Section:

OCR Showcase Demo Code Sample

Requirements
View Demo
Server SDK
Web SDK
Package: OCR
Module: OCR

Generate searchable PDFs from scanned documents or images using OCR (Optical Character Recognition). The scanned file that contains characters is converted into machine-readable searchable and selectable text as a PDF document.

This sample code includes Server SDK processing in JavaScript, with UI provided by WebViewer. If a viewer is not needed, or you want to work with a different language or framework for the Server SDK, please check out our Server SDK OCR Sample Code.

This demo allows you to:

  • Choose your own PDF or image file
  • Select default documents in various languages: English, French, Spanish, Italian, German, Russian
  • Convert into characters that are selectable and searchable
  • Extract the characters as string

Implementation steps

To add OCR Module capability with Server SDK, and view with WebViewer:

Step 1: Follow get-started in JavaScript for Server SDK
Step 2: Follow get-started in your preferred web stack for WebViewer
Step 3: Download OCR Module
Step 4: Add the ES6 JavaScript sample code provided in this guide

Note: Only the first page is processed in this demo.
1// ES6 Compliant Syntax
2// GitHub Copilot v1.0 - GPT-4 Model - September 24, 2024
3// File: ocr-module/client/index.js
4
5import WebViewer from '@pdftron/webviewer';
6
7function initializeWebViewer() {
8
9  console.log('Initializing WebViewer...');
10  const viewerElement = document.getElementById('viewer');
11  if (!viewerElement) {
12    console.error('❌ Viewer element not found. Please ensure there is a div with id "viewer" in your HTML.');
13    return;
14  }
15
16  WebViewer({
17    path: '/lib',
18    initialDoc: UIElements.demoFilesPath + UIElements.ocrdemofiles['eng'],
19    enableFilePicker: true, // Enable file picker to open files. In WebViewer -> menu icon -> Open File.
20    enableMeasurement: false,
21    loadAsPDF: true,
22    licenseKey: 'YOUR_LICENSE_KEY',
23  }, viewerElement).then(instance => {
24
25    // Once the PDF document is loaded, send it to the server.
26    // The sent PDF document will be processed by the server,
27    // by extracting form fields JSON data when the user clicks the Detect Form Fields button.
28    instance.Core.documentViewer.addEventListener('documentLoaded', async () => {
29      if (!UIElements.loadingFromList) {
30        UIElements.loadedFromPicker = true;
31        UIElements.loadLabelText = ' Use file picker to load your own file';
32      }
33      
34      // If next time we load from list, this will be set to true again.
35      UIElements.loadingFromList = false; 
36      
37      // Customize the main webviewer left panel after loading completes.
38      UIElements.customizeUI(instance, performOCR);
39    });
40    console.log('✅ WebViewer loaded successfully.');
41  }).catch((error) => {
42    console.error('Failed to initialize WebViewer:', error);
43  });
44}
45
46// Perform OCR by sending the current PDF page to the server.
47const performOCR = async (instance) => {
48  // Reset JSON data
49  UIElements.jsonData = null;
50  let resultText = '';
51
52  // Preparation of the PDF blob to be sent to the server.
53  const doc = instance.Core.documentViewer.getDocument();
54  const currentPage = instance.Core.documentViewer.getCurrentPage();
55  const xfdfString = await instance.Core.annotationManager.exportAnnotations(); // obtaining annotations in the loaded document
56  const data = await doc.getFileData({ xfdfString });
57  const arr = new Uint8Array(data);
58  const blob = new Blob([arr], { type: 'application/pdf' });
59  const formData = new FormData();
60  formData.append(doc.filename, blob, doc.filename);
61  // Send the PDF blob to the server for processing.
62  new Promise(function (resolve, reject) {
63    console.log('🚀 Sending PDF to server for processing...');
64    fetch(`http://localhost:5050/server/handler.js?filename=${doc.filename}&currentPage=${currentPage}&lang=${UIElements.selectedLanguage}`, {
65      method: 'POST',
66      body: formData,
67    }).then(function (response) {
68
69      if (response.status === 200) {
70        response.text().then(function (json) {
71          UIElements.jsonData = json;
72          const ocrResult = JSON.parse(UIElements.jsonData);
73
74          for (const page of ocrResult.Page) {
75            for (const para of page.Para) {
76              for (const line of para.Line) {
77                for (const word of line.Word) {
78                  resultText += word.text + ' ';
79                }
80                resultText += '\n';
81              }
82            }
83          }
84          resolve();
85        })
86      } else {
87        const errorText = `❌ Server responded with status: ${response.status}`;
88        resultText = errorText + resultText;
89        console.error(resultText);
90        reject(new Error(`Server error: ${response.status}`));
91      }
92    }).catch(function (error) {
93      let errorText = '❌ Failed to connect to server: ' + error;
94      errorText += '\n📍 Attempted URL: http://localhost:5050/server/handler.js';
95      errorText += '\n🔍 This likely means the OCR server is not running on port 5050';
96      console.error(errorText);
97      resultText = errorText + resultText;
98      reject(error);
99    });
100  }).catch(function (error) {
101    const errorText = '❌ Error in PDF upload promise: ' + error;
102    console.error(errorText);
103    resultText = errorText + resultText;
104  }).finally(function () {
105    UIElements.ocrText.textContent = resultText;
106    UIElements.setLoading(instance, false);
107  });
108}
109
110
111function loadUIElementsScript() {
112  return new Promise((resolve, reject) => {
113    if (window.UIElements) {
114      console.log('UIElements already loaded');
115      resolve();
116      return;
117    }
118    
119    const script = document.createElement('script');
120    script.src = '/showcase-demos/ocr-module/client/ui-elements.js';
121    script.onload = function () {
122      console.log('✅ UIElements script loaded successfully');
123      resolve();
124    };
125    script.onerror = function () {
126      console.error('Failed to load UIElements script');
127      reject(new Error('Failed to load ui-elements.js'));
128    };
129    document.head.appendChild(script);
130  });
131}
132
133// Load UIElements script first, then initialize WebViewer.
134loadUIElementsScript().then(() => {
135  initializeWebViewer();
136}).catch((error) => {
137  console.error('Failed to load UIElements:', error);
138});

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