haiku/docs/user/midi2/midiroster.dox

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/*!
\class BMidiRoster MidiRoster.h
\brief Interface to the system-wide Midi Roster
BMidiRoster allows you to find available MIDI consumer and producer objects.
You can locate these objects using the iterative NextEndpoint(),
NextProducer(), and NextConsumer() methods or by requesting notification
messages to be sent with StartWatching(). Notification messages may contain
object IDs which can be resolved using the FindEndpoint(), FindProducer(), and
FindConsumer() methods.
The constructor and destructor of BMidiRoster are private, which means that you
cannot create or delete your own BMidiRoster objects. Every application can
have only one instance of BMidiRoster, which is automatically created the very
first time you use a Midi Kit function.
You can call BMidiRoster's functions like this:
\code
producer = BMidiRoster::FindProducer(someID);
\endcode
Or using the slightly more annoying:
\code
BMidiRoster* roster = BMidiRoster::MidiRoster();
if (roster != NULL)
{
producer = roster->FindProducer(someID);
}
\endcode
*/
/*!
\fn BMidiEndpoint* BMidiRoster::NextEndpoint(int32* id)
\brief Returns the next endpoint from the roster
The "next endpoint" means: the endpoint with the ID that follows id. So if you
set id to 3, the first possible endpoint it returns is endpoint 4. No endpoint
can have ID 0, so passing 0 gives you the first endpoint. If you pass NULL
instead of an ID, NextEndpoint() always returns NULL. When the function
returns, it sets id to the ID of the endpoint that was found. If no more
endpoints exist, NextEndpoint() returns NULL and id is not changed.
NextEndpoint() does <I>not</I> return locally created endpoints, even if they
are Register()'ed.
Usage example:
\code
int32 id = 0;
BMidiEndpoint* endp;
while ((endp = BMidiRoster::NextEndpoint(&id)) != NULL)
{
...do something with endpoint ...
endp->Release(); // don't forget!
}
\endcode
Remember that NextEndpoint() bumps the endpoint's reference count, so you
should always \link BMidiEndpoint::Release() Release() \endlink it when you are
done.
*/
/*!
\fn BMidiProducer* BMidiRoster::NextProducer(int32* id)
\brief Returns the next producer from the roster
Like NextEndpoint(), but only returns producer endpoints.
\sa NextConsumer
\sa NextEndpoint
*/
/*!
\fn BMidiConsumer* BMidiRoster::NextConsumer(int32* id)
\brief Returns the next consumer from the roster
Like NextEndpoint(), but only returns consumer endpoints.
\sa NextProducer
\sa NextEndpoint
*/
/*!
\fn BMidiEndpoint* BMidiRoster::FindEndpoint(
int32 id, bool localOnly = false)
\brief Returns the endpoint with the specified ID
FindEndpoint() will always find <I>any</I> local endpoints created by this
application; they do not have to be published with Register() first. If
localOnly is false, FindEndpoint() also looks at remote endpoints, otherwise
only local endpoints will be resolved. Returns NULL if no such endpoint could
be found.
You should use a dynamic_cast to convert the BMidiEndpoint into a producer or
consumer:
\code
BMidiEndpoint* endp = ...;
BMidiProducer* prod = NULL;
BMidiConsumer* cons = NULL;
if (endp->IsProducer())
{
prod = dynamic_cast<BMidiProducer*>(endp);
}
else if (endp->IsConsumer())
{
cons = dynamic_cast<BMidiConsumer*>(endp);
}
\endcode
Remember that FindEndpoint() increments the endpoint's reference count, so you
should always \link BMidiEndpoint::Release() Release() \endlink an endpoint
when you are done with it:
\code
BMidiEndpoint* endp = BMidiRoster::FindEndpoint(someID);
if (endp != NULL)
{
...do stuff with the endpoint...
endp->Release();
}
\endcode
*/
/*!
\fn BMidiProducer* BMidiRoster::FindProducer(
int32 id, bool localOnly = false)
\brief Finds the producer with the specified ID
Like FindEndpoint(), but only looks for producer endpoints. Returns NULL if no
endpoint with that ID exists, or if that endpoint is not a producer.
\sa FindConsumer
\sa FindEndpoint
*/
/*!
\fn BMidiConsumer* BMidiRoster::FindConsumer(
int32 id, bool localOnly = false)
\brief Finds the consumer with the specified ID
Like FindEndpoint(), but only looks for consumer endpoints. Returns NULL if no
endpoint with that ID exists, or if that endpoint is not a consumer.
\sa FindProducer
\sa FindEndpoint
*/
/*!
\fn void BMidiRoster::StartWatching(const BMessenger* msngr)
\brief Start receiving notifications from the Midi Roster
When you start watching, BMidiRoster sends you notifications for all currently
<I>published</I> <I>remote</I> endpoints, and all the current connections
between them. (At this point, BMidiRoster does not let you know about
connections between unpublished endpoints, nor does it tell you anything about
your local endpoints, even though they may be published.)
Thereafter, you'll receive notifications any time something important happens
to an object. The application that performs these operations is itself not
notified. The assumption here is that you already know about these changes,
because you are the one that is performing them.
The notifications are BMessages with code B_MIDI_EVENT. You specify the
BMessenger that will be used to send these messages. Each message contains a
field called be:op that describes the type of notification.
The "registered" and "unregistered" notifications are sent when a remote
endpoint Register()'s or Unregister()'s, respectively. You don't receive these
notifications when you register or unregister your local endpoints, but the
other apps will.
<TABLE BORDER="1">
<TR><TD>be:op</TD><TD>int32</TD><TD>B_MIDI_REGISTERED</TD></TR>
<TR><TD>be:id</TD><TD>int32</TD><TD>ID of the endpoint</TD></TR>
<TR><TD>be:type</TD><TD>string</TD><TD>"producer" or "consumer"</TD></TR>
</TABLE>
<TABLE BORDER="1">
<TR><TD>be:op</TD><TD>int32</TD><TD>B_MIDI_UNREGISTERED</TD></TR>
<TR><TD>be:id</TD><TD>int32</TD><TD>ID of the endpoint</TD></TR>
<TR><TD>be:type</TD><TD>string</TD><TD>"producer" or "consumer"</TD></TR>
</TABLE>
The "connected" and "disconnected" notifications are sent when a consumer \link
BMidiProducer::Connect() Connect()\endlink's to a producer, or when they \link
BMidiProducer::Disconnect() Disconnect() \endlink. You will receive these
notifications when <I>any</I> two endpoints connect or disconnect, even if they
are not published. (The purpose of which is debatable.) You won't receive the
notifications if you are the one making the connection, even if both endpoints
are remote. You <I>will</I> be notified when another app connects one of your
published endpoints.
<TABLE BORDER="1">
<TR><TD>be:op</TD><TD>int32</TD><TD>B_MIDI_CONNECTED</TD></TR>
<TR><TD>be:producer</TD><TD>int32</TD><TD>ID of the connector</TD></TR>
<TR><TD>be:consumer</TD><TD>int32</TD><TD>ID of the connectee</TD></TR>
</TABLE>
<TABLE BORDER="1">
<TR><TD>be:op</TD><TD>int32</TD><TD>B_MIDI_DISCONNECTED</TD></TR>
<TR><TD>be:producer</TD><TD>int32</TD><TD>ID of the connector</TD></TR>
<TR><TD>be:consumer</TD><TD>int32</TD><TD>ID of the connectee</TD></TR>
</TABLE>
The following notifications are sent when an endpoint's attributes are changed.
You receive these notifications only if another application is changing one of
its published endpoints.
<TABLE BORDER="1">
<TR><TD>be:op</TD><TD>int32</TD><TD>B_MIDI_CHANGED_NAME</TD></TR>
<TR><TD>be:id</TD><TD>int32</TD><TD>ID of the endpoint</TD></TR>
<TR><TD>be:type</TD><TD>string</TD><TD>"producer" or "consumer"</TD></TR>
<TR><TD>be:name</TD><TD>string</TD><TD>the endpoint's new name</TD></TR>
</TABLE>
<TABLE BORDER="1">
<TR><TD>be:op</TD><TD>int32</TD><TD>B_MIDI_CHANGED_LATENCY</TD></TR>
<TR><TD>be:id</TD><TD>int32</TD><TD>ID of the endpoint</TD></TR>
<TR><TD>be:type</TD><TD>string</TD><TD>"producer" or "consumer"</TD></TR>
<TR><TD>be:latency</TD><TD>int64</TD><TD>the new latency (microseconds)</TD></TR>
</TABLE>
<TABLE BORDER="1">
<TR><TD>be:op</TD><TD>int32</TD><TD>B_MIDI_CHANGED_PROPERTIES</TD></TR>
<TR><TD>be:id</TD><TD>int32</TD><TD>ID of the endpoint</TD></TR>
<TR><TD>be:type</TD><TD>string</TD><TD>"producer" or "consumer"</TD></TR>
<TR><TD>be:properties</TD><TD>BMessage</TD><TD>the new properties</TD></TR>
</TABLE>
Typical usage example:
\code
void MyView::AttachedToWindow()
{
BMessenger msgr(this);
BMidiRoster::StartWatching(&msgr);
}
void MyView::MessageReceived(BMessage* msg)
{
switch (msg->what)
{
case B_MIDI_EVENT:
HandleMidiEvent(msg);
break;
default:
super::MessageReceived(msg);
break;
}
}
\endcode
\sa \ref bmidiop "The possible be:op codes (BMidiOp)"
*/
/*!
\fn void BMidiRoster::StopWatching()
\brief Stop receiving notifications from the Midi Roster
\sa StartWatching()
*/
/*!
\fn status_t BMidiRoster::Register(BMidiEndpoint* object)
\brief Publishes an endpoint to other applications
Calls BMidiEndpoint's \link BMidiEndpoint::Register() Register() \endlink
method to publish an endpoint, which makes it visible to other applications.
*/
/*!
\fn status_t BMidiRoster::Unregister(BMidiEndpoint* object)
\brief Hides an endpoint from other applications
Calls BMidiEndpoint's \link BMidiEndpoint::Unregister() Unregister() \endlink
method to hide a previously published endpoint from other applications.
*/
/*!
\fn BMidiRoster* BMidiRoster::MidiRoster()
\brief Returns a pointer to the only instance of BMidiRoster
There is no real reason use this function, since all BMidiRoster's public
function are static.
*/