On Thu, Jun 25, 2015 at 08:12:36AM -0700, Bill Spitzak wrote: > Actually it seems incorrect to store the number of device units per mm as an > integer, since I would guess this number is near 1. However I don't know how > touchpads work so maybe the resolution is much much finer than I would > guess?
I think you're underestimating the precision of modern touchpads. The T440s have a resolution of 42 units/mm, the x220 from several years ago had somewhere around 130. The lowest value I've seen so far was 10. Cheers, Peter > To avoid floating point it might work to store the size of the touchpad in > mm instead. > > On 06/25/2015 08:06 AM, [email protected] wrote: > >From: Bill Spitzak <[email protected]> > > > >(changes from previous version: rounds the guess and changes 0 to 1, > >removed unused variables) > > > >Instead a default resolution is set if the device does not claim one. > >The selected value is a guess that the trackpad is 67 mm tall and > >that the device units are square. > > > >This estimate was arrived at by equating the results calculated when > >fake_resolution is on or off and computing the ratio of units to > >resolution and choosing the most popular value (yres = height / 66.666). > > > >Also fixes an apparent bug in computing motion_dist.scale_coeff, I > >believe the fake value was the reciprocal of the intended value. > > > >Unfortunately this patch has not been tested as I lack the ability to do so. > >It is unclear to me if the absinfo_x/y->maximum/minimum fields have been > >filled in before evdev_fix_abs_resolution is called, this patch > >assumes that. > _______________________________________________ wayland-devel mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/wayland-devel
