drago_blue_printer 1.0.0 
drago_blue_printer: ^1.0.0 copied to clipboard
A Flutter plugin for connecting to thermal printer via bluetooth
import 'dart:async';
import 'package:example/testprint.dart';
import 'package:flutter/material.dart';
import 'package:drago_blue_printer/drago_blue_printer.dart';
void main() => runApp(const MyApp());
class MyApp extends StatelessWidget {
const MyApp({super.key});
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Drago Blue Printer',
debugShowCheckedModeBanner: false,
theme: ThemeData(
useMaterial3: true,
colorSchemeSeed: const Color(0xFF1565C0),
brightness: Brightness.light,
),
darkTheme: ThemeData(
useMaterial3: true,
colorSchemeSeed: const Color(0xFF1565C0),
brightness: Brightness.dark,
),
home: const BluetoothPrinterPage(),
);
}
}
// ---------------------------------------------------------------------------
// Main Page
// ---------------------------------------------------------------------------
class BluetoothPrinterPage extends StatefulWidget {
const BluetoothPrinterPage({super.key});
@override
State<BluetoothPrinterPage> createState() => _BluetoothPrinterPageState();
}
class _BluetoothPrinterPageState extends State<BluetoothPrinterPage>
with SingleTickerProviderStateMixin {
final _bluetooth = DragoBluePrinter.instance;
final _testPrint = TestPrint();
List<BluetoothDevice> _pairedDevices = [];
final List<BluetoothDevice> _scannedDevices = [];
BluetoothDevice? _selectedDevice;
bool _connected = false;
bool _isLoading = false;
bool _isConnecting = false;
bool _isPrinting = false;
bool _isScanning = false;
StreamSubscription<BluetoothDevice>? _scanSub;
StreamSubscription<int?>? _stateSub;
late final AnimationController _scanAnimCtrl;
@override
void initState() {
super.initState();
_scanAnimCtrl = AnimationController(
vsync: this,
duration: const Duration(seconds: 2),
);
_loadDevices();
_listenState();
}
@override
void dispose() {
_scanSub?.cancel();
_stateSub?.cancel();
_scanAnimCtrl.dispose();
super.dispose();
}
// -- Bluetooth state listener ---------------------------------------------
void _listenState() {
_stateSub = _bluetooth.onStateChanged().listen((state) {
if (!mounted) return;
switch (state) {
case DragoBluePrinter.CONNECTED:
setState(() {
_connected = true;
_isConnecting = false;
});
_showSnack('Connected', icon: Icons.check_circle, isError: false);
break;
case DragoBluePrinter.DISCONNECTED:
case DragoBluePrinter.DISCONNECT_REQUESTED:
setState(() {
_connected = false;
_isConnecting = false;
});
break;
case DragoBluePrinter.STATE_OFF:
case DragoBluePrinter.STATE_TURNING_OFF:
setState(() {
_connected = false;
_isConnecting = false;
});
_showSnack('Bluetooth turned off', icon: Icons.bluetooth_disabled);
break;
default:
break;
}
});
}
// -- Load bonded devices --------------------------------------------------
Future<void> _loadDevices() async {
setState(() => _isLoading = true);
try {
_pairedDevices = await _bluetooth.getBondedDevices();
} catch (e) {
debugPrint('getBondedDevices error: $e');
}
if (mounted) setState(() => _isLoading = false);
}
// -- Scan -----------------------------------------------------------------
void _toggleScan() {
_isScanning ? _stopScan() : _startScan();
}
void _startScan() {
setState(() {
_isScanning = true;
_scannedDevices.clear();
});
_scanAnimCtrl.repeat();
_scanSub?.cancel();
_scanSub = _bluetooth.scan().listen((device) {
final isDuplicate =
_pairedDevices.any((d) => d.address == device.address) ||
_scannedDevices.any((d) => d.address == device.address);
if (!isDuplicate && mounted) {
setState(() => _scannedDevices.add(device));
}
});
Future.delayed(const Duration(seconds: 20), _stopScan);
}
void _stopScan() {
_scanSub?.cancel();
if (mounted) {
_scanAnimCtrl.stop();
_scanAnimCtrl.reset();
setState(() => _isScanning = false);
}
}
// -- Connect / Disconnect -------------------------------------------------
Future<void> _connect(BluetoothDevice device) async {
if (_isConnecting) return;
setState(() {
_selectedDevice = device;
_isConnecting = true;
});
try {
final alreadyConnected = await _bluetooth.isConnected ?? false;
if (!alreadyConnected) {
await _bluetooth.connect(device);
}
} catch (e) {
if (mounted) {
setState(() => _isConnecting = false);
_showSnack('Connection failed: $e');
}
}
}
Future<void> _disconnect() async {
try {
await _bluetooth.disconnect();
} catch (_) {}
if (mounted) setState(() => _connected = false);
}
// -- Pair -----------------------------------------------------------------
Future<void> _pairDevice(BluetoothDevice device) async {
try {
await _bluetooth.pairDevice(device);
await Future.delayed(const Duration(seconds: 2));
_loadDevices();
_showSnack('Pairing requested', icon: Icons.link, isError: false);
} catch (e) {
_showSnack('Pairing failed: $e');
}
}
// -- Print ----------------------------------------------------------------
Future<void> _printReceipt() async {
if (_isPrinting) return;
setState(() => _isPrinting = true);
try {
await _testPrint.sampleBatch();
if (mounted) {
_showSnack('Print sent!', icon: Icons.print, isError: false);
}
} catch (e) {
if (mounted) _showSnack('Print error: $e');
}
if (mounted) setState(() => _isPrinting = false);
}
Future<void> _printLegacy() async {
if (_isPrinting) return;
setState(() => _isPrinting = true);
try {
await _testPrint.sampleLegacy();
if (mounted) {
_showSnack('Print sent (legacy)!', icon: Icons.print, isError: false);
}
} catch (e) {
if (mounted) _showSnack('Print error: $e');
}
if (mounted) setState(() => _isPrinting = false);
}
// -- Snackbar helper ------------------------------------------------------
void _showSnack(String msg,
{IconData icon = Icons.error_outline, bool isError = true}) {
if (!mounted) return;
final cs = Theme.of(context).colorScheme;
ScaffoldMessenger.of(context).removeCurrentSnackBar();
ScaffoldMessenger.of(context).showSnackBar(SnackBar(
behavior: SnackBarBehavior.floating,
shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12)),
backgroundColor: isError ? cs.errorContainer : cs.primaryContainer,
content: Row(children: [
Icon(icon,
color: isError ? cs.onErrorContainer : cs.onPrimaryContainer,
size: 20),
const SizedBox(width: 10),
Expanded(
child: Text(msg,
style: TextStyle(
color: isError
? cs.onErrorContainer
: cs.onPrimaryContainer)),
),
]),
duration: const Duration(seconds: 3),
));
}
// =========================================================================
// BUILD
// =========================================================================
@override
Widget build(BuildContext context) {
final cs = Theme.of(context).colorScheme;
final isConnected =
_selectedDevice != null && _connected && !_isConnecting;
return Scaffold(
// ── App Bar ──────────────────────────────────────────────────────────
appBar: AppBar(
title: const Text('Drago Blue Printer'),
centerTitle: true,
actions: [
IconButton(
tooltip: 'Refresh paired devices',
icon: const Icon(Icons.refresh_rounded),
onPressed: _loadDevices,
),
const SizedBox(width: 4),
],
),
// ── FAB ──────────────────────────────────────────────────────────────
floatingActionButton: FloatingActionButton.extended(
onPressed: _toggleScan,
icon: _isScanning
? RotationTransition(
turns: _scanAnimCtrl,
child: const Icon(Icons.bluetooth_searching))
: const Icon(Icons.search_rounded),
label: Text(_isScanning ? 'Stop Scan' : 'Scan Nearby'),
),
// ── Body ─────────────────────────────────────────────────────────────
body: _isLoading
? const Center(child: CircularProgressIndicator())
: RefreshIndicator(
onRefresh: _loadDevices,
child: ListView(
padding: const EdgeInsets.fromLTRB(16, 8, 16, 100),
children: [
// ── Status banner ────────────────────────────────────────
_StatusBanner(
connected: isConnected,
deviceName: _selectedDevice?.name,
),
const SizedBox(height: 16),
// ── Action buttons when connected ────────────────────────
if (isConnected) ...[
_SectionHeader(
icon: Icons.receipt_long_rounded, label: 'Actions'),
const SizedBox(height: 8),
_ActionBar(
isPrinting: _isPrinting,
onPrintBatch: _printReceipt,
onPrintLegacy: _printLegacy,
onDisconnect: _disconnect,
),
const SizedBox(height: 24),
],
// ── Paired devices ───────────────────────────────────────
_SectionHeader(
icon: Icons.devices_rounded, label: 'Paired Devices'),
const SizedBox(height: 8),
if (_pairedDevices.isEmpty)
_EmptyHint(
label: 'No paired printers found.',
icon: Icons.print_disabled_rounded),
..._pairedDevices.map((d) => _DeviceTile(
device: d,
isSelected: _selectedDevice?.address == d.address,
isConnected:
_selectedDevice?.address == d.address && _connected,
isConnecting:
_selectedDevice?.address == d.address &&
_isConnecting,
onTap: () => _connect(d),
)),
// ── Scanned devices ──────────────────────────────────────
if (_isScanning || _scannedDevices.isNotEmpty) ...[
const SizedBox(height: 24),
_SectionHeader(
icon: Icons.bluetooth_searching_rounded,
label: 'Nearby Devices',
trailing: _isScanning
? const SizedBox(
width: 14,
height: 14,
child: CircularProgressIndicator(
strokeWidth: 2))
: null),
const SizedBox(height: 8),
if (_scannedDevices.isEmpty && _isScanning)
_EmptyHint(
label: 'Searching…',
icon: Icons.radar_rounded),
..._scannedDevices.map((d) => _ScannedDeviceTile(
device: d,
onPair: () => _pairDevice(d),
)),
],
],
),
),
);
}
}
// ===========================================================================
// Extracted widgets
// ===========================================================================
/// Bluetooth connection status banner at the top.
class _StatusBanner extends StatelessWidget {
const _StatusBanner({required this.connected, this.deviceName});
final bool connected;
final String? deviceName;
@override
Widget build(BuildContext context) {
final cs = Theme.of(context).colorScheme;
return AnimatedContainer(
duration: const Duration(milliseconds: 350),
curve: Curves.easeInOut,
padding: const EdgeInsets.symmetric(horizontal: 20, vertical: 14),
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(16),
gradient: LinearGradient(
colors: connected
? [cs.primaryContainer, cs.primaryContainer.withAlpha(180)]
: [cs.surfaceContainerHighest, cs.surfaceContainerHigh],
),
),
child: Row(children: [
Icon(
connected
? Icons.bluetooth_connected_rounded
: Icons.bluetooth_disabled_rounded,
color: connected ? cs.primary : cs.outline,
size: 28,
),
const SizedBox(width: 14),
Expanded(
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
Text(
connected ? 'Connected' : 'Not Connected',
style: Theme.of(context).textTheme.titleSmall?.copyWith(
fontWeight: FontWeight.w700,
color: connected ? cs.primary : cs.onSurfaceVariant),
),
if (connected && deviceName != null)
Text(deviceName!,
style: Theme.of(context).textTheme.bodySmall?.copyWith(
color: cs.onPrimaryContainer)),
if (!connected)
Text('Select a device below to connect',
style: Theme.of(context)
.textTheme
.bodySmall
?.copyWith(color: cs.outline)),
],
),
),
if (connected)
Container(
width: 10,
height: 10,
decoration: BoxDecoration(
color: Colors.green,
shape: BoxShape.circle,
boxShadow: [
BoxShadow(
color: Colors.green.withAlpha(120),
blurRadius: 6,
spreadRadius: 2)
],
),
),
]),
);
}
}
/// Section header with icon.
class _SectionHeader extends StatelessWidget {
const _SectionHeader(
{required this.icon, required this.label, this.trailing});
final IconData icon;
final String label;
final Widget? trailing;
@override
Widget build(BuildContext context) {
final cs = Theme.of(context).colorScheme;
return Row(children: [
Icon(icon, size: 18, color: cs.primary),
const SizedBox(width: 8),
Text(label,
style: Theme.of(context)
.textTheme
.titleSmall
?.copyWith(fontWeight: FontWeight.w600, color: cs.primary)),
if (trailing != null) ...[const SizedBox(width: 8), trailing!],
]);
}
}
/// Empty-state hint row.
class _EmptyHint extends StatelessWidget {
const _EmptyHint({required this.label, required this.icon});
final String label;
final IconData icon;
@override
Widget build(BuildContext context) {
return Padding(
padding: const EdgeInsets.symmetric(vertical: 24),
child: Center(
child: Column(mainAxisSize: MainAxisSize.min, children: [
Icon(icon, size: 36, color: Theme.of(context).colorScheme.outline),
const SizedBox(height: 8),
Text(label,
style: Theme.of(context)
.textTheme
.bodyMedium
?.copyWith(color: Theme.of(context).colorScheme.outline)),
]),
),
);
}
}
/// Tile for a paired device.
class _DeviceTile extends StatelessWidget {
const _DeviceTile({
required this.device,
required this.isSelected,
required this.isConnected,
required this.isConnecting,
required this.onTap,
});
final BluetoothDevice device;
final bool isSelected;
final bool isConnected;
final bool isConnecting;
final VoidCallback onTap;
@override
Widget build(BuildContext context) {
final cs = Theme.of(context).colorScheme;
return Padding(
padding: const EdgeInsets.only(bottom: 8),
child: Material(
borderRadius: BorderRadius.circular(14),
color: isConnected
? cs.primaryContainer.withAlpha(80)
: cs.surfaceContainerLow,
child: InkWell(
borderRadius: BorderRadius.circular(14),
onTap: isConnected ? null : onTap,
child: Padding(
padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 14),
child: Row(children: [
Container(
width: 44,
height: 44,
decoration: BoxDecoration(
color: isConnected
? cs.primary.withAlpha(30)
: cs.surfaceContainerHighest,
borderRadius: BorderRadius.circular(12),
),
child: Icon(
Icons.print_rounded,
color: isConnected ? cs.primary : cs.onSurfaceVariant,
size: 22,
),
),
const SizedBox(width: 14),
Expanded(
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
Text(device.name ?? 'Unknown Device',
style: Theme.of(context)
.textTheme
.bodyLarge
?.copyWith(fontWeight: FontWeight.w600)),
const SizedBox(height: 2),
Text(device.address ?? '',
style: Theme.of(context)
.textTheme
.bodySmall
?.copyWith(color: cs.outline)),
],
),
),
if (isConnecting)
const SizedBox(
width: 20,
height: 20,
child: CircularProgressIndicator(strokeWidth: 2))
else if (isConnected)
Chip(
label: const Text('Connected'),
labelStyle: TextStyle(
fontSize: 11,
fontWeight: FontWeight.w600,
color: cs.onPrimary),
backgroundColor: cs.primary,
side: BorderSide.none,
visualDensity: VisualDensity.compact,
padding: EdgeInsets.zero,
)
else
Icon(Icons.chevron_right_rounded, color: cs.outline),
]),
),
),
),
);
}
}
/// Tile for a scanned (not-yet-paired) device.
class _ScannedDeviceTile extends StatelessWidget {
const _ScannedDeviceTile({required this.device, required this.onPair});
final BluetoothDevice device;
final VoidCallback onPair;
@override
Widget build(BuildContext context) {
final cs = Theme.of(context).colorScheme;
return Padding(
padding: const EdgeInsets.only(bottom: 8),
child: Material(
borderRadius: BorderRadius.circular(14),
color: cs.surfaceContainerLow,
child: InkWell(
borderRadius: BorderRadius.circular(14),
onTap: onPair,
child: Padding(
padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 14),
child: Row(children: [
Container(
width: 44,
height: 44,
decoration: BoxDecoration(
color: cs.tertiaryContainer.withAlpha(120),
borderRadius: BorderRadius.circular(12),
),
child: Icon(Icons.bluetooth_rounded,
color: cs.tertiary, size: 22),
),
const SizedBox(width: 14),
Expanded(
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
Text(device.name ?? 'Unknown',
style: Theme.of(context)
.textTheme
.bodyLarge
?.copyWith(fontWeight: FontWeight.w600)),
const SizedBox(height: 2),
Text(device.address ?? '',
style: Theme.of(context)
.textTheme
.bodySmall
?.copyWith(color: cs.outline)),
],
),
),
FilledButton.tonal(
onPressed: onPair,
style: FilledButton.styleFrom(
visualDensity: VisualDensity.compact),
child: const Text('Pair'),
),
]),
),
),
),
);
}
}
/// Row of action buttons shown when a printer is connected.
class _ActionBar extends StatelessWidget {
const _ActionBar({
required this.isPrinting,
required this.onPrintBatch,
required this.onPrintLegacy,
required this.onDisconnect,
});
final bool isPrinting;
final VoidCallback onPrintBatch;
final VoidCallback onPrintLegacy;
final VoidCallback onDisconnect;
@override
Widget build(BuildContext context) {
final cs = Theme.of(context).colorScheme;
return Row(children: [
Expanded(
child: FilledButton.icon(
onPressed: isPrinting ? null : onPrintBatch,
icon: isPrinting
? const SizedBox(
width: 16,
height: 16,
child: CircularProgressIndicator(
strokeWidth: 2, color: Colors.white))
: const Icon(Icons.bolt_rounded, size: 20),
label: const Text('Batch Print'),
),
),
const SizedBox(width: 8),
Expanded(
child: FilledButton.tonalIcon(
onPressed: isPrinting ? null : onPrintLegacy,
icon: const Icon(Icons.receipt_long_rounded, size: 20),
label: const Text('Legacy Print'),
),
),
const SizedBox(width: 8),
IconButton.filled(
onPressed: onDisconnect,
icon: const Icon(Icons.link_off_rounded, size: 20),
tooltip: 'Disconnect',
style: IconButton.styleFrom(
backgroundColor: cs.errorContainer,
foregroundColor: cs.onErrorContainer,
),
),
]);
}
}Metadata
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Metadata
A Flutter plugin for connecting to thermal printer via bluetooth
Repository (GitHub)
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License
CPL-1.0 (license)
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