[PATCH weston] desktop-shell: do not black out with startup "none"

[Pekka Paalanen]

On Thu, 28 May 2015 14:30:25 -0500
Derek Foreman <derekf at osg.samsung.com> wrote:

> On 27/05/15 02:27 AM, Pekka Paalanen wrote:
> > On Tue, 26 May 2015 23:59:41 -0700
> > Bryce Harrington <bryce at osg.samsung.com> wrote:
> > 
> >> On Wed, May 27, 2015 at 09:48:50AM +0300, Pekka Paalanen wrote:
> > 
> >>> One thing worth to note: if Weston is using "none" background meaning
> >>> that we get undefined (garbage) content, then removing a wl_surface may
> >>> not really remove the surface's image from the screen, because there is
> >>> nothing that would make Weston to scrub it (paint over it). Therefore
> >>> no screenshooting test should ever rely on that scrubbing unless we
> >>> know there is something that enforces the image to disappear.
> >>
> >> Is there a way weston can forcibly ensure this is always zeroed when
> >> doing testing so there's no question, without burdening test writers
> >> from needing to be aware of it?
> > 
> > One way would be to set up a solid color surface beneath everything.
> > I'd hesitate to make it a test-only feature, so if it's added, it
> > should be there also in production. We could make it nice and pink, so
> > that it would reveal problems like badly rendered wallpapers.
> >
> > But I think it may need integration with the shell plugins, because the
> > shells are in charge of the scenegraph. The other option being ad hoc
> > hacking it in weston core...
> > 
> > Not sure what's best.
> 
> Is this a problem that really needs solving?

Not right now, at least.

> If a test is removing a surface then looking where the surface was, what
> could it be expecting to see?

Anything except the surface contents - but you have a point. It would
be much better to test for some known content, which means setting up
the known content in the first place.

> either something it put there (ok), or the shell (not ok because we
> don't yet have a way to wait for shell launch in a test)
> 
> So maybe the real problem that could use solving is waiting for shell
> launch.

Sure, especially for tests that will test the shell client's behaviour.

> Maybe it's useful to have the black surface be settable (a boot logo or
> something) instead of black - but that's a different problem altogether.  :)

Boot logo things are likely best done by Plymouth kind of things, I
think. No need for Weston to have its own. What Weston is missing,
though, is scraping the old fb and using that to make a cross-fade onto
the desktop. The implementation could be as simple as putting the
scraped image on the currently black fade-in surface. Well, not that
simple because it needs to be per output and...


Thanks,
pq