Program.cs

using System;
using System.Drawing.Imaging;
using System.IO;
using System.Text;
using System.Windows.Markup;
using NDesk.Options;
using QRCoder;
using QRCoderConsole.DataObjects;

namespace QRCoderConsole;

#if NET6_0_WINDOWS
[System.Runtime.Versioning.SupportedOSPlatform("windows")]
#endif
internal class MainClass
{
    public static void Main(string[] args)
    {
        var friendlyName = AppDomain.CurrentDomain.FriendlyName;
        var newLine = Environment.NewLine;
        var setter = new OptionSetter();

        string fileName = null, outputFileName = null, payload = null;

        var eccLevel = QRCodeGenerator.ECCLevel.L;
        var imageFormat = SupportedImageFormat.Png;

        int pixelsPerModule = 20;
        string foregroundColor = "#000000";
        string backgroundColor = "#FFFFFF";


        var showHelp = false;

        var optionSet = new OptionSet {
            {    "e|ecc-level=",
                "error correction level",
                value => eccLevel = setter.GetECCLevel(value)
            },
            {   "f|output-format=",
                $"Image format for outputfile. Possible values: {string.Join(", ", Enum.GetNames(typeof(SupportedImageFormat)))} (default: png)",
                value => Enum.TryParse(value, true, out imageFormat)
            },
            {
                "i|in=",
                "input file | alternative to parameter -p",
                value => fileName = value
            },
            {
                "p|payload=",
                "payload string | alternative to parameter -i",
                value => payload = value
            },
            {
                "o|out=",
                "output file",
                value => outputFileName = value
            },
            {     "s|pixel=",
                "pixels per module",
                value => {
                             if (int.TryParse(value, out pixelsPerModule))
                             {
                                 if (pixelsPerModule < 1)
                                 {
                                     pixelsPerModule = 20;
                                 }
                             }
                             else
                             {
                                 pixelsPerModule = 20;
                             }
                }
            },
            {     "l|background=",
                "background color",
                value => backgroundColor = value
            },
            {     "d|foreground=",
                "foreground color",
                value => foregroundColor = value
            },
            {     "h|help",
                "show this message and exit.",
                value => showHelp = value != null
            }

        };

        try
        {

            optionSet.Parse(args);

            if (showHelp)
            {
                ShowHelp(optionSet);
            }

            string text = null;
            if (fileName != null)
            {
                var fileInfo = new FileInfo(fileName);
                if (fileInfo.Exists)
                {
                    text = GetTextFromFile(fileInfo);
                }
                else
                {
                    Console.WriteLine($"{friendlyName}: {fileName}: No such file or directory");
                }
            }
            else if (payload != null)
            {
                text = payload;
            }
            else
            {
                var stdin = Console.OpenStandardInput();

                text = GetTextFromStream(stdin);
            }

            if (text != null)
            {
                GenerateQRCode(text, eccLevel, outputFileName, imageFormat, pixelsPerModule, foregroundColor, backgroundColor);
            }
        }
        catch (Exception oe)
        {
            Console.Error.WriteLine(
                $"{friendlyName}:{newLine}{oe.GetType().FullName}{newLine}{oe.Message}{newLine}{oe.StackTrace}{newLine}Try '{friendlyName} --help' for more information");
            Environment.Exit(-1);
        }
    }

    private static void GenerateQRCode(string payloadString, QRCodeGenerator.ECCLevel eccLevel, string outputFileName, SupportedImageFormat imgFormat, int pixelsPerModule, string foreground, string background)
    {
        using var generator = new QRCodeGenerator();
        using var data = generator.CreateQrCode(payloadString, eccLevel);
        switch (imgFormat)
        {
            case SupportedImageFormat.Png:
            case SupportedImageFormat.Jpg:
            case SupportedImageFormat.Gif:
            case SupportedImageFormat.Bmp:
            case SupportedImageFormat.Tiff:
                using (var code = new QRCode(data))
                {
                    using var bitmap = code.GetGraphic(pixelsPerModule, foreground, background, true);
                    var actualFormat = new OptionSetter().GetImageFormat(imgFormat.ToString());
                    bitmap.Save(outputFileName, actualFormat);
                }
                break;
            case SupportedImageFormat.Svg:
                using (var code = new SvgQRCode(data))
                {
                    var test = code.GetGraphic(pixelsPerModule, foreground, background, true);
                    using var f = File.CreateText(outputFileName);
                    f.Write(test);
                    f.Flush();
                }
                break;
#if NETFRAMEWORK || NET5_0_WINDOWS || NET6_0_WINDOWS
            case SupportedImageFormat.Xaml:
                using (var code = new QRCoder.Xaml.XamlQRCode(data))
                {
                    var test = XamlWriter.Save(code.GetGraphic(pixelsPerModule, foreground, background, true));
                    using var f = File.CreateText(outputFileName);
                    f.Write(test);
                    f.Flush();
                }
                break;
#endif
            case SupportedImageFormat.Ps:
            case SupportedImageFormat.Eps:
                using (var code = new PostscriptQRCode(data))
                {
                    var test = code.GetGraphic(pixelsPerModule, foreground, background, true,
                        imgFormat == SupportedImageFormat.Eps);
                    using var f = File.CreateText(outputFileName);
                    f.Write(test);
                    f.Flush();
                }
                break;
            default:
                throw new ArgumentOutOfRangeException(nameof(imgFormat), imgFormat, null);
        }
    }

    private static string GetTextFromFile(FileInfo fileInfo)
    {
        var buffer = new byte[fileInfo.Length];

        using (var fileStream = new FileStream(fileInfo.FullName, FileMode.Open))
        {
            fileStream.Read(buffer, 0, buffer.Length);
        }

        return Encoding.UTF8.GetString(buffer);
    }

    private static string GetTextFromStream(Stream stream)
    {
        var buffer = new byte[256];
        var bytesRead = 0;

        using var memoryStream = new MemoryStream();
        while ((bytesRead = stream.Read(buffer, 0, buffer.Length)) > 0)
        {
            memoryStream.Write(buffer, 0, bytesRead);
        }

        var text = Encoding.UTF8.GetString(memoryStream.ToArray());

        Console.WriteLine($"text retrieved from input stream: {text}");

        return text;
    }

    private static void ShowHelp(OptionSet optionSet)
    {
        optionSet.WriteOptionDescriptions(Console.Out);
        Environment.Exit(0);
    }
}

public class OptionSetter
{
    public QRCodeGenerator.ECCLevel GetECCLevel(string value)
    {

        Enum.TryParse(value, out QRCodeGenerator.ECCLevel level);

        return level;
    }

#if NET6_0_WINDOWS
    [System.Runtime.Versioning.SupportedOSPlatform("windows")]
#endif
    public ImageFormat GetImageFormat(string value) => value.ToLower() switch
    {
        "jpg" => ImageFormat.Jpeg,
        "jpeg" => ImageFormat.Jpeg,
        "gif" => ImageFormat.Gif,
        "bmp" => ImageFormat.Bmp,
        "tiff" => ImageFormat.Tiff,
        _ => ImageFormat.Png,
    };
}