How to rescale PKDrawing in SwiftUI on screen rotation?

Im currently making an app usig PencilKit and SwiftUI. If the screen is rotated, the canvas (and the drawing) should be rescaled acordingly. I do this with the Geometry reader and calculating the size.

    NavigationView {
                GeometryReader { g in
                   HStack {
                    CanvasView(canvasView: $canvasView)
                        .frame(width: g.size.width/1.5, height: (g.size.width/1.5)/1.5)
                    placeholder(placeholder: scaleDrawing(canvasHeight: (g.size.width/1.5)/1.5))
                   }
                 }
    }


func scaleDrawing(canvasHeight : CGFloat) ->  Bool {
    
    let factor = canvasHeight / lastCanvasHeight

    let transform = CGAffineTransform(scaleX: factor, y: factor)
    
    canvasView.drawing = canvasView.drawing.transformed(using: transform)
    
    lastCanvasHeight = canvasHeight

    return true
}

The drawing however gets not scaled.
My solution was to create a placeholder view which has a boolean as a parameter. Also a method that scales the drawing with the height of the Canvas as an input.
This works but i think its pretty hacky and not the best solution, but this was the only solution that worked.
Is there a better way to do this? What am i missing?