GHZWXWebGL/Assets/Source/UI/ScrollPage.cs

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

public class ScrollPage : MonoBehaviour, IBeginDragHandler, IEndDragHandler
{
    //滑动速度
    public float smooting = 10;
    public float duration =  0.5f;
    public float minMoveOffset = 0.05f;
    private ScrollRect mRect;
    //页面：0，1，2，3  索引从0开始
    //每页占的比列：0/3=0  1/3=0.333  2/3=0.6666 3/3=1
    //float[] pages = { 0f, 0.333f, 0.6666f, 1f };
    private List<float> mPages = new List<float>();
    private int mCurrentPageIndex = 0;
    //滑动的起始坐标
    private float mTargethorizontal = 0;
    //是否拖拽结束
    private bool mIsDrag = false;
    private bool mIsStart = false;
    //最小缩放
    public  float maxScale = 1.5f;
   public  Transform content;
    public new Camera camera;

    /// <summary>
    /// 用于返回一个页码，-1说明page的数据为0
    /// </summary>
    public SystemDelegate.IntDelegate OnPageChanged;

    public SystemDelegate.IntDelegate OnPageStart;

    // Use this for initialization
    void Start()
    {
        mRect = transform.GetComponent<ScrollRect>();
        camera = GameObject.Find("UICamera").GetComponent<Camera>();
     
        //mRect.horizontalNormalizedPosition = 0;
        //UpdatePages();
        StartCoroutine(DelayStart() );    
    }

    IEnumerator DelayStart(){
        yield return 1;
        yield return 1;
        mIsStart = true;
        UpdatePages();
        if (mCurrentPageIndex != 0){
            mTargethorizontal = mPages[mCurrentPageIndex];
            //OnEndDrag(null);
        }
        if (OnPageStart!=null ){
            OnPageStart(mCurrentPageIndex );
        }

    }

    public void SetPageIndex(int pageIndex ){
        //Debug.Log("page index is " + pageIndex );
        mCurrentPageIndex = pageIndex;
        


        if (!mIsStart){
            return;
        }
        mCurrentPageIndex = Mathf.Min(mPages.Count-1, mCurrentPageIndex);
        mCurrentPageIndex = Mathf.Max(0, mCurrentPageIndex);
        
        if (OnPageChanged != null ){
            OnPageChanged(mCurrentPageIndex);
        }
        mTargethorizontal = mPages[mCurrentPageIndex];
        
    }
    
    void Update()
    {
        UpdateItemScale();
        if (mIsStart ){
            UpdatePages();
        }
        //如果不判断。当在拖拽的时候要也会执行插值，所以会出现闪烁的效果
        //这里只要在拖动结束的时候。在进行插值
        if (!mIsDrag && mPages.Count>0)
        {
            mRect.horizontalNormalizedPosition = 
                Mathf.Lerp(mRect.horizontalNormalizedPosition, mTargethorizontal, Time.deltaTime * smooting);
        }
    }
    public void UpdateItemScale()
    {
        List<GameObject> lis = new List<GameObject>();
        for (int i = 0; i < content.transform.childCount; i++)
        {
            lis.Add(content.transform.GetChild(i).gameObject);

        }
        foreach (var item in lis)
        {
            Vector2 pos = RectTransformUtility.WorldToScreenPoint(camera, item.transform.position);
            Vector2 dir = (pos - new Vector2(Screen.width / 2, pos.y)) / Screen.height;

            float cos;

            if (pos.x > Screen.width / 2)
            {


                cos = -dir.x;
                //缩放       

            }
            else
            {

                cos = dir.x;

            }
            float scale = (float) Math.Round( cos + 1.6f,1);
          
            scale = Mathf.Clamp(scale, 1,maxScale);
            item.transform.localScale = new Vector3(scale, scale, scale);


        }
    }




    public int GetPageCount(){
        return mPages.Count;
    }

    public void OnBeginDrag(PointerEventData eventData)
    {
        mIsDrag = true;
    }

    public int GetSelectIndex(){
        return mCurrentPageIndex;
    }

    public void OnEndDrag(PointerEventData eventData)
    {
       
        mIsDrag = false;
        float posX = mRect.horizontalNormalizedPosition;        
        float offset = mPages[mCurrentPageIndex] - posX;
        // Debug.Log("offset is " + offset );
        int lastIndex = mCurrentPageIndex;
        if (Mathf.Abs(offset ) > minMoveOffset ){
            if (offset < 0){
                mCurrentPageIndex++;
            }else{
                mCurrentPageIndex--;
            }
           
            Debug.Log("switch to " + mCurrentPageIndex );
            mCurrentPageIndex = Mathf.Min(mPages.Count-1, mCurrentPageIndex);
            mCurrentPageIndex = Mathf.Max(0, mCurrentPageIndex);
            if (lastIndex!=mCurrentPageIndex ){
                // Debug.Log("switch to " + mCurrentPageIndex );
                if (OnPageChanged != null ){
                    OnPageChanged(mCurrentPageIndex);
                }
                mTargethorizontal = mPages[mCurrentPageIndex];
                Debug.LogWarning( "index "+ mCurrentPageIndex+ " value "+  mTargethorizontal);
            }
            
        }

        /*
         因为这样效果不好。没有滑动效果。比较死板。所以改为插值
         */
        //rect.horizontalNormalizedPosition = page[index];


    }

    void UpdatePages()
    {
        mRect = transform.GetComponent<ScrollRect>();
        // 获取子对象的数量
        int count = this.mRect.content.childCount;
        int temp = 0;
        for(int i=0; i<count; i++)
        {
            if(this.mRect.content.GetChild(i).gameObject.activeSelf)
            {
                temp++;
            }
        }
        count = temp;
        
        if (mPages.Count!=count)
        {
            if (count != 0)
            {
                float unitX = mRect.content.GetComponent<RectTransform>().sizeDelta.x/ (float)count;
                float unitCount = mRect.viewport.GetComponent<RectTransform>().sizeDelta.x/unitX;
                if(unitCount<1)
                {
                    unitCount = 1;
                }
                mPages.Clear();
                for (int i = 0; i < count; i++)
                {
                    float page = 0;
                    if(count>unitCount)
                        page = i / ((float)(count-unitCount));
                    page = page < 1 ? page : 1;
                    mPages.Add(page);
                    //Debug.LogWarning(i.ToString() + " page:" + page.ToString());
                }
            }
            //OnEndDrag(null);
        }
    }

    public GameObject GetItem(int index)
    {
        mRect = transform.GetComponent<ScrollRect>();
        return mRect.content.GetChild(index).gameObject;
    }
}