Unity3d—做一个年月日选择器（Scroll Rect拖动效果优化）— 无限滚动 + 锁定元素

效果图

用的是UGUI

我先说思路

通过判断元素的位置信息来改变Hierarchy的顺序 实现无限滚动

改变位置的同时也要不断的调整Content的位置防止乱跳

元素锁定就是直接锁死的元素的移动范围 当只有拖动大于一定程度时才会发生改变

然后是面板设置

整体结构是这样子的

需要注意的是Content需要的两个组件

Content的爸爸只需要一个脚本

大小改变曲线（大致就行）

颜色渐变曲线

最后是脚本

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

 public class DateControl : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler {

     public enum ItemType { _year, _month, _day }

     public ItemType _itemtype;

     RectTransform conentRect;

     RectTransform targetRec;

     Vector3 oldDragPos;

     Vector3 newDragPos;

     public AnimationCurve curve_scale;//改变大小曲线
     public AnimationCurve curve_color;//渐变效果曲线

     List<Text> textList = new List<Text>();

     Button testBtn;

     float
         itemHeight,             //子项item的高
         contentParentHeight,    //Content爸爸的高
         itemNum,                //子项数量
         itemHeight_min,         //子项最小发生改变位置
         itemHeight_max,         //子项最大发生改变位置
         conentLimit,            //Conent纠正位置
         conentSpacing;          //子项间隔大小

     float deltaX, deltaY;

     [HideInInspector]
     public static int _year, _month, _day;

     [HideInInspector]
     int dateItemNum;

     Color itemColor_hig = new Color32(, , , );

     void Awake() {
         conentRect = transform.FindChild("Content").GetComponent<RectTransform>();
         targetRec = transform.parent.FindChild("HighlightTarget").GetComponent<RectTransform>();

     }

     void OnEnable() {
         ItemList();
     }

     void Start() {
         switch (_itemtype) {
             case ItemType._year: InstantiateData(, ); break;
             case ItemType._month: InstantiateData(, ); break;
             case ItemType._day: InstantiateData(, ); break;
         }

         itemNum = transform.FindChild("Content").childCount - ;

         contentParentHeight = conentRect.parent.GetComponent<RectTransform>().sizeDelta.y;

         conentSpacing = conentRect.GetComponent<VerticalLayoutGroup>().spacing / ;

         itemHeight = textList[].rectTransform.sizeDelta.y + conentSpacing;

         if (itemNum %  == ) conentLimit = (itemHeight + ) / ;

         else conentLimit = ;

         conentRect.anchoredPosition = new Vector2(conentRect.anchoredPosition.x, conentLimit);

         deltaX = textList[].GetComponent<RectTransform>().sizeDelta.x;
         deltaY = textList[].GetComponent<RectTransform>().sizeDelta.y;

         Invoke("ItemList", 0.05f);

     }

     /// <summary>
     /// 生成子项item
     /// </summary>
     /// <param name="itemNum">子项数量</param>
     /// <param name="dat">子项最大值</param>
     void InstantiateData(int itemNum, int dat) {
         GameObject go;
         Text testObj = conentRect.FindChild("Text").GetComponent<Text>();
         for (int i = dat - itemNum + ; i <= dat; i++) {
             go = Instantiate(testObj.gameObject, conentRect);
             go.GetComponent<Text>().text = i.ToString();
             go.name = i.ToString();
             textList.Add(go.GetComponent<Text>());
             ShowItem(true);
         }
         Destroy(conentRect.FindChild("Text").gameObject);
     }

     /// <summary>
     /// 是增加或减少
     /// </summary>
     /// <param name="isIncreaseOrdecrease"></param>
     void ShowItem(bool isIncreaseOrdecrease) {
         itemHeight_min = -itemHeight;

         if (_itemtype == ItemType._day) itemHeight_max = -itemHeight * itemNum - ;
         else itemHeight_max = -itemHeight * itemNum;

         if (isIncreaseOrdecrease) {
             foreach (Text rectItem in textList) {
                 if (rectItem.GetComponent<RectTransform>().anchoredPosition.y > itemHeight_min) {
                     print("+");
                     rectItem.transform.SetSiblingIndex((int)itemNum);
                 }
             }
             print(itemHeight_min);
         } else {
             foreach (Text rectItem in textList) {
                 if (rectItem.GetComponent<RectTransform>().anchoredPosition.y < itemHeight_max) {
                     print("-");
                     rectItem.transform.SetSiblingIndex();
                 }
             }
             print(itemHeight_max);

         }
     }

     /// <summary>
     /// 渐变效果，改变大小，高亮显示
     /// </summary>
     void ItemList() {
         foreach (Text item in textList) {
             float indexA = Mathf.Abs(item.GetComponent<RectTransform>().position.y - targetRec.position.y);
             float indexSc_scale = Mathf.Abs(curve_scale.Evaluate(indexA / contentParentHeight));
             float indexSc_color = Mathf.Abs(curve_color.Evaluate(indexA / contentParentHeight));
             if (indexA < ) {
                 item.color = itemColor_hig;
                 switch (_itemtype) {
                     case ItemType._year: _year = int.Parse(item.text); break;
                     case ItemType._month: _month = int.Parse(item.text); break;
                     case ItemType._day: _day = int.Parse(item.text); break;
                 }
             } else item.color = new Color(, , ,  - indexSc_color);

             item.GetComponent<RectTransform>().localScale = new Vector3( - indexSc_scale,  - indexSc_scale * ,  - indexSc_scale);
             //item.GetComponent<RectTransform>().sizeDelta = new Vector2(deltaX - (deltaX * indexSc), deltaY - (deltaY * indexSc));
         }

     }

     /// <summary>
     /// 获取int类型日期，并转换为指定格式
     /// </summary>
     /// <returns></returns>
     public static string GetDateInfo() { return _year + "-" + _month + "-" + _day; }

     /// <summary>
     /// 纠正Conent位置
     /// </summary>
     void UpdateEx() {
         if (conentRect.anchoredPosition.y > conentLimit) {
             ShowItem(true);
             conentRect.anchoredPosition = new Vector2(conentRect.anchoredPosition.x, conentRect.anchoredPosition.y - itemHeight);
         }
         if (conentRect.anchoredPosition.y < conentLimit) {
             ShowItem(false);
             conentRect.anchoredPosition = new Vector2(conentRect.anchoredPosition.x, conentRect.anchoredPosition.y + itemHeight);
         }
     }

     /// <summary>
     /// 获取拖拽信息并改变Conent位置
     /// </summary>
     /// <param name="eventData"></param>
     void SetDraggedPosition(PointerEventData eventData) {
         if (RectTransformUtility.ScreenPointToWorldPointInRectangle(conentRect, eventData.position, eventData.pressEventCamera, out newDragPos)) {
             newDragPos = eventData.position;
             if (Mathf.Abs(newDragPos.y - oldDragPos.y) >= itemHeight) {
                 if (newDragPos.y > oldDragPos.y) {
                     conentRect.anchoredPosition = new Vector2(conentRect.anchoredPosition.x, conentRect.anchoredPosition.y + itemHeight);
                     oldDragPos += new Vector3(, itemHeight, );
                     ItemList();
                 } else {
                     conentRect.anchoredPosition = new Vector2(conentRect.anchoredPosition.x, conentRect.anchoredPosition.y - itemHeight);
                     oldDragPos -= new Vector3(, itemHeight, );
                     ItemList();
                 }
             }
         }
     }

     /// <summary>
     /// 当开始拖拽
     /// </summary>
     /// <param name="eventData"></param>
     public void OnBeginDrag(PointerEventData eventData) {
         oldDragPos = eventData.position;
     }

     public void OnDrag(PointerEventData eventData) {
         SetDraggedPosition(eventData);
         UpdateEx();
     }

     public void OnEndDrag(PointerEventData eventData) {
         SetDraggedPosition(eventData);
         UpdateEx();
     }
 }

照着来的话基本没什么问题

因为赶时间所以很多地方写的简单粗暴请谅解

如果调整元素大小或者间隙大小 需要改变itemHeight_min 和 itemHeight_max 的值

他们分别为

itemHeight_min

itemHeight_max 

也就是元素的最顶层和最底层的Y值

以上就是年月日选择器的具体步骤