program helloworld2; {$mode objfpc} {$H+} uses Glib2, Gdk2, Gtk2; (* Our new improved callback. The data passed to this function * is printed to stdout. *) procedure callback (widget : PGtkWidget; data : gpointer); cdecl; begin writeln ('Hello again - ', Pgchar (data), ' was pressed'); end; (* another callback *) function delete_event (widget: PGtkWidget; event : PGdkEvent; data : gpointer): gboolean; cdecl; begin gtk_main_quit; delete_event := FALSE; end; var window, button, box1 : PGtkWidget; (* GtkWidget is the storage type for widgets *) begin (* This is called in all GTK applications. Arguments are parsed * from the command line and are returned to the application. *) gtk_init (@argc, @argv); (* Create a new window *) window := gtk_window_new (GTK_WINDOW_TOPLEVEL); (* This is a new call, which just sets the title of our * new window to "Hello Buttons!" *) gtk_window_set_title (GTK_WINDOW (window), 'Hello Buttons!'); (* Here we just set a handler for delete_event that immediately * exits GTK. *) g_signal_connect (G_OBJECT (window), 'delete_event', G_CALLBACK (@delete_event), NULL); (* Sets the border width of the window. *) gtk_container_set_border_width (GTK_CONTAINER (window), 10); (* We create a box to pack widgets into. This is described in detail * in the "packing" section. The box is not really visible, it * is just used as a tool to arrange widgets. *) box1 := gtk_hbox_new (FALSE, 0); (* Put the box into the main window. *) gtk_container_add (GTK_CONTAINER (window), box1); (* Creates a new button with the label "Button 1". *) button := gtk_button_new_with_label ('Button 1'); (* Now when the button is clicked, we call the "callback" function * with a pointer to "button 1" as its argument *) g_signal_connect (G_OBJECT (button), 'clicked', G_CALLBACK (@callback), PChar('button 1')); (* Instead of gtk_container_add, we pack this button into the invisible * box, which has been packed into the window. *) gtk_box_pack_start (GTK_BOX(box1), button, TRUE, TRUE, 0); (* Always remember this step, this tells GTK that our preparation for * this button is complete, and it can now be displayed. *) gtk_widget_show (button); (* Do these same steps again to create a second button *) button := gtk_button_new_with_label ('Button 2'); (* Call the same callback function with a different argument, * passing a pointer to "button 2" instead. *) g_signal_connect (G_OBJECT (button), 'clicked', G_CALLBACK (@callback), PChar('button 2')); gtk_box_pack_start(GTK_BOX (box1), button, TRUE, TRUE, 0); (* The order in which we show the buttons is not really important, but I * recommend showing the window last, so it all pops up at once. *) gtk_widget_show (button); gtk_widget_show (box1); gtk_widget_show (window); (* Rest in gtk_main and wait for the fun to begin! *) gtk_main (); end.