1 /*
2 **
3 ** Copyright 2013, The Android Open Source Project
4 **
5 ** Licensed under the Apache License, Version 2.0 (the "License");
6 ** you may not use this file except in compliance with the License.
7 ** You may obtain a copy of the License at
8 **
9 **     http://www.apache.org/licenses/LICENSE-2.0
10 **
11 ** Unless required by applicable law or agreed to in writing, software
12 ** distributed under the License is distributed on an "AS IS" BASIS,
13 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 ** See the License for the specific language governing permissions and
15 ** limitations under the License.
16 */
17 package com.android.packageinstaller;
18 
19 import android.app.Activity;
20 import android.content.Context;
21 import android.graphics.Rect;
22 import android.support.v4.view.PagerAdapter;
23 import android.support.v4.view.ViewPager;
24 import android.view.View;
25 import android.view.ViewGroup;
26 import android.widget.TabHost;
27 import android.widget.TabWidget;
28 
29 import java.util.ArrayList;
30 
31 /**
32  * This is a helper class that implements the management of tabs and all
33  * details of connecting a ViewPager with associated TabHost.  It relies on a
34  * trick.  Normally a tab host has a simple API for supplying a View or
35  * Intent that each tab will show.  This is not sufficient for switching
36  * between pages.  So instead we make the content part of the tab host
37  * 0dp high (it is not shown) and the TabsAdapter supplies its own dummy
38  * view to show as the tab content.  It listens to changes in tabs, and takes
39  * care of switch to the correct paged in the ViewPager whenever the selected
40  * tab changes.
41  */
42 public class TabsAdapter extends PagerAdapter
43         implements TabHost.OnTabChangeListener, ViewPager.OnPageChangeListener {
44     private final Context mContext;
45     private final TabHost mTabHost;
46     private final ViewPager mViewPager;
47     private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();
48     private final Rect mTempRect = new Rect();
49 
50     static final class TabInfo {
51         private final String tag;
52         private final View view;
53 
TabInfo(String _tag, View _view)54         TabInfo(String _tag, View _view) {
55             tag = _tag;
56             view = _view;
57         }
58     }
59 
60     static class DummyTabFactory implements TabHost.TabContentFactory {
61         private final Context mContext;
62 
DummyTabFactory(Context context)63         public DummyTabFactory(Context context) {
64             mContext = context;
65         }
66 
67         @Override
createTabContent(String tag)68         public View createTabContent(String tag) {
69             View v = new View(mContext);
70             v.setMinimumWidth(0);
71             v.setMinimumHeight(0);
72             return v;
73         }
74     }
75 
TabsAdapter(Activity activity, TabHost tabHost, ViewPager pager)76     public TabsAdapter(Activity activity, TabHost tabHost, ViewPager pager) {
77         mContext = activity;
78         mTabHost = tabHost;
79         mViewPager = pager;
80         mTabHost.setOnTabChangedListener(this);
81         mViewPager.setAdapter(this);
82         mViewPager.setOnPageChangeListener(this);
83     }
84 
addTab(TabHost.TabSpec tabSpec, View view)85     public void addTab(TabHost.TabSpec tabSpec, View view) {
86         tabSpec.setContent(new DummyTabFactory(mContext));
87         String tag = tabSpec.getTag();
88 
89         TabInfo info = new TabInfo(tag, view);
90         mTabs.add(info);
91         mTabHost.addTab(tabSpec);
92         notifyDataSetChanged();
93     }
94 
95     @Override
getCount()96     public int getCount() {
97         return mTabs.size();
98     }
99 
100     @Override
instantiateItem(ViewGroup container, int position)101     public Object instantiateItem(ViewGroup container, int position) {
102         View view = mTabs.get(position).view;
103         container.addView(view);
104         return view;
105     }
106 
107     @Override
destroyItem(ViewGroup container, int position, Object object)108     public void destroyItem(ViewGroup container, int position, Object object) {
109         container.removeView((View)object);
110     }
111 
112     @Override
isViewFromObject(View view, Object object)113     public boolean isViewFromObject(View view, Object object) {
114         return view == object;
115     }
116 
117     @Override
onTabChanged(String tabId)118     public void onTabChanged(String tabId) {
119         int position = mTabHost.getCurrentTab();
120         mViewPager.setCurrentItem(position);
121     }
122 
123     @Override
onPageScrolled(int position, float positionOffset, int positionOffsetPixels)124     public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
125     }
126 
127     @Override
onPageSelected(int position)128     public void onPageSelected(int position) {
129         // Unfortunately when TabHost changes the current tab, it kindly
130         // also takes care of putting focus on it when not in touch mode.
131         // The jerk.
132         // This hack tries to prevent this from pulling focus out of our
133         // ViewPager.
134         TabWidget widget = mTabHost.getTabWidget();
135         int oldFocusability = widget.getDescendantFocusability();
136         widget.setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS);
137         mTabHost.setCurrentTab(position);
138         widget.setDescendantFocusability(oldFocusability);
139 
140         // Scroll the current tab into visibility if needed.
141         View tab = widget.getChildTabViewAt(position);
142         mTempRect.set(tab.getLeft(), tab.getTop(), tab.getRight(), tab.getBottom());
143         widget.requestRectangleOnScreen(mTempRect, false);
144 
145         // Make sure the scrollbars are visible for a moment after selection
146         final View contentView = mTabs.get(position).view;
147         if (contentView instanceof CaffeinatedScrollView) {
148             ((CaffeinatedScrollView) contentView).awakenScrollBars();
149         }
150     }
151 
152     @Override
onPageScrollStateChanged(int state)153     public void onPageScrollStateChanged(int state) {
154     }
155 }
156