[Wayland-bugs] [Bug 85715] wl_fixed is not precise enough for high dpi mice

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=85715

--- Comment #3 from Derek Foreman <derekf at osg.samsung.com> ---
Libinput until 58e0fe270 was accidentally rounding some data internally, but
now as far as I can tell it's weston.

Pointer-lock is what a game would use to get "raw" mouse data?  I think there's
a question as to whether that will be normalized at all by libinput - it may be
the case that it'll come out the other side entirely on the left of the radix
point, and this problem doesn't actually exist there.

Actually, I think even normalized, with the most ridiculous mouse I've seen
(8200dpi) it's still like .049 units per "dot" without the accel curve's
intervention.  If I'm doing my math right we're good to 102400DPI before we
can't represent a dot in the absence of an accel curve.  I don't think anyone
will argue a need for that.  It won't be me in any event.

Storing doubles internally and sending wl_fixed over the wire seems like it
should be a solution to me.

Saving the rounded part and appending it to the next motion would fix it too, I
think, but this seems a little uglier from an implementation perspective to me.

I guess right now clients are receiving a lot of motion events they don't need
- they're even receiving motion events with no change when the round off
occurs.  Should they only receive change above a certain threshold?

-- 
You are receiving this mail because:
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/wayland-bugs/attachments/20141101/bddb8cae/attachment-0001.html>