1 /*
2  * Copyright 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 
17 package com.example.android.tabcompat.lib;
18 
19 import android.app.ActionBar;
20 import android.os.Bundle;
21 import android.support.v4.app.Fragment;
22 import android.support.v4.app.FragmentActivity;
23 import android.support.v4.app.FragmentTransaction;
24 
25 /**
26  * Helper class to build tabs on Honeycomb. Call {@link TabCompatActivity#getTabHelper()}
27  * to get the generic instance for compatibility with older versions.
28  */
29 public class TabHelperHoneycomb extends TabHelper {
30 
31     ActionBar mActionBar;
32 
TabHelperHoneycomb(FragmentActivity activity)33     protected TabHelperHoneycomb(FragmentActivity activity) {
34         super(activity);
35     }
36 
37     @Override
setUp()38     protected void setUp() {
39         if (mActionBar == null) {
40             mActionBar = mActivity.getActionBar();
41             mActionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
42         }
43     }
44 
45     @Override
addTab(CompatTab tab)46     public void addTab(CompatTab tab) {
47         String tag = tab.getTag();
48 
49         // Check to see if we already have a fragment for this tab, probably
50         // from a previously saved state.  If so, deactivate it, because our
51         // initial state is that a tab isn't shown.
52 
53         Fragment fragment = mActivity.getSupportFragmentManager().findFragmentByTag(tag);
54         tab.setFragment(fragment);
55 
56         if (fragment != null && !fragment.isDetached()) {
57             FragmentTransaction ft = mActivity.getSupportFragmentManager().beginTransaction();
58             ft.detach(fragment);
59             ft.commit();
60         }
61 
62         if (tab.getCallback() == null) {
63             throw new IllegalStateException("CompatTab must have a CompatTabListener");
64         }
65 
66         // We know tab is a CompatTabHoneycomb instance, so its
67         // native tab object is an ActionBar.Tab.
68         mActionBar.addTab((ActionBar.Tab) tab.getTab());
69     }
70 
71     @Override
onSaveInstanceState(Bundle outState)72     protected void onSaveInstanceState(Bundle outState) {
73         int position = mActionBar.getSelectedTab().getPosition();
74         outState.putInt("tab_position", position);
75     }
76 
77     @Override
onRestoreInstanceState(Bundle savedInstanceState)78     protected void onRestoreInstanceState(Bundle savedInstanceState) {
79         int position = savedInstanceState.getInt("tab_position");
80         mActionBar.setSelectedNavigationItem(position);
81     }
82 }
83