tex2svg

#! /usr/bin/env node

/*************************************************************************
 *
 *  puppeteer/tex2svg
 *
 *  Uses MathJax v3 to convert a TeX string to an SVG string
 *  inside a headless Chrome via puppeteer.
 *
 * ----------------------------------------------------------------------
 *
 *  Copyright (c) 2020 The MathJax Consortium
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

const puppeteer = require('puppeteer');
const fs = require('fs');
const path = require('path');

//
//  The default packages to include
//
const PACKAGES = 'base, ams, newcommand, autoload, require';

//
//  Get the command-line arguments
//
var argv = require('yargs')
  .demand(0).strict()
  .usage('$0 [options] "math" > file.svg')
  .options({
    inline: {
      boolean: true,
      describe: "process as inline math"
    },
    packages: {
      default: PACKAGES,
      describe: 'the packages to use, e.g. "base, ams"'
    },
    fontCache: {
      boolean: true,
      default: true,
      describe: 'whether to use a local font cache or not'
    },
    textfont: {
      default: 'Times',
      describe: 'the font to use for text-mode material'
    }
  })
  .argv;


//
// HTML shell file (need a file:// URL so we can load other files)
//
const html = 'file://' + path.resolve(__dirname, 'puppeteer.html');

//
//  Path to MathJax root, and the component to load
//
const component = require.resolve('mathjax-full/es5/tex-svg-full.js');
const root = path.dirname(component);

//
//  Get the TeX string to process
//
const math = argv._[0] || '';

//
//  The display mode to use
//
const display = {display: !argv.inline};

//
//  The configuration to use for MathJax
//
const config = 'MathJax = ' + JSON.stringify({
  tex: {
    packages: argv.packages.replace('\*', PACKAGES).split(/\s*,\s*/)
  },
  svg: {
    mtextFont: argv.textfont,
    merrorFont: argv.textfont,
    fontCache: (argv.fontCache ? 'local' : 'none')
  },
  loader: {
    paths: {
      mathjax: `file://${root}`
    }
  },
  startup: {
    typeset: false
  }
});

//
//  Open the HTML page above in Puppeteer and use MathJax in that page
//  to convert the TeX to SVG, and print the result.
//
(async () => {
  const browser = await puppeteer.launch();       // launch the browser
  const page = await browser.newPage();           // and get a new page.
  await page.goto(html);                          // open the shell HTML page
  await page.addScriptTag({content: config});     // configure MathJax
  await page.addScriptTag({path: component});     // load the MathJax conponent
  return page.evaluate((math, display) => {       // the following is performed in the browser...
    return MathJax.startup.promise.then(() => {                      // wait for MathJax to be ready
      return MathJax.tex2svgPromise(math, display).then((m) => {     // convert TeX to svg
        return m.firstChild.outerHTML.replace(/ /g, '\&#A0;')   //   then change   to &#A0;
      });
    });
  }, math, display).then((svg) => {               // if successful:
    console.log(svg);                             //   output the resulting svg
    return browser.close();                       //   close the browser
  }).catch((e) => {                               // if there is an error:
    browser.close();                              //   close the browser
    throw e;                                      //   throw the error again (handled below)
  });
})().catch((e) => {                // If the process produces an error
  console.error(e.message);        //   reoport the error
});