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      1 /*
      2  * Copyright (C) 2011 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 package com.example.android.supportv13.app;
     17 
     18 import java.util.ArrayList;
     19 
     20 import com.example.android.supportv13.R;
     21 
     22 import android.app.ActionBar;
     23 import android.app.ActionBar.Tab;
     24 import android.app.Activity;
     25 import android.app.Fragment;
     26 import android.app.FragmentTransaction;
     27 import android.content.Context;
     28 import android.os.Bundle;
     29 import android.support.v13.app.FragmentPagerAdapter;
     30 import android.support.v4.view.ViewPager;
     31 
     32 /**
     33  * This demonstrates the use of action bar tabs and how they interact
     34  * with other action bar features.
     35  */
     36 //BEGIN_INCLUDE(complete)
     37 public class ActionBarTabsPager extends Activity {
     38     ViewPager mViewPager;
     39     TabsAdapter mTabsAdapter;
     40 
     41     @Override
     42     protected void onCreate(Bundle savedInstanceState) {
     43         super.onCreate(savedInstanceState);
     44 
     45         mViewPager = new ViewPager(this);
     46         mViewPager.setId(R.id.pager);
     47         setContentView(mViewPager);
     48 
     49         final ActionBar bar = getActionBar();
     50         bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
     51         bar.setDisplayOptions(0, ActionBar.DISPLAY_SHOW_TITLE);
     52 
     53         mTabsAdapter = new TabsAdapter(this, mViewPager);
     54         mTabsAdapter.addTab(bar.newTab().setText("Simple"),
     55                 CountingFragment.class, null);
     56         mTabsAdapter.addTab(bar.newTab().setText("List"),
     57                 FragmentPagerSupport.ArrayListFragment.class, null);
     58         mTabsAdapter.addTab(bar.newTab().setText("Cursor"),
     59                 CursorFragment.class, null);
     60 
     61         if (savedInstanceState != null) {
     62             bar.setSelectedNavigationItem(savedInstanceState.getInt("tab", 0));
     63         }
     64     }
     65 
     66     @Override
     67     protected void onSaveInstanceState(Bundle outState) {
     68         super.onSaveInstanceState(outState);
     69         outState.putInt("tab", getActionBar().getSelectedNavigationIndex());
     70     }
     71 
     72     /**
     73      * This is a helper class that implements the management of tabs and all
     74      * details of connecting a ViewPager with associated TabHost.  It relies on a
     75      * trick.  Normally a tab host has a simple API for supplying a View or
     76      * Intent that each tab will show.  This is not sufficient for switching
     77      * between pages.  So instead we make the content part of the tab host
     78      * 0dp high (it is not shown) and the TabsAdapter supplies its own dummy
     79      * view to show as the tab content.  It listens to changes in tabs, and takes
     80      * care of switch to the correct paged in the ViewPager whenever the selected
     81      * tab changes.
     82      */
     83     public static class TabsAdapter extends FragmentPagerAdapter
     84             implements ActionBar.TabListener, ViewPager.OnPageChangeListener {
     85         private final Context mContext;
     86         private final ActionBar mActionBar;
     87         private final ViewPager mViewPager;
     88         private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();
     89 
     90         static final class TabInfo {
     91             private final Class<?> clss;
     92             private final Bundle args;
     93 
     94             TabInfo(Class<?> _class, Bundle _args) {
     95                 clss = _class;
     96                 args = _args;
     97             }
     98         }
     99 
    100         public TabsAdapter(Activity activity, ViewPager pager) {
    101             super(activity.getFragmentManager());
    102             mContext = activity;
    103             mActionBar = activity.getActionBar();
    104             mViewPager = pager;
    105             mViewPager.setAdapter(this);
    106             mViewPager.setOnPageChangeListener(this);
    107         }
    108 
    109         public void addTab(ActionBar.Tab tab, Class<?> clss, Bundle args) {
    110             TabInfo info = new TabInfo(clss, args);
    111             tab.setTag(info);
    112             tab.setTabListener(this);
    113             mTabs.add(info);
    114             mActionBar.addTab(tab);
    115             notifyDataSetChanged();
    116         }
    117 
    118         @Override
    119         public int getCount() {
    120             return mTabs.size();
    121         }
    122 
    123         @Override
    124         public Fragment getItem(int position) {
    125             TabInfo info = mTabs.get(position);
    126             return Fragment.instantiate(mContext, info.clss.getName(), info.args);
    127         }
    128 
    129         @Override
    130         public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
    131         }
    132 
    133         @Override
    134         public void onPageSelected(int position) {
    135             mActionBar.setSelectedNavigationItem(position);
    136         }
    137 
    138         @Override
    139         public void onPageScrollStateChanged(int state) {
    140         }
    141 
    142         @Override
    143         public void onTabSelected(Tab tab, FragmentTransaction ft) {
    144             Object tag = tab.getTag();
    145             for (int i=0; i<mTabs.size(); i++) {
    146                 if (mTabs.get(i) == tag) {
    147                     mViewPager.setCurrentItem(i);
    148                 }
    149             }
    150         }
    151 
    152         @Override
    153         public void onTabUnselected(Tab tab, FragmentTransaction ft) {
    154         }
    155 
    156         @Override
    157         public void onTabReselected(Tab tab, FragmentTransaction ft) {
    158         }
    159     }
    160 }
    161 //END_INCLUDE(complete)
    162