1/*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.internal.view.menu;
18
19import android.content.Context;
20import android.os.Parcelable;
21import android.view.Menu;
22import android.view.ViewGroup;
23
24/**
25 * A MenuPresenter is responsible for building views for a Menu object.
26 * It takes over some responsibility from the old style monolithic MenuBuilder class.
27 */
28public interface MenuPresenter {
29    /**
30     * Called by menu implementation to notify another component of open/close events.
31     */
32    public interface Callback {
33        /**
34         * Called when a menu is closing.
35         * @param menu
36         * @param allMenusAreClosing
37         */
38        public void onCloseMenu(MenuBuilder menu, boolean allMenusAreClosing);
39
40        /**
41         * Called when a submenu opens. Useful for notifying the application
42         * of menu state so that it does not attempt to hide the action bar
43         * while a submenu is open or similar.
44         *
45         * @param subMenu Submenu currently being opened
46         * @return true if the Callback will handle presenting the submenu, false if
47         *         the presenter should attempt to do so.
48         */
49        public boolean onOpenSubMenu(MenuBuilder subMenu);
50    }
51
52    /**
53     * Initialize this presenter for the given context and menu.
54     * This method is called by MenuBuilder when a presenter is
55     * added. See {@link MenuBuilder#addMenuPresenter(MenuPresenter)}
56     *
57     * @param context Context for this presenter; used for view creation and resource management
58     * @param menu Menu to host
59     */
60    public void initForMenu(Context context, MenuBuilder menu);
61
62    /**
63     * Retrieve a MenuView to display the menu specified in
64     * {@link #initForMenu(Context, Menu)}.
65     *
66     * @param root Intended parent of the MenuView.
67     * @return A freshly created MenuView.
68     */
69    public MenuView getMenuView(ViewGroup root);
70
71    /**
72     * Update the menu UI in response to a change. Called by
73     * MenuBuilder during the normal course of operation.
74     *
75     * @param cleared true if the menu was entirely cleared
76     */
77    public void updateMenuView(boolean cleared);
78
79    /**
80     * Set a callback object that will be notified of menu events
81     * related to this specific presentation.
82     * @param cb Callback that will be notified of future events
83     */
84    public void setCallback(Callback cb);
85
86    /**
87     * Called by Menu implementations to indicate that a submenu item
88     * has been selected. An active Callback should be notified, and
89     * if applicable the presenter should present the submenu.
90     *
91     * @param subMenu SubMenu being opened
92     * @return true if the the event was handled, false otherwise.
93     */
94    public boolean onSubMenuSelected(SubMenuBuilder subMenu);
95
96    /**
97     * Called by Menu implementations to indicate that a menu or submenu is
98     * closing. Presenter implementations should close the representation
99     * of the menu indicated as necessary and notify a registered callback.
100     *
101     * @param menu Menu or submenu that is closing.
102     * @param allMenusAreClosing True if all associated menus are closing.
103     */
104    public void onCloseMenu(MenuBuilder menu, boolean allMenusAreClosing);
105
106    /**
107     * Called by Menu implementations to flag items that will be shown as actions.
108     * @return true if this presenter changed the action status of any items.
109     */
110    public boolean flagActionItems();
111
112    /**
113     * Called when a menu item with a collapsable action view should expand its action view.
114     *
115     * @param menu Menu containing the item to be expanded
116     * @param item Item to be expanded
117     * @return true if this presenter expanded the action view, false otherwise.
118     */
119    public boolean expandItemActionView(MenuBuilder menu, MenuItemImpl item);
120
121    /**
122     * Called when a menu item with a collapsable action view should collapse its action view.
123     *
124     * @param menu Menu containing the item to be collapsed
125     * @param item Item to be collapsed
126     * @return true if this presenter collapsed the action view, false otherwise.
127     */
128    public boolean collapseItemActionView(MenuBuilder menu, MenuItemImpl item);
129
130    /**
131     * Returns an ID for determining how to save/restore instance state.
132     * @return a valid ID value.
133     */
134    public int getId();
135
136    /**
137     * Returns a Parcelable describing the current state of the presenter.
138     * It will be passed to the {@link #onRestoreInstanceState(Parcelable)}
139     * method of the presenter sharing the same ID later.
140     * @return The saved instance state
141     */
142    public Parcelable onSaveInstanceState();
143
144    /**
145     * Supplies the previously saved instance state to be restored.
146     * @param state The previously saved instance state
147     */
148    public void onRestoreInstanceState(Parcelable state);
149}
150