README.md

qrcodenet-core

This is a fork of the old https://archive.codeplex.com/?p=qrcodenet with everything but SVG rendering removed and rebuilt under .NET Core 3.1

My "itch" is I just needed a QR code dumped out on a page as an SVG. I used in combination with PureOtp and Base32 library.

Here's how I use it in my ASP.NET Core app:

1. Create a shared secret

    this.SharedSecret = Base32Encoder.Encode(KeyGeneration.GenerateRandomKey(10));
   

2. Mangle it into a URL

    this.QRCodeUrl = $"otpauth://totp/Contoso?secret={this.SharedSecret}";
   

3. Spit out a tag helper on your Razor page

    <svt-qr-code content="@Model.QRCodeUrl"></svt-qr-code>
   

4. Write the tag helper

    [HtmlTargetElement("svt-qr-code")]
    public class QRCodeTagHelper : TagHelper
    {
        public string? Content
        {
            get;
            set;
        }
   
        public override async Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
        {
            await base.ProcessAsync(context, output);
   
            var encoder = new QrEncoder(ErrorCorrectionLevel.H);
            var encoded = encoder.Encode(this.Content);
            var renderer = new SVGRenderer(
                new FixedCodeSize(200, QuietZoneModules.Two), 
                new FormColor(Color.Black), 
                new FormColor(Color.White));
            var svg = renderer.WriteToString(encoded.Matrix, true);
            output.Content.SetHtmlContent(svg);
        }
    }
   

Perhaps I am a fool. It works for me.