> For the complete documentation index, see [llms.txt](https://docs.apryse.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.apryse.com/web/get-started/samples/webviewer-barcode.md).

# Enable Barcode Scanning and Writing with React

Sample project to implement a WebViewer into React for generating barcodes, stamping them onto a PDF and then reading them after they have been flattened

This sample demonstrates a PoC for generating barcodes, stamping them onto a PDF and then reading them after they have been flattened onto the document. Watch a [demo video](https://www.youtube.com/watch?v=KCUL3HoFxkM) or read a [blog](https://apryse.com/blog/annotation/stamp-and-read-barcode-on-pdfs-with-pdftron-sdk) for additional details.

WebViewer provides a slick out-of-the-box responsive UI that enables you to view, annotate and manipulate PDFs and other document types inside any web project.

Click the button below to view the full project in GitHub.

{% tabs %}
{% tab title="JavaScript" %}
{% code title="index.js" lineNumbers="true" %}

```js
import React, { useRef, useEffect, useState } from 'react';
import WebViewer from '@pdftron/webviewer';
import Barcode from '../Barcode';
import javascriptBarcodeReader from 'javascript-barcode-reader';
import jsQR from "jsqr";
import './webviewer.css';

const createSnipTool = ({ docViewer, Tools, Annotations }) => {
  class SnipTool extends Tools.RectangleCreateTool {
    constructor(viewer) {
      super(viewer, 'SnipTool');
      this.defaults.StrokeColor = new Annotations.Color('#ff0000');
      this.defaults.StrokeThickness = 2;
    }
  }

  return new SnipTool(docViewer);
};

const readBarcode = async (copyCanvas) => {
  try {
    const result = await javascriptBarcodeReader({
      image: copyCanvas,
      barcode: 'code-128',
    });
    alert(`Barcode: ${result}`);
  } catch (error) {
    console.log(error);
  }
};

const flattenAllAnnotations = async ({ annotationManager, PDFNet, documentViewer }) => {
  const annots = await annotationManager.exportAnnotations();
  const fdf_doc = await PDFNet.FDFDoc.createFromXFDF(annots);
  const doc = await documentViewer.getDocument().getPDFDoc();
  await doc.fdfUpdate(fdf_doc);
  await doc.flattenAnnotations();
  annotationManager.deleteAnnotations(annotationManager.getAnnotationsList());
  documentViewer.refreshAll();
  documentViewer.updateView();
  documentViewer.getDocument().refreshTextData();
};

const handleSnipAnnotation = async ({ annotation, annotationManager, documentViewer, getCanvasMultiplier }) => {
  const pageIndex = annotation.PageNumber;
  const rootElement = document.getElementsByTagName('apryse-webviewer')[0].shadowRoot;
  const canvasMultiplier = getCanvasMultiplier();
  const pageContainer = rootElement.getElementById('pageContainer' + pageIndex);
  const pageCanvas = pageContainer.querySelector('.canvas' + pageIndex);
  const topOffset = Number.parseFloat(pageContainer.style.top) || 0;
  const leftOffset = Number.parseFloat(pageContainer.style.left) || 0;

  const zoom = documentViewer.getZoomLevel();
  const x = annotation.X * zoom - leftOffset;
  const y = annotation.Y * zoom - topOffset;
  const width = annotation.Width * zoom * canvasMultiplier;
  const height = annotation.Height * zoom * canvasMultiplier;

  const copyCanvas = document.createElement('canvas');
  copyCanvas.width = width;
  copyCanvas.height = height;
  const ctx = copyCanvas.getContext('2d');
  ctx.drawImage(pageCanvas, x, y, width, height, 0, 0, width, height);

  const imageData = ctx.getImageData(0, 0, width, height);
  const code = jsQR(imageData.data, imageData.width, imageData.height);

  if (code) {
    alert(`QR Code: ${code.data}`);
  } else {
    await readBarcode(copyCanvas);
  }

  annotationManager.deleteAnnotation(annotation);
};

const registerToolbar = ({ instance, customSnipTool, onFlatten }) => {
  instance.UI.setToolbarGroup('toolbarGroup-Edit');

  instance.UI.registerTool({
    toolName: 'SnipTool',
    toolObject: customSnipTool,
    buttonImage: '../../../price.svg',
    buttonName: 'snipToolButton',
    tooltip: 'Snipping Tool',
  });

  const editGroup = instance.UI.getGroupedItems('editGroupedItems');
  editGroup.setItems([
    {
      type: 'toolButton',
      toolName: 'SnipTool'
    },
    new instance.UI.Components.CustomButton({
      dataElement: 'customButton',
      className: 'custom-button-class',
      onClick: onFlatten,
      img: '<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M0 0h24v24H0z" fill="none"/><path d="M17 3H5c-1.11 0-2 .9-2 2v14c0 1.1.89 2 2 2h14c1.1 0 2-.9 2-2V7l-4-4zm-5 16c-1.66 0-3-1.34-3-3s1.34-3 3-3 3 1.34 3 3-1.34 3-3 3zm3-10H5V5h10v4z"/></svg>',
      title: 'Flatten Annotations',
    })
  ]);
};

const WebViewerPDFTron = () => {
  const viewer = useRef(null);
  const [viewerInstance, setViewerInstance] = useState(null);

  // if using a class, equivalent of componentDidMount
  useEffect(() => {
    const initializeViewer = async () => {
      const instance = await WebViewer(
        {
          path: '/webviewer/lib',
          initialDoc:
            'https://pdftron.s3.amazonaws.com/downloads/pl/webviewer-demo.pdf',
          fullAPI: true,
          disabledElements: ['ribbons', 'cropToolButton', 'snippingToolButton']
        },
        viewer.current,
      );

      setViewerInstance(instance);
      const {
        documentViewer,
        annotationManager,
        Annotations,
        Tools,
        PDFNet,
        getCanvasMultiplier,
      } = instance.Core;
      await PDFNet.initialize();

      const customSnipTool = createSnipTool({
        docViewer: documentViewer,
        Tools,
        Annotations,
      });

      registerToolbar({
        instance,
        customSnipTool,
        onFlatten: () => flattenAllAnnotations({ annotationManager, PDFNet, documentViewer }),
      });

      customSnipTool.addEventListener('annotationAdded', (annotation) =>
        handleSnipAnnotation({ annotation, annotationManager, documentViewer, getCanvasMultiplier })
      );
    };

    initializeViewer();
  }, []);

  return (
    <div className="container">
      <div className="webviewer" ref={viewer}></div>
      <Barcode instance={viewerInstance} />
    </div>
  );
};

export default WebViewerPDFTron;

```

{% endcode %}
{% endtab %}
{% endtabs %}


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