qrscanner.dart

  MobileScannerController cameraController = MobileScannerController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Mobile Scanner'),
        actions: [
          IconButton(
            color: Colors.white,
            icon: ValueListenableBuilder(
              valueListenable: cameraController.torchState,
              builder: (context, state, child) {
                switch (state as TorchState) {
                  case TorchState.off:
                    return const Icon(Icons.flash_off, color: Colors.grey);
                  case TorchState.on:
                    return const Icon(Icons.flash_on, color: Colors.yellow);
                }
              },
            ),
            iconSize: 32.0,
            onPressed: () => cameraController.toggleTorch(),
          ),
          IconButton(
            color: Colors.white,
            icon: ValueListenableBuilder(
              valueListenable: cameraController.cameraFacingState,
              builder: (context, state, child) {
                switch (state as CameraFacing) {
                  case CameraFacing.front:
                    return const Icon(Icons.camera_front);
                  case CameraFacing.back:
                    return const Icon(Icons.camera_rear);
                }
              },
            ),
            iconSize: 32.0,
            onPressed: () => cameraController.switchCamera(),
          ),
          const SizedBox(width: 20)
        ],
      ),
      body: MobileScanner(
          allowDuplicates: false,
          controller: cameraController,
          onDetect: (barcode, args) {
            final String? code = barcode.rawValue;
            debugPrint('Barcode found! $code');
          }),
    );
  }