ViewMode.java revision 8ffe4320a17c3f4234f473e8f0ce083732064aa9 
1/*
2 * Copyright (C) 2012 Google Inc.
3 * Licensed to The Android Open Source Project.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 *      http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18package com.android.mail.ui;
19
20import com.google.common.collect.Lists;
21
22import android.content.Context;
23import android.os.Bundle;
24
25import com.android.mail.utils.Utils;
26
27import java.util.ArrayList;
28
29/**
30 * Represents the view mode for the tablet Gmail activity.
31 * Transitions between modes should be done through this central object, and UI components that are
32 * dependent on the mode should listen to changes on this object.
33 */
34public class ViewMode {
35    /**
36     * A listener for changes on a ViewMode.
37     */
38    public interface ModeChangeListener {
39        /**
40         * Handles a mode change.
41         */
42        void onViewModeChanged(ViewMode mode);
43    }
44
45    /**
46     * Mode when showing a single conversation.
47     */
48    public static final int CONVERSATION = 1;
49    /**
50     * Mode when showing a list of conversations
51     */
52    public static final int CONVERSATION_LIST = 2;
53    /**
54     * Mode when showing a list of folders.
55     */
56    public static final int FOLDER_LIST = 3;
57    /**
58     * Mode when showing results from user search.
59     */
60    public static final int SEARCH_RESULTS = 4;
61    /**
62     * Uncertain mode. The mode has not been initialized.
63     */
64    public static final int UNKNOWN = 0;
65
66    // Key used to save this {@link ViewMode}.
67    private static final String VIEW_MODE_KEY = "view-mode";
68    private final ArrayList<ModeChangeListener> mListeners = Lists.newArrayList();
69    private int mMode = UNKNOWN;
70    private boolean mTwoPane;
71
72    public ViewMode(Context context) {
73        mTwoPane = Utils.useTabletUI(context);
74    }
75
76    /**
77     *  Adds a listener from this view mode.
78     * Must happen in the UI thread.
79     */
80    public void addListener(ModeChangeListener listener) {
81        mListeners.add(listener);
82    }
83
84    /**
85     * Dispatches a change event for the mode.
86     * Always happens in the UI thread.
87     */
88    private void dispatchModeChange() {
89        ArrayList<ModeChangeListener> list = new ArrayList<ModeChangeListener>(mListeners);
90        for (ModeChangeListener listener : list) {
91            listener.onViewModeChanged(this);
92        }
93    }
94
95    /**
96     * @return The current mode.
97     */
98    public int getMode() {
99        return mMode;
100    }
101
102    public void handleRestore(Bundle inState) {
103        mMode = inState.getInt(VIEW_MODE_KEY);
104    }
105
106    public void handleSaveInstanceState(Bundle outState) {
107        outState.putInt(VIEW_MODE_KEY, mMode);
108    }
109
110    public boolean isConversationListMode() {
111        return mMode == CONVERSATION_LIST;
112    }
113
114    public boolean isConversationMode() {
115        return mMode == CONVERSATION;
116    }
117
118    public boolean isFolderListMode() {
119        return mMode == FOLDER_LIST;
120    }
121
122    /**
123     * @return Whether or not to display 2 pane.
124     */
125    public boolean isTwoPane() {
126        return mTwoPane;
127    }
128
129    /**
130     * Removes a listener from this view mode.
131     * Must happen in the UI thread.
132     */
133    public void removeListener(ModeChangeListener listener) {
134        mListeners.remove(listener);
135    }
136
137    /**
138     * Sets the internal mode.
139     * @return Whether or not a change occured.
140     */
141    private boolean setModeInternal(int mode) {
142        if (mMode == mode) {
143            return false;
144        }
145        mMode = mode;
146        dispatchModeChange();
147        return true;
148    }
149
150    /**
151     * Requests a transition of the mode to show the conversation list as the prominent view.
152     * @return Whether or not a change occured.
153     */
154    public boolean transitionToConversationListMode() {
155        return setModeInternal(CONVERSATION_LIST);
156    }
157
158    /**
159     * Requests a transition of the mode to show a conversation as the prominent view.
160     * @return Whether or not a change occured.
161     */
162    public boolean transitionToConversationMode() {
163        return setModeInternal(CONVERSATION);
164    }
165
166    /**
167     * Requests a transition of the mode to show the folder list as the prominent view.
168     * @return Whether or not a change occured.
169     */
170    public boolean transitionToFolderListMode() {
171        return setModeInternal(FOLDER_LIST);
172    }
173}
174