flutter_niimbot #

An unofficial Flutter package for building label-printing experiences with NIIMBOT Bluetooth printers.

Current device support: NIIMBOT D11H only.

Support for other NIIMBOT models is not available yet.

This package is under active development. The label model, renderer, and D11H application facade are available through the stable public entry point.

Features #

• Define label dimensions in millimeters
• Render text to a monochrome raster at 203 DPI
• Use normal or 90-degree rotated label orientation
• Configure text alignment, position, wrapping, size, and weight
• Work with typed BLE device, connection, service, and failure models
• Scan, connect, and print through the D11H application facade
• Warm-connection printing on iOS (no pre-print GATT refresh)
• Probe-aligned print characteristic discovery for real devices

Supported printers #

No other NIIMBOT printer model is currently supported or tested.

Installation #

Add flutter_niimbot to your app:

dependencies:
  flutter_niimbot: ^0.1.0-dev.9

Then fetch the dependency:

flutter pub get

Usage #

Import the stable public entry point:

import 'package:flutter_niimbot/niimbot.dart';

Create and render a text label:

final document = LabelDocument(
  size: LabelSize.d11h12x22,
  orientation: LabelOrientation.rotated90,
  elements: [
    LabelText(
      text: '상품명\n닉네임',
      xMm: 0,
      yMm: 1,
      widthMm: 22,
      heightMm: 10,
      fontSizePt: 15,
      alignment: LabelTextAlignment.start,
      horizontalPosition: LabelHorizontalPosition.center,
      wrap: true,
      bold: true,
    ),
  ],
);

final raster = await const TextLabelRenderer().render(document);

Print through the high-level facade:

final printer = D11hPrinter();

try {
  final devices = await printer.scan();
  if (devices.isEmpty) {
    throw StateError('No BLE printers found.');
  }

  await printer.connect(devices.first.deviceId);
  await printer.printLabel(document);
  // Or render first, then print on the warm connection:
  // await printer.printRenderedLabel(raster);
} finally {
  await printer.dispose();
}

Printing behavior #

• connect() discovers services, negotiates MTU, subscribes to the print characteristic, and settles briefly before the link is used.
• printLabel() and printRenderedLabel() print on the current BLE connection. They do not disconnect and reconnect before each label.
• printRenderedLabel() matches the working tool/d11h_probe path: render first, then call printRaster with a 30 ms inter-write delay.
• All printer operations are serialized through an internal queue.
• scan() disconnects an active printer before discovery and ends with an explicit stopScan() so iOS scan results are not lost to timeout cleanup.

Print characteristic discovery #

findD11hPrintCharacteristic() prefers FFF0/FFF1, then falls back to any characteristic that supports notify and writeWithoutResponse, matching the probe app's discovery logic on iOS.

Bluetooth setup #

Applications using BLE functionality must configure the Android and iOS Bluetooth permissions required by flutter_reactive_ble. Permission prompts remain the responsibility of the application.

On iOS, avoid requesting Bluetooth permission through permission_handler before scanning; let Core Bluetooth handle the system prompt.

The repository includes an internal D11H probe application under tool/d11h_probe for protocol research and diagnostics.

API status #

Use package:flutter_niimbot/niimbot.dart for the public API.

D11hPrinter, D11H characteristic discovery, label models, rendering, and BLE transport types are exported by the stable entry point.

package:flutter_niimbot/niimbot_research.dart exposes low-level probe and protocol research APIs. These APIs may change without notice and are not covered by semantic-versioning guarantees.

Limitations #

• Only NIIMBOT D11H has been characterized and tested.
• Text labels are supported; image, barcode, and QR-code elements are not yet part of the public renderer.
• A successful BLE write alone does not guarantee that a physical label was printed.

Disclaimer #

This is an independent, unofficial project. It is not affiliated with, endorsed by, or sponsored by NIIMBOT.

License #

See LICENSE.