thermoprint 0.1.0

Fluent ESC/POS receipt builder for thermal printers — works natively in Rust and in any JavaScript runtime via WASM.

Built by Mamadou Sarr — battle-tested on real POS hardware in Dakar, Senegal.

Features

• ✅ Fluent builder API — chain calls, get bytes
• ✅ 58mm, 80mm, and A4 paper widths
• ✅ Correct money arithmetic with rust_decimal — no float rounding errors
• ✅ CP858 encoding — French, Spanish, Portuguese accents + Euro sign
• ✅ CODE128 barcodes, EAN-13, QR codes
• ✅ Logo / image printing (raster, native feature)
• ✅ Cash drawer kick
• ✅ WASM/npm — same API in browser (WebUSB / WebSerial) and Node.js
• ✅ Zero unsafe code

Installation

Rust / Tauri

[dependencies]
thermoprint  = { version = "0.1", features = ["native"] }  # default; includes image support
rust_decimal = { version = "1", features = ["macros"] }    # for the dec!() macro

Minimal (no image support):

[dependencies]
thermoprint  = { version = "0.1", default-features = false }
rust_decimal = { version = "1", features = ["macros"] }

npm / JavaScript

npm install thermoprint

Rust Usage

use thermoprint::{ReceiptBuilder, PrintWidth, TaxEntry};
use rust_decimal::prelude::*;

let bytes = ReceiptBuilder::new(PrintWidth::Mm80)
    .init()
    .shop_header("MA BOUTIQUE", "+221 77 000 00 00", "Dakar, Sénégal")
    .divider('=')
    .item("Polo Ralph Lauren", 2, dec!(15_000), None)
    .item("Jean Levis 501",    1, dec!(25_000), Some(dec!(2_000)))
    .divider('-')
    .subtotal_ht(dec!(53_000))
    .taxes(&[
        TaxEntry::new("TVA 18%", dec!(9_540), true),
    ])
    .total(dec!(62_540))
    .received(dec!(70_000))
    .change(dec!(7_460))
    .divider('=')
    .barcode_code128("ORD-2024-001")
    .served_by("Mamadou")
    .thank_you("MA BOUTIQUE")
    .feed(3)
    .cut()
    .build(); // → Vec<u8>

// Send `bytes` to your printer however you like.
// thermoprint never touches the OS — that's your call.

With logo (native feature)

let bytes = ReceiptBuilder::new(PrintWidth::Mm80)
    .init()
    .align_center()
    .logo("/path/to/logo.png")? // resized automatically
    .shop_header("MA BOUTIQUE", "+221 77 000 00 00", "Dakar")
    // ...
    .build();

Cash drawer

let bytes = ReceiptBuilder::new(PrintWidth::Mm80)
    .init()
    .open_cash_drawer()
    .build();

JavaScript / TypeScript Usage

import init, { WasmReceiptBuilder } from 'thermoprint';

await init();

// All money amounts are strings — no floating-point surprises
const bytes: Uint8Array = new WasmReceiptBuilder("80mm")
  .init()
  .shopHeader("MA BOUTIQUE", "+221 77 000 00 00", "Dakar, Sénégal")
  .divider("=")
  .item("Polo shirt", 2, "15000", null)
  .item("Jean Levis 501", 1, "25000", "2000")  // with discount
  .divider("-")
  .subtotalHt("53000")
  .total("62540")
  .received("70000")
  .change("7460")
  .divider("=")
  .barcodeCode128("ORD-2024-001")
  .feed(3)
  .cut()
  .build(); // → Uint8Array

// Send to printer via WebUSB / WebSerial / Node.js serial port

WebUSB example

const device = await navigator.usb.requestDevice({ filters: [] });
await device.open();
await device.selectConfiguration(1);
await device.claimInterface(0);
await device.transferOut(1, bytes);

WebSerial example

const port = await navigator.serial.requestPort();
await port.open({ baudRate: 9600 });
const writer = port.writable.getWriter();
await writer.write(bytes);
writer.releaseLock();

API Reference

ReceiptBuilder::new(width: PrintWidth)

Building

# Native
make build

# WASM (browser)
make build-wasm

# WASM (Node.js)
make build-wasm-node

# Tests
make test

# Publish to crates.io
make publish

# Publish to npm
make publish-npm

License

MIT © Mamadou Sarr