Introduction

Bluetooth Print Plus is a Bluetooth plugin used to print thermal printers in Flutter, a new mobile SDK to help developers build bluetooth thermal printer apps for iOS and Android.

Important, important, important. First, you need to run the demo to confirm the printer command type ! ! ! now support tspl/tsc、cpcl、esc pos. If this plugin is helpful to you, please give it a like, Thanks.

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Plan

Version	plan
1.1.x	blue and tsc command, esc print image command
1.5.x	support cpcl command
2.x.x	improve esc command
3.x.x	support zpl command

Features

	Android	iOS	Description
scan	:white_check_mark:	:white_check_mark:	Starts a scan for Bluetooth Low Energy devices.
connect	:white_check_mark:	:white_check_mark:	Establishes a connection to the device.
disconnect	:white_check_mark:	:white_check_mark:	Cancels an active or pending connection to the device.
state	:white_check_mark:	:white_check_mark:	Stream of state changes for the Bluetooth Device.

Usage

Example

To use this plugin :

• add the dependency to your pubspec.yaml file.

dependencies:
  flutter:
    sdk: flutter
  bluetooth_print_plus: ^2.3.4

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_FINE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>

IOS

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

<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_plus/bluetooth_print_plus.dart';

final _bluetoothPrintPlus = BluetoothPrintPlus.instance;

listen

• state

_bluetoothPrintPlus.state.listen((state) {
  print('********** state change: $state **********');
  switch(state) {
    case BPPState.blueOn:
      /// blueOn, do something
      break;
    case BPPState.blueOff:
      /// blueOff, do something
      break;
    case BPPState.deviceConnected:
      /// deviceConnected, do something
      break;
    case BPPState.deviceDisconnected:
      /// deviceDisconnected, do something
      break;
  }
});

• received Data

_bluetoothPrintPlus.receivedData.listen((data) {
  print('********** received data: $data **********');
  /// received data, do something...
});

scan

// begin scan
_bluetoothPrintPlus.startScan(timeout: const Duration(seconds: 30));

// get devices
StreamBuilder<List<BluetoothDevice>>(
  stream: _bluetoothPrintPlus.scanResults,
  initialData: [],
  builder: (c, snapshot) => ListView(
    children: snapshot.data!.map((d) => Container(
      padding: const EdgeInsets.only(left: 10, right: 10, bottom: 5),
      child: Row(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: [ .... ],
          ),
    )).toList(),
  ),
)

connect

await _bluetoothPrintPlus.connect(_device);

disconnect

await _bluetoothPrintPlus.disconnect();
or
await  BluetoothPrintPlus.instance.disconnect();

print/write

/// for example: write tsc command
final ByteData bytes = await rootBundle.load("assets/dithered-image.png");
final Uint8List image = bytes.buffer.asUint8List();
await tscCommand.cleanCommand();
await tscCommand.cls();
await tscCommand.size(width: 76, height: 130);
await tscCommand.image(image: image, x: 50, y: 60);
await tscCommand.print(1);
final cmd = await tscCommand.getCommand();
if (cmd == null) return;
BluetoothPrintPlus.instance.write(cmd);

Troubleshooting

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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