Generate QR Codes for URLs

// Using qrcode library (npm install qrcode)
import QRCode from 'qrcode';

// Generate QR code as Data URL
async function generateQRCode(url, options = {}) {
  try {
    const qrDataURL = await QRCode.toDataURL(url, {
      width: options.width || 300,
      margin: options.margin || 4,
      color: {
        dark: options.darkColor || '#000000',
        light: options.lightColor || '#FFFFFF'
      },
      errorCorrectionLevel: options.errorLevel || 'M' // L, M, Q, H
    });
    
    return qrDataURL;
  } catch (err) {
    console.error('QR generation failed:', err);
    throw err;
  }
}

// Generate QR for campaign URL
async function generateCampaignQR(baseUrl, campaign) {
  // Add UTM parameters
  const url = new URL(baseUrl);
  url.searchParams.set('utm_source', 'qr_code');
  url.searchParams.set('utm_medium', 'print');
  url.searchParams.set('utm_campaign', campaign);
  
  // Generate QR code
  const qrCode = await generateQRCode(url.toString());
  
  return qrCode;
}

// Usage in browser
async function displayQR() {
  const qrDataURL = await generateQRCode('https://example.com');
  
  // Display in img element
  const img = document.createElement('img');
  img.src = qrDataURL;
  document.body.appendChild(img);
}

// Generate and download
async function downloadQR(url, filename = 'qrcode.png') {
  const qrDataURL = await generateQRCode(url);
  
  const link = document.createElement('a');
  link.href = qrDataURL;
  link.download = filename;
  link.click();
}

// React component
function QRCodeComponent({ url }) {
  const [qrCode, setQRCode] = React.useState('');
  
  React.useEffect(() => {
    generateQRCode(url).then(setQRCode);
  }, [url]);
  
  return <img src={qrCode} alt="QR Code" />;
}

# Using qrcode library (pip install qrcode[pil])
import qrcode
from io import BytesIO

def generate_qr_code(url, size=10, border=4):
    # Create QR code instance
    qr = qrcode.QRCode(
        version=1,
        error_correction=qrcode.constants.ERROR_CORRECT_M,
        box_size=size,
        border=border,
    )
    
    # Add data
    qr.add_data(url)
    qr.make(fit=True)
    
    # Create image
    img = qr.make_image(fill_color="black", back_color="white")
    
    return img

# Save to file
def save_qr_code(url, filename='qrcode.png'):
    img = generate_qr_code(url)
    img.save(filename)

# Generate for campaign
def generate_campaign_qr(base_url, campaign):
    url = f"{base_url}?utm_source=qr_code&utm_medium=print&utm_campaign={campaign}"
    return generate_qr_code(url)

# Usage
save_qr_code('https://example.com', 'my_qr.png')