hardware_barcode_scanner 0.1.1

Unified hardware scanner input for HID scanners and rugged Android broadcast scanners.

hardware_barcode_scanner

Unified scanner input for Flutter apps that support HID keyboard scanners and rugged Android devices that deliver scans through broadcast intents.

When to use this package

• The barcodes are read by dedicated scanner hardware — USB, Bluetooth, or built-in — rather than by the device camera.
• The app has to support both HID keyboard scanners and rugged Android devices that deliver scans through broadcast intents, without branching on the transport.
• No runtime permission, manifest entry, or camera access is wanted: the plugin registers its broadcast receiver only while a controller is started.
• Scanner input has to keep working while the UI has focus elsewhere, with duplicate suppression and format filtering handled for you.

Not a fit if the barcodes are read from the device camera — this package never decodes an image, it only normalizes input that scanner hardware has already decoded.

Features

• USB, Bluetooth, and built-in HID scanners through Flutter keyboard events.
• Configurable Android broadcast presets for common rugged-device vendors.
• A single stream of normalized scan results, regardless of transport.
• Diagnostic events for ignored scans, duplicates, lifecycle changes, and platform errors.
• Format filtering, regular-expression validation, pause/resume, and duplicate suppression.
• Unicode text input by default, with an opt-in physical US-keyboard mode.

Platform support

Platform	HID keyboard input	Native scanner broadcasts
Android	Yes	Yes
iOS	Yes	Not applicable

Other Flutter platforms can use the Dart keyboard path when the platform provides Flutter hardware-key events. The bundled native plugin targets Android and iOS.

The package requires Flutter 3.19 or later and Dart 3.3 or later because it uses Flutter's modern KeyEvent and HardwareKeyboard APIs. The native projects support Android API 21+ and iOS 12+; newer Flutter releases can impose higher deployment targets on the consuming app.

Installation

Add the package to your app:

flutter pub add hardware_barcode_scanner

No Android permission or manifest entry is required. The plugin registers its broadcast receiver only while a controller is started.

Usage

Create and retain one controller, listen to accepted scans, and place the widget around the part of the UI that should keep scanner focus:

import 'dart:async';

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

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

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

class _ScannerPageState extends State<ScannerPage> {
  final _scanner = HardwareScannerController();
  StreamSubscription<HardwareScanResult>? _subscription;
  String _lastValue = 'Scan a barcode';

  @override
  void initState() {
    super.initState();
    _subscription = _scanner.scans.listen((scan) {
      setState(() => _lastValue = scan.value);
    });
  }

  @override
  void dispose() {
    unawaited(_subscription?.cancel());
    unawaited(_scanner.dispose());
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return HardwareScannerWidget(
      controller: _scanner,
      child: Center(child: Text(_lastValue)),
    );
  }
}

HardwareScannerWidget starts its controller by default. Set startOnInit to false if your application manages start() itself. A widget does not stop a shared controller unless stopOnDispose is enabled; the controller owner should always call dispose().

Filtering and diagnostics

final scanner = HardwareScannerController(
  options: HardwareScannerOptions(
    supportedFormats: {
      HardwareScannerFormat.qrCode,
      HardwareScannerFormat.code128,
    },
    acceptUnknownFormat: true,
    validCharacterPattern: RegExp(r'^[A-Za-z0-9:._-]+$'),
    duplicateSuppressionWindow: const Duration(milliseconds: 750),
  ),
);

scanner.events.listen((event) {
  if (event.type == HardwareScannerEventType.ignored) {
    debugPrint('Ignored scan: ${event.reason}');
  }
});

A HID scanner never reports a barcode format. It presents itself as a keyboard and sends the decoded characters, so format is always HardwareScannerFormat.unknown and rawFormat is always null for those scans. This is not a limitation of the package — there is nothing in a keystroke stream to read a symbology from. Only Android broadcast scanners can report a format, and only when the scanner service includes one.

Two consequences worth knowing before you configure filtering:

• supportedFormats has no effect on HID scans. They carry no format, so nothing is there to match.
• acceptUnknownFormat: false rejects every HID scan. It is on by default for exactly this reason. Turn it off only in a deployment that is exclusively broadcast scanners.

Reported native formats are normalized and checked against supportedFormats. Surrounding whitespace is removed from accepted values. Anchor validCharacterPattern with ^ and $ when the whole value must match.

Call pause() before processing a scan if subsequent scanner input should be ignored temporarily, then call resume() when processing is complete.

Advanced usage

The following live in doc/recipes.md:

• Unicode and keyboard layouts — preserving Unicode values, and the opt-in physical US-keyboard mode for ASCII-only scanners.
• Android broadcast scanners — the bundled vendor presets, defining your own, and why broadcasts are not an authenticated transport.
• Optional Chainway SDK — reflection-based configuration for devices that need it.
• Logging — diagnostics, and the data-handling caveat.

See the example for a complete runnable app.