Exporting all equations from a document as individual svg files

Question

I'm currently a presentation based on a paper originally written in Latex. Currently, I use Kile and Ubuntu for my work.

What I'm finding is that I need a large number of the equations from the original paper scattered around the presentations (and are using them to annotate diagrams etc). My current method of screenshots + gimp is rather slow :)

So, what I would like to do is compile the tex document and instead of creating a pdf/dvi, I would like it to spit out a number of files, which each file being one of the equations from the document, preferably in a vector format, but I will live with a PNG if I have to, so long as it's of high enough resolution.

I've had a look at a number of utilities.

The following web utility: http://www.codecogs.com/latex/eqneditor.php does more or less what I want for an individually typed equation. However, I've used a lot of mactros in equations that make it a little messy to use (for example)

\newcommand{\SkewSymmetric}[1]{\ensuremath{ \left[ #1 \right]_{\times}}}

I've had a look at pdf2svg, but it doesn't quite do what I want - I still need to crop out the equation of interest.

Is there anything else I should look at?

Answer 1

Check out the preview package. E.g., including

\usepackage[active,tightpage]{preview}
\PreviewEnvironment{equation}

prints all equation environments and nothing else, each cropped, one to a page. It's equally effective with DVI and pdf output. Embedded macros in equation (or whatever) environments are handled transparently and properly.

The pdf can then be converted to SVG images with the following command:

pdf2svg filename.pdf output-page%03d.svg all

Answer 2

To extend the answer from @Kilgore:

To get rid of the equation numbers (AND you have an excellent backup of the original file(s)!), yon can do the following:

#!/bin/bash

files=`find . | grep -e '\.tex$'`

for file in $files ; do 

    echo "Stripping: $file"

    # Create a copy of the existing file
    cp $file $file.strip_backup

    sed -i 's/begin{equation\*}/begin{align*}/g'   $file
    sed -i 's/end{equation\*}/end{align*}/g'   $file

    sed -i 's/begin{equation}/begin{align*}/g'   $file
    sed -i 's/end{equation}/end{align*}/g'   $file

    sed -i 's/begin{align}/begin{align*}/g'   $file
    sed -i 's/end{align}/end{align*}/g'   $file

done

The individual equations can be extracted using:

\usepackage[active,tightpage]{preview}
\PreviewEnvironment{align*}

(Note the addition of the *)

To remove the excessive whitespace, use the following utility:

pdfcrop output.pdf

And, finally, you can split this into individual svg files

mkdir output-equations
pdf2svg filename.pdf output-equations/output-page%03d.svg all

If the svg images are still not properly cropped, Inkscape can fix that:

inkscape -z --verb=FitCanvasToDrawing --verb=FileSave --verb=FileClose output-equations/*.svg

Answer 3

Make a Metapost file with one figure per equation, with each equation in an "unboxed box":

beginfig(1)
  boxit.a(btex $$e^{i\pi}+1=0$$ etex);
  a.c = (0,0);
  drawunboxed(a);
endfig(1);

beginfig(2)
  boxit.a(btex $$F={G m_1 m_2 \over d^2}$$ etex);
  a.c = (0,0);
  drawunboxed(a);
endfig(2);

Run mptosvg, which will generate one SVG file per figure, with the right bounding boxes.

Answer 4

\documentclass{article}
    \usepackage[active,tightpage]{preview}
    \usepackage{amsmath}

    \pagestyle{empty}

\begin{document}
    \begin{equation}
        1-\strut\displaystyle\frac{2\,M}{r}, \quad \text{for}\, r>R,
    \end{equation}

    foo $ xy=f(x) $ bar

    foo \[ dy=g(x) \] bar
\end{document}

Latex to SVG cmd

$latex test.tex
$dvisvgm.exe -n -p 1-5 -c 1.2,1.2 test.dvi

Answer 5

You can also use ltximg package, which uses the preview package internally but also crops the generated fragments and converts them to many different formats. You could use @Damien's answer above to convert all math environments into align*'s and call:

ltximg --latex --extrenv 'align*' --imgdir eqs --svg --png -o test-out test_eq.tex

to get pdf, svg and png fragments extracted from test_eq.tex into eqs directory. ltximg by default extracts only picture environments (tikz, pstricks, etc.), so we need to use --extrenv to specify math environments.