.UI目录