On Wed, May 04, 2016 at 07:13:43AM +1000, Peter Hutterer wrote: > Trackballs are effectively stationary devices and can be positioned at any > rotation. They are also employed by users with impaired dexterity which > sometimes implies that they are positioned at an non-default angle to make the > buttons easier to reach. > > Add a config option for rotation for trackball devices. Currently only > supported for 90-degree angles, if there is a need we can add more angles > later. > > Signed-off-by: Peter Hutterer <peter.hutte...@who-t.net> > --- > I'm not 100% sure yet that this is the feature we should have. Rotation > itself is important for trackpoints, no doubt, but I'm contemplating whether > to make this a more generic form like a matrix. It makes decisions of > precedence a lot easier, especially if we need to add other options later > that may overlap or conflict with rotation (admittedly, it just shifts that > decision to the caller). but a matrix can also be misused easier and makes > it harder for libinput to detect what the caller wants to do. while this > doesn't have a use-case yet for this feature, sometimes knowing what the > caller wants to do allows us to modify other features.
a few notes from my meeting with Benjamin today: if we expose the matrix, what would we gain: immediate support for translation, shearing, scaling and reflection. translation and shearing make no sense for relative devices. scaling is effectively only a way to work around/against pointer acceleration and we don't want to enable that. reflection *could* be interesting but we failed to come up with a reasonable use-case where it is needed on relative devices. so it looks like this API is indeed the best approach. Cheers, Peter _______________________________________________ wayland-devel mailing list wayland-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/wayland-devel
