Re: Lazy image converters

[Lars Ingebrigtsen <larsi@gnus.org>]

Evgeny Zajcev <lg.zevlg@gmail.com> writes:

> What if we have a lazy image, so its FILE-OR-DATA is calculated at
> redisplay time.  'image-convert' could utilize this.  One of the
> approaches to lazy images is to allow FILE-OR-DATA to be a function
> returning actual file or data.  Redisplay could call this func and
> substitute the value of FILE-OR-DATA in image spec with the results,
> kind of caching the results.

Hm...  It does sound nice, but I worry about calling this complicated
(and slow) code from redisplay.

And in my experience, most of the time when you put images in a buffer,
you're going to display them, so it's not clear that this would often be
a win, UX wise.

I can see it being so when preparing huge directory-like buffers (with
images; I do that for my music playing interface) -- then the user will
normally only display a small subsection of the images, and then
delaying the processing of the images is a win.

And the same is the case for web pages, I guess, but there the download
time dwarfs anything Emacs does, so it wouldn't make much difference
there, I think?

So...  I'm not convinced of the utility here, especially compared to the
potential problems arising from running complicated Lisp code from
redisplay.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no