Create QR Codes with .NET

QR codes are a simple and very popular way of exchanging data and information - even in .NET. They have become part of everyday life.

Unfortunately, .NET does not natively support the generation of QRCodes; we have to rely on the community. Fortunately, there is a very good library that we can use: QRCoder by Raffael Herrmann.

Install QRCoder

The installation is simple. We can install the library via NuGet:

dotnet add package QRCoder

Using QRCoder

The structure and use of the library is very simple: we basically just need to create an instance of the QRCodeGenerator class and call the CreateQrCode method. The CreateQrCode method returns a QRCodeData object, which we can then convert into a Bitmap object.

A more realistic example is that we abstract the generation of the QRCode into a provider, which allows us to separate the implementation from the use and also to implement unit tests more easily.

// Defining the QRCodeProvider class
// Add an interface to your code!
public class QRCodeProvider
{
    // Creating a new instance of QRCodeGenerator
    // In principle, this class supports IDisposable, but we can re-use this instance
    private static readonly QRCodeGenerator s_qrGenerator = new();

    // Method to generate the QR code
    public byte[] GeneratePng(string text)
    {
        // Creating the QR code data with our defaults
        using QRCodeData qrCodeData = s_qrGenerator.CreateQrCode(text, QRCodeGenerator.ECCLevel.Q);

        // Creating a new instance of PngByteQRCode with the QR code data
        // We can also use other Image types, like BitmapByteQRCode
        PngByteQRCode qrCode = new (qrCodeData);

        // Returning the QR code as a graphic
        return qrCode.GetGraphic(pixelsPerModule: 20);
    }
}

The QRCodeProvider class can now either be used directly or integrated cleanly into a dependency injection container with an additional interface.

By calling the provider, we can generate our QRCode as a PNG with a handful of code - in this example stored on the file system.

// NuGet: https://github.com/codebude/QRCoder
using QRCoder;

namespace BenjaminAbt_Samples_QrCode // Defining the namespace
{
    internal class Program // Defining the Program class
    {
        static void Main(string[] args)
        {
            // Creating a new instance of QRCodeProvider
            // This is our own abstraction
            QRCodeProvider qrCodeProvider = new();

            // Defining the path where the QR code will be saved
            // You can use different types of images and also svg or In-Memory
            string path = @"C:\temp\qrcodetest.png";

            string sampleText = "Hello World";

            // Generating the QR code
            byte[] png = qrCodeProvider.GeneratePng(sampleText);

            File.WriteAllBytes(path, png); // Writing the QR code to the file
        }
    }

    // QRCodeProvider here
}