XtDisplayInitialize(3Xt) XT FUNCTIONS XtDisplayInitialize(3Xt)NAME
XtDisplayInitialize, XtOpenDisplay, XtDatabase, XtScreen-
Database, XtCloseDisplay - initialize, open, or close a
display
SYNTAX
void XtDisplayInitialize(app_context, display, applica-
tion_name, application_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, appli-
cation_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
argc Specifies a pointer to the number of command
line parameters.
argv Specifies the command line parameters.
app_context
Specifies the application context.
application_class
Specifies the class name of this application,
which usually is the generic name for all
instances of this application.
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XtDisplayInitialize(3Xt) XT FUNCTIONS XtDisplayInitialize(3Xt)
application_name
Specifies the name of the application instance.
display Specifies the display. Note that a display can
be in at most one application context.
num_options
Specifies the number of entries in the options
list.
options 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.
screen 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 performs other per display initial-
ization. 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 compo-
nent 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 XtDefaultFore-
ground and XtDefaultBackground for widgets created on this
display. (See Section 9.6.1).
The XtOpenDisplay function calls XOpenDisplay the speci-
fied display name. If display_string is NULL, XtOpen-
Display 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
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XtDisplayInitialize(3Xt) XT FUNCTIONS XtDisplayInitialize(3Xt)
application programmer.
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 dis-
patch is complete. Note that applications need only call
XtCloseDisplay if they are to continue executing after
closing the display; otherwise, they should call XtDe-
stroyApplicationContext 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 XtDisplayInitialize, the results
are not defined.
The XtScreenDatabase function returns the fully merged
resource database associated with the specified screen. If
the screen does not belong to a Display initilized by
XtDisplayInitialize, the results are undefined.
SEE ALSOXtAppCreateShell(3Xt), XtCreateApplicationContext(3Xt)
X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface
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