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/* * @(#)Track.java 1.24 06/07/12 * * Copyright 2006 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 1.24, 06/07/12 * @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); eventsCount = eventsList.size(); } // 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"); } } }