WebTeX Render

Render Pandoc's `--webtex` to local images

About the project

WebTeX Render is a simple program used to generate static images from LaTeX equations. It was designed to be used as an alternative to https://latex.codecogs.com/. It also allows you to use arbitrary LaTeX packages in your images.

We also provide a simple web API to generate images on demand.

Usage

# 1. Convert pandoc document to HTML
pandoc input.md -s --webtex='eqn://' -o pandoc.html

# 2. Generate WebTeX images
./wr -input pandoc.html -output final.html -template template.tex

# Or using one-liner: 
pandoc input.md -s --webtex='eqn://' -t html | ./wr -output final.html -template template.tex

When using Pandoc's standalone mode (-s), we recommend using the following CSS to align inline equations:

img.math.inline {
    vertical-align: bottom !important;
}

Using the web API

The webtex_web requires a configuration file to define "renderers".

- name: render_name
  key: secret
  template: template.tex

The TeX image can be then generated at URL http://...:8080/render/render_name/?eq=EQUATION&sig=SIGNATURE. EQUATION should be a base64 encoded TeX. SIGNATURE should be a HMAC-SHA-256 of the EQUATION using the key from config.

Minimal template

\documentclass{standalone}

\usepackage{scrextend}
\changefontsizes{16pt}

\begin{document}
\strut{}${{ .Equation }}$
\end{document}

We have changed the font size to 16pt as this is the default on web. We have also added \strut{} at the start of the document to make sure that all output files are at least 1em high.

Building

go build -o wr ./webtex_render
go build -o wr_web ./webtex_web

Docker image

We also provide a Docker image. The image contains both wr and wr_web binaries, but is set up to start the web API by default.

docker run --rm \
  -v ./config.yml:/app/config.yml:ro \
  -v ./template.tex:/app/template.tex:ro \
  -p 8080:8080 \
  ghcr.io/naboj-org/webtex_render