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      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 
     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 
     64         public DummyTabFactory(Context context) {
     65             mContext = context;
     66         }
     67 
     68         @Override
     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 
     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 
     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
     97     public int getCount() {
     98         return mTabs.size();
     99     }
    100 
    101     @Override
    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
    109     public void destroyItem(ViewGroup container, int position, Object object) {
    110         container.removeView((View)object);
    111     }
    112 
    113     @Override
    114     public boolean isViewFromObject(View view, Object object) {
    115         return view == object;
    116     }
    117 
    118     public void setOnTabChangedListener(TabHost.OnTabChangeListener listener) {
    119         mOnTabChangeListener = listener;
    120     }
    121 
    122     @Override
    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
    132     public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
    133     }
    134 
    135     @Override
    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
    161     public void onPageScrollStateChanged(int state) {
    162     }
    163 }
    164