WPF How do you get the correct canvas top and and left points to draw a circle at specific location on the image?

Question

I have an Image on a Canvas that is on a Boarder.
I want to draw a circle at specific location on the image. I am able to get this to work when I have the Image set to fill, but it is off when the Image is set to Uniform. I tried to make an offset by doing this:

    public BitmapImage  ImageSource
    {
        get => (BitmapImage)GetValue( ImageSourceProperty);

        set
        {
            if (_imageSource == value) return;
            _imageSource = value;
            SetValue( ImageSourceProperty, value);
            OnPropertyChanged();
        }

    }

  private Point GetCoordinates(double x, double y)
    {
        double sourceHeight = ImageSource.PixelHeight;
        double sourceWidth = ImageSource.PixelWidth;
        double DisplayHeight = Imagebox.Height;
        double DisplayWidth = Imagebox.Width;
        double Yoffset = Canvas.GetTop(Imagebox);
        double Xoffset = Canvas.GetLeft(Imagebox);

        double displayY = Yoffset- (DisplayHeight/ sourceHeight)  * y;
        double displayX = Xoffset- (DisplayWidth /sourceWidth) * x;
       
      
        Point coordinates = new Point(displayX, displayY);
        // Return the general transform for the specified visual object.
        GeneralTransform generalTransform1 = ImageBorder.TransformToVisual(Imagebox);
        // Retrieve the point value relative to the child.
        Point currentPoint = generalTransform1.Transform(coordinates);

        return currentPoint;
    }

but somehow xoffset and yoffset are alway NanA.

here is my XAML

 <Border x:Name="ImageBorder" ClipToBounds="True" Background="White">
    <Canvas x:Name="ImageCanvas"    >
        <Image x:Name="ImageBox"   RenderTransformOrigin="0.5,0.5"   Width="{Binding Path=ActualWidth, ElementName=ImageCanvas}" Height="{Binding Path=ActualHeight, ElementName=ImageCanvas}"      Stretch="Uniform" />
    </Canvas>
</Border>

How do you get the correct canvas top and and left points to draw a circle at specific location on the image?

UPDATE:

<Grid  x:Name="ImageBorder">
    <Image x:Name="ImageBox"   Stretch="Uniform" />
    <Canvas x:Name="ImageCanvas" />
</Grid>

    private Point GetCoordinates(double x, double y)
     {
     double sourceHeight = ImageSource.PixelHeight;
        double sourceWidth = ImageSource.PixelWidth;
        double DisplayHeight = ImageBorder.ActualHeight;
        double DisplayWidth = ImageBorder.ActualWidth;



        double displayY =  (DisplayHeight/ sourceHeight)  * y;
        double displayX = (DisplayWidth /sourceWidth) * x;
       
        Point coordinates = new Point(displayX, displayY);
       
        GeneralTransform generalTransform1 = ImageBorder.TransformToVisual(Imagebox);
        // Retrieve the point value relative to the child.
        Point currentPoint = generalTransform1.Transform(coordinates);

        return currentPoint;}