[Bug 1194] Touchscreen Jitter

bugzilla-daemon at bugzilla.openmoko.org bugzilla-daemon at bugzilla.openmoko.org
Tue Feb 5 01:48:35 CET 2008


------- Additional Comments From cwixon at usa.net  2008-02-05 01:48 -------
The file /etc/ts.conf contains exactly the same parameters and values on my Neo.
 And a quick browse through the tslib source suggests that the dejitter plugin
isn't very tunable -- that "delta" figure is only used to temporarily stop
dejittering when quick stylus movement is detected.

Dejitter performs a smoothing function by taking a weighted average of the four
most recent samples, and unless that "delta" square-of-distance threshold is
crossed between successive samples, outputs the smoothed value.

I'm thinking that this four-sample smoothing might not be aggressive enough for
our hardware -- I think we could benefit from even more smoothing plus some
hysteresis, for example.  Maybe I'll cobble together some attempts at this, if I
have time over the next week or so.

It will be interesting to see -- I haven't looked -- how bad the tslib data are
when using a finger rather than stylus.  Quite ugly, I suspect.

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