Control annotation visibility in PDF Viewer for Vue

28 Feb 20268 minutes to read

Overview

This guide shows how to display annotations in the Vue PDF Viewer while preventing them from appearing in the saved/downloaded PDF.

How to Control Annotation Visibility

Steps to control annotation visibility

Step 1: Follow the steps in the getting-started guide (https://help.syncfusion.com/document-processing/pdf/pdf-viewer/vue/getting-started) to create a basic PDF Viewer sample.

Step 2: Add controls for annotation modification and downloading

Add buttons in the component template to modify annotations and to trigger a download of the PDF. Additionally, create a function to save the document with the PDF annotation flag set to noView.

Standalone

<template>
  <div id="app">
    <button v-on:click="save">Download</button>
      <ejs-pdfviewer
        id="pdfViewer"
        ref="pdfviewer"
        :documentPath="documentPath"
        :documentLoad="documentLoad"
        :resourceUrl="resourceUrl">
      </ejs-pdfviewer>
  </div>
</template>

<script>

import { PdfViewerComponent, Toolbar, Magnification, Navigation,
         LinkAnnotation, BookmarkView, Annotation, ThumbnailView,
         Print, TextSelection, TextSearch, FormFields, FormDesigner, PageOrganizer, DisplayMode} from '@syncfusion/ej2-vue-pdfviewer';

// Import PdfAnnotationFlag and PdfDocument from the Syncfusion PDF library.
import {PdfDocument, PdfAnnotationFlag} from '@syncfusion/ej2-pdf';

export default {
  name: 'App',
  components: {
    "ejs-pdfviewer": PdfViewerComponent
  },
  data () {
    return {
      resourceUrl:"https://cdn.syncfusion.com/ej2/31.2.2/dist/ej2-pdfviewer-lib",
      documentPath:"https://cdn.syncfusion.com/content/pdf/annotations-v1.pdf",
    };
  },
  provide: {
    PdfViewer: [ Toolbar, Magnification, Navigation, LinkAnnotation, BookmarkView, Annotation,
                 ThumbnailView, Print, TextSelection, TextSearch, FormFields, FormDesigner, PageOrganizer]},
  methods: {
    documentLoad: function () {
     let viewer = this.$refs.pdfviewer.ej2Instances;
      //Code snippet to add basic annotations. You can also include other annotations as needed.
                viewer.annotation.addAnnotation("Highlight", {
                    bounds: [{ x: 97, y: 610, width: 350, height: 14 }],
                    pageNumber: 1
                });
                viewer.annotation.addAnnotation("Underline", {
                    bounds: [{ x: 97, y: 723, width: 353.5, height: 14 }],
                    pageNumber: 1
                });
                viewer.annotation.addAnnotation("Strikethrough", {
                    bounds: [{ x: 97, y: 836, width: 376.5, height: 14 }],
                    pageNumber: 1
                });
  },
  save: function(){
      // Get the PDF viewer instance
      let viewer = this.$refs.pdfviewer.ej2Instances;

      // Save the current PDF document as a Blob
      viewer.saveAsBlob().then((blob) => {
        const reader = new FileReader();
        reader.onload = function () {
          let base64data = reader.result;
          // Extract base64 string from Data URL
          const base64EncodedData = base64data.split('base64,')[1];
          // Create a PdfDocument instance with base64 data
          const document1 = new PdfDocument(base64EncodedData);
          // Modify flag for each annotation
          for (let i = 0; i < document1.pageCount; i++) {
            const page = document1.getPage(i);
            for (let j = 0; j < page.annotations.count; j++) {
              const annot = page.annotations.at(j);
              // Set flag to noView
              annot.flags |= PdfAnnotationFlag.noView;
            }
          }
          // Save modified document as a blob
          document1.saveAsBlob().then((modifiedBlob) => {
            const internalReader = new FileReader();
            internalReader.onload = function () {
              const modifiedBase64 = internalReader.result;
              // Create a link to download the modified PDF
              const downloadLink = document.createElement('a');
              downloadLink.href = modifiedBase64;
              downloadLink.download = 'modified.pdf';
              downloadLink.click();
            };
            internalReader.readAsDataURL(modifiedBlob.blobData);
          });
        };
        reader.readAsDataURL(blob);
      });
    }

  }
}
</script>

After performing these steps, annotations remain visible in the viewer but are hidden in the downloaded PDF.

View sample in GitHub