1 /**
2  * Copyright (C) 2016 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 package com.android.server.vr;
17 
18 import android.annotation.NonNull;
19 import android.content.BroadcastReceiver;
20 import android.content.ContentResolver;
21 import android.content.Context;
22 import android.content.Intent;
23 import android.database.ContentObserver;
24 import android.net.Uri;
25 import android.os.Handler;
26 import android.os.UserHandle;
27 import android.provider.Settings;
28 import android.util.ArraySet;
29 
30 import java.util.Objects;
31 import java.util.Set;
32 
33 /**
34  * Detects changes in a given setting.
35  *
36  * @hide
37  */
38 public class SettingsObserver {
39 
40     private final String mSecureSettingName;
41     private final BroadcastReceiver mSettingRestoreReceiver;
42     private final ContentObserver mContentObserver;
43     private final Set<SettingChangeListener> mSettingsListeners = new ArraySet<>();
44 
45     /**
46      * Implement this to receive callbacks when the setting tracked by this observer changes.
47      */
48     public interface SettingChangeListener {
49 
50         /**
51          * Called when the tracked setting has changed.
52          */
onSettingChanged()53         void onSettingChanged();
54 
55 
56         /**
57          * Called when the tracked setting has been restored for a particular user.
58          *
59          * @param prevValue the previous value of the setting.
60          * @param newValue the new value of the setting.
61          * @param userId the user ID for which this setting has been restored.
62          */
onSettingRestored(String prevValue, String newValue, int userId)63         void onSettingRestored(String prevValue, String newValue, int userId);
64     }
65 
SettingsObserver(@onNull final Context context, @NonNull final Handler handler, @NonNull final Uri settingUri, @NonNull final String secureSettingName)66     private SettingsObserver(@NonNull final Context context, @NonNull final Handler handler,
67             @NonNull final Uri settingUri, @NonNull final String secureSettingName) {
68 
69         mSecureSettingName = secureSettingName;
70         mSettingRestoreReceiver = new BroadcastReceiver() {
71             @Override
72             public void onReceive(Context context, Intent intent) {
73                 if (Intent.ACTION_SETTING_RESTORED.equals(intent.getAction())) {
74                     String element = intent.getStringExtra(Intent.EXTRA_SETTING_NAME);
75                     if (Objects.equals(element, secureSettingName)) {
76                         String prevValue = intent.getStringExtra(Intent.EXTRA_SETTING_PREVIOUS_VALUE);
77                         String newValue = intent.getStringExtra(Intent.EXTRA_SETTING_NEW_VALUE);
78                         sendSettingRestored(prevValue, newValue, getSendingUserId());
79                     }
80                 }
81             }
82         };
83 
84         mContentObserver = new ContentObserver(handler) {
85             @Override
86             public void onChange(boolean selfChange, Uri uri) {
87                 if (uri == null || settingUri.equals(uri)) {
88                     sendSettingChanged();
89                 }
90             }
91         };
92 
93         ContentResolver resolver = context.getContentResolver();
94         resolver.registerContentObserver(settingUri, false, mContentObserver,
95                 UserHandle.USER_ALL);
96     }
97 
98     /**
99      * Create a SettingsObserver instance.
100      *
101      * @param context the context to query for settings changes.
102      * @param handler the handler to use for a settings ContentObserver.
103      * @param settingName the setting to track.
104      * @return a SettingsObserver instance.
105      */
build(@onNull Context context, @NonNull Handler handler, @NonNull String settingName)106     public static SettingsObserver build(@NonNull Context context, @NonNull Handler handler,
107             @NonNull String settingName) {
108         Uri settingUri = Settings.Secure.getUriFor(settingName);
109 
110         return new SettingsObserver(context, handler, settingUri, settingName);
111     }
112 
113     /**
114      * Add a listener for setting changes.
115      *
116      * @param listener a {@link SettingChangeListener} instance.
117      */
addListener(@onNull SettingChangeListener listener)118     public void addListener(@NonNull SettingChangeListener listener) {
119         mSettingsListeners.add(listener);
120     }
121 
122     /**
123      * Remove a listener for setting changes.
124      *
125      * @param listener a {@link SettingChangeListener} instance.
126      */
removeListener(@onNull SettingChangeListener listener)127     public void removeListener(@NonNull SettingChangeListener listener) {
128         mSettingsListeners.remove(listener);
129 
130     }
131 
sendSettingChanged()132     private void sendSettingChanged() {
133         for (SettingChangeListener l : mSettingsListeners) {
134             l.onSettingChanged();
135         }
136     }
137 
sendSettingRestored(final String prevValue, final String newValue, final int userId)138     private void sendSettingRestored(final String prevValue, final String newValue, final int userId) {
139         for (SettingChangeListener l : mSettingsListeners) {
140             l.onSettingRestored(prevValue, newValue, userId);
141         }
142     }
143 
144 }
145