Android ViewPager又探：增加滑动指示条

  1 package com.example.viewpager.myapplication;
  2 
  3 import android.app.Activity;
  4 import android.graphics.BitmapFactory;
  5 import android.graphics.Matrix;
  6 import android.os.Bundle;
  7 import android.support.v4.view.ViewPager;
  8 import android.util.DisplayMetrics;
  9 import android.view.LayoutInflater;
 10 import android.view.View;
 11 import android.view.animation.Animation;
 12 import android.view.animation.TranslateAnimation;
 13 import android.widget.ImageView;
 14 import android.widget.TextView;
 15 
 16 import java.util.ArrayList;
 17 import java.util.List;
 18 
 19 
 20 public class MainActivity extends Activity {
 21     private View first,second,third;
 22     private ViewPager viewPager;//对应 <android.support.v4.view.ViewPager/>控件
 23     private List<View> viewList;//View数组
 24 
 25     /*滑动条相关定义*/
 26     private ImageView cursor;
 27     private int bmp_width = 0;//游标宽度
 28     private int offset = 0;//游标图片偏移量
 29     private int number = 0;//当前页面编号
 30 
 31     /*Tab页面参数*/
 32     private TextView tv_first;
 33     private TextView tv_second;
 34     private TextView tv_third;
 35 
 36     @Override
 37     protected void onCreate(Bundle savedInstanceState) {
 38         super.onCreate(savedInstanceState);
 39         setContentView(R.layout.activity_main);
 40 
 41         /*TAB页初始化*/
 42         tv_first = (TextView)findViewById(R.id.tv_first);
 43         tv_second = (TextView)findViewById(R.id.tv_second);
 44         tv_third = (TextView)findViewById(R.id.tv_third);
 45 
 46         /*初始化*/
 47         viewPager = (ViewPager)findViewById(R.id.viewpager);
 48         LayoutInflater inflater = getLayoutInflater();
 49         first = inflater.inflate(R.layout.first_page,null);
 50         second = inflater.inflate(R.layout.second_page,null);
 51         third = inflater.inflate(R.layout.third_page,null);
 52 
 53         viewList = new ArrayList<View>();// 将要分页显示的View装入数组中
 54         viewList.add(first);
 55         viewList.add(second);
 56         viewList.add(third);
 57 
 58         //初始化指示器位置
 59         initCursorPos();
 60 
 61         /*适配器部分*/
 62         NewPagerAdapter pagerAdapter = new NewPagerAdapter(viewList);
 63         viewPager.setAdapter(pagerAdapter);
 64 
 65         viewPager.setCurrentItem(0);//设置当前页
 66         viewPager.setOnPageChangeListener(new NewPageChangeListener());//监听页面改变
 67 
 68         /*Tab页面监听*/
 69         tv_first.setOnClickListener(new TabOnClickListener(0));
 70         tv_second.setOnClickListener(new TabOnClickListener(1));
 71         tv_third.setOnClickListener(new TabOnClickListener(2));
 72     }
 73 
 74     //初始化指示器位置
 75     public void initCursorPos() {
 76         // 初始化动画
 77         cursor = (ImageView) findViewById(R.id.cursor);
 78         bmp_width = BitmapFactory.decodeResource(getResources(), R.mipmap.slidebar)
 79                 .getWidth();// 获取图片宽度
 80 
 81         DisplayMetrics dm = new DisplayMetrics();//初始化DisplayMetrics对象
 82         getWindowManager().getDefaultDisplay().getMetrics(dm);//将当前窗口信息放入DisplayMetrics类中
 83         int s_width = dm.widthPixels;// 获取分辨率宽度
 84         offset = (s_width / viewList.size() - bmp_width) / 2;// 计算偏移量(保证滑动条在该tab下正中间)
 85 
 86         Matrix matrix = new Matrix();
 87         matrix.postTranslate(offset, 0);
 88         cursor.setImageMatrix(matrix);// 设置动画初始位置
 89     }
 90 
 91 
 92     //页面改变监听器
 93     public class NewPageChangeListener implements ViewPager.OnPageChangeListener {
 94 
 95         int one = offset * 2 + bmp_width;// 页卡1 -> 页卡2 偏移量
 96         int two = one * 2;// 页卡1 -> 页卡3 偏移量
 97 
 98         @Override
 99         public void onPageSelected(int arg0) {
100             Animation animation = null;
101             switch (arg0) {
102                 case 0:
103                     if (number == 1) {
104                         animation = new TranslateAnimation(one, 0, 0, 0);
105                     } else if (number == 2) {
106                         animation = new TranslateAnimation(two, 0, 0, 0);
107                     }
108                     break;
109                 case 1:
110                     if (number == 0) {
111                         animation = new TranslateAnimation(offset, one, 0, 0);
112                     } else if (number == 2) {
113                         animation = new TranslateAnimation(two, one, 0, 0);
114                     }
115                     break;
116                 case 2:
117                     if (number == 0) {
118                         animation = new TranslateAnimation(offset, two, 0, 0);
119                     } else if (number == 1) {
120                         animation = new TranslateAnimation(one, two, 0, 0);
121                     }
122                     break;
123             }
124             number = arg0;
125             animation.setFillAfter(true);// True:图片停在动画结束位置
126             animation.setDuration(300);
127             cursor.startAnimation(animation);
128         }
129 
130         @Override
131         public void onPageScrolled(int arg0, float arg1, int arg2) {
132         }
133 
134         @Override
135         public void onPageScrollStateChanged(int arg0) {
136         }
137     }
138 
139 
140     /*Tab页面点击监听*/
141     public class TabOnClickListener implements View.OnClickListener{
142         private int num = 0;
143 
144         public TabOnClickListener(int index){
145             num = index;
146         }
147 
148         @Override
149         public void onClick(View v){
150             viewPager.setCurrentItem(num);
151         }
152     }
153 
154 }