content: /*
   * Copyright (C) 2010 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.actionbarsherlock.app;
  
  import android.content.Context;
  import android.content.res.TypedArray;
  import android.graphics.drawable.Drawable;
  import android.support.v4.app.FragmentTransaction;
  import android.util.AttributeSet;
  import android.view.Gravity;
  import android.view.View;
  import android.view.ViewDebug;
  import android.view.ViewGroup;
  import android.view.ViewGroup.MarginLayoutParams;
  import android.widget.SpinnerAdapter;
  
  /**
   * A window feature at the top of the activity that may display the activity title, navigation
   * modes, and other interactive items.
   * <p>Beginning with Android 3.0 (API level 11), the action bar appears at the top of an
   * activity's window when the activity uses the system's {@link
   * android.R.style#Theme_Holo Holo} theme (or one of its descendant themes), which is the default.
   * You may otherwise add the action bar by calling {@link
   * android.view.Window#requestFeature requestFeature(FEATURE_ACTION_BAR)} or by declaring it in a
   * custom theme with the {@link android.R.styleable#Theme_windowActionBar windowActionBar} property.
   * <p>By default, the action bar shows the application icon on
   * the left, followed by the activity title. If your activity has an options menu, you can make
   * select items accessible directly from the action bar as "action items". You can also
   * modify various characteristics of the action bar or remove it completely.</p>
   * <p>From your activity, you can retrieve an instance of {@link ActionBar} by calling {@link
   * android.app.Activity#getActionBar getActionBar()}.</p>
   * <p>In some cases, the action bar may be overlayed by another bar that enables contextual actions,
   * using an {@link android.view.ActionMode}. For example, when the user selects one or more items in
   * your activity, you can enable an action mode that offers actions specific to the selected
   * items, with a UI that temporarily replaces the action bar. Although the UI may occupy the
   * same space, the {@link android.view.ActionMode} APIs are distinct and independent from those for
   * {@link ActionBar}.
   * <div class="special reference">
   * <h3>Developer Guides</h3>
   * <p>For information about how to use the action bar, including how to add action items, navigation
   * modes and more, read the <a href="{@docRoot}guide/topics/ui/actionbar.html">Action
   * Bar</a> developer guide.</p>
   * </div>
   */
  public abstract class ActionBar {
      /**
       * Standard navigation mode. Consists of either a logo or icon
       * and title text with an optional subtitle. Clicking any of these elements
       * will dispatch onOptionsItemSelected to the host Activity with
       * a MenuItem with item ID android.R.id.home.
       */
      public static final int NAVIGATION_MODE_STANDARD = android.app.ActionBar.NAVIGATION_MODE_STANDARD;
  
      /**
       * List navigation mode. Instead of static title text this mode
       * presents a list menu for navigation within the activity.
       * e.g. this might be presented to the user as a dropdown list.
       */
      public static final int NAVIGATION_MODE_LIST = android.app.ActionBar.NAVIGATION_MODE_LIST;
  
      /**
       * Tab navigation mode. Instead of static title text this mode
       * presents a series of tabs for navigation within the activity.
       */
      public static final int NAVIGATION_MODE_TABS = android.app.ActionBar.NAVIGATION_MODE_TABS;
  
      /**
       * Use logo instead of icon if available. This flag will cause appropriate
       * navigation modes to use a wider logo in place of the standard icon.
       *
       * @see #setDisplayOptions(int)
       * @see #setDisplayOptions(int, int)
       */
      public static final int DISPLAY_USE_LOGO = android.app.ActionBar.DISPLAY_USE_LOGO;
  
      /**
       * Show 'home' elements in this action bar, leaving more space for other
       * navigation elements. This includes logo and icon.
       *
       * @see #setDisplayOptions(int)
       * @see #setDisplayOptions(int, int)
       */
      public static final int DISPLAY_SHOW_HOME = android.app.ActionBar.DISPLAY_SHOW_HOME;
  
      /**
       * Display the 'home' element such that it appears as an 'up' affordance.
       * e.g. show an arrow to the left indicating the action that will be taken.
       *
       * Set this flag if selecting the 'home' button in the action bar to return
       * up by a single level in your UI rather than back to the top level or front page.
       *
       * <p>Setting this option will implicitly enable interaction with the home/up
       * button. See {@link #setHomeButtonEnabled(boolean)}.
       *
       * @see #setDisplayOptions(int)
       * @see #setDisplayOptions(int, int)
       */
      public static final int DISPLAY_HOME_AS_UP = android.app.ActionBar.DISPLAY_HOME_AS_UP;
  
      /**
       * Show the activity title and subtitle, if present.
       *
       * @see #setTitle(CharSequence)
       * @see #setTitle(int)
       * @see #setSubtitle(CharSequence)
       * @see #setSubtitle(int)
       * @see #setDisplayOptions(int)
       * @see #setDisplayOptions(int, int)
       */
      public static final int DISPLAY_SHOW_TITLE = android.app.ActionBar.DISPLAY_SHOW_TITLE;
  
      /**
       * Show the custom view if one has been set.
       * @see #setCustomView(View)
       * @see #setDisplayOptions(int)
       * @see #setDisplayOptions(int, int)
       */
      public static final int DISPLAY_SHOW_CUSTOM = android.app.ActionBar.DISPLAY_SHOW_CUSTOM;
  
      /**
       * Set the action bar into custom navigation mode, supplying a view
       * for custom navigation.
       *
       * Custom navigation views appear between the application icon and
       * any action buttons and may use any space available there. Common
       * use cases for custom navigation views might include an auto-suggesting
       * address bar for a browser or other navigation mechanisms that do not
       * translate well to provided navigation modes.
       *
       * @param view Custom navigation view to place in the ActionBar.
       */
      public abstract void setCustomView(View view);
  
      /**
       * Set the action bar into custom navigation mode, supplying a view
       * for custom navigation.
       *
       * <p>Custom navigation views appear between the application icon and
       * any action buttons and may use any space available there. Common
       * use cases for custom navigation views might include an auto-suggesting
       * address bar for a browser or other navigation mechanisms that do not
       * translate well to provided navigation modes.</p>
       *
       * <p>The display option {@link #DISPLAY_SHOW_CUSTOM} must be set for
       * the custom view to be displayed.</p>
       *
       * @param view Custom navigation view to place in the ActionBar.
       * @param layoutParams How this custom view should layout in the bar.
       *
       * @see #setDisplayOptions(int, int)
       */
      public abstract void setCustomView(View view, LayoutParams layoutParams);
  
      /**
       * Set the action bar into custom navigation mode, supplying a view
       * for custom navigation.
       *
       * <p>Custom navigation views appear between the application icon and
       * any action buttons and may use any space available there. Common
       * use cases for custom navigation views might include an auto-suggesting
       * address bar for a browser or other navigation mechanisms that do not
       * translate well to provided navigation modes.</p>
       *
       * <p>The display option {@link #DISPLAY_SHOW_CUSTOM} must be set for
       * the custom view to be displayed.</p>
       *
       * @param resId Resource ID of a layout to inflate into the ActionBar.
       *
       * @see #setDisplayOptions(int, int)
       */
      public abstract void setCustomView(int resId);
  
      /**
       * Set the icon to display in the 'home' section of the action bar.
       * The action bar will use an icon specified by its style or the
       * activity icon by default.
       *
       * Whether the home section shows an icon or logo is controlled
       * by the display option {@link #DISPLAY_USE_LOGO}.
       *
       * @param resId Resource ID of a drawable to show as an icon.
       *
       * @see #setDisplayUseLogoEnabled(boolean)
       * @see #setDisplayShowHomeEnabled(boolean)
       */
      public abstract void setIcon(int resId);
  
      /**
       * Set the icon to display in the 'home' section of the action bar.
       * The action bar will use an icon specified by its style or the
       * activity icon by default.
       *
       * Whether the home section shows an icon or logo is controlled
       * by the display option {@link #DISPLAY_USE_LOGO}.
       *
       * @param icon Drawable to show as an icon.
       *
       * @see #setDisplayUseLogoEnabled(boolean)
       * @see #setDisplayShowHomeEnabled(boolean)
       */
      public abstract void setIcon(Drawable icon);
  
      /**
       * Set the logo to display in the 'home' section of the action bar.
       * The action bar will use a logo specified by its style or the
       * activity logo by default.
       *
       * Whether the home section shows an icon or logo is controlled
       * by the display option {@link #DISPLAY_USE_LOGO}.
       *
       * @param resId Resource ID of a drawable to show as a logo.
       *
       * @see #setDisplayUseLogoEnabled(boolean)
       * @see #setDisplayShowHomeEnabled(boolean)
       */
      public abstract void setLogo(int resId);
  
      /**
       * Set the logo to display in the 'home' section of the action bar.
       * The action bar will use a logo specified by its style or the
       * activity logo by default.
       *
       * Whether the home section shows an icon or logo is controlled
       * by the display option {@link #DISPLAY_USE_LOGO}.
       *
       * @param logo Drawable to show as a logo.
       *
       * @see #setDisplayUseLogoEnabled(boolean)
       * @see #setDisplayShowHomeEnabled(boolean)
       */
      public abstract void setLogo(Drawable logo);
  
      /**
       * Set the adapter and navigation callback for list navigation mode.
       *
       * The supplied adapter will provide views for the expanded list as well as
       * the currently selected item. (These may be displayed differently.)
       *
       * The supplied OnNavigationListener will alert the application when the user
       * changes the current list selection.
       *
       * @param adapter An adapter that will provide views both to display
       *                the current navigation selection and populate views
       *                within the dropdown navigation menu.
       * @param callback An OnNavigationListener that will receive events when the user
       *                 selects a navigation item.
       */
      public abstract void setListNavigationCallbacks(SpinnerAdapter adapter,
              OnNavigationListener callback);
  
      /**
       * Set the selected navigation item in list or tabbed navigation modes.
       *
       * @param position Position of the item to select.
       */
      public abstract void setSelectedNavigationItem(int position);
  
      /**
       * Get the position of the selected navigation item in list or tabbed navigation modes.
       *
       * @return Position of the selected item.
       */
      public abstract int getSelectedNavigationIndex();
  
      /**
       * Get the number of navigation items present in the current navigation mode.
       *
       * @return Number of navigation items.
       */
      public abstract int getNavigationItemCount();
  
      /**
       * Set the action bar's title. This will only be displayed if
       * {@link #DISPLAY_SHOW_TITLE} is set.
       *
       * @param title Title to set
       *
       * @see #setTitle(int)
       * @see #setDisplayOptions(int, int)
       */
      public abstract void setTitle(CharSequence title);
  
      /**
       * Set the action bar's title. This will only be displayed if
       * {@link #DISPLAY_SHOW_TITLE} is set.
       *
       * @param resId Resource ID of title string to set
       *
       * @see #setTitle(CharSequence)
       * @see #setDisplayOptions(int, int)
       */
      public abstract void setTitle(int resId);
  
      /**
       * Set the action bar's subtitle. This will only be displayed if
       * {@link #DISPLAY_SHOW_TITLE} is set. Set to null to disable the
       * subtitle entirely.
       *
       * @param subtitle Subtitle to set
       *
       * @see #setSubtitle(int)
       * @see #setDisplayOptions(int, int)
       */
      public abstract void setSubtitle(CharSequence subtitle);
  
      /**
       * Set the action bar's subtitle. This will only be displayed if
       * {@link #DISPLAY_SHOW_TITLE} is set.
       *
       * @param resId Resource ID of subtitle string to set
       *
       * @see #setSubtitle(CharSequence)
       * @see #setDisplayOptions(int, int)
       */
      public abstract void setSubtitle(int resId);
  
      /**
       * Set display options. This changes all display option bits at once. To change
       * a limited subset of display options, see {@link #setDisplayOptions(int, int)}.
       *
       * @param options A combination of the bits defined by the DISPLAY_ constants
       *                defined in ActionBar.
       */
      public abstract void setDisplayOptions(int options);
  
      /**
       * Set selected display options. Only the options specified by mask will be changed.
       * To change all display option bits at once, see {@link #setDisplayOptions(int)}.
       *
       * <p>Example: setDisplayOptions(0, DISPLAY_SHOW_HOME) will disable the
       * {@link #DISPLAY_SHOW_HOME} option.
       * setDisplayOptions(DISPLAY_SHOW_HOME, DISPLAY_SHOW_HOME | DISPLAY_USE_LOGO)
       * will enable {@link #DISPLAY_SHOW_HOME} and disable {@link #DISPLAY_USE_LOGO}.
       *
       * @param options A combination of the bits defined by the DISPLAY_ constants
       *                defined in ActionBar.
       * @param mask A bit mask declaring which display options should be changed.
       */
      public abstract void setDisplayOptions(int options, int mask);
  
      /**
       * Set whether to display the activity logo rather than the activity icon.
       * A logo is often a wider, more detailed image.
       *
       * <p>To set several display options at once, see the setDisplayOptions methods.
       *
       * @param useLogo true to use the activity logo, false to use the activity icon.
       *
       * @see #setDisplayOptions(int)
       * @see #setDisplayOptions(int, int)
       */
      public abstract void setDisplayUseLogoEnabled(boolean useLogo);
  
      /**
       * Set whether to include the application home affordance in the action bar.
       * Home is presented as either an activity icon or logo.
       *
       * <p>To set several display options at once, see the setDisplayOptions methods.
       *
       * @param showHome true to show home, false otherwise.
       *
       * @see #setDisplayOptions(int)
       * @see #setDisplayOptions(int, int)
       */
      public abstract void setDisplayShowHomeEnabled(boolean showHome);
  
      /**
       * Set whether home should be displayed as an "up" affordance.
       * Set this to true if selecting "home" returns up by a single level in your UI
       * rather than back to the top level or front page.
       *
       * <p>To set several display options at once, see the setDisplayOptions methods.
       *
       * @param showHomeAsUp true to show the user that selecting home will return one
       *                     level up rather than to the top level of the app.
       *
       * @see #setDisplayOptions(int)
       * @see #setDisplayOptions(int, int)
       */
      public abstract void setDisplayHomeAsUpEnabled(boolean showHomeAsUp);
  
      /**
       * Set whether an activity title/subtitle should be displayed.
       *
       * <p>To set several display options at once, see the setDisplayOptions methods.
       *
       * @param showTitle true to display a title/subtitle if present.
       *
       * @see #setDisplayOptions(int)
       * @see #setDisplayOptions(int, int)
       */
      public abstract void setDisplayShowTitleEnabled(boolean showTitle);
  
      /**
       * Set whether a custom view should be displayed, if set.
       *
       * <p>To set several display options at once, see the setDisplayOptions methods.
       *
       * @param showCustom true if the currently set custom view should be displayed, false otherwise.
       *
       * @see #setDisplayOptions(int)
       * @see #setDisplayOptions(int, int)
       */
      public abstract void setDisplayShowCustomEnabled(boolean showCustom);
  
      /**
       * Set the ActionBar's background. This will be used for the primary
       * action bar.
       *
       * @param d Background drawable
       * @see #setStackedBackgroundDrawable(Drawable)
       * @see #setSplitBackgroundDrawable(Drawable)
       */
      public abstract void setBackgroundDrawable(Drawable d);
  
      /**
       * Set the ActionBar's stacked background. This will appear
       * in the second row/stacked bar on some devices and configurations.
       *
       * @param d Background drawable for the stacked row
       */
      public void setStackedBackgroundDrawable(Drawable d) { }
  
      /**
       * Set the ActionBar's split background. This will appear in
       * the split action bar containing menu-provided action buttons
       * on some devices and configurations.
       * <p>You can enable split action bar with {@link android.R.attr#uiOptions}
       *
       * @param d Background drawable for the split bar
       */
      public void setSplitBackgroundDrawable(Drawable d) { }
  
      /**
       * @return The current custom view.
       */
      public abstract View getCustomView();
  
      /**
       * Returns the current ActionBar title in standard mode.
       * Returns null if {@link #getNavigationMode()} would not return
       * {@link #NAVIGATION_MODE_STANDARD}.
       *
       * @return The current ActionBar title or null.
       */
      public abstract CharSequence getTitle();
  
      /**
       * Returns the current ActionBar subtitle in standard mode.
       * Returns null if {@link #getNavigationMode()} would not return
       * {@link #NAVIGATION_MODE_STANDARD}.
       *
       * @return The current ActionBar subtitle or null.
       */
      public abstract CharSequence getSubtitle();
  
      /**
       * Returns the current navigation mode. The result will be one of:
       * <ul>
       * <li>{@link #NAVIGATION_MODE_STANDARD}</li>
       * <li>{@link #NAVIGATION_MODE_LIST}</li>
       * <li>{@link #NAVIGATION_MODE_TABS}</li>
       * </ul>
       *
       * @return The current navigation mode.
       */
      public abstract int getNavigationMode();
  
      /**
       * Set the current navigation mode.
       *
       * @param mode The new mode to set.
       * @see #NAVIGATION_MODE_STANDARD
       * @see #NAVIGATION_MODE_LIST
       * @see #NAVIGATION_MODE_TABS
       */
      public abstract void setNavigationMode(int mode);
  
      /**
       * @return The current set of display options.
       */
      public abstract int getDisplayOptions();
  
      /**
       * Create and return a new {@link Tab}.
       * This tab will not be included in the action bar until it is added.
       *
       * <p>Very often tabs will be used to switch between {@link Fragment}
       * objects.  Here is a typical implementation of such tabs:</p>
       *
       * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentTabs.java
       *      complete}
       *
       * @return A new Tab
       *
       * @see #addTab(Tab)
       */
      public abstract Tab newTab();
  
      /**
       * Add a tab for use in tabbed navigation mode. The tab will be added at the end of the list.
       * If this is the first tab to be added it will become the selected tab.
       *
       * @param tab Tab to add
       */
      public abstract void addTab(Tab tab);
  
      /**
       * Add a tab for use in tabbed navigation mode. The tab will be added at the end of the list.
       *
       * @param tab Tab to add
       * @param setSelected True if the added tab should become the selected tab.
       */
      public abstract void addTab(Tab tab, boolean setSelected);
  
      /**
       * Add a tab for use in tabbed navigation mode. The tab will be inserted at
       * <code>position</code>. If this is the first tab to be added it will become
       * the selected tab.
       *
       * @param tab The tab to add
       * @param position The new position of the tab
       */
      public abstract void addTab(Tab tab, int position);
  
      /**
       * Add a tab for use in tabbed navigation mode. The tab will be insterted at
       * <code>position</code>.
       *
       * @param tab The tab to add
       * @param position The new position of the tab
       * @param setSelected True if the added tab should become the selected tab.
       */
      public abstract void addTab(Tab tab, int position, boolean setSelected);
  
      /**
       * Remove a tab from the action bar. If the removed tab was selected it will be deselected
       * and another tab will be selected if present.
       *
       * @param tab The tab to remove
       */
      public abstract void removeTab(Tab tab);
  
      /**
       * Remove a tab from the action bar. If the removed tab was selected it will be deselected
       * and another tab will be selected if present.
       *
       * @param position Position of the tab to remove
       */
      public abstract void removeTabAt(int position);
  
      /**
       * Remove all tabs from the action bar and deselect the current tab.
       */
      public abstract void removeAllTabs();
  
      /**
       * Select the specified tab. If it is not a child of this action bar it will be added.
       *
       * <p>Note: If you want to select by index, use {@link #setSelectedNavigationItem(int)}.</p>
       *
       * @param tab Tab to select
       */
      public abstract void selectTab(Tab tab);
  
      /**
       * Returns the currently selected tab if in tabbed navigation mode and there is at least
       * one tab present.
       *
       * @return The currently selected tab or null
       */
      public abstract Tab getSelectedTab();
  
      /**
       * Returns the tab at the specified index.
       *
       * @param index Index value in the range 0-get
       * @return
       */
      public abstract Tab getTabAt(int index);
  
      /**
       * Returns the number of tabs currently registered with the action bar.
       * @return Tab count
       */
      public abstract int getTabCount();
  
      /**
       * Retrieve the current height of the ActionBar.
       *
       * @return The ActionBar's height
       */
      public abstract int getHeight();
  
      /**
       * Show the ActionBar if it is not currently showing.
       * If the window hosting the ActionBar does not have the feature
       * {@link Window#FEATURE_ACTION_BAR_OVERLAY} it will resize application
       * content to fit the new space available.
       */
      public abstract void show();
  
      /**
       * Hide the ActionBar if it is currently showing.
       * If the window hosting the ActionBar does not have the feature
       * {@link Window#FEATURE_ACTION_BAR_OVERLAY} it will resize application
       * content to fit the new space available.
       */
      public abstract void hide();
  
      /**
       * @return <code>true</code> if the ActionBar is showing, <code>false</code> otherwise.
       */
      public abstract boolean isShowing();
  
      /**
       * Add a listener that will respond to menu visibility change events.
       *
       * @param listener The new listener to add
       */
      public abstract void addOnMenuVisibilityListener(OnMenuVisibilityListener listener);
  
      /**
       * Remove a menu visibility listener. This listener will no longer receive menu
       * visibility change events.
       *
       * @param listener A listener to remove that was previously added
       */
      public abstract void removeOnMenuVisibilityListener(OnMenuVisibilityListener listener);
  
      /**
       * Enable or disable the "home" button in the corner of the action bar. (Note that this
       * is the application home/up affordance on the action bar, not the systemwide home
       * button.)
       *
       * <p>This defaults to true for packages targeting &lt; API 14. For packages targeting
       * API 14 or greater, the application should call this method to enable interaction
       * with the home/up affordance.
       *
       * <p>Setting the {@link #DISPLAY_HOME_AS_UP} display option will automatically enable
       * the home button.
       *
       * @param enabled true to enable the home button, false to disable the home button.
       */
      public void setHomeButtonEnabled(boolean enabled) { }
  
      /**
       * Returns a {@link Context} with an appropriate theme for creating views that
       * will appear in the action bar. If you are inflating or instantiating custom views
       * that will appear in an action bar, you should use the Context returned by this method.
       * (This includes adapters used for list navigation mode.)
       * This will ensure that views contrast properly against the action bar.
       *
       * @return A themed Context for creating views
       */
      public Context getThemedContext() { return null; }
  
      /**
       * Listener interface for ActionBar navigation events.
       */
      public interface OnNavigationListener {
          /**
           * This method is called whenever a navigation item in your action bar
           * is selected.
           *
           * @param itemPosition Position of the item clicked.
           * @param itemId ID of the item clicked.
           * @return True if the event was handled, false otherwise.
           */
          public boolean onNavigationItemSelected(int itemPosition, long itemId);
      }
  
      /**
       * Listener for receiving events when action bar menus are shown or hidden.
       */
      public interface OnMenuVisibilityListener {
          /**
           * Called when an action bar menu is shown or hidden. Applications may want to use
           * this to tune auto-hiding behavior for the action bar or pause/resume video playback,
           * gameplay, or other activity within the main content area.
           *
           * @param isVisible True if an action bar menu is now visible, false if no action bar
           *                  menus are visible.
           */
          public void onMenuVisibilityChanged(boolean isVisible);
      }
  
      /**
       * A tab in the action bar.
       *
       * <p>Tabs manage the hiding and showing of {@link Fragment}s.
       */
      public static abstract class Tab {
          /**
           * An invalid position for a tab.
           *
           * @see #getPosition()
           */
          public static final int INVALID_POSITION = -1;
  
          /**
           * Return the current position of this tab in the action bar.
           *
           * @return Current position, or {@link #INVALID_POSITION} if this tab is not currently in
           *         the action bar.
           */
          public abstract int getPosition();
  
          /**
           * Return the icon associated with this tab.
           *
           * @return The tab's icon
           */
          public abstract Drawable getIcon();
  
          /**
           * Return the text of this tab.
           *
           * @return The tab's text
           */
          public abstract CharSequence getText();
  
          /**
           * Set the icon displayed on this tab.
           *
           * @param icon The drawable to use as an icon
           * @return The current instance for call chaining
           */
          public abstract Tab setIcon(Drawable icon);
  
          /**
           * Set the icon displayed on this tab.
           *
           * @param resId Resource ID referring to the drawable to use as an icon
           * @return The current instance for call chaining
           */
          public abstract Tab setIcon(int resId);
  
          /**
           * Set the text displayed on this tab. Text may be truncated if there is not
           * room to display the entire string.
           *
           * @param text The text to display
           * @return The current instance for call chaining
           */
          public abstract Tab setText(CharSequence text);
  
          /**
           * Set the text displayed on this tab. Text may be truncated if there is not
           * room to display the entire string.
           *
           * @param resId A resource ID referring to the text that should be displayed
           * @return The current instance for call chaining
           */
          public abstract Tab setText(int resId);
  
          /**
           * Set a custom view to be used for this tab. This overrides values set by
           * {@link #setText(CharSequence)} and {@link #setIcon(Drawable)}.
           *
           * @param view Custom view to be used as a tab.
           * @return The current instance for call chaining
           */
          public abstract Tab setCustomView(View view);
  
          /**
           * Set a custom view to be used for this tab. This overrides values set by
           * {@link #setText(CharSequence)} and {@link #setIcon(Drawable)}.
           *
           * @param layoutResId A layout resource to inflate and use as a custom tab view
           * @return The current instance for call chaining
           */
          public abstract Tab setCustomView(int layoutResId);
  
          /**
           * Retrieve a previously set custom view for this tab.
           *
           * @return The custom view set by {@link #setCustomView(View)}.
           */
          public abstract View getCustomView();
  
          /**
           * Give this Tab an arbitrary object to hold for later use.
           *
           * @param obj Object to store
           * @return The current instance for call chaining
           */
          public abstract Tab setTag(Object obj);
  
          /**
           * @return This Tab's tag object.
           */
          public abstract Object getTag();
  
          /**
           * Set the {@link TabListener} that will handle switching to and from this tab.
           * All tabs must have a TabListener set before being added to the ActionBar.
           *
           * @param listener Listener to handle tab selection events
           * @return The current instance for call chaining
           */
          public abstract Tab setTabListener(TabListener listener);
  
          /**
           * Select this tab. Only valid if the tab has been added to the action bar.
           */
          public abstract void select();
  
          /**
           * Set a description of this tab's content for use in accessibility support.
           * If no content description is provided the title will be used.
           *
           * @param resId A resource ID referring to the description text
           * @return The current instance for call chaining
           * @see #setContentDescription(CharSequence)
           * @see #getContentDescription()
           */
          public abstract Tab setContentDescription(int resId);
  
          /**
           * Set a description of this tab's content for use in accessibility support.
           * If no content description is provided the title will be used.
           *
           * @param contentDesc Description of this tab's content
           * @return The current instance for call chaining
           * @see #setContentDescription(int)
           * @see #getContentDescription()
           */
          public abstract Tab setContentDescription(CharSequence contentDesc);
  
          /**
           * Gets a brief description of this tab's content for use in accessibility support.
           *
           * @return Description of this tab's content
           * @see #setContentDescription(CharSequence)
           * @see #setContentDescription(int)
           */
          public abstract CharSequence getContentDescription();
      }
  
      /**
       * Callback interface invoked when a tab is focused, unfocused, added, or removed.
       */
      public interface TabListener {
          /**
           * Called when a tab enters the selected state.
           *
           * @param tab The tab that was selected
           * @param ft A {@link FragmentTransaction} for queuing fragment operations to execute
           *        during a tab switch. The previous tab's unselect and this tab's select will be
           *        executed in a single transaction. This FragmentTransaction does not support
           *        being added to the back stack.
           */
          public void onTabSelected(Tab tab, FragmentTransaction ft);
  
          /**
           * Called when a tab exits the selected state.
           *
           * @param tab The tab that was unselected
           * @param ft A {@link FragmentTransaction} for queuing fragment operations to execute
           *        during a tab switch. This tab's unselect and the newly selected tab's select
           *        will be executed in a single transaction. This FragmentTransaction does not
           *        support being added to the back stack.
           */
          public void onTabUnselected(Tab tab, FragmentTransaction ft);
  
          /**
           * Called when a tab that is already selected is chosen again by the user.
           * Some applications may use this action to return to the top level of a category.
           *
           * @param tab The tab that was reselected.
           * @param ft A {@link FragmentTransaction} for queuing fragment operations to execute
           *        once this method returns. This FragmentTransaction does not support
           *        being added to the back stack.
           */
          public void onTabReselected(Tab tab, FragmentTransaction ft);
      }
  
      /**
       * Per-child layout information associated with action bar custom views.
       *
       * @attr ref android.R.styleable#ActionBar_LayoutParams_layout_gravity
       */
      public static class LayoutParams extends MarginLayoutParams {
          private static final int[] ATTRS = new int[] {
                  android.R.attr.layout_gravity
          };
  
          /**
           * Gravity for the view associated with these LayoutParams.
           *
           * @see android.view.Gravity
           */
          @ViewDebug.ExportedProperty(mapping = {
              @ViewDebug.IntToString(from =  -1,                       to = "NONE"),
              @ViewDebug.IntToString(from = Gravity.NO_GRAVITY,        to = "NONE"),
              @ViewDebug.IntToString(from = Gravity.TOP,               to = "TOP"),
              @ViewDebug.IntToString(from = Gravity.BOTTOM,            to = "BOTTOM"),
              @ViewDebug.IntToString(from = Gravity.LEFT,              to = "LEFT"),
              @ViewDebug.IntToString(from = Gravity.RIGHT,             to = "RIGHT"),
              @ViewDebug.IntToString(from = Gravity.CENTER_VERTICAL,   to = "CENTER_VERTICAL"),
              @ViewDebug.IntToString(from = Gravity.FILL_VERTICAL,     to = "FILL_VERTICAL"),
              @ViewDebug.IntToString(from = Gravity.CENTER_HORIZONTAL, to = "CENTER_HORIZONTAL"),
              @ViewDebug.IntToString(from = Gravity.FILL_HORIZONTAL,   to = "FILL_HORIZONTAL"),
              @ViewDebug.IntToString(from = Gravity.CENTER,            to = "CENTER"),
              @ViewDebug.IntToString(from = Gravity.FILL,              to = "FILL")
          })
          public int gravity = -1;
  
          public LayoutParams(Context c, AttributeSet attrs) {
              super(c, attrs);
  
              TypedArray a = c.obtainStyledAttributes(attrs, ATTRS);
              gravity = a.getInt(0, -1);
              a.recycle();
          }
  
          public LayoutParams(int width, int height) {
              super(width, height);
              this.gravity = Gravity.CENTER_VERTICAL | Gravity.LEFT;
          }
  
          public LayoutParams(int width, int height, int gravity) {
              super(width, height);
              this.gravity = gravity;
          }
  
          public LayoutParams(int gravity) {
              this(WRAP_CONTENT, FILL_PARENT, gravity);
          }
  
          public LayoutParams(LayoutParams source) {
              super(source);
  
              this.gravity = source.gravity;
          }
  
          public LayoutParams(ViewGroup.LayoutParams source) {
              super(source);
          }
      }
  }
  