annotations/Azaion.Annotator/DTO/AnnotationInfo.cs

using System.Globalization;
using System.Windows;

namespace Azaion.Annotator.DTO;

public class AnnotationInfo
{
    public int ClassNumber { get; set; }
    public double X { get; set; }
    public double Y { get; set; }
    public double Width { get; set; }
    public double Height { get; set; }

    public AnnotationInfo() { }
    public AnnotationInfo(int classNumber, double x, double y, double width, double height)
    {
        ClassNumber = classNumber;
        X = x;
        Y = y;
        Width = width;
        Height = height;
    }

    public override string ToString() => string.Concat(ClassNumber.ToString(),
        " ",
        X.ToString("F5", CultureInfo.InvariantCulture),
        " ",
        Y.ToString("F5", CultureInfo.InvariantCulture),
        " ",
        Width.ToString("F5", CultureInfo.InvariantCulture),
        " ",
        Height.ToString("F5", CultureInfo.InvariantCulture));

    public AnnotationInfo ToLabelCoordinates(Size canvasSize, Size videoSize)
    {
        var cw = canvasSize.Width;
        var ch = canvasSize.Height;
        var canvasAR = cw / ch;
        var videoAR = videoSize.Width / videoSize.Height;

        var annInfo = new AnnotationInfo { ClassNumber = this.ClassNumber };
        double left, top;
        if (videoAR > canvasAR) //100% width
        {
            left = X / cw;
            annInfo.Width = Width / cw;
            var realHeight = cw / videoAR; //real video height in pixels on canvas
            var blackStripHeight = (ch - realHeight) / 2.0; //height of black strips at the top and bottom
            top = (Y - blackStripHeight) / realHeight;
            annInfo.Height = Height / realHeight;
        }
        else //100% height
        {
            top = Y / ch;
            annInfo.Height = Height / ch;
            var realWidth = ch * videoAR; //real video width in pixels on canvas
            var blackStripWidth = (cw - realWidth) / 2.0; //height of black strips at the top and bottom
            left = (X - blackStripWidth) / realWidth;
            annInfo.Width = Width / realWidth;
        }

        annInfo.X = left + annInfo.Width / 2.0;
        annInfo.Y = top + annInfo.Height / 2.0;
        
        return annInfo;
    }

    public AnnotationInfo ToCanvasCoordinates(Size canvasSize, Size videoSize)
    {
        var cw = canvasSize.Width;
        var ch = canvasSize.Height;
        var canvasAR = cw / ch;
        var videoAR = videoSize.Width / videoSize.Height;
        
        var annInfo = new AnnotationInfo { ClassNumber = this.ClassNumber };
        
        double left = X - Width / 2;
        double top = Y - Height / 2;
        
        if (videoAR > canvasAR) //100% width
        {
            var realHeight = cw / videoAR; //real video height in pixels on canvas
            var blackStripHeight = (ch - realHeight) / 2.0; //height of black strips at the top and bottom
            
            annInfo.X = left * cw;
            annInfo.Y = top * realHeight + blackStripHeight;
            annInfo.Width = Width * cw;
            annInfo.Height = Height * realHeight;
        }
        else //100% height
        {
            var realWidth = ch * videoAR; //real video width in pixels on canvas
            var blackStripWidth = (cw - realWidth) / 2.0; //height of black strips at the top and bottom

            annInfo.X = left * realWidth + blackStripWidth;
            annInfo.Y = top * ch;
            annInfo.Width = Width * realWidth;
            annInfo.Height = Height * ch;
        }
        return annInfo;
    }

    public static AnnotationInfo? Parse(string? s)
    {
        if (s == null || string.IsNullOrEmpty(s))
            return null;
        
        var strs = s.Replace(',','.').Split(' ');
        if (strs.Length != 5)
            return null;

        try
        {
            var res = new AnnotationInfo
            {
                ClassNumber = int.Parse(strs[0], CultureInfo.InvariantCulture),
                X = double.Parse(strs[1], CultureInfo.InvariantCulture),
                Y = double.Parse(strs[2], CultureInfo.InvariantCulture),
                Width = double.Parse(strs[3], CultureInfo.InvariantCulture),
                Height = double.Parse(strs[4], CultureInfo.InvariantCulture)
            };
            return res;
        }
        catch (Exception)
        {
            return null;
        }
    }
}