Watermarks/Background possible?

[flecke-anaptis]

Is it possible to use the "embedPage()"-Function to set a Watermark on a Page and Print a second PDF Document onto this Watermark ? I guess Watermark isnt the best explanation what i try to do with it. I have an PDF-File as Layout with some Companie Informations in the Footer and a Logo in the upper right corner (for example) and i want to use this layout as Background for all PDFs which will be created. I already have built a PDF Merger with this libary and now try to implement this Watermark function without using a different libary.

i copied the example on the pdf-Lib Website and the only difference is that i have the layout PDF and the Content PDF as Base64-Strings.

urls is an JsonArray which contains the Base64 PDFs and the second Base64-String is always the Layout/Background-PDF

async function EmbedWatermark(urls) {
  console.log('Watermark will be added');
  console.log(urls)

  // const backgroundURL = 'C:/Users/flecke/Downloads/Briefpapier-kostenlos-015.pdf'

  //Fetch the Background
  const backgroundPdf = await PDFDocument.load(urls[1]);

  //Create a new PDFDocument
  const PDFDoc = await PDFDocument.create();

  //Embed the first page of the Background
  const [background] = await PDFDoc.embedPdf(backgroundPdf);

  //Load the BC Document
  const BCDocument = await PDFDocument.load(urls[0]);

  //Embed the BC Document
  const [BC_PDF] = await PDFDoc.embedPdf(BCDocument)

  //Console Output for debugging
  const docLength = BCDocument.getPageCount();
  console.log("docLength: " + docLength);

  //Get width/height of the Background and scale it
  const backgroundDims = background.scale(0, 9)

  //Get width/height of the BCDocument
  const BC_PDFDims = BC_PDF.scale(1)

  //Add a blank Page to the document
  const page = PDFDoc.addPage();

  //Draw the Background
  page.drawPage(background, {
    ...backgroundDims
  })

  //Draw the BC Document
  page.drawPage(BC_PDF, {
    ...BC_PDFDims
  })

  console.log(pdfDataUri);
  const pdfDataUri = await PDFDoc.saveAsBase64({ dataUri: true })

  var a = document.createElement("a"); //Create <a>
  a.href = pdfDataUri; //Image Base64 Goes here
  a.download = 'WatermarkEmbedded'; //File name Here
  a.click(); //Downloaded files
}