Re: Wacom calibration results are off (wrong area)

Thanks for the investigation Josh. I will look into this.

Joaquim Rocha

----- Original Message -----
From: "Josh Berry" <taeric gmail com>
To: "Joaquim Rocha" <jrocha redhat com>
Cc: gnomecc-list gnome org
Sent: Friday, June 21, 2013 7:04:44 PM
Subject: Re: Wacom calibration results are off (wrong area)

I think I'm now able to reproduce exactly what we are seeing.  The problem
seems to be that once the calibration goes wrong once, it can not correct
itself.  Specifically, if we set the area value in dconf to be a bogus
value, then the calibration will remain bogus.  My hunch is simply because
the values of the Calib struct old_axis are used to "scale" the resulting

This actually describes what I was seeing rather well, which was that the
area of the calibration will get smaller and smaller with each successive
attempt at calibration.  (That is, each successive calibration would reduce
the "usable" area of my screen for the pen, such that moving the pen across
a subset would move the cursor across the whole screen.)

I will run some tests to really show this, but it seems that the assumption
that the scale of the last calibration was correct is problematic.   Other
than being nuclear on that code, is there a way I could modify the code
such that a terrible calibration does not make it impossible to get a good


On Mon, Jun 17, 2013 at 11:26 AM, Josh Berry <taeric gmail com> wrote:

On Mon, Jun 17, 2013 at 9:32 AM, Joaquim Rocha <jrocha redhat com> wrote:

Hi Josh,

Looks like the commit you refer to is in included from GNOME Control
Center's release 3.7.1 on.

The ideal way to test this would be for you to compile and test GNOME
Settings Daemon and GNOME Control Center.
This may not be the "easy way" you are asking for though so one idea that
occurs to me is for you to try a recent Fedora 19 live image:

To make sure that the image you try has a recent version of the Control
Center, don't forget to run "gnome-control-center --version".

Apologies, the "easy thing" I am unsure how to do is build and run an old
version.   I have actually compiled and run the latest
gnome-control-center.  And that seems to set the correct values.  At least,
running it several times consistently sets similar values that work.
(Before I put in a bug, I wanted to make sure I could reproduce in the
latest version.)

However, I am now unable to reproduce this with the control center that is
default on my system.  The version on my machine is 3.6.3, the version I
built and ran is 3.8.3.  So, at this point my hunches are up.   I had
thought I had seen a message about defaulting to "last device calibrated"
somewhere.  I will try and hunt that down when I can this evening.

Anything else I can run to try and isolate this?  (I can still run a live
image, if that might provide clues.)



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