Re: [Qemu-devel] [PATCH 4/4] gtk: add opengl support, using egl

[Max Reitz]

On 20.05.2015 16:14, Gerd Hoffmann wrote:
>    Hi,
>
> > I can't give any R-b, because that would require really digging into
> > Gtk... The code is pretty similar to the SDL code, though (not by
> > chance I guess),
> Indeed ;)
>
> >   so it looks fine to me. If it would compile, that is, see below.
> >
> > (It does work with Gtk 2, though)
> >
> > ((at least on my laptop with mesa; on my desktop with fglrx, creating
> > the shader fails, which may or may not have to do something with
> > "libEGL warning: DRI2: failed to authenticate" (which is probably in
> > turn my own fault for using a proprietary driver)))
> Could also be selinux.

Except I don't use SELinux (here). I know, I know, shame on me.

> > > +#if defined(CONFIG_OPENGL)
> > > +    if (display_opengl) {
> > > +        gtk_widget_set_double_buffered(vc->gfx.drawing_area, FALSE);
> > gcc said:
> > > qemu/ui/gtk.c:1742:9: Fehler: »gtk_widget_set_double_buffered« is
> > deprecated (declared at /usr/include/gtk-3.0/gtk/gtkwidget.h:896)
> > [-Werror=deprecated-declarations]
> Yep, that is a bit awkward.
>
> Deprecated because gtk_widget_set_double_buffered() doesn't work with
> the wayland backend.  The switch simply doesn't make sense with the
> wayland rendering pipeline, and the egl rendering might not work on
> wayland because of that (/me didn't try).

Right, but we cannot really tell gtk that we know what we're doing. :-)

> Nevertheless gtk_widget_set_double_buffered() is required to make gl
> rendering work (on X11 backend), for versions older than 3.16.  On 3.16+
> we can use the opengl support provided by gtk instead.  Code for that
> still needs to be written though.

Yep, that's what I thought of, too. But the problem is, as you yourself 
say, that 3.14 < 3.16...

Max

> > But then again it didn't compile before, either: qemu/ui/gtk.c:1927:5:
> > Fehler: »gdk_cursor_new« is deprecated (declared
> > at /usr/include/gtk-3.0/gdk/gdkcursor.h:223)
> > [-Werror=deprecated-declarations]
> Saw your patch for that, thanks.
>
> > gtk_widget_set_double_buffered() was deprecated in 3.14 already (as
> > far as I can see from the header file alone).
> They should have done that in 3.16 IMO ...
>
> cheers,
>    Gerd