Multiple views for the same IVI surface

[Pekka Paalanen]

On Thu, 1 Oct 2015 13:27:45 +0200
Frederico Cadete <frederico at cadete.eu> wrote:

> On Thu, Oct 1, 2015 at 12:23 PM Pekka Paalanen <ppaalanen at gmail.com> wrote:
> >
> > On Thu, 01 Oct 2015 17:13:47 +0900
> > Nobuhiko Tanibata <nobuhiko_tanibata at xddp.denso.co.jp> wrote:
> >
> > > Hi,
> > >
> > > Tested-by: Nobuhiko Tanibata <NOBUHIKO_TANIBATA at xddp.denso.co.jp>
> > > Reviewed-by: Nobuhiko Tanibata <NOBUHIKO_TANIBATA at xddp.denso.co.jp>
> > >
> > > These constructors are reserved for a feature of 'a ivi-surface to
> > > several layers' and 'a ivi-layer to several screens'. This feature is
> > > required for
> > > - for example, car navigation application prepares junction guide on a
> > > surface, which shall be displayed in its own UI and cloned on
> > > instrumental cluster in another screen as well. In this case, a
> > > ivi-surface can be located in both.
> 
> I realize this is a hypothetical feature and certainly not for now, but....
> 
> I understand the need for showing the same thing in more than one screen. But
> is it sure that using the same shell surface and allowing it to be in
> more than one
> layer is the correct approach?

Hi Frederico,

Wayland allows this, that's all I can say as not an IVI person.

> The current code has properties such as destination region and
> visiblity that are part
> of the surface. These semantics are exported in ivi-layout-export.h.
> 
> I would be tempted to look into using the same wl_buffer attached to two
> wl_surfaces, but it's too much for me when I start thinking about how
> the releasing
> of the buffer would work.

That's actually a very good question:
https://bugs.freedesktop.org/show_bug.cgi?id=75303

It should work in theory, but there is some work needed to make the
semantics right.

> Maybe other shells have done this, or would be
> interested in it?
> This question would also arise if using one ivi_surface on two ivi_layers.

The difference here is: do you require the app to create a good number
of wl_surfaces with proper ivi-ids, or do you want the IVI-controller
(window manager) to be able to do it without app's explicit cooperation.

That's for the IVI architects to decide. Both ways are possible from
Wayland and Weston point of view.


Thanks,
pq

> > > However, I have to modify weston core to realize it. So, for the time
> > > being, we can remove them at this time to simplify codes.
> >
> > Hi,
> >
> > I'm not sure you need to modify Weston core. You need to create
> > one weston_view for each ivi-screen/ivi-layer/ivi-surface combination.
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