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GTK+ General section started, from Torsten Landschoff <torsten@debian.org>

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GTK+ General section started, from Torsten Landschoff <torsten@debian.org>
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Damon Chaplin 1999-12-19 21:08:48 +00:00
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159
docs/reference/gtk/tmpl/gtkmain.sgml
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@ -2,59 +2,143 @@
General
<!-- ##### SECTION Short_Description ##### -->
Mainloop and event handling
<!-- ##### SECTION Long_Description ##### -->
<para>
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 (<quote>callbacks</quote>) to be called whenever
some event occurs and give control to the GTK mainloop (e.g. by calling
<function>gtk_main</function>).
</para>
<example>
<title> Typical <function>main</function> function for a GTK application</title>
<programlisting>
int
main (int argc, char **argv)
{
/* Initialize i18n support */
gtk_set_locale ();
/* Initialize the widget set */
gtk_init (&amp;argc, &amp;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);
}
</programlisting>
</example>
<!-- ##### SECTION See_Also ##### -->
<para>
</para>
<!-- ##### FUNCTION gtk_set_locale ##### -->
<para>
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.
</para>
@Returns:
<para>
You should call this function before <function>gtk_init</function> to
support internationalization of your GTK+ applications.
</para>
@Returns: A string corresponding to the locale set.
<!-- ##### FUNCTION gtk_init ##### -->
<para>
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. <parameter>argc</parameter> and
<parameter>argv</parameter> are adjusted accordingly so your own code will
never see those standard arguments.
</para>
@argc:
@argv:
<note>
<para>
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 <function>gtk_init_check</function>
instead.
</para>
</note>
@argc: Address of the <parameter>argc</parameter> parameter of your
<function>main</function> function. Changed if any arguments were
handled.
@argv: Address of the <parameter>argv</parameter> parameter of
<function>main</function>. Any parameters understood by <function>
gtk_init</function> are stripped before return.
<!-- ##### FUNCTION gtk_init_check ##### -->
<para>
This function does the same work as <function>gtk_init</function> with only
a single change: It does not terminate the program if the GUI can't be
initialized. Instead it returns %FALSE on failure.
</para>
<para>
This way the application can fall back to some other means of communication
with the user - for example a curses or command line interface.
</para>
@argc:
@argv:
@Returns:
@argc: A reference to the <parameter>argc</parameter> of the <function>main
</function> function.
@argv: A reference to the <parameter>argv</parameter> of the <function>main
</function> function.
@Returns: %TRUE if the GUI has been successful initialized,
%FALSE otherwise.
<!-- ##### FUNCTION gtk_exit ##### -->
<para>
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.
</para>
@error_code:
@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.
<!-- ##### FUNCTION gtk_events_pending ##### -->
<para>
Check if any events are pending. This can be used to update the GUI
and invoke timeouts etc. while doing some time intensive computation.
</para>
@Returns:
<example>
<title> Updating the GUI during a long computation</title>
<programlisting>
/* computation going on */
...
while (gtk_events_pending ())
gtk_main_iteration ();
...
/* computation continued */
</programlisting>
</example>
@Returns: %TRUE if any events are pending, %FALSE otherwise.
<!-- ##### FUNCTION gtk_main ##### -->
@ -115,18 +199,53 @@ General
<!-- ##### FUNCTION gtk_true ##### -->
<para>
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...
</para>
@Returns:
<example>
<title> A persistent window</title>
<programlisting>
##include &lt;gtk/gtk.h&gt;
int
main (int argc, char **argv)
{
GtkWidget *win, *but;
gtk_init( &amp;argc, &amp;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;
}
</programlisting>
</example>
@Returns: %TRUE
<!-- ##### FUNCTION gtk_false ##### -->
<para>
Analogical to <function>gtk_true</function> this function does nothing
but always returns %FALSE.
</para>
@Returns:
@Returns: %FALSE
<!-- ##### FUNCTION gtk_grab_add ##### -->