On Sun, 2009-01-11 at 19:37 -0800, Matt Helsley wrote:
> Currently X, Y, and PRESSURE are special case axes in xf86-input-evdev.
> This patch supports axes in a more general way. There are a few open
> questions and TODOs:
>
> TODO:
> Add REL axes. Since we currently limit evdev devices to
> exclusively REL or ABS axes we can reuse the same vals
> buffer in the device structure.
>
> In theory there can be more than MAX_VALUATORS axes. Often there
> will be less than MAX_VALUATORS axes. This either fails
> to fully support a device or wastes a space. Should
> probably switch to dynamically-allocated values but this
> means we need an UnInit function.
>
> Needs testing. Currently I've only got devices that
> support up to three axes. A nice Wacom tablet that
> supports tilt might be able to test more axes with
> some small testing-specific kernel/X driver hacks.
> Any other ideas for testing?
>
> I'd like to move EvdevCacheCompare() above EvdevProbe() -- it
> means we can get rid of all but the GRAB ioctls() from
> EvdevProbe().
>
> Put back the button-as-ABS_PRESSURE test.
>
> QUESTIONS:
> Is this the only code that needs to test and count bits or can
> we make these pieces common somehow?
>
> There are still locations that special-case X and Y:
I forgot to finish the question here. Should we leave these as special
cases?
> 1. TOUCHPAD dx, dy calculation
> 2. Axis-swapping (would require an axis-mapping)
> 3. Axis-inversion
> 4. Calibration
<snip>
> The swap, scale, inversion, and calibration transforms look like
> they are done in the wrong order; we wind up using Y's
> min and max to invert X if we've swapped the axes. I'd
> think we'd want to swap later if not last...
And here: Am I just not thinking straight about these?
Does X have any layers to handle:
REL <-> ABS conversion (switch_mode?)
Axis inversion
Other valuator transforms (e.g. calibration?)
Axis mapping/swapping
in a more driver-agnostic way than using evdev-specific mechanisms? Also
I'd like to know how the calibration bits are meant to work. Can I get
any pointers to documentation/code on these parts?
Thanks!
Cheers,
-Matt Helsley
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