libinput: the road to 1.0

Bill Spitzak spitzak at
Mon Feb 23 11:14:35 PST 2015

On 02/23/2015 01:50 AM, Michal Suchanek wrote:
 > What is the semantic of speed for trackballs? Technically the DPI of
 > scanning the ball movement can be determined and is often part of the
 > specification but the perceived speed will likely depend on ball size
 > and mounting as well.

The trackball scanner is focused on the surface of the ball, so this 
should mean the size of the ball does not matter, as that point is 
moving the same speed as the point the fingers move (well to be exact 
only the point exactly on the opposite surface of the ball is moving at 
that speed. Looking at the trackball I have I can see the camera is not 
actually at the bottom of the sphere, but somewhat up to the back, 
opposite a point closer to the front than the top of the sphere. This 
may indicate the manufacturer had to take this into consideration).

I have a Kensington trackball (Expert Mouse Model #K64325) and it was 
just plugged into an existing Ubuntu machine that I don't think knows 
much about it, so I assume it is treating it as a generic mouse. In this 
case the speed of both the trackball and the scroll ring are fine, or at 
least certainly not orders of magnitude wrong. Also appears to match how 
it behaves in Windows. Not sure if that means anything however.

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