.\"
.\" Copyright \(co 1985, 1986, 1987, 1988, 1989, 1990, 1991 by
.\" Digital Equipment Corporation
.\"
.\" Portions Copyright \(co 1990, 1991 by
.\" Tektronix, Inc
.\"
.\" Rewritten for X.org by Chris Lee <clee@freedesktop.org>
.\"
.\" Permission to use, copy, modify, distribute, and sell this documentation
.\" for any purpose and without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\" Chris Lee makes no representations about the suitability for any purpose
.\" of the information in this document.  It is provided \`\`as-is\*(rq without
.\" express or implied warranty.
.\"
.ds xL Programming with Xlib
.TH XQueryExtension 3 "libX11 1.8.10" "X Version 11" "X FUNCTIONS"
.SH NAME
XQueryExtension, XListExtensions, XFreeExtensionList \- list available extensions
.SH SYNTAX
.HP
Bool XQueryExtension(\^\fIdisplay, \fIname\fP, \fImajor_opcode_return\fP, \fIfirst_event_return\fP, \fIfirst_error_return\fP\^)
.HP
char **XListExtensions(\^\fIdisplay\fP, \fInextensions_return\fP\^)
.HP
XFreeExtensionList(\^\fIlist\fP\^)
.SH ARGUMENTS
.IP \fIdisplay\fP 1i
Specifies the connection to the X server.
.IP \fIname\fP 1i
Specifies the extension name.
.IP \fImajor_opcode_return\fP 1i
Returns the major opcode.
.IP \fIfirst_event_return\fP 1i
Returns the first event code, if any.
.IP \fIfirst_error_return\fP 1i
Returns the first error code, if any.
.IP \fInextensions_return\fP 1i
Returns the number of extensions listed.
.IP \fIlist\fP 1i
Specifies the list of extension names.
.SH DESCRIPTION
.LP
The \fIXQueryExtension\fP function determines if the named extension is
present.
If the extension is not present, \fIXQueryExtension\fP returns
\fIFalse\fP; otherwise, it returns \fITrue\fP.  If the extension is present,
\fIXQueryExtension\fP returns the major opcode for the extension to
major_opcode_return; otherwise, it returns zero.
Any minor opcode and the
request formats are specific to the extension.
If the extension involves
additional event types, \fIXQueryExtension\fP returns the base event type code
to first_event_return; otherwise, it returns zero.
The format of the events is
specific to the extension.
If the extension involves additional error codes,
\fIXQueryExtension\fP returns the base error code to first_error_return;
otherwise, it returns zero.
The format of additional data in the errors is
specific to the extension.
If the extension name is not in the Host Portable
Character Encoding the result is implementation-dependent.
Uppercase and
lowercase matter; the strings \*(lqthing\*(rq, \*(lqThing\*(rq, and \*(lqthinG\*(rq are all
considered different names.
.LP
The \fIXListExtensions\fP function returns a list of all extensions supported
by the server.
If the data returned by the server is in the Latin Portable
Character Encoding, then the returned strings are in the Host Portable
Character Encoding.
Otherwise, the result is implementation-dependent.
.LP
The \fIXFreeExtensionList\fP function frees the memory allocated by
\fIXListExtensions\fP.