[PATCH libinput v9 0/2] add orientation, size and pressure of touch

[Andreas Pokorny]

Hi,

On Tue, Nov 24, 2015 at 1:41 AM, Peter Hutterer <peter.hutterer at who-t.net>
wrote:

> On Mon, Nov 23, 2015 at 07:58:28PM +0100, Andreas Pokorny wrote:
> [...]
> > measured values on the e4.5 jumped a lot further. I need a more accurate
> > method for that. In the second round I will probably try to verify the
> > result with a finger-paint application.
>
> that does not fill me with confidence. we can't expose an API where we say
> it's in mm when none of the devices have anything close to being usable.
> if this is what we see for most devices, we need to change the API into
> something less unreliable.
>
>

> First thought here is to normalize major/minor as well into a range where 1
> represents "normal touch". that makes scaling a lot easier when devices
> provide complete garbage and removes the pretense of accuracy.
>

To some degree this is already happening inside the driver. It tries to
rationalize the measured data by assuming a normal touch. Depending on the
implementation extreme input attempts either get ignored or clamped or ...
On top of that it seems that power saving is part of the decision making,
as small changes in covered area are not always reported.

After including smaller hands in the tests I am a bit more confident. There
is a reproducible relation between finger size and reported size.
The specific problem with device the I complained about was that it only
reports multiples of four, while the others dont.


>
> > On Mon, Nov 23, 2015 at 5:19 AM, Peter Hutterer <
> peter.hutterer at who-t.net>
> > wrote:
>
> well, we can use DMI information as well, that usually works well enough
> for
> touchpad devices. last option is a udev callout when we match specific
> system information, that callout can then dig into the device further. We
> do
> that for some touchpad firmware version already (see
> libinput-model-quirks).
>

No dmi on those devices.. libhybris getprop would provide something close
to that.
I could get the lacking resolution information from there.



> > > - do you have client-side code that makes use of these properties yet?
> I'd
> > >   like to have a look at it.
> > >
> >
> > We do use that information in the mirclient backend of qt. Not sure if qt
> > uses the information for anytihing internally - but it is available to
> > applications.
> > I mainly test with a plain-mir demo application called
> > mir_client_fingerpaint .
>
> do you have the source available somewhere?
>

http://bazaar.launchpad.net/~mir-team/mir/development-branch/view/head:/examples/fingerpaint.c

regards
Andreas
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