Touchpad stylus mode

[Albert Cahalan]

On 3/17/07, Zephaniah E. Hull <warp at aehallh.com> wrote:
> On Sat, Mar 17, 2007 at 09:08:30PM -0400, Albert Cahalan wrote:
> > Bert Freudenberg and Jim Gettys had the right idea on March 7th.
> > It goes something like this:
> >
> > a. Mode switches do not move the pointer.
>
> Mode switches themselves do not move the pointer, however the only way
> to trigger a GS to PT switch is to put a stylus on the unit, immediately
> after switching to PT mode we get coordinate data for the stylus, which
> does cause the pointer to move.

So, from the user's view, mode switches DO move the pointer.
That is generally defective as a user interface.

BTW, I'd rather you didn't use "GS" and "PT", especially without
explaining them. I can deal with resistive/capacitive I think, if
I'm right that the middle thing is capacitive.

The stylus device is not shaped properly to cover the whole screen.
Distortion would be very bad. Cropping it would work OK, but would
waste 2/3 of the device. Unless you have some fantastic new idea,
the stylus device's screen mapping needs to be able to move.

Mode switches can be disorienting and surprising. There are a
number of things that can be done to deal with that:

Upon mode switch to stylus mode, one might draw an outline of
the stylus device on the screen.

Preventing sudden pointer movement on mode switch is critical.
To the raw stylus data, subtract the initial (post-mode-switch)
stylus data and add the pre-mode-switch screen location.