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展示效果

原理:

当停止滑动时

判断Contet的horizontalNormalizedPosition

与子Item的缓存值 相减,并得到最小值，然后将Content  horizontalNormalizedPosition滚动过去

使用方式：

直接将脚本挂到ScrollRect上

注意：在创建Content子物体时 或子物体数量变更，需要调用Refresh

代码：

namespace ShangShangQian.Component
{using System.Collections;using System.Collections.Generic;using UnityEngine;using UnityEngine.UI;using UnityEngine.EventSystems;using System.Linq;using UnityEngine.Events;[RequireComponent(typeof(ScrollRect))]public class SnapScrollRect : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler{private RectTransform content;private ScrollRect rect;/// <summary>/// content 的位置应该滚到什么/// </summary>public float target = 1;/// <summary>/// 回滚的速度 0-1 越小越快/// </summary>public float smooting = 0.25f;public float currentVelocity;public float horizontalNormalizedPosition;public List<float> values = new List<float>();public List<float> distances = new List<float>();public List<RectTransform> items = new List<RectTransform>();/// <summary>/// 是否拖拽中/// </summary>public bool isDrag = false;/// <summary>/// 到最近item的距离/// </summary>public float distanceMin;/// <summary>/// 到最近item的索引/// </summary>public int selectIndex;/// <summary>/// 是否匹配滑动中/// </summary>public bool Snaping = false;/// <summary>/// 回滚完毕后调用/// </summary>public UnityEvent<int> OnSnap;void Start(){rect = GetComponent<ScrollRect>();content = rect.content;}/// <summary>/// 刷新数据，content的子物体数量变更时需要调用此函数/// </summary>public void Refresh(){items.Clear();values.Clear();for (int i = 0; i < content.childCount; i++){if (content.GetChild(i).gameObject.activeInHierarchy){items.Add(content.GetChild(i).GetComponent<RectTransform>());}}//累加的变量values.Add(0);//每一个格子的所占比多少  float v = 1f / (items.Count - 1);for (int i = 1; i < items.Count; i++){values.Add(i * v);}//不同子元素数量 item 对应 的content  horizontalNormalizedPosition 数值//1  0  //2  0 1   //3  0 0.5 1//4  0 0.33 0.66 1}void Update(){
#if UNITY_EDITORif (Input.GetKeyDown(KeyCode.A)){Refresh();}
#endif}void FixedUpdate(){horizontalNormalizedPosition = rect.horizontalNormalizedPosition;if (isDrag){return;}if (Snaping){rect.horizontalNormalizedPosition = Mathf.SmoothDamp(rect.horizontalNormalizedPosition, target, ref currentVelocity, smooting);if (Mathf.Abs(rect.horizontalNormalizedPosition - values[selectIndex]) < 0.001f){Snaping = false;Debug.Log("回滚:" + selectIndex);OnSnap.Invoke(selectIndex);}}}public void OnBeginDrag(PointerEventData eventData){isDrag = true;}public void OnDrag(PointerEventData eventData){isDrag = true;}public void OnEndDrag(PointerEventData eventData){isDrag = false;Snaping = true;distances.Clear();//当松手后判断那个距离最近for (int i = 0; i < values.Count; i++){distances.Add(Mathf.Abs(rect.horizontalNormalizedPosition - values[i]));}distanceMin = distances.Min();selectIndex = distances.FindIndex(b => b == distanceMin);target = values[selectIndex];rect.StopMovement();}/// <summary>/// 滚到到指定位置/// </summary>/// <param name="index"></param>public void SnapToIndex(int index){Snaping = true;selectIndex = index;target = values[selectIndex];}}
}