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
17package com.example.android.tabcompat.lib;
18
19import android.app.ActionBar;
20import android.os.Bundle;
21import android.support.v4.app.Fragment;
22import android.support.v4.app.FragmentActivity;
23import 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 */
29public class TabHelperHoneycomb extends TabHelper {
30
31    ActionBar mActionBar;
32
33    protected TabHelperHoneycomb(FragmentActivity activity) {
34        super(activity);
35    }
36
37    @Override
38    protected void setUp() {
39        if (mActionBar == null) {
40            mActionBar = mActivity.getActionBar();
41            mActionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
42        }
43    }
44
45    @Override
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
72    protected void onSaveInstanceState(Bundle outState) {
73        int position = mActionBar.getSelectedTab().getPosition();
74        outState.putInt("tab_position", position);
75    }
76
77    @Override
78    protected void onRestoreInstanceState(Bundle savedInstanceState) {
79        int position = savedInstanceState.getInt("tab_position");
80        mActionBar.setSelectedNavigationItem(position);
81    }
82}
83