File size: 4,390 Bytes
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* PDF processing utilities using PDF.js
* Handles PDF text extraction and image conversion in the browser
*/
import { browser } from '$app/environment';
import { MimeTypeApplication, MimeTypeImage } from '$lib/enums';
import * as pdfjs from 'pdfjs-dist';
type TextContent = {
items: Array<{ str: string }>;
};
if (browser) {
// Import worker as text and create blob URL for inline bundling
import('pdfjs-dist/build/pdf.worker.min.mjs?raw')
.then((workerModule) => {
const workerBlob = new Blob([workerModule.default], { type: 'application/javascript' });
pdfjs.GlobalWorkerOptions.workerSrc = URL.createObjectURL(workerBlob);
})
.catch(() => {
console.warn('Failed to load PDF.js worker, PDF processing may not work');
});
}
/**
* Convert a File object to ArrayBuffer for PDF.js processing
* @param file - The PDF file to convert
* @returns Promise resolving to the file's ArrayBuffer
*/
async function getFileAsBuffer(file: File): Promise<ArrayBuffer> {
return new Promise((resolve, reject) => {
const reader = new FileReader();
reader.onload = (event) => {
if (event.target?.result) {
resolve(event.target.result as ArrayBuffer);
} else {
reject(new Error('Failed to read file.'));
}
};
reader.onerror = () => {
reject(new Error('Failed to read file.'));
};
reader.readAsArrayBuffer(file);
});
}
/**
* Extract text content from a PDF file
* @param file - The PDF file to process
* @returns Promise resolving to the extracted text content
*/
export async function convertPDFToText(file: File): Promise<string> {
if (!browser) {
throw new Error('PDF processing is only available in the browser');
}
try {
const buffer = await getFileAsBuffer(file);
const pdf = await pdfjs.getDocument({ data: buffer }).promise;
const numPages = pdf.numPages;
const textContentPromises: Promise<TextContent>[] = [];
for (let i = 1; i <= numPages; i++) {
// eslint-disable-next-line @typescript-eslint/no-explicit-any
textContentPromises.push(pdf.getPage(i).then((page: any) => page.getTextContent()));
}
const textContents = await Promise.all(textContentPromises);
const textItems = textContents.flatMap((textContent: TextContent) =>
textContent.items.map((item) => item.str ?? '')
);
return textItems.join('\n');
} catch (error) {
console.error('Error converting PDF to text:', error);
throw new Error(
`Failed to convert PDF to text: ${error instanceof Error ? error.message : 'Unknown error'}`
);
}
}
/**
* Convert PDF pages to PNG images as data URLs
* @param file - The PDF file to convert
* @param scale - Rendering scale factor (default: 1.5)
* @returns Promise resolving to array of PNG data URLs
*/
export async function convertPDFToImage(file: File, scale: number = 1.5): Promise<string[]> {
if (!browser) {
throw new Error('PDF processing is only available in the browser');
}
try {
const buffer = await getFileAsBuffer(file);
const doc = await pdfjs.getDocument({ data: buffer }).promise;
const pages: Promise<string>[] = [];
for (let i = 1; i <= doc.numPages; i++) {
const page = await doc.getPage(i);
const viewport = page.getViewport({ scale });
const canvas = document.createElement('canvas');
const ctx = canvas.getContext('2d');
canvas.width = viewport.width;
canvas.height = viewport.height;
if (!ctx) {
throw new Error('Failed to get 2D context from canvas');
}
const task = page.render({
canvasContext: ctx,
viewport: viewport,
canvas: canvas
});
pages.push(
task.promise.then(() => {
return canvas.toDataURL(MimeTypeImage.PNG);
})
);
}
return await Promise.all(pages);
} catch (error) {
console.error('Error converting PDF to images:', error);
throw new Error(
`Failed to convert PDF to images: ${error instanceof Error ? error.message : 'Unknown error'}`
);
}
}
/**
* Check if a file is a PDF based on its MIME type
* @param file - The file to check
* @returns True if the file is a PDF
*/
export function isPdfFile(file: File): boolean {
return file.type === MimeTypeApplication.PDF;
}
/**
* Check if a MIME type represents a PDF
* @param mimeType - The MIME type to check
* @returns True if the MIME type is application/pdf
*/
export function isApplicationMimeType(mimeType: string): boolean {
return mimeType === MimeTypeApplication.PDF;
}
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