XOpenDisplay
Section: XLIB FUNCTIONS (3)
Updated: libX11 1.7.0
Page Index
NAME
XOpenDisplay, XCloseDisplay - connect or disconnect to X server
SYNTAX
-
- Display *XOpenDisplay(_Xconst char *display_name);
-
- int XCloseDisplay(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
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.
The
XCloseDisplay
function closes the connection to the X server for the display specified in the
Display
structure and destroys all windows, resource IDs
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).
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.
SEE ALSO
AllPlanes(3),
XFlush(3),
XSetCloseDownMode(3)
Xlib - C Language X Interface