1/*
2 * Copyright 2014, 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.server.telecom;
18
19import android.content.Context;
20import android.media.AudioManager;
21import android.media.ToneGenerator;
22import android.os.Handler;
23import android.os.HandlerThread;
24import android.os.Message;
25import android.provider.Settings;
26
27import com.android.internal.util.Preconditions;
28
29// TODO: Needed for move to system service: import com.android.internal.R;
30
31/**
32 * Plays DTMF tones locally for the caller to hear. In order to reduce (1) the amount of times we
33 * check the "play local tones" setting and (2) the length of time we keep the tone generator, this
34 * class employs a concept of a call "session" that starts and stops when the foreground call
35 * changes.
36 */
37public class DtmfLocalTonePlayer {
38    /** Generator used to actually play the tone. */
39    private ToneGenerator mToneGenerator;
40
41    /** The current call associated with an existing dtmf session. */
42    private Call mCall;
43
44    /**
45     * Message codes to be used for creating and deleting ToneGenerator object in the tonegenerator
46     * thread.
47     */
48    private static final int EVENT_CREATE_OBJECT = 1;
49    private static final int EVENT_DELETE_OBJECT = 2;
50
51    /** Handler running on the tonegenerator thread. */
52    private Handler mHandler;
53
54    public DtmfLocalTonePlayer() { }
55
56    public void onForegroundCallChanged(Call oldForegroundCall, Call newForegroundCall) {
57        endDtmfSession(oldForegroundCall);
58        startDtmfSession(newForegroundCall);
59    }
60
61    /**
62     * Starts playing the dtmf tone specified by c.
63     *
64     * @param call The associated call.
65     * @param c The digit to play.
66     */
67    void playTone(Call call, char c) {
68        // Do nothing if it is not the right call.
69        if (mCall != call) {
70            return;
71        }
72        synchronized(this) {
73            if (mToneGenerator == null) {
74                Log.d(this, "playTone: mToneGenerator == null, %c.", c);
75            } else {
76                Log.d(this, "starting local tone: %c.", c);
77                int tone = getMappedTone(c);
78                if (tone != ToneGenerator.TONE_UNKNOWN) {
79                    mToneGenerator.startTone(tone, -1 /* toneDuration */);
80                }
81            }
82        }
83    }
84
85    /**
86     * Stops any currently playing dtmf tone.
87     *
88     * @param call The associated call.
89     */
90    void stopTone(Call call) {
91        // Do nothing if it's not the right call.
92        if (mCall != call) {
93            return;
94        }
95        synchronized(this) {
96            if (mToneGenerator == null) {
97                Log.d(this, "stopTone: mToneGenerator == null.");
98            } else {
99                Log.d(this, "stopping local tone.");
100                mToneGenerator.stopTone();
101            }
102        }
103    }
104
105    /**
106     * Runs initialization requires to play local tones during a call.
107     *
108     * @param call The call associated with this dtmf session.
109     */
110    private void startDtmfSession(Call call) {
111        if (call == null) {
112            return;
113        }
114        final Context context = call.getContext();
115        final boolean areLocalTonesEnabled;
116        if (context.getResources().getBoolean(R.bool.allow_local_dtmf_tones)) {
117            areLocalTonesEnabled = Settings.System.getInt(
118                    context.getContentResolver(), Settings.System.DTMF_TONE_WHEN_DIALING, 1) == 1;
119        } else {
120            areLocalTonesEnabled = false;
121        }
122
123        mCall = call;
124
125        if (areLocalTonesEnabled) {
126            Log.d(this, "Posting create.");
127            postMessage(EVENT_CREATE_OBJECT);
128        }
129    }
130
131    /**
132     * Releases resources needed for playing local dtmf tones.
133     *
134     * @param call The call associated with the session to end.
135     */
136    private void endDtmfSession(Call call) {
137        if (call != null && mCall == call) {
138            // Do a stopTone() in case the sessions ends before we are told to stop the tone.
139            stopTone(call);
140
141            mCall = null;
142            Log.d(this, "Posting delete.");
143            postMessage(EVENT_DELETE_OBJECT);
144        }
145    }
146
147    /**
148     * Posts a message to the tonegenerator-thread handler. Creates the handler if the handler
149     * has not been instantiated.
150     *
151     * @param messageCode The message to post.
152     */
153    private void postMessage(int messageCode) {
154        synchronized(this) {
155            if (mHandler == null) {
156                mHandler = getNewHandler();
157            }
158
159            if (mHandler == null) {
160                Log.d(this, "Message %d skipped because there is no handler.", messageCode);
161            } else {
162                mHandler.obtainMessage(messageCode, null).sendToTarget();
163            }
164        }
165    }
166
167    /**
168     * Creates a new tonegenerator Handler running in its own thread.
169     */
170    private Handler getNewHandler() {
171        Preconditions.checkState(mHandler == null);
172
173        HandlerThread thread = new HandlerThread("tonegenerator-dtmf");
174        thread.start();
175
176        return new Handler(thread.getLooper()) {
177            @Override
178            public void handleMessage(Message msg) {
179                switch(msg.what) {
180                    case EVENT_CREATE_OBJECT:
181                        synchronized(DtmfLocalTonePlayer.this) {
182                            if (mToneGenerator == null) {
183                                try {
184                                    mToneGenerator = new ToneGenerator(
185                                            AudioManager.STREAM_DTMF, 80);
186                                } catch (RuntimeException e) {
187                                    Log.e(this, e, "Error creating local tone generator.");
188                                    mToneGenerator = null;
189                                }
190                            }
191                        }
192                        break;
193                    case EVENT_DELETE_OBJECT:
194                        synchronized(DtmfLocalTonePlayer.this) {
195                            if (mToneGenerator != null) {
196                                mToneGenerator.release();
197                                mToneGenerator = null;
198                            }
199                            // Delete the handler after the tone generator object is deleted by
200                            // the tonegenerator thread.
201                            if (mHandler != null && !mHandler.hasMessages(EVENT_CREATE_OBJECT)) {
202                                // Stop the handler only if there are no pending CREATE messages.
203                                mHandler.removeMessages(EVENT_DELETE_OBJECT);
204                                mHandler.getLooper().quitSafely();
205                                mHandler = null;
206                            }
207                        }
208                        break;
209                }
210            }
211        };
212    }
213
214    private static int getMappedTone(char digit) {
215        if (digit >= '0' && digit <= '9') {
216            return ToneGenerator.TONE_DTMF_0 + digit - '0';
217        } else if (digit == '#') {
218            return ToneGenerator.TONE_DTMF_P;
219        } else if (digit == '*') {
220            return ToneGenerator.TONE_DTMF_S;
221        }
222        return ToneGenerator.TONE_UNKNOWN;
223    }
224}
225