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| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
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| |
| 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 |
| * |
| * @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(); |
| } |