Re: Question about display engine

[Ergus]

On Wed, Aug 28, 2019 at 08:24:26PM +0300, Eli Zaretskii wrote:
> > Date: Wed, 28 Aug 2019 18:31:42 +0200
> > From: Ergus <address@hidden>
> > Cc: Eli Zaretskii <address@hidden>, address@hidden
> >
> > Any way my question comes from 2 frequent use cases I don't know what's
> > the expected behavior:
> >
> > 1) Base face sets background and extend; and face sets only background.
>
> The background of the base face will be extended.

But AFAIU the actual merging rules now will create a new face (if not
there already) that will have the new background; so this means that
then we need a way to remember the last background color where
background and extend where set at the same time; so the extend flag
will be not a bool flag, but a pointer (or a copy) to a previous point
(value) in the faces stack??

Then at the last step of the merge we could potentially have N exact
equal faces that only have difference in those points.

> > 2) Base face sets extend but not background; and face sets both.
>
> The background of the face will be extended.
>
> > in what condition the :extend attribute goes to the merged face? Always?
> > when in base_face? When in face?
>
> The :extend attribute determines whether the background color of the
> face with that attribute does or doesn't get merged into the "merged
> face" to be used by the iterator.