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 android.support.v7.internal.view.menu;
18
19import android.content.Context;
20import android.os.Parcelable;
21import android.view.ViewGroup;
22
23/**
24 * A MenuPresenter is responsible for building views for a Menu object. It takes over some
25 * responsibility from the old style monolithic MenuBuilder class.
26 *
27 * @hide
28 */
29public interface MenuPresenter {
30
31    /**
32     * Called by menu implementation to notify another component of open/close events.
33     *
34     * @hide
35     */
36    public interface Callback {
37        /**
38         * Called when a menu is closing.
39         * @param menu
40         * @param allMenusAreClosing
41         */
42        public void onCloseMenu(MenuBuilder menu, boolean allMenusAreClosing);
43
44        /**
45         * Called when a submenu opens. Useful for notifying the application
46         * of menu state so that it does not attempt to hide the action bar
47         * while a submenu is open or similar.
48         *
49         * @param subMenu Submenu currently being opened
50         * @return true if the Callback will handle presenting the submenu, false if
51         *         the presenter should attempt to do so.
52         */
53        public boolean onOpenSubMenu(MenuBuilder subMenu);
54    }
55
56    /**
57     * Initialize this presenter for the given context and menu.
58     * This method is called by MenuBuilder when a presenter is
59     * added. See {@link MenuBuilder#addMenuPresenter(MenuPresenter)}
60     *
61     * @param context Context for this presenter; used for view creation and resource management
62     * @param menu Menu to host
63     */
64    public void initForMenu(Context context, MenuBuilder menu);
65
66    /**
67     * Retrieve a MenuView to display the menu specified in
68     * {@link #initForMenu(Context, MenuBuilder)}.
69     *
70     * @param root Intended parent of the MenuView.
71     * @return A freshly created MenuView.
72     */
73    public MenuView getMenuView(ViewGroup root);
74
75    /**
76     * Update the menu UI in response to a change. Called by
77     * MenuBuilder during the normal course of operation.
78     *
79     * @param cleared true if the menu was entirely cleared
80     */
81    public void updateMenuView(boolean cleared);
82
83    /**
84     * Set a callback object that will be notified of menu events
85     * related to this specific presentation.
86     * @param cb Callback that will be notified of future events
87     */
88    public void setCallback(Callback cb);
89
90    /**
91     * Called by Menu implementations to indicate that a submenu item
92     * has been selected. An active Callback should be notified, and
93     * if applicable the presenter should present the submenu.
94     *
95     * @param subMenu SubMenu being opened
96     * @return true if the the event was handled, false otherwise.
97     */
98    public boolean onSubMenuSelected(SubMenuBuilder subMenu);
99
100    /**
101     * Called by Menu implementations to indicate that a menu or submenu is
102     * closing. Presenter implementations should close the representation
103     * of the menu indicated as necessary and notify a registered callback.
104     *
105     * @param menu Menu or submenu that is closing.
106     * @param allMenusAreClosing True if all associated menus are closing.
107     */
108    public void onCloseMenu(MenuBuilder menu, boolean allMenusAreClosing);
109
110    /**
111     * Called by Menu implementations to flag items that will be shown as actions.
112     * @return true if this presenter changed the action status of any items.
113     */
114    public boolean flagActionItems();
115
116    /**
117     * Called when a menu item with a collapsable action view should expand its action view.
118     *
119     * @param menu Menu containing the item to be expanded
120     * @param item Item to be expanded
121     * @return true if this presenter expanded the action view, false otherwise.
122     */
123    public boolean expandItemActionView(MenuBuilder menu, MenuItemImpl item);
124
125    /**
126     * Called when a menu item with a collapsable action view should collapse its action view.
127     *
128     * @param menu Menu containing the item to be collapsed
129     * @param item Item to be collapsed
130     * @return true if this presenter collapsed the action view, false otherwise.
131     */
132    public boolean collapseItemActionView(MenuBuilder menu, MenuItemImpl item);
133
134    /**
135     * Returns an ID for determining how to save/restore instance state.
136     * @return a valid ID value.
137     */
138    public int getId();
139
140    /**
141     * Returns a Parcelable describing the current state of the presenter.
142     * It will be passed to the {@link #onRestoreInstanceState(Parcelable)}
143     * method of the presenter sharing the same ID later.
144     * @return The saved instance state
145     */
146    public Parcelable onSaveInstanceState();
147
148    /**
149     * Supplies the previously saved instance state to be restored.
150     * @param state The previously saved instance state
151     */
152    public void onRestoreInstanceState(Parcelable state);
153}
154