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.\" Title: xsetdevicefocus
.\" Author: [FIXME: author] [see http://www.docbook.org/tdg5/en/html/author]
.\" Generator: DocBook XSL Stylesheets vsnapshot
.\" Date: 05/04/2023
.\" Manual: \ \&
.\" Source: \ \&
.\" Language: English
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.TH "XSETDEVICEFOCUS" "3" "05/04/2023" "\ \&" "\ \&"
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.SH "NAME"
XSetDeviceFocus, XGetDeviceFocus \- control extension input device focus
.SH "SYNOPSIS"
.sp
.nf
#include
.fi
.sp
.nf
XSetDeviceFocus( Display *display,
XDevice *device,
Window focus,
int revert_to,
Time time);
.fi
.sp
.nf
XGetDeviceFocus( Display *display,
XDevice *device,
Window *focus_return,
int *revert_to_return,
int * time_return);
.fi
.sp
Arguments
.sp
.nf
display
Specifies the connection to the X server\&.
.fi
.sp
.nf
device
Specifies the device whose focus is to be queried or
changed\&.
.fi
.sp
.nf
focus
Specifies the window, PointerRoot, FollowKeyboard, or
None\&.
.fi
.sp
.nf
focus_return
Returns the focus window, PointerRoot, FollowKeyboard, or
None\&.
.fi
.sp
.nf
revert_to
Specifies where the input focus reverts to if the window
becomes not viewable\&. You can pass RevertToParent,
RevertToPointerRoot, RevertToFollowKeyboard, or
RevertToNone\&.
.fi
.sp
.nf
revert_to_return
Returns the current focus state RevertToParent,
RevertToPointerRoot, RevertToFollowKeyboard, or
RevertToNone\&.
.fi
.sp
.nf
time_return
Returns the last_focus_time for the device\&.
.fi
.sp
.nf
time
Specifies the time\&. You can pass either a timestamp or
CurrentTime\&.
.fi
.SH "DESCRIPTION"
.sp
.if n \{\
.RS 4
.\}
.nf
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\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
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\*(Aqs 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\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
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\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
When the focus reverts, the X server generates DeviceFocusIn
and DeviceFocusOut events, but the last\-focus\-change time is
not affected\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
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)\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
XSetDeviceFocus can generate BadDevice, BadMatch, BadValue, and
BadWindow errors\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
The XGetDeviceFocus request returns the focus window and the
current focus state\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
Not all input extension devices can be focused\&. Attempting to
query the focus state of a device that can\*(Aqt 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\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
XGetDeviceFocus can generate BadDevice, and BadMatch errors\&.
.fi
.if n \{\
.RE
.\}
.SH "DIAGNOSTICS"
.sp
.if n \{\
.RS 4
.\}
.nf
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\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
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\*(Aqs type is accepted\&. Any argument defined as a
set of alternatives can generate this error\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
BadWindow
A value for a Window argument does not name a defined
Window\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
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\&.
.fi
.if n \{\
.RE
.\}