[PATCHv2] Add name event to xdg-output

[Philipp Kerling]

Hey,

I'll just reiterate one point from the prior discussion.

> On Mon, 9 Apr 2018 08:13:15 -0400
> Drew DeVault <sir at cmpwn.com> wrote:
> 
> > Good feedback.
> > 
> > On 2018-04-09 11:09 AM, Pekka Paalanen wrote:
> > > Does this name correspond to the physical connector or to the
> > > specific
> > > monitor connected? Or some abstract "output" concept, see the
> > > next
> > > paragraph about clone mode.  
> > 
> > Doesn't matter, whatever the compositor wants. Should be unique to
> > each
> > wl_output.
> 
> If it is unique to each wl_output, then it is referring to either a
> connector or a monitor, ok.
> 
> > > [...] Would xdg_outputs for the cloned wl_outputs report
> > > identical
> > > names to signify they in fact always show the exact same image?  
> > 
> > No.
> 
> This is consistent with the above, good.
> 
> > > Is this name intended to be stable and persistent, so that
> > > applications
> > > can expect to save it in a config and find the same one later,
> > > after a
> > > machine reboot, at least if the configuration of that output has
> > > not
> > > changed and the compositor is still the same version?  
> > 
> > Yes.
> 
> But if it is undefined whether the name refers to a connector or a
> monitor, would that not cause problems for apps to decide how to use
> it?
> 
> If a user unplugs one monitor and then plugs in a different monitor
> to
> the same connector, should the name change or stay the same?
> 
> If the name is defined to stay the same, the app can look at
> wl_output
> make/model to see if the monitor is different.
No, this does not work. Having multiple instances of the same make and
model is common in desktop multi-monitor setups. The app has no option
to recognize specific ones as long as there is no serial number or
other additional identifier involved that is not currently part of the
wl_output and xdg_output info.

> If the name is defined
> to change, then apps cannot target a specific connector. It obviously
> depends on apps or even users what they actually want.
> 
> If it is undefined, or if the name is defined to change in that case,
> then there is no way to reliably target a connector. Is this
> acceptable?
> 
> I would be interested too hear if you can think of why it should not
> be
> specified to refer to a connector specifically, because off-hand I
> can't imagine any reason.
> 
> Even if the name refers to a connector, a compositor could name it as
> it wishes.
> 
> > > The name is arbitrary, right? No standardization is inteneded?
> > > I.e.
> > > switching compositors will likely result in different names.  
> > 
> > Aye. Some compositors might find it useful to follow an informal
> > standard, though, like all wlroots-based compositors use consistent
> > names (e.g. DP-1).
> 
> Yeah, standardising on names would be difficult to write down right
> now.
> 
> > > Is the name enough, would you perhaps want to have a human-
> > > readable
> > > description string as well? Perhaps something for a user to
> > > totally
> > > customize and more verbose than just a name?  
> > 
> > Eh, I'm not a fan of this idea.
> 
> Very good.
> 
> > 
> > > I think it would be good to explicitly answer most of these
> > > questions
> > > in the spec, even if "configured by name" does imply some
> > > answers.  
> > 
> > Yep, will send a v3 answering some of these.
> 
> Cool.
> 
> 
> Thanks,
> pq
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