Hi,
Shiraz Baig <[EMAIL PROTECTED]> writes:
> I am a newbie. Can anyone tell me, in the following
> elementary program, why doesn't the function "hello"
> that it has not been passed any data. Because in
> gtk-signal-connect, we are passing NULL data.
> Wherefrom is this data coming. In another case, I have
> seen drawing_area being passed like this. How does it
> get to the function "hello".
what was the question again? The code you posted looks
OK and I can't see what your question is. data as passed
to the function hello should indeed be NULL.
If you have seen a drawing_area pointer in a signal
callback where you expected your user_data you most
probably connected a callback with a wrong signature.
Not all signals are declared as the clicked signal
of a GtkButton:
void (* clicked) (GtkButton *button);
which expects a callback of the form
void callback (GtkButton *button,
gpointer data);
The signal "expose_event" of a GtkWidget for
example is defined as
gint (* expose_event) (GtkWidget *widget,
GdkEventExpose *event);
so you need to use a callback of the form
gint callback (GtkWidget *widget,
GdkEventExpose *event,
gpointer data);
Or you'd get the event pointer instead of the expected
user_data.
Salut, Sven
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