Re: Foreground color opacity

[Filippo Argiolas <filippo.argiolas@gmail.com>]

On Mon, Sep 11, 2023 at 2:59 PM Eli Zaretskii <eliz@gnu.org> wrote:
>
> > From: Filippo Argiolas <filippo.argiolas@gmail.com>
> > Date: Mon, 11 Sep 2023 12:45:04 +0200
> >
> > My approach so far has been something like this:
> > - label inactive regions with a dedicated text property
> > - add a function that runs after fontify-lock-fontify-region-function
> > (after so we run when we have fortified text with font lock faces)
> > - inside the fontify function detect face changes in the inactive
> > region and for each different face encountered apply a new one with
> > foreground color computed blending current foreground and background
> >
> > It seems to work so far and I like the result, but I keep thinking
> > it's overly complicated for something so simple as setting text
> > opacity. I'm pretty new to emacs lisp, am I missing a face attribute I
> > can just set in an overlay and get the same result? Wouldn't it make
> > sense to have something like this at backend level if it doesn't exist
> > yet?
>
> Why not cover the "inactive" portion with an overlay which has the
> 'face' (or font-lock-face) property that specifies only the opacity?
> That is IMO simpler and doesn't need to run any functions after
> fontifications.
>
> (Caveat: I didn't actually try this approach, so maybe I'm missing
> something.)
>
> Thanks.

That would be the perfect solution, but as far as I can tell we don't
have an opacity face attribute, do we?

Filippo