Re: Built-in HTML parsing and rendering library

[Ted Zlatanov <tzz@lifelogs.com>]

On Mon, 06 Sep 2010 14:28:10 +0200 Lars Magne Ingebrigtsen <larsi@gnus.org> wrote: 

LMI> Ted Zlatanov <tzz@lifelogs.com> writes:
>> It's what Gnome uses so it's pretty good.  Because of the Gnome link it
>> would probably be the easiest one to bring into the Emacs core.

LMI> Yes.  I had a quick peek at the interface, and it seemed to return a
LMI> nice DOM that could probably be exported to Emacs pretty easily as an
LMI> elisp list tree like (:html (:head ...) (:body ...)) etc.

HTML and XML are SGML which is a crappy Lisp, so yeah :)  Parsing them
with libxml2 would improve many corners of Emacs.

LMI> And since libxml2 is already installed on 99% of Linux machines, linking
LMI> Emacs to it should be no big deal.

Yes.  The patch would be small.  I don't know if the Emacs maintainers
will have objections but it's kind of weird no one has proposed it yet.

LMI> So the question is: If we have the parse tree in Emacs Lisp, would we be
LMI> able to render it quickly enough for it to make sense to use?  I haven't
LMI> really thought about it much, but it strikes me that rendering heavily
LMI> nested tables and the like might be a time-consuming task in a language
LMI> that's as slow as Emacs Lisp.  But it might be fine; I'm not sure at all.

LMI> Is there a component of libxml2 (or some other handy library) that does
LMI> HTML rendering, too?  :-)

These days Mozilla's Gecko is getting less popular.  http://webkit.org/
is really popular and it's LGPL.  I know it's been proposed for Emacs
inclusion before and I think it's just been general laziness not to
include it.

IMO this is a really deep hole than is measured in man-years of work.
HTML parsing is easy; rendering it is a nightmare compounded by years of
legacy crap.  So I am pessimistic this is a good use of your time.  If
the Emacs project took interest in this, there would be many more
hackers and users available and it could happen.  Or it could all
devolve into endless arguments about keyboard stickers and DVCS supremacy.

Ted