XSetDeviceFocus(3X11) X11 SDE 5.4R3.00 XSetDeviceFocus(3X11)
NAME
XSetDeviceFocus, XGetDeviceFocus - control extension input device
focus
SYNTAX
XSetDeviceFocus(display, device, focus, revertto, time)
Display *display;
Display *device;
Window focus;
int revertto;
Time time;
XGetDeviceFocus(display, device, focusreturn, reverttoreturn,
timereturn)
Display *display;
Display *device;
Window *focusreturn;
int *reverttoreturn;
int *timereturn;
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.
focusreturn
Returns the focus window, PointerRoot, FollowKeyboard, or
None.
revertto Specifies where the input focus reverts to if the window
becomes not viewable. You can pass RevertToParent,
RevertToPointerRoot, RevertToFollowKeyboard, or
RevertToNone.
reverttoreturn
Returns the current focus state RevertToParent,
RevertToPointerRoot, RevertToFollowKeyboard, or
RevertToNone.
timereturn 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
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XSetDeviceFocus(3X11) X11 SDE 5.4R3.00 XSetDeviceFocus(3X11)
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.
Otherwise, 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, 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
BadWindow errors.
The XGetDeviceFocus request returns the focus window and the current
focus state.
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XSetDeviceFocus(3X11) X11 SDE 5.4R3.00 XSetDeviceFocus(3X11)
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
XOpenInputDevice. 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
specified for an argument, the full range defined by the
argument'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
Window.
BadMatch This error may occur if an XGetDeviceFocus or
XSetDeviceFocus request was made specifying a device that
the server implementation does not allow to be focused.
SEE ALSO
Programming with Xlib
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