[PATCH v5 wayland] protocol: add wl_pointer.frame, axis_source, axis_stop, and axis_discrete

[Bill Spitzak]

On Wed, Nov 18, 2015 at 2:46 PM, Peter Hutterer <peter.hutterer at who-t.net>
wrote:

> On Mon, Nov 16, 2015 at 07:07:46PM +0000, Daniel Stone wrote:
> > Hi,
> >
> > On Monday, 16 November 2015, Bill Spitzak <spitzak at gmail.com> wrote:
> > >
> > > Since the "frame" event groups everything together, it does not seem
> like
> > > there is a need to talk about "latching". _descrete events are
> "latching"
> > > in that they are in the same frame. This could remove some complexity
> from
> > > your description I think.
> > >
> >
> > Indeed, talking about grouped rather than latched events may help a bit.
> We
> > already use latched to describe, e.g. wl_surface.commit, and using
> > different language may help clarify a bit.
>
> discrete events are latching for axis events though, they're not just
> grouped in the same frame, they always precede the axis event. If you have
> two axis updates in the same frame, the only allowed order is:
>     axis_discrete
>     axis
>     axis_discrete
>     axis
>     frame
>
> it is not permitted to have:
>     axis_discrete
>     axis_discrete
>     axis
>     axis
>     frame
>
> Theoretically possible now that we carry the axis information, but that'd
> require buy-in from all the current reviewers.
>

I think you might want to check to see if everybody thinks that is ok,
because it makes things simpler by only having to talk about frames, and
removing the latching discussion. I think what is happening is that wayland
is starting to group events and requests, and is settling on an idea of a
frame message to delimit the groups, rather than the latching idea.

The Weston code can still always send them in the alternating order, with a
comment in the code that this is for back-compatibility, but removing any
discussion of latching from the documentation.
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