Re: [gtk-vnc-devel] [PATCH] Gtk-VNC not packed

[Anthony Liguori <anthony codemonkey ws>]

Richard W.M. Jones wrote:
> Anthony Liguori wrote:
> > Richard W.M. Jones wrote:
> > > Anthony Liguori wrote:
> > > > Richard W.M. Jones wrote:
> > > > > I don't know if you necessarily want to classify this as a bug, 
> > > > > but currently if you create a Gtk-VNC widget but don't pack it, 
> > > > > then it will segfault when it tries to draw anything.
> > > >
> > > > I'm not sure what "packed" is.  Do we need to wait for realize or 
> > > > something?  My concern with this patch is that the buffer 
> > > > disappears until the next resize so when things to get "packed" we 
> > > > don't start displaying like we should.
> > >
> > > Sorry, I wasn't clear.  This is when you create a Gtk-VNC widget but 
> > > don't add it to any container, but then you do make it connect to a 
> > > VNC server.  The widget segfaults, because the return value from
> > >
> > >   gdk_drawable_get_visual (GTK_WIDGET(obj)->window)
> > >
> > > is NULL, and you get a segfault a couple of lines later when visual 
> > > is dereferenced.
> > >
> > > This shouldn't affect any code which does pack the widget in a 
> > > container (visual != NULL).
> >
> > Yes, but that's not my concern.  My concern is if you connect a 
> > widget before packing it, and then wait a while before actually 
> > packing it.  When you pack it, you need to make sure it's displaying 
> > stuff.
> >
> > This is why I suggested listening for the realized signal.  I think 
> > this is the thing that indicates that a visual is now valid.
>
> If I understand you correctly, do you mean waiting for the realized 
> signal before starting up the coroutine?

No.  Your patch basically skips the on_resize() callback if visual != 
NULL.  on_resize() fills out the local framebuffer and sets it so that 
gvnc renders to it and expose has something to draw.

You can keep the visual != NULL check, but you would need to add a 
realized signal handler that then does the equivalent work of 
on_resize().  Otherwise, if you add a gtk-vnc widget *after* on_resize() 
gets called, you'll get a blank screen until the server sends a resize 
event.  By adding a signal handler, you fix that bug.

Regards,

Anthony Liguori

> Rich.