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-- This example shows how you can connect a handler that returns a value to
-- a widget.
-- The example chosen is "delete_event", that returns either True or False,
-- depending on whether we should allow the window to be closed by the window
-- manager or not.
with Gtk.Main;
with Gtk.Rc;
with Gtk.Handlers;
with Gdk.Event; use Gdk.Event;
with Gtk.Enums; use Gtk.Enums;
with Gtk.Button; use Gtk.Button;
with Gtk.Window; use Gtk.Window;
with Ada.Text_IO; use Ada.Text_IO;
procedure Delete_Event is
-------------
-- Deleted --
-------------
function Deleted (B : access Gtk_Window_Record'Class;
Event : Gdk_Event)
return Boolean
is
pragma Unreferenced (Event);
pragma Unreferenced (B);
begin
-- If you return FALSE in the "delete_event" signal handler,
-- GTK will emit the "destroy" signal. Returning TRUE means
-- you don't want the window to be destroyed.
-- This is useful for popping up 'are you sure you want to quit?'
-- type dialogs.
Put_Line ("You can not close the window like that...");
return True;
end Deleted;
------------
-- Delete --
------------
procedure Delete (B : access Gtk_Button_Record'Class;
To_Be_Deleted : Gtk_Window) is
pragma Unreferenced (B);
begin
Put_Line ("Quit the application and destroy the window.");
Destroy (To_Be_Deleted);
Gtk.Main.Main_Quit;
end Delete;
package Button_Cb is new Gtk.Handlers.User_Callback
(Gtk_Button_Record, Gtk_Window);
package Event_Cb is new Gtk.Handlers.Return_Callback
(Gtk_Window_Record, Boolean);
Win : Gtk_Window;
B : Gtk_Button;
begin
Gtk.Main.Set_Locale;
Gtk.Main.Init;
Gtk.Rc.Parse ("testgtkrc");
Gtk_New (Win, Window_Toplevel);
Event_Cb.Connect (Win, "delete_event",
Event_Cb.To_Marshaller (Deleted'Access));
Gtk_New (B, "Close");
Add (Win, B);
Button_Cb.Connect (B, "clicked",
Button_Cb.To_Marshaller (Delete'Access), Win);
Show_All (Win);
Put_Line ("Not that you can't simply close the window by clicking on the"
& " icon at the top");
Put_Line ("You have to explicitly press the Close button to quit the"
& " application.");
Put_Line ("This is implemented through a handler for the delete_event"
& " callback.");
Gtk.Main.Main;
end Delete_Event;
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