Re: Question on latex source block

[Eric Schulte <eric.schulte@gmx.com>]

Nick Dokos <nicholas.dokos@hp.com> writes:

> Eric Schulte <eric.schulte@gmx.com> wrote:
>
>> >
>> > Nothing - it's a bug introduced by commit a9d3ce0bcd3492eb0cd2aa7b0d1f6ee93276114b:
>> >
>> > ,----
>> > | commit a9d3ce0bcd3492eb0cd2aa7b0d1f6ee93276114b
>> > | Author: Feng Shu <tumashu@gmail.com>
>> > | Date:   Fri Apr 20 19:21:43 2012 +0200
>> > | 
>> > |     Allow to use imagemagick for previewing LaTeX fragements.
>> > |     
>> > |     * org.el (org-latex-create-formula-image-program): New option
>> > |     to use either dvipng or imagemagick to convert and preview
>> > |     LaTeX fragments.
>> > |     (org-preview-latex-fragment, org-format-latex): Handle the new
>> > |     option.
>> > |     (org-create-formula-image-with-dvipng): Rename from
>> > |     `org-create-formula-image'.
>> > |     (org-create-formula-image-with-imagemagick): New defun to
>> > |     handle LaTeX preview with imagemagick.
>> > |     (org-latex-color, org-latex-color-format): New defuns to
>> > |     handle color conversions.
>> > |     
>> > |     * org-latex.el (org-latex-to-pdf-process, org-export-as-pdf):
>> > |     Allow to use imagemagick to convert LaTeX fragments.
>> > |     
>> > |     * org-html.el (org-export-html-preprocess): Ditto.
>> > |     
>> > |     * org-exp.el (org-export-with-LaTeX-fragments): Ditto.
>> > |     
>> > |     * org.texi (@LaTeX{} fragments): Document imagemagick as an
>> > |     alternative to dvipng.
>> > | 
>> > `----
>> >
>> > org-create-formula-image got renamed, but the reference in ob-latex.el
>> > to the original name was not changed.
>> >
>> > The quick-and-dirty "fix" is to change the reference in ob-latex.el to
>> > org-create-formula-image-dvipng or org-create-formula-image-imagemagick,
>> > depending on which method you happen to be using. But one would resort
>> > to that only in the direst emergency in order to get something working
>> > as quickly as possible.
>> >
>> > IMO, it would be better to have split the dvipng/imagemagick decision at
>> > a lower level in the code. That way, both org-format-latex and
>> > org-babel-execute:latex would use the common function. As it is,
>> > org-format-latex is a fairly "dirty" function and with the split, it got
>> > even dirtier.
>> >
>> > But there may be difficulties that my quick glance through the code has
>> > not uncovered: it needs a deeper look.
>> >
>> 
>> So, what would you recommend as a full fix in ob-latex.el?  The attached
>> commit selects an alternate function based on the value of the
>> `org-latex-create-formula-image-program' variable.  Does this seem like
>> an appropriate fix to the problem?
>> 
>
> For the time being, yes: I think this fix is entirely appropriate (nb:
> haven't tested it yet though).
>
> In the longer run, I would like to see a single function
> (org-create-formula-image redux) be called from the two call sites
> (org-format-latex and org-babel-execute:latex) and have the
> dvipng/imagemagick/etc split be entirely within that function. It's
> bound to happen that more methods of creating images (the etc part
> above) will need to be added in the future and it behooves one to
> arrange it so that only one place in the code is affected.
>
> Thanks,
> Nick
>

Alright,

I've just committed a patch which gets part-way to your suggest
solution.  While the two backend-specific functions are still separate
(I agree they should be combined), I have brought back the
`org-create-formula-image' function, which now dispatches to the backend
specific functions.

Additionally there are some problems in the `org-format-latex' function.
It lists mandatory arguments as optional, and appears to create
variables which are not required or properly set.

These function should probably be cleaned at some point up by whoever is
maintaining Org-mode's LaTeX interfaces.

Cheers,

-- 
Eric Schulte
http://cs.unm.edu/~eschulte