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X11R7.4 - man page for xopendevice (x11r4 section 3)

XOpenDevice(3)				   X FUNCTIONS				   XOpenDevice(3)

NAME
       XOpenDevice, XCloseDevice - open or close an extension input device

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

       XCloseDevice(Display *display, XDevice *device);

ARGUMENTS
       display	   Specifies the connection to the X server.

       device_id   Specifies the id of the device to be opened

       device	   Specifies the device to be closed

DESCRIPTION
       The  XOpenDevice request makes an input device accessible to a client through input exten-
       sion 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.

STRUCTURES
       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,  Focus-
       Class,  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,  DeviceButton-
       Relese,	DeviceMotionNotify,  DeviceFocusIn,  DeviceFocusOut,  ProximityIn,  ProximityOut,
       DeviceStateNotify,  DeviceMappiingNotify,   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  XNex-
       tEvent, the type can be used for comparison with the type in the event.

DIAGNOSTICS
       BadDevice   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.

SEE ALSO
       Programming with Xlib

X Version 11				   libXi 1.2.1				   XOpenDevice(3)


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