From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: gtkada evenhandler on_procedure method , how to access children of topwindow in the eventhandler
Date: Sat, 2 Nov 2019 12:03:20 +0100
Date: 2019-11-02T12:03:20+01:00 [thread overview]
Message-ID: <qpjnpp$v9g$1@gioia.aioe.org> (raw)
In-Reply-To: cf3be50e-637f-4db3-b0a2-ed5d251af8b5@googlegroups.com
On 2019-11-02 11:22, Alain De Vos wrote:
> I have a window with obe button and one label and want to change the text on the label when the button is pressed in the eventhandler, I pass the top window.
>
> procedure hello is
> Top : Gtk.Window.Gtk_Window;
> Button : Gtk_Button;
> Label : Gtk_Label;
> VBox : Gtk_Box;
> procedure Create_Window is
> begin
> Gtk.Window.Gtk_New
> (Window => Top,
> The_Type => Gtk.Enums.Window_Toplevel);
> Gtk.Window.Set_Title (Window => Top, Title => "Hello from ADA");
> Gtk_New(Button);
> Button.On_Clicked (Call => On_Button_Click'Access,
> Slot => Top);
> Gtk_New(Label);
> Gtk_New_Vbox(VBox);
> Add (VBox,Button);
> Add (VBox,Label);
> Add (Top,VBox);
> Gtk.Window.Show_All (Top);
> end Create_Window;
> begin
> Gtk.Main.Init;
> Create_Window;
> Gtk.Main.Main;
> end hello;
>
> I pass the topwindow to the eventhandler(slot).
> In the eventhandler I need go from the Top to the Vbox to the Label and set the text on the label ... button pressed. I probably need to set a property in the main and query it in the handler and cast the correct type ...
> {The label is not directly visible in the handler ...}
>
> package body buttonhandler is
> procedure On_Button_Click (Top : access Glib.Object.GObject_Record'Class) is
> begin
> Put_line ("Hallo");
> -- I need to go from Top to Vbox to Label and set text ... ????
> end On_Button_Click;
> end buttonhandler;
It is possible to enumerate children of a container, but that is not the
recommended way as it is weakly typed and fragile. A better way is a
derived widget. It is very easy to drive customized widgets in GtkAda. E.g.
type My_Box_Record is new Gtk_VBox with -- Derive from VBox
Button : Gtk_Button;
Label : Gtk_Label;
end record;
type My_Box is access all My_Box_Record;
procedure Gtk_New (Box : out My_Box);
Creation:
procedure Gtk_New (Box : out My_Box) is
begin
Box := new My_Box_Record;
Initialize_Vbox (Box); -- Parent's initialization from Gtk_Box
Gtk_New (Box.Button);
Box.Add (Box.Button);
Gtk_New (Box.Label);
Box.Add (Box.Label);
-- Connect signal handlers here, pass My_Box to them
end Get_New;
Put declaration of the custom widget in a separate package. All handlers
go into the package body. [This will reduce the inevitable mess GTK
imposes on any otherwise cleanly designed Ada application]
--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
next prev parent reply other threads:[~2019-11-02 11:03 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-02 10:22 gtkada evenhandler on_procedure method , how to access children of topwindow in the eventhandler Alain De Vos
2019-11-02 11:00 ` Alain De Vos
2019-11-02 11:03 ` Dmitry A. Kazakov [this message]
2019-11-02 15:27 ` Alain De Vos
2019-11-02 16:18 ` Dmitry A. Kazakov
2019-11-02 19:07 ` Alain De Vos
2019-11-02 19:21 ` Dmitry A. Kazakov
2019-11-02 22:03 ` Alain De Vos
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