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

public class PageTurning : MonoBehaviour, IPointerClickHandler,IPointerEnterHandler,IPointerExitHandler
{
    public Scrollbar slider;
    //检测鼠标是否在此UI上的布尔值
    public bool Isin;
    // Start is called before the first frame update
    void Start()
    {

    }

    // Update is called once per frame
    void Update()
    {
        ChangePage();
        MouseWheel();
    }

    //让此页面的滚动跟随右侧的滑动条
    void ChangePage()
    {
        if (this.transform.childCount != 0)
        {
            this.GetComponent<VerticalLayoutGroup>().padding.top = Convert.ToInt32(Math.Floor(-slider.value * (this.transform.childCount * this.transform.GetChild(0).GetComponent<RectTransform>().sizeDelta.y - this.GetComponent<RectTransform>().sizeDelta.y)));
            LayoutRebuilder.ForceRebuildLayoutImmediate(this.GetComponent<RectTransform>());
        }
    }

    public void OnPointerClick(PointerEventData pointerEventData)
    {
        
    }

    public void OnPointerEnter(PointerEventData pointerEventData)
    {
        Isin = true;
    }

    public void OnPointerExit(PointerEventData pointerEventData)
    {
        Isin = false;
    }

    void MouseWheel() 
    {
        if (Isin) 
        {
            slider.value += Input.GetAxis("Mouse ScrollWheel")*0.01f;
        }
        if (slider.value > 1) 
        {
            slider.value = 1;
        }
        if (slider.value < 0) 
        {
            slider.value = 0;
        }
    }
}