How many degrees of headlessness do we need?

[Riccardo Magliocchetti]

Il 29/03/2015 08:21, Tor Lillqvist ha scritto:
> As far as I see, we have the following command-line options or other ways to
> avoid display of GUI elements:
[snip]
> - The --invisible switch. Not much used? Exact semantics unknown. What is the
> intended interaction with existing LibreOffice instances, is there the normal
> IPC pipe thing going on, so that only one LO instance runs per user session?

Looking at the code there's quite a lot of if that avoid calling 
OfficeIPCThread::ExecuteCmdLineRequests when libo is invoked with --invisible
Telepathy has some knowledge of it for some reason.

> - The --headless switch. Perhaps newer than --invisible? Not sure why a separate
> one is needed and what the exact intended semantics are. Again, how is it
> supposed to affect the interaction with other LibreOffice instances?
>
> On Linux (and other X11-using Unixes), --headless is tightly coupled to the
> 'vclplug' concept, as there used to be a 'headless' (actually called 'svp')
> vclplug that was used (instead of a "generic" X11, GTK or KDE one) in headless
> mode. Nowadays the 'svp' code is not technically a vclplug any more, but that is
> just an implementation detail. On Windows and OS X, --headless support is
> presumably broken to some degree.
>
[snip]
>
> This is a mess and needs clarification. There are five modes of headlessness. Do
> these modes form a hierarchy? Or is it possible, and meaningful, to have a
> LibreOffice instance that is headless but not invisible, for instance? Could we
> at least finally kill the quick start concept, which surely is outdated by now?

I've googled a bit on libreoffice headless and invisible options usage on forums 
in the context of document conversion. Found just once occurence of invisible 
used alone at stack overflow, most of the time it's headless alone or headless 
and invisible together. So i'd just make it an alias of headless to avoid 
breaking scripts and mark it as deprecated in the help.

thanks

-- 
Riccardo Magliocchetti