General
Mainloop and event handling
GTK uses an event oriented programming model. While conventional C programs
have control over the program flow all the time this does not apply to
applications written using GTK. Instead you set up some objects and
register some functions (callbacks
) to be called whenever
some event occurs and give control to the GTK mainloop (e.g. by calling
gtk_main).
Typical <function>main</function> function for a GTK application
int
main (int argc, char **argv)
{
/* Initialize i18n support */
gtk_set_locale ();
/* Initialize the widget set */
gtk_init (&argc, &argv);
/* Create the main window */
mainwin = gtk_window_new (GTK_WINDOW_TOPLEVEL);
/* Set up our GUI elements */
...
/* Show the application window */
gtk_widget_showall (mainwin);
/* Let the user interact with our application */
gtk_main ();
/* The user lost interest */
gtk_exit (0);
}
Sets the current locale according to the program environment. This is the
same as calling the libc function setlocale(LC_ALL, "") but also takes
care of the locale specific setup of the windowing system used by GDK.
You should call this function before gtk_init to
support internationalization of your GTK+ applications.
@Returns: A string corresponding to the locale set.
Call this function before using any other GTK functions in your GUI
applications. It will initialize everything needed to operate the toolkit and
parses some standard command line options. argc and
argv are adjusted accordingly so your own code will
never see those standard arguments.
This function will terminate your program if it was unable to initialize
the GUI for some reason. If you want your program to fall back to a
textual interface you want to call gtk_init_check
instead.
@argc: Address of the argc parameter of your
main function. Changed if any arguments were
handled.
@argv: Address of the argv parameter of
main. Any parameters understood by
gtk_init are stripped before return.
This function does the same work as gtk_init with only
a single change: It does not terminate the program if the GUI can't be
initialized. Instead it returns %FALSE on failure.
This way the application can fall back to some other means of communication
with the user - for example a curses or command line interface.
@argc: A reference to the argc of the main
function.
@argv: A reference to the argv of the main
function.
@Returns: %TRUE if the GUI has been successful initialized,
%FALSE otherwise.
Terminate the program and return the given exit code to the caller.
This function will shut down the GUI and free all resources allocated
for GTK.
@error_code: Return value to pass to the caller. This is dependend on the
target system but at least on Unix systems %0 means
success.
Check if any events are pending. This can be used to update the GUI
and invoke timeouts etc. while doing some time intensive computation.
Updating the GUI during a long computation
/* computation going on */
...
while (gtk_events_pending ())
gtk_main_iteration ();
...
/* computation continued */
@Returns: %TRUE if any events are pending, %FALSE otherwise.
@Returns:
@Returns:
@blocking:
@Returns:
@event:
@argc:
@argv:
All this function does it to return TRUE. This can be useful for example
if you want to inhibit the deletion of a window. Of course you should
not do this as the user expects a reaction from clicking the close
icon of the window...
A persistent window
##include <gtk/gtk.h>
int
main (int argc, char **argv)
{
GtkWidget *win, *but;
gtk_init( &argc, &argv );
win = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_signal_connect (GTK_OBJECT(win), "delete-event",
(GtkSignalFunc) gtk_true, NULL);
gtk_signal_connect (GTK_OBJECT(win), "destroy",
(GtkSignalFunc) gtk_main_quit, NULL);
but = gtk_button_new_with_label ("Close yourself. I mean it!");
gtk_signal_connect_object (
GTK_OBJECT (but), "clicked",
(GtkSignalFunc) gtk_object_destroy, (gpointer) win );
gtk_container_add (GTK_CONTAINER (win), but);
gtk_widget_show_all (win);
gtk_main ();
return 0;
}
@Returns: %TRUE
Analogical to gtk_true this function does nothing
but always returns %FALSE.
@Returns: %FALSE
@widget:
@Returns:
@widget:
@function:
@data:
@main_level:
@object:
@main_level:
@function:
@data:
@Returns:
@main_level:
@function:
@marshal:
@data:
@destroy:
@Returns:
@quit_handler_id:
@data:
@interval:
@function:
@marshal:
@data:
@destroy:
@Returns:
@interval:
@function:
@data:
@Returns:
@timeout_handler_id:
@function:
@data:
@Returns:
@priority:
@function:
@data:
@Returns:
@priority:
@function:
@marshal:
@data:
@destroy:
@Returns:
@idle_handler_id:
@data:
@source:
@condition:
@function:
@marshal:
@data:
@destroy:
@Returns:
@input_handler_id:
@snooper:
@func_data:
@Returns:
@grab_widget:
@event:
@func_data:
@Returns:
@snooper_handler_id:
@Returns:
@event:
@Returns:
@widget:
@event: