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 // the list containing the events
68 private ArrayList<MidiEvent> eventsList = new ArrayList<>();
69
70 // use a hashset to detect duplicate events in add(MidiEvent)
71 private HashSet<MidiEvent> set = new HashSet<>();
72
73 private MidiEvent eotEvent;
74
75 /**
76 * Package-private constructor. Constructs a new, empty Track object, which
77 * initially contains one event, the meta-event End of Track.
78 */
79 Track() {
80 // start with the end of track event
81 MetaMessage eot = new ImmutableEndOfTrack();
82 eotEvent = new MidiEvent(eot, 0);
83 eventsList.add(eotEvent);
84 set.add(eotEvent);
85 }
86
87 /**
88 * Adds a new event to the track. However, if the event is already contained
89 * in the track, it is not added again. The list of events is kept in time
90 * order, meaning that this event inserted at the appropriate place in the
91 * list, not necessarily at the end.
92 *
93 * @param event the event to add
94 * @return {@code true} if the event did not already exist in the track and
95 * was added, otherwise {@code false}
96 */
97 public boolean add(MidiEvent event) {
98 if (event == null) {
99 return false;
100 }
101 synchronized(eventsList) {
102
103 if (!set.contains(event)) {
104 int eventsCount = eventsList.size();
105
106 // get the last event
107 MidiEvent lastEvent = null;
108 if (eventsCount > 0) {
109 lastEvent = eventsList.get(eventsCount - 1);
110 }
111 // sanity check that we have a correct end-of-track
112 if (lastEvent != eotEvent) {
113 // if there is no eot event, add our immutable instance again
114 if (lastEvent != null) {
115 // set eotEvent's tick to the last tick of the track
116 eotEvent.setTick(lastEvent.getTick());
117 } else {
118 // if the events list is empty, just set the tick to 0
119 eotEvent.setTick(0);
120 }
121 // we needn't check for a duplicate of eotEvent in "eventsList",
122 // since then it would appear in the set.
123 eventsList.add(eotEvent);
124 set.add(eotEvent);
125 eventsCount = eventsList.size();
126 }
127
128 // first see if we are trying to add
129 // and endoftrack event.
130 if (MidiUtils.isMetaEndOfTrack(event.getMessage())) {
131 // since end of track event is useful
132 // for delays at the end of a track, we want to keep
133 // the tick value requested here if it is greater
134 // than the one on the eot we are maintaining.
135 // Otherwise, we only want a single eot event, so ignore.
136 if (event.getTick() > eotEvent.getTick()) {
137 eotEvent.setTick(event.getTick());
138 }
139 return true;
140 }
141
142 // prevent duplicates
143 set.add(event);
144
145 // insert event such that events is sorted in increasing
146 // tick order
147 int i = eventsCount;
148 for ( ; i > 0; i--) {
149 if (event.getTick() >= (eventsList.get(i-1)).getTick()) {
150 break;
151 }
152 }
153 if (i == eventsCount) {
154 // we're adding an event after the
155 // tick value of our eot, so push the eot out.
156 // Always add at the end for better performance:
157 // this saves all the checks and arraycopy when inserting
158
159 // overwrite eot with new event
160 eventsList.set(eventsCount - 1, event);
161 // set new time of eot, if necessary
162 if (eotEvent.getTick() < event.getTick()) {
163 eotEvent.setTick(event.getTick());
164 }
165 // add eot again at the end
166 eventsList.add(eotEvent);
167 } else {
168 eventsList.add(i, event);
169 }
170 return true;
171 }
172 }
173
174 return false;
175 }
176
177 /**
178 * Removes the specified event from the track.
179 *
180 * @param event the event to remove
181 * @return {@code true} if the event existed in the track and was removed,
182 * otherwise {@code false}
183 */
184 public boolean remove(MidiEvent event) {
185
186 // this implementation allows removing the EOT event.
187 // pretty bad, but would probably be too risky to
188 // change behavior now, in case someone does tricks like:
189 //
190 // while (track.size() > 0) track.remove(track.get(track.size() - 1));
191
192 // also, would it make sense to adjust the EOT's time
193 // to the last event, if the last non-EOT event is removed?
194 // Or: document that the ticks() length will not be reduced
195 // by deleting events (unless the EOT event is removed)
196 synchronized(eventsList) {
197 if (set.remove(event)) {
198 int i = eventsList.indexOf(event);
199 if (i >= 0) {
200 eventsList.remove(i);
201 return true;
202 }
203 }
204 }
205 return false;
206 }
207
208 /**
209 * Obtains the event at the specified index.
210 *
211 * @param index the location of the desired event in the event vector
212 * @return the event at the specified index
213 * @throws ArrayIndexOutOfBoundsException if the specified index is negative
214 * or not less than the current size of this track
215 * @see #size
216 */
217 public MidiEvent get(int index) throws ArrayIndexOutOfBoundsException {
218 try {
219 synchronized(eventsList) {
220 return eventsList.get(index);
221 }
222 } catch (IndexOutOfBoundsException ioobe) {
223 throw new ArrayIndexOutOfBoundsException(ioobe.getMessage());
224 }
225 }
226
227 /**
228 * Obtains the number of events in this track.
229 *
230 * @return the size of the track's event vector
231 */
232 public int size() {
233 synchronized(eventsList) {
234 return eventsList.size();
235 }
236 }
237
238 /**
239 * Obtains the length of the track, expressed in MIDI ticks. (The duration
240 * of a tick in seconds is determined by the timing resolution of the
241 * {@code Sequence} containing this track, and also by the tempo of the
242 * music as set by the sequencer.)
243 *
244 * @return the duration, in ticks
245 * @see Sequence#Sequence(float, int)
246 * @see Sequencer#setTempoInBPM(float)
247 * @see Sequencer#getTickPosition()
248 */
249 public long ticks() {
250 long ret = 0;
251 synchronized (eventsList) {
252 if (eventsList.size() > 0) {
253 ret = (eventsList.get(eventsList.size() - 1)).getTick();
254 }
255 }
256 return ret;
257 }
258
259 private static class ImmutableEndOfTrack extends MetaMessage {
260 private ImmutableEndOfTrack() {
261 super(new byte[3]);
262 data[0] = (byte) META;
263 data[1] = MidiUtils.META_END_OF_TRACK_TYPE;
264 data[2] = 0;
265 }
266
267 public void setMessage(int type, byte[] data, int length) throws InvalidMidiDataException {
268 throw new InvalidMidiDataException("cannot modify end of track message");
269 }
270 }
271 }