Input and games.

[Pekka Paalanen]

On Thu, 2 May 2013 18:18:27 +0000 (UTC)
Rick Yorgason <rick at firefang.com> wrote:

> Pekka Paalanen <ppaalanen at ...> writes:
> > Yes, I agree.
> > 
> > Even if BP was not a nesting compositor, making the home button
> > minimize the active window would usually get you to the BP right
> > under it. The task switcher would be more reliable, though, and
> > also allow to get back to the game. It is all mostly a question of
> > making the Wayland server or the DE controllable with a gamepad.
> > 
> > In summary, I don't think we need to treat the home button
> > specially in the protocol.
> 
> I've been looking into how the Steam overlay works on Linux, and it
> seems to inject code into the target app using LD_PRELOAD. This is
> how it draws its interface over the game, and how it intercepts the
> Shift+Tab shortcut to open the overlay,

Uh oh, yuk...

I wonder if one would have serious trouble achieving the same on
Wayland. X is so much more liberal on what one can do wrt. protocol and
the C API. For instance, in X I believe one can query a lot of stuff
from the server, in Wayland nothing. In X a window reference is just an
integer, and if you get something wrong, I think you get an error that
you can choose to handle non-fatally. In Wayland, you have a pointer,
that means you are susceptible to use-after-free and segfaults, and if
you do something wrong, the server disconnects the whole client on the
spot.

> and I see no reason why this
> technique wouldn't also work for the home button, so I rescind the
> idea that making it a global message might be useful.

It depends very much on the API that LD_PRELOAD lib is intercepting,
whether it is just ugly or near impossible. I'm hugely sceptical.


Cheers,
pq