Re: [Qemu-devel] [PATCH] [RFC] usb-wacom

["François Revol" <revol@free.fr>]

> The wacom-tablet was implemented to emulate a touchscreen originally,
> because Linux doesn't by default have drivers for any hotpluggable
> touchscreen. Reporting 0,0 when not touching allows the emulation to
> be used with tslib.  With a real tablet the stylus can also be too
> far
> above the surface for the coords to be avilable, but I don't know
> what
> coords are being reported then.

I don't either, but it actually depends on the model, and the
penpartner doesn't seem to repport if it's in range or not. See
hasContact variable in the Haiku driver is hardcoded for it. Which
means it should always send valid coords, likely the last known ones,
else the Haiku driver would also cause problems with real hardware, and
would have been fixed to cache.

> > Now, I'm not sure those max values are correct for all Penpartner
> > devices, or if they were calibrated on a specific item.
>
> I'm don't know either I'm afraid, for my use case it didn't matter
> because tslib will calibrate the input anyway.  It may be useful
> adding the correct HID descriptors (I though we already had them).

They are present in the generic usb-tablet emulation OTH.
I'll try to ask someone who knows about those values.

> > Finaly, I fixed button handling according to our driver, not sure
> > all
> > drivers handle them the same. pressure indicates left button, and a
> > flag tells about right one. I mapped middle button to the eraser to
> > at
> > least be useful in tablet-aware software though I'm not sure it's
> > the
> > best way.
>
> I'll check if this works with Linux also, when I get a chance. I
> didn't look at your patch yet as I'm away form my desktop

Thanks.

François.