eGalax touchscreen and RandR rotation

Sandeep sandy.8925 at
Thu Oct 10 23:48:20 PDT 2013

I think I figured out what's wrong.

udev creates two input devices for the touchscreen:
- Touch input
- Mouse input

I guess this is done to emulate the touchscreen as a mouse so that it can
be used with existing GUI's without requiring applications to handle touch

Mouse input is configured to be relative by default, touch input is
configured to be absolute by default.
The video shows that the touchscreen input is also translated as mouse
input which is relative, so the mouse pointer moves accordingly. The touch
input itself is invisible, and it looks like no application is using it,
and the only visible change is in the mouse pointer.

The solution then seems to be that the mouse input created for the
touchscreen should be configured as an absolute device, which will then
make it work correctly.


On Fri, Oct 4, 2013 at 5:36 PM, Sandeep <sandy.8925 at> wrote:

> Hi,
> I have an Acer Iconia Tab W500. It has an eGalax touchscreen. Single touch
> input  works.
> I mainly use KDE, and when I rotate the screen using the Krandrtray
> application, the mouse input works fine, but the touchscreen input does not
> work correctly.
> Here is a video showing the problem:
> It looks like the touch driver rotates the input in the same way that the
> screen is rotated, thus producing wrong/unexpected behaviour.
> I tried searching for existing bugs at and it
> doesn't look like any of them cover this problem. Does anyone know what the
> problem might be, and how I can figure out where the problem lies?
> Thanks,
> Sandeep
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