XOpenDisplay(3X11) XLIB FUNCTIONS XOpenDisplay(3X11)NAME
XOpenDisplay, XCloseDisplay - connect or disconnect to X
server
SYNTAX
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 XOpenDis-
play does not succeed, it returns NULL. After a success-
ful call to XOpenDisplay, all of the screens in the dis-
play can be used by the client. The screen number speci-
fied 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,
X Version 11 Release 6.4 1
XOpenDisplay(3X11) XLIB FUNCTIONS XOpenDisplay(3X11)
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 win-
dows, 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 ALSOAllPlanes(3X11), XFlush(3X11), XSetCloseDownMode(3X11)
Xlib - C Language X Interface
X Version 11 Release 6.4 2