It is necessary to make a simple web form where will be downloaded pdf file, different they can be with pictures with etc. I want it to change (in place of one word was another) these words can be scattered in different parts of the pdf file, and this pdf without changes could be downloaded back after editing.Already tried through different libraries and I can write text but delete the old and in its place a new text, the functionality of libraries does not allow, now I’m trying through hummus here is the code of html page
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>PDF Upload</title>
</head>
<body>
<h1>PDF Upload</h1>
<form id="uploadForm" enctype="multipart/form-data">
<input type="file" name="pdfFile" accept=".pdf" required>
<button type="submit">Upload PDF</button>
</form>
<script>
document.getElementById('uploadForm').addEventListener('submit', async (event) => {
event.preventDefault();
const formData = new FormData(event.target);
try {
const response = await fetch('/upload-pdf', {
method: 'POST',
body: formData
});
if (!response.ok) {
throw new Error('Error uploading file: ' + response.statusText);
}
const result = await response.json();
alert(result.message);
} catch (error) {
console.error('Error:', error);
alert('Error uploading file: ' + error.message);
}
});
</script>
</body>
</html>
and the server code
const app = express();
const port = 3000;
const path = require('path'); // Importing the path module
const hummus = require('hummus'); // Importing HummusJS
// Route for displaying the HTML page
app.get('/', (req, res) => {
res.sendFile(path.join(__dirname, 'public', 'index.html')); // Sending the HTML file on GET request to the root route
});
/*---------------------------------------------------------------------------------------------------------------------------------------------------------------*/
// Working with PDF
const fs = require('fs');
const { PDFDocument, rgb } = require('pdf-lib'); // Importing the pdf-lib library
const pdfParse = require('pdf-parse');
const multer = require('multer');
// PDF Upload
// Setting up Multer for file uploads
const storage = multer.diskStorage({
destination: function (req, file, cb) {
cb(null, 'uploads/'); // Ensure this folder exists
},
filename: function (req, file, cb) {
cb(null, file.originalname); // Save the file with its original name
}
});
const upload = multer({ storage: storage });
async function modifyExistingPDF(sourceFilePath, findText, replaceText) {
// Check if the source file exists
if (!fs.existsSync(sourceFilePath)) {
throw new Error(`Source file ${sourceFilePath} does not exist.`);
}
// Create a writer for modifying the PDF
const modPdfWriter = hummus.createWriterToModify(sourceFilePath, { modifiedFilePath: './output.pdf', compress: false });
// Get the copying context
const sourceParser = modPdfWriter.createPDFCopyingContextForModifiedFile().getSourceDocumentParser();
// Read the first page
const pageObject = sourceParser.parsePage(0);
// Get the contents stream
const contentsStream = sourceParser.queryDictionaryObject(pageObject.getDictionary(), 'Contents');
// Check for the existence of the contents stream
if (!contentsStream) {
throw new Error('Contents stream not found');
}
// Read the original block of text data
const data = [];
const readStream = sourceParser.startReadingFromStream(contentsStream);
while (readStream.notEnded()) {
const readData = readStream.read(10000);
data.push(...readData);
}
// Create a new string
let string = Buffer.from(data).toString('utf-8');
// Log the original string
console.log('Original String:', string);
// Replace the text
if (string.includes(findText)) {
string = string.replace(new RegExp(findText, 'g'), replaceText);
} else {
throw new Error(`Text "${findText}" not found in PDF.`);
}
// Create and write the new text object
const objectsContext = modPdfWriter.getObjectsContext();
const textObjectID = pageObject.getDictionary().toJSObject().Contents.getObjectID();
// Check if this is indeed the object we want to modify
if (typeof textObjectID !== 'number') {
throw new Error('Invalid text object ID.');
}
objectsContext.startModifiedIndirectObject(textObjectID);
// Create a stream and write the data
const stream = objectsContext.startUnfilteredPDFStream();
stream.getWriteStream().write(Buffer.from(string, 'utf-8'));
objectsContext.endPDFStream(stream);
objectsContext.endIndirectObject();
// Finish writing the PDF
modPdfWriter.end();
// Remove old objects that are no longer in use
hummus.recrypt('./output.pdf', './outputClean.pdf');
}
app.post('/upload-pdf', upload.single('pdfFile'), async (req, res) => {
console.log('File is being uploaded to the server...');
if (!req.file) {
return res.status(400).json({ error: 'File not uploaded' });
}
const sourceFilePath = req.file.path; // Path to the uploaded file
const findText="Word"; // Text to search for (you can change this)
const replaceText="Letter"; // Text to replace with
try {
await modifyExistingPDF(sourceFilePath, findText, replaceText); // Processing the PDF
res.json({ message: 'PDF processed successfully!' });
} catch (error) {
console.error('Error processing PDF:', error);
res.status(500).json({ error: 'Error processing PDF' });
}
});
/*---------------------------------------------------------------------------------------------------------------------------------------------------------------*/
// Starting the server
app.listen(port, () => {
console.log(`Server is running at http://localhost:${port}`);
});
………………………….
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