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:
> http://www.who-t.net/publications/hutterer2014_libinput_ptraccel_study.pdf > > We found that there was little difference between the method we had > in > 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 > use-cases. > > 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 > threshold > 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. > Hi Peter, 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 view). 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.
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