Re: passing on signals

[Sven Neumann]

Hi,

edscott wilson garcia <[EMAIL PROTECTED]> writes:

> I suppose the additional parameter after event will make the call
> blocking so that the return value of the signal handler can be
> returned there, and if there is no additional parameter (or set to
> NULL) the function will just toss the signal on to the queue to be
> processed by the event loop and be non-blocking. Just a
> hypothesis...

Wrong again. GObject signals are always executed synchronously. The
g_signal_emit() call returns when all signal handlers have been run.
If you pass extra parameters to the g_signal_emit() call you don't
change anything.


Sven
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Re: passing on signals

[edscott wilson garcia]

Thanks for the clarification, Sven. 

I suppose the additional parameter after event will make the call
blocking so that the return value of the signal handler can be returned
there, and if there is no additional parameter (or set to NULL) the
function will just toss the signal on to the queue to be processed by
the event loop and be non-blocking. Just a hypothesis...

On Thu, 2003-10-02 at 14:04, Sven Neumann wrote:
> Hi,
> 
> edscott wilson garcia <[EMAIL PROTECTED]> writes:
> 
> >   Does anybody know the correct way to pass on keypressed signals
> > received by one widget to another? Either of the following two lines
> > causes gtk to segfault when signal received by GtkCombo is passed to
> > GtkEntry:
> > 
> > gtk_signal_emit_by_name (GTK_OBJECT (entry),
> > "key_press_event",event,data,NULL);
> > 
> > gtk_signal_emit_by_name (GTK_OBJECT (entry),
> > "key_press_event",event,data);
> 
> Both lines are wrong. The user_data that is passed to a signal
> callback is not set on signal emission but it's the data set when the
> signal was connected. The correct code would be:
> 
>  gtk_signal_emit_by_name (GTK_OBJECT (entry), "key_press_event", event);
> 
> Actually this is deprecated API, so you would better use the following
> instead:
> 
>  g_signal_emit_by_name (entry, "key_press_event", event);
> 
> This code assumes that event is a pointer to a GdkEventKey structure.
> 
> 
> Sven
> 

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Re: passing on signals

[Sven Neumann]

Hi,

edscott wilson garcia <[EMAIL PROTECTED]> writes:

>   Does anybody know the correct way to pass on keypressed signals
> received by one widget to another? Either of the following two lines
> causes gtk to segfault when signal received by GtkCombo is passed to
> GtkEntry:
> 
> gtk_signal_emit_by_name (GTK_OBJECT (entry),
> "key_press_event",event,data,NULL);
> 
> gtk_signal_emit_by_name (GTK_OBJECT (entry),
> "key_press_event",event,data);

Both lines are wrong. The user_data that is passed to a signal
callback is not set on signal emission but it's the data set when the
signal was connected. The correct code would be:

 gtk_signal_emit_by_name (GTK_OBJECT (entry), "key_press_event", event);

Actually this is deprecated API, so you would better use the following
instead:

 g_signal_emit_by_name (entry, "key_press_event", event);

This code assumes that event is a pointer to a GdkEventKey structure.


Sven
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Re: passing on signals

[edscott wilson garcia]

On Tue, 2003-09-30 at 20:09, edscott wilson garcia wrote:
> Hi,
> 
>   Does anybody know the correct way to pass on keypressed signals
> received by one widget to another? Either of the following two lines
> causes gtk to segfault when signal received by GtkCombo is passed to
> GtkEntry:
> 
> gtk_signal_emit_by_name (GTK_OBJECT (entry),
> "key_press_event",event,data,NULL);
> 
> gtk_signal_emit_by_name (GTK_OBJECT (entry),
> "key_press_event",event,data);


If anyone is interested, I figured this one out:
gtk_signal_emit_by_name() is blocking, i.e. it does not return until the
signal has been duly received and processed by the target widget's
signal handler. And the value of "data" is overwritten by the return of
the signal handler (in this case it returns a guint).

This means that you must save whatever you have in "data" to restore it
after the function returns. But the fact that gtk_signal_emit_by_name()
is blocking means that you have to get into the thread business if you
want to make things work as with signal queue. So you are much better
off calling the signal handler of the signalled widget directly. Oh
well...

Edscott

> 
> 
> TIA,
> 
> Edscott Wilson Garcia
> 
> 
> 
> 
> 
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passing on signals

[edscott wilson garcia]

Hi,

  Does anybody know the correct way to pass on keypressed signals
received by one widget to another? Either of the following two lines
causes gtk to segfault when signal received by GtkCombo is passed to
GtkEntry:

gtk_signal_emit_by_name (GTK_OBJECT (entry),
"key_press_event",event,data,NULL);

gtk_signal_emit_by_name (GTK_OBJECT (entry),
"key_press_event",event,data);


TIA,

Edscott Wilson Garcia





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