On Thu, 05 Nov 2020 07:35:04 +0000 Simon Ser <cont...@emersion.fr> wrote:
> Hi,
>
> On Thursday, November 5, 2020 3:26 AM, zou lan <nancy.lan....@gmail.com>
> wrote:
>
> > Hi pekka
> >
> > I want to ask if in one client have created many wl surfaces, and commit
> > all of them to weston in one frame, could weston guarantee to handle these
> > surface update commands in one repaint?
> >
> > The sample code may like this:
> > redraw() {
> > wl_surface_commit(surface1);
> > wl_surface_commit(surface2);
> > wl_display_dispatch();
> > }
> >
> > I think weston will handle the commit of surface1 and surface2 before next
> > repaint because surface1 and surface2 are belong to one client, is that
> > correct? Thank you!
>
> No, there's no such guarantee. The OS could pre-empt the client after
> the first wl_surface_commit is flushed on the wire and before the
> second one is. The request reads on the compositor side could also be
> split between these two requests. (This is still pretty unlikely, I
> think in practice you'll get the two surfaces updated at the same
> repaint "by chance" almost systematically.)
>
> There's a WIP protocol to allow to synchronize multiple surfaces [1].
>
> Simon
>
> [1]:
> https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/26
Indeed.
Also sub-surfaces can be synchronized with their parent, but that
doesn't help you if you need the surfaces to have other roles.
Thanks,
pq
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