XOpenDisplay(3X11)XOpenDisplay(3X11)NAME
XOpenDisplay, XCloseDisplay - connect or disconnect to X server
SYNOPSIS
Display *XOpenDisplay(display_name)
char *display_name;
XCloseDisplay(display)
Display *display;
ARGUMENTS
Specifies the connection to the X server. Specifies the hardware dis‐
play 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 win‐
dows, resource IDs (Window, Font, Pixmap, Colormap, Cursor, and GCon‐
text), or other resources that the client has created on this display,
unless the close-down mode of the resource has been changed (see XSet‐
CloseDownMode). Therefore, these windows, resource IDs, and other
resources should never be referenced again or an error will be gener‐
ated. 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
XOpenDisplay(3X11)