[RFC wayland-protocols] inputfd - direct input access protocol

Peter Hutterer peter.hutterer at who-t.net
Tue Apr 4 03:42:08 UTC 2017

On Mon, Apr 03, 2017 at 10:19:16PM -0500, Joshua Watt wrote:
> On 04/03/2017 07:22 PM, Peter Hutterer wrote:
> > On Tue, Apr 04, 2017 at 08:16:03AM +0900, Carsten Haitzler wrote:
> > > On Fri, 31 Mar 2017 17:29:19 +1000 Peter Hutterer <peter.hutterer at who-t.net>
> > > said:
> > > 
> > > If you're going to do this ... why not just do it for keyboards, mice, touch
> > > panels etc. too?
> > all these have desktop interactions that the compositor needs. joysticks
> > generally don't, the compositor doesn't care about the events.
> Is that really true? It seems like there are certainly use cases where a
> compositor *would* use the Joystick or gamepad as a primary navigation
> device (think SteamOS or some IVI shell). Maybe it could be said that these
> are all going to be custom compositors at this point, but I wouldn't want
> discount that such behavior could be desired in the future.

yes, you're right, but let me be more precise: keyboards/mice/... always [1]
have desktop interaction, the need to pipe them through to an application is
relatively niche. So unlike joysticks, the compositor cannot ignore them.
(and this was mostly in reply to the "sticking your head in the sand"

inputfd only gives you access to a device, it doesn't dictate how the device
is used otherwise. IOW inputfd lets you use the joystick in the compositor,
all you have to do is implement correct focus management.
That's an improvement over the current situation where you have multiple
processes accessing the device working with a cooperative model.

Note that it is also possible with this protocol to have a keyboard/mice/...
fd passed to the client if the latency of going through the compositor is
too high. Not in the immediate draft, but it's just one get_seat_keyboards()
or get_seat_mice() away.


[1] yes, I know "always" isn't the proper use of always, there are niche
cases where it doesn't apply, etc. but that's true for generally agreed upon
facts like "a hand has 5 fingers" too :)

More information about the wayland-devel mailing list