/// Credit Mrs. YakaYocha 
/// Sourced from - https://www.youtube.com/channel/UCHp8LZ_0-iCvl-5pjHATsgw
/// Please donate: https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=RJ8D9FRFQF9VS
 
using UnityEngine.Events;
 
namespace UnityEngine.UI.Extensions
{
 [RequireComponent(typeof(ScrollRect))]
 [AddComponentMenu("Layout/Extensions/Vertical Scroller")]
 public class UIVerticalScroller : MonoBehaviour
 {
  [Tooltip("Scrollable area (content of desired ScrollRect)")]
  public RectTransform _scrollingPanel;
  [Tooltip("Elements to populate inside the scroller")]
  public GameObject[] _arrayOfElements;
  [Tooltip("Center display area (position of zoomed content)")]
  public RectTransform _center;
  [Tooltip("Select the item to be in center on start. (optional)")]
  public int StartingIndex = -1;
  [Tooltip("Button to go to the next page. (optional)")]
  public GameObject ScrollUpButton;
  [Tooltip("Button to go to the previous page. (optional)")]
  public GameObject ScrollDownButton;
  [Tooltip("Event fired when a specific item is clicked, exposes index number of item. (optional)")]
  public UnityEvent ButtonClicked;
 
 
  private float[] distReposition;
  private float[] distance;
  //private int elementsDistance;
  private int minElementsNum;
  private int elementLength;
  //private int elementHalfLength;
  private float deltaY;
  private string result;
 
  public UIVerticalScroller() { }
 
  public UIVerticalScroller(RectTransform scrollingPanel, GameObject[] arrayOfElements, RectTransform center)
  {
   _scrollingPanel = scrollingPanel;
   _arrayOfElements = arrayOfElements;
   _center = center;
  }
 
 
  public void Awake()
  {
   var scrollRect = GetComponent();
   if (!_scrollingPanel)
   {
    _scrollingPanel = scrollRect.content;
   }
   if (!_center)
   {
    Debug.LogError("Please define the RectTransform for the Center viewport of the scrollable area");
   }
   if (_arrayOfElements == null || _arrayOfElements.Length == 0)
   {
    var childCount = scrollRect.content.childCount;
    if (childCount > 0)
    {
     _arrayOfElements = new GameObject[childCount];
     for (int i = 0; i < childCount; i++)
     {
      _arrayOfElements[i] = scrollRect.content.GetChild(i).gameObject;
     }     
    }
   }
  }
 
  public void Start()
  {
   if (_arrayOfElements.Length < 1)
   {
    Debug.Log("No child content found, exiting..");
    return;
   }
 
   elementLength = _arrayOfElements.Length;
   distance = new float[elementLength];
   distReposition = new float[elementLength];
 
   //get distance between buttons
   //elementsDistance = (int)Mathf.Abs(_arrayOfElements[1].GetComponent().anchoredPosition.y - _arrayOfElements[0].GetComponent().anchoredPosition.y);
   deltaY = _arrayOfElements[0].GetComponent().rect.height * elementLength / 3 * 2;
   Vector2 startPosition = new Vector2(_scrollingPanel.anchoredPosition.x, -deltaY);
   _scrollingPanel.anchoredPosition = startPosition;
 
   for (var i = 0; i < _arrayOfElements.Length; i++)
   {
    AddListener(_arrayOfElements[i], i);
   }
 
   if (ScrollUpButton)
    ScrollUpButton.GetComponent().onClick.AddListener(() => { ScrollUp(); });
 
   if (ScrollDownButton)
    ScrollDownButton.GetComponent().onClick.AddListener(() => { ScrollDown(); });
 
   if (StartingIndex > -1)
   {
    StartingIndex = StartingIndex > _arrayOfElements.Length ? _arrayOfElements.Length - 1 : StartingIndex;
    SnapToElement(StartingIndex);
   }
  }
 
  private void AddListener(GameObject button, int index)
  {
   button.GetComponent().onClick.AddListener(() => DoSomething(index));
  }
 
  private void DoSomething(int index)
  {
   if (ButtonClicked != null)
   {
    ButtonClicked.Invoke(index);
   }
  }
 
  public void Update()
  {
   if (_arrayOfElements.Length < 1)
   {
    return;
   }
 
   for (var i = 0; i < elementLength; i++)
   {
    distReposition[i] = _center.GetComponent().position.y - _arrayOfElements[i].GetComponent().position.y;
    distance[i] = Mathf.Abs(distReposition[i]);
 
    //Magnifying effect
    float scale = Mathf.Max(0.7f, 1 / (1 + distance[i] / 200));
    _arrayOfElements[i].GetComponent().transform.localScale = new Vector3(scale, scale, 1f);
   }
   float minDistance = Mathf.Min(distance);
 
   for (var i = 0; i < elementLength; i++)
   {
    _arrayOfElements[i].GetComponent().interactable = false;
    if (minDistance == distance[i])
    {
     minElementsNum = i;
     _arrayOfElements[i].GetComponent().interactable = true;
     result = _arrayOfElements[i].GetComponentInChildren().text;
    }
   }
 
   ScrollingElements(-_arrayOfElements[minElementsNum].GetComponent().anchoredPosition.y);
  }
 
  private void ScrollingElements(float position)
  {
   float newY = Mathf.Lerp(_scrollingPanel.anchoredPosition.y, position, Time.deltaTime * 1f);
   Vector2 newPosition = new Vector2(_scrollingPanel.anchoredPosition.x, newY);
   _scrollingPanel.anchoredPosition = newPosition;
  }
 
  public string GetResults()
  {
   return result;
  }
 
  public void SnapToElement(int element)
  {
   float deltaElementPositionY = _arrayOfElements[0].GetComponent().rect.height * element;
   Vector2 newPosition = new Vector2(_scrollingPanel.anchoredPosition.x, -deltaElementPositionY);
   _scrollingPanel.anchoredPosition = newPosition;
 
  }
 
  public void ScrollUp()
  {
   float deltaUp = _arrayOfElements[0].GetComponent().rect.height / 1.2f;
   Vector2 newPositionUp = new Vector2(_scrollingPanel.anchoredPosition.x, _scrollingPanel.anchoredPosition.y - deltaUp);
   _scrollingPanel.anchoredPosition = Vector2.Lerp(_scrollingPanel.anchoredPosition, newPositionUp, 1);
  }
 
  public void ScrollDown()
  {
   float deltaDown = _arrayOfElements[0].GetComponent().rect.height / 1.2f;
   Vector2 newPositionDown = new Vector2(_scrollingPanel.anchoredPosition.x, _scrollingPanel.anchoredPosition.y + deltaDown);
   _scrollingPanel.anchoredPosition = newPositionDown;
  }
 }
}

/// Credit Mrs. YakaYocha 
/// Sourced from - https://www.youtube.com/channel/UCHp8LZ_0-iCvl-5pjHATsgw
/// Please donate: https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=RJ8D9FRFQF9VS
 
using UnityEngine.Events;
 
namespace UnityEngine.UI.Extensions
{
 [RequireComponent(typeof(ScrollRect))]
 [AddComponentMenu("Layout/Extensions/Vertical Scroller")]
 public class UIVerticalScrollerMove : MonoBehaviour
 {
  [Tooltip("Scrollable area (content of desired ScrollRect)")]
  public RectTransform _scrollingPanel;//展示面板
  [Tooltip("Elements to populate inside the scroller")]
  public GameObject[] _arrayOfElements;//长度元素
  [Tooltip("Center display area (position of zoomed content)")]
  public RectTransform _center;//位置
  [Tooltip("Select the item to be in center on start. (optional)")]
  public int StartingIndex = -1;//初始指针（外界提供）
  [Tooltip("Button to go to the next page. (optional)")]
  public GameObject ScrollLeftButton;//左按钮
  [Tooltip("Button to go to the previous page. (optional)")]
  public GameObject ScrollRightButton;//右按钮
  [Tooltip("Event fired when a specific item is clicked, exposes index number of item. (optional)")]
  public UnityEvent ButtonClicked;//按钮点击
 
 
  private float[] distReposition;//长度改变
  private float[] distance;//长度列表
  //private int elementsDistance;
  private int minElementsNum;//最小元素数
  private int elementLength;//元素长度
  //private int elementHalfLength;
  private float deltaX;//移动x
  private string result;//结果
 
  public UIVerticalScrollerMove() { }//构造函数
 
  public UIVerticalScrollerMove(RectTransform scrollingPanel, GameObject[] arrayOfElements, RectTransform center)
  {
   _scrollingPanel = scrollingPanel;
   _arrayOfElements = arrayOfElements;
   _center = center;
  }
 
 
  //初始化启动
  public void Awake()
  {
   var scrollRect = GetComponent();//获取到排列
   if (!_scrollingPanel)
   {
    _scrollingPanel = scrollRect.content;//如果不是展示面板，获取该物体的可滚动的面板
   }
   if (!_center)//如果设置不成功，打印失败
   {
    Debug.LogError("Please define the RectTransform for the Center viewport of the scrollable area");
   }
   if (_arrayOfElements == null || _arrayOfElements.Length == 0)
   {
    var childCount = scrollRect.content.childCount;
    if (childCount > 0)
    {
     _arrayOfElements = new GameObject[childCount];
     for (int i = 0; i < childCount; i++)
     {
      _arrayOfElements[i] = scrollRect.content.GetChild(i).gameObject;
     }     
    }
   }//获取子物体的长度
  }
 
  //初始化启动
  public void Start()
  {
   if (_arrayOfElements.Length < 1)
   {
    Debug.Log("No child content found, exiting..");
    return;
   }//没有子物体的时候，打印寻找失败
 
   elementLength = _arrayOfElements.Length;
   distance = new float[elementLength];
   distReposition = new float[elementLength];//通过子物体的长度定义距离长度列表与移动长度列表
 
   //get distance between buttons
   //elementsDistance = (int)Mathf.Abs(_arrayOfElements[1].GetComponent().anchoredPosition.y - _arrayOfElements[0].GetComponent().anchoredPosition.y);
   deltaX = _arrayOfElements[0].GetComponent().rect.width * elementLength / 3 * 2;
   Vector2 startPosition = new Vector2( -deltaX,_scrollingPanel.anchoredPosition.y);
   _scrollingPanel.anchoredPosition = startPosition;//获取到更改的按钮
 
   for (var i = 0; i < _arrayOfElements.Length; i++)
   {
    AddListener(_arrayOfElements[i], i);
   }//监听每个按钮上挂载的方法
 
   //如果左右按钮的话，分别监听不同的方法
   if (ScrollLeftButton)
    ScrollLeftButton.GetComponent().onClick.AddListener(() => { ScrollLeft(); });
 
   if (ScrollRightButton)
    ScrollRightButton.GetComponent().onClick.AddListener(() => { ScrollRight(); });
   
   //比较外界提供的初始指针并进行初始定位
   if (StartingIndex > -1)
   {
    StartingIndex = StartingIndex > _arrayOfElements.Length ? _arrayOfElements.Length - 1 : StartingIndex;
    SnapToElement(StartingIndex);
   }
  }
 
  //让该物体监听到自己所对应的事件
  private void AddListener(GameObject button, int index)
  {
   button.GetComponent().onClick.AddListener(() => DoSomething(index));
  }
 
  //index按钮对应的点击状态
  private void DoSomething(int index)
  {
   if (ButtonClicked != null)
   {
    ButtonClicked.Invoke(index);
   }
  }
 
  //逻辑更新
  public void Update()
  {
   if (_arrayOfElements.Length < 1)
   {
    return;
   }//子物体为空的时候返回
 
   for (var i = 0; i < elementLength; i++)
   {
    distReposition[i] = _center.GetComponent().position.x - _arrayOfElements[i].GetComponent().position.x;
    distance[i] = Mathf.Abs(distReposition[i]);
 
    //Magnifying effect
    float scale = Mathf.Max(0.7f, 1 / (1 + distance[i] / 200));
    _arrayOfElements[i].GetComponent().transform.localScale = new Vector3(scale, scale, 1f);
   }//不断更新可滑动面板下面的物体下面的动态数列
   float minDistance = Mathf.Min(distance);//求出最小间距
 
   for (var i = 0; i < elementLength; i++)
   {
    _arrayOfElements[i].GetComponent().interactable = false;
    if (minDistance == distance[i])
    {
     minElementsNum = i;
     _arrayOfElements[i].GetComponent().interactable = true;
     result = _arrayOfElements[i].GetComponentInChildren().text;
    }
   }//除了被选中的物体，其余物体都是不可交互的
 
   ScrollingElements(-_arrayOfElements[minElementsNum].GetComponent().anchoredPosition.x);//不断向着新坐标移动
  }
 
  //不断移动坐标，保证向着目标点移动
  private void ScrollingElements(float position)
  {
   float newX= Mathf.Lerp(_scrollingPanel.anchoredPosition.x, position, Time.deltaTime * 1f);
   Vector2 newPosition = new Vector2(newX,_scrollingPanel.anchoredPosition.y);
   _scrollingPanel.anchoredPosition = newPosition;
  }
 
  public string GetResults()
  {
   return result;
  }
 
  //通过指针计算该物体在坐标栏下的位置
  public void SnapToElement(int element)
  {
   float deltaElementPositionX = _arrayOfElements[0].GetComponent().rect.width * element;
   Vector2 newPosition = new Vector2(-deltaElementPositionX,_scrollingPanel.anchoredPosition.y);
   _scrollingPanel.anchoredPosition = newPosition;
  }
 
  //左右滑动
  public void ScrollLeft()
  {
   float deltaLeft = _arrayOfElements[0].GetComponent().rect.width / 1.2f;
   Vector2 newPositionLeft = new Vector2(_scrollingPanel.anchoredPosition.x-deltaLeft, _scrollingPanel.anchoredPosition.y);
   _scrollingPanel.anchoredPosition = Vector2.Lerp(_scrollingPanel.anchoredPosition,newPositionLeft, 1);
  }
 
  public void ScrollRight()
  {
   float deltaRight = _arrayOfElements[0].GetComponent().rect.width / 1.2f;
   Vector2 newPositionRight = new Vector2(_scrollingPanel.anchoredPosition.x+deltaRight, _scrollingPanel.anchoredPosition.y);
   _scrollingPanel.anchoredPosition = newPositionRight;
  }
 }
}

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.UI.Extensions;
 
public class ScrollingCalendarTest : MonoBehaviour {
 public RectTransform monthsScrollingPanel;
 public GameObject monthsButtonPrefab;
 private GameObject[] monthsButtons;
 public RectTransform monthCenter;
 
 private int monthsSet;
 
 UIVerticalScrollerMove monthsVerticalScroller;
 //Initialize Months
 //生成预制体
 private void InitializeMonths()
 {
 int[] months = new int[12];
 
 monthsButtons = new GameObject[months.Length];
 for (int i = 0; i < months.Length; i++)
 {
 string month = "";
 months[i] = i;
 
 GameObject clone = (GameObject)Instantiate(monthsButtonPrefab, new Vector3(i * 380,0, 0), Quaternion.Euler(new Vector3(0, 0, 0))) as GameObject;
 clone.transform.SetParent(monthsScrollingPanel, false);
 clone.transform.localScale = new Vector3(1, 1, 1);
 
 month = ""+i;
 
 clone.GetComponentInChildren().text = month;
 clone.name = "Month_" + months[i];
 clone.AddComponent();
 monthsButtons[i] = clone;
 }
 }
 // Use this for initialization
  public void Awake()
  {
   InitializeMonths();
 
   //Yes Unity complains about this but it doesn't matter in this case.
   monthsVerticalScroller = new UIVerticalScrollerMove(monthsScrollingPanel, monthsButtons, monthCenter);
 
   monthsVerticalScroller.Start();
  }
 
  public void SetDate()
  {
//   monthsSet = int.Parse(inputFieldMonths.text) - 1;
 
   monthsVerticalScroller.SnapToElement(monthsSet);
  }
 
  void Update()
  {
   monthsVerticalScroller.Update();
 
   string monthString = monthsVerticalScroller.GetResults();
 
  }
 
 
  public void MonthsScrollUp()
  {
   monthsVerticalScroller.ScrollLeft();
  }
 
  public void MonthsScrollDown()
  {
   monthsVerticalScroller.ScrollRight();
  }
 
}