quartz/quartz/plugins/transformers/latex.ts

import remarkMath from "remark-math"
import rehypeKatex from "rehype-katex"
import rehypeMathjax from "rehype-mathjax/svg"
import { QuartzTransformerPlugin } from "../types"
import { KatexOptions } from "katex"
import { Options as MathJaxOptions } from "rehype-mathjax/svg"

interface Options {
  renderEngine: "katex" | "mathjax"
  customMacros: MacroType
  katexOptions: Omit<KatexOptions, "macros" | "output">
  mathJaxOptions: MathJaxOptions
}

interface MacroType {
  [key: string]: string
}

export const Latex: QuartzTransformerPlugin<Partial<Options>> = (opts) => {
  const engine = opts?.renderEngine ?? "katex"
  const macros = opts?.customMacros ?? {}
  return {
    name: "Latex",
    markdownPlugins() {
      return [remarkMath]
    },
    htmlPlugins() {
      if (engine === "katex") {
        return [[rehypeKatex, { output: "htmlAndMathml", macros, ...(opts?.katexOptions ?? {}) }]]
      } else {
        return [[rehypeMathjax, { macros, ...(opts?.mathJaxOptions ?? {}) }]]
      }
    },
    externalResources() {
      if (engine === "katex") {
        return {
          css: [
            {
              // base css
              content: "https://cdnjs.cloudflare.com/ajax/libs/KaTeX/0.16.9/katex.min.css",
            },
          ],
          js: [
            {
              // fix copy behaviour: https://github.com/KaTeX/KaTeX/blob/main/contrib/copy-tex/README.md
              src: "https://cdnjs.cloudflare.com/ajax/libs/KaTeX/0.16.9/contrib/copy-tex.min.js",
              loadTime: "afterDOMReady",
              contentType: "external",
            },
          ],
        }
      } else {
        return {}
      }
    },
  }
}