API Overview API Index Package Overview Direct link to this page
JDK 1.6
  javax.sound.midi. MidiMessage View Javadoc
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171

/*
 * @(#)MidiMessage.java	1.30 05/11/17
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package javax.sound.midi;

/**
 * <code>MidiMessage</code> is the base class for MIDI messages.  They include
 * not only the standard MIDI messages that a synthesizer can respond to, but also
 * "meta-events" that can be used by sequencer programs.  There are meta-events
 * for such information as lyrics, copyrights, tempo indications, time and key
 * signatures, markers, etc.  For more information, see the Standard MIDI Files 1.0
 * specification, which is part of the Complete MIDI 1.0 Detailed Specification
 * published by the MIDI Manufacturer's Association
 * (<a href = http://www.midi.org>http://www.midi.org</a>).
 * <p>
 * The base <code>MidiMessage</code> class provides access to three types of
 * information about a MIDI message:
 * <ul>
 * <li>The messages's status byte</li>
 * <li>The total length of the message in bytes (the status byte plus any data bytes)</li>
 * <li>A byte array containing the complete message</li>
 * </ul>
 *
 * <code>MidiMessage</code> includes methods to get, but not set, these values.
 * Setting them is a subclass responsibility.
 * <p>
 * <a name="integersVsBytes"></a>
 * The MIDI standard expresses MIDI data in bytes.  However, because
 * Java<sup>TM</sup> uses signed bytes, the Java Sound API uses integers
 * instead of bytes when expressing MIDI data.  For example, the
 * {@link #getStatus()} method of
 * <code>MidiMessage</code> returns MIDI status bytes as integers.  If you are
 * processing MIDI data that originated outside Java Sound and now
 * is encoded as signed bytes, the bytes can
 * can be converted to integers using this conversion:
 * <center><code>int i = (int)(byte & 0xFF)</code></center>
 * <p>
 * If you simply need to pass a known MIDI byte value as a method parameter,
 * it can be expressed directly as an integer, using (for example) decimal or
 * hexidecimal notation.  For instance, to pass the "active sensing" status byte
 * as the first argument to ShortMessage's
 * {@link ShortMessage#setMessage(int) setMessage(int)}
 * method, you can express it as 254 or 0xFE.
 *
 * @see Track
 * @see Sequence
 * @see Receiver
 *
 * @version 1.30, 05/11/17
 * @author David Rivas
 * @author Kara Kytle
 */

public abstract class MidiMessage implements Cloneable {

    // Instance variables

    /**
     * The MIDI message data.  The first byte is the status
     * byte for the message; subsequent bytes up to the length
     * of the message are data bytes for this message.
     * @see #getLength
     */
    protected byte[] data;


    /**
     * The number of bytes in the MIDI message, including the
     * status byte and any data bytes.
     * @see #getLength
     */
    protected int length = 0;


    /**
     * Constructs a new <code>MidiMessage</code>.  This protected
     * constructor is called by concrete subclasses, which should
     * ensure that the data array specifies a complete, valid MIDI
     * message.
     *
     * @param data an array of bytes containing the complete message.
     * The message data may be changed using the <code>setMessage</code>
     * method.
     *
     * @see #setMessage
     */
    protected MidiMessage(byte[] data) {
	this.data = data;
	if (data != null) {
	    this.length = data.length;
	}
    }


    /**
     * Sets the data for the MIDI message.   This protected
     * method is called by concrete subclasses, which should
     * ensure that the data array specifies a complete, valid MIDI
     * message.
     */
    protected void setMessage(byte[] data, int length) throws InvalidMidiDataException {
	if (length < 0 || (length > 0 && length > data.length)) {
	    throw new IndexOutOfBoundsException("length out of bounds: "+length);
	}
	this.length = length;

	if (this.data == null || this.data.length < this.length) {
	    this.data = new byte[this.length];
	}
	System.arraycopy(data, 0, this.data, 0, length);
    }


    /**
     * Obtains the MIDI message data.  The first byte of the returned byte
     * array is the status byte of the message.  Any subsequent bytes up to
     * the length of the message are data bytes.  The byte array may have a
     * length which is greater than that of the actual message; the total
     * length of the message in bytes is reported by the <code>{@link #getLength}</code>
     * method.
     *
     * @return the byte array containing the complete <code>MidiMessage</code> data
     */
    public byte[] getMessage() {
	byte[] returnedArray = new byte[length];
	System.arraycopy(data, 0, returnedArray, 0, length);
	return returnedArray;
    }


    /**
     * Obtains the status byte for the MIDI message.  The status "byte" is
     * represented as an integer; see the
     * <a href="#integersVsBytes">discussion</a> in the
     * <code>MidiMessage</code> class description.
     *
     * @return the integer representation of this event's status byte
     */
    public int getStatus() {
	if (length > 0) {
	    return (data[0] & 0xFF);
	}
	return 0;
    }


    /**
     * Obtains the total length of the MIDI message in bytes.  A
     * MIDI message consists of one status byte and zero or more
     * data bytes.  The return value ranges from 1 for system real-time messages,
     * to 2 or 3 for channel messages, to any value for meta and system
     * exclusive messages.
     *
     * @return the length of the message in bytes
     */
    public int getLength() {
	return length;
    }


    /**
     * Creates a new object of the same class and with the same contents
     * as this object.
     * @return a clone of this instance.
     */
    public abstract Object clone();
}

Generated By: JavaOnTracks Doclet 0.1.4     ©Thibaut Colar