haiku/docs/user/midi2/midiproducer.dox

/*!
\class BMidiProducer MidiProducer.h
\ingroup midi2
\ingroup libmidi2
\brief Streams MIDI events to connected consumers

A producer is an object that generate a stream of MIDI events. Each producer 
has a list of BMidiConsumer objects to which it is connected, and may be asked 
to connect to or disconnect from a BMidiConsumer. A producer can spray its 
events to multiple consumers at the same time. 

A BMidiProducer either represents a local producer, i.e. a class extending from 
BMidiLocalProducer, or is a proxy for a remote object published by another app. 

*/

/*!
\fn status_t BMidiProducer::Connect(BMidiConsumer* cons)
\brief Connects a consumer to this producer

Establishes a connection between this producer and the specified consumer 
endpoint. From now on, any events that this producer sprays will be sent to 
that consumer. You may connect multiple consumers to a producer.

\return B_OK on success, or an error code when the connection could not be 
established. If the consumer is a proxy for a remote object and that object no 
longer exists, Connect() returns B_ERROR. It also returns B_ERROR if you try to 
connect the same producer and consumer more than once.

\sa Disconnect()
*/

/*!
\fn status_t BMidiProducer::Disconnect(BMidiConsumer* cons)
\brief Disconnects a consumer from this producer

Terminates the connection between this producer and the specified consumer 
endpoint. From now on, any events that this producer sprays no longer go to 
that consumer.

\return B_OK on success, or an error code if there was no connection to break

\sa Connect()
*/

/*!
\fn bool BMidiProducer::IsConnected(BMidiConsumer* cons) const
\brief Determines whether a consumer is connected to this producer
\sa Connect()
\sa Disconnect()
*/

/*!
\fn BList* BMidiProducer::Connections() const
\brief Returns a list with all connected consumers

Returns a BList with pointers to BMidiEndpoint objects for all consumers that 
are connected to this producer. You can examine the contents of the list as 
follows:

\code
BList* list = prod->Connections();
for (int32 t = 0; t < list->CountItems(); ++t)
{
    BMidiEndpoint* endp = (BMidiEndpoint*) list->ItemAt(t);
    ...do stuff...
    endp->Release();  // yes, here too!
}
delete list;
\endcode

Every time you call this function, a new BList is allocated. The caller (that 
is you) is responsible for freeing this list. The BMidiEndpoint objects in the 
list have their reference counts bumped, so you need to Release() them before 
you delete the list or they will go all leaky on you.

*/

/*!
\class BMidiLocalProducer MidiProducer.h
\ingroup midi2
\ingroup libmidi2
\brief A producer endpoint that is created by your own application

You create a BMidiLocalProducer if you want your application to send MIDI 
events. You use the various spray functions to send events to all connected 
consumers. If no consumers are connected to the producer, any calls to the 
spray functions are ignored.

Most spray functions accept a channel argument. Even though MIDI channels are 
really numbered 1 through 16, the spray functions work with channels 0 through 
15. You can also specify the performance time for the event using the time 
argument. Specify 0 (or any time in the past) to perform the event "now", i.e. 
as soon as possible. You can also schedule events to be performed in the 
future, by passing a time such as system_time() + 5000000, which means 5 
seconds from now.

Unlike BMidiLocalConsumer, which should be subclassed almost always, you hardly 
ever need to derive a class from BMidiLocalProducer. The only reason for 
subclassing is when you need to know when the producer gets connected or 
disconnected.

Also unlike consumers, local producers have no thread of control directly 
associated with them. If you want to send out the MIDI events from a different 
thread, you will have to create one yourself.

*/

/*!
\fn BMidiLocalProducer::BMidiLocalProducer(const char *name = NULL)
\brief Creates a new local producer endpoint

The new endpoint is not visible to other applications until you Register() it.

You can tell the constructor what the name of the new producer will be. If you 
pass NULL (or use the default argument), then the producer's name will be an 
empty string. It won't be NULL, since endpoint names cannot be NULL.

There is no guarantee that the endpoint will be successfully created. For 
example, the Midi Server may not be running. Therefore, you should always call 
IsValid() after creating a new endpoint to make sure that everything went okay. 
If not, Release() the object to reclaim memory and abort gracefully.

\code
BMidiLocalProducer* prod = new BMidiLocalProducer(...);
if (!prod->IsValid())
{
    prod->Release();
    ...exit gracefully...
}
\endcode

*/

/*!
\fn void BMidiLocalProducer::Connected(BMidiConsumer* cons)
\brief Invoked when a new consumer is connected to this producer

Although typical notifications (i.e. from BMidiRoster's "watching" facility) 
are only sent if it is some other app that is performing the operation, 
Connected() is also called if you are making the connection yourself.

If you override this hook, you don't have to call the default implementation, 
because that does nothing.

\param cons The newly connected consumer. The reference count of the consumer 
object is not increased, so you should not Release() it. However, if you want 
to keep track of the consumer beyond this function, you should first Acquire() 
it, and Release() it when you are done.

\sa Disconnected()
*/

/*!
\fn void BMidiLocalProducer::Disconnected(BMidiConsumer* cons)
\brief Invoked when a consumer is disconnected from this producer
\sa Connected()
*/

/*!
\fn void BMidiLocalProducer::SprayData(
    void* data, size_t length, bool atomic = false, bigtime_t time = 0) const
\brief Sends raw MIDI data downstream to all connected consumers

Typically you won't have to call SprayData(); the other spray functions will do 
just fine. If you do call it, remember that you retain ownership of the data 
and that you are responsible for freeing it at some point. (Even though data is 
not declared const, the function does not change it.)

With atomic set to false, you can send a MIDI message in segments (perhaps for 
a large sysex dump). However, when you do this, you are on your own. The Midi 
Kit only tags the data as being non-atomic, but offers no additional support. 
The default implementation of BMidiLocalConsumer completely ignores such 
events. To handle non-atomic MIDI data, you should override the 
BMidiLocalConsumer::Data() hook and process the MIDI event yourself. All of
BMidiLocalProducer's other spray functions always send atomic data.

\param data the MIDI event data
\param length byte size of the data buffer
\param atomic whether the data buffer contains a single complete MIDI event
\param time the required performance time of the event

\sa BMidiLocalConsumer::Data()
*/

/*!
\fn void BMidiLocalProducer::SprayNoteOff(
    uchar channel, uchar note, uchar velocity, bigtime_t time = 0) const
\brief Sends a Note Off event to all connected consumers
\sa BMidiLocalConsumer::NoteOff()
*/

/*!
\fn void BMidiLocalProducer::SprayNoteOn(
    uchar channel, uchar note, uchar velocity, bigtime_t time = 0) const
\brief Sends a Note On event to all connected consumers
\sa BMidiLocalConsumer::NoteOn()
*/

/*!
\fn void BMidiLocalProducer::SprayKeyPressure(
    uchar channel, uchar note, uchar pressure, bigtime_t time = 0) const
\brief Sends a Polyphonic Pressure (Aftertouch) event to all connected 
consumers
\sa BMidiLocalConsumer::KeyPressure()
*/

/*!
\fn void BMidiLocalProducer::SprayControlChange(
    uchar channel, uchar controlNumber, uchar controlValue,
    bigtime_t time = 0) const
\brief Sends a Controller Change event to all connected consumers

\sa Midi2Defs.h
\sa BMidiLocalConsumer::ControlChange()
*/

/*!
\fn void BMidiLocalProducer::SprayProgramChange(
    uchar channel, uchar programNumber, bigtime_t time = 0) const
\brief Sends a Program Change event to all connected consumers
\sa BMidiLocalConsumer::ProgramChange()
*/

/*!
\fn void BMidiLocalProducer::SprayChannelPressure(
    uchar channel, uchar pressure, bigtime_t time = 0) const
\brief Sends a Channel Pressure event to all connected consumers
\sa BMidiLocalConsumer::ChannelPressure()
*/

/*!
\fn void BMidiLocalProducer::SprayPitchBend(
    uchar channel, uchar lsb, uchar msb, bigtime_t time = 0) const
\brief Sends a Pitch Bend event to all connected consumers
\sa BMidiLocalConsumer::PitchBend()
*/

/*!
\fn void BMidiLocalProducer::SpraySystemExclusive(
    void* data, size_t length, bigtime_t time = 0) const
\brief Sends a System Exclusive event to all connected consumers

You retain ownership of the data and are responsible for freeing it. Even 
though data is not declared const, the function does not change it. Even though 
the amount of data may be quite large, this function always sends sysex 
messages as an atomic block of data.

\sa BMidiLocalConsumer::SystemExclusive()
*/

/*!
\fn void BMidiLocalProducer::SpraySystemCommon(
    uchar status, uchar data1, uchar data2, bigtime_t time = 0) const
\brief Sends a System Common event to the connected consumers

The status byte must be one of the following:

<TABLE BORDER="1">
<TR><TD>0xF1</TD><TD>B_MIDI_TIME_CODE</TD><TD>data1 only</TD></TR>
<TR><TD>0xF2</TD><TD>B_SONG_POSITION</TD><TD>data1 and data2</TD></TR>
<TR><TD>0xF3</TD><TD>B_SONG_SELECT</TD><TD>data1 only</TD></TR>
<TR><TD>0xF5</TD><TD>B_CABLE_MESSAGE</TD><TD>data1 only</TD></TR>
<TR><TD>0xF6</TD><TD>B_TUNE_REQUEST</TD><TD>no data</TD></TR>
<TR><TD>0xF7</TD><TD>B_SYS_EX_END</TD><TD>no data</TD></TR>
</TABLE>

\sa BMidiLocalConsumer::SystemCommon()
*/

/*!
\fn void BMidiLocalProducer::SpraySystemRealTime(
    uchar status, bigtime_t time = 0) const
\brief Sends a Real Time event to the connected consumers

The status byte must be one of the following:

<TABLE BORDER="1">
<TR><TD>0xF8</TD><TD>B_TIMING_CLOCK</TD></TR>
<TR><TD>0xFA</TD><TD>B_START</TD></TR>
<TR><TD>0xFB</TD><TD>B_CONTINUE</TD></TR>
<TR><TD>0xFC</TD><TD>B_STOP</TD></TR>
<TR><TD>0xFE</TD><TD>B_ACTIVE_SENSING</TD></TR>
<TR><TD>0xFF</TD><TD>B_SYSTEM_RESET</TD></TR>
</TABLE>

Because of their high priority, the MIDI specification allows real time 
messages to "interleave" with other MIDI messages. A large sysex dump, for 
example, may be interrupted by a real time event. The Midi Kit, however, 
doesn't care. If you (or another producer) have just sent a big system 
exclusive to a consumer, any following real time message will simply have to 
wait until the consumer has dealt with the sysex.

\sa BMidiLocalConsumer::SystemRealTime()
*/

/*!
\fn void BMidiLocalProducer::SprayTempoChange(
    int32 bpm, bigtime_t time = 0) const
\brief Sends a Tempo Change event to the connected consumers.

This kind of Tempo Change event is not really part of the MIDI spec, rather
it is an extension from the SMF (Standard MIDI File) format.

\sa BMidiLocalConsumer::TempoChange()
*/