BluetoothMidiDevice.java revision 9490eae3aa6b20cbd3c1557fd3a7eb927e12907f 
1/*
2 * Copyright (C) 2015 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.bluetoothmidiservice;
18
19import android.bluetooth.BluetoothDevice;
20import android.bluetooth.BluetoothGatt;
21import android.bluetooth.BluetoothGattCallback;
22import android.bluetooth.BluetoothGattCharacteristic;
23import android.bluetooth.BluetoothGattDescriptor;
24import android.bluetooth.BluetoothGattService;
25import android.bluetooth.BluetoothProfile;
26import android.content.Context;
27import android.media.midi.MidiReceiver;
28import android.media.midi.MidiManager;
29import android.media.midi.MidiDeviceServer;
30import android.media.midi.MidiDeviceInfo;
31import android.os.Bundle;
32import android.os.IBinder;
33import android.util.Log;
34
35import com.android.internal.midi.MidiEventScheduler;
36import com.android.internal.midi.MidiEventScheduler.MidiEvent;
37
38import libcore.io.IoUtils;
39
40import java.io.IOException;
41import java.util.List;
42import java.util.UUID;
43
44/**
45 * Class used to implement a Bluetooth MIDI device.
46 */
47public final class BluetoothMidiDevice {
48
49    private static final String TAG = "BluetoothMidiDevice";
50    private static final boolean DEBUG = false;
51
52    private static final int MAX_PACKET_SIZE = 20;
53
54    //  Bluetooth MIDI Gatt service UUID
55    private static final UUID MIDI_SERVICE = UUID.fromString(
56            "03B80E5A-EDE8-4B33-A751-6CE34EC4C700");
57    // Bluetooth MIDI Gatt characteristic UUID
58    private static final UUID MIDI_CHARACTERISTIC = UUID.fromString(
59            "7772E5DB-3868-4112-A1A9-F2669D106BF3");
60    // Descriptor UUID for enabling characteristic changed notifications
61    private static final UUID CLIENT_CHARACTERISTIC_CONFIG = UUID.fromString(
62            "00002902-0000-1000-8000-00805f9b34fb");
63
64    private final BluetoothDevice mBluetoothDevice;
65    private final BluetoothMidiService mService;
66    private final MidiManager mMidiManager;
67    private MidiReceiver mOutputReceiver;
68    private final MidiEventScheduler mEventScheduler = new MidiEventScheduler();
69
70    private MidiDeviceServer mDeviceServer;
71    private BluetoothGatt mBluetoothGatt;
72
73    private BluetoothGattCharacteristic mCharacteristic;
74
75    // PacketReceiver for receiving formatted packets from our BluetoothPacketEncoder
76    private final PacketReceiver mPacketReceiver = new PacketReceiver();
77
78    private final BluetoothPacketEncoder mPacketEncoder
79            = new BluetoothPacketEncoder(mPacketReceiver, MAX_PACKET_SIZE);
80
81    private final BluetoothPacketDecoder mPacketDecoder
82            = new BluetoothPacketDecoder(MAX_PACKET_SIZE);
83
84    private final BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {
85        @Override
86        public void onConnectionStateChange(BluetoothGatt gatt, int status,
87                int newState) {
88            String intentAction;
89            if (newState == BluetoothProfile.STATE_CONNECTED) {
90                Log.i(TAG, "Connected to GATT server.");
91                Log.i(TAG, "Attempting to start service discovery:" +
92                        mBluetoothGatt.discoverServices());
93            } else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
94                Log.i(TAG, "Disconnected from GATT server.");
95                close();
96            }
97        }
98
99        @Override
100        public void onServicesDiscovered(BluetoothGatt gatt, int status) {
101            if (status == BluetoothGatt.GATT_SUCCESS) {
102                List<BluetoothGattService> services = mBluetoothGatt.getServices();
103                for (BluetoothGattService service : services) {
104                    if (MIDI_SERVICE.equals(service.getUuid())) {
105                        Log.d(TAG, "found MIDI_SERVICE");
106                        List<BluetoothGattCharacteristic> characteristics
107                            = service.getCharacteristics();
108                        for (BluetoothGattCharacteristic characteristic : characteristics) {
109                            if (MIDI_CHARACTERISTIC.equals(characteristic.getUuid())) {
110                                Log.d(TAG, "found MIDI_CHARACTERISTIC");
111                                mCharacteristic = characteristic;
112
113                                // Specification says to read the characteristic first and then
114                                // switch to receiving notifications
115                                mBluetoothGatt.readCharacteristic(characteristic);
116                                break;
117                            }
118                        }
119                        break;
120                    }
121                }
122            } else {
123                Log.e(TAG, "onServicesDiscovered received: " + status);
124                close();
125            }
126        }
127
128        @Override
129        public void onCharacteristicRead(BluetoothGatt gatt,
130                BluetoothGattCharacteristic characteristic,
131                int status) {
132            Log.d(TAG, "onCharacteristicRead " + status);
133
134            // switch to receiving notifications after initial characteristic read
135            mBluetoothGatt.setCharacteristicNotification(characteristic, true);
136
137            BluetoothGattDescriptor descriptor = characteristic.getDescriptor(
138                    CLIENT_CHARACTERISTIC_CONFIG);
139            if (descriptor != null) {
140                descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
141                mBluetoothGatt.writeDescriptor(descriptor);
142            } else {
143                Log.e(TAG, "No CLIENT_CHARACTERISTIC_CONFIG for device " + mBluetoothDevice);
144            }
145        }
146
147        @Override
148        public void onCharacteristicWrite(BluetoothGatt gatt,
149                BluetoothGattCharacteristic characteristic,
150                int status) {
151            Log.d(TAG, "onCharacteristicWrite " + status);
152            mPacketEncoder.writeComplete();
153        }
154
155        @Override
156        public void onCharacteristicChanged(BluetoothGatt gatt,
157                                            BluetoothGattCharacteristic characteristic) {
158            if (DEBUG) {
159                logByteArray("Received ", characteristic.getValue(), 0,
160                        characteristic.getValue().length);
161            }
162            mPacketDecoder.decodePacket(characteristic.getValue(), mOutputReceiver);
163        }
164    };
165
166    // This receives MIDI data that has already been passed through our MidiEventScheduler
167    // and has been normalized by our MidiFramer.
168
169    private class PacketReceiver implements PacketEncoder.PacketReceiver {
170        // buffers of every possible packet size
171        private final byte[][] mWriteBuffers;
172
173        public PacketReceiver() {
174            // Create buffers of every possible packet size
175            mWriteBuffers = new byte[MAX_PACKET_SIZE + 1][];
176            for (int i = 0; i <= MAX_PACKET_SIZE; i++) {
177                mWriteBuffers[i] = new byte[i];
178            }
179        }
180
181        @Override
182        public void writePacket(byte[] buffer, int count) {
183            if (mCharacteristic == null) {
184                Log.w(TAG, "not ready to send packet yet");
185                return;
186            }
187            byte[] writeBuffer = mWriteBuffers[count];
188            System.arraycopy(buffer, 0, writeBuffer, 0, count);
189            mCharacteristic.setValue(writeBuffer);
190            if (DEBUG) {
191                logByteArray("Sent ", mCharacteristic.getValue(), 0,
192                       mCharacteristic.getValue().length);
193            }
194            mBluetoothGatt.writeCharacteristic(mCharacteristic);
195        }
196    }
197
198    public BluetoothMidiDevice(Context context, BluetoothDevice device,
199            BluetoothMidiService service) {
200        mBluetoothDevice = device;
201        mService = service;
202
203        mBluetoothGatt = mBluetoothDevice.connectGatt(context, false, mGattCallback);
204
205        mMidiManager = (MidiManager)context.getSystemService(Context.MIDI_SERVICE);
206
207        Bundle properties = new Bundle();
208        properties.putString(MidiDeviceInfo.PROPERTY_NAME, mBluetoothGatt.getDevice().getName());
209        properties.putParcelable(MidiDeviceInfo.PROPERTY_BLUETOOTH_DEVICE,
210                mBluetoothGatt.getDevice());
211
212        MidiReceiver[] inputPortReceivers = new MidiReceiver[1];
213        inputPortReceivers[0] = mEventScheduler.getReceiver();
214
215        mDeviceServer = mMidiManager.createDeviceServer(inputPortReceivers, 1,
216                null, null, properties, MidiDeviceInfo.TYPE_BLUETOOTH, null);
217
218        mOutputReceiver = mDeviceServer.getOutputPortReceivers()[0];
219
220        // This thread waits for outgoing messages from our MidiEventScheduler
221        // And forwards them to our MidiFramer to be prepared to send via Bluetooth.
222        new Thread("BluetoothMidiDevice " + mBluetoothDevice) {
223            @Override
224            public void run() {
225                while (true) {
226                    MidiEvent event;
227                    try {
228                        event = (MidiEvent)mEventScheduler.waitNextEvent();
229                    } catch (InterruptedException e) {
230                        // try again
231                        continue;
232                    }
233                    if (event == null) {
234                        break;
235                    }
236                    try {
237                        mPacketEncoder.sendWithTimestamp(event.data, 0, event.count,
238                                event.getTimestamp());
239                    } catch (IOException e) {
240                        Log.e(TAG, "mPacketAccumulator.sendWithTimestamp failed", e);
241                    }
242                    mEventScheduler.addEventToPool(event);
243                }
244                Log.d(TAG, "BluetoothMidiDevice thread exit");
245            }
246        }.start();
247    }
248
249    private void close() {
250        synchronized (mBluetoothDevice) {
251        mEventScheduler.close();
252            if (mDeviceServer != null) {
253                IoUtils.closeQuietly(mDeviceServer);
254                mDeviceServer = null;
255                mService.deviceClosed(mBluetoothDevice);
256            }
257            if (mBluetoothGatt != null) {
258                mBluetoothGatt.close();
259                mBluetoothGatt = null;
260            }
261        }
262    }
263
264    public IBinder getBinder() {
265        return mDeviceServer.asBinder();
266    }
267
268    private static void logByteArray(String prefix, byte[] value, int offset, int count) {
269        StringBuilder builder = new StringBuilder(prefix);
270        for (int i = offset; i < count; i++) {
271            builder.append(String.format("0x%02X", value[i]));
272            if (i != value.length - 1) {
273                builder.append(", ");
274            }
275        }
276        Log.d(TAG, builder.toString());
277    }
278}
279