Trivial change to mouse acceleration code would make it less bad

Jim Gettys Jim.Gettys at hp.com
Wed Oct 27 12:47:43 PDT 2004


It is certainly possible.  In fact, why don't you prepare a patch for
people to try out?
			- Jim


On Wed, 2004-10-27 at 21:17 +0200, Simon Strandman wrote:
> Would it be possible to take the mouse-acceleration code from kdrive and
> adapt it to xorg? kdrive has much nicer mouse-acceleration IMHO.
> 
> 
> > Hello.
> > 
> > I read the mouse acceleration code in xf86Xinput.c and noticed that 
> > there are 2 different formulas depending on whether threshold is 0 or 
> > not. The formula for threshold != 0 applies the standard method of 
> > acceleration while the one for 0 applies an exponential one.
> > 
> > Now I personally don't like any kind of mouse acceleration but the 
> > exponential method uses the variables dxremaind and dyremaind to prevent 
> > accumulation of rounding errors which is a very good idea.
> > 
> > When a user has a mouse with a high resolution, he might want to use for 
> > example "xset m 1/2 1" to halve the pointer speed but with the current 
> > implementation this makes the pointer stall when the mouse is moved 
> > slowly. (In this case, "xset m 1 0" could have been used for the wanted 
> > effect but this is a coincidence.)
> > 
> > That's why I suggest that the old acceleration code uses the 
> > dxremaind/dyremaind variables, too.
> > 
> > Long term, the method proposed by Eugenia [1] look promising although 
> > I'm against scaling the pointer movement according to screen resolution 
> > but short term, my proposed change would allow freely scaling the mouse 
> > speed without the mentioned problem and without breaking any 
> > compatibility (I hope).
> > 
> > [1] http://freedesktop.org/bugzilla/show_bug.cgi?id=138
> > 




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