Android Open Source - sigimera-android-app Tabs Adapter

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License

The source code is released under:

GNU General Public License

Java Source Code

package org.sigimera.app.android;
/**//  ww w. java  2 s  .c  om
 * Safe Travel - Android Client
 * Copyright (C) 2013 by Sigimera Ltd.
 * All Rights Reserved
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc., 51
 * Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

import java.util.ArrayList;

import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.view.ViewPager;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TabHost;
import android.widget.TabWidget;

/**
 * This is a helper class that implements the management of tabs and all
 * details of connecting a ViewPager with associated TabHost. It relies on a
 * trick. Normally a tab host has a simple API for supplying a View or
 * Intent that each tab will show. This is not sufficient for switching
 * between pages. So instead we make the content part of the tab host 0dp
 * high (it is not shown) and the TabsAdapter supplies its own dummy view to
 * show as the tab content. It listens to changes in tabs, and takes care of
 * switch to the correct paged in the ViewPager whenever the selected tab
 * changes.
 */
public class TabsAdapter extends FragmentPagerAdapter implements
    TabHost.OnTabChangeListener, ViewPager.OnPageChangeListener {
  
  private final Context mContext;
  private final TabHost mTabHost;
  private final ViewPager mViewPager;
  private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();

  static final class TabInfo {
    // private final String tag;
    private final Class<?> clss;
    private final Bundle args;

    TabInfo(String _tag, Class<?> _class, Bundle _args) {
      // tag = _tag;
      clss = _class;
      args = _args;
    }
  }

  static class DummyTabFactory implements TabHost.TabContentFactory {
    private final Context mContext;

    public DummyTabFactory(Context context) {
      mContext = context;
    }

    @Override
    public View createTabContent(String tag) {
      View v = new View(mContext);
      v.setMinimumWidth(0);
      v.setMinimumHeight(0);
      return v;
    }
  }

  public TabsAdapter(FragmentActivity activity, TabHost tabHost,
      ViewPager pager) {
    super(activity.getSupportFragmentManager());
    mContext = activity;
    mTabHost = tabHost;
    mViewPager = pager;
    mTabHost.setOnTabChangedListener(this);
    mViewPager.setAdapter(this);
    mViewPager.setOnPageChangeListener(this);
  }

  public void addTab(TabHost.TabSpec tabSpec, Class<?> clss, Bundle args) {
    tabSpec.setContent(new DummyTabFactory(mContext));
    String tag = tabSpec.getTag();

    TabInfo info = new TabInfo(tag, clss, args);
    mTabs.add(info);
    mTabHost.addTab(tabSpec);
    notifyDataSetChanged();
  }

  @Override
  public int getCount() {
    return mTabs.size();
  }

  @Override
  public Fragment getItem(int position) {
    TabInfo info = mTabs.get(position);
    return Fragment.instantiate(mContext, info.clss.getName(),
        info.args);
  }

  @Override
  public void onTabChanged(String tabId) {
    int position = mTabHost.getCurrentTab();
    mViewPager.setCurrentItem(position);
  }

  @Override
  public void onPageScrolled(int position, float positionOffset,
      int positionOffsetPixels) {
  }

  @Override
  public void onPageSelected(int position) {
    // Unfortunately when TabHost changes the current tab, it kindly
    // also takes care of putting focus on it when not in touch mode.
    // The jerk.
    // This hack tries to prevent this from pulling focus out of our
    // ViewPager.
    TabWidget widget = mTabHost.getTabWidget();
    int oldFocusability = widget.getDescendantFocusability();
    widget.setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS);
    mTabHost.setCurrentTab(position);
    widget.setDescendantFocusability(oldFocusability);
  }

  @Override
  public void onPageScrollStateChanged(int state) {
  }

  @Override
  public void destroyItem(ViewGroup container, int position, Object object) {
    super.destroyItem(container, position, object);
    FragmentManager manager = ((Fragment) object).getFragmentManager();
    FragmentTransaction trans = manager.beginTransaction();
    trans.remove((Fragment) object);
    trans.commit();
  }
}

Java Source Code List

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