Unity中的ScrollRect滑动结束后，自动将最靠近中间的元素居中

TheLudGamer · 发表于 2022-4-27 14:22

思路

在停止滑动（OnEndDrag）时，调整Content的localPosX：使其逐渐变为与其最接近的若干的标准PosX中的那个。
说明

当前只支持横向滑动。

2种模式：

用法

将UIScrollRectAdjustor挂在ScrollRect同级节点上。

可配置

具体实现

UIScrollRectAdjustor.cs
using System.Collections;using System.Collections.Generic;using UnityEngine;using UnityEngine.UI;using UnityEngine.EventSystems;[RequireComponent(typeof(ScrollRect))]public class UIScrollRectAdjustor : MonoBehaviour, IEndDragHandler, IBeginDragHandler{ private ScrollRect _scrollRect; private RectTransform _contentRectTrans; private float _minX; private float _baseX; private float _xOffset; [SerializeField,Header("自动移动时的移动速度")] private float _moveSpeed = 3000; private IEnumerator _autoMoveCoroutine; [SerializeField, Header("方向优先")] private bool _shouldBaseOnMoveDir; private void Start() { Init(); } private void OnDestroy() { Destroy(); } public void Init() { _minX = 0; _scrollRect = GetComponent<ScrollRect>(); _contentRectTrans = _scrollRect.content; var gridLayoutGroup = _contentRectTrans.GetComponent<GridLayoutGroup>(); _baseX = gridLayoutGroup.cellSize.x / 2 + gridLayoutGroup.padding.left; _xOffset = gridLayoutGroup.cellSize.x + gridLayoutGroup.spacing.x; } public void Destroy() { StopAutoMove(); _scrollRect = null; _contentRectTrans = null; } public void OnBeginDrag(PointerEventData eventData) { if (_minX == 0) { var gridLayoutGroup = _contentRectTrans.GetComponent<GridLayoutGroup>(); _minX = _contentRectTrans.sizeDelta.x - gridLayoutGroup.padding.right - gridLayoutGroup.cellSize.x - gridLayoutGroup.spacing.x / 2; _minX *= -1; } StopAutoMove(); } private bool _isLeftMove; public void OnEndDrag(PointerEventData eventData) { float curX = _contentRectTrans.localPosition.x; if (curX < 0) { _isLeftMove = _scrollRect.velocity.x < 0; float suitableX = GetSuitableX(curX); StartAutoMove(curX, suitableX); } } private float GetSuitableX(float curX) { float suitableX = curX; int index = 0; float leftX; float rightX; while (suitableX >= _minX) { leftX = GetX(index); rightX = GetX(index + 1); if (leftX >= curX && rightX <= curX) { var leftXOffset = Mathf.Abs(leftX - curX); var rightXOffset = Mathf.Abs(rightX - curX); if (_shouldBaseOnMoveDir) { suitableX = _isLeftMove ? rightX : leftX; } else { suitableX = leftXOffset < rightXOffset ? leftX : rightX; } break; } index++; } return Mathf.Max(suitableX, _minX); float GetX(int i) { float value = 0; if (i > 0) { value = (_baseX + _xOffset * i) * -1 + _baseX; } return value; } } private void StartAutoMove(float beginX, float endX) { StopAutoMove(); _autoMoveCoroutine = AutoMoveCoroutine(beginX, endX); StartCoroutine(_autoMoveCoroutine); } private void StopAutoMove() { if (_autoMoveCoroutine != null) { StopCoroutine(_autoMoveCoroutine); _autoMoveCoroutine = null; } } private IEnumerator AutoMoveCoroutine(float beginX, float endX) { float timer = 0f; float moveTime = Mathf.Abs(beginX - endX) / _moveSpeed; while (timer < moveTime) { _contentRectTrans.localPosition = new Vector3(Mathf.Lerp(beginX, endX, timer / moveTime), _contentRectTrans.localPosition.y, _contentRectTrans.localPosition.z); timer += Time.deltaTime; yield return null; } _contentRectTrans.localPosition = new Vector3(endX, _contentRectTrans.localPosition.y, _contentRectTrans.localPosition.z); _scrollRect.StopMovement(); }}

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