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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.

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

QRCode Generator

QRCode Generator

Reference

See Also

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

Conclusion

We learnt 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 feedback.

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