吸附式滚动列表

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using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;/// <summary>
/// 吸附式滚动列表
/// </summary>
public class PageAdsorbScrollview : MonoBehaviour, IEndDragHandler, IBeginDragHandler
{public enum ScrollType{Horizontal,Vertical}private ScrollRect scrollRect;private RectTransform content;private GridLayoutGroup gridLayoutGroup;private int pageCount;private float[] pagesData; //位置private float timer = 0; //吸附计时器private float startMovePos; //开始移动的位置private Vector2 startMovePosV2; //开始移动的位置private int currentIndex = 0; //当前所处页数private bool isMoving = false; //是否正在吸附中private bool isDraging = false; //是否在拖动中private Vector2 beginDragPointerPos; //开始拖动时的位置private float autotimer = 0; //自动计时器private float finalPosOffsetBackup = 0f;private Vector2 originalCellSize;[Header("滑动类型")]public ScrollType scrollType = ScrollType.Vertical;[Header("吸附速度"), Range(0f, 50f)]public float moveSpeed = 5f;[Header("终点位置偏移（0为最终吸附到顶部）")]public float finalPosOffset = 0f;[Header("界限偏移（0为五五分判定，>0更容易拖动，<0更难拖动）")]public float distanceOffset = 0f;[Header("是否自动滚动")]public bool isAutoScroll = true; //是否自动滚动[Header("自动滚动时间间隔"), Range(0f, 60f)]public float AutoTime = 1f; //自动滚动时间间隔private void Awake(){scrollRect = GetComponent<ScrollRect>();if (scrollRect == null){Debug.LogError("不存在组件ScrollRect");}else{content = scrollRect.content;if (content == null){Debug.LogError("不存在节点ScrollRect->Content");}else{gridLayoutGroup = content.GetComponent<GridLayoutGroup>();if (gridLayoutGroup == null){Debug.LogError("不存在组件ScrollRect->Content->GridLayoutGroup");}originalCellSize = gridLayoutGroup.cellSize;}}finalPosOffsetBackup = finalPosOffset;}private void Start(){Init();}private void Update(){CheckMove();CheckAutoScroll();if (finalPosOffsetBackup != finalPosOffset){finalPosOffsetBackup = finalPosOffset;Init();ScrollTo(currentIndex);}}private void Init(){pageCount = content.childCount; //子节点数量pagesData = new float[pageCount]; //初始化for (int i = 0; i < pagesData.Length; i++){switch (scrollType){case ScrollType.Horizontal:pagesData[i] = i * (1f / (float) (pageCount - 1)); //给位置的数组赋值break;case ScrollType.Vertical:pagesData[i] = CalculateTopPosition(i);break;}//DELETEMEif (content.GetChild(i).Find("Text") != null)content.GetChild(i).Find("Text").GetComponent<Text>().text = pagesData[i].ToString();}}private float CalculateTopPosition(int childIndex){if (childIndex <= 0) return 0f  +  finalPosOffset;return gridLayoutGroup.padding.top + childIndex * originalCellSize.y + (childIndex - 1) * gridLayoutGroup.spacing.y  +  finalPosOffset;}private void CheckMove(){if (isMoving){timer += Time.unscaledDeltaTime * moveSpeed;switch (scrollType){case ScrollType.Horizontal:scrollRect.horizontalNormalizedPosition = Mathf.Lerp(startMovePos, pagesData[currentIndex], timer);break;case ScrollType.Vertical:content.anchoredPosition = Vector2.Lerp(startMovePosV2, new Vector2(startMovePosV2.x, pagesData[currentIndex]), timer);break;}if (timer > 1){isMoving = false;scrollRect.StopMovement();}}else{scrollRect.StopMovement();}}private void CheckAutoScroll() //自动滑动{if (isDraging){return;}if (isAutoScroll){autotimer += Time.deltaTime;if (autotimer > AutoTime){autotimer = 0;currentIndex++;currentIndex %= pageCount; //取余形成循环ScrollTo(currentIndex);}}}private void ScrollTo(int index){currentIndex = index;timer = 0;isMoving = true;switch (scrollType){case ScrollType.Horizontal:startMovePos = scrollRect.horizontalNormalizedPosition;break;case ScrollType.Vertical:startMovePosV2 = content.anchoredPosition;break;}}public void OnBeginDrag(PointerEventData eventData){isDraging = true;beginDragPointerPos = eventData.position;}public void OnEndDrag(PointerEventData eventData){int minIndex = 0;//计算当最近的一页是哪个switch (scrollType){case ScrollType.Horizontal:for (int i = 0; i < pagesData.Length; i++){if (Mathf.Abs(pagesData[i] - scrollRect.horizontalNormalizedPosition) < Mathf.Abs(pagesData[minIndex] - scrollRect.horizontalNormalizedPosition)){minIndex = i;}}break;case ScrollType.Vertical:var curY = content.anchoredPosition.y;var directionY = Mathf.Sign(eventData.position.y - beginDragPointerPos.y);for (int i = 0; i < pagesData.Length; i++){if (Mathf.Abs(pagesData[i] - curY) - directionY * distanceOffset < Mathf.Abs(pagesData[minIndex] - curY) + directionY * distanceOffset){minIndex = i;}}break;}ScrollTo(minIndex);isDraging = false;autotimer = 0;}
}

备注：Vertical可用，Horizontal未写完，若使用后者请修改相应switch语句。

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