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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 
17 package com.android.internal.view.menu;
18 
19 import android.content.Context;
20 import android.os.Parcelable;
21 import android.view.Menu;
22 import 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  */
28 public 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          */
onCloseMenu(MenuBuilder menu, boolean allMenusAreClosing)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          */
onOpenSubMenu(MenuBuilder subMenu)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      */
initForMenu(Context context, MenuBuilder menu)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      */
getMenuView(ViewGroup root)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      */
updateMenuView(boolean cleared)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      */
setCallback(Callback cb)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      */
onSubMenuSelected(SubMenuBuilder subMenu)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      */
onCloseMenu(MenuBuilder menu, boolean allMenusAreClosing)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      */
flagActionItems()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      */
expandItemActionView(MenuBuilder menu, MenuItemImpl item)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      */
collapseItemActionView(MenuBuilder menu, MenuItemImpl item)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      */
getId()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      */
onSaveInstanceState()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      */
onRestoreInstanceState(Parcelable state)148     public void onRestoreInstanceState(Parcelable state);
149 }
150