1 /*
2 * Copyright (c) 1999, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package javax.sound.midi;
27
28 import java.util.ArrayList;
29 import java.util.HashSet;
30
31 import com.sun.media.sound.MidiUtils;
32
33 /**
34 * A MIDI track is an independent stream of MIDI events (time-stamped MIDI data)
35 * that can be stored along with other tracks in a standard MIDI file. The MIDI
36 * specification allows only 16 channels of MIDI data, but tracks are a way to
37 * get around this limitation. A MIDI file can contain any number of tracks,
38 * each containing its own stream of up to 16 channels of MIDI data.
39 * <p>
40 * A {@code Track} occupies a middle level in the hierarchy of data played by a
41 * {@link Sequencer}: sequencers play sequences, which contain tracks, which
42 * contain MIDI events. A sequencer may provide controls that mute or solo
43 * individual tracks.
44 * <p>
45 * The timing information and resolution for a track is controlled by and stored
46 * in the sequence containing the track. A given {@code Track} is considered to
47 * belong to the particular {@link Sequence} that maintains its timing. For this
48 * reason, a new (empty) track is created by calling the
49 * {@link Sequence#createTrack} method, rather than by directly invoking a
50 * {@code Track} constructor.
51 * <p>
52 * The {@code Track} class provides methods to edit the track by adding or
53 * removing {@code MidiEvent} objects from it. These operations keep the event
54 * list in the correct time order. Methods are also included to obtain the
55 * track's size, in terms of either the number of events it contains or its
56 * duration in ticks.
57 *
58 * @author Kara Kytle
59 * @author Florian Bomers
60 * @see Sequencer#setTrackMute
61 * @see Sequencer#setTrackSolo
62 */
63 public class Track {
64
65 // TODO: use arrays for faster access
66
67 /**
68 * The list containing the events.
69 */
70 private final ArrayList<MidiEvent> eventsList = new ArrayList<>();
71
72 /**
73 * Use a hashset to detect duplicate events in add(MidiEvent).
74 */
75 private final HashSet<MidiEvent> set = new HashSet<>();
76
77 private final MidiEvent eotEvent;
78
79 /**
80 * Package-private constructor. Constructs a new, empty Track object, which
81 * initially contains one event, the meta-event End of Track.
82 */
83 Track() {
84 // start with the end of track event
85 MetaMessage eot = new ImmutableEndOfTrack();
86 eotEvent = new MidiEvent(eot, 0);
87 eventsList.add(eotEvent);
88 set.add(eotEvent);
89 }
90
91 /**
92 * Adds a new event to the track. However, if the event is already contained
93 * in the track, it is not added again. The list of events is kept in time
94 * order, meaning that this event inserted at the appropriate place in the
95 * list, not necessarily at the end.
96 *
97 * @param event the event to add
98 * @return {@code true} if the event did not already exist in the track and
99 * was added, otherwise {@code false}
100 */
101 public boolean add(MidiEvent event) {
102 if (event == null) {
103 return false;
104 }
105 synchronized(eventsList) {
106
107 if (!set.contains(event)) {
108 int eventsCount = eventsList.size();
109
110 // get the last event
111 MidiEvent lastEvent = null;
112 if (eventsCount > 0) {
113 lastEvent = eventsList.get(eventsCount - 1);
114 }
115 // sanity check that we have a correct end-of-track
116 if (lastEvent != eotEvent) {
117 // if there is no eot event, add our immutable instance again
118 if (lastEvent != null) {
119 // set eotEvent's tick to the last tick of the track
120 eotEvent.setTick(lastEvent.getTick());
121 } else {
122 // if the events list is empty, just set the tick to 0
123 eotEvent.setTick(0);
124 }
125 // we needn't check for a duplicate of eotEvent in "eventsList",
126 // since then it would appear in the set.
127 eventsList.add(eotEvent);
128 set.add(eotEvent);
129 eventsCount = eventsList.size();
130 }
131
132 // first see if we are trying to add
133 // and endoftrack event.
134 if (MidiUtils.isMetaEndOfTrack(event.getMessage())) {
135 // since end of track event is useful
136 // for delays at the end of a track, we want to keep
137 // the tick value requested here if it is greater
138 // than the one on the eot we are maintaining.
139 // Otherwise, we only want a single eot event, so ignore.
140 if (event.getTick() > eotEvent.getTick()) {
141 eotEvent.setTick(event.getTick());
142 }
143 return true;
144 }
145
146 // prevent duplicates
147 set.add(event);
148
149 // insert event such that events is sorted in increasing
150 // tick order
151 int i = eventsCount;
152 for ( ; i > 0; i--) {
153 if (event.getTick() >= (eventsList.get(i-1)).getTick()) {
154 break;
155 }
156 }
157 if (i == eventsCount) {
158 // we're adding an event after the
159 // tick value of our eot, so push the eot out.
160 // Always add at the end for better performance:
161 // this saves all the checks and arraycopy when inserting
162
163 // overwrite eot with new event
164 eventsList.set(eventsCount - 1, event);
165 // set new time of eot, if necessary
166 if (eotEvent.getTick() < event.getTick()) {
167 eotEvent.setTick(event.getTick());
168 }
169 // add eot again at the end
170 eventsList.add(eotEvent);
171 } else {
172 eventsList.add(i, event);
173 }
174 return true;
175 }
176 }
177
178 return false;
179 }
180
181 /**
182 * Removes the specified event from the track.
183 *
184 * @param event the event to remove
185 * @return {@code true} if the event existed in the track and was removed,
186 * otherwise {@code false}
187 */
188 public boolean remove(MidiEvent event) {
189
190 // this implementation allows removing the EOT event.
191 // pretty bad, but would probably be too risky to
192 // change behavior now, in case someone does tricks like:
193 //
194 // while (track.size() > 0) track.remove(track.get(track.size() - 1));
195
196 // also, would it make sense to adjust the EOT's time
197 // to the last event, if the last non-EOT event is removed?
198 // Or: document that the ticks() length will not be reduced
199 // by deleting events (unless the EOT event is removed)
200 synchronized(eventsList) {
201 if (set.remove(event)) {
202 int i = eventsList.indexOf(event);
203 if (i >= 0) {
204 eventsList.remove(i);
205 return true;
206 }
207 }
208 }
209 return false;
210 }
211
212 /**
213 * Obtains the event at the specified index.
214 *
215 * @param index the location of the desired event in the event vector
216 * @return the event at the specified index
217 * @throws ArrayIndexOutOfBoundsException if the specified index is negative
218 * or not less than the current size of this track
219 * @see #size
220 */
221 public MidiEvent get(int index) throws ArrayIndexOutOfBoundsException {
222 try {
223 synchronized(eventsList) {
224 return eventsList.get(index);
225 }
226 } catch (IndexOutOfBoundsException ioobe) {
227 throw new ArrayIndexOutOfBoundsException(ioobe.getMessage());
228 }
229 }
230
231 /**
232 * Obtains the number of events in this track.
233 *
234 * @return the size of the track's event vector
235 */
236 public int size() {
237 synchronized(eventsList) {
238 return eventsList.size();
239 }
240 }
241
242 /**
243 * Obtains the length of the track, expressed in MIDI ticks. (The duration
244 * of a tick in seconds is determined by the timing resolution of the
245 * {@code Sequence} containing this track, and also by the tempo of the
246 * music as set by the sequencer.)
247 *
248 * @return the duration, in ticks
249 * @see Sequence#Sequence(float, int)
250 * @see Sequencer#setTempoInBPM(float)
251 * @see Sequencer#getTickPosition()
252 */
253 public long ticks() {
254 long ret = 0;
255 synchronized (eventsList) {
256 if (eventsList.size() > 0) {
257 ret = (eventsList.get(eventsList.size() - 1)).getTick();
258 }
259 }
260 return ret;
261 }
262
263 private static class ImmutableEndOfTrack extends MetaMessage {
264 private ImmutableEndOfTrack() {
265 super(new byte[3]);
266 data[0] = (byte) META;
267 data[1] = MidiUtils.META_END_OF_TRACK_TYPE;
268 data[2] = 0;
269 }
270
271 @Override
272 public void setMessage(int type, byte[] data, int length) throws InvalidMidiDataException {
273 throw new InvalidMidiDataException("cannot modify end of track message");
274 }
275 }
276 }