Skip to content

Most visited

Recently visited

navigation
MidiSynth / src / com.example.android.common.midi /

MidiEventScheduler.java

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
 
17
package com.example.android.common.midi;
18
 
19
import android.media.midi.MidiReceiver;
20
 
21
import java.io.IOException;
22
 
23
/**
24
 * Add MIDI Events to an EventScheduler
25
 */
26
public class MidiEventScheduler extends EventScheduler {
27
    private static final String TAG = "MidiEventScheduler";
28
    // Maintain a pool of scheduled events to reduce memory allocation.
29
    // This pool increases performance by about 14%.
30
    private final static int POOL_EVENT_SIZE = 16;
31
    private MidiReceiver mReceiver = new SchedulingReceiver();
32
 
33
    private class SchedulingReceiver extends MidiReceiver
34
    {
35
        /**
36
         * Store these bytes in the EventScheduler to be delivered at the specified
37
         * time.
38
         */
39
        @Override
40
        public void onSend(byte[] msg, int offset, int count, long timestamp)
41
                throws IOException {
42
            MidiEvent event = createScheduledEvent(msg, offset, count, timestamp);
43
            if (event != null) {
44
                add(event);
45
            }
46
        }
47
    }
48
 
49
    public static class MidiEvent extends SchedulableEvent {
50
        public int count = 0;
51
        public byte[] data;
52
 
53
        private MidiEvent(int count) {
54
            super(0);
55
            data = new byte[count];
56
        }
57
 
58
        private MidiEvent(byte[] msg, int offset, int count, long timestamp) {
59
            super(timestamp);
60
            data = new byte[count];
61
            System.arraycopy(msg, offset, data, 0, count);
62
            this.count = count;
63
        }
64
 
65
        @Override
66
        public String toString() {
67
            String text = "Event: ";
68
            for (int i = 0; i < count; i++) {
69
                text += data[i] + ", ";
70
            }
71
            return text;
72
        }
73
    }
74
 
75
    /**
76
     * Create an event that contains the message.
77
     */
78
    private MidiEvent createScheduledEvent(byte[] msg, int offset, int count,
79
            long timestamp) {
80
        MidiEvent event;
81
        if (count > POOL_EVENT_SIZE) {
82
            event = new MidiEvent(msg, offset, count, timestamp);
83
        } else {
84
            event = (MidiEvent) removeEventfromPool();
85
            if (event == null) {
86
                event = new MidiEvent(POOL_EVENT_SIZE);
87
            }
88
            System.arraycopy(msg, offset, event.data, 0, count);
89
            event.count = count;
90
            event.setTimestamp(timestamp);
91
        }
92
        return event;
93
    }
94
 
95
    /**
96
     * Return events to a pool so they can be reused.
97
     *
98
     * @param event
99
     */
100
    @Override
101
    public void addEventToPool(SchedulableEvent event) {
102
        // Make sure the event is suitable for the pool.
103
        if (event instanceof MidiEvent) {
104
            MidiEvent midiEvent = (MidiEvent) event;
105
            if (midiEvent.data.length == POOL_EVENT_SIZE) {
106
                super.addEventToPool(event);
107
            }
108
        }
109
    }
110
 
111
    /**
112
     * This MidiReceiver will write date to the scheduling buffer.
113
     * @return the MidiReceiver
114
     */
115
    public MidiReceiver getReceiver() {
116
        return mReceiver;
117
    }
118
 
119
}
This site uses cookies to store your preferences for site-specific language and display options.

Get the latest Android developer news and tips that will help you find success on Google Play.

* Required Fields

Hooray!

Browse this site in ?

You requested a page in , but your language preference for this site is .

Would you like to change your language preference and browse this site in ? If you want to change your language preference later, use the language menu at the bottom of each page.

This class requires API level or higher

This doc is hidden because your selected API level for the documentation is . You can change the documentation API level with the selector above the left navigation.

For more information about specifying the API level your app requires, read Supporting Different Platform Versions.

Take a one-minute survey?
Help us improve Android tools and documentation.