Re: image scaling

[Richard Stallman <rms@gnu.org>]

    My main concern with outsourcing particular bits of the Emacs image
    functionality to external libraries (which may or may not be linked
    in) is how this will look at the Lisp level.

The natural and convenient way is to put something in the text
properties that specify scaling, etc.  That makes it very easy
for Lisp programs to specify scaling.

      But it
    would be a mess if we force users (Lisp coders) to perform a similar
    test before performing things like image rescaling---or, worse still,
    having such functionality quietly disappear, by functions not being
    defined or becoming no-ops.

The tremendous advantage of using library facilities for this
outweighs that disadvantage.

We should not write our own "fallback" code, because that is
duplication of effort.  Let's use the libraries to save our time so we
can make some other improvement.

    As for refactoring the Emacs image code, I'm not sure if there's any
    urgency for such a project.  The code isn't elegant, but it's simple
    enough to understand and work on; and I don't know of any performance
    problem in the way Emacs handles image pixmaps.

I agree it is not urgent, but it is quite desirable.
We could release Emacs 23 without doing this, but we would very
much like someone to do it after that.