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      1 /*
      2  * Copyright (C) 2012 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 //BEGIN_INCLUDE(complete)
     33 public class FragmentNestingPagerSupport extends Activity {
     34     ViewPager mViewPager;
     35     TabsAdapter mTabsAdapter;
     36 
     37     @Override
     38     protected void onCreate(Bundle savedInstanceState) {
     39         super.onCreate(savedInstanceState);
     40 
     41         mViewPager = new ViewPager(this);
     42         mViewPager.setId(R.id.pager);
     43         setContentView(mViewPager);
     44 
     45         final ActionBar bar = getActionBar();
     46         bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
     47         bar.setDisplayOptions(0, ActionBar.DISPLAY_SHOW_TITLE);
     48 
     49         mTabsAdapter = new TabsAdapter(this, mViewPager);
     50         mTabsAdapter.addTab(bar.newTab().setText("Simple"),
     51                 CountingFragment.class, null);
     52         mTabsAdapter.addTab(bar.newTab().setText("List"),
     53                 FragmentPagerSupport.ArrayListFragment.class, null);
     54         mTabsAdapter.addTab(bar.newTab().setText("Cursor"),
     55                 CursorFragment.class, null);
     56         mTabsAdapter.addTab(bar.newTab().setText("Tabs"),
     57                 FragmentTabsFragment.class, null);
     58 
     59         if (savedInstanceState != null) {
     60             bar.setSelectedNavigationItem(savedInstanceState.getInt("tab", 0));
     61         }
     62     }
     63 
     64     @Override
     65     protected void onSaveInstanceState(Bundle outState) {
     66         super.onSaveInstanceState(outState);
     67         outState.putInt("tab", getActionBar().getSelectedNavigationIndex());
     68     }
     69 
     70     /**
     71      * This is a helper class that implements the management of tabs and all
     72      * details of connecting a ViewPager with associated TabHost.  It relies on a
     73      * trick.  Normally a tab host has a simple API for supplying a View or
     74      * Intent that each tab will show.  This is not sufficient for switching
     75      * between pages.  So instead we make the content part of the tab host
     76      * 0dp high (it is not shown) and the TabsAdapter supplies its own dummy
     77      * view to show as the tab content.  It listens to changes in tabs, and takes
     78      * care of switch to the correct paged in the ViewPager whenever the selected
     79      * tab changes.
     80      */
     81     public static class TabsAdapter extends FragmentPagerAdapter
     82             implements ActionBar.TabListener, ViewPager.OnPageChangeListener {
     83         private final Context mContext;
     84         private final ActionBar mActionBar;
     85         private final ViewPager mViewPager;
     86         private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();
     87 
     88         static final class TabInfo {
     89             private final Class<?> clss;
     90             private final Bundle args;
     91 
     92             TabInfo(Class<?> _class, Bundle _args) {
     93                 clss = _class;
     94                 args = _args;
     95             }
     96         }
     97 
     98         public TabsAdapter(Activity activity, ViewPager pager) {
     99             super(activity.getFragmentManager());
    100             mContext = activity;
    101             mActionBar = activity.getActionBar();
    102             mViewPager = pager;
    103             mViewPager.setAdapter(this);
    104             mViewPager.setOnPageChangeListener(this);
    105         }
    106 
    107         public void addTab(ActionBar.Tab tab, Class<?> clss, Bundle args) {
    108             TabInfo info = new TabInfo(clss, args);
    109             tab.setTag(info);
    110             tab.setTabListener(this);
    111             mTabs.add(info);
    112             mActionBar.addTab(tab);
    113             notifyDataSetChanged();
    114         }
    115 
    116         @Override
    117         public int getCount() {
    118             return mTabs.size();
    119         }
    120 
    121         @Override
    122         public Fragment getItem(int position) {
    123             TabInfo info = mTabs.get(position);
    124             return Fragment.instantiate(mContext, info.clss.getName(), info.args);
    125         }
    126 
    127         @Override
    128         public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
    129         }
    130 
    131         @Override
    132         public void onPageSelected(int position) {
    133             mActionBar.setSelectedNavigationItem(position);
    134         }
    135 
    136         @Override
    137         public void onPageScrollStateChanged(int state) {
    138         }
    139 
    140         @Override
    141         public void onTabSelected(Tab tab, FragmentTransaction ft) {
    142             Object tag = tab.getTag();
    143             for (int i=0; i<mTabs.size(); i++) {
    144                 if (mTabs.get(i) == tag) {
    145                     mViewPager.setCurrentItem(i);
    146                 }
    147             }
    148         }
    149 
    150         @Override
    151         public void onTabUnselected(Tab tab, FragmentTransaction ft) {
    152         }
    153 
    154         @Override
    155         public void onTabReselected(Tab tab, FragmentTransaction ft) {
    156         }
    157     }
    158 }
    159 //END_INCLUDE(complete)
    160