INTERFACE TestDrawContext;
IMPORT DrawContext;
IMPORT BoundDrawContext;
TYPE
  T <: Public;
  Public = BoundDrawContext.T OBJECT
  METHODS
    init(dc: DrawContext.T): T;
    (* the idea is to decide if lines and text drawn in dc would be visible. *)

    reset();
    (* start accumulating visible status *)

    visible(): BOOLEAN;
    (* TRUE iff some line drawn since reset() would be visible in dc. *)
  END;
END TestDrawContext.