----- Original Message -----
From: "Jim Gettys" <[EMAIL PROTECTED]>
To: "Mike Touloumtzis" <[EMAIL PROTECTED]>
Cc: "Charlie Flynn" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>;
<[EMAIL PROTECTED]>
Sent: Wednesday, July 12, 2000 2:15 PM
Subject: Re: [Handhelds] Re: Touch Screen Driver Generic Interface for all
Linux SA11x0 platforms.
> > A driver API should be clear about whether it normalizes coordinates
> > (in which case it must be possible to feed it calibration points from
> > a userspace app) or whether it passes raw digitizer input to higher
> > layers (in which case those layers must have hardware-dependent
> > code--this is the gpm approach).
> >
>
> I believe it is important that things be "sane" when you power up a
system.
> To me, this means that I need to be told somehow how to convert hardware
> device coordinates to something that applications (read X) can use.
>
> This argues to me to report the raw coordinates to user space, along with
> calibration data (which can be approximate when first started, but then
> updated with correct values if the user recalibrates the device).
/etc/pointercal
> Since you might (or might not) run a calibration application under a
window
> system, I think there should be a way to set the default calibration
> information in the driver, rather than have to recalibrate for each
> application that comes along. In some sense, this is rediculous (since
> all the calls would be doing is saving information for later), but the
> practical impact is large. Saving the information between processes is
> non-trivial...
echo ... > /etc/pointercal
Regards,
Brad
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