testGlobalToLocal method
Implementation
dynamic testGlobalToLocal(double x, double y) {
  if (!isRendererAttached) {
    return { 'x': 0, 'y': 0 };
  }
  Offset offset = Offset(x, y);
  Offset result = renderBoxModel!.globalToLocal(offset);
  return {'x': result.dx, 'y': result.dy};
}