Playing with touch screen events

Andy Green andy at
Mon Oct 20 14:51:53 CEST 2008

Hash: SHA1

Somebody in the thread at some point said:
| On Mon, 20 Oct 2008 18:00:36 +0800 Tick Chen <tick at> babbled:
| yup. most of these i have observed just in doing the ui stuff. drags are
| basically unreliabel as u get discontinuous events (down, move, move,
move, up,
| down, move, up, down, move, move, move, up) etc. if you press very
hard its
| reliable. and the offcenter press is another problem. you would
hope/think the
| press is in the middle of your finger, but its actually just at the very
| top/bottom or just off it above/below.
| what we need is a better touchscreen.. or a very very good filter
between the ts
| device and x events so every app gets reliable events. tslib i think
has such
| an infrastructure - BUT i never got time to play with it. :)

I think these behaviours can also be trouble in the driver... "pen up
and down" is a separate interrupt than sample from ADC and it wouldn't
surprise me if we can improve it.  There was a patch about it from Dima
Kogan recently;a=commitdiff;h=eff39cde0d3cdd2afd5e1b4be5a8eb6cf195543e

| nb - kinetic scrolling. inside e it actually collects a whole series
of events
| (the 20 most recent mouse events) and computes motion over all of them
(as long

Actual position averaging is pretty solved by the "median" patch stuff,
there's some question about whether it's acceptable upstream I guess we
are going to have to find out about.;a=commitdiff;h=e007095586274313f7d469040ddd1c469a20165c

|> I wrote a small application to observe the touch screen events.
|> And found some very interesting phenomenons.
|> 1. If the touch pressure is very light, the status of mouse will
|> becomes very unstable. Mistake move events as up and down events.

You did a good thing studying this Tick.

- -Andy

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