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       XOpenDevice, XCloseDevice - open	or close an extension input device

       #include	<X11/extensions/XInput.h>

       XDevice *XOpenDevice( Display *display,
			     XID device_id);

       XCloseDevice( Display *display,
		     XDevice *device);

	      Specifies	the connection to the X	server.

	      Specifies	the id of the device to	be opened

	      Specifies	the device to be closed

	   The XOpenDevice request makes an input device accessible to a
	   client through input	extension protocol requests. If
	   successful, it returns a pointer to an XDevice structure.

	   The XCloseDevice request makes an input device inaccessible to
	   a client through input extension protocol requests. Before
	   terminating,	and client that	has opened input devices through
	   the input extension should close them via CloseDevice.

	   When	a client makes an XCloseDevice request,	any active grabs
	   that	the client has on the device are released. Any event
	   selections that the client has are deleted, as well as any
	   passive grabs. If the requesting client is the last client
	   accessing the device, the server may	disable	all access by X	to
	   the device.

	   XOpenDevice and XCloseDevice	can generate a BadDevice error.


	   The XDevice structure returned by XOpenDevice contains:
			typedef	struct {
			XID device_id;
			int num_classes;
			XInputClassInfo	*classes;
			} XDevice;

	   The classes field is	a pointer to an	array of XInputClassInfo
	   structures. Each element of this array contains an event type
	   base	for a class of input supported by the specified	device.
	   The num_classes field indicates the number of elements in the
	   classes array.

	   The XInputClassInfo structure contains:

	   typedef struct {
	       unsigned	char input_class;
	       unsigned	char event_type_base;
	   } XInputClassInfo;

	   The input_class field identifies one	class of input supported
	   by the device. Defined types	include	KeyClass, ButtonClass,
	   ValuatorClass, ProximityClass, FeedbackClass, FocusClass, and
	   OtherClass. The event_type_base identifies the event	type of
	   the first event in that class.

	   The information contained in	the XInputClassInfo structure is
	   used	by macros to obtain the	event classes that clients use in
	   making XSelectExtensionEvent	requests. Currently defined macros
	   include DeviceKeyPress, DeviceKeyRelease, DeviceButtonPress,
	   DeviceButtonRelese, DeviceMotionNotify, DeviceFocusIn,
	   DeviceFocusOut, ProximityIn,	ProximityOut, DeviceStateNotify,
	   DeviceMappingNotify,	ChangeDeviceNotify,
	   DevicePointerMotionHint, DeviceButton1Motion,
	   DeviceButton2Motion,	DeviceButton3Motion, DeviceButton4Motion,
	   DeviceButton5Motion,	DeviceButtonMotion, DeviceOwnerGrabButton,
	   DeviceButtonPressGrab, and NoExtensionEvent.

	   To obtain the proper	event class for	a particular device, one
	   of the above	macros is invoked using	the XDevice structure for
	   that	device.	For example,
			DeviceKeyPress (*device, type, eventclass);

	   returns the DeviceKeyPress event type and the eventclass for
	   DeviceKeyPress events from the specified device.

	   This	eventclass can then be used in an XSelectExtensionEvent
	   request to ask the server to	send DeviceKeyPress events from
	   this	device.	When a selected	event is received via XNextEvent,
	   the type can	be used	for comparison with the	type in	the event.

		  An invalid device was	specified. The specified device
		  does not exist, or is	the X keyboard or X pointer. This
		  error	may also occur if some other client has	caused the
		  specified device to become the X keyboard or X pointer
		  device via the XChangeKeyboardDevice or
		  XChangePointerDevice requests.

				  06/19/2019			XOPENDEVICE(3)


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