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, Revert‐
ToPointerRoot, RevertToFollowKeyboard, or RevertToNone.
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 DeviceFocusIn
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 XSetDeviceFocus
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 support
this request will result in a BadMatch error. Whether or not given
device can support this request can be determined by the information
returned by XOpenDevice. For those devices that support focus, XOpen‐
Device 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 BadWin‐
dow 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 BadMatch
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 XOpen‐
InputDevice. This error may also occur if the specified
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 speci‐
fied 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 XSetDeviceFo‐
cus request was made specifying a device that the server
implementation does not allow to be focused.
SEE ALSO
Programming with Xlib
X Version 11 Release 6 XSetDeviceFocus(3X11)
