使用ScrollRect制作翻页

1.标准的层级结构 ScrollRect->ViewPort->Content，Viewport负责显示区域的大小一般和Mask一起配合使用，Content使用Layout来布局，如果想使用代码来自动定位显示位置需要在Content加上Content size filter.

2.ScrollRectHelper

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

 public class ScrollRectHelper : MonoBehaviour, IBeginDragHandler, IEndDragHandler
 {
     // 滑动速度
     public float smooting = ;

     // 每页显示的项目
     [SerializeField]
     private int countPerPage = ;

     ScrollRect srect;
     // 总页数
     float totalPages;
     // 是否拖拽结束
     bool isDrag = false;
     // 总页数索引比列 0-1
     List<float> listPageValue = new List<float> {  };
     // 滑动的目标位置
     public float targetPos = ;
     // 当前位置索引
     float nowindex = ;                                 

     void Awake()
     {
         srect = GetComponent<ScrollRect>();
     }

     public string PageText()
     {
         return (nowindex + ) + "/" + (totalPages + );
     }

     // 计算每页比例
     public void CalcListPageValue<T>() where T : MonoBehaviour
     {
         T[] items = srect.content.GetComponentsInChildren<T>();
         srect.content.rect.Set(srect.content.rect.width / , srect.content.rect.y, srect.content.rect.width, srect.content.rect.height);
         totalPages = (int)(Math.Ceiling((float)items.Length / countPerPage) - );
         if (items.Length != )
         {
             for (float i = ; i <= totalPages; i++)
             {
                 //Debug.Log(i / totalPages);
                 listPageValue.Add((i / totalPages));
             }
         }
     }

     void Update()
     {
         if (!isDrag)
         {
             srect.horizontalNormalizedPosition = Mathf.Lerp(srect.horizontalNormalizedPosition, targetPos,
                 Time.deltaTime * smooting);
         }

         // Debug
         if (Input.GetKeyDown(KeyCode.LeftArrow)) PressLeft();
         if (Input.GetKeyDown(KeyCode.RightArrow)) PressRight();
     }

     /// <summary>
     /// 拖动开始
     /// </summary>
     /// <param name="eventData"></param>
     public void OnBeginDrag(PointerEventData eventData)
     {
         isDrag = true;
     }

     /// <summary>
     /// 拖拽结束
     /// </summary>
     /// <param name="eventData"></param>
     public void OnEndDrag(PointerEventData eventData)
     {
         isDrag = false;
         var tempPos = srect.horizontalNormalizedPosition; //获取拖动的值
         var index = ;
         float offset = Mathf.Abs(listPageValue[index] - tempPos);    //拖动的绝对值
         for (int i = ; i < listPageValue.Count; i++)
         {
             float temp = Mathf.Abs(tempPos - listPageValue[i]);
             if (temp < offset)
             {
                 index = i;
                 offset = temp;
             }
         }
         targetPos = listPageValue[index];
         nowindex = index;
     }

     public void PressLeft()
     {
         nowindex = Mathf.Clamp(nowindex - , , totalPages);
         targetPos = listPageValue[Convert.ToInt32(nowindex)];
     }

     public void PressRight()
     {
         nowindex = Mathf.Clamp(nowindex + , , totalPages);
         targetPos = listPageValue[Convert.ToInt32(nowindex)];
     }
 }