esc_pos_utils

Base Flutter/Dart classes for ESC/POS printing. Generator class generates ESC/POS commands that can be sent to a thermal printer.

This is the “base” library that used for:

Flutter WiFi/Ethernet printing: esc_pos_printer
Flutter Bluetooth printing: esc_pos_bluetooth

Main Features

Connect to Wi-Fi / Ethernet printers
Simple text printing using text method
Tables printing using row method
Text styling:
- size, align, bold, reverse, underline, different fonts, turn 90°
Print images
Print barcodes
- UPC-A, UPC-E, JAN13 (EAN13), JAN8 (EAN8), CODE39, ITF (Interleaved 2 of 5), CODABAR (NW-7), CODE128
Paper cut (partial, full)
Beeping (with different duration)
Paper feed, reverse feed

Note: Your printer may not support some of the presented features (some styles, partial/full paper cutting, reverse feed, barcodes…).

Generate a Ticket

Simple ticket with styles:

List<int> testTicket() {
  final List<int> bytes = [];
  // Using default profile
  final profile = await CapabilityProfile.load();
  final generator = Generator(PaperSize.mm80, profile);
  List<int> bytes = [];

  bytes += generator.text(
      'Regular: aA bB cC dD eE fF gG hH iI jJ kK lL mM nN oO pP qQ rR sS tT uU vV wW xX yY zZ');
  bytes += generator.text('Special 1: àÀ èÈ éÉ ûÛ üÜ çÇ ôÔ',
      styles: PosStyles(codeTable: PosCodeTable.westEur));
  bytes += generator.text('Special 2: blåbærgrød',
      styles: PosStyles(codeTable: PosCodeTable.westEur));

  bytes += generator.text('Bold text', styles: PosStyles(bold: true));
  bytes += generator.text('Reverse text', styles: PosStyles(reverse: true));
  bytes += generator.text('Underlined text',
      styles: PosStyles(underline: true), linesAfter: 1);
  bytes += generator.text('Align left', styles: PosStyles(align: PosAlign.left));
  bytes += generator.text('Align center', styles: PosStyles(align: PosAlign.center));
  bytes += generator.text('Align right',
      styles: PosStyles(align: PosAlign.right), linesAfter: 1);

  bytes += generator.text('Text size 200%',
      styles: PosStyles(
        height: PosTextSize.size2,
        width: PosTextSize.size2,
      ));

  bytes += generator.feed(2);
  bytes += generator.cut();
  return bytes;
}

Print a table row:

generator.row([
    PosColumn(
      text: 'col3',
      width: 3,
      styles: PosStyles(align: PosAlign.center, underline: true),
    ),
    PosColumn(
      text: 'col6',
      width: 6,
      styles: PosStyles(align: PosAlign.center, underline: true),
    ),
    PosColumn(
      text: 'col3',
      width: 3,
      styles: PosStyles(align: PosAlign.center, underline: true),
    ),
  ]);

Print an image:

This package implements 3 ESC/POS functions:

ESC * – print in column format
GS v 0 – print in bit raster format (obsolete)
GS ( L – print in bit raster format

Note that your printer may support only some of the above functions.

import 'dart:io';
import 'package:image/image.dart';

final ByteData data = await rootBundle.load('assets/logo.png');
final Uint8List bytes = data.buffer.asUint8List();
final Image image = decodeImage(bytes);
// Using `ESC *`
generator.image(image);
// Using `GS v 0` (obsolete)
generator.imageRaster(image);
// Using `GS ( L`
generator.imageRaster(image, imageFn: PosImageFn.graphics);

Print a Barcode:

final List<int> barData = [1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 4];
generator.barcode(Barcode.upcA(barData));

Print a QR Code:

Using native ESC/POS commands:

generator.qrcode('example.com');

To print a QR Code as an image (if your printer doesn’t support native commands), add qr_flutter and path_provider as a dependency in your pubspec.yaml file.

String qrData = "google.com";
const double qrSize = 200;
try {
  final uiImg = await QrPainter(
    data: qrData,
    version: QrVersions.auto,
    gapless: false,
  ).toImageData(qrSize);
  final dir = await getTemporaryDirectory();
  final pathName = '${dir.path}/qr_tmp.png';
  final qrFile = File(pathName);
  final imgFile = await qrFile.writeAsBytes(uiImg.buffer.asUint8List());
  final img = decodeImage(imgFile.readAsBytesSync());

  generator.image(img);
} catch (e) {
  print(e);
}

Using Code Tables

Different printers support different sets of code tables. Some printer models are defined in CapabilityProfile class. So, if you want to change the default code table, it’s important to choose the right profile:

// Xprinter XP-N160I
final profile = await CapabilityProfile.load('XP-N160I');
final generator = Generator(PaperSize.mm80, profile);
bytes += generator.setGlobalCodeTable('CP1252');

All available profiles can be retrieved by calling :

final profiles = await CapabilityProfile.getAvailableProfiles();

How to Help

Add a CapabilityProfile to support your printer’s model. A new profile should be added to lib/resources/capabilities.json file
Test your printer and add it in the table: Wifi/Network printer or Bluetooth printer
Test and report bugs
Share your ideas about what could be improved (code optimization, new features…)