From the QtMoko Report[1] announce:
> Currently the Qt-Embedded deb installs itself into /opt in
order to not
> mess, or conflict with the non-embedded Qt variant provided by
Debian.
> There are demos installed to /opt/qt-embedded/examples, and I
did try
> out a few of them. They appeared to work properly, but there is
a
> problem with touchscreen input:
> When touching the screen, Qt properly detects a mouse-press at
the right
> location of the screen. But then when moving the pointer, it
runs away
> in a non-linear fashion.
> I later concluded that it looks like this:
> pos_new = new_absolute_coordinates + distance_to_last_position
> This is a serious issue and needs investigating. We suspect
that the
> Qt-Embedded LinuxTP mouse driver is doing something nasty!
>
> If you want to play around with it, this is how:
> ```
> # set up environment
> export PATH=/opt/qt-embedded/bin:$PATH
> export LD_LIBRARY_PATH=/opt/qt-embedded/lib:$LD_LIBRARY_PATH
> export QWS_MOUSE_PROTO=linuxtp:/dev/input/touchscreen
> cd /opt/qt-embedded/examples
> # try out whatever example you like, and dont forget to pass
the -qws commandline option
> ```
A workaround has been proposed later on the list[2]:
> On Tue Jun 14 16:41:23 CEST 2016, Josua Mayer wrote:
>
> > When touching the screen, Qt properly detects a
mouse-press at the right
> > location of the screen. But then when moving the pointer,
it runs away
> > in a non-linear fashion.
> > I later concluded that it looks like this:
> > pos_new = new_absolute_coordinates +
distance_to_last_position
> > This is a serious issue and needs investigating. We
suspect that the
> > Qt-Embedded LinuxTP mouse driver is doing something nasty!
>
> A quick suggestion that might not be practical: have you tried
using the
> linuxinput driver instead?
>
> http://doc.qt.io/qt-4.8/qt-embedded-pointer.html
>
> For example, when I compiled Qt for the Kobo Mini, I compiled
it with
> linuxinput support (-qt-mouse-linuxinput) and selected the
driver using an
> environment variable at run-time:
>
> QWS_MOUSE_PROTO=linuxinput:/dev/input/event1
>
> I've always had difficulty with tslib but linuxinput has mostly
worked for
> me, once I've figured out which device file it needs to read
from.
>
> David
Please, note that I didn't try myself to reproduce this issue. I'll
try it later.
Adrien
[1]:
http://lists.goldelico.com/pipermail/community/2016-June/001420.html
[2]:
http://lists.goldelico.com/pipermail/community/2016-June/001424.html
Reported by Adrien Dorsaz, Aug 29, 2016