On Mon, Jan 9, 2012 at 7:22 AM, Chris Bagwell <ch...@cnpbagwell.com> wrote:
>
> I'd like to understand this better if ya don't mind.
>
> First up, is this usecase for absolute or relative mode?
Very good question ;-). To be honest, I didn't think about that when I
worked on it. It was for touchscreen devices. So, I assumed absolute mode.
But, from the code, it is clear that I have not taken care of that...
> I'll phrase it like that instead of touchscreen/touchpad since some people
> put
> touchpad in absolute mode. Also, are gestures enabled or disabled?
I would suggest that wcmMT only applies to absolute mode unless you see if
differently. Under this assumption, gestures will have no meaning.
> For relative mode, Alexey just submitted a nice bug fix that may fix
> what your really worried about. Previously, during
> gestures-with-no-movement we were not storing updated X/Y movement so
> when you released gesture you'd get a big jump. I believe this was
> seen mostly during transition from 2 fingers to 1 finger (the case
> your talking about).
The issue is not with gestures. It is the "raw" ST value we get from the
kernel that is jumpy.
> Maybe you should try today's git and see if the issue is reproducible any
> more.
Will try, but not for this issue I think.
> Now on the ST vs. MT part. xf86-input-wacom doesn't know ST vs. MT.
> Its always MT to it. Sometimes its a MT with a count of 1 but still
> MT. So if we are seeing unwanted jumps during touch transitions, I'd
> like to understand that better because I think there are real
> xf86-input-wacom bugs to fix beyond giving an optional disable.
>
As mentioned above, the jump was "raw", we can not use the ST events
reported from the kernel as is when there are more than one finger on the
tablet.
> I'm actually a little surprised that ignoring MT events and looking at
> only ST events helps instead of hurts. At least in
> xf86-input-synatpics, there is special logic to detect transition of
> fingers and to account for an expected cursor jump in ST values.
How did that work?
> Probably, for wacom it depends on finger release order. If you
> release 1st finger before 2nd finger then you should see a nice cursor
> jump since finger tracking is forced to move to only remaining finger.
>
You are right. I think that is the root cause of the jump, which I do not
have a way to correct, and ST app users do not like.
Ping
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