Easy Blue Printer #

The Easy Blue Printer plugin allows seamless integration of Bluetooth printers in a Flutter app, enabling the scanning, connection, and printing functionality.

Features #

• Scan nearby Bluetooth devices.
• Connect and disconnect from Bluetooth printers.
• Print text data with configurable options such as font size, alignment, and bold text.
• Print empty lines for formatting.

Installation #

1. Add easy_blue_printer to your pubspec.yaml file:

dependencies:
  easy_blue_printer: ^latest_version

2. Run flutter pub get to install the package.

Permissions #

For Android #

To enable Bluetooth functionality on Android, you need to add the following permissions in your AndroidManifest.xml:

<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
<uses-permission android:name="android.permission.BLUETOOTH_CONNECT"/>
<uses-permission android:name="android.permission.BLUETOOTH_SCAN" />

For iOS #

For iOS, you need to add the following entries to your Info.plist file:

<key>NSBluetoothAlwaysUsageDescription</key>
<string>O aplicativo precisa de acesso ao Bluetooth para conectar-se a dispositivos próximos.</string>
<key>NSBluetoothPeripheralUsageDescription</key>
<string>O aplicativo precisa acessar o Bluetooth para comunicação com dispositivos externos.</string>
<key>NSBluetoothAlwaysUsageDescription</key>
<string>O aplicativo usa Bluetooth para se conectar a dispositivos compatíveis.</string>
<key>NSLocalNetworkUsageDescription</key>
<string>O aplicativo precisa acessar a rede local para comunicação com dispositivos Bluetooth.</string>

Usage #

1. Import the Library #

To start using the Easy Blue Printer plugin, import the library:

import 'package:easy_blue_printer/easy_blue_printer.dart';

2. BluetoothController Implementation #

You can create a controller class (BluetoothController) to manage the scanning, connecting, and printing functionality:

class BluetoothController {
  final EasyBluePrinter _easyBluePrinterPlugin = EasyBluePrinter();
  final StreamController<List<BluetoothDevice>> _devicesStream =
      StreamController<List<BluetoothDevice>>.broadcast();

  Stream<List<BluetoothDevice>> get devicesStream => _devicesStream.stream;

  void startScan() {
    _easyBluePrinterPlugin.scanDevices().then((devices) {
      _devicesStream.add(devices);
    });
  }

  void stopScan() {
    _devicesStream.close();
  }

  Future<bool> connectToDevice(BluetoothDevice device) async {
    return await _easyBluePrinterPlugin.connectToDevice(device);
  }

  Future<bool> disconnectFromDevice() async {
    return await _easyBluePrinterPlugin.disconnectFromDevice();
  }

  Future<bool> printData({
    required String data,
    required FS fontSize,
    required TA textAlign,
    required bool bold,
  }) async {
    return await _easyBluePrinterPlugin.printData(
      data: data,
      fontSize: fontSize,
      textAlign: textAlign,
      bold: bold,
    );
  }

  Future<void> printEmptyLine({required int callTimes}) async {
    await _easyBluePrinterPlugin.printEmptyLine(callTimes: callTimes);
  }
}

3. Main Application #

The main application can use the BluetoothController to manage Bluetooth devices, scan for them, and send print commands. Here's an example of the main app structure:

void main() {
  runApp(const MyApp());
}

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

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  final BluetoothController bluetoothController = BluetoothController();

  @override
  void initState() {
    super.initState();
    bluetoothController.startScan(); // Start scanning when the screen is loaded
  }

  @override
  void dispose() {
    bluetoothController.stopScan(); // Stop scanning when the screen is discarded
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Easy Blue Printer Example'),
        ),
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              StreamBuilder<List<BluetoothDevice>>(
                stream: bluetoothController.devicesStream,
                builder: (context, snapshot) {
                  if (snapshot.connectionState == ConnectionState.waiting) {
                    return CircularProgressIndicator();
                  }

                  if (!snapshot.hasData || snapshot.data!.isEmpty) {
                    return Text('Nenhum dispositivo encontrado');
                  }

                  return Expanded(
                    child: ListView.builder(
                      itemCount: snapshot.data!.length,
                      itemBuilder: (context, index) {
                        final device = snapshot.data![index];

                        return ListTile(
                          title: Text(device.name),
                          subtitle:
                              Text('${device.address} - ${device.connected}'),
                          onTap: () async {
                            final connected = await bluetoothController
                                .connectToDevice(device);

                            device.setConnected(connected);

                            setState(() {});
                          },
                        );
                      },
                    ),
                  );
                },
              ),
              ElevatedButton(
                onPressed: () async {
                  await bluetoothController.printData(
                    data: 'Hello, World!',
                    fontSize: FS.normal,
                    textAlign: TA.center,
                    bold: false,
                  );

                  await bluetoothController.printEmptyLine(callTimes: 5);
                },
                child: const Text('Imprimir'),
              ),
              SizedBox(height: 16),
              ElevatedButton(
                onPressed: () async {
                  await bluetoothController.disconnectFromDevice();
                },
                child: const Text('Desconectar'),
              ),
              SizedBox(height: 16),
            ],
          ),
        ),
      ),
    );
  }
}

License #

This project is licensed under the MIT License.

With Easy Blue Printer, integrating Bluetooth printers into your Flutter app is simple and efficient. Enjoy printing directly from your mobile device with just a few lines of code!