Fix #1907: Support svg image in LaTeX output.

[xuhdev]

However this relies on an existing installation of inkscape. The tests of svg should be ignored if no inkscape installation is found.

[xuhdev]

This PR should solve #1907

[tk0miya]

I think endswith(('.svg', '.svgz')) is better.

[xuhdev]

Thanks, I agree with you.

[tk0miya]

It seems this is a new feature. The master branch is more appropriate to apply this PR.
Could you resend it again?

[tk0miya]

In addition, it seems enabling --shell-escape is insecure operation.
It should be better that the user specify any settings consciously (conf.py or texmf.cnf).
What do you think about the option?

[xuhdev]

@tk0miya Yes, I can add an option in conf.py. How about latex_shell_escaped = True | False(default)? I would also add an error message when svg files are included but this option is not turned on. And yes, I will resend the PR for master.

[xuhdev]

I think I have a better way to implement this without touching the --shell-escaped setting. We can convert the image format (pdf to svg for html output and svg to pdf for LaTeX output) using inkscape before generate the documents. I can reimplement these on master.

[tk0miya]

New idea looks good to me!

And, I think the feature should be implemented as sphinx extension (cf. sphinx.ext.latexsvg ).
This feature depends on inkscape. If we compose it as extension, it keeps sphinx-core simple and less dependencies.

@birkenfeld @shimizukawa What do you think about this?

[xuhdev]

@tk0miya It is more than LaTeX and svg --- it can also convert pdf/eps to svg for html output. Maybe we can call it compatible_images?

[tk0miya]

Oh, sorry. I did not noticed your comments...

It might the users can not guess what it does if it is named as compatible_images.
I think more direct words are better like 'convert'.

The naming of the extensions is very important, I think. but, at the same time, it is very difficult to get an agreements about it.
So, in this time, please name it as you like.

[xuhdev]

Thanks, I'll name it as auto_image_converter . I'll make another PR :)

[mgeier]

In case you're not aware of it, the nbconvert package has a converter using Inkscape: https://github.com/jupyter/nbconvert/blob/master/nbconvert/preprocessors/svg2pdf.py

About the name: Since it depends on Inkscape, probably it should have inkscape in its name?
Something like sphinx.ext.inkscapeconverter perhaps?