@aeolun/muhammara/lib/recipe/utils.js

Create, read and modify PDF files and streams. A drop in replacement for hummusjs PDF library

const ANNOTATION_PREFIX = "Annots";

/**
 * Append PDF Page with annotations.
 *
 * @param {any} pdfWriter - Hummus writer.
 * @param {string|any} sourcePDFPath - The path for the output pdfs or Reader stream.
 * @param {number} pageNumber - page number.
 * @param {any} [options={}] - appendPDFPageFromPDF options
 */
function appendPDFPageFromPDFWithAnnotations(
  pdfWriter,
  sourcePDFPath,
  pageNumber
) {
  const cpyCxt = pdfWriter.createPDFCopyingContext(sourcePDFPath);
  const cpyCxtParser = cpyCxt.getSourceDocumentParser();
  const pageDictionary = cpyCxtParser.parsePageDictionary(pageNumber);

  if (!pageDictionary.exists(ANNOTATION_PREFIX)) {
    cpyCxt.appendPDFPageFromPDF(pageNumber);
  } else {
    let reffedObjects;
    pdfWriter.getEvents().once("OnPageWrite", (params) => {
      params.pageDictionaryContext.writeKey(ANNOTATION_PREFIX);
      reffedObjects = cpyCxt.copyDirectObjectWithDeepCopy(
        pageDictionary.queryObject(ANNOTATION_PREFIX)
      );
    });

    cpyCxt.appendPDFPageFromPDF(pageNumber);

    if (reffedObjects && reffedObjects.length > 0) {
      cpyCxt.copyNewObjectsForDirectObject(reffedObjects);
    }
  }
}

/**
 * Append PDF Pages with annotations.
 *
 * @param {any} pdfWriter - Hummus writer.
 * @param {string|any} sourcePDFPath - The path for the output pdfs or Reader stream.
 * @param {any} [options={}] - appendPDFPagesFromPDF options
 */
function appendPDFPagesFromPDFWithAnnotations(
  pdfWriter,
  sourcePDFPath,
  options = {}
) {
  const cpyCxt = pdfWriter.createPDFCopyingContext(sourcePDFPath);
  const cpyCxtParser = cpyCxt.getSourceDocumentParser();

  if (options.specificRanges && options.specificRanges.length) {
    for (const [start, end] of options.specificRanges) {
      for (let i = start; i <= end; ++i) {
        appendPDFPageFromPDFWithAnnotations(pdfWriter, sourcePDFPath, i);
      }
    }
  } else {
    for (let i = 0; i < cpyCxtParser.getPagesCount(); ++i) {
      appendPDFPageFromPDFWithAnnotations(pdfWriter, sourcePDFPath, i);
    }
  }
}

exports.ANNOTATION_PREFIX = ANNOTATION_PREFIX;
exports.appendPDFPageFromPDFWithAnnotations =
  appendPDFPageFromPDFWithAnnotations;
exports.appendPDFPagesFromPDFWithAnnotations =
  appendPDFPagesFromPDFWithAnnotations;