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package javax.sound.midi;
import java.util.List;
/**
* {@code MidiDevice} is the base interface for all MIDI devices. Common devices
* include synthesizers, sequencers, MIDI input ports, and MIDI output ports.
* <p>
* A {@code MidiDevice} can be a transmitter or a receiver of MIDI events, or
* both. Therefore, it can provide {@link Transmitter} or {@link Receiver}
* instances (or both). Typically, MIDI IN ports provide transmitters, MIDI OUT
* ports and synthesizers provide receivers. A Sequencer typically provides
* transmitters for playback and receivers for recording.
* <p>
* A {@code MidiDevice} can be opened and closed explicitly as well as
* implicitly. Explicit opening is accomplished by calling {@link #open},
* explicit closing is done by calling {@link #close} on the {@code MidiDevice}
* instance. If an application opens a {@code MidiDevice} explicitly, it has to
* close it explicitly to free system resources and enable the application to
* exit cleanly. Implicit opening is done by calling
* {@link MidiSystem#getReceiver} and {@link MidiSystem#getTransmitter}. The
* {@code MidiDevice} used by {@code MidiSystem.getReceiver} and
* {@code MidiSystem.getTransmitter} is implementation-dependant unless the
* properties {@code javax.sound.midi.Receiver} and
* {@code javax.sound.midi.Transmitter} are used (see the description of
* properties to select default providers in {@link MidiSystem}). A
* {@code MidiDevice} that was opened implicitly, is closed implicitly by
* closing the {@code Receiver} or {@code Transmitter} that resulted in opening
* it. If more than one implicitly opening {@code Receiver} or
* {@code Transmitter} were obtained by the application, the device is closed
* after the last {@code Receiver} or {@code Transmitter} has been closed. On
* the other hand, calling {@code getReceiver} or {@code getTransmitter} on the
* device instance directly does not open the device implicitly. Closing these
* {@code Transmitter}s and {@code Receiver}s does not close the device
* implicitly. To use a device with {@code Receiver}s or {@code Transmitter}s
* obtained this way, the device has to be opened and closed explicitly.
* <p>
* If implicit and explicit opening and closing are mixed on the same
* {@code MidiDevice} instance, the following rules apply:
*
* <ul>
* <li>After an explicit open (either before or after implicit opens), the
* device will not be closed by implicit closing. The only way to close an
* explicitly opened device is an explicit close.</li>
* <li>An explicit close always closes the device, even if it also has been
* opened implicitly. A subsequent implicit close has no further effect.</li>
* </ul>
*
* To detect if a MidiDevice represents a hardware MIDI port, the following
* programming technique can be used:
*
* <pre>{@code
* MidiDevice device = ...;
* if ( ! (device instanceof Sequencer) && ! (device instanceof Synthesizer)) {
* // we're now sure that device represents a MIDI port
* // ...
* }
* }</pre>
*
* <p>
* A {@code MidiDevice} includes a {@link Info} object to provide manufacturer
* information and so on.
*
* @author Kara Kytle
* @author Florian Bomers
* @see Synthesizer
* @see Sequencer
* @see Receiver
* @see Transmitter
*/
public interface MidiDevice extends AutoCloseable {
/**
* Obtains information about the device, including its Java class and
* {@code Strings} containing its name, vendor, and description.
*
* @return device info
*/
Info getDeviceInfo();
/**
* Opens the device, indicating that it should now acquire any system
* resources it requires and become operational.
* <p>
* An application opening a device explicitly with this call has to close
* the device by calling {@link #close}. This is necessary to release system
* resources and allow applications to exit cleanly.
* <p>
* Note that some devices, once closed, cannot be reopened. Attempts to
* reopen such a device will always result in a MidiUnavailableException.
*
* @throws MidiUnavailableException thrown if the device cannot be opened
* due to resource restrictions
* @throws SecurityException thrown if the device cannot be opened due to
* security restrictions
* @see #close
* @see #isOpen
*/
void open() throws MidiUnavailableException;
/**
* Closes the device, indicating that the device should now release any
* system resources it is using.
* <p>
* All {@code Receiver} and {@code Transmitter} instances open from this
* device are closed. This includes instances retrieved via
* {@code MidiSystem}.
*
* @see #open
* @see #isOpen
*/
@Override
void close();
/**
* Reports whether the device is open.
*
* @return {@code true} if the device is open, otherwise {@code false}
* @see #open
* @see #close
*/
boolean isOpen();
/**
* Obtains the current time-stamp of the device, in microseconds. If a
* device supports time-stamps, it should start counting at 0 when the
* device is opened and continue incrementing its time-stamp in microseconds
* until the device is closed. If it does not support time-stamps, it should
* always return -1.
*
* @return the current time-stamp of the device in microseconds, or -1 if
* time-stamping is not supported by the device
*/
long getMicrosecondPosition();
/**
* Obtains the maximum number of MIDI IN connections available on this MIDI
* device for receiving MIDI data.
*
* @return maximum number of MIDI IN connections, or -1 if an unlimited
* number of connections is available
*/
int getMaxReceivers();
/**
* Obtains the maximum number of MIDI OUT connections available on this MIDI
* device for transmitting MIDI data.
*
* @return maximum number of MIDI OUT connections, or -1 if an unlimited
* number of connections is available
*/
int getMaxTransmitters();
/**
* Obtains a MIDI IN receiver through which the MIDI device may receive MIDI
* data. The returned receiver must be closed when the application has
* finished using it.
* <p>
* Usually the returned receiver implements the {@code MidiDeviceReceiver}
* interface.
* <p>
* Obtaining a {@code Receiver} with this method does not open the device.
* To be able to use the device, it has to be opened explicitly by calling
* {@link #open}. Also, closing the {@code Receiver} does not close the
* device. It has to be closed explicitly by calling {@link #close}.
*
* @return a receiver for the device
* @throws MidiUnavailableException thrown if a receiver is not available
* due to resource restrictions
* @see Receiver#close()
*/
Receiver getReceiver() throws MidiUnavailableException;
/**
* Returns all currently active, non-closed receivers connected with this
* MidiDevice. A receiver can be removed from the device by closing it.
* <p>
* Usually the returned receivers implement the {@code MidiDeviceReceiver}
* interface.
*
* @return an unmodifiable list of the open receivers
* @since 1.5
*/
List<Receiver> getReceivers();
/**
* Obtains a MIDI OUT connection from which the MIDI device will transmit
* MIDI data. The returned transmitter must be closed when the application
* has finished using it.
* <p>
* Usually the returned transmitter implements the
* {@code MidiDeviceTransmitter} interface.
* <p>
* Obtaining a {@code Transmitter} with this method does not open the
* device. To be able to use the device, it has to be opened explicitly by
* calling {@link #open}. Also, closing the {@code Transmitter} does not
* close the device. It has to be closed explicitly by calling
* {@link #close}.
*
* @return a MIDI OUT transmitter for the device
* @throws MidiUnavailableException thrown if a transmitter is not available
* due to resource restrictions
* @see Transmitter#close()
*/
Transmitter getTransmitter() throws MidiUnavailableException;
/**
* Returns all currently active, non-closed transmitters connected with this
* MidiDevice. A transmitter can be removed from the device by closing it.
* <p>
* Usually the returned transmitters implement the
* {@code MidiDeviceTransmitter} interface.
*
* @return an unmodifiable list of the open transmitters
* @since 1.5
*/
List<Transmitter> getTransmitters();
/**
* A {@code MidiDevice.Info} object contains assorted data about a
* {@link MidiDevice}, including its name, the company who created it, and
* descriptive text.
*
* @see MidiDevice#getDeviceInfo
*/
class Info {
/**
* The device's name.
*/
private final String name;
/**
* The name of the company who provides the device.
*/
private final String vendor;
/**
* A description of the device.
*/
private final String description;
/**
* Device version.
*/
private final String version;
/**
* Constructs a device info object.
*
* @param name the name of the device
* @param vendor the name of the company who provides the device
* @param description a description of the device
* @param version version information for the device
*/
protected Info(String name, String vendor, String description,
String version) {
this.name = name;
this.vendor = vendor;
this.description = description;
this.version = version;
}
/**
* Reports whether two objects are equal. Returns {@code true} if the
* objects are identical.
*
* @param obj the reference object with which to compare this object
* @return {@code true} if this object is the same as the {@code obj}
* argument; {@code false} otherwise
*/
@Override
public final boolean equals(Object obj) {
return super.equals(obj);
}
/**
* Finalizes the hashcode method.
*/
@Override
public final int hashCode() {
return super.hashCode();
}
/**
* Obtains the name of the device.
*
* @return a string containing the device's name
*/
public final String getName() {
return name;
}
/**
* Obtains the name of the company who supplies the device.
*
* @return device the vendor's name
*/
public final String getVendor() {
return vendor;
}
/**
* Obtains the description of the device.
*
* @return a description of the device
*/
public final String getDescription() {
return description;
}
/**
* Obtains the version of the device.
*
* @return textual version information for the device
*/
public final String getVersion() {
return version;
}
/**
* Provides a string representation of the device information.
*
* @return a description of the info object
*/
@Override
public final String toString() {
return name;
}
} // class Info
}