Re: using glyphs by default in perl-mode

[Ted Zlatanov <tzz@lifelogs.com>]

On Wed, 05 Jun 2013 12:13:00 -0400 Stefan Monnier <monnier@IRO.UMontreal.CA> wrote: 

>> I also thought about `put-text-property' of an image but that's pretty
>> ugly and special-cases all the code, plus it has update issues in some
>> cases (deleting characters and reinserting them doesn't trigger the
>> image again).  It would be really nice to be able to use
>> `compose-region' and use an image to create a glyph.  For now it's a
>> TODO but I think it would be a hit with users.  If anyone is interested
>> or wants to tell me how it could work, let me know.

SM> I think this is pushing it "too far": I'm not opposed to such a feature
SM> in general, but I'm not sure it would benefit much from sharing some
SM> code with the current prog-prettify code.

OK.  I'll shelve/stash it for now.

SM> BTW, one problematic part with the use of images is when you need to
SM> scale them to fit the text's size.

Of course.  I was thinking of a dynamically produced glyph that scales
down to the text size.  I think SVG can do something like that, scaling
gracefully.  If you want a bigger image, you increase the font size!

Currently images don't respect the text size which makes them mostly
unusable in serious editing.

>> The other TODO item is to simplify this support so it doesn't require
>> special effort when setting `font-lock-defaults'.  I don't know how that
>> would work internally so I'll wait for Stefan or someone else to give me
>> hints or implement it.

SM> I think the best way to do that is going to be to provide a function
SM> that uses font-lock-add-keywords internally.  That function might even
SM> take the symbols-alist as argument and do the (setq-local
SM> prog-prettify-alist..) itself, so major modes can just call
SM> (prog-prettify '(("=>" . ?⇒))).

That would be best.  I'll look into it.

Ted