barcode-scan2-scanning

# barcode_scan2 Barcode & QR Scanning Guide `barcode_scan2` is a Flutter camera plugin for scanning 2D barcodes and QR codes with sound null safety support, built-in flashlight control, and customizable scanning options. ## Guidelines - **Native Permission Configuration (Mandatory)**: - **iOS (`Info.plist`)**: Always add `NSCameraUsageDescription` with a user-facing explanation: ```xml <key>NSCameraUsageDescription</key> <string>Camera access is required to scan barcodes and QR codes.</string> ``` - **Android (`AndroidManifest.xml`)**: Ensure camera permission is declared: ```xml <uses-permission android:name="android.permission.CAMERA" /> ``` - **Initiating Scan**: - Call `final result = await BarcodeScanner.scan(options: ...);`. - **Handling Scan Results**: - Check `result.type`: - `ResultType.Barcode`: Successful scan. Access `result.rawContent` and `result.format`. - `ResultType.Cancelled`: User dismissed or backed out of the scanner. Do not treat as an error. - `ResultType.Error`: Access `result.rawContent` for error diagnostic information. - **Handling Permission Exceptions**: - Wrap `BarcodeScanner.scan()` in a `try-catch` block catching `PlatformException`. - Check `if (e.code == BarcodeScanner.cameraAccessDenied)` to present a permissions dialog directing the user to system settings. - **Format Restrictions & Performance**: - When scanning only QR codes, set `restrictFormat: [BarcodeFormat.qr]` in `ScanOptions` to speed up recognition. ## Examples ### 1. Basic Barcode / QR Code Scanner ```dart import 'package:barcode_scan2/barcode_scan2.dart'; import 'package:flutter/material.dart'; import 'package:flutter/services.dart'; Future<String?> scanCode(BuildContext context) async { try { final result = await BarcodeScanner.scan( options: const ScanOptions( strings: { 'cancel': 'Cancel', 'flash_on': 'Flash on', 'flash_off': 'Flash off', }, restrictFormat: [BarcodeFormat.qr], useCamera: -1, // Back camera default autoEnableFlash: false, android: AndroidOptions( aspectTolerance: 0.5, useAutoFocus: true, ), ), ); switch (result.type) { case ResultType.Barcode: return result.rawContent; case ResultType.Cancelled: return null; case ResultType.Error: ScaffoldMessenger.of(context).showSnackBar( SnackBar(content: Text('Scan error: ${result.rawContent}')), ); return null; } } on PlatformException catch (e) { if (e.code == BarcodeScanner.cameraAccessDenied) { ScaffoldMessenger.of(context).showSnackBar( const SnackBar(content: Text('Camera permission was denied.')), ); } else { ScaffoldMessenger.of(context).showSnackBar( SnackBar(content: Text('Unexpected error: ${e.message}')), ); } return null; } } ``` ## Common Pitfalls & Anti-Patterns - ❌ **Anti-pattern**: Forgetting `NSCameraUsageDescription` in `ios/Runner/Info.plist`, causing immediate app crash on iOS when camera opens. - ✔️ **Correct**: Add the description string before calling `BarcodeScanner.scan()`. - ❌ **Anti-pattern**: Assuming `result.rawContent` is non-empty without checking `result.type == ResultType.Barcode`. - ✔️ **Correct**: Always verify `result.type` first.