posprinter_usb_android

Android USB host transport for ESC/POS thermal receipt printers.

It lists the printers attached over USB, performs the Android USB permission handshake, opens the bulk OUT endpoint and writes raw ESC/POS bytes to it. There is no Bluetooth, BLE or network (TCP) code in this package, and no third-party Dart dependency: it only depends on Flutter.

This package is a maintained, Android-only fork of flutter_pos_printer_platform_image_3 1.2.4. See CHANGELOG.md for what changed and LICENSE for attribution.

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Platform support

	Android	iOS	Windows	macOS	Linux	Web
USB host printing	✅	—	—	—	—	—

Android exposes USB host access through UsbManager, which this plugin drives. On every other platform the API is a no-op: discovery() yields nothing, connect() returns false and the state stream is empty.

Requirements

• Android minSdk 21 or newer.
• android.hardware.usb.host on the device (declared as required="false" by the plugin, so the app still installs on devices without a USB host port).
• Flutter 3.44 / Dart 3.12 or newer. This is what lets the module use AGP's built-in Kotlin support instead of applying the Kotlin Gradle Plugin itself.

Usage

import 'package:posprinter_usb_android/posprinter_usb_android.dart';

final PrinterManager manager = PrinterManager.instance;

// 1. List attached printers.
final List<PrinterDevice> printers = await manager
    .discovery(type: PrinterType.usb)
    .toList();

// 2. Connect. Completes only after the Android permission dialog is answered.
final PrinterDevice printer = printers.first;
final bool connected = await manager.connect(
  type: PrinterType.usb,
  model: UsbPrinterInput(
    name: printer.name,
    vendorId: printer.vendorId,
    productId: printer.productId,
  ),
);

// 3. Send raw ESC/POS bytes.
await manager.send(type: PrinterType.usb, bytes: escPosBytes);

// 4. Close.
await manager.disconnect(type: PrinterType.usb);

USB state events

PrinterManager.instance.stateUSB reports what the platform is doing:

USBStatus	Meaning
none	No printer connected (also sent on detach).
connecting	Android is showing the USB permission dialog.
connected	Access was granted.
attached	A USB device was just plugged in — a good moment to reconnect.

manager.stateUSB.listen((USBStatus status) {
  if (status == USBStatus.attached) {
    // The printer was replugged; try to reconnect it.
  }
});

ESC/POS bytes

The plugin only transports bytes. Generate them with flutter_esc_pos_utils or any other ESC/POS generator.

Example

example/ contains a small app that scans for USB printers, connects to the one you tap and prints a test receipt. Run it on a physical Android device with a USB receipt printer attached:

cd example
flutter run

Credits

Forked from flutter_pos_printer_platform_image_3 by diantahoc, which in turn was forked from flutter_pos_printer_platform by arthas1888.

License

MIT — see LICENSE. The upstream copyright notice is retained.