blovedream_printer 0.1.1

Flutter plugin for Blovedream (BLD) Android terminals with a built-in thermal / label printer. Wraps the OEM android.bld.PrintManager service via reflection.

blovedream_printer

Flutter plugin for Blovedream (BLD) Android terminals (PDAs, POS handhelds) with a built-in thermal / label printer. Wraps the OEM android.bld.PrintManager service through Java reflection — no proprietary jar to embed.

⚠️ Works only on devices that ship the Blovedream printer service. The system property ro.blovedream_support_print must be exposed by the firmware. On any other Android device, open() throws a PlatformException(BLD_ERROR, ...).

Features

• Open / close / start / reset the printer
• Print text (alignment, font size, bold, underline)
• Print 1D barcodes: UPC-A/E, EAN-8/13, CODE39, CODE93, CODE128, ITF, CODABAR — with HRI position
• Print QR codes (alignment, size)
• Print bitmaps from a file path or raw bytes (Uint8List)
• Line feed (n lines)
• Label-paper mode (black-mark detection, feed-to-next-mark)
• Configure: density, font size, line spacing, reverse, underline
• Read the firmware version
• Stream of print events (onPrintCallback, onVersion)

Platform support

Platform	Status
Android	✅ supported (Blovedream firmware required)
iOS / web / desktop	❌ not applicable (hardware-bound)

Installation

dependencies:
  blovedream_printer: ^0.1.1

flutter pub get

Permissions

The plugin itself does not require any Android permission — the BLD print service is a system service the OEM exposes to all apps, and bitmap data is either passed in-memory (Uint8List) or via a file path the consumer app already has access to.

If your app passes file paths from the gallery (e.g. via image_picker), add the relevant media-read permissions to your own AndroidManifest.xml:

<uses-permission
    android:name="android.permission.READ_EXTERNAL_STORAGE"
    android:maxSdkVersion="32"/>
<uses-permission android:name="android.permission.READ_MEDIA_IMAGES"/>
<uses-permission android:name="android.permission.READ_MEDIA_VISUAL_USER_SELECTED"/>

Usage

Quick start

import 'package:blovedream_printer/blovedream_printer.dart';

final printer = BlovedreamPrinter.instance;

// Listen to print results & firmware version.
printer.events.listen((event) {
  if (event is PrintCallbackEvent) {
    debugPrint('print result: ${event.errorCode}');
  } else if (event is PrinterVersionEvent) {
    debugPrint('firmware: ${event.version}');
  }
});

await printer.open();
await printer.setFontSize(FontSize.middle);

await printer.printText('Hello Blovedream!', align: PrintAlign.center);
await printer.printQr('https://example.com');
await printer.lineFeed(3);

await printer.start();   // commits the queued commands

Label paper (black-mark detection)

// Configure once at boot:
await printer.setUnwindPaperLen(30);   // 3 mm
await printer.setBlackLabel(true);

// For each label:
await printer.lineFeed(2);
await printer.printText(
  'Order #12345',
  align: PrintAlign.center,
  fontSize: FontSize.large,
  bold: true,
);
await printer.printBarcode(
  'AB-12345',
  type: BarCodeType.code128,
  hri: HriPosition.below,
);
await printer.goToNextMark(feedSpace: 1000);   // feeds to next black mark

Image printing

// From a file path (e.g. the gallery)
await printer.printBitmapPath('/path/to/image.png', align: PrintAlign.center);
await printer.start();

// From raw bytes (PNG/JPEG)
final Uint8List bytes = await rootBundle
    .load('assets/logo.png')
    .then((b) => b.buffer.asUint8List());
await printer.printBitmapBytes(bytes);
await printer.start();

Error codes

PrintCallbackEvent.errorCode is a PrinterErrorCode enum. The most common values:

Code	Meaning
noError	Success
printNoPaper	Out of paper
printHot	Print head overheated
devNoBattery	Battery too low
devNotOpen	open() was not called or has failed
dataInvalid	Malformed command

The full list is in lib/src/enums.dart.

How it works

The Blovedream firmware exposes a system service whose AIDL is android.bld.PrintManager. That class is not part of the AOSP SDK, so we can't link it at compile time on a regular machine. Instead, the Android side of this plugin resolves every method via java.lang.reflect.Method at runtime and proxies the listener interface (android.bld.print.aidl.PrinterBinderListener) with java.lang.reflect.Proxy. This means:

• The plugin compiles on any machine, no proprietary jar needed.
• On a non-Blovedream device, open() fails fast with a clear error.

Example

A complete example covering text, barcode, QR, image, and label-mode workflows is available in the example/ folder of the repository.

Contributing

Issues and pull requests are welcome on GitHub.

License

MIT — see LICENSE.