Canvas { context, size in
   // Calculate size and draw image
   let image = UIImage(named: "picturedog")!
   let width = size.width
   let height = image.size.height * width / image.size.width
   let imageFrame = CGRect(origin: .zero, size: CGSize(width: width, height: height))
   context.draw(Image(uiImage: image), in: imageFrame)

   // Show heat map
   if let heatMap = try? observations?.heatMap.cgImage {
      let map = UIImage(cgImage: heatMap)
      context.blendMode = .multiply
      context.draw(Image(uiImage: map), in: CGRect(origin: .zero, size: imageFrame.size))
   }
}