thermal_printer

Description:

thermal printer

thermal_printer #

A library to discover printers, and send printer commands.
This library allows to print esc commands to printers in different platforms such as android, ios, windows and different interfaces as Bluetooth and BLE, USB and Wifi/Ethernet
Inspired by flutter_pos_printer.
Main Features #

Android, iOS and Windows support
Scan for bluetooth devices
Send raw List<int> bytes data to a device, review this library to generate ESC/POS commands flutter_esc_pos_utils.

Features #




Android
iOS
Windows
Description




USB interface
✅
🔳
✅
Allows connection with usb devices.


Bluetooth classic interface
✅
🔳
🔳
Allows connection with classic bt devices.


Bluetooth low energy (BLE) interface
✅
✅
🔳
Allows connection with bt BLE devices.


Net (ethernet/wifi) interface
✅
✅
✅
Allows connection with network devices.


scan
✅
✅
✅
Starts a scan for only Bluetooth devices or network devices(Android/iOS).


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
✅
✅
✅
print bytes.



Getting Started #
For a full example please check /example folder. Here are only the most important parts of the code to illustrate how to use the library.
Generate bytes to print through flutter_esc_pos_utils.
import 'package:esc_pos_utils/esc_pos_utils.dart';

final profile = await CapabilityProfile.load();
final generator = Generator(PaperSize.mm58, profile);
List<int> bytes = [];

bytes += generator.text('Test Print', styles: const PosStyles(align: PosAlign.center));
bytes += generator.text('Product 1');
bytes += generator.text('Product 2');
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Android #
Allow to connect bluetooth (classic and BLE), USB and network devices
Change the minSdkVersion for Android #
thermal_printer is compatible only from version 21 of Android SDK so you should change this in android/app/build.gradle:
In build.gradle set
defaultConfig {
...
minSdkVersion 19
targetSdkVersion 33
...
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select type of device PrinterType ( bluetooth, usb, network)
if select bluetooth you can send optional params

isBle -> allow to connect with bluetooth that supports this technology
autoconnect -> allow to reconnect when state of device is None

USB: you can enable the native broadcast receiver to notify connected usb devices
put the following code in AndroidManifest
<receiver
android:name="com.codingdevs.thermal_printer.usb.UsbReceiver"
android:exported="false">

<intent-filter>
<action android:name="android.hardware.usb.action.ACTION_USB_PERMISSION" />
<action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />

</intent-filter>
</receiver>
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iOS #
Allow to connect bluetooth (BLE) and network devices
Windows #
Allow to connect USB and network devices
To network devices is necessary to set ipAddress
How to use it #
init a PrinterManager instance #
import 'package:thermal_printer/thermal_printer.dart';

var printerManager = PrinterManager.instance;

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scan #
var devices = [];
_scan(PrinterType type, {bool isBle = false}) {
// Find printers
PrinterManager.instance.discovery(type: type, isBle: isBle).listen((device) {
devices.add(device);
});
}
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connect #
_connectDevice(PrinterDevice selectedPrinter, PrinterType type, {bool reconnect = false, bool isBle = false, String? ipAddress = null}) async {
switch (type) {
// only windows and android
case PrinterType.usb:
await PrinterManager.instance.connect(
type: type,
model: UsbPrinterInput(name: selectedPrinter.name, productId: selectedPrinter.productId, vendorId: selectedPrinter.vendorId));
break;
// only iOS and android
case PrinterType.bluetooth:
await PrinterManager.instance.connect(
type: type,
model: BluetoothPrinterInput(
name: selectedPrinter.name,
address: selectedPrinter.address!,
isBle: isBle,
autoConnect: reconnect));
break;
case PrinterType.network:
await PrinterManager.instance.connect(type: type, model: TcpPrinterInput(ipAddress: ipAddress ?? selectedPrinter.address!));
break;
default:
}
}
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disconnect #
_disconnectDevice(PrinterType type) async {
await PrinterManager.instance.disconnect(type: type);
}
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listen bluetooth state #
PrinterManager.instance.stateBluetooth.listen((status) {
log(' ----------------- status bt $status ------------------ ');
});
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send bytes to print #
_sendBytesToPrint(List<int> bytes, PrinterType type) async {
PrinterManager.instance.send(type: type, bytes: bytes);
}

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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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Credits #

https://github.com/andrey-ushakov/esc_pos_utils
https://github.com/bailabs/esc-pos-printer-flutter
https://github.com/feedmepos/flutter_printer/tree/master/packages/flutter_pos_printer