[PATCH wayland-protocols v2] unstable: Add input-timestamps protocol

[Alexandros Frantzis]

On Tue, Dec 19, 2017 at 10:15:06AM +0200, Pekka Paalanen wrote:
> On Mon, 18 Dec 2017 14:55:00 +0200
> Alexandros Frantzis <alexandros.frantzis at collabora.com> wrote:
> 
> > wl_pointer, wl_keyboard and wl_touch events currently use a 32-bit
> > timestamp with millisecond resolution. In some cases, notably latency
> > measurements, this resolution is too coarse to be useful.
> > 
> > This protocol provides additional high-resolution timestamps events,
> > which are emitted before the corresponding input event. Each timestamp
> > event contains a high-resolution, and ideally higher-accuracy, version
> > of the 'time' argument of the first subsequent supported input event.
> > 
> > Clients that care about high-resolution timestamps just need to keep
> > track of the last timestamp event they receive and associate it with the
> > next supported input event that arrives.
> > 
> > Signed-off-by: Alexandros Frantzis <alexandros.frantzis at collabora.com>
> > Reviewed-by: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
> > Acked-by: Jonas Ådahl <jadahl at gmail.com>
> > ---
> > 
> > Changes in v2:
> >  - Add '...carrying a timestamp...' to better describe the set of subsequent
> >    input events in the timestamp event description. 
> >  - Clarify normalization requirements of tv_sec_hi, tv_sec_lo, tv_nsec
> >    timestamp representation.
> > 
> >  Makefile.am                                        |   1 +
> >  unstable/input-timestamps/README                   |   4 +
> >  .../input-timestamps-unstable-v1.xml               | 145 +++++++++++++++++++++
> >  3 files changed, 150 insertions(+)
> >  create mode 100644 unstable/input-timestamps/README
> >  create mode 100644 unstable/input-timestamps/input-timestamps-unstable-v1.xml
> 
> Cool! I suppose we want to see the Weston implementation patches posted
> to the list before landing this?

The plan is to refresh and clean up the proof-of-concept Weston
implementation and propose it. For those interested to take an
early look the p-o-c code is at:

https://gitlab.collabora.com/alf/weston/commits/zwp-input-timestamps

> Alf, what would you have for the client side of the implementation?

The weston p-o-c implementation branch includes tests that I think
exhibit well the client side use of this protocol, but if that's not
sufficient I am happy to add or enhance an example client to use this
protocol.

Thanks,
Alexandros