XOpenDisplay(3) XLIB FUNCTIONS XOpenDisplay(3)
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
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.
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). 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 InterfaceX Version 11 libX11 1.8.10 XOpenDisplay(3)
