X Version 11 (Release 6.1)
XOpenDisplay(X3xlib)
XOpenDisplay --
connect or disconnect to X server
Synopsis
Display *XOpenDisplay(display_name)
char *display_name;
XCloseDisplay(display)
Display *display;
Arguments
display-
Specifies the connection to the X server.
display_name-
Specifies the hardware display name, which determines the display
and communications domain to be used.
On a POSIX-conformant system,
if the display_name is NULL,
it defaults to the value of the DISPLAY environment variable.
Description
The XOpenDisplay function returns a Display
structure that serves as the connection to the X server and that
contains all the information about that X server.
XOpenDisplay connects your application to the X server
through TCP or DECnet communications protocols,
or through some local inter-process communication protocol.
If the hostname is a host machine name and a single colon (:)
separates the hostname and display number,
XOpenDisplay connects using TCP streams.
If the hostname is not specified,
Xlib uses whatever it believes is the fastest transport.
If the hostname is a host machine name and a double colon (::)
separates the hostname and display number,
XOpenDisplay connects using DECnet.
A single X server can support any or all of these transport mechanisms
simultaneously.
A particular Xlib implementation can support many more of these transport
mechanisms.
If successful, XOpenDisplay returns a pointer to a
Display structure, which is defined in
X11/Xlib.h.
If XOpenDisplay does not succeed, it returns NULL.
After a successful call to XOpenDisplay,
all of the screens in the display can be used by the client.
The screen number specified in the display_name argument is returned
by the DefaultScreen macro (or the XDefaultScreen
function).
You can access elements of the Display
and Screen structures only by using
the information macros or functions.
For information about using macros and functions to
obtain information from the Display structure,
see section 2.2.1 of Xlib - C Language X Interface.
The XCloseDisplay function closes the connection
to the X server for the display specified in the Display
structure and destroys all windows, resource IDs
(Window, Font, Pixmap,
Colormap, Cursor, and GContext),
or other resources that the client has created on this display,
unless the close-down mode of the resource has been changed (see
XSetCloseDownMode(X3xlib)).
Therefore, these windows, resource IDs,
and other resources should never be
referenced again or an error will be generated.
Before exiting, you should call XCloseDisplay
explicitly so that any pending errors are reported as
XCloseDisplay performs a final XSync operation.
XCloseDisplay can generate a ``BadGC'' error.
References
AllPlanes(X3xlib),
XFlush(X3xlib),
XSetCloseDownMode(X3xlib)
Xlib - C Language X Interface
© 2004 The SCO Group, Inc. All rights reserved.
UnixWare 7 Release 7.1.4 - 25 April 2004