【UGUI】UGUI 滑动翻页【旧】

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

public class ScrollPage : MonoBehaviour, IBeginDragHandler, IEndDragHandler
{
	ScrollRect rect;
	//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 };
	List pages = new List ();
	//	int currentPageIndex = -1;
	public GameObject[] ui_Point;
	//滑动速度
	public float smooting = 8;

	//滑动的起始坐标
	float targethorizontal = 0;

	//是否拖拽结束
	bool isDrag = false;

	/// 

	/// 用于返回一个页码，-1说明page的数据为0
	/// 

	float startime = 0f;
	float delay = 0.1f;

	void Awake ()
	{
//		OnPageChanged (3, 0);
	}

	// Use this for initialization
	void Start ()
	{
		rect = transform.GetComponent ();
		//rect.horizontalNormalizedPosition = 0;
		//UpdatePages();      
		startime = Time.time;
//		GameUtility.SetActive (ui_Point, 0);	
	}

	void Update ()
	{
		if (Time.time < startime + delay)
			return;
		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 (!isDrag && pages.Count > 0) {
			rect.horizontalNormalizedPosition = Mathf.Lerp (rect.horizontalNormalizedPosition, targethorizontal, Time.deltaTime * smooting);
		}
		if (rect.horizontalNormalizedPosition > 1) {
			rect.horizontalNormalizedPosition = 1;
		} else if (rect.horizontalNormalizedPosition < 0) {
			rect.horizontalNormalizedPosition = 0;
		}
	}

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

	public void OnEndDrag (PointerEventData eventData)
	{
		isDrag = false;

		float posX = rect.horizontalNormalizedPosition;
		int index = 0;
		//假设离第一位最近
		float offset = Mathf.Abs (pages [index] - posX);
		for (int i = 1; i < pages.Count; i++) {
			float temp = Mathf.Abs (pages [i] - posX);
			if (temp < offset) {
				index = i;

				//保存当前的偏移量
				//如果到最后一页。反翻页。所以要保存该值，如果不保存。你试试效果就知道
				offset = temp;
			}
		}


		/*
         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];

		targethorizontal = pages [index];

	}

	void UpdatePages ()
	{
		// 获取子对象的数量
		int count = this.rect.content.childCount;
		int temp = 0;
		for (int i = 0; i < count; i++) {
			if (this.rect.content.GetChild (i).gameObject.activeSelf) {
				temp++;
			}
		}
		count = temp;
        
		if (pages.Count != count) {
			if (count != 0) {
				pages.Clear ();
				for (int i = 0; i < count; i++) {
					float page = 0;
					if (count != 1)
						page = i / ((float)(count - 1));
					pages.Add (page);
//					Debug.Log(i.ToString() + " page:" + page.ToString());
				}
			}
			OnEndDrag (null);
		}
	}
}