The TDrawEllipse structure

 // DrawEllipse
 TDrawEllipse   struct
  Result                sbyte     // The function call result. NO_ERR means it succeeded.
  Center                TLocation // The location on screen.
  SizeX         byte
  SizeY         byte
  Options           dword     // The options to use when writing to the LCD.
 TDrawEllipse   ends

See Drawing option constants for valid Options values.