[Glade-users] Update progressbar from forked child

[steven at whoaa.be (Steven)]

Hi Tristan,

Thx for your answer.  I'll subscribe to the gtk lists.

I tried your solution, and it works half...

If I use vfork, my main window hangs until the child is done, and then
the progressbar is updated nicely
(but the function keeps running, despite the return FALSE;)
If I use fork, the main window doesn't hang but the idle_function isn't
executed (even not when the child exits)

Do you mind glancing an eye on my code ?  I'm not used to program GUIs
and work with events etc, so I guess it's a stupid mistake somewhere.
And I'll be glad if you could point it out :-)

Thx
Steven

================= CODE =================

void on_button6_released (GtkButton *button, gpointer user_data)
{
    blabla
    int pid=fork();
    if (pid == 0)
    {
        while (...)
        {
            int error_sig;
            progress = ((counter*PBfraction)+PBfraction);
            g_spawn_sync(NULL, argv, NULL, G_SPAWN_SEARCH_PATH, NULL,
NULL, NULL, NULL, &error_sig, NULL);
            g_idle_add(update_progressbar, &progress);

            counter++;
        }
        _exit(0);
    }
}

void update_progressbar (fraction)
{
    GtkWidget *progressbar = lookup_widget(GTK_WIDGET(main_widget),
"progressbar1");
    gtk_progress_bar_set_fraction(progressbar, .5);
printf("Function called, fraction : %f\n", fraction);
    return FALSE;
}

================= /CODE =================

Tristan Van Berkom wrote:
> Steven wrote:
> > Hi there,
> >
> > This is my first attempt to Gtk Programming in Glade. Although I know
> > php and a little VB, It's been a long time since I used ansi C and maybe
> > I'm doing stupid things.  Please feel free to point them out :-)
>
> Hi Steven,
>     First of all, you'll get a better suited audience for gtk+
> programming
> related questions on the gtk lists (gtk-app-devel-list at gnome.org). This
> list is more related to the glade tool & the glade files that the
> glade tool
> generates.
>
> What I sugest you do (and there are a few ways) is this:
>
>  - Create a thread that is responsable for the entire process of
>    converting the images - from this thread you will never call gtk+
>    functions that deal with widgets (or progressbars) in the main GUI
> thread.
>
>  - In the thread you will loop through all the filenames and do the
> following
>    for each file:
>      o call g_spawn_sync(/* program to convert one file */);
>      o call g_idle_add() /* to add a function that will be called from
> the
>        main thread the next time the main thread is idle */
>
>  - From the g_idle_add() callback that you registered from the worker
> thread
>    but runs in the main thread (the gtk_main() thread that is), you will
>    then proceed to call
> "gtk_progress_bar_whatever_you_want_cause_its_safe_here()"
>    and return FALSE to ensure the idle was a one shot deal for every
> time it
>    was explicitly registered from the thread.
>
> There you have it :)
>
> Cheers,
>                    -Tristan