spectacular_barcode

A Flutter barcode and QR code scanner built with MethodChannel and native code:

Android — CameraX + ML Kit (Kotlin)
iOS — AVFoundation + Vision (Swift)

Includes a live camera preview, scan-window overlay, torch, zoom, and camera switching.

Features

Live camera preview via Flutter texture
Barcode / QR detection on device
Visible scan area (cutout overlay)
Torch toggle and zoom
Front / back camera switch
Same Dart API on Android and iOS

Supported platforms

Platform	Status
Android	Supported (minSdk 24)
iOS	Supported (iOS 13+)

Installation

Add the dependency to your pubspec.yaml:

dependencies:
  spectacular_barcode:
    path: ../spectacular_barcode   # or git / pub.dev when published

Then run:

flutter pub get

Permissions

Android

The plugin declares the camera permission. Ensure your app merges it (already included by the plugin):

<uses-permission android:name="android.permission.CAMERA" />

Runtime permission is requested when the scanner starts.

iOS

Add to ios/Runner/Info.plist:

<key>NSCameraUsageDescription</key>
<string>Camera access is required to scan barcodes and QR codes.</string>

Quick start

import 'package:flutter/material.dart';
import 'package:spectacular_barcode/spectacular_barcode.dart';

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

  @override
  State<ScannerPage> createState() => _ScannerPageState();
}

class _ScannerPageState extends State<ScannerPage> {
  final _controller = SpectacularBarcodeController();
  String? _value;

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SpectacularBarcodeView(
        controller: _controller,
        onDetect: (capture) {
          if (capture.barcodes.isEmpty) return;
          setState(() {
            _value = capture.barcodes.first.rawValue;
          });
          _controller.stop();
        },
      ),
      bottomNavigationBar: SafeArea(
        child: Padding(
          padding: const EdgeInsets.all(16),
          child: Text(_value ?? 'Scan a barcode'),
        ),
      ),
    );
  }
}

Scan window overlay

Pass a scanWindow to limit detection and show a framed cutout:

LayoutBuilder(
  builder: (context, constraints) {
    final size = constraints.biggest;
    final side = size.width * 0.72;
    final scanWindow = Rect.fromCenter(
      center: size.center(Offset.zero),
      width: side,
      height: side,
    );

    return SpectacularBarcodeView(
      controller: controller,
      scanWindow: scanWindow,
      overlayBuilder: (context, constraints) {
        return ScanWindowOverlay(
          controller: controller,
          scanWindow: scanWindow,
        );
      },
      onDetect: (capture) {
        // handle result
      },
    );
  },
);

Controller API

Method	Description
`start()`	Request permission and start the camera
`stop()`	Stop the camera
`pause()`	Pause the camera
`toggleTorch()`	Toggle flashlight
`setZoomScale(double)`	Zoom between `0.0` and `1.0`
`resetZoomScale()`	Reset zoom
`switchCamera()`	Switch front / back
`barcodes`	Stream of `BarcodeCapture` events

Example app

cd example
flutter pub get
flutter run

The example shows a full-screen scanner with a scan area, then displays the scanned value with Copy and Scan again.

Architecture

Flutter talks to native code over MethodChannel / EventChannel:

Method: com.zequetech.spectacular_barcode/scanner/method
Event: com.zequetech.spectacular_barcode/scanner/event

Methods: state, request, start, stop, pause, toggleTorch, setScale, resetScale, updateScanWindow

License

MIT License. See LICENSE.