Introduction
In this article, we will explain how to create a QR Code Generator in ASP.NET Core 1.0, using Zxing.Net.
Background
I tried to create a QR Code Generator in ASP.NET Core, using third party libraries but in most of the cases codes are not fully supported in ASP.NET Core because of some version issues etc. I searched a lot in Google but finally I found "Zxing.Net" and it is a library, which supports decoding and generating of the barcodes. I had a discussion with MicJahn and came up with a great solution.
Before reading this article, you must read the articles given below for ASP.NET Core knowledge.
Zxing.Net
A library, which supports decoding and generating of the barcodes (Example: QR Code, PDF 417, EAN, UPC, Aztec, Data Matrix, Codabar) within the images.
Assemblies required
The assemblies given below are required for QR Code Generator.
  1. using Microsoft.AspNetCore.Razor.TagHelpers;
  2. using System;
  3. using System.IO;
  4. using ZXing.QrCode;
Packages required
We need the packages given below for drawing and creating QR Code Generator.
  1. "CoreCompat.System.Drawing": "1.0.0-beta006",
  2. "ZXing.Net": "0.15.0"
C#
QRCodeTagHelper class given below contains QR Code Generator methods etc.
  1. namespace QRCodeApp {
  2. [HtmlTargetElement("qrcode")]
  3. public class QRCodeTagHelper: TagHelper {
  4. public override void Process(TagHelperContext context, TagHelperOutput output) {
  5. var QrcodeContent = context.AllAttributes["content"].Value.ToString();
  6. var alt = context.AllAttributes["alt"].Value.ToString();
  7. var width = 250; // width of the Qr Code
  8. var height = 250; // height of the Qr Code
  9. var margin = 0;
  10. var qrCodeWriter = new ZXing.BarcodeWriterPixelData {
  11. Format = ZXing.BarcodeFormat.QR_CODE,
  12. Options = new QrCodeEncodingOptions {
  13. Height = height, Width = width, Margin = margin
  14. }
  15. };
  16. var pixelData = qrCodeWriter.Write(QrcodeContent);
  17. // creating a bitmap from the raw pixel data; if only black and white colors are used it makes no difference
  18. // that the pixel data ist BGRA oriented and the bitmap is initialized with RGB
  19. using(var bitmap = new System.Drawing.Bitmap(pixelData.Width, pixelData.Height, System.Drawing.Imaging.PixelFormat.Format32bppRgb))
  20. using(var ms = new MemoryStream()) {
  21. var bitmapData = bitmap.LockBits(new System.Drawing.Rectangle(0, 0, pixelData.Width, pixelData.Height), System.Drawing.Imaging.ImageLockMode.WriteOnly, System.Drawing.Imaging.PixelFormat.Format32bppRgb);
  22. try {
  23. // we assume that the row stride of the bitmap is aligned to 4 byte multiplied by the width of the image
  24. System.Runtime.InteropServices.Marshal.Copy(pixelData.Pixels, 0, bitmapData.Scan0, pixelData.Pixels.Length);
  25. } finally {
  26. bitmap.UnlockBits(bitmapData);
  27. }
  28. // save to stream as PNG
  29. bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
  30. output.TagName = "img";
  31. output.Attributes.Clear();
  32. output.Attributes.Add("width", width);
  33. output.Attributes.Add("height", height);
  34. output.Attributes.Add("alt", alt);
  35. output.Attributes.Add("src", String.Format("data:image/png;base64,{0}", Convert.ToBase64String(ms.ToArray())));
  36. }
  37. }
  38. }
  39. }
Index.chtml
The code given below will display QR Code Generator.
  1. @{
  2. ViewData["Title"] = "Home";
  3. }
  5. <h2>@ViewData["Title"].</h2>
  6. <h3>@ViewData["Message"]</h3>
  8. A library which supports decoding and generating of barcodes (like QR Code, PDF 417, EAN, UPC, Aztec, Data Matrix, Codabar) within images.
  10. <qrcode alt="QR Code" content="https://rajeeshmenoth.wordpress.com/" />
  11. https://rajeeshmenoth.wordpress.com/
_ViewImports.cshtml
The code Injecting TagHelper given below is in the entire Application.
  1. @addTagHelper "*, QRCodeApp"
project.json
The dependencies given below are required to create QR Code Application.
  1. {
  2. "dependencies": {
  3. "Microsoft.AspNetCore.Diagnostics": "1.0.0",
  4. "Microsoft.AspNetCore.Mvc": "1.1.2",
  5. "Microsoft.AspNetCore.Mvc.Core": "1.1.2",
  6. "Microsoft.AspNetCore.Server.IISIntegration": "1.0.0",
  7. "Microsoft.AspNetCore.Server.Kestrel": "1.0.1",
  8. "Microsoft.AspNetCore.StaticFiles": "1.1.1",
  9. "Microsoft.Extensions.Logging.Console": "1.0.0",
  10. "CoreCompat.System.Drawing": "1.0.0-beta006",
  11. "ZXing.Net": "0.15.0"
  12. },
  14. "tools": {
  15. "Microsoft.AspNetCore.Server.IISIntegration.Tools": "1.0.0-preview2-final"
  16. },
  18. "frameworks": {
  19. "net452": { }
  20. },
  22. "buildOptions": {
  23. "emitEntryPoint": true,
  24. "preserveCompilationContext": true
  25. },
  27. "publishOptions": {
  28. "include": [
  29. "wwwroot",
  30. "web.config"
  31. ]
  32. },
  34. "scripts": {
  35. "postpublish": [ "dotnet publish-iis --publish-folder %publish:OutputPath% --framework %publish:FullTargetFramework%" ]
  36. }
  37. }
Output

Reference
See Also
You can download other ASP.NET Core 1.0 source codes from MSDN Code, using the link, mentioned below.
Conclusion
We learned how to create a QR Code Generator in ASP.NET Core 1.0, using Zxing.Net. I hope you liked this article. Please share your valuable suggestions and the feedback.