GSS2Rework/GSS2.UI.Core/OpenCvImage.cs

using Avalonia;
using Avalonia.Media.Imaging;

using Mat = OpenCvSharp.Mat;
using Cv2 = OpenCvSharp.Cv2;

namespace GSS2.UI.Core;

public class OpenCvImage : ZoomPanImage
{
    private class OpenCvBitmap : Bitmap
    {
        public OpenCvBitmap(Mat mat)
        : base(
            format: Avalonia.Platform.PixelFormat.Rgba8888,
            alphaFormat: Avalonia.Platform.AlphaFormat.Unpremul,
            data: mat.Data,
            size: new PixelSize(mat.Width, mat.Height),
            dpi: new Vector(96, 96),
            stride: (mat.DataEnd - mat.DataStart).ToInt32() / mat.Rows
        )
        { }
    }

    public static readonly StyledProperty<Mat?> ImageProperty = AvaloniaProperty.Register<OpenCvImage, Mat?>(nameof(Image), defaultValue: null);
    public Mat? Image
    {
        get => GetValue(ImageProperty);
        set => SetValue(ImageProperty, value);
    }

    public OpenCvImage()
    : base()
    { }

    protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
    {
        if (change.Property == ImageProperty)
        {
            if (Image is null)
                return;

            if (Image.Type() != OpenCvSharp.MatType.CV_8UC3 &&
                Image.Type() != OpenCvSharp.MatType.CV_8UC4 &&
                Image.Type() != OpenCvSharp.MatType.CV_16UC3 &&
                Image.Type() != OpenCvSharp.MatType.CV_16UC4)
                return;

            var image = new Mat();
            Image.CopyTo(image);

            if (image.Type() == OpenCvSharp.MatType.CV_16UC3)
                image.ConvertTo(image, OpenCvSharp.MatType.CV_8UC3, 1 / 256.0);
            if (image.Type() == OpenCvSharp.MatType.CV_16UC4)
                image.ConvertTo(image, OpenCvSharp.MatType.CV_8UC4, 1 / 256.0);

            var channels = image.Split();
            var alphaChannel = image.Channels() == 4 ? channels[4] : new Mat(Image.Size(), OpenCvSharp.MatType.CV_8UC1, new OpenCvSharp.Scalar(255));
            Cv2.Merge([channels[2], channels[1], channels[0], alphaChannel], image);

            ImageSource = new OpenCvBitmap(image);

            InvalidateVisual();
        }
        base.OnPropertyChanged(change);
    }
}