Added PrinterBluetoothManager class

example/blue/lib/main.dart

 import 'dart:async';
 import 'dart:convert';
+import 'package:esc_pos_printer/esc_pos_printer.dart';
 import 'package:flutter/material.dart';
-import 'package:flutter_bluetooth_basic/flutter_bluetooth_basic.dart';
+// import 'package:flutter_bluetooth_basic/flutter_bluetooth_basic.dart';
 import 'package:oktoast/oktoast.dart';
 
 void main() => runApp(MyApp());
@@ -24,111 +25,48 @@ class MyApp extends StatelessWidget {
 class MyHomePage extends StatefulWidget {
   MyHomePage({Key key, this.title}) : super(key: key);
   final String title;
-  // final FlutterBlue flutterBlue = FlutterBlue.instance;
 
   @override
   _MyHomePageState createState() => _MyHomePageState();
 }
 
 class _MyHomePageState extends State<MyHomePage> {
-  BluetoothManager bluetoothManager = BluetoothManager.instance;
-  bool _connected = false;
-  bool _isScanning = false;
-  bool _isPrinting = false;
-  List<BluetoothDevice> _devices = [];
-  StreamSubscription _scanResultsSubscription;
-  StreamSubscription _isScanningSubscription;
+  PrinterBluetoothManager printerManager = PrinterBluetoothManager();
+  List<PrinterBluetooth> _devices = [];
 
-  void _startScanDevices() {
-    setState(() {
-      _devices = [];
-    });
-
-    bluetoothManager.startScan(timeout: Duration(seconds: 4));
+  @override
+  void initState() {
+    super.initState();
 
-    _scanResultsSubscription =
-        bluetoothManager.scanResults.listen((devices) async {
+    printerManager.scanResults.listen((devices) async {
+      print('UI: Devices found ${devices.length}');
       setState(() {
         _devices = devices;
       });
     });
+  }
 
-    _isScanningSubscription =
-        bluetoothManager.isScanning.listen((isScanningCurrent) async {
-      // If isScanning value changed (scan just stopped)
-      if (_isScanning && !isScanningCurrent) {
-        _scanResultsSubscription.cancel();
-        _isScanningSubscription.cancel();
-      }
-      setState(() {
-        _isScanning = isScanningCurrent;
-      });
+  void _startScanDevices() {
+    setState(() {
+      _devices = [];
     });
+    printerManager.startScan(Duration(seconds: 4));
   }
 
   void _stopScanDevices() {
-    bluetoothManager.stopScan();
+    printerManager.stopScan();
   }
 
-  Future _runDelayed(int seconds) {
-    return Future<dynamic>.delayed(Duration(seconds: seconds));
-  }
+  // Future _runDelayed(int seconds) {
+  //   return Future<dynamic>.delayed(Duration(seconds: seconds));
+  // }
 
-  void _testPrint(BluetoothDevice printer) async {
-    const int timeout = 5;
-    if (_isScanning) {
-      showToast('Print failed (scanning in progress)');
-      return;
+  void _testPrint(PrinterBluetooth printer) async {
+    try {
+      printer.printLine('hello');
+    } catch (e) {
+      print(e.toString());
     }
-    if (_isPrinting) {
-      showToast('Print failed (another printing in progress)');
-      return;
-    }
-
-    _isPrinting = true;
-
-    // We have to rescan before connecting, otherwise we can connect only once
-    await bluetoothManager.startScan(timeout: Duration(seconds: 1));
-    await bluetoothManager.stopScan();
-
-    // Connect
-    await bluetoothManager.connect(printer);
-
-    // Subscribe to the events
-    bluetoothManager.state.listen((state) async {
-      switch (state) {
-        case BluetoothManager.CONNECTED:
-          print('********************* CONNECTED');
-          // to avoid double call
-          if (!_connected) {
-            print('@@@@SEND DATA......');
-            final List<int> bytes = latin1.encode('test!\n\n\n').toList();
-            await bluetoothManager.writeData(bytes);
-            showToast('Data sent');
-          }
-          // TODO sending disconnect signal should be event-based
-          _runDelayed(3).then((dynamic v) async {
-            print('@@@@DISCONNECTING......');
-            await bluetoothManager.disconnect();
-            _isPrinting = false;
-          });
-          _connected = true;
-          break;
-        case BluetoothManager.DISCONNECTED:
-          print('********************* DISCONNECTED');
-          _connected = false;
-          break;
-        default:
-          break;
-      }
-    });
-    // Printing timeout
-    _runDelayed(timeout).then((dynamic v) async {
-      if (_isPrinting) {
-        _isPrinting = false;
-        showToast('Print failed');
-      }
-    });
   }
 
   @override
@@ -174,16 +112,24 @@ class _MyHomePageState extends State<MyHomePage> {
               ),
             );
           }),
-      floatingActionButton: _isScanning
-          ? FloatingActionButton(
+      floatingActionButton: StreamBuilder<bool>(
+        stream: printerManager.isScanningStream,
+        initialData: false,
+        builder: (c, snapshot) {
+          if (snapshot.data) {
+            return FloatingActionButton(
               child: Icon(Icons.stop),
               onPressed: _stopScanDevices,
               backgroundColor: Colors.red,
-            )
-          : FloatingActionButton(
+            );
+          } else {
+            return FloatingActionButton(
               child: Icon(Icons.search),
               onPressed: _startScanDevices,
-            ),
+            );
+          }
+        },
+      ),
     );
   }
 }

example/blue/pubspec.yaml

@@ -10,10 +10,8 @@ dependencies:
     sdk: flutter
   cupertino_icons: ^0.1.2
   oktoast: ^2.3.0
-  flutter_bluetooth_basic:
-    git:
-      url: git://github.com/andrey-ushakov/flutter_bluetooth_basic
-      ref: master
+  esc_pos_printer:
+    path: ../../
 
 dev_dependencies:
   flutter_test:

lib/esc_pos_printer.dart

@@ -11,3 +11,4 @@ export './src/enums.dart';
 export './src/pos_column.dart';
 export './src/pos_styles.dart';
 export './src/printer.dart';
+export './src/printer_bluetooth_manager.dart';

lib/src/printer_bluetooth_manager.dart

+/*
+ * esc_pos_printer
+ * Created by Andrey Ushakov
+ * 
+ * Copyright (c) 2020. All rights reserved.
+ * See LICENSE for distribution and usage details.
+ */
+
+import 'dart:async';
+import 'dart:convert';
+import 'package:rxdart/rxdart.dart';
+// import 'dart:convert';
+// import 'dart:io';
+// import 'dart:typed_data';
+// import 'package:gbk_codec/gbk_codec.dart';
+// import 'package:hex/hex.dart';
+// import 'package:image/image.dart';
+// import 'barcode.dart';
+// import 'commands.dart';
+// import 'enums.dart';
+// import 'pos_column.dart';
+// import 'pos_styles.dart';
+import 'package:flutter_bluetooth_basic/flutter_bluetooth_basic.dart';
+
+/// Bluetooth printer
+class PrinterBluetooth {
+  PrinterBluetooth(this._device);
+  final BluetoothDevice _device;
+  // final BluetoothManager _bluetoothManager = BluetoothManager.instance;
+  final PrinterBluetoothManager _manager = PrinterBluetoothManager();
+  bool _isPrinting = false;
+
+  String get name => _device.name;
+  String get address => _device.address;
+  int get type => _device.type;
+
+  Future _runDelayed(int seconds) {
+    return Future<dynamic>.delayed(Duration(seconds: seconds));
+  }
+
+  void printLine(String text) async {
+    const int timeout = 5;
+    print('============ ${_manager._isScanning}');
+    // if (_bluetoothManager.is) {
+    //   showToast('Print failed (scanning in progress)');
+    //   return;
+    // }
+    if (_isPrinting) {
+      throw Exception('Print failed (another printing in progress)');
+    }
+
+    _isPrinting = true;
+
+    // We have to rescan before connecting, otherwise we can connect only once
+    await _manager._bluetoothManager.startScan(timeout: Duration(seconds: 1));
+    await _manager._bluetoothManager.stopScan();
+
+    // Connect
+    await _manager._bluetoothManager.connect(_device);
+
+    // Subscribe to the events
+    _manager._bluetoothManager.state.listen((state) async {
+      switch (state) {
+        case BluetoothManager.CONNECTED:
+          print('********************* CONNECTED');
+          // to avoid double call
+          // if (!_connected) {
+          if (_device.connected == null || !_device.connected) {
+            print('@@@@SEND DATA......');
+            final List<int> bytes = latin1.encode('test!\n\n\n').toList();
+            await _manager._bluetoothManager.writeData(bytes);
+            // showToast('Data sent'); TODO
+            // return 0;
+          }
+          // TODO sending disconnect signal should be event-based
+          _runDelayed(3).then((dynamic v) async {
+            print('@@@@DISCONNECTING......');
+            await _manager._bluetoothManager.disconnect();
+            _isPrinting = false;
+          });
+          // _connected = true;
+          break;
+        case BluetoothManager.DISCONNECTED:
+          print('********************* DISCONNECTED');
+          // _connected = false;
+          break;
+        default:
+          break;
+      }
+      // return 0;
+    });
+    // Printing timeout
+    _runDelayed(timeout).then((dynamic v) async {
+      if (_isPrinting) {
+        _isPrinting = false;
+        throw Exception('Print failed (timeout)');
+      }
+    });
+  }
+}
+
+/// Bluetooth printer
+/// // TODO rename to BluetoothScanner
+class PrinterBluetoothManager {
+  final BluetoothManager _bluetoothManager = BluetoothManager.instance;
+  // bool _connected = false;
+  bool _isScanning = false;
+  // bool _isPrinting = false;
+  StreamSubscription _scanResultsSubscription;
+  StreamSubscription _isScanningSubscription;
+
+  Stream<bool> get isScanningStream => _bluetoothManager.isScanning;
+
+  BehaviorSubject<List<PrinterBluetooth>> _scanResults =
+      BehaviorSubject.seeded([]);
+  Stream<List<PrinterBluetooth>> get scanResults => _scanResults.stream;
+
+  void startScan(Duration timeout) async {
+    _scanResults.add(<PrinterBluetooth>[]);
+
+    _bluetoothManager.startScan(timeout: Duration(seconds: 4));
+
+    _scanResultsSubscription = _bluetoothManager.scanResults.listen((devices) {
+      _scanResults.add(devices.map((d) => PrinterBluetooth(d)).toList());
+    });
+
+    // TODO move listener to constructor
+    _isScanningSubscription =
+        _bluetoothManager.isScanning.listen((isScanningCurrent) async {
+      // If isScanning value changed (scan just stopped)
+      if (_isScanning && !isScanningCurrent) {
+        _scanResultsSubscription.cancel();
+        _isScanningSubscription.cancel();
+      }
+      _isScanning = isScanningCurrent;
+    });
+  }
+
+  void stopScan() async {
+    await _bluetoothManager.stopScan();
+  }
+}

pubspec.yaml

@@ -13,6 +13,7 @@ dependencies:
   hex: ^0.1.2
   image: ^2.1.4
   gbk_codec: ^0.3.1+3
+  rxdart: ^0.23.1
   flutter_bluetooth_basic:
     git:
       url: git://github.com/andrey-ushakov/flutter_bluetooth_basic