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     private TabHost.OnTabChangeListener mOnTabChangeListener;
50 
51     static final class TabInfo {
52         private final String tag;
53         private final View view;
54 
TabInfo(String _tag, View _view)55         TabInfo(String _tag, View _view) {
56             tag = _tag;
57             view = _view;
58         }
59     }
60 
61     static class DummyTabFactory implements TabHost.TabContentFactory {
62         private final Context mContext;
63 
DummyTabFactory(Context context)64         public DummyTabFactory(Context context) {
65             mContext = context;
66         }
67 
68         @Override
createTabContent(String tag)69         public View createTabContent(String tag) {
70             View v = new View(mContext);
71             v.setMinimumWidth(0);
72             v.setMinimumHeight(0);
73             return v;
74         }
75     }
76 
TabsAdapter(Activity activity, TabHost tabHost, ViewPager pager)77     public TabsAdapter(Activity activity, TabHost tabHost, ViewPager pager) {
78         mContext = activity;
79         mTabHost = tabHost;
80         mViewPager = pager;
81         mTabHost.setOnTabChangedListener(this);
82         mViewPager.setAdapter(this);
83         mViewPager.setOnPageChangeListener(this);
84     }
85 
addTab(TabHost.TabSpec tabSpec, View view)86     public void addTab(TabHost.TabSpec tabSpec, View view) {
87         tabSpec.setContent(new DummyTabFactory(mContext));
88         String tag = tabSpec.getTag();
89 
90         TabInfo info = new TabInfo(tag, view);
91         mTabs.add(info);
92         mTabHost.addTab(tabSpec);
93         notifyDataSetChanged();
94     }
95 
96     @Override
getCount()97     public int getCount() {
98         return mTabs.size();
99     }
100 
101     @Override
instantiateItem(ViewGroup container, int position)102     public Object instantiateItem(ViewGroup container, int position) {
103         View view = mTabs.get(position).view;
104         container.addView(view);
105         return view;
106     }
107 
108     @Override
destroyItem(ViewGroup container, int position, Object object)109     public void destroyItem(ViewGroup container, int position, Object object) {
110         container.removeView((View)object);
111     }
112 
113     @Override
isViewFromObject(View view, Object object)114     public boolean isViewFromObject(View view, Object object) {
115         return view == object;
116     }
117 
setOnTabChangedListener(TabHost.OnTabChangeListener listener)118     public void setOnTabChangedListener(TabHost.OnTabChangeListener listener) {
119         mOnTabChangeListener = listener;
120     }
121 
122     @Override
onTabChanged(String tabId)123     public void onTabChanged(String tabId) {
124         int position = mTabHost.getCurrentTab();
125         mViewPager.setCurrentItem(position);
126         if (mOnTabChangeListener != null) {
127             mOnTabChangeListener.onTabChanged(tabId);
128         }
129     }
130 
131     @Override
onPageScrolled(int position, float positionOffset, int positionOffsetPixels)132     public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
133     }
134 
135     @Override
onPageSelected(int position)136     public void onPageSelected(int position) {
137         // Unfortunately when TabHost changes the current tab, it kindly
138         // also takes care of putting focus on it when not in touch mode.
139         // The jerk.
140         // This hack tries to prevent this from pulling focus out of our
141         // ViewPager.
142         TabWidget widget = mTabHost.getTabWidget();
143         int oldFocusability = widget.getDescendantFocusability();
144         widget.setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS);
145         mTabHost.setCurrentTab(position);
146         widget.setDescendantFocusability(oldFocusability);
147 
148         // Scroll the current tab into visibility if needed.
149         View tab = widget.getChildTabViewAt(position);
150         mTempRect.set(tab.getLeft(), tab.getTop(), tab.getRight(), tab.getBottom());
151         widget.requestRectangleOnScreen(mTempRect, false);
152 
153         // Make sure the scrollbars are visible for a moment after selection
154         final View contentView = mTabs.get(position).view;
155         if (contentView instanceof CaffeinatedScrollView) {
156             ((CaffeinatedScrollView) contentView).awakenScrollBars();
157         }
158     }
159 
160     @Override
onPageScrollStateChanged(int state)161     public void onPageScrollStateChanged(int state) {
162     }
163 }
164