1 /*
2 * Copyright (c) 1999, 2017, 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
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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.List;
29
30 /**
31 * {@code MidiDevice} is the base interface for all MIDI devices. Common devices
32 * include synthesizers, sequencers, MIDI input ports, and MIDI output ports.
33 * <p>
34 * A {@code MidiDevice} can be a transmitter or a receiver of MIDI events, or
35 * both. Therefore, it can provide {@link Transmitter} or {@link Receiver}
36 * instances (or both). Typically, MIDI IN ports provide transmitters, MIDI OUT
37 * ports and synthesizers provide receivers. A Sequencer typically provides
38 * transmitters for playback and receivers for recording.
39 * <p>
40 * A {@code MidiDevice} can be opened and closed explicitly as well as
41 * implicitly. Explicit opening is accomplished by calling {@link #open},
42 * explicit closing is done by calling {@link #close} on the {@code MidiDevice}
43 * instance. If an application opens a {@code MidiDevice} explicitly, it has to
44 * close it explicitly to free system resources and enable the application to
45 * exit cleanly. Implicit opening is done by calling
46 * {@link MidiSystem#getReceiver} and {@link MidiSystem#getTransmitter}. The
47 * {@code MidiDevice} used by {@code MidiSystem.getReceiver} and
48 * {@code MidiSystem.getTransmitter} is implementation-dependent unless the
49 * properties {@code javax.sound.midi.Receiver} and
50 * {@code javax.sound.midi.Transmitter} are used (see the description of
51 * properties to select default providers in {@link MidiSystem}). A
52 * {@code MidiDevice} that was opened implicitly, is closed implicitly by
53 * closing the {@code Receiver} or {@code Transmitter} that resulted in opening
54 * it. If more than one implicitly opening {@code Receiver} or
55 * {@code Transmitter} were obtained by the application, the device is closed
56 * after the last {@code Receiver} or {@code Transmitter} has been closed. On
57 * the other hand, calling {@code getReceiver} or {@code getTransmitter} on the
58 * device instance directly does not open the device implicitly. Closing these
59 * {@code Transmitter}s and {@code Receiver}s does not close the device
60 * implicitly. To use a device with {@code Receiver}s or {@code Transmitter}s
61 * obtained this way, the device has to be opened and closed explicitly.
62 * <p>
63 * If implicit and explicit opening and closing are mixed on the same
64 * {@code MidiDevice} instance, the following rules apply:
65 *
66 * <ul>
67 * <li>After an explicit open (either before or after implicit opens), the
68 * device will not be closed by implicit closing. The only way to close an
69 * explicitly opened device is an explicit close.
70 * <li>An explicit close always closes the device, even if it also has been
71 * opened implicitly. A subsequent implicit close has no further effect.
72 * </ul>
73 *
74 * To detect if a MidiDevice represents a hardware MIDI port, the following
75 * programming technique can be used:
76 *
77 * <pre>{@code
78 * MidiDevice device = ...;
79 * if (!(device instanceof Sequencer) && !(device instanceof Synthesizer)) {
80 * // we're now sure that device represents a MIDI port
81 * // ...
82 * }
83 * }</pre>
84 *
85 * <p>
86 * A {@code MidiDevice} includes a {@link Info} object to provide manufacturer
87 * information and so on.
88 *
89 * @author Kara Kytle
90 * @author Florian Bomers
91 * @see Synthesizer
92 * @see Sequencer
93 * @see Receiver
94 * @see Transmitter
95 */
96 public interface MidiDevice extends AutoCloseable {
97
98 /**
99 * Obtains information about the device, including its Java class and
100 * {@code Strings} containing its name, vendor, and description.
101 *
102 * @return device info
103 */
104 Info getDeviceInfo();
105
106 /**
107 * Opens the device, indicating that it should now acquire any system
108 * resources it requires and become operational.
109 * <p>
110 * An application opening a device explicitly with this call has to close
111 * the device by calling {@link #close}. This is necessary to release system
112 * resources and allow applications to exit cleanly.
113 * <p>
114 * Note that some devices, once closed, cannot be reopened. Attempts to
115 * reopen such a device will always result in a
116 * {@code MidiUnavailableException}.
117 *
118 * @throws MidiUnavailableException thrown if the device cannot be opened
119 * due to resource restrictions
120 * @throws SecurityException thrown if the device cannot be opened due to
121 * security restrictions
122 * @see #close
123 * @see #isOpen
124 */
125 void open() throws MidiUnavailableException;
126
127 /**
128 * Closes the device, indicating that the device should now release any
129 * system resources it is using.
130 * <p>
131 * All {@code Receiver} and {@code Transmitter} instances open from this
132 * device are closed. This includes instances retrieved via
133 * {@code MidiSystem}.
134 *
135 * @see #open
136 * @see #isOpen
137 */
138 @Override
139 void close();
140
141 /**
142 * Reports whether the device is open.
143 *
144 * @return {@code true} if the device is open, otherwise {@code false}
145 * @see #open
146 * @see #close
147 */
148 boolean isOpen();
149
150 /**
151 * Obtains the current time-stamp of the device, in microseconds. If a
152 * device supports time-stamps, it should start counting at 0 when the
153 * device is opened and continue incrementing its time-stamp in microseconds
154 * until the device is closed. If it does not support time-stamps, it should
155 * always return -1.
156 *
157 * @return the current time-stamp of the device in microseconds, or -1 if
158 * time-stamping is not supported by the device
159 */
160 long getMicrosecondPosition();
161
162 /**
163 * Obtains the maximum number of MIDI IN connections available on this MIDI
164 * device for receiving MIDI data.
165 *
166 * @return maximum number of MIDI IN connections, or -1 if an unlimited
167 * number of connections is available
168 */
169 int getMaxReceivers();
170
171 /**
172 * Obtains the maximum number of MIDI OUT connections available on this MIDI
173 * device for transmitting MIDI data.
174 *
175 * @return maximum number of MIDI OUT connections, or -1 if an unlimited
176 * number of connections is available
177 */
178 int getMaxTransmitters();
179
180 /**
181 * Obtains a MIDI IN receiver through which the MIDI device may receive MIDI
182 * data. The returned receiver must be closed when the application has
183 * finished using it.
184 * <p>
185 * Usually the returned receiver implements the {@code MidiDeviceReceiver}
186 * interface.
187 * <p>
188 * Obtaining a {@code Receiver} with this method does not open the device.
189 * To be able to use the device, it has to be opened explicitly by calling
190 * {@link #open}. Also, closing the {@code Receiver} does not close the
191 * device. It has to be closed explicitly by calling {@link #close}.
192 *
193 * @return a receiver for the device
194 * @throws MidiUnavailableException thrown if a receiver is not available
195 * due to resource restrictions
196 * @see Receiver#close()
197 */
198 Receiver getReceiver() throws MidiUnavailableException;
199
200 /**
201 * Returns all currently active, non-closed receivers connected with this
202 * {@code MidiDevice}. A receiver can be removed from the device by closing
203 * it.
204 * <p>
205 * Usually the returned receivers implement the {@code MidiDeviceReceiver}
206 * interface.
207 *
208 * @return an unmodifiable list of the open receivers
209 * @since 1.5
210 */
211 List<Receiver> getReceivers();
212
213 /**
214 * Obtains a MIDI OUT connection from which the MIDI device will transmit
215 * MIDI data. The returned transmitter must be closed when the application
216 * has finished using it.
217 * <p>
218 * Usually the returned transmitter implements the
219 * {@code MidiDeviceTransmitter} interface.
220 * <p>
221 * Obtaining a {@code Transmitter} with this method does not open the
222 * device. To be able to use the device, it has to be opened explicitly by
223 * calling {@link #open}. Also, closing the {@code Transmitter} does not
224 * close the device. It has to be closed explicitly by calling
225 * {@link #close}.
226 *
227 * @return a MIDI OUT transmitter for the device
228 * @throws MidiUnavailableException thrown if a transmitter is not available
229 * due to resource restrictions
230 * @see Transmitter#close()
231 */
232 Transmitter getTransmitter() throws MidiUnavailableException;
233
234 /**
235 * Returns all currently active, non-closed transmitters connected with this
236 * {@code MidiDevice}. A transmitter can be removed from the device by
237 * closing it.
238 * <p>
239 * Usually the returned transmitters implement the
240 * {@code MidiDeviceTransmitter} interface.
241 *
242 * @return an unmodifiable list of the open transmitters
243 * @since 1.5
244 */
245 List<Transmitter> getTransmitters();
246
247 /**
248 * A {@code MidiDevice.Info} object contains assorted data about a
249 * {@link MidiDevice}, including its name, the company who created it, and
250 * descriptive text.
251 *
252 * @see MidiDevice#getDeviceInfo
253 */
254 class Info {
255
256 /**
257 * The device's name.
258 */
259 private final String name;
260
261 /**
262 * The name of the company who provides the device.
263 */
264 private final String vendor;
265
266 /**
267 * A description of the device.
268 */
269 private final String description;
270
271 /**
272 * Device version.
273 */
274 private final String version;
275
276 /**
277 * Constructs a device info object.
278 *
279 * @param name the name of the device
280 * @param vendor the name of the company who provides the device
281 * @param description a description of the device
282 * @param version version information for the device
283 */
284 protected Info(String name, String vendor, String description,
285 String version) {
286
287 this.name = name;
288 this.vendor = vendor;
289 this.description = description;
290 this.version = version;
291 }
292
293 /**
294 * Indicates whether the specified object is equal to this info object,
295 * returning {@code true} if the objects are the same.
296 *
297 * @param obj the reference object with which to compare
298 * @return {@code true} if the specified object is equal to this info
299 * object; {@code false} otherwise
300 */
301 @Override
302 public final boolean equals(Object obj) {
303 return super.equals(obj);
304 }
305
306 /**
307 * Returns a hash code value for this info object.
308 *
309 * @return a hash code value for this info object
310 */
311 @Override
312 public final int hashCode() {
313 return super.hashCode();
314 }
315
316 /**
317 * Obtains the name of the device.
318 *
319 * @return a string containing the device's name
320 */
321 public final String getName() {
322 return name;
323 }
324
325 /**
326 * Obtains the name of the company who supplies the device.
327 *
328 * @return device the vendor's name
329 */
330 public final String getVendor() {
331 return vendor;
332 }
333
334 /**
335 * Obtains the description of the device.
336 *
337 * @return a description of the device
338 */
339 public final String getDescription() {
340 return description;
341 }
342
343 /**
344 * Obtains the version of the device.
345 *
346 * @return textual version information for the device
347 */
348 public final String getVersion() {
349 return version;
350 }
351
352 /**
353 * Provides a string representation of the device information.
354 *
355 * @return a description of the info object
356 */
357 @Override
358 public final String toString() {
359 return name;
360 }
361 }
362 }