easy_blue_printer 1.4.6

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

example/lib/main.dart

import 'package:easy_blue_printer/easy_blue_printer.dart';
import 'package:easy_blue_printer_example/bluetooth_controller.dart';
import 'package:flutter/material.dart';

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

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Easy Blue Printer',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        colorSchemeSeed: Colors.blue,
        useMaterial3: true,
      ),
      home: const PrinterPage(),
    );
  }
}

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

  @override
  State<PrinterPage> createState() => _PrinterPageState();
}

class _PrinterPageState extends State<PrinterPage> {
  final BluetoothController _controller = BluetoothController();

  BluetoothDevice? _connectedDevice;
  bool _isScanning = false;
  bool _isLoading = false;
  bool _hasScanned = false;
  PaperConfig _paperConfig = PaperConfig.roll58mm;

  bool get _isConnected => _connectedDevice != null;

  Future<void> _scan() async {
    setState(() {
      _isScanning = true;
      _hasScanned = true;
    });
    await _controller.startScan();
    if (mounted) setState(() => _isScanning = false);
  }

  Future<void> _connect(BluetoothDevice device) async {
    setState(() => _isLoading = true);
    try {
      final success = await _controller.connectToDevice(device);
      if (success) {
        setState(() => _connectedDevice = device);
        _showSnackBar('Connected to ${device.name}', isError: false);
      } else {
        _showSnackBar('Failed to connect to ${device.name}', isError: true);
      }
    } catch (e) {
      _showSnackBar('Error: $e', isError: true);
    } finally {
      if (mounted) setState(() => _isLoading = false);
    }
  }

  Future<void> _disconnect() async {
    setState(() => _isLoading = true);
    try {
      final success = await _controller.disconnectFromDevice();
      if (success) {
        final name = _connectedDevice?.name ?? 'device';
        setState(() => _connectedDevice = null);
        _showSnackBar('Disconnected from $name', isError: false);
      } else {
        _showSnackBar('Failed to disconnect', isError: true);
      }
    } catch (e) {
      _showSnackBar('Error: $e', isError: true);
    } finally {
      if (mounted) setState(() => _isLoading = false);
    }
  }

  Future<void> _printText() async {
    setState(() => _isLoading = true);
    try {
      final success = await _controller.printData(
        data: 'Sucesso voce configurou a impressora!!',
        fontSize: FS.medium,
        textAlign: TA.center,
        bold: false,
      );
      await _controller.printEmptyLine(callTimes: 5);
      _showSnackBar(success ? 'Text printed successfully' : 'Print failed',
          isError: !success);
    } catch (e) {
      _showSnackBar('Print error: $e', isError: true);
    } finally {
      if (mounted) setState(() => _isLoading = false);
    }
  }

  Future<void> _printImage() async {
    setState(() => _isLoading = true);
    try {
      final success = await _controller.printImage(
        path: 'assets/images/gremio.png',
        textAlign: TA.center,
      );
      _showSnackBar(success ? 'Image printed successfully' : 'Print failed',
          isError: !success);
    } catch (e) {
      _showSnackBar('Print error: $e', isError: true);
    } finally {
      if (mounted) setState(() => _isLoading = false);
    }
  }

  Future<void> _printFullTest() async {
    setState(() => _isLoading = true);
    try {
      const largeText =
          'Este e um texto longo para testar a impressao de grandes volumes de dados. '
          'O package deve dividir automaticamente em chunks e enviar de forma sequencial '
          'sem travar a impressora ou corromper os caracteres impressos. '
          'Linha 1. Linha 2. Linha 3. Linha 4. Linha 5. Fim do texto grande.';

      await _controller.printData(
        data: largeText,
        fontSize: FS.normal,
        textAlign: TA.left,
        bold: false,
      );
      await _controller.printEmptyLine(callTimes: 2);
      await _controller.printImage(
        path: 'assets/images/gremio.png',
        textAlign: TA.center,
      );
      await _controller.printEmptyLine(callTimes: 2);
      await _controller.printData(
        data: largeText,
        fontSize: FS.normal,
        textAlign: TA.left,
        bold: false,
      );
      await _controller.printEmptyLine(callTimes: 5);
      _showSnackBar('Full test printed successfully', isError: false);
    } catch (e) {
      _showSnackBar('Print error: $e', isError: true);
    } finally {
      if (mounted) setState(() => _isLoading = false);
    }
  }

  Future<void> _onPaperConfigChanged(PaperConfig config) async {
    setState(() => _paperConfig = config);
    try {
      await _controller.configurePrinter(config);
    } catch (e) {
      _showSnackBar('Error configuring printer: $e', isError: true);
    }
  }

  Future<void> _testConnection() async {
    setState(() => _isLoading = true);
    try {
      final connected = await _controller.isConnected();
      _showSnackBar(
          connected ? 'Printer is connected' : 'Printer is not connected',
          isError: !connected);
      if (!connected && _connectedDevice != null) {
        setState(() => _connectedDevice = null);
      }
    } catch (e) {
      _showSnackBar('Error: $e', isError: true);
    } finally {
      if (mounted) setState(() => _isLoading = false);
    }
  }

  void _showSnackBar(String message, {required bool isError}) {
    if (!mounted) return;
    ScaffoldMessenger.of(context).hideCurrentSnackBar();
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(
        content: Text(message),
        backgroundColor: isError ? Colors.red.shade700 : Colors.green.shade700,
        behavior: SnackBarBehavior.floating,
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(8)),
        margin: const EdgeInsets.all(16),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;

    return Scaffold(
      appBar: AppBar(
        title: const Text('Easy Blue Printer'),
        actions: [
          Padding(
            padding: const EdgeInsets.only(right: 16),
            child: Row(
              mainAxisSize: MainAxisSize.min,
              children: [
                Container(
                  width: 10,
                  height: 10,
                  decoration: BoxDecoration(
                    shape: BoxShape.circle,
                    color: _isConnected ? Colors.green : Colors.grey,
                  ),
                ),
                const SizedBox(width: 8),
                Text(
                  _isConnected ? 'Connected' : 'Disconnected',
                  style: Theme.of(context).textTheme.bodySmall,
                ),
              ],
            ),
          ),
        ],
      ),
      body: SafeArea(
        top: false,
        child: SingleChildScrollView(
          child: Column(
            children: [
              // Device list section
              Padding(
                padding: const EdgeInsets.fromLTRB(16, 16, 16, 0),
                child: Card(
                  clipBehavior: Clip.antiAlias,
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.stretch,
                    mainAxisSize: MainAxisSize.min,
                    children: [
                      Padding(
                        padding: const EdgeInsets.fromLTRB(16, 12, 8, 4),
                        child: Row(
                          children: [
                            Icon(Icons.bluetooth,
                                size: 20, color: colorScheme.primary),
                            const SizedBox(width: 8),
                            Text('Paired Devices',
                                style: Theme.of(context).textTheme.titleMedium),
                            const Spacer(),
                            IconButton(
                              icon: _isScanning
                                  ? SizedBox(
                                      width: 20,
                                      height: 20,
                                      child: CircularProgressIndicator(
                                          strokeWidth: 2),
                                    )
                                  : const Icon(Icons.refresh),
                              tooltip: 'Scan devices',
                              onPressed: _isScanning ? null : _scan,
                            ),
                          ],
                        ),
                      ),
                      const Divider(height: 1),
                      ConstrainedBox(
                        constraints: const BoxConstraints(maxHeight: 240),
                        child: _buildDeviceList(),
                      ),
                    ],
                  ),
                ),
              ),

              // Actions section
              Padding(
                padding: const EdgeInsets.all(16),
                child: Card(
                  child: Padding(
                    padding: const EdgeInsets.all(16),
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.stretch,
                      children: [
                        Row(
                          children: [
                            Icon(Icons.tune,
                                size: 20, color: colorScheme.primary),
                            const SizedBox(width: 8),
                            Text('Actions',
                                style: Theme.of(context).textTheme.titleMedium),
                          ],
                        ),
                        const SizedBox(height: 12),
                        Row(
                          children: [
                            Icon(Icons.receipt_long,
                                size: 18, color: colorScheme.onSurfaceVariant),
                            const SizedBox(width: 8),
                            Text('Paper roll:',
                                style: Theme.of(context).textTheme.bodyMedium),
                            const SizedBox(width: 12),
                            SegmentedButton<PaperConfig>(
                              segments: const [
                                ButtonSegment(
                                  value: PaperConfig.roll58mm,
                                  label: Text('58 mm'),
                                ),
                                ButtonSegment(
                                  value: PaperConfig.roll80mm,
                                  label: Text('80 mm'),
                                ),
                              ],
                              selected: {_paperConfig},
                              onSelectionChanged: (selection) =>
                                  _onPaperConfigChanged(selection.first),
                              style: const ButtonStyle(
                                visualDensity: VisualDensity.compact,
                              ),
                            ),
                          ],
                        ),
                        const SizedBox(height: 12),
                        Wrap(
                          spacing: 8,
                          runSpacing: 8,
                          children: [
                            FilledButton.icon(
                              onPressed:
                                  _isScanning || _isLoading ? null : _scan,
                              icon: const Icon(Icons.search),
                              label: const Text('Scan'),
                            ),
                            FilledButton.tonalIcon(
                              onPressed: _isConnected && !_isLoading
                                  ? _printText
                                  : null,
                              icon: const Icon(Icons.print),
                              label: const Text('Print Text'),
                            ),
                            FilledButton.tonalIcon(
                              onPressed: _isConnected && !_isLoading
                                  ? _printImage
                                  : null,
                              icon: const Icon(Icons.image),
                              label: const Text('Print Image'),
                            ),
                            FilledButton.tonalIcon(
                              onPressed: _isConnected && !_isLoading
                                  ? _printFullTest
                                  : null,
                              icon: const Icon(Icons.receipt),
                              label: const Text('Full Test'),
                            ),
                            OutlinedButton.icon(
                              onPressed: !_isLoading ? _testConnection : null,
                              icon: const Icon(Icons.wifi_tethering),
                              label: const Text('Test'),
                            ),
                            if (_isConnected)
                              FilledButton.icon(
                                onPressed: _isLoading ? null : _disconnect,
                                icon: const Icon(Icons.link_off),
                                label: const Text('Disconnect'),
                                style: FilledButton.styleFrom(
                                  backgroundColor: colorScheme.error,
                                  foregroundColor: colorScheme.onError,
                                ),
                              ),
                          ],
                        ),
                      ],
                    ),
                  ),
                ),
              ),
            ],
          ),
        ),
      ),
      // Loading overlay
      bottomNavigationBar: _isLoading ? const LinearProgressIndicator() : null,
    );
  }

  Widget _buildDeviceList() {
    if (!_hasScanned) {
      return Center(
        child: Padding(
          padding: const EdgeInsets.all(32),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              Icon(Icons.bluetooth_searching,
                  size: 48, color: Colors.grey.shade400),
              const SizedBox(height: 16),
              Text(
                'Tap Scan to find paired devices',
                style: TextStyle(color: Colors.grey.shade600),
              ),
            ],
          ),
        ),
      );
    }

    return StreamBuilder<List<BluetoothDevice>>(
      stream: _controller.devicesStream,
      builder: (context, snapshot) {
        if (_isScanning) {
          return const Center(child: CircularProgressIndicator());
        }

        if (!snapshot.hasData || snapshot.data!.isEmpty) {
          return Center(
            child: Padding(
              padding: const EdgeInsets.all(32),
              child: Column(
                mainAxisSize: MainAxisSize.min,
                children: [
                  Icon(Icons.devices, size: 48, color: Colors.grey.shade400),
                  const SizedBox(height: 16),
                  Text(
                    'No paired devices found',
                    style: TextStyle(color: Colors.grey.shade600),
                  ),
                ],
              ),
            ),
          );
        }

        final devices = snapshot.data!;
        return ListView.separated(
          itemCount: devices.length,
          separatorBuilder: (_, __) => const Divider(height: 1, indent: 56),
          itemBuilder: (context, index) {
            final device = devices[index];
            final isThisConnected = _connectedDevice?.address == device.address;

            return ListTile(
              leading: Icon(
                Icons.bluetooth,
                color: isThisConnected ? Colors.green : null,
              ),
              title: Text(
                device.name,
                style: TextStyle(
                  fontWeight:
                      isThisConnected ? FontWeight.bold : FontWeight.normal,
                ),
              ),
              subtitle: Text(device.address),
              trailing: isThisConnected
                  ? Chip(
                      label: const Text('Connected'),
                      backgroundColor: Colors.green.shade50,
                      side: BorderSide(color: Colors.green.shade200),
                      labelStyle:
                          TextStyle(color: Colors.green.shade700, fontSize: 12),
                    )
                  : IconButton(
                      icon: const Icon(Icons.arrow_forward_ios, size: 16),
                      onPressed: _isLoading ? null : () => _connect(device),
                    ),
              onTap: _isLoading
                  ? null
                  : isThisConnected
                      ? null
                      : () => _connect(device),
            );
          },
        );
      },
    );
  }
}