Re: gtk_signal_connect() and passing parameters

[Darin Adler <darin bentspoon com>]

On Tuesday, May 15, 2001, at 05:22  PM, Mazur Przemyslaw wrote:

> I'm having trouble passing any kind of parameters to
> my call back functions.  For example:
>
> int i = 1456;
> ...
> gtk_signal_connect(GTK_OBJECT(button1),
> "button_press_event",
> GTK_SIGNAL_FUNC(button1_callback), (gpointer) &i);
> ...
> void button1_callback(GtkWidget *widget, gpointer
> data)
> {
>   g_print("i: %d\n", *((int *)data));
> }
>
> Quite simply, I expect to see g_print() print 1456 as
> the value of i.  It does not.  Instead, it prints 4.
> Even more strange, if I double click on the button
> (which is a checkbox button), it prints 5 instead.

There are two problems with the code you posted here:

	1) The button_press_event signal has an additional parameter that you 
are not including in the declaration of your callback function.
	2) It looks like you are passing in the pointer to a local variable 
(i).

I think that problem #1 is what's tripping you up. Change your callback to:

        void button1_callback(GtkWidget *widget,
                GdkEventButton *button,
                gpointer data)
        {
                g_print("i: %d\n", *((int *)data));
        }

If i is a local variable, you have a separate problem.

    -- Darin