Adding a stamp to PDFs using Javascript

1const { documentViewer } = instance.Core;
2const path = '/samples/full-apis/TestFiles/butterfly.png'
3
4// Promise resolves with options object
5const promise = new Promise(resolve => {
6  const img = new Image();
7  const options = {
8    custom: async (ctx, pageIndex, pageWidth, pageHeight) => {
9
10      ctx.font = '50px serif';
11      ctx.fillText('Hello world', 50, 90);
12
13      ctx.drawImage(
14        img,
15        pageWidth / 2 - img.width / 2,
16        pageHeight / 2 - img.height / 2
17      );
18
19      // the pageIndex is also passed in so you could have
20      // a different watermark for each page
21    }
22  };
23  img.onload = () => { 
24    return resolve(options);
25  };
26  img.src = path;
27});
28
29documentViewer.setWatermark(promise);

1let imageName = 'path to your image file';
2let fileName = 'path to your PDF file';
3
4const { documentViewer, PDFNet } = instance.Core;
5
6document.getElementById('myBtn').addEventListener('click', async () => {
7  await PDFNet.initialize();
8  const doc = await documentViewer.getDocument().getPDFDoc();
9
10  // Run PDFNet methods with memory management
11  await PDFNet.runWithCleanup(async () => {
12
13    // lock the document before a write operation
14    // runWithCleanup will auto unlock when complete
15    doc.lock();
16    const s = await PDFNet.Stamper.create(PDFNet.Stamper.SizeType.e_relative_scale, 0.5, 0.5);
17
18    // Specifies if the stamp is to be stamped as an annotation.
19    // note that stamps created with this setting do not work with SetAsBackground, HasStamps, and DeleteStamps, if annotation is true.
20    //s.setAsAnnotation(true); 
21
22    await s.setAlignment(PDFNet.Stamper.HorizontalAlignment.e_horizontal_center, PDFNet.Stamper.VerticalAlignment.e_vertical_top);
23    const font = await PDFNet.Font.create(doc, PDFNet.Font.StandardType1Font.e_courier);
24    await s.setFont(font);
25    const redColorPt = await PDFNet.ColorPt.init(1, 0, 0, 0);
26    await s.setFontColor(redColorPt);
27    await s.setTextAlignment(PDFNet.Stamper.TextAlignment.e_align_right);
28    await s.setAsBackground(false);
29    const pgSet = await PDFNet.PageSet.createRange(1, 2);
30    await s.stampText(doc, 'This is a title!', pgSet);
31
32    const img = await PDFNet.Image.createFromURL(doc, imageName);
33    s.setAsBackground(false);
34    const pgSetImage = await PDFNet.PageSet.createRange(1, 1);
35    await s.setAlignment(PDFNet.Stamper.HorizontalAlignment.e_horizontal_right, PDFNet.Stamper.VerticalAlignment.e_vertical_bottom);
36    await s.stampImage(doc, img, pgSetImage);
37
38    const srcDoc = await PDFNet.PDFDoc.createFromURL(fileName);
39    const srcPage = await srcDoc.getPage(1);
40    await s.setAlignment(PDFNet.Stamper.HorizontalAlignment.e_horizontal_left, PDFNet.Stamper.VerticalAlignment.e_vertical_bottom);
41    await s.stampPage(doc, srcPage, pgSet);
42  });
43
44  // clear the cache (rendered) data with the newly updated document
45  documentViewer.refreshAll();
46
47  // Update viewer to render with the new document
48  documentViewer.updateView();
49
50  // Refresh searchable and selectable text data with the new document
51  documentViewer.getDocument().refreshTextData();
52});