XtDisplayInitialize(3Xt)XtDisplayInitialize(3Xt)NAME
XtDisplayInitialize, XtOpenDisplay, XtDatabase, XtScreenDatabase,
XtCloseDisplay - initialize, open, or close a display
SYNOPSIS
void XtDisplayInitialize(app_context, display, application_name, appli‐
cation_class, options, num_options, argc, argv)
XtAppContext app_context;
Display *display;
String application_name;
String application_class;
XrmOptionDescRec *options;
Cardinal num_options;
int *argc;
String *argv;
Display *XtOpenDisplay(app_context, display_string, application_name,
application_class, options, num_options, argc, argv)
XtAppContext app_context;
String display_string;
String application_name;
String application_class;
XrmOptionDescRec *options;
Cardinal num_options;
int *argc;
String *argv;
void XtCloseDisplay(display)
Display *display;
XrmDatabase XtDatabase(display)
Display *display;
XrmDatabase XtScreenDatabase(screen)
Screen* screen;
ARGUMENTS
Specifies a pointer to the number of command line parameters. Speci‐
fies the command line parameters. Specifies the application context.
Specifies the class name of this application, which usually is the
generic name for all instances of this application. Specifies the name
of the application instance. Specifies the display. Note that a dis‐
play can be in at most one application context. Specifies the number
of entries in the options list. Specifies how to parse the command
line for any application-specific resources. The options argument is
passed as a parameter to XrmParseCommand. For further information, see
Xlib -- C Language X Interface. Specifies the screen whose resource
database is to be returned.
DESCRIPTION
The XtDisplayInitialize function builds the resource database, calls
the Xlib XrmParseCommand function to parse the command line, and per‐
forms other per display initialization. After XrmParseCommand has been
called, argc and argv contain only those parameters that were not in
the standard option table or in the table specified by the options
argument. If the modified argc is not zero, most applications simply
print out the modified argv along with a message listing the allowable
options. On UNIX-based systems, the application name is usually the
final component of argv[0]. If the synchronize resource is True for the
specified application, XtDisplayInitialize calls the Xlib XSynchronize
function to put Xlib into synchronous mode for this display connection.
If the reverseVideo resource is True, the Intrinsics exchange XtDe‐
faultForeground and XtDefaultBackground for widgets created on this
display. (See Section 9.6.1).
The XtOpenDisplay function calls XOpenDisplay the specified display
name. If display_string is NULL, XtOpenDisplay uses the current value
of the -display option specified in argv and if no display is specified
in argv, uses the user's default display (on UNIX-based systems, this
is the value of the DISPLAY environment variable).
If this succeeds, it then calls XtDisplayInitialize and pass it the
opened display and the value of the -name option specified in argv as
the application name. If no name option is specified, it uses the
application name passed to XtOpenDisplay. If the application name is
NULL, it uses the last component of argv[0]. XtOpenDisplay returns the
newly opened display or NULL if it failed.
XtOpenDisplay is provided as a convenience to the application program‐
mer.
The XtCloseDisplay function closes the specified display as soon as it
is safe to do so. If called from within an event dispatch (for example,
a callback procedure), XtCloseDisplay does not close the display until
the dispatch is complete. Note that applications need only call
XtCloseDisplay if they are to continue executing after closing the dis‐
play; otherwise, they should call XtDestroyApplicationContext or just
exit.
The XtDatabase function returns the fully merged resource database that
was built by XtDisplayInitialize associated with the display that was
passed in. If this display has not been initialized by XtDisplayIni‐
tialize, the results are not defined.
The XtScreenDatabase function returns the fully merged resource data‐
base associated with the specified screen. If the screen does not
belong to a Display initialized by XtDisplayInitialize, the results are
undefined.
NOTES
In internationalized applications, the XtSetLanguageProc function sets
the language procedure for XtDisplayInitialize. In such applications,
the catopen call must execute following the call to XtDisplayInitial‐
ize. (Remember that XtAppInitialize indirectly calls XtDisplayInitial‐
ize through XtOpenDisplay).
If the catopen call executes after XtSetLanguageProc but before the
call that initializes the display, the application does not access
translated messages when these are available for the language setting.
SEE ALSOcatopen(3), XtAppCreateShell(3Xt), XtAppInitialize(3Xt), XtCreateAppli‐
cationContext(3Xt)
X Toolkit Intrinsics -- C Language Interface
Xlib -- C Language X Interface
XtDisplayInitialize(3Xt)
