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

Article
1/17/2024

Note: This article Participated in TechNet Guru Competition May 2017 and won Silver Medal.

Introduction

In this article, we will explain how to create a QR Code Generator in ASP.NET Core 1.0, using Zxing.Net.

Background

We 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. We searched a lot on Google but finally found "Zxing.Net" and it is a library, which supports decoding and generating of the barcodes. We 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.

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

Downloads

You can download ASP.NET Core 1.0 source code from the MSDN Code using the links mentioned below.

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