Receipt Printer Markup Language (RPML)

Language Overview

Receipt Printer Markup Language (RPML) is a lightweight markup language designed for formatting and generating receipt print documents, eg receipts. RPML provides a set of tags and attributes to control text alignment, styling, and the inclusion of elements like images, barcodes, and tables.

See the language reference for details.

• Language Reference

Usage

This JavaScript package allows you to do the following.

• Parse RPML into commands
• Render commands into an HTML preview
• Encode commands with Receipt Printer Encoder

Note: This package is in alpha and minor updates may include breaking changes.

Installation

npm install rpml

Parse RPML into commands

import { parse } from 'rpml'

const commands = parse('Some RPML markup')

This returns an array of command objects which contain the parsed information. You will likely pass these commands on to the HTML renderer or printer encoder.

Render HTML preview

Use renderHtml to convert the commands into an HTML document for previewing.

This is a full HTML document that is best shown using an iframe.

import { parse, renderHtml } from 'rpml'

const commands = parse('Some RPML markup')
const html = renderHtml({commands})

Or parse and render in one call.

import { parseAndRenderHtml } from 'rpml'

const html = parseAndRenderHtml('Some RPML markup')

These functions accept the following parameters.

• chars: the width of the receipt. Defaults to 32.
• fontFamily: defaults to 'monospace'.
• fontSize: defaults to '14px'.
• lineHeight: defaults to '1.3em'.
• createCanvas: the function for creating a canvas. Defaults to using in-browser document.createElement. You will need to override this if you are calling this through Node.js.

Encode with Receipt Printer Encoder

The encodeReceipt function will apply the parsed commands to Receipt Printer Encoder. It is an asynchornous function to handle loading images.

import ReceiptPrinterEncoder from '@point-of-sale/receipt-printer-encoder'
import { parse, encodeReceipt } from 'rpml'

// Instantiate the encoder
let encoder = new ReceiptPrinterEncoder({
  language: 'esc-pos',
  columns: 42,
  imageMode: 'raster',
})

// Apply RPML commands to the encoder
const commands = parse('Some RPML markup')
encoder = await encodeReceipt({
  commands
  encoder,
  dots: 512,
})

// Print
await currentDevice.transferOut(1, encoder.encode());

Alternatively you can use parseAndEncodeReceipt to do it in one call.

These functions accept the following parameters.

• encoder: the Receipt Printer Encoder to apply the commands to. It should have language and columns set.
• dots: The number of dots wide for the printer.
• createImage: The function used to create an image tag to load the images. Defaults to () => new Image(). You may need to override this if you are calling through Node.js.

Contributing

RPML is in early development. Issues and pull requests are welcome.

To set up your environment, check out this repo and run the following commands.

npm install
npm run test

Also see codemirror-lang-rpml.