bluetooth_print_plus 1.1.3

BluetoothPrint is a bluetooth plugin to help developers build bluetooth thermal printer apps for both iOS and Android..

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.)

verison

1.x.x -> blue and tsc command

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.

Tsc Command

	Android	iOS	Description
size	✅	✅	Set label size in millimeters
selfTest	✅	✅	Print self inspection page information
print	✅	✅	Print out data stored in the buffer
gap	✅	✅	Define the vertical spacing distance between two label papers.
speed	✅	✅	Set printing speed
density	✅	✅	Set printing concentration
cls	✅	✅	Clear data from image buffer
text	✅	✅	print string
image	✅	✅	print image
barCode	✅	✅	This instruction is used to draw one-dimensional barcodes
qrCode	✅	✅	This instruction is used to print QR codes
bar	✅	✅	This instruction is used to draw lines on labels
box	✅	✅	This instruction is used to draw a rectangular box on a label

Usage

Example

To use this plugin :

• add the dependency to your pubspec.yaml file.

  dependencies:
    flutter:
      sdk: flutter
    bluetooth_print_plus:

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


final _bluetoothPrintPlus = BluetoothPrintPlus.instance;

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: [
              Expanded(
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Text(d.name ?? ''),
                      Text(
                        d.address ?? 'null',
                        overflow: TextOverflow.ellipsis,
                        style: const TextStyle(
                            fontSize: 12,
                            color: Colors.grey
                        ),
                      ),
                      const Divider(),
                    ],
                  )
              ),
              const SizedBox(width: 10,),
              ElevatedButton(
                  onPressed: () async {
                      _bluetoothPrintPlus.stopScan();
                      _bluetoothPrintPlus.connect(d);
                      _device = d;
                  },
                  child: const Text("connect"),
              )
            ],
          ),
    )).toList(),
  ),
)

connect

await _bluetoothPrintPlus.connect(_device);

disconnect

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

listen state

_bluetoothPrintPlus.state.listen((state) {
  print('cur device status: $state');
  switch (state) {
    case BluetoothPrint.CONNECTED:
      setState(() {
        _connected = true;
      });
      break;
    case BluetoothPrint.DISCONNECTED:
      setState(() {
        _connected = false;
      });
      break;
    default:
      break;
  }
});

print (tsc command, label mode)

    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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Thanks For

• flutter_blue