I. Introduction:
- I guess flutter is no stranger to everyone, so I won’t recommend it anymore
- Please allow me to go straight to the topic =))
II. Printer:
This is a picture of my printer, it’s a thermal printer
III. Flutter:
- To use this bluetooth printer I use the bluetooth_print library
- Here is the code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 | import 'package:bluetooth_print/bluetooth_print.dart'; import 'package:bluetooth_print/bluetooth_print_model.dart'; import 'package:flutter/material.dart'; void main() { runApp(MyApp()); } class MyApp extends StatelessWidget { @override Widget build(BuildContext context) { return MaterialApp( title: 'Flutter Demo', theme: ThemeData( primarySwatch: Colors.blue, visualDensity: VisualDensity.adaptivePlatformDensity, ), home: MyHomePage(), ); } } class MyHomePage extends StatefulWidget { @override _MyHomePageState createState() => _MyHomePageState(); } class _MyHomePageState extends State<MyHomePage> { BluetoothPrint bluetoothPrint = BluetoothPrint.instance; bool _connected = false; BluetoothDevice _device; String tips = 'Không có thiết bị được kết nối'; @override void initState() { super.initState(); if (_connected) tips = 'Đã kết nối'; // Khi vào trang sẽ check xem đã kết nối trước đó hay chưa WidgetsBinding.instance.addPostFrameCallback((_) => initBluetooth()); } Future<void> initBluetooth() async { bluetoothPrint.startScan(timeout: Duration(seconds: 4)); // scan trong 4s, tìm device bool isConnected = await bluetoothPrint.isConnected; bluetoothPrint.state.listen((state) { print('cur device status: $state'); switch (state) { case BluetoothPrint.CONNECTED: setState(() { _connected = true; tips = 'Kết nối thành công'; }); break; case BluetoothPrint.DISCONNECTED: setState(() { _connected = false; tips = 'Ngắt kết nối thành công'; }); break; default: break; } }); if (!mounted) return; // nếu chưa kết nối thì không làm gì if (isConnected) { setState(() { _connected = true; }); } } void _onConnect() async { // chỗ này đọc lệnh chắc mọi người cũng hiểu được :v if (_device != null && _device.address != null) { await bluetoothPrint.connect(_device); } else { setState(() { tips = 'Vui lòng chọn thiết bị'; }); print('please select device'); } } void _onDisconnect() async { await bluetoothPrint.disconnect(); } void _sendData() async { Map<String, dynamic> config = Map(); List<LineText> list = List(); list.add(LineText( type: LineText.TYPE_TEXT, content: 'MAY IN EXAMPLE', weight: 1, align: LineText.ALIGN_CENTER, linefeed: 1)); list.add(LineText( type: LineText.TYPE_TEXT, content: 'Dia chi: Da Nang', weight: 0, align: LineText.ALIGN_CENTER, linefeed: 1)); list.add(LineText(linefeed: 1)); list.add(LineText( type: LineText.TYPE_TEXT, content: 'HOA DON', align: LineText.ALIGN_CENTER, weight: 1, linefeed: 1)); final DateTime now = DateTime.now(); list.add(LineText( type: LineText.TYPE_TEXT, content: 'Ngay in: ' + now.toString(), align: LineText.ALIGN_LEFT, linefeed: 1)); list.add(LineText(linefeed: 1)); list.add(LineText(type: LineText.TYPE_TEXT, content: 'In cho vui')); await bluetoothPrint.printReceipt(config, list); } @override Widget build(BuildContext context) { return MaterialApp( home: Scaffold( appBar: AppBar(title: const Text('Máy in')), body: RefreshIndicator( onRefresh: () => bluetoothPrint.startScan(timeout: Duration(seconds: 4)), child: SingleChildScrollView( child: Column( children: <Widget>[ Row( mainAxisAlignment: MainAxisAlignment.center, children: <Widget>[ Padding( padding: EdgeInsets.symmetric(vertical: 10, horizontal: 10), child: Text(tips), ), ], ), Divider(), StreamBuilder<List<BluetoothDevice>>( stream: bluetoothPrint.scanResults, initialData: [], builder: (c, snapshot) => Column( children: snapshot.data .map((d) => ListTile( title: Text(d.name ?? ''), subtitle: Text(d.address), onTap: () async { setState(() { _device = d; }); }, trailing: _device != null && _device.address == d.address ? Icon( Icons.check, color: Colors.green, ) : null, )) .toList(), ), ), Divider(), Container( padding: EdgeInsets.fromLTRB(20, 5, 20, 10), child: Column( children: <Widget>[ Row( mainAxisAlignment: MainAxisAlignment.center, children: <Widget>[ OutlineButton( child: Text('Kết nối'), onPressed: _connected ? null : _onConnect, ), SizedBox(width: 10.0), OutlineButton( child: Text('Ngắt kết nối'), onPressed: _connected ? _onDisconnect : null, ), ], ), OutlineButton( child: Text('In hóa đơn'), onPressed: _connected ? _sendData : null, ), ], ), ) ], ), ), ), // phần dưới là button scan để tìm kiếm device floatingActionButton: StreamBuilder<bool>( stream: bluetoothPrint.isScanning, initialData: false, builder: (c, snapshot) { if (snapshot.data) { return FloatingActionButton( child: Icon(Icons.stop), onPressed: () => bluetoothPrint.stopScan(), backgroundColor: Colors.red, ); } else { return FloatingActionButton( child: Icon(Icons.search), onPressed: () => bluetoothPrint.startScan(timeout: Duration(seconds: 4))); } }, ), ), ); } } |
- When running build you will get 1 error code as follows
- This is an android error code that requires its sdk to at least version 21, while currently it is version 16
- Here, you go to the file
build.gradlein the following path:android/app/build.gradle - Find the
defaultConfig, editminSdkVersionto 21
- Run as usual, but maybe later it will improve the version so please read the error carefully to see which version it needs
- This code is pretty clear so I don’t have much to explain, so stop showing the interface and images when printing for everyone to see.
- Interface on the virtual machine
- Invoice when printing
IV. Conclusion
- The disadvantage of thermal printers is that there will be machines that support Vietnamese and not
- Unfortunately my device is not supporting
- I have searched many sites online but none of them have been successful
- But in the difficulty is the near wisdom
- It is converting these typefaces into images and then printing the images: v
- I don’t know if it will work or not because these days are too busy so I haven’t tried it yet, I don’t know if any of you have tried it, if you give me some experience
- Well, and you can see your article considered example is okay, that’s right: v
- Because I wrote this article only to shorten what is easy to see before digging into it
- The pain when a beginner learns something like me is to find an example but there is so much inside, and sometimes it even causes an error, I have to find a fix to @@, and read don’t understand anything in, bored: v
- Hopefully my next article will share with everyone how to print Vietnamese in pictures: v