On Wed, Oct 5, 2011 at 1:22 AM, Alexia Death <alexiade...@gmail.com> wrote:
> On Wed, Oct 5, 2011 at 4:00 AM, Jason Gerecke <killert...@gmail.com> wrote:
>> For the X driver, we run into a backwards-compatibility problem
>> (...unless we go the lame route with ABS_WHEEL). While XI2 provides up
>> to 36 valuators, I believe there was a limit of 6 valuators at some
>> point in the past. With the pad device having 3 axes reserved for
>> X/Y/P, and 2 axes reserved for touch strips, there's just not enough
>> room for both touch rings. We can break apps that were written with
>> the 6 valuator limit in mind or break apps that assume the first 5
>> axes are X/Y/P/TSl/TSr. I'm not sure what kind of fall-out to expect
>> from either option, so any insight would be appreciated :)
>
> From my cursory look at GDK code long ago having more valuators is
> unlikely to break anything. They just wont be used/supported until
> software gets updated. Breaking the assumptions about the first five
> however is most likely to cause six kinds of havoc.
>
> --
> --Alexia
>

Continuing to throw out ideas, if we can turn the touchstrip into
keys/buttons, that opens up a sub-category of the second option:
placing the touch ring data into the touch strip valuators. While this
still has the possibility of breaking things, the fallout should be
minimal given how similar the two are to each other. Applications
which use the touch strip as a relative axis should be completely
unaffected, while those that use it as an absolute axis will be usable
with the caveat that 0% and 100% will be more difficult targets to
achieve (due to the touch rings' increased resolution). This has the
benefit of allowing applications to use both rings without needing to
be rewritten to support XI2, and since the semantic meaning of the
axes are (very nearly) preserved there is little chance of the change
causing problems.

I'll try adding a 7th valuator to the X driver to see if there are any
obvious breaks that result. I'd also like to hunt down the code in GTK
that reads in the valuators from X, but that'll probably take me a
while...

Jason

---
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