src/com/android/deskclock/worldclock/CitySelectionActivity.java - platform/packages/apps/DeskClock - Gitiles

 /*
  * Copyright (C) 2015 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 com.android.deskclock.worldclock;

 import android.content.Context;
 import android.media.AudioManager;
 import android.os.Bundle;
 import android.support.v7.widget.SearchView;
 import android.text.TextUtils;
 import android.text.format.DateFormat;
 import android.util.ArraySet;
 import android.util.TypedValue;
 import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.BaseAdapter;
 import android.widget.CheckBox;
 import android.widget.CompoundButton;
 import android.widget.ListView;
 import android.widget.SectionIndexer;
 import android.widget.TextView;

 import com.android.deskclock.BaseActivity;
 import com.android.deskclock.R;
 import com.android.deskclock.Utils;
 import com.android.deskclock.actionbarmenu.AbstractMenuItemController;
 import com.android.deskclock.actionbarmenu.ActionBarMenuManager;
 import com.android.deskclock.actionbarmenu.MenuItemControllerFactory;
 import com.android.deskclock.actionbarmenu.NavUpMenuItemController;
 import com.android.deskclock.actionbarmenu.SearchMenuItemController;
 import com.android.deskclock.actionbarmenu.SettingMenuItemController;
 import com.android.deskclock.data.City;
 import com.android.deskclock.data.DataModel;

 import java.util.ArrayList;
 import java.util.Calendar;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 import java.util.Locale;
 import java.util.Set;
 import java.util.TimeZone;

 /**
  * This activity allows the user to alter the cities selected for display.
  *
  * Note, it is possible for two instances of this Activity to exist simultaneously:
  *
  * <ul>
  *     <li>Clock Tab-> Tap Floating Action Button</li>
  *     <li>Digital Widget -> Tap any city clock</li>
  * </ul>
  *
  * As a result, {@link #onResume()} conservatively refreshes itself from the backing
  * {@link DataModel} which may have changed since this activity was last displayed.
  */
 public final class CitySelectionActivity extends BaseActivity {

     /** The list of all selected and unselected cities, indexed and possibly filtered. */
     private ListView mCitiesList;

     /** The adapter that presents all of the selected and unselected cities. */
     private CityAdapter mCitiesAdapter;

     /** Manages all action bar menu display and click handling. */
     private final ActionBarMenuManager mActionBarMenuManager = new ActionBarMenuManager(this);

     /** Menu item controller for search view. */
     private SearchMenuItemController mSearchMenuItemController;

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setVolumeControlStream(AudioManager.STREAM_ALARM);

         setContentView(R.layout.cities_activity);
         mSearchMenuItemController =
                 new SearchMenuItemController(new SearchView.OnQueryTextListener() {
                     @Override
                     public boolean onQueryTextSubmit(String query) {
                         return false;
                     }

                     @Override
                     public boolean onQueryTextChange(String query) {
                         mCitiesAdapter.filter(query);
                         updateFastScrolling();
                         return true;
                     }
                 }, savedInstanceState);
         mCitiesAdapter = new CityAdapter(this, mSearchMenuItemController);
         mActionBarMenuManager.addMenuItemController(new NavUpMenuItemController(this))
                 .addMenuItemController(mSearchMenuItemController)
                 .addMenuItemController(new SortOrderMenuItemController())
                 .addMenuItemController(new SettingMenuItemController(this))
                 .addMenuItemController(MenuItemControllerFactory.getInstance()
                         .buildMenuItemControllers(this));
         mCitiesList = (ListView) findViewById(R.id.cities_list);
         mCitiesList.setScrollBarStyle(View.SCROLLBARS_INSIDE_INSET);
         mCitiesList.setAdapter(mCitiesAdapter);

         updateFastScrolling();
     }

     @Override
     public void onSaveInstanceState(Bundle bundle) {
         super.onSaveInstanceState(bundle);
         mSearchMenuItemController.saveInstance(bundle);
     }

     @Override
     public void onResume() {
         super.onResume();

         // Recompute the contents of the adapter before displaying on screen.
         mCitiesAdapter.refresh();
     }

     @Override
     public void onPause() {
         super.onPause();

         // Save the selected cities.
         DataModel.getDataModel().setSelectedCities(mCitiesAdapter.getSelectedCities());
     }

     @Override
     public boolean onCreateOptionsMenu(Menu menu) {
         mActionBarMenuManager.createOptionsMenu(menu, getMenuInflater());
         return true;
     }

     @Override
     public boolean onPrepareOptionsMenu(Menu menu) {
         mActionBarMenuManager.prepareShowMenu(menu);
         return true;
     }

     @Override
     public boolean onOptionsItemSelected(MenuItem item) {
         if (mActionBarMenuManager.handleMenuItemClick(item)) {
             return true;
         }
         return super.onOptionsItemSelected(item);
     }

     /**
      * Fast scrolling is only enabled while no filtering is happening.
      */
     private void updateFastScrolling() {
         final boolean enabled = !mCitiesAdapter.isFiltering();
         mCitiesList.setFastScrollAlwaysVisible(enabled);
         mCitiesList.setFastScrollEnabled(enabled);
     }

     /**
      * This adapter presents data in 2 possible modes. If selected cities exist the format is:
      *
      * <pre>
      * Selected Cities
      *   City 1 (alphabetically first)
      *   City 2 (alphabetically second)
      *   ...
      * A City A1 (alphabetically first starting with A)
      *   City A2 (alphabetically second starting with A)
      *   ...
      * B City B1 (alphabetically first starting with B)
      *   City B2 (alphabetically second starting with B)
      *   ...
      * </pre>
      *
      * If selected cities do not exist, that section is removed and all that remains is:
      *
      * <pre>
      * A City A1 (alphabetically first starting with A)
      *   City A2 (alphabetically second starting with A)
      *   ...
      * B City B1 (alphabetically first starting with B)
      *   City B2 (alphabetically second starting with B)
      *   ...
      * </pre>
      */
     private static final class CityAdapter extends BaseAdapter implements View.OnClickListener,
             CompoundButton.OnCheckedChangeListener, SectionIndexer {

         /** The type of the single optional "Selected Cities" header entry. */
         private static final int VIEW_TYPE_SELECTED_CITIES_HEADER = 0;

         /** The type of each city entry. */
         private static final int VIEW_TYPE_CITY = 1;

         private final Context mContext;

         private final LayoutInflater mInflater;

         /** The 12-hour time pattern for the current locale. */
         private final String mPattern12;

         /** The 24-hour time pattern for the current locale. */
         private final String mPattern24;

         /** {@code true} time should honor {@link #mPattern24}; {@link #mPattern12} otherwise. */
         private boolean mIs24HoursMode;

         /** A calendar used to format time in a particular timezone. */
         private final Calendar mCalendar;

         /** The list of cities which may be filtered by a search term. */
         private List<City> mFilteredCities = Collections.emptyList();

         /** A mutable set of cities currently selected by the user. */
         private final Set<City> mUserSelectedCities = new ArraySet<>();

         /** The number of user selections at the top of the adapter to avoid indexing. */
         private int mOriginalUserSelectionCount;

         /** The precomputed section headers. */
         private String[] mSectionHeaders;

         /** The corresponding location of each precomputed section header. */
         private Integer[] mSectionHeaderPositions;

         /** Menu item controller for search. Search query is maintained here. */
         private final SearchMenuItemController mSearchMenuItemController;

         public CityAdapter(Context context, SearchMenuItemController searchMenuItemController) {
             mContext = context;
             mSearchMenuItemController = searchMenuItemController;
             mInflater = LayoutInflater.from(context);

             mCalendar = Calendar.getInstance();
             mCalendar.setTimeInMillis(System.currentTimeMillis());

             final Locale locale = Locale.getDefault();
             mPattern24 = DateFormat.getBestDateTimePattern(locale, "Hm");

             String pattern12 = DateFormat.getBestDateTimePattern(locale, "hma");
             if (TextUtils.getLayoutDirectionFromLocale(locale) == View.LAYOUT_DIRECTION_RTL) {
                 // There's an RTL layout bug that causes jank when fast-scrolling through
                 // the list in 12-hour mode in an RTL locale. We can work around this by
                 // ensuring the strings are the same length by using "hh" instead of "h".
                 pattern12 = pattern12.replaceAll("h", "hh");
             }
             mPattern12 = pattern12;
         }

         @Override
         public int getCount() {
             final int headerCount = hasHeader() ? 1 : 0;
             return headerCount + mFilteredCities.size();
         }

         @Override
         public City getItem(int position) {
             if (hasHeader()) {
                 final int itemViewType = getItemViewType(position);
                 switch (itemViewType) {
                     case VIEW_TYPE_SELECTED_CITIES_HEADER:
                         return null;
                     case VIEW_TYPE_CITY:
                         return mFilteredCities.get(position - 1);
                 }
                 throw new IllegalStateException("unexpected item view type: " + itemViewType);
             }

             return mFilteredCities.get(position);
         }

         @Override
         public long getItemId(int position) {
             return position;
         }

         @Override
         public synchronized View getView(int position, View view, ViewGroup parent) {
             final int itemViewType = getItemViewType(position);
             switch (itemViewType) {
                 case VIEW_TYPE_SELECTED_CITIES_HEADER:
                     if (view == null) {
                         view = mInflater.inflate(R.layout.city_list_header, parent, false);
                     }
                     return view;

                 case VIEW_TYPE_CITY:
                     final City city = getItem(position);
                     final TimeZone timeZone = city.getTimeZone();

                     // Inflate a new view if necessary.
                     if (view == null) {
                         view = mInflater.inflate(R.layout.city_list_item, parent, false);
                         final TextView index = (TextView) view.findViewById(R.id.index);
                         final TextView name = (TextView) view.findViewById(R.id.city_name);
                         final TextView time = (TextView) view.findViewById(R.id.city_time);
                         final CheckBox selected = (CheckBox) view.findViewById(R.id.city_onoff);
                         view.setTag(new CityItemHolder(index, name, time, selected));
                     }

                     // Bind data into the child views.
                     final CityItemHolder holder = (CityItemHolder) view.getTag();
                     holder.selected.setTag(city);
                     holder.selected.setChecked(mUserSelectedCities.contains(city));
                     holder.selected.setContentDescription(city.getName());
                     holder.selected.setOnCheckedChangeListener(this);
                     holder.name.setText(city.getName(), TextView.BufferType.SPANNABLE);
                     holder.time.setText(getTimeCharSequence(timeZone));

                     final boolean showIndex = getShowIndex(position);
                     holder.index.setVisibility(showIndex ? View.VISIBLE : View.INVISIBLE);
                     if (showIndex) {
                         switch (getCitySort()) {
                             case NAME:
                                 holder.index.setText(city.getIndexString());
                                 holder.index.setTextSize(TypedValue.COMPLEX_UNIT_SP, 24);
                                 break;

                             case UTC_OFFSET:
                                 holder.index.setText(Utils.getGMTHourOffset(timeZone, false));
                                 holder.index.setTextSize(TypedValue.COMPLEX_UNIT_SP, 14);
                                 break;
                         }
                     }

                     // skip checkbox and other animations
                     view.jumpDrawablesToCurrentState();
                     view.setOnClickListener(this);
                     return view;
             }

             throw new IllegalStateException("unexpected item view type: " + itemViewType);
         }

         @Override
         public int getViewTypeCount() {
             return 2;
         }

         @Override
         public int getItemViewType(int position) {
             return hasHeader() && position == 0 ? VIEW_TYPE_SELECTED_CITIES_HEADER : VIEW_TYPE_CITY;
         }

         @Override
         public void onCheckedChanged(CompoundButton b, boolean checked) {
             final City city = (City) b.getTag();
             if (checked) {
                 mUserSelectedCities.add(city);
                 b.announceForAccessibility(mContext.getString(R.string.city_checked,
                         city.getName()));
             } else {
                 mUserSelectedCities.remove(city);
                 b.announceForAccessibility(mContext.getString(R.string.city_unchecked,
                         city.getName()));
             }
         }

         @Override
         public void onClick(View v) {
             final CheckBox b = (CheckBox) v.findViewById(R.id.city_onoff);
             b.setChecked(!b.isChecked());
         }

         @Override
         public Object[] getSections() {
             if (mSectionHeaders == null) {
                 // Make an educated guess at the expected number of sections.
                 final int approximateSectionCount = getCount() / 5;
                 final List<String> sections = new ArrayList<>(approximateSectionCount);
                 final List<Integer> positions = new ArrayList<>(approximateSectionCount);

                 // Add a section for the "Selected Cities" header if it exists.
                 if (hasHeader()) {
                     sections.add("+");
                     positions.add(0);
                 }

                 for (int position = 0; position < getCount(); position++) {
                     // Add a section if this position should show the section index.
                     if (getShowIndex(position)) {
                         final City city = getItem(position);
                         switch (getCitySort()) {
                             case NAME:
                                 sections.add(city.getIndexString());
                                 break;
                             case UTC_OFFSET:
                                 final TimeZone timezone = city.getTimeZone();
                                 sections.add(Utils.getGMTHourOffset(timezone, Utils.isPreL()));
                                 break;
                         }
                         positions.add(position);
                     }
                 }

                 mSectionHeaders = sections.toArray(new String[sections.size()]);
                 mSectionHeaderPositions = positions.toArray(new Integer[positions.size()]);
             }
             return mSectionHeaders;
         }

         @Override
         public int getPositionForSection(int sectionIndex) {
             return getSections().length == 0 ? 0 : mSectionHeaderPositions[sectionIndex];
         }

         @Override
         public int getSectionForPosition(int position) {
             if (getSections().length == 0) {
                 return 0;
             }

             for (int i = 0; i < mSectionHeaderPositions.length - 2; i++) {
                 if (position < mSectionHeaderPositions[i]) continue;
                 if (position >= mSectionHeaderPositions[i + 1]) continue;

                 return i;
             }

             return mSectionHeaderPositions.length - 1;
         }

         /**
          * Clear the section headers to force them to be recomputed if they are now stale.
          */
         private void clearSectionHeaders() {
             mSectionHeaders = null;
             mSectionHeaderPositions = null;
         }

         /**
          * Rebuilds all internal data structures from scratch.
          */
         private void refresh() {
             // Update the 12/24 hour mode.
             mIs24HoursMode = DateFormat.is24HourFormat(mContext);

             // Refresh the user selections.
             final List<City> selected = DataModel.getDataModel().getSelectedCities();
             mUserSelectedCities.clear();
             mUserSelectedCities.addAll(selected);
             mOriginalUserSelectionCount = selected.size();

             // Recompute section headers.
             clearSectionHeaders();

             // Recompute filtered cities.
             filter(mSearchMenuItemController.getQueryText());
         }

         /**
          * Filter the cities using the given {@code queryText}.
          */
         private void filter(String queryText) {
             mSearchMenuItemController.setQueryText(queryText);
             final String query = queryText.trim().toUpperCase();

             // Compute the filtered list of cities.
             final List<City> filteredCities;
             if (TextUtils.isEmpty(query)) {
                 filteredCities = DataModel.getDataModel().getAllCities();
             } else {
                 final List<City> unselected = DataModel.getDataModel().getUnselectedCities();
                 filteredCities = new ArrayList<>(unselected.size());
                 for (City city : unselected) {
                     if (city.getNameUpperCase().startsWith(query)) {
                         filteredCities.add(city);
                     }
                 }
             }

             // Swap in the filtered list of cities and notify of the data change.
             mFilteredCities = filteredCities;
             notifyDataSetChanged();
         }

         private boolean isFiltering() {
             return !TextUtils.isEmpty(mSearchMenuItemController.getQueryText().trim());
         }

         private Collection<City> getSelectedCities() { return mUserSelectedCities; }
         private boolean hasHeader() { return !isFiltering() && mOriginalUserSelectionCount > 0; }

         private DataModel.CitySort getCitySort() {
             return DataModel.getDataModel().getCitySort();
         }

         private Comparator<City> getCitySortComparator() {
             return DataModel.getDataModel().getCityIndexComparator();
         }

         private CharSequence getTimeCharSequence(TimeZone timeZone) {
             mCalendar.setTimeZone(timeZone);
             return DateFormat.format(mIs24HoursMode ? mPattern24 : mPattern12, mCalendar);
         }

         private boolean getShowIndex(int position) {
             // Indexes are never displayed on filtered cities.
             if (isFiltering()) {
                 return false;
             }

             if (hasHeader()) {
                 // None of the original user selections should show their index.
                 if (position <= mOriginalUserSelectionCount) {
                     return false;
                 }

                 // The first item after the original user selections must always show its index.
                 if (position == mOriginalUserSelectionCount + 1) {
                     return true;
                 }
             } else {
                 // None of the original user selections should show their index.
                 if (position < mOriginalUserSelectionCount) {
                     return false;
                 }

                 // The first item after the original user selections must always show its index.
                 if (position == mOriginalUserSelectionCount) {
                     return true;
                 }
             }

             // Otherwise compare the city with its predecessor to test if it is a header.
             final City priorCity = getItem(position - 1);
             final City city = getItem(position);
             return getCitySortComparator().compare(priorCity, city) != 0;
         }

         /**
          * Cache the child views of each city item view.
          */
         private static final class CityItemHolder {

             private final TextView index;
             private final TextView name;
             private final TextView time;
             private final CheckBox selected;

             public CityItemHolder(TextView index, TextView name, TextView time, CheckBox selected) {
                 this.index = index;
                 this.name = name;
                 this.time = time;
                 this.selected = selected;
             }
         }
     }

     private final class SortOrderMenuItemController extends AbstractMenuItemController {

         private static final int SORT_MENU_RES_ID = R.id.menu_item_sort;

         @Override
         public int getId() {
             return SORT_MENU_RES_ID;
         }

         @Override
         public void showMenuItem(Menu menu) {
             final MenuItem sortMenuItem = menu.findItem(SORT_MENU_RES_ID);
             final String title;
             if (DataModel.getDataModel().getCitySort() == DataModel.CitySort.NAME) {
                 title = getString(R.string.menu_item_sort_by_gmt_offset);
             } else {
                 title = getString(R.string.menu_item_sort_by_name);
             }
             sortMenuItem.setTitle(title);
             sortMenuItem.setVisible(true);
         }

         @Override
         public boolean handleMenuItemClick(MenuItem item) {
             // Save the new sort order.
             DataModel.getDataModel().toggleCitySort();

             // Section headers are influenced by sort order and must be cleared.
             mCitiesAdapter.clearSectionHeaders();

             // Honor the new sort order in the adapter.
             mCitiesAdapter.filter(mSearchMenuItemController.getQueryText());
             return true;
         }
     }
 }
	/*
	* Copyright (C) 2015 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 com.android.deskclock.worldclock;

	import android.content.Context;
	import android.media.AudioManager;
	import android.os.Bundle;
	import android.support.v7.widget.SearchView;
	import android.text.TextUtils;
	import android.text.format.DateFormat;
	import android.util.ArraySet;
	import android.util.TypedValue;
	import android.view.LayoutInflater;
	import android.view.Menu;
	import android.view.MenuItem;
	import android.view.View;
	import android.view.ViewGroup;
	import android.widget.BaseAdapter;
	import android.widget.CheckBox;
	import android.widget.CompoundButton;
	import android.widget.ListView;
	import android.widget.SectionIndexer;
	import android.widget.TextView;

	import com.android.deskclock.BaseActivity;
	import com.android.deskclock.R;
	import com.android.deskclock.Utils;
	import com.android.deskclock.actionbarmenu.AbstractMenuItemController;
	import com.android.deskclock.actionbarmenu.ActionBarMenuManager;
	import com.android.deskclock.actionbarmenu.MenuItemControllerFactory;
	import com.android.deskclock.actionbarmenu.NavUpMenuItemController;
	import com.android.deskclock.actionbarmenu.SearchMenuItemController;
	import com.android.deskclock.actionbarmenu.SettingMenuItemController;
	import com.android.deskclock.data.City;
	import com.android.deskclock.data.DataModel;

	import java.util.ArrayList;
	import java.util.Calendar;
	import java.util.Collection;
	import java.util.Collections;
	import java.util.Comparator;
	import java.util.List;
	import java.util.Locale;
	import java.util.Set;
	import java.util.TimeZone;

	/**
	* This activity allows the user to alter the cities selected for display.
	*
	* Note, it is possible for two instances of this Activity to exist simultaneously:
	*
	* <ul>
	* <li>Clock Tab-> Tap Floating Action Button</li>
	* <li>Digital Widget -> Tap any city clock</li>
	* </ul>
	*
	* As a result, {@link #onResume()} conservatively refreshes itself from the backing
	* {@link DataModel} which may have changed since this activity was last displayed.
	*/
	public final class CitySelectionActivity extends BaseActivity {

	/** The list of all selected and unselected cities, indexed and possibly filtered. */
	private ListView mCitiesList;

	/** The adapter that presents all of the selected and unselected cities. */
	private CityAdapter mCitiesAdapter;

	/** Manages all action bar menu display and click handling. */
	private final ActionBarMenuManager mActionBarMenuManager = new ActionBarMenuManager(this);

	/** Menu item controller for search view. */
	private SearchMenuItemController mSearchMenuItemController;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	setVolumeControlStream(AudioManager.STREAM_ALARM);

	setContentView(R.layout.cities_activity);
	mSearchMenuItemController =
	new SearchMenuItemController(new SearchView.OnQueryTextListener() {
	@Override
	public boolean onQueryTextSubmit(String query) {
	return false;
	}

	@Override
	public boolean onQueryTextChange(String query) {
	mCitiesAdapter.filter(query);
	updateFastScrolling();
	return true;
	}
	}, savedInstanceState);
	mCitiesAdapter = new CityAdapter(this, mSearchMenuItemController);
	mActionBarMenuManager.addMenuItemController(new NavUpMenuItemController(this))
	.addMenuItemController(mSearchMenuItemController)
	.addMenuItemController(new SortOrderMenuItemController())
	.addMenuItemController(new SettingMenuItemController(this))
	.addMenuItemController(MenuItemControllerFactory.getInstance()
	.buildMenuItemControllers(this));
	mCitiesList = (ListView) findViewById(R.id.cities_list);
	mCitiesList.setScrollBarStyle(View.SCROLLBARS_INSIDE_INSET);
	mCitiesList.setAdapter(mCitiesAdapter);

	updateFastScrolling();
	}

	@Override
	public void onSaveInstanceState(Bundle bundle) {
	super.onSaveInstanceState(bundle);
	mSearchMenuItemController.saveInstance(bundle);
	}

	@Override
	public void onResume() {
	super.onResume();

	// Recompute the contents of the adapter before displaying on screen.
	mCitiesAdapter.refresh();
	}

	@Override
	public void onPause() {
	super.onPause();

	// Save the selected cities.
	DataModel.getDataModel().setSelectedCities(mCitiesAdapter.getSelectedCities());
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
	mActionBarMenuManager.createOptionsMenu(menu, getMenuInflater());
	return true;
	}

	@Override
	public boolean onPrepareOptionsMenu(Menu menu) {
	mActionBarMenuManager.prepareShowMenu(menu);
	return true;
	}

	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
	if (mActionBarMenuManager.handleMenuItemClick(item)) {
	return true;
	}
	return super.onOptionsItemSelected(item);
	}

	/**
	* Fast scrolling is only enabled while no filtering is happening.
	*/
	private void updateFastScrolling() {
	final boolean enabled = !mCitiesAdapter.isFiltering();
	mCitiesList.setFastScrollAlwaysVisible(enabled);
	mCitiesList.setFastScrollEnabled(enabled);
	}

	/**
	* This adapter presents data in 2 possible modes. If selected cities exist the format is:
	*
	* <pre>
	* Selected Cities
	* City 1 (alphabetically first)
	* City 2 (alphabetically second)
	* ...
	* A City A1 (alphabetically first starting with A)
	* City A2 (alphabetically second starting with A)
	* ...
	* B City B1 (alphabetically first starting with B)
	* City B2 (alphabetically second starting with B)
	* ...
	* </pre>
	*
	* If selected cities do not exist, that section is removed and all that remains is:
	*
	* <pre>
	* A City A1 (alphabetically first starting with A)
	* City A2 (alphabetically second starting with A)
	* ...
	* B City B1 (alphabetically first starting with B)
	* City B2 (alphabetically second starting with B)
	* ...
	* </pre>
	*/
	private static final class CityAdapter extends BaseAdapter implements View.OnClickListener,
	CompoundButton.OnCheckedChangeListener, SectionIndexer {

	/** The type of the single optional "Selected Cities" header entry. */
	private static final int VIEW_TYPE_SELECTED_CITIES_HEADER = 0;

	/** The type of each city entry. */
	private static final int VIEW_TYPE_CITY = 1;

	private final Context mContext;

	private final LayoutInflater mInflater;

	/** The 12-hour time pattern for the current locale. */
	private final String mPattern12;

	/** The 24-hour time pattern for the current locale. */
	private final String mPattern24;

	/** {@code true} time should honor {@link #mPattern24}; {@link #mPattern12} otherwise. */
	private boolean mIs24HoursMode;

	/** A calendar used to format time in a particular timezone. */
	private final Calendar mCalendar;

	/** The list of cities which may be filtered by a search term. */
	private List<City> mFilteredCities = Collections.emptyList();

	/** A mutable set of cities currently selected by the user. */
	private final Set<City> mUserSelectedCities = new ArraySet<>();

	/** The number of user selections at the top of the adapter to avoid indexing. */
	private int mOriginalUserSelectionCount;

	/** The precomputed section headers. */
	private String[] mSectionHeaders;

	/** The corresponding location of each precomputed section header. */
	private Integer[] mSectionHeaderPositions;

	/** Menu item controller for search. Search query is maintained here. */
	private final SearchMenuItemController mSearchMenuItemController;

	public CityAdapter(Context context, SearchMenuItemController searchMenuItemController) {
	mContext = context;
	mSearchMenuItemController = searchMenuItemController;
	mInflater = LayoutInflater.from(context);

	mCalendar = Calendar.getInstance();
	mCalendar.setTimeInMillis(System.currentTimeMillis());

	final Locale locale = Locale.getDefault();
	mPattern24 = DateFormat.getBestDateTimePattern(locale, "Hm");

	String pattern12 = DateFormat.getBestDateTimePattern(locale, "hma");
	if (TextUtils.getLayoutDirectionFromLocale(locale) == View.LAYOUT_DIRECTION_RTL) {
	// There's an RTL layout bug that causes jank when fast-scrolling through
	// the list in 12-hour mode in an RTL locale. We can work around this by
	// ensuring the strings are the same length by using "hh" instead of "h".
	pattern12 = pattern12.replaceAll("h", "hh");
	}
	mPattern12 = pattern12;
	}

	@Override
	public int getCount() {
	final int headerCount = hasHeader() ? 1 : 0;
	return headerCount + mFilteredCities.size();
	}

	@Override
	public City getItem(int position) {
	if (hasHeader()) {
	final int itemViewType = getItemViewType(position);
	switch (itemViewType) {
	case VIEW_TYPE_SELECTED_CITIES_HEADER:
	return null;
	case VIEW_TYPE_CITY:
	return mFilteredCities.get(position - 1);
	}
	throw new IllegalStateException("unexpected item view type: " + itemViewType);
	}

	return mFilteredCities.get(position);
	}

	@Override
	public long getItemId(int position) {
	return position;
	}

	@Override
	public synchronized View getView(int position, View view, ViewGroup parent) {
	final int itemViewType = getItemViewType(position);
	switch (itemViewType) {
	case VIEW_TYPE_SELECTED_CITIES_HEADER:
	if (view == null) {
	view = mInflater.inflate(R.layout.city_list_header, parent, false);
	}
	return view;

	case VIEW_TYPE_CITY:
	final City city = getItem(position);
	final TimeZone timeZone = city.getTimeZone();

	// Inflate a new view if necessary.
	if (view == null) {
	view = mInflater.inflate(R.layout.city_list_item, parent, false);
	final TextView index = (TextView) view.findViewById(R.id.index);
	final TextView name = (TextView) view.findViewById(R.id.city_name);
	final TextView time = (TextView) view.findViewById(R.id.city_time);
	final CheckBox selected = (CheckBox) view.findViewById(R.id.city_onoff);
	view.setTag(new CityItemHolder(index, name, time, selected));
	}

	// Bind data into the child views.
	final CityItemHolder holder = (CityItemHolder) view.getTag();
	holder.selected.setTag(city);
	holder.selected.setChecked(mUserSelectedCities.contains(city));
	holder.selected.setContentDescription(city.getName());
	holder.selected.setOnCheckedChangeListener(this);
	holder.name.setText(city.getName(), TextView.BufferType.SPANNABLE);
	holder.time.setText(getTimeCharSequence(timeZone));

	final boolean showIndex = getShowIndex(position);
	holder.index.setVisibility(showIndex ? View.VISIBLE : View.INVISIBLE);
	if (showIndex) {
	switch (getCitySort()) {
	case NAME:
	holder.index.setText(city.getIndexString());
	holder.index.setTextSize(TypedValue.COMPLEX_UNIT_SP, 24);
	break;

	case UTC_OFFSET:
	holder.index.setText(Utils.getGMTHourOffset(timeZone, false));
	holder.index.setTextSize(TypedValue.COMPLEX_UNIT_SP, 14);
	break;
	}
	}

	// skip checkbox and other animations
	view.jumpDrawablesToCurrentState();
	view.setOnClickListener(this);
	return view;
	}

	throw new IllegalStateException("unexpected item view type: " + itemViewType);
	}

	@Override
	public int getViewTypeCount() {
	return 2;
	}

	@Override
	public int getItemViewType(int position) {
	return hasHeader() && position == 0 ? VIEW_TYPE_SELECTED_CITIES_HEADER : VIEW_TYPE_CITY;
	}

	@Override
	public void onCheckedChanged(CompoundButton b, boolean checked) {
	final City city = (City) b.getTag();
	if (checked) {
	mUserSelectedCities.add(city);
	b.announceForAccessibility(mContext.getString(R.string.city_checked,
	city.getName()));
	} else {
	mUserSelectedCities.remove(city);
	b.announceForAccessibility(mContext.getString(R.string.city_unchecked,
	city.getName()));
	}
	}

	@Override
	public void onClick(View v) {
	final CheckBox b = (CheckBox) v.findViewById(R.id.city_onoff);
	b.setChecked(!b.isChecked());
	}

	@Override
	public Object[] getSections() {
	if (mSectionHeaders == null) {
	// Make an educated guess at the expected number of sections.
	final int approximateSectionCount = getCount() / 5;
	final List<String> sections = new ArrayList<>(approximateSectionCount);
	final List<Integer> positions = new ArrayList<>(approximateSectionCount);

	// Add a section for the "Selected Cities" header if it exists.
	if (hasHeader()) {
	sections.add("+");
	positions.add(0);
	}

	for (int position = 0; position < getCount(); position++) {
	// Add a section if this position should show the section index.
	if (getShowIndex(position)) {
	final City city = getItem(position);
	switch (getCitySort()) {
	case NAME:
	sections.add(city.getIndexString());
	break;
	case UTC_OFFSET:
	final TimeZone timezone = city.getTimeZone();
	sections.add(Utils.getGMTHourOffset(timezone, Utils.isPreL()));
	break;
	}
	positions.add(position);
	}
	}

	mSectionHeaders = sections.toArray(new String[sections.size()]);
	mSectionHeaderPositions = positions.toArray(new Integer[positions.size()]);
	}
	return mSectionHeaders;
	}

	@Override
	public int getPositionForSection(int sectionIndex) {
	return getSections().length == 0 ? 0 : mSectionHeaderPositions[sectionIndex];
	}

	@Override
	public int getSectionForPosition(int position) {
	if (getSections().length == 0) {
	return 0;
	}

	for (int i = 0; i < mSectionHeaderPositions.length - 2; i++) {
	if (position < mSectionHeaderPositions[i]) continue;
	if (position >= mSectionHeaderPositions[i + 1]) continue;

	return i;
	}

	return mSectionHeaderPositions.length - 1;
	}

	/**
	* Clear the section headers to force them to be recomputed if they are now stale.
	*/
	private void clearSectionHeaders() {
	mSectionHeaders = null;
	mSectionHeaderPositions = null;
	}

	/**
	* Rebuilds all internal data structures from scratch.
	*/
	private void refresh() {
	// Update the 12/24 hour mode.
	mIs24HoursMode = DateFormat.is24HourFormat(mContext);

	// Refresh the user selections.
	final List<City> selected = DataModel.getDataModel().getSelectedCities();
	mUserSelectedCities.clear();
	mUserSelectedCities.addAll(selected);
	mOriginalUserSelectionCount = selected.size();

	// Recompute section headers.
	clearSectionHeaders();

	// Recompute filtered cities.
	filter(mSearchMenuItemController.getQueryText());
	}

	/**
	* Filter the cities using the given {@code queryText}.
	*/
	private void filter(String queryText) {
	mSearchMenuItemController.setQueryText(queryText);
	final String query = queryText.trim().toUpperCase();

	// Compute the filtered list of cities.
	final List<City> filteredCities;
	if (TextUtils.isEmpty(query)) {
	filteredCities = DataModel.getDataModel().getAllCities();
	} else {
	final List<City> unselected = DataModel.getDataModel().getUnselectedCities();
	filteredCities = new ArrayList<>(unselected.size());
	for (City city : unselected) {
	if (city.getNameUpperCase().startsWith(query)) {
	filteredCities.add(city);
	}
	}
	}

	// Swap in the filtered list of cities and notify of the data change.
	mFilteredCities = filteredCities;
	notifyDataSetChanged();
	}

	private boolean isFiltering() {
	return !TextUtils.isEmpty(mSearchMenuItemController.getQueryText().trim());
	}

	private Collection<City> getSelectedCities() { return mUserSelectedCities; }
	private boolean hasHeader() { return !isFiltering() && mOriginalUserSelectionCount > 0; }

	private DataModel.CitySort getCitySort() {
	return DataModel.getDataModel().getCitySort();
	}

	private Comparator<City> getCitySortComparator() {
	return DataModel.getDataModel().getCityIndexComparator();
	}

	private CharSequence getTimeCharSequence(TimeZone timeZone) {
	mCalendar.setTimeZone(timeZone);
	return DateFormat.format(mIs24HoursMode ? mPattern24 : mPattern12, mCalendar);
	}

	private boolean getShowIndex(int position) {
	// Indexes are never displayed on filtered cities.
	if (isFiltering()) {
	return false;
	}

	if (hasHeader()) {
	// None of the original user selections should show their index.
	if (position <= mOriginalUserSelectionCount) {
	return false;
	}

	// The first item after the original user selections must always show its index.
	if (position == mOriginalUserSelectionCount + 1) {
	return true;
	}
	} else {
	// None of the original user selections should show their index.
	if (position < mOriginalUserSelectionCount) {
	return false;
	}

	// The first item after the original user selections must always show its index.
	if (position == mOriginalUserSelectionCount) {
	return true;
	}
	}

	// Otherwise compare the city with its predecessor to test if it is a header.
	final City priorCity = getItem(position - 1);
	final City city = getItem(position);
	return getCitySortComparator().compare(priorCity, city) != 0;
	}

	/**
	* Cache the child views of each city item view.
	*/
	private static final class CityItemHolder {

	private final TextView index;
	private final TextView name;
	private final TextView time;
	private final CheckBox selected;

	public CityItemHolder(TextView index, TextView name, TextView time, CheckBox selected) {
	this.index = index;
	this.name = name;
	this.time = time;
	this.selected = selected;
	}
	}
	}

	private final class SortOrderMenuItemController extends AbstractMenuItemController {

	private static final int SORT_MENU_RES_ID = R.id.menu_item_sort;

	@Override
	public int getId() {
	return SORT_MENU_RES_ID;
	}

	@Override
	public void showMenuItem(Menu menu) {
	final MenuItem sortMenuItem = menu.findItem(SORT_MENU_RES_ID);
	final String title;
	if (DataModel.getDataModel().getCitySort() == DataModel.CitySort.NAME) {
	title = getString(R.string.menu_item_sort_by_gmt_offset);
	} else {
	title = getString(R.string.menu_item_sort_by_name);
	}
	sortMenuItem.setTitle(title);
	sortMenuItem.setVisible(true);
	}

	@Override
	public boolean handleMenuItemClick(MenuItem item) {
	// Save the new sort order.
	DataModel.getDataModel().toggleCitySort();

	// Section headers are influenced by sort order and must be cleared.
	mCitiesAdapter.clearSectionHeaders();

	// Honor the new sort order in the adapter.
	mCitiesAdapter.filter(mSearchMenuItemController.getQueryText());
	return true;
	}
	}
	}