Under the hood, pdf_barcode_decoder renders PDF pages natively using Android PdfRenderer and Apple iOS PDFKit, then extracts barcodes using native, high-performance engines (ZXing Core on Android and Apple Vision Framework on iOS).

🚀 Key Features #

• ⚡ Zero External Cloud/Network Dependencies — 100% offline, private, and on-device.
• 🪶 Lightweight & Clean — Zero Google Play Services, ML Kit, or Firebase dependencies.
• 📄 Multiple Input Sources — Decode directly from File, in-memory Uint8List, or bundled asset paths.
• 🎯 Multi-Barcode Detection — Detects multiple barcodes on the same page with IoU-based deduplication.
• 📐 Precise Bounding Boxes — Returns exact pixel coordinates (Rect) for bounding overlays and region cropping.
• ⚙️ Configurable Pipeline — Control rendering resolution (DPI), page ranges (maxPages, firstPageOnly), early stopping (stopAfterFirst), and barcode format filters.
• 🔒 Android 15 (16KB Page Size) Ready — Pure Java/Kotlin implementation without problematic C/C++ native binaries.

📱 Platform Support #

📦 Supported Barcode Formats #

🏗️ Architecture & How It Works #

┌─────────────────────────────────────────────────────────────┐
│                    Flutter Application                      │
│   PdfBarcodeDecoder.decode() / decodeFile() / decodeAsset()  │
└──────────────────────────────┬──────────────────────────────┘
                               │
                      Method Channel (decodePdf)
                               │
            ┌──────────────────┴──────────────────┐
            ▼                                     ▼
┌───────────────────────┐             ┌───────────────────────┐
│     Android Host      │             │       iOS Host        │
│  (PdfDecodeManager)   │             │  (PdfDecodeManager)   │
├───────────────────────┤             ├───────────────────────┤
│ 1. PdfRenderer        │             │ 1. PDFKit             │
│    (Render at DPI)    │             │    (Render at DPI)    │
│ 2. ZXing Core         │             │ 2. Vision Framework   │
│    (MultiFormatReader)│             │    (DetectBarcodes)   │
│ 3. IoU Deduplication  │             │ 3. Coordinate Scaling │
└───────────┬───────────┘             └───────────┬───────────┘
            │                                     │
            └──────────────────┬──────────────────┘
                               ▼
              List<PdfBarcode> (with Page & Rect)

📥 Getting Started #

Add pdf_barcode_decoder to your pubspec.yaml dependencies:

dependencies:
  pdf_barcode_decoder: ^0.0.1

Or run:

flutter pub add pdf_barcode_decoder

💡 Usage Examples #

1. Decode from a File (e.g. from file_picker or camera capture) #

import 'dart:io';
import 'package:pdf_barcode_decoder/pdf_barcode_decoder.dart';

Future<void> scanPdfFile(String filePath) async {
  final file = File(filePath);

  final List<PdfBarcode> barcodes = await PdfBarcodeDecoder.decodeFile(file);

  for (final barcode in barcodes) {
    print('Found ${barcode.type.name} on Page ${barcode.page + 1}: ${barcode.value}');
    print('Bounding box: ${barcode.boundingBox}');
  }
}

2. Decode from In-Memory Bytes (e.g. downloaded over HTTP) #

import 'dart:typed_data';
import 'package:http/http.dart' as http;
import 'package:pdf_barcode_decoder/pdf_barcode_decoder.dart';

Future<void> scanPdfFromUrl(String url) async {
  final response = await http.get(Uri.parse(url));
  final Uint8List pdfBytes = response.bodyBytes;

  final List<PdfBarcode> barcodes = await PdfBarcodeDecoder.decode(pdfBytes);
  print('Found ${barcodes.length} barcode(s) in downloaded PDF.');
}

3. Decode from Bundled App Asset #

import 'package:pdf_barcode_decoder/pdf_barcode_decoder.dart';

Future<void> scanBundledPdf() async {
  final List<PdfBarcode> barcodes = await PdfBarcodeDecoder.decodeAsset(
    'assets/invoices/sample_invoice.pdf',
  );

  for (final b in barcodes) {
    print('Barcode value: ${b.value}');
  }
}

4. Advanced Configuration #

Fine-tune rendering quality, filter specific formats, scan only specific pages, or exit early:

import 'dart:io';
import 'package:pdf_barcode_decoder/pdf_barcode_decoder.dart';

final barcodes = await PdfBarcodeDecoder.decodeFile(
  File('/path/to/shipping_label.pdf'),
  config: const DecoderConfig(
    // Rendering resolution (higher DPI = better recognition of small/dense barcodes)
    dpi: 300,

    // Scan only the first page
    firstPageOnly: false,

    // Exit immediately after finding the first barcode
    stopAfterFirst: true,

    // Scan up to the first 3 pages
    maxPages: 3,

    // Target specific barcode formats
    formats: [
      BarcodeFormat.qr,
      BarcodeFormat.pdf417,
      BarcodeFormat.code128,
    ],
  ),
);

5. Error Handling #

All platform and rendering errors are wrapped in a typed PdfBarcodeException:

import 'dart:io';
import 'package:pdf_barcode_decoder/pdf_barcode_decoder.dart';

try {
  final barcodes = await PdfBarcodeDecoder.decodeFile(File('protected.pdf'));
} on PdfBarcodeException catch (e) {
  switch (e.code) {
    case 'ENCRYPTED_PDF':
      print('Password-protected PDFs cannot be scanned.');
      break;
    case 'INVALID_PDF':
      print('The provided file is corrupted or not a valid PDF.');
      break;
    case 'RENDER_FAILED':
      print('Failed to render PDF pages: ${e.message}');
      break;
    default:
      print('Decoding error [${e.code}]: ${e.message}');
  }
}

📖 API Reference #

DecoderConfig #

PdfBarcode #

⚡ Performance & Best Practices #

1. Choosing the Optimal DPI:
   • 150 DPI — Fast; suitable for large standard QR codes and shipping label barcodes.
   • 300 DPI (Default) — Recommended balance for crisp renders, PDF417 boarding passes, and multi-code documents.
   • 400+ DPI — Use when barcodes are physically tiny or high-density DataMatrix codes.
2. Page Limits: For long documents (e.g., 50+ page invoices), always supply maxPages or stopAfterFirst: true if you only need the header barcode.
3. Memory Management: Both native Android and iOS engines recycle page bitmaps and autorelease pools after each page scan to ensure low memory footprints.

📱 Example App #

Check the example/ folder for a complete sample Flutter app demonstrating PDF picking, asset scanning, and real-time result listing.

To run the example app:

cd example
flutter run

🤝 Contributing #

Contributions, issues, and feature requests are welcome! Feel free to check the issues page.

📄 License #

This project is licensed under the BSD 3-Clause License - see the LICENSE file for details.