[PATCH wayland-protocols v2 11/13] xdg-shell: clarify map/unmap wording

[Jasper St. Pierre]

Then I'd like some stronger wording in this patch that dictates that
unmapping and remapping a surface by either destroying the xdg_surface or
attaching a NULL buffer should be indistinguishable. No "hidden state",
either accessible or inaccessible to the app (such as stacking order,
window position, or user-added hints or settings) should leak through an
unmap/map cycle, if such wording hasn't been added already.

On Sun, Jul 16, 2017 at 11:32 PM, Jonas Ådahl <jadahl at gmail.com> wrote:

> On Sun, Jul 16, 2017 at 11:16:25PM -0700, Jasper St. Pierre wrote:
> > (Coming into this one late)
> >
> > When I first wrote xdg-shell, I maintained that attaching a NULL buffer
> > should be illegal since it has no benefit compared to destroying the
> > surface, but compositors might not reset all data attached to the
> surface,
> > making a weird exception where clients depend on bugs where state isn't
> > always reset. And the "resetting of all data" might seem like strange
> > behavior to clients.
> >
> > Has this rationale changed?
>
> Pretty much. It was never specified anywhere so implementations
> differed (weston and mutter implemented it like that but not sure
> anyone else did), it contradicted some wording in wayland.xml and it was
> a behaviour disliked by some, thus a middle ground was reached that
> clearly defines it as no state should be kept. I intend to try to make
> sure at least libweston-desktop and mutter respects this fully.
>
>
> Jonas
>
> >
> > On Tue, Jul 11, 2017 at 8:11 PM, David Edmundson <davidedmundson at kde.org
> >
> > wrote:
> >
> > >
> > >
> > >> The idea is that having unmapped by null-attach means the
> > >> xdg_surface/xdg_toplevel etc is reset to the exact same state that it
> > >> had when first created, thus to map again, one would do what one would
> > >> do the same as when mapping it for the first time: set up the state
> > >> (set_title, (set_maximized?), set_app_id), commit, wait for configure,
> > >> then attach a new buffer given the configure event data.
> > >>
> > >>
> > >> Thanks, I'd totally forgotten the commit as I was only looking in this
> > > interface.
> > > It's clear now.
> > >
> > > David
> > >
> > > _______________________________________________
> > > wayland-devel mailing list
> > > wayland-devel at lists.freedesktop.org
> > > https://lists.freedesktop.org/mailman/listinfo/wayland-devel
> > >
> > >
> >
> >
> > --
> >   Jasper
>



-- 
  Jasper
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