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SubjectRe: RFC: A generic pointer protocol

On Fri, 15 Nov 1996 wrote:

> This message concerns issues raised by Kenneth Albanowski and Albert
> Cahalan, and Mark Cooke as well.


> Hmmm... I'm doubtful. I'm currently adding a z-is-pressure flag,
> but I don't like using the buttons as pressure indication.

Consider it as a simplification for a drawing program. By having a
guaranteed pressure field, they don't have to worry about processing
special flags from the record. x, y, buttons, and pressure would always
give satisfactory results, regardless of what device is being used.
Plugging 255 (or whatever the max is) into the pressure field when any
button is pressed on a mouse is dead simple, and would make things much
simpler for programs.

> I plan to have my Wacom tablet working within tomorrow, so I can test
> things out. Unfortunately, I've no program sensitive to
> absolute-pointing devices in addition to text mode selection :)

Maybe different pressures should select different amounts of text? Light
touch is character, heavy touch is line? (Or should that be reversed...)

> The basic point here is that usually such drawing software uses
> a different pointer from the generic pointing device. You have
> the mouse *and* the tablet. I have to think about supporting
> multiple pointing devices -- it's not supported by now.

This starts to get messy, but should be dealt with properly. I think for
right now the proper solution is to keep the absolute and relative devices
separate, so that if a program requests both, they'll get the separate
pieces of hardware.

If more then one relative device is connected, there should be some way
for programs to pull out separate data streams, but a default
consolidated (summed) stream would be most appropriate. There isn't any
useful way to sum absolute devices, though.

> Well, I've never seen such software, but things should go well


Any decent CAD program will have a "tracing" mode that essentially uses
the tablet coordinates directly as drawing coordinates without any scaling

> It's already there. /dev/kpointer has it already applied, /dev/rpointer
> no (it's raw). The operations should be centralized as absolute
> devices don't have ballistics.


Kenneth Albanowski (, CIS: 70705,126)

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