latex2image-web/README.md

LaTeX2Image

A Node.js web application that allows LaTeX math equations to be entered and converted to PNG/JPG/SVG images.

For each conversion, an isolated Docker container with a LaTeX installation is started; it compiles the generated .tex file and converts it to an SVG vector image. If required, the SVG file is then converted to a raster image format for PNG/JPG.

Bootstrap and jQuery are used in the web interface, with AJAX calls made to the conversion API endpoint.

Live Version

The application is accessible at https://latex2image.joeraut.com/

Dependencies

Operating system

I made use of Ubuntu 18.04. Other Linux distributions should work without problems.

Docker

Docker CE with non-root user support.

latex-docker

Docker image containing the required LaTeX packages preinstalled.

Pull the image:

docker pull blang/latex:ubuntu

Node.js

Version 6 and onwards should suffice; I made use of v10.14.2.

Global Node.js packages

svgexport

npm install svgexport -g

imagemin-cli

npm install imagemin-cli -g

Local Node.js packages

After cloning or downloading this project, run:

cd latex2image-web/
npm install

Usage

To run:

node app.js

The web interface will be accessible at http://127.0.0.1:3001 by default. The port and HTTP URL can be modified inside app.js.

Enter a LaTeX equation, for example \frac{a}{b}, and press Convert. The result will be displayed below the button.

Security

LaTeX is powerful, with the reading and writing external files and executing commands possible. It was decided a new isolated Docker container be launched for every conversion.

The container is only able to access the local temp/<id>/ directory and has no network access.

Additionally, the compilation process will be killed after 5 seconds if not complete; this is to safeguard against infinite loops and other troublesome LaTeX quirks.

Internals

Commands used:

• latex - Converts .tex source file to .dvi intermediate
• dvisvgm - Converts .dvi file to .svg vector image
• svgexport - Converts .svg to .png or .jpg raster images
• imagemin - Compresses .png and .jpg images

Notes

• The directories temp/ and output/ will be generated automatically inside the latex2image-web/ directory upon first launch.
• temp/ stores temporary .tex, .dvi, and .svg files during compilation in an inner temp/<id>/ directory, which is deleted upon completion of the conversion.
• Final output images are stored in output/, and are never deleted.

Authors

• Joseph Rautenbach - joeraut

Issues

For any issues or bugs, please submit an issue or pull request.

License

This project is licensed under the MIT License - see the LICENSE file for details.