1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   5  * This code is free software; you can redistribute it and/or modify it
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   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.
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  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).
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  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-dependant 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.</li>
  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.</li>
  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 MidiUnavailableException.
 116      *
 117      * @throws MidiUnavailableException thrown if the device cannot be opened
 118      *         due to resource restrictions
 119      * @throws SecurityException thrown if the device cannot be opened due to
 120      *         security restrictions
 121      * @see #close
 122      * @see #isOpen
 123      */
 124     void open() throws MidiUnavailableException;
 125 
 126     /**
 127      * Closes the device, indicating that the device should now release any
 128      * system resources it is using.
 129      * <p>
 130      * All {@code Receiver} and {@code Transmitter} instances open from this
 131      * device are closed. This includes instances retrieved via
 132      * {@code MidiSystem}.
 133      *
 134      * @see #open
 135      * @see #isOpen
 136      */
 137     void close();
 138 
 139     /**
 140      * Reports whether the device is open.
 141      *
 142      * @return {@code true} if the device is open, otherwise {@code false}
 143      * @see #open
 144      * @see #close
 145      */
 146     boolean isOpen();
 147 
 148     /**
 149      * Obtains the current time-stamp of the device, in microseconds. If a
 150      * device supports time-stamps, it should start counting at 0 when the
 151      * device is opened and continue incrementing its time-stamp in microseconds
 152      * until the device is closed. If it does not support time-stamps, it should
 153      * always return -1.
 154      *
 155      * @return the current time-stamp of the device in microseconds, or -1 if
 156      *         time-stamping is not supported by the device
 157      */
 158     long getMicrosecondPosition();
 159 
 160     /**
 161      * Obtains the maximum number of MIDI IN connections available on this MIDI
 162      * device for receiving MIDI data.
 163      *
 164      * @return maximum number of MIDI IN connections, or -1 if an unlimited
 165      *         number of connections is available
 166      */
 167     int getMaxReceivers();
 168 
 169     /**
 170      * Obtains the maximum number of MIDI OUT connections available on this MIDI
 171      * device for transmitting MIDI data.
 172      *
 173      * @return maximum number of MIDI OUT connections, or -1 if an unlimited
 174      *         number of connections is available
 175      */
 176     int getMaxTransmitters();
 177 
 178     /**
 179      * Obtains a MIDI IN receiver through which the MIDI device may receive MIDI
 180      * data. The returned receiver must be closed when the application has
 181      * finished using it.
 182      * <p>
 183      * Usually the returned receiver implements the {@code MidiDeviceReceiver}
 184      * interface.
 185      * <p>
 186      * Obtaining a {@code Receiver} with this method does not open the device.
 187      * To be able to use the device, it has to be opened explicitly by calling
 188      * {@link #open}. Also, closing the {@code Receiver} does not close the
 189      * device. It has to be closed explicitly by calling {@link #close}.
 190      *
 191      * @return a receiver for the device
 192      * @throws MidiUnavailableException thrown if a receiver is not available
 193      *         due to resource restrictions
 194      * @see Receiver#close()
 195      */
 196     Receiver getReceiver() throws MidiUnavailableException;
 197 
 198     /**
 199      * Returns all currently active, non-closed receivers connected with this
 200      * MidiDevice. A receiver can be removed from the device by closing it.
 201      * <p>
 202      * Usually the returned receivers implement the {@code MidiDeviceReceiver}
 203      * interface.
 204      *
 205      * @return an unmodifiable list of the open receivers
 206      * @since 1.5
 207      */
 208     List<Receiver> getReceivers();
 209 
 210     /**
 211      * Obtains a MIDI OUT connection from which the MIDI device will transmit
 212      * MIDI data. The returned transmitter must be closed when the application
 213      * has finished using it.
 214      * <p>
 215      * Usually the returned transmitter implements the
 216      * {@code MidiDeviceTransmitter} interface.
 217      * <p>
 218      * Obtaining a {@code Transmitter} with this method does not open the
 219      * device. To be able to use the device, it has to be opened explicitly by
 220      * calling {@link #open}. Also, closing the {@code Transmitter} does not
 221      * close the device. It has to be closed explicitly by calling
 222      * {@link #close}.
 223      *
 224      * @return a MIDI OUT transmitter for the device
 225      * @throws MidiUnavailableException thrown if a transmitter is not available
 226      *         due to resource restrictions
 227      * @see Transmitter#close()
 228      */
 229     Transmitter getTransmitter() throws MidiUnavailableException;
 230 
 231     /**
 232      * Returns all currently active, non-closed transmitters connected with this
 233      * MidiDevice. A transmitter can be removed from the device by closing it.
 234      * <p>
 235      * Usually the returned transmitters implement the
 236      * {@code MidiDeviceTransmitter} interface.
 237      *
 238      * @return an unmodifiable list of the open transmitters
 239      * @since 1.5
 240      */
 241     List<Transmitter> getTransmitters();
 242 
 243     /**
 244      * A {@code MidiDevice.Info} object contains assorted data about a
 245      * {@link MidiDevice}, including its name, the company who created it, and
 246      * descriptive text.
 247      *
 248      * @see MidiDevice#getDeviceInfo
 249      */
 250     class Info {
 251 
 252         /**
 253          * The device's name.
 254          */
 255         private String name;
 256 
 257         /**
 258          * The name of the company who provides the device.
 259          */
 260         private String vendor;
 261 
 262         /**
 263          * A description of the device.
 264          */
 265         private String description;
 266 
 267         /**
 268          * Device version.
 269          */
 270         private String version;
 271 
 272         /**
 273          * Constructs a device info object.
 274          *
 275          * @param  name the name of the device
 276          * @param  vendor the name of the company who provides the device
 277          * @param  description a description of the device
 278          * @param  version version information for the device
 279          */
 280         protected Info(String name, String vendor, String description,
 281                        String version) {
 282 
 283             this.name = name;
 284             this.vendor = vendor;
 285             this.description = description;
 286             this.version = version;
 287         }
 288 
 289         /**
 290          * Reports whether two objects are equal. Returns {@code true} if the
 291          * objects are identical.
 292          *
 293          * @param  obj the reference object with which to compare this object
 294          * @return {@code true} if this object is the same as the {@code obj}
 295          *         argument; {@code false} otherwise
 296          */
 297         public final boolean equals(Object obj) {
 298             return super.equals(obj);
 299         }
 300 
 301         /**
 302          * Finalizes the hashcode method.
 303          */
 304         public final int hashCode() {
 305             return super.hashCode();
 306         }
 307 
 308         /**
 309          * Obtains the name of the device.
 310          *
 311          * @return a string containing the device's name
 312          */
 313         public final String getName() {
 314             return name;
 315         }
 316 
 317         /**
 318          * Obtains the name of the company who supplies the device.
 319          *
 320          * @return device the vendor's name
 321          */
 322         public final String getVendor() {
 323             return vendor;
 324         }
 325 
 326         /**
 327          * Obtains the description of the device.
 328          *
 329          * @return a description of the device
 330          */
 331         public final String getDescription() {
 332             return description;
 333         }
 334 
 335         /**
 336          * Obtains the version of the device.
 337          *
 338          * @return textual version information for the device.
 339          */
 340         public final String getVersion() {
 341             return version;
 342         }
 343 
 344         /**
 345          * Provides a string representation of the device information.
 346          *
 347          * @return a description of the info object
 348          */
 349         public final String toString() {
 350             return name;
 351         }
 352     } // class Info
 353 }