Re: Tablet support status (or, hitting jackpot with freeze break requests)

[Peter Hutterer <peter hutterer who-t net>]

On Wed, Aug 24, 2016 at 08:34:45PM +0200, Carlos Garnacho wrote:
> Hi!,
>
> As you probably know, there's been some work towards making drawing
> tablets supported in Wayland. As with other device configurability
> done previously to work on wayland too, this implies moving to
> libinput-based input, also on the x11 side through
> xf86-input-libinput.
>
> But this has supposed shuffling a lot of pieces around, all tablet
> configuration happening in gnome-settings-daemon should be now
> performed by mutter (as with other device configurability really), and
> so do other miscellaneous things like mapping buttons to keycombos or
> showing and OSD with the tablet button mapping.
>
> And it's actually in x11 support where timing got a bit tight, in the
> first place mutter hasn't grown yet the support to apply our tablet
> configuration on x11 (I've got code started here), but also there is
> some configuration toggles still missing on xf86-input-libinput that
> are needed to have 100% configuration support (stylus pressure and
> "keep aspect" [1] settings most notably).
>
> So the status of my TODO to get to the full picture is:
>
> - Pad OSD needs moving to being handled by gnome-shell
> (https://git.gnome.org/browse/gnome-shell/log/?h=wip/pad-osd). Florian
> promised me a review, which I expect at some point, although he jumped
> into vacation since.
>
> - gnome-control-center needs changing to modifying the same settings
> that mutter listens to, and adapt to the new configuration mockups
> (https://git.gnome.org/browse/gnome-control-center/log/?h=wip/garnacho/wayland-tablet)
>
> - mutter needs to gain support for the X11 configuration, this is WIP,
> but I'm optimistic that this can be sorted out for 3.22.0 if we go
> ahead with all these changes and deem this a regression, it's
> basically the same than we're doing currently on gnome-settings-daemon
> for the most part, albeit maybe depending on brand new (read: still
> undone) xf86-input-libinput features. Peter, feel free to crush my
> hopes :).

KeepAspect or something similar should be in the xf86-input-libinput driver
because that's where we control (some) of the pointer motion. For Wayland
it's obviously in the compositor.

For the pressure curve I'm not sure, I think we said we move this
client-side long-term?

Cheers,
   Peter

> - After that, we can safely shut down the wacom plugin from
> gnome-settings-daemon, everything it was doing is now taken care
> somewhere else. I'm not posting a branch but you can imagine the
> resulting patch.
>
> So the summary of freeze requests are:
> - Pushing wip/pad-osd in gnome-shell
> - Pushing wip/garnacho/wayland-tablet on gnome-control-center
> - Disabling/dropping the wacom module from gnome-settings-daemon
>
> I know this implies a lot of late changes: dropping support for an
> entire driver, new UI, losing some configurability at places
> (temporarily, I hope), ... so I may understand if feels uneasy. Some
> "middle ground" options I might think of are:
>
> - Still moving OSD and configuration management to mutter, although
> with mixed xf86-input-libinput/wacom driver support to ensure we can
> make X11 supported again ASAP.
> - Wire mutter to using gsettings from gnome-settings-daemon so
> x11/wayland share the same settings, and preserve the wacom plugin in
> g-s-d for X11 mostly as-is. It would still be more convenient to have
> the OSD in gnome-shell nonetheless.
>
> So, how far would you let me go? :)
>
> Cheers,
>   Carlos
>
> [1] So eg. a 4:3 tablet sacrifices some space in order to preserve
> both axes unstretched if eg. mapping to a 16:9 monitor