Re: variables in g_signal_connect

[Christopher Anderson <sidewinder asu gmail com>]

You should use the GINT_TO_POINTER() macro on your variable. Then use
GPOINTER_TO_INT() to extract the int back out of the pointer.

 See this: http://developer.gnome.org/doc/API/2.0/glib/glib-Type-Conversion-Macros.html#GINT-TO-POINTER:CAPS

This method will work, but only for integers (since pointers are
really just integers that store a memory address). If you want to pass
other variable types (or even multiple variables), just create a
struct with everything you need, make a pointer that points to it, and
pass that to your signal handler.

Cheers,
Chris Anderson


On 7/14/05, Michal Porzuczek <mporzuczek gmail com> wrote:
> When connecting signals to methods is is possible to add additional
> variables to the signals and if so in which way. Furthermore, the 4th
> variable, data, does it have to be a gpointer?
>
> I have the following function defined as:
>
> Horizontal_Zoom_In_clicked(GtkWidget *widget, int gt)
>
> and the signal connection as:
>
> g_signal_connect ((gpointer) Horizontal_Zoom_In, "clicked",
>                                   G_CALLBACK (Horizontal_Zoom_In_clicked),
>                                   graph_type);
>
> where graph_type is an int. as a result I get a
> warning: passing argument 4 of 'g_signal_connect_data' makes pointer
> from integer without a cast
>
> now I was wondering if it is possible to pass a variable into the
> Horizontal_Zoom_In_clicked method without it being a gpointer but an
> int instead and if so how this is to be done.
>
> Thanks a lot,
>
> Michal
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