[Question] ZaphodHeads, ServerLayout without position information, and touchscreens

[Böszörményi Zoltán]

Hi,

2020. 07. 17. 9:44 keltezéssel, Hugh Chang írta:
> Dear all,
> 
> I'm writing a document to guide how to configure xorg.conf for multiple touchscreens as 
> attached.
> I think that I've almost finished it but I don't know how to configure xorg.conf
> when ServerLayout is described without position information for multi-seat setup with one 
> graphic card (zaphod heads).
> I could not find a proper solution and I'm asking your advice.
> I'll greatly appreciate for any hint from you.

for dynamic seats, simply there is no solution.

The "xinput map-to-output ..." command would be nice but
1) it needs that Xorg has already started so preset configuration is out of question, and
2) it doesn't survive hotplugging if the touchscreen device is USB based.

For fixed configuration, I have solved this a while ago.

What you need is xorg.conf template files for sed substitutions and this utility:
https://github.com/zboszor/touchscreen-transform , formerly known as
https://github.com/SICOM/touchscreen-transform

Full disclosure: this utility blatantly copied the xinput 1.6.2 code
for computing the values for Option TransformationMatrix.

==========================================================
$ ./touchscreen-transform
Usage: ./touchscreen-transform [-i index] { -r NxM [-R {normal|left|right|inverted}] ... }
-r, --resolution NxM
	screen resolution
-R, --rotation {normal|left|right|inverted}
	screen rotation
-i index
	For multi-screen setup, the touchscreen is
	attached to the (zero based) indexth screen
Options -r and -R are positional and can be repeated.
==========================================================

The utility takes a series of -r (resolution) and -R (rotation)
options and an index for the 0 based array of screens/monitors
forming the whole canvas X works on and assumes they are put side by side.

The output is a series of floats that is the TransformationMatrix
you can use for the touchscreen attached to the ith monitor.
See the INPUTDEVICE SECTION in man 5 xorg.conf about Option
TransformationMatrix.

E.g.:

$ ./touchscreen-transform -r 1024x768 -r 1024x768 -i 1
0.50000 0.00000 0.50000 0.00000 1.00000 0.00000 0.00000 0.00000 1.00000

For completing the configuration (e.g. binding the input device properly
to a given USB slot) is left to you to discover. "man 5 xorg.conf", "man 4 evdev"
and "man 4 libinput" should have everything you need.

Best regards,
Zoltán Böszörményi

> 
> Best regards,
> Hugh Chang
> 
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