Re: Update label immediately

[Rob Pearce <rob bdt-home demon co uk>]

On Sunday 20 July 2008, Johannes Bauer wrote:
> I'm writing an application which reads from a DMM (asynchronously, I'm
> using pthreads - is that a bad idea?)

Using threads is not bad in itself, but you must keep all GTK interaction in 
one thread. Basically, apart from a few Glib functions like g_idle_add, the 
library is not thread-safe, merely thread-aware.

> and displays the gathered data 
> graphically in a Gtk::DrawingArea and also updates the last value to a
> Gtk::Label. Events come in around every half second. The problem is, the
> label is not getting updated instantly, as I'd wish. Only when the mouse
> is moved over it, it apperas.
>
> The code that modifies the label is simple:
>
> label->set_label("foobar result");

I've done something similar except I use set_markup. This works fine, but I'm 
not using threads. The update is called from a g_io_channel callback, so it's 
handled by the Glib main loop.

What you probably need to do is make your DMM thread call g_idle_add when new 
data arrives, then do the GUI updates in the function you pass to that. That 
way the GUI stuff all lives in one Glib context.