Multi{pointer,touch} & Userspace

[Jim Gettys]

As far as it goes, yes; but there are other properties of touch sensors
that page does not cover: e.g. pressure, and potentially angles.

Some touch sensors give in you in effect images, with pressure on a per
pixel basis, rather than a simple binary "yes/no" and regions.  One
sensor I've seen literally gives you a grayscale image, and you can
"see" the out of focus hand in lighter shades of gray as it gets further
from the surface.f

Ergo my interest in an extensible event format, into which additional
data can be put (and in which applications that don't understand this
additional data can easily and safely ignore that data).

Otherwise the deployment of additional new sensor types will be limited
by the deployment of software on both sides of the client/server split;
experience shows that this is *very* hard to arrange.  Being able to
deploy client application and the X support required for it
independently (as was done with Xft) is key to a successful deployment
strategy.
                          - Jim


On Sat, 2008-11-01 at 10:55 +0100, Florian Echtler wrote:
> > > Known to be unbelievable overkill, yes.  Not to mention that you cannot
> > > do parsing of anything other than a full document, so a single pointer
> > > movement blows out to:
> > .... long verbose xml elided....
> > My motivation is that touch devices can provide much more complex data
> > than devices we've had to deal with in the past (up to and including
> > full images), that may need multiple levels of interpretation (depending
> > on the sophistication of the targeted application).
> Please allow me to steer the conversation back to the original topic. As
> mentioned before, the question whether the format is XML or not is
> basically just one of which iostream class you use..
> 
> My original intention in posting all of this was rather to ask if the
> _concepts_ described here [1] make sense to you from a window-system
> viewpoint.
> 
> [1] http://tisch.wiki.sourceforge.net/EventProtocol
> 
> Thanks, Yours, Florian
-- 
Jim Gettys <jg at laptop.org>
One Laptop Per Child