scan_snap #

A simple, customizable, and high-performance QR and barcode scanner widget for Flutter. Easily decode codes from the live camera stream or from image files.

🔄 This package is a maintained and improved fork of the popular scan plugin by chavesgu.

✨ Features #

• Embedded Widget: Embed a live scanner directly into your widget tree with the ScanView widget.
• Customizable: Easily adjust the scan area size and the animated scan line color.
• File Scanning: Decode a QR/barcode from an image file path using Scan.parse().
• Full Camera Control: Pause, resume, and toggle the camera's torch using a ScanController.
• Native Performance: Utilizes CameraX on Android and AVFoundation on iOS for optimal performance.

🚀 Getting Started #

1. Add Dependency #

Add the package to your pubspec.yaml dependencies:

dependencies:
  scan_snap: ^0.0.1 # Replace with the latest version

Then, import the package in your Dart code:

import 'package:scan_snap/scan.dart';

2. Platform Setup #

You need to add permissions to access the camera and photo library.

 iOS

Add the following keys to your ios/Runner/Info.plist file:

<key>NSCameraUsageDescription</key>
<string>This app requires camera access to scan QR codes.</string>
<key>NSPhotoLibraryUsageDescription</key>
<string>This app requires photo library access to scan QR codes from images.</string>

<!-- Required for Flutter Platform Views -->
<key>io.flutter.embedded_views_preview</key>
<true/>

Also, ensure your minSdkVersion in android/app/build.gradle is set to at least 23.

// in android/app/build.gradle
android {
    defaultConfig {
        ...
        minSdkVersion 23
        ...
    }
}

📦 Basic Usage #

Live Scanner with ScanView #

The best way to use the scanner is within a StatefulWidget. Here is a complete example of a scanner screen.

import 'package:flutter/material.dart';
import 'package:scan_snap/scan.dart';

class ScanScreen extends StatefulWidget {
  const ScanScreen({super.key});

  @override
  State<ScanScreen> createState() => _ScanScreenState();
}

class _ScanScreenState extends State<ScanScreen> {
  final ScanController _controller = ScanController();

  void _onCapture(String data) {
    // When a QR is captured, stop the scanner and return to the previous screen
    // with the captured data.
    print('Captured data: $data');
    if (mounted) {
      Navigator.of(context).pop(data);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Scan Code')),
      body: ScanView(
        controller: _controller,
        scanAreaScale: 0.7, // Scan area is 70% of the view size
        scanLineColor: Colors.tealAccent,
        onCapture: _onCapture,
      ),
    );
  }
}

Controlling the Camera #

You can control the camera via the ScanController passed to the ScanView.

// Pause image analysis (the preview stream continues)
controller.pause();

// Resume image analysis
controller.resume();

// Toggle the flashlight on or off
controller.toggleTorchMode();

// Safely shut down and release the camera (used when leaving the screen)
await controller.shutdown();

Scanning from an Image File #

Use the static Scan.parse() method to decode a QR/barcode from a saved image on the device. This is ideal for use with plugins like image_picker.

import 'package:image_picker/image_picker.dart';
import 'package:scan_snap/scan.dart';

// ...

// Example of how to pick an image from the gallery and scan it
Future<void> scanFromGallery() async {
  final ImagePicker picker = ImagePicker();
  final XFile? image = await picker.pickImage(source: ImageSource.gallery);
  
  if (image != null) {
    final String? result = await Scan.parse(image.path);
    if (result != null) {
      print('Result from image: $result');
    }
  }
}

🔐 Proguard Rules (Android) #

If you use Proguard/R8 to shrink and obfuscate your release app, add the following rules to your android/app/proguard-rules.pro file to prevent breaking ZXing and CameraX functionality.

# Rules for ZXing (the decoding library)
-keep class com.google.zxing.** { *; }

# Rules for CameraX (usually not needed but recommended for safety)
-keep public class androidx.camera.core.** {
  public *;
}
-keep class * implements androidx.camera.core.ImageAnalysis$Analyzer {
  *;
}

🙏 Acknowledgements #

This plugin is based on the work of the original scan plugin created by chavesgu.

📄 License #

MIT License