esc_pos_gen

Description:

esc pos gen

esc_pos_gen #

Declarative-style ESC/POS commands for printing.
Generator class generates printing properties such as
CapabilityProfile, PaperSize, etc.
PosComponent classes generates bytes for printing ESC/POS commands.
Combine both to create a Paper object that can generate all commands from PosComponents to bytes.
Features #

📝 Declarative-style (just like creating widgets)
📰 Tables printing using PosRow
😎 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 Paper #
Simple paper with styles: #
List<int> generatePaper() {
final CapabilityProfile profile = await CapabilityProfile.load();
final Generator generator = Generator(
PaperSize.mm58,
profile,
);

final List<PosComponent> components = <PosComponent>[
const PosText.center('My Store'),
const PosSeparator(),
PosList.builder(
count: 20,
builder: (int i) {
return PosList(
<PosComponent>[
PosRow.leftRightText(
leftText: 'Product $i',
rightText: 'US\$ $i',
),
PosRow.leftRightText(
leftText: '1 x US\$ $i',
leftTextStyles: const PosStyles.defaults(
fontType: PosFontType.fontB,
),
rightText: 'US\$ $i',
rightTextStyles: const PosStyles.defaults(
align: PosAlign.right,
fontType: PosFontType.fontB,
),
),
],
);
},
),
const PosSeparator(),
PosBarcode.code128('{A12345'.split('')),
const PosSeparator(),
const PosFeed(1),
const PosCut(),
];

final Paper paper = Paper(
generator: generator,
components: components,
);

return paper.bytes;
}
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Simple paper with a component delegate: #
class StoreSocialMediaLinks extends PosDelegate {
const StoreSocialMediaLinks();

PosComponent build(Generator generator) {
return PosList(<PosComponent>[
PosRow.leftRightText(
leftText: 'Instagram',
leftTextStyles: const PosStyles.defaults(
fontType: PosFontType.fontB,
),
rightText: '@iandi.s',
rightTextStyles: const PosStyles.defaults(
align: PosAlign.right,
fontType: PosFontType.fontB,
),
),
PosRow.leftRightText(
leftText: 'Github',
leftTextStyles: const PosStyles.defaults(
fontType: PosFontType.fontB,
),
rightText: 'github.com/iandis',
rightTextStyles: const PosStyles.defaults(
align: PosAlign.right,
fontType: PosFontType.fontB,
),
),
]);
}
}

List<int> generatePaper() {
final CapabilityProfile profile = await CapabilityProfile.load();
final Generator generator = Generator(
PaperSize.mm58,
profile,
);

final List<PosComponent> components = <PosComponent>[
const PosText.center('My Social Media Links'),
const PosSeparator(),
const PosComponent.delegate(StoreSocialMediaLinks()),
const PosSeparator(),
const PosFeed(1),
const PosCut(),
];

final Paper paper = Paper(
generator: generator,
components: components,
);

return paper.bytes;
}
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Print a table row: #
PosRow([
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,
),
),
]);
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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:esc_pos_gen/esc_pos_gen.dart';
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 *`
PosImage(image: image);
// Using `GS v 0` (obsolete)
PosImage.raster(image: image);
// Using `GS ( L`
PosImage.raster(
image: image,
imageFn: PosImageFn.graphics,
);
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Print a Barcode: #
final List<int> barData = [1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 4];
PosBarcode(Barcode.upcA(barData));
// or
// PosBarcode.upcA(barData);
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Print a QR Code: #
Using native ESC/POS commands:
PosQRCode('example.com');
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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());

return PosImage(image: img);
} catch (e) {
print(e);
}
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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');
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All available profiles can be retrieved by calling :
final profiles = await CapabilityProfile.getAvailableProfiles();
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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...)

Thanks to #

esc_pos_utils
esc_pos_utils_plus