content: /*
   * 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 com.actionbarsherlock.view;
  
  import android.content.Context;
  import android.view.View;
  
  /**
   * This class is a mediator for accomplishing a given task, for example sharing a file.
   * It is responsible for creating a view that performs an action that accomplishes the task.
   * This class also implements other functions such a performing a default action.
   * <p>
   * An ActionProvider can be optionally specified for a {@link MenuItem} and in such a
   * case it will be responsible for creating the action view that appears in the
   * {@link android.app.ActionBar} as a substitute for the menu item when the item is
   * displayed as an action item. Also the provider is responsible for performing a
   * default action if a menu item placed on the overflow menu of the ActionBar is
   * selected and none of the menu item callbacks has handled the selection. For this
   * case the provider can also optionally provide a sub-menu for accomplishing the
   * task at hand.
   * </p>
   * <p>
   * There are two ways for using an action provider for creating and handling of action views:
   * <ul>
   * <li>
   * Setting the action provider on a {@link MenuItem} directly by calling
   * {@link MenuItem#setActionProvider(ActionProvider)}.
   * </li>
   * <li>
   * Declaring the action provider in the menu XML resource. For example:
   * <pre>
   * <code>
   *   &lt;item android:id="@+id/my_menu_item"
   *     android:title="Title"
   *     android:icon="@drawable/my_menu_item_icon"
   *     android:showAsAction="ifRoom"
   *     android:actionProviderClass="foo.bar.SomeActionProvider" /&gt;
   * </code>
   * </pre>
   * </li>
   * </ul>
   * </p>
   *
   * @see MenuItem#setActionProvider(ActionProvider)
   * @see MenuItem#getActionProvider()
   */
  public abstract class ActionProvider {
      private SubUiVisibilityListener mSubUiVisibilityListener;
  
      /**
       * Creates a new instance.
       *
       * @param context Context for accessing resources.
       */
      public ActionProvider(Context context) {
      }
  
      /**
       * Factory method for creating new action views.
       *
       * @return A new action view.
       */
      public abstract View onCreateActionView();
  
      /**
       * Performs an optional default action.
       * <p>
       * For the case of an action provider placed in a menu item not shown as an action this
       * method is invoked if previous callbacks for processing menu selection has handled
       * the event.
       * </p>
       * <p>
       * A menu item selection is processed in the following order:
       * <ul>
       * <li>
       * Receiving a call to {@link MenuItem.OnMenuItemClickListener#onMenuItemClick
       *  MenuItem.OnMenuItemClickListener.onMenuItemClick}.
       * </li>
       * <li>
       * Receiving a call to {@link android.app.Activity#onOptionsItemSelected(MenuItem)
       *  Activity.onOptionsItemSelected(MenuItem)}
       * </li>
       * <li>
       * Receiving a call to {@link android.app.Fragment#onOptionsItemSelected(MenuItem)
       *  Fragment.onOptionsItemSelected(MenuItem)}
       * </li>
       * <li>
       * Launching the {@link android.content.Intent} set via
       * {@link MenuItem#setIntent(android.content.Intent) MenuItem.setIntent(android.content.Intent)}
       * </li>
       * <li>
       * Invoking this method.
       * </li>
       * </ul>
       * </p>
       * <p>
       * The default implementation does not perform any action and returns false.
       * </p>
       */
      public boolean onPerformDefaultAction() {
          return false;
      }
  
      /**
       * Determines if this ActionProvider has a submenu associated with it.
       *
       * <p>Associated submenus will be shown when an action view is not. This
       * provider instance will receive a call to {@link #onPrepareSubMenu(SubMenu)}
       * after the call to {@link #onPerformDefaultAction()} and before a submenu is
       * displayed to the user.
       *
       * @return true if the item backed by this provider should have an associated submenu
       */
      public boolean hasSubMenu() {
          return false;
      }
  
      /**
       * Called to prepare an associated submenu for the menu item backed by this ActionProvider.
       *
       * <p>if {@link #hasSubMenu()} returns true, this method will be called when the
       * menu item is selected to prepare the submenu for presentation to the user. Apps
       * may use this to create or alter submenu content right before display.
       *
       * @param subMenu Submenu that will be displayed
       */
      public void onPrepareSubMenu(SubMenu subMenu) {
      }
  
      /**
       * Notify the system that the visibility of an action view's sub-UI such as
       * an anchored popup has changed. This will affect how other system
       * visibility notifications occur.
       *
       * @hide Pending future API approval
       */
      public void subUiVisibilityChanged(boolean isVisible) {
          if (mSubUiVisibilityListener != null) {
              mSubUiVisibilityListener.onSubUiVisibilityChanged(isVisible);
          }
      }
  
      /**
       * @hide Internal use only
       */
      public void setSubUiVisibilityListener(SubUiVisibilityListener listener) {
          mSubUiVisibilityListener = listener;
      }
  
      /**
       * @hide Internal use only
       */
      public interface SubUiVisibilityListener {
          public void onSubUiVisibilityChanged(boolean isVisible);
      }
  }
  