@decky.fx/react-native-printer

Warning Experimental

react-native-printer

printing on react-native

modified from https://github.com/DantSu/ESCPOS-ThermalPrinter-Android, written in full Kotlin, using latest sdk, and modern language like coroutines etc.

Notable change from DantSu's

• Expose it as react-native's Native Module
• Add devices scan methods
• Allow to pass image file path uri or URL for <img> tag's payload

const data = '<img>file:///sdcard/image.png</img>'

Feature

• Scan Local Network using Socket
• Scan Local Network using Zeroconf
• Scan Paired Bluetooth Devices
• Scan USB Devices
• Scan Serial Devices
• Print to Network Printer
• [s] Print to Paired Bluetooth Printer
• Print to USB Printer
• Print to Serial Devices
• Queue Job Printing using AndroidWorker

Installation

npm install @decky.fx/react-native-printer --save

or

yarn add @decky.fx/react-native-printer

Latest Working Version

1.0.5-g

Tested Printer

• SEWOO SLK-TS100
• POWERBANK A6
• EPPOS EP-RPP02

Development Instructions

• clone this repo
• yarn install
• cd example && yarn install
• if something wrong use yarn install --ignore-engines
• recommmended node version are v16.16.0 or v18.16.1
• within example directory: yarn start

Torubleshoots

to use in older react-native project you may need to edit project build.gradle file

edit

minCompileSdk

add

mavenCentral()
maven { url "https://maven.google.com" }

and

classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.8.22"

Usage

// Import modules
import {
  RNPrinter,
  DeviceScanner,
  RNPrinterEventEmitter,
  DeviceScannerEventEmitter,
} from '@decky.fx/react-native-printer';

// Listen various event
RNPrinterEventEmitter.onEvents((event, payload) => {});
DeviceScannerEventEmitter.onEvents((event, payload) => {});

// Scan usb devices
DeviceScanner.scan(DeviceScanner.SCAN_USB);

// Design the print output
const builder = new DesignBuilder(RNPrinter.PRINTING_LINES_MAX_CHAR_42);
builder.addLine('Print me');
builder.addLine(TagHelper.left('I am at left'));
builder.addLine(TagHelper.center('I am centered'));
builder.addLine(TagHelper.right('I am at right'));
builder.addLine(TagHelper.center(TagHelper.bold('I am bold')));
builder.addLine(TagHelper.center(TagHelper.underline('I am underlined')));
builder.addLine(TagHelper.center(TagHelper.barcode('barcode data')));
builder.addLine(TagHelper.center(TagHelper.qrcode('qrcode data')));
builder.addLine(TagHelper.center(TagHelper.image('image source')));

// Build printing job
const printer = {
  connection: RNPrinter.PRINTER_CONNECTION_BLUETOOTH,
  address: "00:00:00:00:00",
}
const jobId = await JobBuilder.begin();
await JobBuilder.selectPrinter(jobId, printer);
await JobBuilder.initializePrinter(jobId);
// Build the design
const designBuilder = new DesignBuilder(
  RNPrinter.PRINTING_LINES_MAX_CHAR_40
);
designBuilder.addLine('Print something')
// Put all design
for (let i = 0; i < designBuilder.designs.length; i++) {
  let line = designBuilder.designs[i]!!;
  await JobBuilder.printLine(jobId, line);
}
await JobBuilder.cutPaper(jobId);
await JobBuilder.openCashBox(jobId);

// execute job
const job = await JobBuilder.build(jobId);
// RNPrinter.enqueuePrint(job);
RNPrinter.enqueuePrint(job, printer);

// Another way
RNPrinter.write(RNPrinter.PRINTER_CONNECTION_USB, '/dev/usb/001/003', `[C]<img>${imageUri}</img>\n"` + '[L]\n'

// Write to usb device 
RNPrinter.write({
  connection: RNPrinter.PRINTER_CONNECTION_USB,
  address: '/dev/usb/001/003',
}, RNPrinter.TEST_PRINT_DESIGN);

// unsubscribe listeners if no longer needed
RNPrinterEventEmitter.offEvents();
DeviceScannerEventEmitter.offEvents();

API

Constants

TODO

• Scan Local Network using Socket
• Scan Local Network using Zeroconf
• Scan Paired Bluetooth Devices
• Scan USB Devices
• Scan Serial Devices
• Print to Network Printer
• Print Paired to Bluetooth Printer
• Print to USB Printer
• Print to Serial Devices
• Queue Job Printing using AndroidWorker
• iOS Implementation

Formatted text : syntax guide

New line

Use \n to create a new line of text.

Text alignment and column separation

Add an alignment tag on a same line of text implicitly create a new column.

Column alignment tags :

• [L] : left side alignment
• [C] : center alignment
• [R] : right side alignment

Example :

• [L]Some text : One column aligned to left
• [C]Some text : One column aligned to center
• [R]Some text : One column aligned to right
• [L]Some text[L]Some other text : Two columns aligned to left. Some other text starts in the center of the paper.
• [L]Some text[R]Some other text : Two columns, first aligned to left, second aligned to right. Some other text is printed at the right of paper.
• [L]Some[R]text[R]here : Three columns.
• [L][R]text[R]here : Three columns. The first is empty but it takes a third of the available space.

Font

Size

<font></font> tag allows you to change the font size and color. Default size is normal / black.

• <font size='normal'>Some text</font> : Normal size

• <font size='wide'>Some text</font> : Double width of medium size

• <font size='tall'>Some text</font> : Double height of medium size

• <font size='big'>Some text</font> : Double width and height of medium size

• <font size='big-2'>Some text</font> : 3 x width and height

• <font size='big-3'>Some text</font> : 4 x width and height

• <font size='big-4'>Some text</font> : 5 x width and height

• <font size='big-5'>Some text</font> : 6 x width and height

• <font size='big-6'>Some text</font> : 7 x width and height

• <font color='black'>Some text</font> : black text - white background

• <font color='bg-black'>Some text</font> : white text - black background

• <font color='red'>Some text</font> : red text - white background (Not working on all printer)

• <font color='bg-red'>Some text</font> : white text - red background (Not working on all printer)

Bold

<b></b> tag allows you to change the font weight.

• <b>Some text</b>

Underline

<u></u> tag allows you to underline the text.

• <u>Some text</u> text underlined
• <u type='double'>Some text</u> text double-strike (Not working on all printer)

Image

<img></img> tag allows you to print image. Inside the tag you need to write a hexadecimal string of an image.

Use PrinterTextParserImg.bitmapToHexadecimalString to convert Drawable, BitmapDrawable or Bitmap to hexadecimal string.

• <img>hexadecimal string of an image</img>

⚠ WARNING ⚠ : This tag has several constraints :

• A line that contains <img></img> can have only one alignment tag and it must be at the beginning of the line.
• <img> must be directly preceded by nothing or an alignment tag ([L][C][R]).
• </img> must be directly followed by a new line \n.
• You can't write text on a line that contains <img></img>.
• Maximum height of printed image is 256px, If you want to print larger bitmap. Please refer to this solution: #70

Barcode

<barcode></barcode> tag allows you to print a barcode. Inside the tag you need to write the code number to print.

• <barcode>451278452159</barcode> : (12 numbers)
  Prints a EAN13 barcode (height: 10mm, width: ~70% printer width, text: displayed below).
• <barcode type='ean8'>4512784</barcode> : (7 numbers)
  Prints a EAN8 barcode (height: 10mm, width: ~70% printer width, text: displayed below).
• <barcode type='upca' height='20'>4512784521</barcode> : (11 numbers)
  Prints a UPC-A barcode (height: 20mm, width: ~70% printer width, text: displayed below).
• <barcode type='upce' height='25' width='50' text='none'>512789</barcode> : (6 numbers)
  Prints a UPC-E barcode (height: 25mm, width: ~50mm, text: hidden).
• <barcode type='128' width='40' text='above'>DantSu</barcode> : (string)
  Prints a barcode 128 (height: 10mm, width: ~40mm, text: displayed above).

⚠ WARNING ⚠ : This tag has several constraints :

• A line that contains <barcode></barcode> can have only one alignment tag and it must be at the beginning of the line.
• <barcode> must be directly preceded by nothing or an alignment tag ([L][C][R]).
• </barcode> must be directly followed by a new line \n.
• You can't write text on a line that contains <barcode></barcode>.

QR Code

<qrcode></qrcode> tag allows you to print a QR code. Inside the tag you need to write the QR code data.

• <qrcode>https://dantsu.com/</qrcode> : Prints a QR code with a width and height of 20 millimeters.
• <qrcode size='25'>123456789</qrcode> : Prints a QR code with a width and height of 25 millimeters.

⚠ WARNING ⚠ : This tag has several constraints :

• A line that contains <qrcode></qrcode> can have only one alignment tag and it must be at the beginning of the line.
• <qrcode> must be directly preceded by nothing or an alignment tag ([L][C][R]).
• </qrcode> must be directly followed by a new line \n.
• You can't write text on a line that contains <qrcode></qrcode>.

Contributing

See the contributing guide to learn how to contribute to the repository and the development workflow.

License

MIT

Made with create-react-native-library