Re: Ligatures

[Eli Zaretskii <eliz@gnu.org>]

> Date: Tue, 19 May 2020 17:18:41 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: pipcet@gmail.com, emacs-devel@gnu.org
> 
> > From: ASSI <Stromeko@nexgo.de>
> > Cc: pipcet@gmail.com,  emacs-devel@gnu.org
> > Date: Tue, 19 May 2020 07:43:00 +0200
> > 
> > The only program I ever used that I remember doing this (a WYSIWYG TeX
> > editor for DOS, natch) temporarily broke the ligature while you were
> > moving the cursor inside.  It looked a bit strange and was slightly
> > distracting if you were just moving the cursor without trying to edit
> > it, but otherwise did the job well.
> 
> That's what I had in mind (although I never used such an editor).

Btw, there's one subtle issue that will need to be resolved if we are
to have this feature of "sub-glyph" cursor movement inside composed
characters.  The way we currently display the default block cursor is
by simply redrawing the glyph at point in reverse video.  So we don't
have a way of displaying a cursor that "covers" only part of a glyph.
To make this happen, we'd probably need to draw the cursor as part of
drawing the glyph foreground and/or background, which is against the
current flow of the display code: we generally first completely draw
the background and foreground of the entire text that needs to be
redrawn, and only then draw the cursor where it should be placed.

Something to figure out by that "Someone" who'd volunteer for the job.