@finan-me/react-native-thermal-printer

React Native library for ESC/POS thermal printers with Bluetooth, BLE, and LAN support.

Features

• ✅ Multi-connection: Bluetooth Classic, BLE, LAN/WiFi
• ✅ Vietnamese support: Full CP1258 encoding
• ✅ Rich printing: Text, images, QR, barcodes, tables
• ✅ Multi-printer: Print to multiple printers concurrently
• ✅ Margin & Alignment: Consistent margins across all printer types
• ✅ Cross-platform: Android & iOS

Installation

yarn add @finan-me/react-native-thermal-printer

iOS Setup

cd ios && pod install

Add to Info.plist:

<!-- Required: Bluetooth access for connecting to printers -->
<key>NSBluetoothAlwaysUsageDescription</key>
<string>This app needs Bluetooth access to connect to thermal printers for receipt printing</string>

<!-- iOS 13+: Required for discovering BLE printers -->
<key>NSBluetoothPeripheralUsageDescription</key>
<string>This app needs Bluetooth to discover and connect to thermal printers</string>

Notes:

• iOS primarily uses BLE for thermal printers
• Bluetooth Classic requires MFi certification (most printers don't have)
• User will see permission prompt on first Bluetooth access

Android Setup

Add to AndroidManifest.xml:

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <!-- ========== NETWORK PERMISSIONS ========== -->
    <!-- Required: For LAN/WiFi printing -->
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

    <!-- ========== ANDROID 12+ (API 31+) ========== -->
    <!-- Required: Scan for Bluetooth devices -->
    <uses-permission
        android:name="android.permission.BLUETOOTH_SCAN"
        android:usesPermissionFlags="neverForLocation"
        tools:targetApi="31" />

    <!-- Required: Connect to Bluetooth devices -->
    <uses-permission
        android:name="android.permission.BLUETOOTH_CONNECT"
        tools:targetApi="31" />

    <!-- ========== ANDROID 11 AND BELOW (API ≤30) ========== -->
    <!-- Required: Legacy Bluetooth permissions -->
    <uses-permission
        android:name="android.permission.BLUETOOTH"
        android:maxSdkVersion="30" />
    <uses-permission
        android:name="android.permission.BLUETOOTH_ADMIN"
        android:maxSdkVersion="30" />

    <!-- Required: BLE scan requires location on API ≤30 -->
    <uses-permission
        android:name="android.permission.ACCESS_FINE_LOCATION"
        android:maxSdkVersion="30" />

</manifest>

Permission Explanations:

| Permission | API Level | Purpose | Required? | | ---------------------- | --------- | ---------------------------- | -------------------- | | BLUETOOTH_SCAN | 31+ | Scan for Bluetooth devices | ✅ Yes | | BLUETOOTH_CONNECT | 31+ | Connect to Bluetooth devices | ✅ Yes | | BLUETOOTH | ≤30 | Legacy Bluetooth access | ✅ Yes (old Android) | | BLUETOOTH_ADMIN | ≤30 | Legacy Bluetooth discovery | ✅ Yes (old Android) | | ACCESS_FINE_LOCATION | ≤30 | BLE scan on old Android | ✅ Yes (old Android) | | INTERNET | All | LAN/WiFi printing | ✅ Yes | | ACCESS_NETWORK_STATE | All | Check network connectivity | ✅ Yes |

neverForLocation Flag:

<uses-permission
    android:name="android.permission.BLUETOOTH_SCAN"
    android:usesPermissionFlags="neverForLocation"
    tools:targetApi="31" />

• Purpose: Tells Android you DON'T use Bluetooth for location tracking
• Effect: User won't see "Location" in permission prompt
• When to use: When you ONLY scan Bluetooth for printers (not for location)

Without neverForLocation: ❌ "App wants to access Bluetooth and Location" With neverForLocation: ✅ "App wants to access Nearby devices"

Runtime Permissions:

import {PermissionsAndroid, Platform} from 'react-native'

async function requestBluetoothPermissions() {
  if (Platform.OS === 'android') {
    if (Platform.Version >= 31) {
      // Android 12+
      const granted = await PermissionsAndroid.requestMultiple([
        PermissionsAndroid.PERMISSIONS.BLUETOOTH_SCAN,
        PermissionsAndroid.PERMISSIONS.BLUETOOTH_CONNECT,
      ])

      return (
        granted['android.permission.BLUETOOTH_SCAN'] === 'granted' &&
        granted['android.permission.BLUETOOTH_CONNECT'] === 'granted'
      )
    } else {
      // Android 11 and below
      const granted = await PermissionsAndroid.request(PermissionsAndroid.PERMISSIONS.ACCESS_FINE_LOCATION)
      return granted === 'granted'
    }
  }

  return true // iOS handles automatically
}

// Use before scanning
const hasPermission = await requestBluetoothPermissions()
if (hasPermission) {
  await ThermalPrinter.scanDevices()
}

Quick Start

import {ThermalPrinter} from '@finan-me/react-native-thermal-printer'

// 1. Scan devices
const {paired, found} = await ThermalPrinter.scanDevices()

// 2. Print receipt
const job = {
  printers: [
    {
      address: 'bt:AA:BB:CC:DD:EE:FF',
      options: {
        paperWidthMm: 58,
        encoding: 'CP1258', // Vietnamese
        marginMm: 1, // 1mm margin each side (default)
      },
    },
  ],
  documents: [
    [
      // Header
      {type: 'text', content: 'COFFEE SHOP', style: {align: 'center', bold: true, size: 'double'}},
      {type: 'text', content: '123 Main St', style: {align: 'center'}},
      {type: 'line'},

      // Table
      {
        type: 'table',
        headers: ['Item', 'Qty', 'Price'],
        rows: [
          ['Cappuccino', '2', '90.000đ'],
          ['Sandwich', '1', '35.000đ'],
        ],
        columnWidths: [50, 20, 30],
        alignments: ['left', 'center', 'right'],
      },

      // Total
      {type: 'line'},
      {type: 'text', content: 'TOTAL: 125.000đ', style: {bold: true, size: 'double_width'}},

      // QR payment
      {type: 'qr', content: 'https://payment.link/123', size: 6, align: 'center'},

      // Footer
      {type: 'text', content: 'Cảm ơn quý khách!', style: {align: 'center'}},
      {type: 'feed', lines: 3},
      {type: 'cut'},
    ],
  ],
}

await ThermalPrinter.printReceipt(job)

Address Format

| Type | Format | Example | | ----------------- | ------------- | ------------------------ | | Bluetooth Classic | bt:MAC | bt:AA:BB:CC:DD:EE:FF | | BLE | ble:MAC | ble:AA:BB:CC:DD:EE:FF | | LAN/WiFi | lan:IP:PORT | lan:192.168.1.100:9100 |

Supported Content Types

Text: {type: 'text', content: 'Hello', style: {align: 'center', bold: true, size: 'double'}}

Line: {type: 'line'}

Table: {type: 'table', headers: ['A', 'B'], rows: [['1', '2']], columnWidths: [50, 50]}

Columns: {type: 'columns', columns: [{content: 'Left', width: 50}, {content: 'Right', width: 50, align: 'right'}]}

QR Code: {type: 'qr', content: 'https://...', size: 6, align: 'center'}

Barcode: {type: 'barcode', content: '123456', format: 'CODE128', align: 'center'}

Image: {type: 'image', imagePath: '/path/to/image.png', options: {align: 'center', marginMm: 2}}

Feed: {type: 'feed', lines: 3}

Spacer: {type: 'spacer', height: 2, fill: '-'}

Cut: {type: 'cut', partial: true}

Options

Printer Options

{
  paperWidthMm?: 32 | 58 | 80,             // default: 58
  encoding?: 'CP1258' | 'UTF8' | 'ASCII',  // default: CP1258
  marginMm?: number,                        // default: 1mm each side
  keepAlive?: boolean
}

Job Options

{
  concurrent?: boolean,        // print to multiple printers in parallel
  continueOnError?: boolean,   // continue if one printer fails
  onProgress?: (completed: number, total: number) => void,
  onJobComplete?: (address: string, success: boolean) => void
}

Print Configuration

{
  address: string,
  copies?: number,              // number of copies (default: 1)
  delayBetweenCopies?: number,  // delay in ms (default: 200)
  options?: PrinterOptions
}

Multi-Printer Printing

const job = {
  printers: [
    {address: 'bt:11:11:11:11:11:11', copies: 2}, // Kitchen: 2 copies
    {address: 'lan:192.168.1.100:9100'}, // Counter: 1 copy
  ],
  documents: [[{type: 'text', content: 'Order #123'}, {type: 'cut'}]],
  options: {
    concurrent: true, // Print in parallel
    continueOnError: true,
    onProgress: (completed, total) => console.log(`${completed}/${total}`),
  },
}

const result = await ThermalPrinter.printReceipt(job)
// result.success, result.results (per-printer status)

Vietnamese Support

{
  options: {
    encoding: 'CP1258'
  }
}

Error Handling

try {
  await ThermalPrinter.printReceipt(job)
} catch (error) {
  console.log(error.code) // E1001, E2001, E4003...
  console.log(error.message) // Human readable
  console.log(error.suggestion) // How to fix
  console.log(error.retryable) // Can retry?
}

Troubleshooting

Vietnamese not printing?

• Use encoding: 'CP1258'
• Test with testCodepages() utility

Connection timeout?

• Check printer is on and in range
• Use testConnection() before printing

Image not printing?

• Use local file path (not base64)
• Images auto-resize to paper width

License

MIT