(In reply to Peter Hutterer from comment #16) > Adam: I'm really hesitant to put it into libinput because I'm not sure the > problem scope is well understood (at least by me) and what the actual point > of it is. So far it's been a "would be nice" but - at least these days :) - > we require a bit more information about use-cases and precise behaviours. > > libinput provides two values for wheels: physical degrees and concrete > steps, so for most events on most mice you get a (15°, 1 step) tuple. There > is no room for acceleration there, if anything the acceleration would have > to be in the xf86-input-libinput driver. There we recently added a patch to > adjust the scroll distance based on the angle (see Bug 92772) so a wheel can > now produce smooth scrolling for XI2 clients. > > But as for any actual acceleration, someone (you? :) would have to come up > with a good plan of what the actual use-case is to solve and how to solve > it. Not necessarily with code at first but at least to get a good idea of > what's happening. And of course we'll need buy-in from the bigger desktop > environments.
I've been thinking a bit about this. Let me start with this proposal (I can open a new bug if we want to continue this). Use case: - Scrolling through a long document is slow with a mouse wheel Prior work showing benefits of wheel acceleration: - macOS - Chrome OS Requirements: - Don't break anything - Require minimum changes from clients Proposal: - Mouse wheel acceleration at the libinput level, only for mouse wheels - Do no acceleration on values returned from libinput_event_pointer_get_axis_value_discrete, this keeps the promise in the API of reporting "physical mouse wheel clicks" and keeps us from needing to implement a new "get unaccelerated" API - Ensure that legacy X wheel events (pre-XI2.1) are not accelerated Open questions: - Does this cover enough clients without breaking things? Chrome and Firefox support XI2.1, so this would accelerate those programs. - Under X or XWayland, is it possible to accelerate XI2.1 events but not the legacy events? Or are the legacy events generated automatically? - Or is it ok to accelerate legacy X wheel events? emacs has scroll acceleration already, and other clients may as well. Again, I can open another bug if this seems reasonable. I don't want this to continue in a WONTFIX bug :) -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg-server in Ubuntu. https://bugs.launchpad.net/bugs/619403 Title: [KDE] no option for mouse wheel acceleration To manage notifications about this bug go to: https://bugs.launchpad.net/xorg-server/+bug/619403/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : [email protected] Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp
