photomator/Photomator/Lib.cs

using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Formats.Webp;
using SixLabors.ImageSharp.Processing;

namespace Photomator;

public static class Lib {
    public static async Task Convert(string src, string dest, ConvertOptions options) {
        Image img = await Image.LoadAsync(src);
        img.Mutate(i => {
            i.AutoOrient();
            Size currentSize = i.GetCurrentSize();
            if (currentSize.Height > currentSize.Width) {
                i.Resize(options.Resolution, 0);
            } else {
                i.Resize(0, options.Resolution);
            }
        });
        await img.SaveAsWebpAsync(dest, new WebpEncoder {
            FileFormat = options.Format
        });
    }

    public static async Task<ConvertError[]> ConvertList(string[] src, string dest, ConvertOptions options, Action<double> setProgress) {
        double progress = 0;
        List<ConvertError> unconverted = [];
        await Parallel.ForEachAsync(src, new ParallelOptions { MaxDegreeOfParallelism = Environment.ProcessorCount }, async (path, _) => {
            string filename = path.Split(Path.DirectorySeparatorChar)[^1];
            string[] splitted = filename.Split('.');
            splitted[^1] = "webp";
            try {
                await Convert(path, dest + Path.DirectorySeparatorChar + string.Join(".", splitted), options);
            } catch (UnknownImageFormatException) {
                unconverted.Add(new ConvertError(filename, "Das Dateiformat wird nicht unterstützt."));
            } catch (Exception e) {
                unconverted.Add(new ConvertError(filename, e.Message));
            }
            progress += 1.0 / src.Length;
            setProgress(progress);
        });
        return [.. unconverted];
    }
}

public readonly struct ConvertOptions(string? resolution, uint format) {
    public int Resolution { get; init; } = resolution != null ? Convert.ToInt32(resolution) : 1440;
    public WebpFileFormatType Format { get; init; } = format == 1 ? WebpFileFormatType.Lossless : WebpFileFormatType.Lossy;
}

public readonly struct ConvertError(string file, string message) {
    public string File { get; init; } = file;
    public string Message { get; init; } = message;
}