Re: Touch screen with X multi monitor setup

On Thu, 9 Nov 2023 10:47:56 -0500
Dennis Clarke <dclarke@blastwave.org> wrote:

> On 11/9/23 03:10, Milan Obuch wrote:
> > Hi,
> > 
> > after some years using Acer T231H1 monitor for its monitor role, I
> > decided now to try its touch screen interface. It uses USB
> > interface, plugging it into my workstation shows just
> >   
> 
>      I also brought home a large touch screen back in 2014 or so. It
> is actually an HP branded "digital display":
> 
>      LD4220tm LCD Interactive Display  model XH216AA

[ snip ]

> s$ xrandr
> Screen 0: minimum 320 x 200, current 5760 x 1080, maximum 16384 x
> 16384 DisplayPort-0 connected primary 1920x1080+0+0 (normal left
> inverted right x axis y axis) 930mm x 523mm
>     1920x1080     60.00*+  50.00    59.94
[ snip ]
> DisplayPort-1 connected 1920x1080+1920+0 (normal left inverted right
> x axis y axis) 521mm x 293mm
>     1920x1080     60.00*+  50.00    59.94
[ snip ]
> DisplayPort-2 connected 1920x1080+3840+0 (normal left inverted right
> x axis y axis) 521mm x 293mm
>     1920x1080     60.00*+  50.00    59.94
[ snip ]
> DisplayPort-3 disconnected (normal left inverted right x axis y axis)
> s$
> 
> So there you see Screen 0 on DisplayPort-0 where the resolution is
> reported as 5760 x 1080.  If I try to use the touch screen feature it
> just maps the single monitor over that entire 5760 pixel wide stuff.

So this situation is basically the same as that of mine.

> > Acer monitor with touch screen is connected via DVI-D-1 connector in
> > this case. Problem is absolute location of touch being not correct,
> > coordinate Y (up/down) is OK, but coordinate X (left/right) is not.

[ snip ]

> I have not figured it out either but am willing to experiment a bit
> and see what happens. Maybe we can sort out whatever magic is
> required and here I do see :
> 
>      https://wiki.archlinux.org/title/Touchscreen

I'll looke there for some ideas...

> > And, one more idea, how could I use multiple touch screen monitors?
> > At present, I have no such setup, but there are various small
> > computers with multiple video connectors, often dual HDMI, so I can
> > imagine it could be usefull. And how about rotated screen? For
> > tablets and touch screen notebooks, it could be often the case (my
> > GPD small notebook, not touch screen, has 1280x720 resolution, but
> > it is actually rotated 720x1280 screen).  
> 
> Exactly the right questions. I am thinking that all my monitors can be
> touch screen but then we need to sort out the mapping of the input.
> Here I did find about something called libinput-tools in Debian Linux.

Input, input, input... Ha! There is x11/xinput port, installing it,
looking into xinput.1 man page, issuing

xinput --map-to-output 12 DVI-D-1

et voila, it works as expected now! Thanks for hint! I am going to test
it a bit more, but basically I am done now with this task.

Regards,
Milan