XSetDeviceFocus

XSetDeviceFocus(3X11)		 X FUNCTIONS		XSetDeviceFocus(3X11)



NAME
       XSetDeviceFocus,	 XGetDeviceFocus  -  control  extension	 input device
       focus

SYNTAX
       XSetDeviceFocus(display, device, focus, revert_to, time)
	     Display *display;
	     Display *device;
	     Window focus;
	     int revert_to;
	     Time time;

       XGetDeviceFocus(display,	  device,   focus_return,   revert_to_return,
       time_return)
	     Display *display;
	     Display *device;
	     Window *focus_return;
	     int *revert_to_return;
	     int *time_return;

ARGUMENTS
       display	   Specifies the connection to the X server.

       device	   Specifies  the  device  whose  focus	 is  to be queried or
		   changed.

       focus	   Specifies  the  window,  PointerRoot,  FollowKeyboard,  or
		   None.

       focus_return
		   Returns  the focus window, PointerRoot, FollowKeyboard, or
		   None.

       revert_to   Specifies where the input focus reverts to if  the  window
		   becomes   not  viewable.   You  can	pass  RevertToParent,
		   RevertToPointerRoot,	 RevertToFollowKeyboard,  or  Revert-
		   ToNone.

       revert_to_return
		   Returns  the current focus state RevertToParent, RevertTo-
		   PointerRoot, RevertToFollowKeyboard, or RevertToNone.

       time_return Returns the last_focus_time for the device.

       time	   Specifies the time.	You can pass either  a	timestamp  or
		   CurrentTime.

DESCRIPTION
       The  XSetDeviceFocus request changes the focus of the specified device
       and its last-focus-change time.	It has no  effect  if  the  specified
       time  is	 earlier  than the current last-focus-change time or is later
       than the current X server time.	Otherwise, the last-focus-change time
       is  set to the specified time CurrentTime is replaced by the current X
       server time).  XSetDeviceFocus causes the X server to generate Device-
       FocusIn and DeviceFocusOut events.

       Depending on the focus argument, the following occurs:

       ·    If	focus  is  None , all device events are discarded until a new
	    focus window is set, and the revert_to argument is ignored.

       ·    If focus is a window, it becomes the device’s focus window.	 If a
	    generated  device event would normally be reported to this window
	    or one of its inferiors, the event is reported as usual.   Other-
	    wise, the event is reported relative to the focus window.

       ·    If focus is PointerRoot, the focus window is dynamically taken to
	    be the root window of whatever screen the pointer is on  at	 each
	    event  from	 the  specified	 device.  In this case, the revert_to
	    argument is ignored.

       ·    If focus is FollowKeyboard, the focus window is dynamically taken
	    to	be  the	 window	 to which the X keyboard focus is set at each
	    input event.

       The specified focus window must be viewable at the time	XSetDeviceFo-
       cus is called, or a BadMatch error results.  If the focus window later
       becomes not viewable, the X server evaluates the revert_to argument to
       determine the new focus window as follows:

       ·    If	revert_to  is RevertToParent, the focus reverts to the parent
	    (or the closest viewable ancestor), and the new  revert_to	value
	    is taken to be RevertToNone.

       ·    If	revert_to  is RevertToPointerRoot, RevertToFollowKeyboard, or
	    RevertToNone, the focus reverts to	PointerRoot,  FollowKeyboard,
	    or None, respectively.

       When  the  focus	 reverts,  the	X  server generates DeviceFocusIn and
       DeviceFocusOut events, but the last-focus-change time is not affected.

       Input  extension devices are not required to support the ability to be
       focused.	 Attempting to set the focus of a device that does  not	 sup-
       port  this  request  will  result in a BadMatch error.  Whether or not
       given device can support this request can be determined by the  infor-
       mation returned by XOpenDevice.	For those devices that support focus,
       XOpenDevice  will  return  an  XInputClassInfo  structure   with	  the
       input_class  field  equal  to  the constant FocusClass (defined in the
       file XI.h).

       XSetDeviceFocus can generate BadDevice, BadMatch, BadValue,  and	 Bad-
       Window errors.

       The  XGetDeviceFocus  request returns the focus window and the current
       focus state.

       Not all input extension devices can be focused.	Attempting  to	query
       the  focus  state  of a device that can’t be focused results in a Bad-
       Match error.  A device that can be  focused  returns  information  for
       input Class Focus when an XOpenDevice request is made.

       XGetDeviceFocus can generate BadDevice, and BadMatch errors.

DIAGNOSTICS
       BadDevice   An  invalid	device	was  specified.	 The specified device
		   does not exist or has not been opened by this  client  via
		   XOpenInputDevice.  This error may also occur if the speci-
		   fied device is the X keyboard or X pointer device.

       BadValue	   Some numeric value  falls  outside  the  range  of  values
		   accepted by the request.  Unless a specific range is spec-
		   ified for an argument, the full range defined by the argu-
		   ment’s type is accepted.  Any argument defined as a set of
		   alternatives can generate this error.

       BadWindow   A value for a Window argument does not name a defined Win-
		   dow.

       BadMatch	   This	 error may occur if an XGetDeviceFocus or XSetDevice-
		   Focus request was made specifying a device that the server
		   implementation does not allow to be focused.

SEE ALSO
       Programming with Xlib



							XSetDeviceFocus(3X11)