[PATCH inputproto 2/2] Document smooth-scrolling support

[Daniel Stone]

Hi,

On Fri, Jun 24, 2011 at 08:18:27AM +1000, Peter Hutterer wrote:
> On Thu, Jun 23, 2011 at 10:50:41AM +0100, Daniel Stone wrote:
> > On Thu, Jun 23, 2011 at 10:44:44AM +1000, Peter Hutterer wrote:
> > > one more question:
> > > What do we do for backwards compatibility? 2.0 clients get both events?
> > > 2.0 clients won't see the flag after all and would be lead to think that
> > > there's movement _and_ scrolling.
> > 
> > A 2.0 client which listens for 2.1 axes but doesn't pay attention to 2.1
> > flags? I think we can just put that one in the 'well, don't do that'
> > basket, to be honest.
> 
> you can't choose which axes you listen to, you get all of them. with smooth
> scrolling, a 1.x/2.0 client (built before the addition of the scrolling
> labels) would see motion events on two unknown/unlabelled axes and button
> 4-7
> events.
> 
> Now, of course there's the argument that you shouldn't be handling axes that
> you don't know what they are but that doesn't help 1.x clients at all (plus,
> we have e.g. in the wacom driver several axes that are still "unknown").

I don't think we can really support clients which just take axes they
have no idea about and do any random crap with them.  It would be fairly
easy to not send smooth-scrolling events to pre-2.1 clients, mind.

Cheers,
Daniel