On Wed, Jul 12, 2000 at 11:15:57AM -0700, Jim Gettys wrote:
>
> >
> > -- Some digitizers have non-linear input systems and need input munging
> > beyond the simple device-independant translation/rotation/deskew that
> > calibration can provide. Most devices work fine with the equivalent
> > of a single affine transform at most, but I know of at least one
> > shipping touchscreen PDA/phone in Japan that essentially requires a
> > system of linear equations to normalize coordinates, and also has
> > two "dead zones" that must be worked around.
>
> Question: is a single affine transform going to get more than 90% of the
> devices out there? If so, lets run with this, and be done with it; leave
> the others to suffer for their own sins of bad hardware...
>
(sorry for the delay; I'm pretty burst with mailing list mail)
I don't know with how much hardware an affine transform will work;
I'm not really a digitizer expert, I've just worked with a number
of specific components. It certainly seems reasonable to say "the
kernel driver will normalize the coordinates if it's easy to do so,
otherwise it'll somehow convey the device type to userspace, and
it's the job of userspace to deal with weirdo hardware."
miket
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