Re: Implementing child frames on terminal

[Eli Zaretskii]

> From: Akib Azmain Turja <akib@disroot.org>
> Cc: Eli Zaretskii <eliz@gnu.org>, monnier@iro.umontreal.ca,
>  emacs-devel@gnu.org, ibluefocus@outlook.com
> Date: Tue, 12 Jul 2022 14:35:31 +0600
> 
> > Fixing that (assuming you clip the contents of the child frame to the
> > parent) sounds easier than what you propose further on here:
> >
> >> I think we should somehow render the child frame glyph matrix before
> >> processing it's parents.  Then we can copy the it's glyph matrix to it's
> >> parent's one.  And, in case the child frame doesn't cross parent's
> >> edges, we can use a floating window (as you suggested) as an
> >> optimization (although I don't think we need this optimization, since
> >> terminal don't usually have many characters).
> 
> Really?  It looks like it would require to modify whole redisplay logic
> to make sure whether a glyph is inside edges and write to it only if it
> is.

Actually, the current redisplay code does this all the time: that's
how we know when to continue or truncate a too-long line, or where to
wrap a long line under visual-line-mode.