Fwd: Fwd: Is `org-preview-latex-fragment` sensitive to alignment specified by document class options?

[Rob Stewart <robstewart57@gmail.com>]

Maybe a spoke too soon. My answer below is partly the case. When I
turn on latexpreview with `#+STARTUP: latexpreview` then my formula is
laid out the way I intend, i.e.:
http://imgur.com/eMrwiIJ

Strangely, however, when I hit C-c C-c to remove the preview, then run
`org-preview-latex-fragment` by hand, I see:
http://imgur.com/qznnKj3

Having read through the the org-mode derived mode, me stating
`#+STARTUP: latexpreview` in my org mode triggers a call to
`org-preview-latex-fragment` in org.el:

--8<---------------cut here---------------start------------->8---
     (when org-startup-with-latex-preview
       (org-preview-latex-fragment))
--8<---------------cut here---------------end--------------->8---

So, what is happening between this call at startup, and me later
calling `org-preview-latex-fragment` by hand after org-mode has been
fully loaded? I have tried locating the temporary tex file that gets
generated with this call. But when `org-preview-latex-fragment is
called without errors, I cannot locate the temporary file?

--
Rob

---------- Forwarded message ----------
From: Rob Stewart <robstewart57@gmail.com>
Date: 19 April 2014 14:02
Subject: Re: [O] Fwd: Is `org-preview-latex-fragment` sensitive to
alignment specified by document class options?
To: Nick Dokos <ndokos@gmail.com>, emacs-orgmode@gnu.org


Hi Nick,

Thanks for guiding me to a solution, which was to write write my own
defcustom `my-org-format-latex-header`, changing the first line from
the definition in org.el to "\\documentclass[fleqn]{article}". This
definition I call `my-org-format-latex-header`. I then redefine
`org-create-formula--latex-header` to use
`my-org-format-latex-header`, as so:

--8<---------------cut here---------------start------------->8---
(defcustom my-org-format-latex-header "\\documentclass[fleqn]{article}
\\usepackage[usenames]{color}
\[PACKAGES]
\[DEFAULT-PACKAGES]
\\pagestyle{empty}             % do not remove
% The settings below are copied from fullpage.sty
\\setlength{\\textwidth}{\\paperwidth}
\\addtolength{\\textwidth}{-3cm}
\\setlength{\\oddsidemargin}{1.5cm}
\\addtolength{\\oddsidemargin}{-2.54cm}
\\setlength{\\evensidemargin}{\\oddsidemargin}
\\setlength{\\textheight}{\\paperheight}
\\addtolength{\\textheight}{-\\headheight}
\\addtolength{\\textheight}{-\\headsep}
\\addtolength{\\textheight}{-\\footskip}
\\addtolength{\\textheight}{-3cm}
\\setlength{\\topmargin}{1.5cm}
\\addtolength{\\topmargin}{-2.54cm}"
  "The document header used for processing LaTeX fragments.
It is imperative that this header make sure that no page number
appears on the page.  The package defined in the variables
`org-latex-default-packages-alist' and `org-latex-packages-alist'
will either replace the placeholder \"[PACKAGES]\" in this
header, or they will be appended."
  :group 'org-latex
  :type 'string)

(defun org-create-formula--latex-header ()
  "Return LaTeX header appropriate for previewing a LaTeX snippet."
  (let ((info (org-combine-plists (org-export--get-global-options
  (org-export-get-backend 'latex))
 (org-export--get-inbuffer-options
  (org-export-get-backend 'latex)))))
    (org-latex-guess-babel-language
     (org-latex-guess-inputenc
      (org-splice-latex-header
       my-org-format-latex-header
       org-latex-default-packages-alist
       org-latex-packages-alist t
       (plist-get info :latex-header)))
     info)))
--8<---------------cut here---------------end--------------->8---

Now when I call `org-preview-latex-fragment`, the math is correctly
rendered in emacs:
http://imgur.com/mMrMIE6

My only question is: rather than using `defcustom` to define
`my-org-format-latex-header` (hence needing to redefine
`org-create-formula--latex-header`, how do I simply override the
existing definition for `org-format-latex-header`? A hasty attempt to
use setq threw the following backtrace:

--8<---------------cut here---------------start------------->8---
Debugger entered--Lisp error: (wrong-type-argument symbolp "The
document header used for processing LaTeX fragments.
It is imperative that this header make sure that no page number
appears on the page.  The package defined in the variables
`org-latex-default-packages-alist' and `org-latex-packages-alist'
will either replace the placeholder \"[PACKAGES]\" in this
header, or they will be appended.")
  (setq org-format-latex-header "\\documentclass[fleqn]{article} ..
  eval-last-sexp-1(nil)
  eval-last-sexp(nil)
  call-interactively(eval-last-sexp nil nil)
--8<---------------cut here---------------end--------------->8---

Thanks Nick!

--
Rob

On 9 April 2014 18:22, Nick Dokos <ndokos@gmail.com> wrote:
> Rob Stewart <robstewart57@gmail.com> writes:
>
>>
>> I asked the question below a few days ago, about whether
>> `org-preview-latex-fragment` is sensitive document class options that
>> might affect alignment. I've so far not received feedback, and
>> wondered whether there is more information that I could provide, or if
>> my question is not interesting to other people :-)
>>
>> ....
>>
>> Is there a way to make `org-preview-latex-fragment` sensitive to LaTeX
>> class options? I have a simple example to demonstrate where it does
>> not:
>>
>> %%%%%%% #+LaTeX_CLASS: article #+LaTeX_CLASS_OPTIONS: [fleqn]
>> #+LATEX_HEADER: \usepackage{amsmath}
>>
>> \begin{gather} b := (a \oplus s_1) \oplus s_2 \\ e := 0 \\
>> \end{gather} %%%%%%%
>>
>> If LaTeX is generated for this document with
>> `org-latex-export-to-latex`, which is compiled to a PDF with pdflatex,
>> the "b :=" and the "e :=" are left aligned i.e. the "b" and "e" are
>> vertically aligned.
>>
>> However, if `org-preview-latex-fragment` is called within emacs, the
>> left alignment specified with the `[fleqn]` class option is not
>> honoured. Thus, the two lines in the `gather` block are centrally
>> aligned, which is the default case for `gather` blocks.
>>
>
> org-preview-latex-image is its own self-contained universe and has very
> little in common with latex exporting. In particular, the preview
> preamble is generated by calling org-create-formula--latex-header. Try
> evaluating a call to the function in your *scratch* buffer and see what
> it gives you - I get:
>
> ,----
> | (org-create-formula--latex-header)
> | "\\documentclass{article}
> | \\usepackage[usenames]{color}
> | % Package minted omitted
> | \\usepackage[utf8]{inputenc}
> | \\usepackage[T1]{fontenc}
> | % Package fixltx2e omitted
> | \\usepackage{graphicx}
> | % Package longtable omitted
> | % Package float omitted
> | % Package wrapfig omitted
> | % Package rotating omitted
> | \\usepackage[normalem]{ulem}
> | \\usepackage{amsmath}
> | \\usepackage{textcomp}
> | \\usepackage{marvosym}
> | \\usepackage{wasysym}
> | \\usepackage{amssymb}
> | % Package hyperref omitted
> | \\tolerance=1000
> | \\pagestyle{empty}             % do not remove
> | % The settings below are copied from fullpage.sty
> | \\setlength{\\textwidth}{\\paperwidth}
> | \\addtolength{\\textwidth}{-3cm}
> | \\setlength{\\oddsidemargin}{1.5cm}
> | \\addtolength{\\oddsidemargin}{-2.54cm}
> | \\setlength{\\evensidemargin}{\\oddsidemargin}
> | \\setlength{\\textheight}{\\paperheight}
> | \\addtolength{\\textheight}{-\\headheight}
> | \\addtolength{\\textheight}{-\\headsep}
> | \\addtolength{\\textheight}{-\\footskip}
> | \\addtolength{\\textheight}{-3cm}
> | \\setlength{\\topmargin}{1.5cm}
> | \\addtolength{\\topmargin}{-2.54cm}"
> `----
>
> As you can see both the document class and the class options (none)
> are hardwired.
>
> The function looks like this
>
> ,----
> | (defun org-create-formula--latex-header ()
> |   "Return LaTeX header appropriate for previewing a LaTeX snippet."
> |   (let ((info (org-combine-plists (org-export--get-global-options
> |                                  (org-export-get-backend 'latex))
> |                                 (org-export--get-inbuffer-options
> |                                  (org-export-get-backend 'latex)))))
> |     (org-latex-guess-babel-language
> |      (org-latex-guess-inputenc
> |       (org-splice-latex-header
> |        org-format-latex-header org-latex-default-packages-alist
> |        org-latex-packages-alist t (plist-get info :latex-header)))
> |      info)))
> `----
>
> so in order to add class options you have to redefine the variable
> org-format-latex-header. But whatever you set them to, they will be
> hardwired: there is no way to propagate a setting from the org
> file.
>
> Nick
>
>
>
>