[RFC PATCH wayland-protocols] Introduce logical output protocol for Xwayland
ofourdan at redhat.com
Fri Jun 30 08:38:07 UTC 2017
> On Thu, Jun 29, 2017 at 04:44:34PM +0200, Olivier Fourdan wrote:
> > This introduces a new protocol for the compositor to describe outputs
> > size in a logical way for Xwayland.
> > This is needed for X11 applications that would want to configure an X11
> > window based on the size of the output, without knowing the output scale
> > factor applied by the compositor to the corresponding Xwayland surface.
> So, yes, Xwayland needs this, and I see no way around it. On IRC you
> raised the question whether this should really be part of wl_output is a
> good question indeed. Would it ever be useful for a regular Wayland
> client to know about this?
> For fullscreening, we already communicate the expected size (in the
> surface coordinate space) via the xdg_toplevel.configure event. Knowing
> how much space is available on a work space (i.e. possibly useful for
> avoiding too big windows) wouldn't be possible as this wouldn't include
> panels, launchers etc, nor would the client know on what output it'll be
> started (yet at least).
> Adding it to wl_output might be fine anyway, as we could refer to it
> when talking about how clients should not rely on calculating its own
> "output size" by looking at wl_output::mode, wl_output::transform and
> wl_output::scale, but we could just as well clarify that they simply
Yes, on further consideration and as we discussed earlier today on irc, this might be of interest to some other clients as well, so adding it to the existing wl_output interface makes sense imho, rather than adding an Xwayland specific interface...
> Anyway, some comments about this proposal below:
> As mentioned, I'd say not talking about "scaled" is better, but rather
> talk about coordinate spaces, and how a surface size is represented in
> it. wl_output talks about the "compositor space" which is indeed what we
> are communicating here, but having an example about how the size of a
> surface normally will have corresponding size in the compositor space
> would be good.
> For example, a surface with the same size as the size advertised here
> will normally have the same size as the monitor when displayed could be
> such an example.
I'll take this as an example in the wl_output addition indeed.
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