Event Control

These functions are used to dispatch events generated from the various other GEIS components. More...

Topics
	Input Devices

Data Structures
class	GeisEvent
	A generic GEIS event. More...

Vendor-defined Configuration Items
These configuration items are not a part of the GEIS specification and may change.
enum	_GeisEventType {   GEIS_EVENT_DEVICE_AVAILABLE , GEIS_EVENT_DEVICE_UNAVAILABLE , GEIS_EVENT_CLASS_AVAILABLE , GEIS_EVENT_CLASS_CHANGED ,   GEIS_EVENT_CLASS_UNAVAILABLE , GEIS_EVENT_GESTURE_BEGIN , GEIS_EVENT_GESTURE_UPDATE , GEIS_EVENT_GESTURE_END ,   GEIS_EVENT_TENTATIVE_BEGIN , GEIS_EVENT_TENTATIVE_UPDATE , GEIS_EVENT_TENTATIVE_END , GEIS_EVENT_INIT_COMPLETE ,   GEIS_EVENT_USER_DEFINED , GEIS_EVENT_ERROR }
typedef enum _GeisEventType	GeisEventType
typedef void(*	GeisEventCallback) (Geis geis, GeisEvent event, void *context)
	The application callback type for the event dispatcher.
void	geis_register_event_callback (Geis geis, GeisEventCallback event_callback, void *context)
	Registers an event-handler callback.
GeisStatus	geis_dispatch_events (Geis geis)
	Pumps the GEIS event loop.
GeisStatus	geis_next_event (Geis geis, GeisEvent *event)
	Retrieves the next queued GEIS event.
void	geis_event_delete (GeisEvent event)
	Destroys a GeisEvent.
GeisEventType	geis_event_type (GeisEvent event)
	Gets the type of the event.
GeisSize	geis_event_attr_count (GeisEvent event)
	Gets the number of attributes in the event.
GeisAttr	geis_event_attr (GeisEvent event, GeisSize index)
	Gets an indicated attribute from the event.
GeisAttr	geis_event_attr_by_name (GeisEvent event, GeisString attr_name)
	Gets a named attribute from the event.
#define	GEIS_DEFAULT_EVENT_CALLBACK
	A special constant indicating the use of the default event callback.

Detailed Description

These functions are used to dispatch events generated from the various other GEIS components.

Applications must invoke geis_dispatch_events() from time to time to generate input device, gesture type, and gesture events. The GEIS events are then retrieved either from the internal event queue using the geis_next_event() call or through an application-supplied callback set through the geis_register_event_callback() call.

Macro Definition Documentation

GEIS_DEFAULT_EVENT_CALLBACK

#define GEIS_DEFAULT_EVENT_CALLBACK

A special constant indicating the use of the default event callback.

Typedef Documentation

GeisEventCallback

typedef void(* GeisEventCallback) (Geis geis, GeisEvent event, void *context)

The application callback type for the event dispatcher.

Parameters

[in]	geis	the GEIS API instance
[in]	event	the opaque event pointer
[in]	context	the application-supplied context value

Function Documentation

geis_dispatch_events()

GeisStatus geis_dispatch_events

(

Geis

geis

)

Pumps the GEIS event loop.

Parameters

[in]

geis

The GEIS API instance.

Processes input events until there are no more input events to process and generates zero or more gesture events, reporting them via the user-supplied callback or pushing them on the internal event queue for retrieval via the geis_next_event() call.

Return values

GEIS_STATUS_SUCCESS	The event loop was successfully pumped and no further events remain to be processed at this time.
GEIS_STATUS_CONTINUE	The event loop was successfully pumped but the system detected there are events still remaining to be processed.
GEIS_STATUS_UNKNOWN_ERROR	Some error occurred

Examples

geis2.c.

geis_event_attr()

GeisAttr geis_event_attr	(	GeisEvent	event,
		GeisSize	index )

Gets an indicated attribute from the event.

Parameters

[in]	event	The GeisEvent.
[in]	index	Indicates the attribute to retrieve.

geis_event_attr_by_name()

GeisAttr geis_event_attr_by_name	(	GeisEvent	event,
		GeisString	attr_name )

Gets a named attribute from the event.

Parameters

[in]	event	The GeisEvent.
[in]	attr_name	The name of the attribute to retrieve.

geis_event_attr_count()

GeisSize geis_event_attr_count

(

GeisEvent

event

)

Gets the number of attributes in the event.

Parameters

[in]

event

The GeisEvent.

geis_event_delete()

void geis_event_delete

(

GeisEvent

event

)

Destroys a GeisEvent.

Parameters

[in]

event

The GeisEvent to destroy.

geis_event_type()

GeisEventType geis_event_type

(

GeisEvent

event

)

Gets the type of the event.

Parameters

[in]

event

The GeisEvent to destroy.

geis_next_event()

GeisStatus geis_next_event	(	Geis	geis,
		GeisEvent *	event )

Retrieves the next queued GEIS event.

Parameters

[in]	geis	The GEIS API instance.
[out]	event	The GeisEvent retrieved, if any.

Pulls the next available GeisEvent from the internal event queue, if any, and indicates whether there are more events left.

Return values

GEIS_STATUS_SUCCESS	An event was successfully pulled from the queue and the queue is now empty.
GEIS_STATUS_CONTINUE	An event was successfully pulled from the queue and one or more events remain in the queue.
GEIS_STATUS_EMPTY	No event was pulled from the queue because it is empty. The value of *event remains unchanged.
GEIS_STATUS_UNKNOWN_ERROR	Some error occurred

Examples

geis2.c.

geis_register_event_callback()

void geis_register_event_callback	(	Geis	geis,
		GeisEventCallback	event_callback,
		void *	context )

Registers an event-handler callback.

Parameters

[in]	geis	the GEIS API instance
[in]	event_callback	the callback to register
[in]	context	the caller context

This function registers the callback to be executed whenever a new GeisEvent is generated. The default function pushes the GeisEvent onto an internal queue to be picked up by a call to geis_next_event().

Calling geis_register_event_callback() with a callback of GEIS_DEFAULT_EVENT_CALLBACK replaces any registered function wit hthe default function.

The callback is executed in the same thread context as the one geis_dispatch_events() is called from.