Re: [Qemu-devel] paravirtual mouse/tablet

[Gerd Hoffmann <kraxel@redhat.com>]

   Hi,

>> I guess a mere tuple of (x,y,down) N times should be enough for the
>> protocol, no?
>
> Surely, evdev has an interface to support this already. Let's just do
> what it does instead of inventing something that none of us can validate
> actually works.

http://www.mjmwired.net/kernel/Documentation/input/multi-touch-protocol.txt

Looks like the linux input layer does effectively the same: send series 
of events for multitouch.

A sync event to mark the end of the batch is obviously a pretty good 
idea I'm going to steal.

Some devices seem to be able to attach IDs to the touchpoints.  Then you 
don't have to send the whole set each time but can limit yourself to the 
ones which did actually change.  We should support that too.

> Or better yet, delay implementing it until someone actually knows how to
> support it.

I think we can get sane support into the protocol right from start, and 
that is much better than adding something afterwards.  Just look at the 
linux input layer document -- some of the loops they have to hop though 
are there just because multitouch is a extension which came later.

cheers,
   Gerd