QR Code Generator In ASP.NET Core Using ZXING.NET

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.

• Getting Started With ASP.NET CORE 1.0
• Project Layout In ASP.NET Core 1.0
  
• Middleware And Staticfiles In ASP.NET Core 1.0 - Part One
  
• Middleware And Staticfiles In ASP.NET Core 1.0 - Part Two
  

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.

using Microsoft.AspNetCore.Razor.TagHelpers;
using System;
using System.IO;
using ZXing.QrCode;

Packages required

 

We need the packages given below for drawing and creating QR Code Generator.

"CoreCompat.System.Drawing": "1.0.0-beta006",
"ZXing.Net": "0.15.0"

C#

 

QRCodeTagHelper class given below contains QR Code Generator methods etc.

namespace QRCodeApp {
    [HtmlTargetElement("qrcode")]
    public class QRCodeTagHelper: TagHelper {
        public override void Process(TagHelperContext context, TagHelperOutput output) {
            var QrcodeContent = context.AllAttributes["content"].Value.ToString();
            var alt = context.AllAttributes["alt"].Value.ToString();
            var width = 250; // width of the Qr Code
            var height = 250; // height of the Qr Code
            var margin = 0;
            var qrCodeWriter = new ZXing.BarcodeWriterPixelData {
                Format = ZXing.BarcodeFormat.QR_CODE,
                    Options = new QrCodeEncodingOptions {
                        Height = height, Width = width, Margin = margin
                    }
            };
            var pixelData = qrCodeWriter.Write(QrcodeContent);
            // creating a bitmap from the raw pixel data; if only black and white colors are used it makes no difference
            // that the pixel data ist BGRA oriented and the bitmap is initialized with RGB
            using(var bitmap = new System.Drawing.Bitmap(pixelData.Width, pixelData.Height, System.Drawing.Imaging.PixelFormat.Format32bppRgb))
            using(var ms = new MemoryStream()) {
                var bitmapData = bitmap.LockBits(new System.Drawing.Rectangle(0, 0, pixelData.Width, pixelData.Height), System.Drawing.Imaging.ImageLockMode.WriteOnly, System.Drawing.Imaging.PixelFormat.Format32bppRgb);
                try {
                    // we assume that the row stride of the bitmap is aligned to 4 byte multiplied by the width of the image
                    System.Runtime.InteropServices.Marshal.Copy(pixelData.Pixels, 0, bitmapData.Scan0, pixelData.Pixels.Length);
                } finally {
                    bitmap.UnlockBits(bitmapData);
                }
                // save to stream as PNG
                bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
                output.TagName = "img";
                output.Attributes.Clear();
                output.Attributes.Add("width", width);
                output.Attributes.Add("height", height);
                output.Attributes.Add("alt", alt);
                output.Attributes.Add("src", String.Format("data:image/png;base64,{0}", Convert.ToBase64String(ms.ToArray())));
            }
        }
    }
}

Index.chtml

 

The code given below will display QR Code Generator.

@{
    ViewData["Title"] = "Home";
}

<h2>@ViewData["Title"].</h2>
<h3>@ViewData["Message"]</h3>

A library which supports decoding and generating of barcodes (like QR Code, PDF 417, EAN, UPC, Aztec, Data Matrix, Codabar) within images.

<qrcode alt="QR Code" content="https://rajeeshmenoth.wordpress.com/" />
 https://rajeeshmenoth.wordpress.com/

_ViewImports.cshtml

 

The code Injecting TagHelper given below is in the entire Application.

@addTagHelper "*, QRCodeApp"

project.json

 

The dependencies given below are required to create QR Code Application.

{
  "dependencies": {
    "Microsoft.AspNetCore.Diagnostics": "1.0.0",
    "Microsoft.AspNetCore.Mvc": "1.1.2",
    "Microsoft.AspNetCore.Mvc.Core": "1.1.2",
    "Microsoft.AspNetCore.Server.IISIntegration": "1.0.0",
    "Microsoft.AspNetCore.Server.Kestrel": "1.0.1",
    "Microsoft.AspNetCore.StaticFiles": "1.1.1",
    "Microsoft.Extensions.Logging.Console": "1.0.0",
    "CoreCompat.System.Drawing": "1.0.0-beta006",
    "ZXing.Net": "0.15.0"
  },

  "tools": {
    "Microsoft.AspNetCore.Server.IISIntegration.Tools": "1.0.0-preview2-final"
  },

  "frameworks": {
    "net452": { }
  },

  "buildOptions": {
    "emitEntryPoint": true,
    "preserveCompilationContext": true
  },

  "publishOptions": {
    "include": [
      "wwwroot",
      "web.config"
    ]
  },

  "scripts": {
    "postpublish": [ "dotnet publish-iis --publish-folder %publish:OutputPath% --framework %publish:FullTargetFramework%" ]
  }
}

Output

 

Reference

• Micjahn/Zxing.Net
• Discussion
  
• TechBlog Content
  

See Also

 

You can download other ASP.NET Core 1.0 source codes from MSDN Code, using the link, mentioned below.

•  MSDN Gallery Samples

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.