Bonobo API Reference Manual | |||
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#define BONOBO_LISTENER_TYPE #define BONOBO_LISTENER (o) #define BONOBO_IS_LISTENER (o) #define BONOBO_LISTENER_CLASS (k) #define BONOBO_IS_LISTENER_CLASS (k) typedef BonoboListener; typedef BonoboListenerClass; void (*BonoboListenerCallbackFn) (BonoboListener *listener, char *event_name, CORBA_any *any, CORBA_Environment *ev, gpointer user_data); BonoboListener* bonobo_listener_new (BonoboListenerCallbackFn event_callback, gpointer user_data); char* bonobo_event_kind (const char *event_name); char* bonobo_event_type (const char *event_name); char* bonobo_event_subtype (const char *event_name); char* bonobo_event_idl_path (const char *event_name); char* bonobo_event_make_name (const char *idl_path, const char *kind, const char *subtype); |
The BonoboListener object is a CORBA server used to receive events emitted by a remote Bonobo::EventSource server. The combination EventSource/Listener is used to notify one or more client applications of events that happen in a component. Think of the EventSource/Listener as a notification/callback system that allows multiple clients to be informed of events.
Once created, the BonoboListener object needs to be attached to a remote IDL:Bonobo/EventSource:1.0 server. This is done by passing the CORBA Object reference of the BonoboListener to the addListener method in the IDL:Bonobo/EventSource:1.0.
The BonoboListener object allows the user to specify a callback function to be invoked when an event is emitted by the IDL:Bonobo/EventSource:1.0 server. The BonoboListener object also emits the "event_notify" Gtk+ signal, which allows you to connect multiple code segments to the same event notification.
Here is a sample client application that registers interest in being notified of events from the fictional "Keyboard" event source:
BonoboListener *keyboard_listener; my_listener_function (BonoboListener *l, char *event_name, CORBA_any value, CORBA_Environment *ev, gpointer user_data) { printf ("Received event named: s\n", event_name); } connect_to_keyboard_source (Bonobo_EventSource *keyboard) { Bonobo_Unknown reference; /* * First, create the listener Bonobo server. */ keyboard_listener = bonobo_listener_new (my_listener_function, NULL); /* * Now, register our listener with the EventSource */ reference = bonobo_object_corba_objref (keyboard_listener); Bonobo_EventSource_addListener (keyboard, reference); } |
The CORBA::any value passed to the listener function is defined by the contract between the EventSource's event you are using and you. To manipulate the value, you can use the CORBA DynamicAny interface to introspect the value and extract the information you need.
#define BONOBO_LISTENER(o) (GTK_CHECK_CAST ((o), BONOBO_LISTENER_TYPE, BonoboListener)) |
#define BONOBO_LISTENER_CLASS(k) (GTK_CHECK_CLASS_CAST((k), BONOBO_LISTENER_TYPE, BonoboListenerClass)) |
#define BONOBO_IS_LISTENER_CLASS(k) (GTK_CHECK_CLASS_TYPE ((k), BONOBO_LISTENER_TYPE)) |
typedef struct { BonoboXObjectClass parent_class; POA_Bonobo_Listener__epv epv; /* Signals */ void (* event_notify) (BonoboListener *listener, char *event_name, BonoboArg *event_data, CORBA_Environment *ev); } BonoboListenerClass; |
void (*BonoboListenerCallbackFn) (BonoboListener *listener, char *event_name, CORBA_any *any, CORBA_Environment *ev, gpointer user_data); |
The signature for the callback function invoked when an event is delivered to the BonoboListener object.
BonoboListener* bonobo_listener_new (BonoboListenerCallbackFn event_callback, gpointer user_data); |
Creates a generic event listener. The listener calls the event_callback function and emits an "event_notify" signal when notified of an event. The signal callback should be of the form:
<informalexample> <programlisting> void some_callback (BonoboListener *listener, char *event_name, CORBA_any *any, CORBA_Environment *ev, gpointer user_data); </programlisting> </informalexample>
You will typically pass the CORBA_Object reference in the return value to an EventSource (by invoking EventSource::addListener).
char* bonobo_event_make_name (const char *idl_path, const char *kind, const char *subtype); |
Creates an event name. Event names consist of three parts. The idl_path is mainly to create a unique namespace, and should identify the interface which triggered the event, for example "Bonobo/Property". The kind denotes what happened, for example "change". Finally you can use the optional subtype to make events more specific. All three parts of the name are joined together separated by colons. "Bonobo/Property:change" or "Bonobo/Property:change:autosave" are examples of valid event names.