Convert PDF Library bounds to PDF Viewer bounds

28 Feb 20266 minutes to read

Overview

When exporting annotations from the PDF Library, convert the annotation bounds into the PDF Viewer coordinate system so exported annotations appear at the correct position and scale in the viewer.

Steps to convert bounds values

Step 1: Initialize the PdfViewer instance

Create an instance of the PdfViewer and configure it with the required services.

Step 2: Handle export success

Convert the exported blob URL to an object and then extract and convert the annotation bounds.

Step 3: Convert Blob URL to object

Fetch the blob data and convert it into a JSON object.

Server-Backed

<template>
  <div id="app">
    <ejs-pdfviewer
      id="pdfViewer"
      ref="pdfviewer"
      :documentPath="documentPath"
      :serviceUrl="serviceUrl"
      style="height: 640px;"
      @exportSuccess="handleExportSuccess"
    >
    </ejs-pdfviewer>
  </div>
</template>

<script>
import { PdfViewerComponent, Toolbar, Magnification, Navigation,
         Annotation, TextSelection, TextSearch, FormFields, FormDesigner, PageOrganizer } from '@syncfusion/ej2-vue-pdfviewer';
export default {
  name: 'App',
  components: {
    'ejs-pdfviewer': PdfViewerComponent
  },
  data() {
    return {
      documentPath: "https://cdn.syncfusion.com/content/pdf/pdf-succinctly.pdf",
      serviceUrl: "https://document.syncfusion.com/web-services/pdf-viewer/api/pdfviewer",
    };
  },
  provide: {
    PdfViewer: [Toolbar, Magnification, Navigation, Annotation, TextSelection, TextSearch, FormFields, FormDesigner, PageOrganizer]
  },
  methods: {
    handleExportSuccess(args) {
      const blobURL = args.exportData;
      // Converting the exported blob into an object
      this.convertBlobURLToObject(blobURL)
        .then((objectData) => {
          console.log(objectData);
          const shapeAnnotationData = objectData.pdfAnnotation[0].shapeAnnotation;
          shapeAnnotationData.forEach(data => {
            if (data && data.rect && parseInt(data.rect.width)) {
              const pageHeight = this.$refs.pdfviewer.getPageInfo(parseInt(data.page)).height;
              // Converting PDF Library values into PDF Viewer values.
              const rect = {
                x: (parseInt(data.rect.x) * 96) / 72,
                y: (parseInt(pageHeight) - parseInt(data.rect.height)) * 96 / 72,
                width: (parseInt(data.rect.width) - parseInt(data.rect.x)) * 96 / 72,
                height: (parseInt(data.rect.height) - parseInt(data.rect.y)) * 96 / 72,
              };
              console.log(data.name);
              console.log(rect);
              console.log("-------------------------");
            }
          });
        })
        .catch((error) => {
          console.error('Error converting Blob URL to object:', error);
        });
    },
    //Function to convert Blob URL to object
    convertBlobURLToObject(blobURL) {
      return fetch(blobURL)
        .then((response) => response.blob())
        .then((blobData) => {
          return new Promise((resolve, reject) => {
            const reader = new FileReader();
            reader.onloadend = () => {
              resolve(JSON.parse(reader.result));
            };
            reader.onerror = reject;
            reader.readAsText(blobData);
          });
        });
    }
  }
}
</script>

Conclusion

These steps convert PDF Library bounds values into PDF Viewer bounds values when exporting annotations as JSON, helping maintain accurate annotation placement.

View sample in GitHub