Monday, March 05, 2007

Inkscape

Creating figures in LaTeX is a pain, especially if you want to embed LaTeX in your figures. In the past I've used xfig and pstricks, which allows you to embed typeset text in a diagram, but aside from all the hoops you have to jump through (I had to massage the output files before feeding them to TeX), what you see in the GUI is uninterpreted LaTeX source. So I was always nudging things over a pixel at a time, recompiling, and checking out the PDF.

This weekend I tried Inkscape, which has a more modern UI than xfig. From what I've seen so far it's pretty nice. It comes with a plugin that allows you to input a string of LaTeX source, and it creates a shell, compiles the LaTeX source, and uses pstoedit to convert the output to SVG to import back into your diagram. It's a hack, and a little slow, but it's true WYSIWYG again.

To get it to work in cygwin I had to tweak things a bit -- one very nice thing about Inkscape is that its extensions are just python source files stuck in a directory with a naming convention, which means I could tweak the file and rerun the command (without even restarting Inkscape!) and it would reload the plugin.

I created a script /usr/local/bin/tex2svg:
#!/bin/sh

base_dir=`cygpath -wl "$1"`
base_dir=`cygpath -u "${base_dir}"`

latex_file=$base_dir/eq.tex
aux_file=$base_dir/eq.aux
log_file=$base_dir/eq.log
ps_file=$base_dir/eq.ps
dvi_file=$base_dir/eq.dvi
svg_file=$base_dir/eq.svg
out_file=$base_dir/eq.out

latex -output-directory="${base_dir}" -halt-on-error \
"${latex_file}" > "${out_file}" 2>&1
dvips -q -f -E -D 600 -y 5000 -o "${ps_file}" "${dvi_file}"

export LD_LIBRARY_PATH=/usr/lib/pstoedit:$LD_LIBRARY_PATH
pstoedit -f plot-svg -adt -ssp "${ps_file}" \
"${svg_file}" > "${out_file}" 2>&1
The file $inkscape/share/extensions/eqtexsvg.py is the plugin; I commented out the lines that call latex, dvips, and pstoedit, and replaced them with a single command:
os.system("bash --login -e tex2svg '" + base_dir + "'")
Python and LaTeX were having all sorts of problems communicating about file names with different conventions (Unix, DOS 8.3, Windows long), so I just basically punted all the work to a shell script, where I could have better control over the file names via cygpath.

To use it, go to Effects | Render | LaTeX Formula, type in a LaTeX formula, and it will magically appear (after a few external windows blip on and off). I don't understand scaling issues, especially when you're dealing with multiple file formats (.tex, .dvi, .ps, .svg), but for whatever reason I've found that sometimes I have to kill the -y 5000 in the dvips command to get the right size.

Also, when I tried saving the diagram directly to PDF, it ended up kind of blurry. I've had better luck saving it to EPS. That means that you can't use pdflatex anymore; instead you have to use dvips followed by ps2pdf. But then they seem to look okay.

4 comments:

tobo said...

That sounds useful--thanks for pointing it out.

If you have EPS figures and want to use pdflatex, you can use epstopdf to make PDF figures from the EPS figures, which pdflatex can read directly.

Doug Bradshaw said...

I just found Inkscape last week and it seems like the way to go. I've been getting Latex into Inkscape via a different route:

1. with LaTeX print a pdf including any formulas or symbols you may want in your figure. For me that just means use the draft of the paper I'm writing.

2. copy the relevant symbols to Paint, converting them to bitmaps

3. Import to Inkscape and use trace to convert from bitmap to SVG.

Thanks for posting this.

Anonymous said...

Bitmaps are RUBBISH !

Anonymous said...

The problem with inkscape->eps is that opacity is always mappedn to black. Although PDF gets it correctly, inkscape does not save the proper bounding boxes. So far I have not found any good solution.