def setup( root ):
      '''Must be called before any of the methods are used to initialize
      the conversion constants.'''
      tkMath.PIXELS_PER_INCH  = root.winfo_fpixels( '1i' )
      tkMath.PIXELS_PER_CM    = root.winfo_fpixels( '1c' )
      tkMath.PIXELS_PER_MM    = root.winfo_fpixels( '1m' )
      tkMath.PIXELS_PER_POINT = root.winfo_fpixels( '1p' )
Must be called before any of the methods are used to initialize
      the conversion constants.
recipes/Python/552745_tkMath_convert_between_pixels_inches_cm/recipe-552745.py