Control annotation visibility in PDF Viewer for Vue

Overview

This guide explains how to control the visibility of PDF annotations in documents loaded and saved using the Syncfusion PDF Viewer in Vue, so annotations are visible only in the viewer when required.

How to Control Annotation Visibility

Steps to control annotation visibility

Step 1: Follow the steps provided in the Vue PDF Viewer Getting Started documentation to create a simple PDF Viewer sample.

Step 2: Set Up Your Vue Component

Create an Vue component and update the template to include a button that triggers the download operation. 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>

Following these steps ensures annotations are visible in the Syncfusion PDF Viewer while controlling their visibility in the downloaded PDF.

View sample in GitHub