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Description:

bluetooth print

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 : #

add the dependency to your pubspec.yaml file.

dependencies:
flutter:
sdk: flutter
bluetooth_print:
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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
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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>
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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;
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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(),
),
),
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connect #
await bluetoothPrint.connect(_device);
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disconnect #
await bluetoothPrint.disconnect();
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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;
}
});
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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);
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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);
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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'
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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>
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FAQ Support #
you can join this QQ group, feedback your problem

Thanks For #

flutter_blue