NAME
XOpenDisplay, XCloseDisplay - connect or disconnect to X server
SYNTAX
Display
*XOpenDisplay(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 Interface