Flatten PDF annotations using JavaScript

Annotation or form flattening refers to the operation that changes annotations (such as markup, widgets, 3D models, etc.) into a static area that is part of the PDF document, just like the other text and images in the document. By flattening and merging existing annotation appearances with page content, the original annotations are deleted from the PDF pages. Try out the flatten annotations sample in WebViewer Showcase.

Forms share a relationship with annotations because the visual display of a form is a widget annotation. The process of flattening annotations therefore can optionally flatten forms as well.

Note that it is not possible to undo the flatten operation. If you are interested in modifying annotations so they cannot be edited or deleted then you should consider setting to ReadOnly instead of flattening them. See the ReadOnly property on the Annotation class for more details.

Flattening annotations can be performed when getting the PDF file data or while downloading the PDF file locally. There is also the option to flatten select annotations .

Use the getFileData method and the flatten option for the annotations to be flattened in the document output when getting the data for uploading to a server.

WebViewer({
  fullAPI: true,
  // other constructor options
}, viewerElement).then(instance => {
  const { documentViewer, annotationManager } = instance.Core;

  document.getElementById('myBtn').addEventListener('click', async () => {
    const doc = documentViewer.getDocument();
    const xfdfString = await annotationManager.exportAnnotations();
    const options = { xfdfString, flatten: true };
    const data = await doc.getFileData(options);
    const arr = new Uint8Array(data);
    const blob = new Blob([arr], { type: 'application/pdf' });
    // upload blob to your server
  });
});

Use the downloadPdf method and the flatten option for the annotations to be flattened in the document output when downloading the PDF locally.

WebViewer({
  fullAPI: true,
  // other constructor options
}, viewerElement).then(instance => {

  document.getElementById('myBtn').addEventListener('click', () => {
    // download pdf with all annotations flattened
    instance.UI.downloadPdf({
      includeAnnotations: true,
      flatten: true,
    });
  });
});

Use flattenAnnotations method to flatten all annotations into a document.

WebViewer({
  fullAPI: true,
  // other constructor options
}, viewerElement).then(instance => {
  const { documentViewer, PDFNet, annotationManager } = instance.Core;

  document.getElementById('myBtn').addEventListener('click', async () => {
    await PDFNet.initialize();
    const doc = await documentViewer.getDocument().getPDFDoc();

    // export annotations from the document
    const annots = await annotationManager.exportAnnotations();

    // Run PDFNet methods with memory management
    await PDFNet.runWithCleanup(async () => {

      // lock the document before a write operation
      // runWithCleanup will auto unlock when complete
      doc.lock(); 

      // import annotations to PDFNet
      const fdf_doc = await PDFNet.FDFDoc.createFromXFDF(annots);
      await doc.fdfUpdate(fdf_doc);

      // flatten all annotations in the document
      await doc.flattenAnnotations();

      // or optionally only flatten forms
      // await doc.flattenAnnotations(true);

      // clear the original annotations
      annotationManager.deleteAnnotations(annotationManager.getAnnotationsList());

      // optionally only clear widget annotations if forms were only flattened
      // const widgetAnnots = annots.filter(a => a instanceof Annotations.WidgetAnnotation);
      // annotationManager.deleteAnnotations(widgetAnnots);
    });

    // clear the cache (rendered) data with the newly updated document
    documentViewer.refreshAll();

    // Update viewer to render with the new document
    documentViewer.updateView();

    // Refresh searchable and selectable text data with the new document
    documentViewer.getDocument().refreshTextData();
  });
});

Use the flatten method on annotation objects to flatten select annotations into the document.

WebViewer({
  fullAPI: true,
  // other constructor options
}, viewerElement).then(instance => {
  const { documentViewer, PDFNet, annotManager } = instance.Core;

  document.getElementById('myBtn').addEventListener('click', async () => {
    await PDFNet.initialize();
    const doc = await documentViewer.getDocument().getPDFDoc();

    // export annotations from the document
    const annots = await annotManager.exportAnnotations();

    // Run PDFNet methods with memory management
    await PDFNet.runWithCleanup(async () => {

      // lock the document before a write operation
      // runWithCleanup will auto unlock when complete
      doc.lock();

      // import annotations to PDFNet
      const fdf_doc = await PDFNet.FDFDoc.createFromXFDF(annots);
      await doc.fdfUpdate(fdf_doc);

      const page = await doc.getPage(1);
      const annotation = await page.getAnnot(0);
      await annotation.flatten(page); //flatten this annotation

      // clear the original annotations
      annotManager.deleteAnnotations(annotManager.getAnnotationsList());

      // import annotations from PDFNet
      const fdfDoc = await doc.fdfExtract(PDFNet.PDFDoc.ExtractFlag.e_both);
      const xfdf = await fdfDoc.saveAsXFDFAsString();
      annotManager.importAnnotations(xfdf);
    });

    // clear the cache (rendered) data with the newly updated document
    documentViewer.refreshAll();

    // Update viewer to render with the new document
    documentViewer.updateView();

    // Refresh searchable and selectable text data with the new document
    documentViewer.getDocument().refreshTextData();
  });
});