Re: High-res Customize icons

[Richard Stallman]

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  > That's not exactly why I asked whether it's a good idea.  I'm asking
  > whether it's a good idea to use characters as if they were small
  > images.

Could you state the issue more clearly?  In an abstract sense, a glyph
IS a small image.  You know that, so I suppose you refer to some more
specific, concrete issue, perhaps related specifically to how Emacs
redisplay works?

Could you please spell out that issue?

             That is not what fonts were designed for,

If lots of programs use fonts for that job, I think we can
conclude their design is suitable for it.

                                                       and that is
  > definitely not what font-selection code in Emacs was designed for.

That could be an important issue.  I think it would depend on
just where Emacs would display the images, and for what purpose.

If they would appear within lines of text, I think it would not be
hard to change Emacs to display them more or less as if they were
characters.  That doesn't mean they have to be like characters at the
level of strings or buffers.

However, if they are not like characters at that level, we would
need to design some other Lisp-level spec for them.

  > > To conform to the standard, glyphs that are not in Unicode would be
  > > put into the PUA (Private User Area), again ensuring that there are no
  > > conflicts with other applications.

At what levels in the code of Emacs would it be necessary to use the PUA?

Would this be limited to communication with other components of the
operating system, such as Xlib or GTK?  If so, I think it would not
be a problem for Emacs to do this, if it is commonplace for other
programs to do this.

Or would this have to extend up into other levels of Emacs?

  > I'm very much against using PUA codepoints for this purpose (or any
  > purpose, really) in Emacs.

Could you explain?

                                To say nothing of the fact that we
  > currently simply cannot.  That's a non-starter, from my POV.

What is the obstacle?  I think the key question is which levels of
Emacs the obstacle applies to.  Would the obstacle preclude using PUA
characters for low-level communication with Xlib or comparable
libraries?  If not, maybe we could represent the icons and emojis
some other way at higher levels.

It might be ok to do this with image files, but before rejecting the
idea of doing this with fonts, let's look at it carefully.

-- 
Dr Richard Stallman
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)