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a flutter plugin connect to bluetooth thermal printer support both Android and IOS (eg. Gprinter pt-380、gp-1324、gp-2120)

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thon-ju/bluetooth_print

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pub package

Introduction

BluetoothPrint is a bluetooth plugin for Flutter, a new mobile SDK to help developers build bluetooth thermal printer apps for both iOS and Android.(for example, Gprinter pt-280、pt-380、gp-1324、gp-2120 eg.)

Underway(please suggest)

[ ] print x,y positions
[ ] set paper size
[ ] more print examples

verison

4.0.0(flutter 3.x)
3.0.0(flutter 2.x)
2.0.0(flutter 1.12)
1.2.0(flutter 1.9)

Features

Android iOS Description
scan Starts a scan for Bluetooth Low Energy devices.
connect Establishes a connection to the device.
disconnect Cancels an active or pending connection to the device.
state Stream of state changes for the Bluetooth Device.
print test message print device test message.
print text print custom text, support layout.
print image print image.
print qrcode print qrcode,support change size.
print barcode print barcode

Usage

Example

To use this plugin :

  dependencies:
    flutter:
      sdk: flutter
    bluetooth_print:

Add permissions for Bluetooth

We need to add the permission to use Bluetooth and access location:

Android

In the android/app/src/main/AndroidManifest.xml let’s add:

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

IOS

In the ios/Runner/Info.plist let’s add:

	<dict>  
	    <key>NSBluetoothAlwaysUsageDescription</key>  
	    <string>Need BLE permission</string>  
	    <key>NSBluetoothPeripheralUsageDescription</key>  
	    <string>Need BLE permission</string>  
	    <key>NSLocationAlwaysAndWhenInUseUsageDescription</key>  
	    <string>Need Location permission</string>  
	    <key>NSLocationAlwaysUsageDescription</key>  
	    <string>Need Location permission</string>  
	    <key>NSLocationWhenInUseUsageDescription</key>  
	    <string>Need Location permission</string>

For location permissions on iOS see more at: https://developer.apple.com/documentation/corelocation/requesting_authorization_for_location_services

init a BluetoothPrint instance

import 'package:bluetooth_print/bluetooth_print.dart';
import 'package:bluetooth_print/bluetooth_print_model.dart';


BluetoothPrint bluetoothPrint = BluetoothPrint.instance;

scan

// begin scan
bluetoothPrint.startScan(timeout: Duration(seconds: 4));

// get devices
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(),
    ),
  ),

connect

await bluetoothPrint.connect(_device);

disconnect

await bluetoothPrint.disconnect();

listen state

      bluetoothPrint.state.listen((state) {
      print('cur device status: $state');
# bluetooth_print

      switch (state) {
        case BluetoothPrint.CONNECTED:
          setState(() {
            _connected = true;
          });
          break;
        case BluetoothPrint.DISCONNECTED:
          setState(() {
            _connected = false;
          });
          break;
        default:
          break;
      }
    });

A new flutter plugin project.

print (esc command, receipt mode)

    Map<String, dynamic> config = Map();
    List<LineText> list = List();
    list.add(LineText(type: LineText.TYPE_TEXT, content: 'A Title', weight: 1, align: LineText.ALIGN_CENTER,linefeed: 1));
    list.add(LineText(type: LineText.TYPE_TEXT, content: 'this is conent left', weight: 0, align: LineText.ALIGN_LEFT,linefeed: 1));
    list.add(LineText(type: LineText.TYPE_TEXT, content: 'this is conent right', align: LineText.ALIGN_RIGHT,linefeed: 1));
    list.add(LineText(linefeed: 1));
    list.add(LineText(type: LineText.TYPE_BARCODE, content: 'A12312112', size:10, align: LineText.ALIGN_CENTER, linefeed: 1));
    list.add(LineText(linefeed: 1));
    list.add(LineText(type: LineText.TYPE_QRCODE, content: 'qrcode i', size:10, align: LineText.ALIGN_CENTER, linefeed: 1));
    list.add(LineText(linefeed: 1));
## Getting Started

    ByteData data = await rootBundle.load("assets/images/guide3.png");
    List<int> imageBytes = data.buffer.asUint8List(data.offsetInBytes, data.lengthInBytes);
    String base64Image = base64Encode(imageBytes);
    list.add(LineText(type: LineText.TYPE_IMAGE, content: base64Image, align: LineText.ALIGN_CENTER, linefeed: 1));
This project is a starting point for a Flutter
[plug-in package](https://flutter.dev/developing-packages/),
a specialized package that includes platform-specific implementation code for
Android and/or iOS.

    await bluetoothPrint.printReceipt(config, list);

For help getting started with Flutter, view our online documentation, which offers tutorials, samples, guidance on mobile development, and a full API reference.

print (tsc command, label mode)

    Map<String, dynamic> config = Map();
    config['width'] = 40; // 标签宽度,单位mm
    config['height'] = 70; // 标签高度,单位mm
    config['gap'] = 2; // 标签间隔,单位mm

    // x、y坐标位置,单位dpi,1mm=8dpi
    List<LineText> list = List();
    list.add(LineText(type: LineText.TYPE_TEXT, x:10, y:10, content: 'A Title'));
    list.add(LineText(type: LineText.TYPE_TEXT, x:10, y:40, content: 'this is content'));
    list.add(LineText(type: LineText.TYPE_QRCODE, x:10, y:70, content: 'qrcode i\n'));
    list.add(LineText(type: LineText.TYPE_BARCODE, x:10, y:190, content: 'qrcode i\n'));

    List<LineText> list1 = List();
    ByteData data = await rootBundle.load("assets/images/guide3.png");
    List<int> imageBytes = data.buffer.asUint8List(data.offsetInBytes, data.lengthInBytes);
    String base64Image = base64Encode(imageBytes);
    list1.add(LineText(type: LineText.TYPE_IMAGE, x:10, y:10, content: base64Image,));

    await bluetoothPrint.printLabel(config, list);
    await bluetoothPrint.printLabel(config, list1);

Troubleshooting

ios import third party library

[Please Read link: https://stackoverflow.com/questions/19189463/cocoapods-podspec-issue)
*.podspec add:

# .a filename must begin with lib, eg. 'libXXX.a'
s.vendored_libraries = '**/*.a'

error:'State restoration of CBCentralManager is only allowed for applications that have specified the "bluetooth-central" background mode'

info.plist add:

<key>NSBluetoothAlwaysUsageDescription</key>
<string>Allow App use bluetooth?</string>
<key>NSBluetoothPeripheralUsageDescription</key>
<string>Allow App use bluetooth?</string>
<key>UIBackgroundModes</key>
<array>
    <string>bluetooth-central</string>
    <string>bluetooth-peripheral</string>
</array>

FAQ Support

you can join this QQ group, feedback your problem

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a flutter plugin connect to bluetooth thermal printer support both Android and IOS (eg. Gprinter pt-380、gp-1324、gp-2120)

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