@rpidanny/pdf2md/lib/util/pdf.js

A PDF to Markdown Converter

const path = require("path");
const pdfjsPromise = import("pdfjs-dist/legacy/build/pdf.mjs");

pdfjsPromise.then((pdfjs) => {
  pdfjs.GlobalWorkerOptions.workerSrc = `pdfjs-dist/legacy/build/pdf.worker.mjs`;
});

const {
  findPageNumbers,
  findFirstPage,
  removePageNumber,
} = require("../../lib/util/page-number-functions");
const TextItem = require("../models/TextItem");
const Page = require("../models/Page");

const NO_OP = () => {};

exports.parse = async function parse(docOptions, callbacks) {
  const { metadataParsed, pageParsed, fontParsed, documentParsed } = {
    metadataParsed: NO_OP,
    pageParsed: NO_OP,
    fontParsed: NO_OP,
    documentParsed: NO_OP,
    ...(callbacks || {}),
  };
  const fontDataPath = path.join(
    path.resolve(require.resolve("pdfjs-dist"), "../../standard_fonts"),
    "/"
  );
  if (typeof docOptions === "string" || docOptions instanceof URL) {
    docOptions = { url: docOptions };
  } else if (
    docOptions instanceof ArrayBuffer ||
    ArrayBuffer.isView(docOptions)
  ) {
    docOptions = { data: docOptions };
  }
  const pdfjs = await pdfjsPromise;
  const pdfDocument = await pdfjs.getDocument({
    ...docOptions,
    standardFontDataUrl: fontDataPath,
  }).promise;
  const metadata = await pdfDocument.getMetadata();
  metadataParsed(metadata);

  const pages = [...Array(pdfDocument.numPages).keys()].map(
    (index) => new Page({ index })
  );

  documentParsed(pdfDocument, pages);

  const fonts = {
    ids: new Set(),
    map: new Map(),
  };

  let pageIndexNumMap = {};
  let firstPage;
  for (let j = 1; j <= pdfDocument.numPages; j++) {
    const page = await pdfDocument.getPage(j);
    const textContent = await page.getTextContent();

    if (Object.keys(pageIndexNumMap).length < 10) {
      pageIndexNumMap = findPageNumbers(
        pageIndexNumMap,
        page.pageNumber - 1,
        textContent.items
      );
    } else {
      firstPage = findFirstPage(pageIndexNumMap);
      break;
    }
  }

  let pageNum = firstPage ? firstPage.pageNum : 0;
  for (let j = 1; j <= pdfDocument.numPages; j++) {
    const page = await pdfDocument.getPage(j);

    // Trigger the font retrieval for the page
    await page.getOperatorList();

    const scale = 1.0;
    const viewport = page.getViewport({ scale });
    let textContent = await page.getTextContent();
    if (firstPage && page.pageIndex >= firstPage.pageIndex) {
      textContent = removePageNumber(textContent, pageNum);
      pageNum++;
    }
    const textItems = textContent.items.map((item) => {
      const tx = pdfjs.Util.transform(viewport.transform, item.transform);

      const fontHeight = Math.sqrt(tx[2] * tx[2] + tx[3] * tx[3]);
      const dividedHeight = item.height / fontHeight;
      return new TextItem({
        x: Math.round(item.transform[4]),
        y: Math.round(item.transform[5]),
        width: Math.round(item.width),
        height: Math.round(dividedHeight <= 1 ? item.height : dividedHeight),
        text: item.str,
        font: item.fontName,
      });
    });
    pages[page.pageNumber - 1].items = textItems;
    pageParsed(pages);

    const fontIds = new Set(textItems.map((t) => t.font));
    for (const fontId of fontIds) {
      if (!fonts.ids.has(fontId) && fontId.startsWith("g_d")) {
        // Depending on which build of pdfjs-dist is used, the
        // WorkerTransport containing the font objects is either transport or _transport
        const transport = pdfDocument.transport || pdfDocument._transport; // eslint-disable-line no-underscore-dangle
        const font = await new Promise((resolve) =>
          transport.commonObjs.get(fontId, resolve)
        );
        fonts.ids.add(fontId);
        fonts.map.set(fontId, font);
        fontParsed(fonts);
      }
    }
  }
  return {
    fonts,
    metadata,
    pages,
    pdfDocument,
  };
};