[PATCH libinput 01/10] Replace pointer acceleration with a much simpler linear one
steve at snewbury.org.uk
Fri Sep 19 02:09:58 PDT 2014
On Fri, 2014-09-19 at 15:44 +1000, Peter Hutterer wrote:
> We ran a userstudy, evaluating three different accel methods.
> Detailed results are
> available at:
> We found that there was little difference between the method we had
> libinput 0.6 and this three-line function. Users didn't really
> notice a
> difference, but measured data suggests that it has slight advantages
> in some
> The method proposed here is the one labeled "linear" in the paper,
> its profile
> looks roughly like this:
> where the x axis is the speed, y is the acceleration factor.
> The first plateau is at the acceleration factor 1 (i.e. unaccelerated
> movement), the second plateau is at the max acceleration factor. The
> in the code defines where and how long the plateau is.
> Differences to the previous accel function:
> - both inclines are linear rather than curved
> - the second incline is less steep than the current method
> From a maintainer's point-of-view, this function is significantly
> easier to
> understand and manipulate than the previous one.
I'm going to read the report, but I would like to just state my
initial feeling on this. Right now, in my experience*, the pointer
acceleration in libinput/weston is inferior** to that currently in
Xorg. I find it relatively difficult to accurately position the
pointer in Weston while at the same time being able to comfortably
move the pointer over larger distances in a predictable manner. The
Xorg code has been very well tuned over the last few years and IMHO is
at least as good as the Windows implementation (from a user point of
Any comparison between the libinput/weston implementations needs to be
base-lined against current Xorg and Windows/OSX! I'm certainly not
opposed to improvements!
Maybe my concerns are unfounded, I'll have a read of the report now...
* Using a Synaptics touchpad
** For all I know it's the same code (haven't checked) but the
parameters must be different or there's a bug somewhere.
-------------- next part --------------
A non-text attachment was scrubbed...
Size: 181 bytes
Desc: This is a digitally signed message part
More information about the wayland-devel