/*
* @(#)Track.java 1.22 03/12/19
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package javax.sound.midi;
import java.util.Vector;
import java.util.ArrayList;
import java.util.HashSet;
import com.sun.media.sound.MidiUtils;
/**
* A MIDI track is an independent stream of MIDI events (time-stamped MIDI
* data) that can be stored along with other tracks in a standard MIDI file.
* The MIDI specification allows only 16 channels of MIDI data, but tracks
* are a way to get around this limitation. A MIDI file can contain any number
* of tracks, each containing its own stream of up to 16 channels of MIDI data.
* <p>
* A <code>Track</code> occupies a middle level in the hierarchy of data played
* by a <code>{@link Sequencer}</code>: sequencers play sequences, which contain tracks,
* which contain MIDI events. A sequencer may provide controls that mute
* or solo individual tracks.
* <p>
* The timing information and resolution for a track is controlled by and stored
* in the sequence containing the track. A given <code>Track</code>
* is considered to belong to the particular <code>{@link Sequence}</code> that
* maintains its timing. For this reason, a new (empty) track is created by calling the
* <code>{@link Sequence#createTrack}</code> method, rather than by directly invoking a
* <code>Track</code> constructor.
* <p>
* The <code>Track</code> class provides methods to edit the track by adding
* or removing <code>MidiEvent</code> objects from it. These operations keep
* the event list in the correct time order. Methods are also
* included to obtain the track's size, in terms of either the number of events
* it contains or its duration in ticks.
*
* @see Sequencer#setTrackMute
* @see Sequencer#setTrackSolo
*
* @version 1.22, 03/12/19
* @author Kara Kytle
* @author Florian Bomers
*/
public class Track {
// TODO: use arrays for faster access
// the list containing the events
private ArrayList eventsList = new ArrayList();
// use a hashset to detect duplicate events in add(MidiEvent)
private HashSet set = new HashSet();
private MidiEvent eotEvent;
/**
* Package-private constructor. Constructs a new, empty Track object,
* which initially contains one event, the meta-event End of Track.
*/
Track() {
// start with the end of track event
MetaMessage eot = new ImmutableEndOfTrack();
eotEvent = new MidiEvent(eot, 0);
eventsList.add(eotEvent);
set.add(eotEvent);
}
/**
* Adds a new event to the track. However, if the event is already
* contained in the track, it is not added again. The list of events
* is kept in time order, meaning that this event inserted at the
* appropriate place in the list, not necessarily at the end.
*
* @param event the event to add
* @return <code>true</code> if the event did not already exist in the
* track and was added, otherwise <code>false</code>
*/
public boolean add(MidiEvent event) {
if (event == null) {
return false;
}
synchronized(eventsList) {
if (!set.contains(event)) {
int eventsCount = eventsList.size();
// get the last event
MidiEvent lastEvent = null;
if (eventsCount > 0) {
lastEvent = (MidiEvent) eventsList.get(eventsCount - 1);
}
// sanity check that we have a correct end-of-track
if (lastEvent != eotEvent) {
// if there is no eot event, add our immutable instance again
if (lastEvent != null) {
// set eotEvent's tick to the last tick of the track
eotEvent.setTick(lastEvent.getTick());
} else {
// if the events list is empty, just set the tick to 0
eotEvent.setTick(0);
}
// we needn't check for a duplicate of eotEvent in "eventsList",
// since then it would appear in the set.
eventsList.add(eotEvent);
set.add(eotEvent);
}
// first see if we are trying to add
// and endoftrack event.
if (MidiUtils.isMetaEndOfTrack(event.getMessage())) {
// since end of track event is useful
// for delays at the end of a track, we want to keep
// the tick value requested here if it is greater
// than the one on the eot we are maintaining.
// Otherwise, we only want a single eot event, so ignore.
if (event.getTick() > eotEvent.getTick()) {
eotEvent.setTick(event.getTick());
}
return true;
}
// prevent duplicates
set.add(event);
// insert event such that events is sorted in increasing
// tick order
int i = eventsCount;
for ( ; i > 0; i--) {
if (event.getTick() >= ((MidiEvent)eventsList.get(i-1)).getTick()) {
break;
}
}
if (i == eventsCount) {
// we're adding an event after the
// tick value of our eot, so push the eot out.
// Always add at the end for better performance:
// this saves all the checks and arraycopy when inserting
// overwrite eot with new event
eventsList.set(eventsCount - 1, event);
// set new time of eot, if necessary
if (eotEvent.getTick() < event.getTick()) {
eotEvent.setTick(event.getTick());
}
// add eot again at the end
eventsList.add(eotEvent);
} else {
eventsList.add(i, event);
}
return true;
}
}
return false;
}
/**
* Removes the specified event from the track.
* @param event the event to remove
* @return <code>true</code> if the event existed in the track and was removed,
* otherwise <code>false</code>
*/
public boolean remove(MidiEvent event) {
// this implementation allows removing the EOT event.
// pretty bad, but would probably be too risky to
// change behavior now, in case someone does tricks like:
//
// while (track.size() > 0) track.remove(track.get(track.size() - 1));
// also, would it make sense to adjust the EOT's time
// to the last event, if the last non-EOT event is removed?
// Or: document that the ticks() length will not be reduced
// by deleting events (unless the EOT event is removed)
synchronized(eventsList) {
if (set.remove(event)) {
int i = eventsList.indexOf(event);
if (i >= 0) {
eventsList.remove(i);
return true;
}
}
}
return false;
}
/**
* Obtains the event at the specified index.
* @param index the location of the desired event in the event vector
* @throws <code>ArrayIndexOutOfBoundsException</code> if the
* specified index is negative or not less than the current size of
* this track.
* @see #size
*/
public MidiEvent get(int index) throws ArrayIndexOutOfBoundsException {
try {
synchronized(eventsList) {
return (MidiEvent)eventsList.get(index);
}
} catch (IndexOutOfBoundsException ioobe) {
throw new ArrayIndexOutOfBoundsException(ioobe.getMessage());
}
}
/**
* Obtains the number of events in this track.
* @return the size of the track's event vector
*/
public int size() {
synchronized(eventsList) {
return eventsList.size();
}
}
/**
* Obtains the length of the track, expressed in MIDI ticks. (The
* duration of a tick in seconds is determined by the timing resolution
* of the <code>Sequence</code> containing this track, and also by
* the tempo of the music as set by the sequencer.)
* @return the duration, in ticks
* @see Sequence#Sequence(float, int)
* @see Sequencer#setTempoInBPM(float)
* @see Sequencer#getTickPosition()
*/
public long ticks() {
long ret = 0;
synchronized (eventsList) {
if (eventsList.size() > 0) {
ret = ((MidiEvent)eventsList.get(eventsList.size() - 1)).getTick();
}
}
return ret;
}
private static class ImmutableEndOfTrack extends MetaMessage {
private ImmutableEndOfTrack() {
super(new byte[3]);
data[0] = (byte) META;
data[1] = MidiUtils.META_END_OF_TRACK_TYPE;
data[2] = 0;
}
public void setMessage(int type, byte[] data, int length) throws InvalidMidiDataException {
throw new InvalidMidiDataException("cannot modify end of track message");
}
}
}
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