| /* |
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| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
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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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| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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| * accompanied this code). |
| * |
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| |
| package javax.sound.midi; |
| |
| /** |
| * {@code MidiMessage} 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} 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} includes methods to get, but not set, these values. |
| * Setting them is a subclass responsibility. |
| * <p> |
| * <a id="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} 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 be |
| * converted to integers using this conversion: |
| * <p style="text-align:center"> |
| * {@code int i = (int)(byte & 0xFF)} |
| * <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 |
| * hexadecimal 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. |
| * |
| * @author David Rivas |
| * @author Kara Kytle |
| * @see Track |
| * @see Sequence |
| * @see Receiver |
| */ |
| public abstract class MidiMessage implements Cloneable { |
| |
| /** |
| * 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}. 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} 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. |
| * |
| * @param data the data bytes in the MIDI message |
| * @param length the number of bytes in the data byte array |
| * @throws InvalidMidiDataException if the parameter values do not specify a |
| * valid MIDI meta 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 {@link #getLength} method. |
| * |
| * @return the byte array containing the complete {@code MidiMessage} 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} |
| * 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 |
| */ |
| @Override |
| public abstract Object clone(); |
| } |
