FragmentTabsPager.java

/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.pyload.android.client.components;

import java.util.ArrayList;

import org.pyload.android.client.R;
import org.pyload.android.client.pyLoadApp;

import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
import android.view.View;
import android.view.Window;
import android.widget.TabHost;

/**
 * Demonstrates combining a TabHost with a ViewPager to implement a tab UI that
 * switches between tabs and also allows the user to perform horizontal flicks
 * to move between the tabs.
 */
public class FragmentTabsPager extends FragmentActivity {
	protected TabHost mTabHost;
	protected ViewPager mViewPager;
	protected TabsAdapter mTabsAdapter;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
        if (!pyLoadApp.isActionBarAvailable()) {
		    requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
        }

		setContentView(R.layout.fragment_tabs_pager);
		mTabHost = (TabHost) findViewById(android.R.id.tabhost);
		mTabHost.setup();

		mViewPager = (ViewPager) findViewById(R.id.pager);

		mTabsAdapter = new TabsAdapter(this, mTabHost, mViewPager);

		if (savedInstanceState != null) {
			mTabHost.setCurrentTabByTag(savedInstanceState.getString("tab"));
		}
	}

	@Override
	protected void onSaveInstanceState(Bundle outState) {
		super.onSaveInstanceState(outState);
		outState.putString("tab", mTabHost.getCurrentTabTag());
	}

	public int getCurrentTab() {
		return mTabHost.getCurrentTab();
	}

	public Fragment getCurrentFragment() {
		return mTabsAdapter.getFragment(getCurrentTab());
	}
	
	
	/**
	 * 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 static 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>();
		private int selected = 0;

		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);
		
			Fragment frag = Fragment.instantiate(mContext,
					info.clss.getName(), info.args);
			
			((TabHandler) frag).setPosition(position);
			
			return frag;
		}
	
	
		@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) {
			
			Fragment pos = getFragment(position);
			if (pos != null)
				((TabHandler) pos).onSelected();

			Fragment old = getFragment(selected);
			if (old != null && selected != position)
				((TabHandler) old).onDeselected();

			mTabHost.setCurrentTab(position);
			selected = position;
		}

		@Override
		public void onPageScrollStateChanged(int state) {
		}
	}
}