Bug 400229

Summary:	Flat and Adaptive acceleration profiles both do the same thing
Product:	[Applications] systemsettings	Reporter:	Damian Höster <damian.hoester>
Component:	kcm_mouse	Assignee:	Unassigned bugs mailing-list <unassigned-bugs>
Status:	RESOLVED DUPLICATE
Severity:	major	CC:	alexmasonpro, damian.hoester, nate, subdiff, unassigned-bugs
Priority:	HI	Keywords:	usability
Version:	unspecified
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:
Attachments:	screenshot of the mouse settings in KDE Plasma 5.14.2

Description Damian Höster 2018-10-24 06:27:01 UTC

It is really strange for such a configurable desktop environment like KDE Plasma that there is no way to change the mouse sensitivity in the settings.
This is a crucial feature for me, because I don't want any mouse acceleration on my system. But when I change mouse acceleration to 1.0x, the cursor is much to slow.
I hope this feature will be added in the future, I will continue to use the Deepin Desktop environment until then.

Comment 1 Nate Graham 2018-10-24 14:21:49 UTC

Please attach a screenshot of your mouse settings.

Comment 2 Damian Höster 2018-10-26 19:25:32 UTC

Created attachment 115911 [details]
screenshot of the mouse settings in KDE Plasma 5.14.2

Betriebssystem: Reborn OS 
KDE-Plasma-Version: 5.14.2
Qt-Version: 5.11.2
KDE-Frameworks-Version: 5.51.0
Kernel-Version: 4.18.16-arch1-1-ARCH
Art des Betriebssystems: 64-bit
Prozessoren: 8 × Intel® Core™ i7-3720QM CPU @ 2.60GHz
Speicher: 15,5 GiB Arbeitsspeicher

Comment 3 Nate Graham 2018-10-26 19:57:25 UTC

Thanks! The way to have zero acceleration is to set the "acceleration profile" to "Flat". Then the slider just determines the sensitivity.

Comment 4 Damian Höster 2018-10-26 20:19:47 UTC

I am a bit confused.
I am pretty shure it said "Pointer acceleration" and you could set it from 0.1x to 20.0x . But after I installed all the updates, the mouse settings changed to what you can see in the screenshot. Anyway...
I will try immediately if the "Flat" mode works as expected.

Comment 5 Nate Graham 2018-10-26 20:22:32 UTC

(In reply to Damian Höster from comment #4)
> I am a bit confused.
> I am pretty shure it said "Pointer acceleration" and you could set it from
> 0.1x to 20.0x . But after I installed all the updates, the mouse settings
> changed to what you can see in the screenshot. Anyway...
> I will try immediately if the "Flat" mode works as expected.

Yes, the old interface had that, but it didn't support the modern Libinput library and was using forcing your mouse to use old unmaintained drivers. But this new one properly supports using Libinput as a backend driver, and with Libinput, the way to turn off acceleration completely is to use the "Flat" profile.

If you find that the new one doesn't work properly, please fine another bug to track that. Thanks!

Comment 6 Damian Höster 2018-10-27 21:34:24 UTC

Nope.
Setting the profile to "Flat" does not remove pointer acceleration.
In both profiles changing "Pointer speed" changes the pointer acceleration.
Could it be that you get static acceleration in "Flat" mode and adaptive acceleration (whatever that exactly means) in "Adaptive" mode?

Comment 7 Nate Graham 2018-10-28 03:30:18 UTC

OK, it seems like to get zero acceleration and true 1:1 movement mapping, you need to set the profile to flat, and the speed slider to the middle point. Does that work?

Comment 8 Damian Höster 2018-11-22 00:30:27 UTC

No, only when I drag the speed slider to the left I get no pointer acceleration (in both Flat and Adaptive mode), but then the mouse is unusably slow.
There does not seem to be big difference between Flat and Adaptive mode, in both modes the pointer acceleration changes with the slider.

Comment 9 Nate Graham 2018-11-24 20:07:07 UTC

Can you detect any difference at all between the "Flat" and "Adaptive" acceleration profiles?

Sorry to sounds like such an idiot here, but I can't tell the difference myself and I'm not sure whether this is because they're actually identical, or I'm just not very sensitive to the difference.

Comment 10 Damian Höster 2018-11-24 23:18:46 UTC

No, I can't make out a real difference either.
I wonder to what the acceleration could adapt to in adaptive mode.

Comment 11 Alex Mason 2018-12-11 20:50:50 UTC

Mouse KCM does indeed not change the acceleration profile on X11 libinput pointers.
Simple way to see: xinput list-props on your mouse device. libinput Accel Profile Enabled is default 1,0. Changing to 'Flat' profile on GNOME changes this to 0,1. Change it to 0,1 through xinput and you'll no longer have mouse acceleration. I believe the mouse KCM is changing it to 1,1, which still results in mouse acceleration.

Comment 12 Alex Mason 2018-12-11 23:59:40 UTC

I have no experience with the KDE codebase, but I took a look around out of curiosity.
At line 150 of plasma-desktop/kcms/mouse/backends/x11/x11_libinput_dummydevice.cpp, LIBINPUT_PROP_ACCEL_PROFILE_ENABLED is defined as a boolean. However, xinput list-props shows two booleans for "libinput Accel Profile Enabled". 1 0 corresponds to Adaptive profile while 0 1 corresponds to Flat profile.
Might be a lead.

Comment 13 Nate Graham 2019-01-12 22:55:30 UTC


*** This bug has been marked as a duplicate of bug 398713 ***