NNPrinter Module

Overview

The NNPrinter module provides functionalities for network service discovery and network printing via TCP connections. It supports discovering devices using mDNS (Bonjour) and printing text to network printers. This module is designed to be used with React Native applications.

Permissions

To use network service discovery and network printing, your application needs to request appropriate permissions. This section covers the necessary permissions for both Android and iOS.

Android Permissions

Add the following permissions to your app.json file under the android section:

{
  "expo": {
    ...
    "android": {
      "permissions": [
        "INTERNET",
        "ACCESS_NETWORK_STATE",
        "CHANGE_NETWORK_STATE",
        "ACCESS_WIFI_STATE",
        "CHANGE_WIFI_STATE",
        "NEARBY_WIFI_DEVICES",
        "BLUETOOTH",
        "BLUETOOTH_ADMIN",
        "BLUETOOTH_SCAN",
        "BLUETOOTH_ADVERTISE",
        "BLUETOOTH_CONNECT",
        "ACCESS_FINE_LOCATION",
        "ACCESS_COARSE_LOCATION"
      ],
      "package": "com.yourcompany.yourapp"
    },
    "ios": {
      ...
      "infoPlist": {
        "NSBluetoothAlwaysUsageDescription": "Allow SimpleVen to use bluetooth",
        "NSBonjourServices": [
          "_http._tcp",
          "_ipp._tcp" 
        ],
        "NSLocalNetworkUsageDescription": "This app requires access to the local network to discover and communicate with local devices."     
      }
    },
  }
}

## Usage

### Import and Initialize the Module

```javascript
import NNPrinter from 'nn-printer';

Example Usage

Start Scanning for Devices

NNPrinter.onScanStart().then((status) => {
  console.log('Scan started');
 //status : {"status": "started"}
}).catch(error => {
  console.error('Scan start failed', error);
});

Stop Scanning for Devices

NNPrinter.onScanStop().then((status) => {
  console.log('Scan stopped');
  //{"status": "stopped"}
}).catch(error => {
  console.error('Scan stop failed', error);
});

Listen for Detected Devices

const subscription = NNPrinter.onScanDetected((result) => {
  console.log('Device found:', result.ipAddress);
  //{"ipAddress": "192.168.1.2", "serviceName": "EPSON TM-m30III", "serviceType": "._http._tcp", "status": "found"}
});

// Remember to unsubscribe when no longer needed
subscription.remove();

Print Text to a Network Printer

const const printText =
  "[C]<img>https://drive.usercontent.google.com/u/0/uc?id=1GQOzB8MP3iWXV3k53pFumA5H5s0cpjha&export=download</img>\n"
  +
  NNPrinter.prepareColumn(
    [24],
    ['C'],
    ['SIMPLEVEN TEST'],
    { fontWeight: "bold", fontSize: "big" }
  )
  +
  NNPrinter.prepareColumn(
    [48],
    ['C'],
    ['07/07/2024 18:30']
  ) +
  NNPrinter.prepareColumn(
    [48],
    ['C'],
    ['Accepted by']
  ) +
  NNPrinter.prepareColumn(
    [24],
    ['C'],
    ['Bar'],
    { fontWeight: "bold", fontSize: "big" }
  ) +
  NNPrinter.prepareColumn(
    [48],
    ['C'],
    ['07/07/2024 18:30']
  )
  +
  NNPrinter.prepareColumn(
    [18, 10, 10, 10],
    ['L', 'R', 'R', 'R'],
    ['Item', 'Size', 'Qty', 'Price'],
    { fontWeight: "bold" }
  ) +
  NNPrinter.prepareColumn(
    [18, 10, 10, 10],
    ['L', 'R', 'R', 'R'],
    ['Albabi Odense Pilsner 4.6%', 'Lille', '23', '1058 DKK'],
  ) +
  NNPrinter.prepareColumn(
    [18, 10, 10, 10],
    ['L', 'R', 'R', 'R'],
    ['Pepsi', 'Mellem', '2', '88 DKK'],
  ) +
  NNPrinter.prepareColumn(
    [18, 10, 10, 10],
    ['L', 'R', 'R', 'R'],
    ['Premium Party Starter', '', '1', '799 DKK'],
  ) +
  /** */
  NNPrinter.prepareColumn(
    [48],
    ['L'],
    ['   20x Smirnoff Ice'],
  ) +
  NNPrinter.prepareColumn(
    [48],
    ['L'],
    ['   1x Breezer Original'],
  ) +
  NNPrinter.prepareColumn(
    [48],
    ['L'],
    ['   2x Breezer Pinapple'],
  ) +
  NNPrinter.prepareColumn(
    [48],
    ['L'],
    ['All prices include VAT where applicable'],
  ) +
  NNPrinter.prepareColumn(
    [38, 10],
    ['L', 'R'],
    ['Total', '7147 DKK'],
  ) +
  NNPrinter.prepareColumn(
    [48],
    ['C'],
    ['!!!Disclaimer!!!'],
    { fontWeight: "bold" }
  ) +
  NNPrinter.prepareColumn(
    [48],
    ['C'],
    ['This is a staff-only receipt for internal use only. Please provide official receipts to customers if needed.'],
  )
NNPrinter.print(
  '192.168.1.100', // IP address of the printer
  9100,            // Port
  text, // Text to print
  true,            // Auto cut
  'medium'         // Printer type (as defined in PrinterConfig)
).then(() => {
  console.log('Print successful');
}).catch(error => {
  console.error('Print failed', error);
});

Conclusion

The NNPrinter module provides easy-to-use functionalities for network service discovery and network printing. Ensure you have the required permissions set up correctly for the module to function as expected on both Android and iOS.