[notes] unity Scrollview button page turning

Illustration above ： Generate buttons through code , One page 6 Button , Switch left and right to turn pages .

Illustration above ： add to GridLayoutGroup Components can automatically arrange elements （ In addition, there are parallel and vertical sorting components HorizontalLayoutGroup ,VerticalLayoutGroup）, You can adjust the arrangement spacing by adjusting the attributes . Upper figure 400 Is the width of one page ,200 Is the page width occupied by a single column element , Because my case is 2 Column buttons , Therefore, the multiple of the width of the single column element must be equal to the width of one page , Otherwise, there will be a similar phenomenon of insufficient or excessive page turning .

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

public class TestScroolView : MonoBehaviour {

    public GameObject objBtn;

    private RectTransform contents;
    private ScrollRect scrollrect;

   // Set according to the demand 
    private int btnAllcount = 12;// Total number of buttons 
    private int btnCount = 6;// Number of buttons per page 

    private float contentsWidth;
    private float delta_X;
    private float targePoint;
    private bool isRoll; // Turn page 

    void Start()
    {
        contents = transform.Find("Viewport/Content") as RectTransform;
        scrollrect = transform.GetComponent<ScrollRect>();

        contentsWidth = contents.sizeDelta.x;
        // To obtain by calculation contents The length of 
        delta_X = Mathf.CeilToInt(btnAllcount / btnCount) * contentsWidth;
        // to contents Set the size 
        contents.sizeDelta = new Vector2(delta_X, contents.sizeDelta.y);
        // to contents Add a button 
        for (int i = 0; i < btnAllcount; i++)
        {
            GameObject obj = Instantiate(objBtn, contents);
            //obj.transform.GetChild(0).GetComponent<Text>().text = i.ToString();
        }
    }

    private void OnGUI()
    {
        // Left button 
        if (GUI.Button(new Rect(200, 80, 100, 30), " The previous page "))
        {
            isRoll = true;
            targePoint -= 1 / (delta_X / contentsWidth - 1);
            if (targePoint < 0)
                targePoint = 0;

        }
        // Right button 
        if (GUI.Button(new Rect(420, 80, 100, 30), " The next page "))
        {
            isRoll = true;
            targePoint += 1 / (delta_X / contentsWidth - 1);
            if (targePoint > 1)
                targePoint = 1;

        }

        // Page turning 
        if (isRoll)
        {
            print(" Page turning ");
            if (Mathf.Abs(scrollrect.horizontalNormalizedPosition - targePoint) < 0.01f)
            {
                scrollrect.horizontalNormalizedPosition = targePoint;
                isRoll = false;
                return;
            }
            // Set the horizontal scroll position 
            scrollrect.horizontalNormalizedPosition = Mathf.Lerp(scrollrect.horizontalNormalizedPosition, targePoint, Time.timeScale * 0.1f);
        }
    }
}