Quarer

A fast and simple-to-use QR code encoding library.

By vectorizing many parts of the QR Code creation process, Quarer manages to be much faster than many other libraries. Quarer supports ECI mode encoding as well as Kanji.

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Installation

dotnet add package Quarer

Usage

Create a QR Code

using Quarer;

var qrCode = QrCode.Create("Hello, World!");

Console.WriteLine(qrCode.Version);
Console.WriteLine(qrCode.Width);
Console.WriteLine(qrCode.ErrorCorrectionLevel);

Output the QR code using a tool of your choice. The example below outputs directly to the console:

Console.WriteLine("Encoding \"Hello, World!\"");

var qrCode = QrCode.Create("Hello, World");

var sb = new StringBuilder();

OutputYPadding(sb, qrCode.Width);
for (var y = 0; y < qrCode.Height; y++)
{
    for (var x = -4; x < qrCode.Width + 4; x++)
    {
        if (x < 0 || x >= qrCode.Width)
        {
            sb.Append("██");
            continue;
        }

        var v = qrCode.Data[x, y] != 0;
        var s = v ? "  " : "██";
        sb.Append(s);
    }
    sb.AppendLine();
}
OutputYPadding(sb, qrCode.Width);

Console.WriteLine(sb.ToString());

static void OutputYPadding(StringBuilder sb, int width)
{
    for (var y = 0; y < 4; y++)
    {
        for (var x = 0; x < width + 8; x++)
        {
            sb.Append('█');
            sb.Append('█');
        }
        sb.AppendLine();
    }
}

See more samples.

Features

Automatic Latin1 detection

Byte-mode encoding for a QR Code defaults to Latin1. Quarer detects when it could be beneficial to transcode a string to Latin1, otherwise, Quarer defaults to UTF-8. Latin1 is a more compact encoding than UTF-8 for some characters. In addition, Quarer can also skip emitting the ECI indicator for such a case.

var s = "Ã";
Console.WriteLine(Encoding.UTF8.GetBytes(s).Length); // 2
Console.WriteLine(Encoding.Latin1.GetBytes(s).Length); // 1

Encode at a specific error correction level

var qrCodeEncodingOptions = new QrCodeEncodingOptions
{
    ErrorCorrectionLevel = ErrorCorrectionLevel.H
};
var qrCode = QrCode.Create("Hello, World!", qrCodeEncodingOptions);

Encode using a specific version

var qrCodeEncodingOptions = new QrCodeEncodingOptions
{
    Version = QrVersion.GetVersion(5)
    ErrorCorrectionLevel = ErrorCorrectionLevel.M
};
var qrCode = QrCode.Create("Hello, World!", qrCodeEncodingOptions);

Encode binary data

var qrCode = QrCode.Create([0xFE, 0xED, 0xCA, 0xFE]);

ECI support

// 26 is the ECI code for UTF-8
var eciCode = new EciCode(26);
var data = Encoding.UTF8.GetBytes("Hello, World!");
var qrCodeEncodingOptions = new QrCodeEncodingOptions
{
    ErrorCorrectionLevel = ErrorCorrectionLevel.M
    EciCode = eciCode
};
var qrCode = QrCode.Create(data, qrCodeEncodingOptions);

Advanced Usage

The entire toolset used to encode a QR Code is exposed publicly. This allows for more advanced use cases, for example, choosing a specific mask level or inspecting parts of the QR Code creation process.

For example, encoding a QR code using a specific mask pattern:

using System.Text;
using Quarer;

var str = "ABC123";
var data = Encoding.Latin1.GetBytes(str);
var errorCorrectionLevel = ErrorCorrectionLevel.M;
var eciCode = EciCode.Empty;
var analysisResult = QrDataEncoder.AnalyzeSimple(, errorCorrectionLevel, eciCode);
if (!analysisResult.Success)
{
    throw new InvalidOperationException("Data too large to fit into QR code.");
}

var maskPattern = MaskPattern.PatternThree_DiagonalLines;
var qrCodeEncodingInfo = analysisResult.Value;
var dataCodewords = QrDataEncoder.EncodeDataBits(qrCodeEncodingInfo, data);
var withErrorCodewords = QrDataEncoder.EncodeAndInterleaveErrorCorrectionBlocks(dataCodewords, qrCodeEncodingInfo.Version, qrCodeEncodingInfo.ErrorCorrectionLevel);
// passing in a specific mask pattern here skips all the mask pattern analysis logic
var (matrix, _) = QrSymbolBuilder.BuildSymbol(withErrorCodewords, qrCodeEncodingInfo.Version, qrCodeEncodingInfo.ErrorCorrectionLevel, maskPattern);
// matrix contains the complete QR code.

Roadmap

• Micro QR Codes
• rMQR Codes
• QR code Decoding