absolute coordinate mouse support

Adam Jackson ajax at nwnk.net
Wed Sep 21 12:16:51 PDT 2005

On Wednesday 21 September 2005 14:07, Alex Williamson wrote:
> On Wed, 2005-09-21 at 13:50 -0400, James Cloos wrote:
> > >>>>> "Alex" == Alex Williamson <alex.williamson at hp.com> writes:
> >
> > Alex> an tell me to switch to something besides the X "mouse" driver
> >
> > Perhaps evdev does what you want.
>    Yes, I was just looking into that, thanks for mentioning it.  The
> evdev driver apparently ignores absolute data at the moment, but I think
> I can add that without too much problem.  Probably missing just because
> absolute coordinate devices aren't nearly as common.

There's an open bug for some absolute pointer support in evdev, it's one of 
the blockers on #968 and I'd like to see it merged.

evdev (the kernel driver) will generate absolute pointer events for three 
kinds of devices: touchscreens, touchpads, and digital game pads.  They all 
have slightly different semantics.  Touchscreens should instantly warp the 
pointer to the pointed-to location.  Touchpads should interpolate drag motion 
into pointer motion.  Game pads should start polling on button-down and 
continue to generate motion events in that direction as long as the button 
stays down (since not all evdev devices will generate repeat events).

I haven't played with analog game pads under evdev, they might generate 
absolute motion events too.

Unfortunately I don't know any good way to detect what sort of device is being 
examined.  We could probably add a flag for this to the evdev protocol, but 
we'd still need an option to set this for older kernels.

- ajax
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