eGalax touchscreen and RandR rotation

[Sandeep]

For input, I am using xf86-input-evdev . I am not using the proprietary
eGalax driver. I might be wrong about the input rotating with the screen.

The problem is the mouse cursor/pointer location does not correspond to the
touch input. The movement of the cursor does correspond to the touch input,
but seems to be rotated the same way the screen has been rotated.

For example, assume a 11 inch display with a resolution of 1280*800 . The
default orientation is the upright landscape orientation. I use the KDE
screen rotation utility (krandrtray) to rotate the screen left by 90
degrees(portrait). When I touch near the top left corner (in the upright
landscape orientation), the mouse cursor jumps to a corresponding position
near the top left corner in portrait mode.

So, there is a definite pattern connecting the touch input position and the
mouse cursor position - it looks like the input position is rotated the
same way display was rotated.

If I use the coordinate transformation matrix in the script here:
https://wiki.archlinux.org/index.php/Multitouch_Displays#Rotating_the_touch_screen
            (see "Rotating the touch screen" section)

It works correctly - the mouse cursor follows the touch input.

Also, this problem is not specific to KDE, but also GNOME and even the
Fluxbox window manager.

-Sandeep






On Mon, Oct 21, 2013 at 2:41 PM, Peter Hutterer <peter.hutterer at who-t.net>wrote:

> On Fri, Oct 04, 2013 at 05:36:00PM -0700, Sandeep 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:
> > http://www.youtube.com/watch?v=OviHJmjhoOI
> >
> > 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 bugs.freedesktop.org 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?
>
> what driver are you using? no X driver currently rotates with the screen,
> it's something that needs to be triggered from the outside so chances are
> that whatever triggers the rotation in KDE is triggering the wrong thing.
>
> Cheers,
>    Peter
>
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