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(255, 255, 255, 255);

    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(15, 2017); break;
            case ItemType._month: InstantiateData(12, 12); break;
            case ItemType._day: InstantiateData(31, 31); break;
        }

        itemNum = transform.FindChild("Content").childCount - 1;

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

        conentSpacing = conentRect.GetComponent<VerticalLayoutGroup>().spacing / 2;

        itemHeight = textList[0].rectTransform.sizeDelta.y + conentSpacing;

        if (itemNum % 2 == 0) conentLimit = (itemHeight + 5) / 2;

        else conentLimit = 0;

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

        deltaX = textList[0].GetComponent<RectTransform>().sizeDelta.x;
        deltaY = textList[0].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 + 1; 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 - 95;
        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(0);
                }
            }
            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 < 15) {
                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(0, 0, 0, 1 - indexSc_color);

            item.GetComponent<RectTransform>().localScale = new Vector3(1 - indexSc_scale, 1 - indexSc_scale * 3, 1 - 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(0, itemHeight, 0);
                    ItemList();
                } else {
                    conentRect.anchoredPosition = new Vector2(conentRect.anchoredPosition.x, conentRect.anchoredPosition.y - itemHeight);
                    oldDragPos -= new Vector3(0, itemHeight, 0);
                    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