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.TH XkbQueryExtension 3 "libX11 1.8.7" "X Version 11" "XKB FUNCTIONS"
.SH NAME
XkbQueryExtension \-  Determines the compatibility of a library at runtime.
.SH SYNOPSIS
.HP
.B Bool XkbQueryExtension
.BI "(\^Display *" "dpy" "\^,"
.BI "int *" "opcode_rtrn" "\^,"
.BI "int *" "event_rtrn" "\^,"
.BI "int *" "error_rtrn" "\^,"
.BI "int *" "major_in_out" "\^,"
.BI "int *" "minor_in_out" "\^);"
.if n .ti +5n
.if t .ti +.5i
.SH ARGUMENTS
.TP
.I dpy
connection to the X server
.TP
.I opcode_rtrn
backfilled with the major extension opcode
.TP
.I event_rtrn
backfilled with the extension base event code
.TP
.I error_rtrn
backfilled with the extension base error code
.TP
.I major_in_out
compile time lib major version in, server major version out
.TP
.I minor_in_out
compile time lib min version in, server minor version out 
.SH DESCRIPTION
.LP
Call 
.I XkbQueryExtension 
to check for the presence and compatibility of the 
extension in the server and to initialize the extension. Because of potential 
version mismatches, you cannot use the generic extension mechanism functions 
(
.I XQueryExtension 
and 
.I XInitExtension
) for checking for the presence of, and 
initializing the Xkb extension.
 
You must call 
.I XkbQueryExtension 
or 
.I XkbOpenDisplay 
before using any other Xkb 
library interfaces, unless such usage is explicitly allowed in the interface 
description in this document. The exceptions are: 
.I XkbIgnoreExtension, XkbLibraryVersion, 
and a handful of audible-bell functions. You should not use 
any other Xkb functions if the extension is not present or is uninitialized. In 
general, calls to Xkb library functions made prior to initializing the Xkb 
extension cause BadAccess protocol errors.

.I XkbQueryExtension 
both determines whether a compatible Xkb extension is present 
in the X server and initializes the extension when it is present.

The 
.I XkbQueryExtension 
function determines whether a compatible version of the X 
Keyboard Extension is present in the server. If a compatible extension is 
present, 
.I XkbQueryExtension 
returns True; otherwise, it returns False. 

If a compatible version of Xkb is present, 
.I XkbQueryExtension 
initializes the 
extension. It backfills the major opcode for the keyboard extension in
.I opcode_rtrn, 
the base event code in 
.I event_rtrn, 
the base error code in
.I error_rtrn, 
and the major and minor version numbers of the extension in
.I major_in_out 
and 
.I minor_in_out. 
The major opcode is reported in the 
.I req_major 
fields of some Xkb events. For a discussion of the base event code. 
.SH "RETURN VALUES"
.TP 15
True
The 
.I XkbQueryExtension 
function returns True if it determines a compatible version of the X 
Keyboard Extension is present in the server. 
.TP 15
False
The 
.I XkbQueryExtension 
function returns False if it determines a compatible version of the X 
Keyboard Extension is not present in the server.
.SH "SEE ALSO"
.BR XkbIgnoreExtension (3),
.BR XkbLibraryVersion (3),
.BR XkbOpenDisplay (3)