Bug 430324

Summary:	Support for libinput backend missing, touch feature tweaks and mapping not good on xf86-input-wacom
Product:	[Applications] systemsettings	Reporter:	Raghavendra kamath <raghu>
Component:	kcm_wacomtablet	Assignee:	Valerii Malov <jazzvoid>
Status:	REPORTED ---
Severity:	normal	CC:	arkonbob
Priority:	NOR
Version First Reported In:	unspecified
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Raghavendra kamath 2020-12-13 04:49:07 UTC

SUMMARY
Currently the wacom kcm is dependent on the xf86-input-wacom. Libinput supports the tablet well now a days but there is no support to use libinput as backend. While xf86-input-wacom is good, it fails miserably when the tablet has touch and guesture support. The settings is not enough to make it work properly for example two finger or three finger tap to right click doesn't work.

Where as libinput handles the touch events as touchpad and offers better experience. But there is one problem in using it. There is no KCM to map the tablet area to screen so if your monitor has 16:9 ratio and the tablet has 16:10 working area the perfect circles you draw will be ellipse

Going forward when we will switch to wayland, we won;t be able to use xf86-input-wacom, so it is better to adapt to libinput and port the KCM to it.

There is already some volunteer work on this here - 
https://invent.kde.org/matthews/kcm-tablet

I contacted the author and they imported their repo to KDE invent. They say that some of their MR for some missing features in kwin are ignored. I would request the developers to look into it. 
Here is one of the MR - https://invent.kde.org/plasma/kwin/-/merge_requests/251#note_103011

STEPS TO REPRODUCE
1. Uninstall xf86-input-wacom or open plasma settings under wayland
2. There will be no kcm to configure your tablet.

Comment 1 Bob 2021-01-31 00:29:33 UTC

Best approach is to split handling of the tablet. Touch will be handled by libinput, stylus by xf86-wacom:

Create a file named /etc/X11/xorg.conf.d/90-libinput-wacom.conf with the following contents, and then reboot:

```
Section "InputClass"
         Identifier "libinput Wacom touchpad override class"
         MatchUSBID "056a:*"
         MatchDevicePath "/dev/input/event*"
         MatchIsTouchpad "true"
         Driver "libinput" 
EndSection
```

Source:
https://github.com/linuxwacom/xf86-input-wacom/issues/28#issuecomment-420737038

There is one issue, if you have a libinput touchpad, that will be replaced in KDE settings with the Wacom Touchpad (I'm about to create a bug report for that).