com.lillicoder.lib.uiwidgets.tabs.FragmentTabsAdapter.java Source code

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Here is the source code for com.lillicoder.lib.uiwidgets.tabs.FragmentTabsAdapter.java

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/*
 * 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.
 */

/**
 * Copyright 2012 Scott Weeden-Moody
 *
 * This file has been modified from the FragmentTabs.java sample provided in the framework.
 * This class was made stand alone and was modified to work across Honeycomb versions.
 */

package com.lillicoder.lib.uiwidgets.tabs;

import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;

import junit.framework.Assert;
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.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TabHost;
import android.widget.TabHost.OnTabChangeListener;
import android.widget.TabHost.TabContentFactory;
import android.widget.TabHost.TabSpec;
import android.widget.TabWidget;

/**
 * Class that handles manipulation of a {@link TabHost} and a {@link ViewPager} in
 * conjunction to provide page-able tabs. This code is taken directly from a Google API
 * sample from v4 of the support library.
 */
public class FragmentTabsAdapter extends FragmentPagerAdapter implements OnTabChangeListener, OnPageChangeListener {

    private final Context _context;
    private final Map<String, TabInfo> _tabs;
    private final TabHost _tabHost;
    private final ViewPager _viewPager;

    /**
     * Class that creates dummy tabs for a {@link TabHost}.
     */
    private final class DummyTabFactory implements TabContentFactory {

        private final Context _context;

        public DummyTabFactory(Context context) {
            this._context = context;
        }

        @Override
        public View createTabContent(String tag) {
            View view = new View(this._context);
            view.setMinimumWidth(0);
            view.setMinimumHeight(0);
            return view;
        }

    }

    /**
     * Creates a new {@link FragmentTabsAdapter} instance.
     * @param activity {@link FragmentActivity} containing the tabs and pager.
     * @param tabHost {@link TabHost} to display the tabs.
     * @param pager {@link ViewPager} that provides the paging ability.
     */
    public FragmentTabsAdapter(FragmentActivity activity, TabHost tabHost, ViewPager pager) {
        super(activity.getSupportFragmentManager());

        this._context = activity;
        this._tabHost = tabHost;
        this._viewPager = pager;

        this._tabs = new LinkedHashMap<String, TabInfo>();

        this._tabHost.setOnTabChangedListener(this);
        this._viewPager.setAdapter(this);
        this._viewPager.setOnPageChangeListener(this);
    }

    /**
     * Adds a tab to the tab host with the given parameters.
     * @param tabSpec {@link TabSpec} to add as a tab.
     * @param aClass Class to serve as the fragment content for this tab.
     * @param args {@link Bundle} arguments.
     */
    public void addTab(TabSpec tabSpec, Class<?> aClass, Bundle args) {
        tabSpec.setContent(new DummyTabFactory(this._context));
        String tag = tabSpec.getTag();

        TabInfo info = new TabInfo(tag, aClass, args);
        this._tabs.put(tag, info);
        this._tabHost.addTab(tabSpec);

        this.notifyDataSetChanged();
    }

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

    @Override
    public Fragment getItem(int position) {
        TabInfo info = this.getTabInfoByPosition(position);
        Fragment fragment = Fragment.instantiate(this._context, info.getFragmentClassName(), info.getArguments());
        return fragment;
    }

    /**
     * Gets the {@link TabInfo} at the given position.
     * @param position Position of the {@link TabInfo} to fetch.
     * @return {@link TabInfo} at the given position,
     *          <code>null</code> if no value was found at that position.
     */
    private TabInfo getTabInfoByPosition(int position) {
        Assert.assertTrue(position >= 0);

        int index = position;
        for (Entry<String, TabInfo> entry : this._tabs.entrySet()) {
            if (index == 0)
                return (TabInfo) entry.getValue();
            else
                index -= 1;
        }

        return null;
    }

    @Override
    public void onPageScrollStateChanged(int state) {
    }

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

    @Override
    public void onPageSelected(int position) {
        // According to the sample comments, the TabHost
        // will automatically put focus on the current tab
        // when the tab changes, thus taking focus from the
        // ViewPager. This code functions as a workaround to
        // prevent this behavior by getting the current focus
        // state, disabling focus change for descendant views,
        // then restoring the old focus state.
        TabWidget widget = this._tabHost.getTabWidget();
        int oldFocusability = widget.getDescendantFocusability();
        widget.setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS);

        this._tabHost.setCurrentTab(position);

        widget.setDescendantFocusability(oldFocusability);
    }

    @Override
    public void onTabChanged(String tabId) {
        int position = this._tabHost.getCurrentTab();
        this._viewPager.setCurrentItem(position);
    }

}