This module maintains the virtual screen structures.

INTERFACE VTVirtual;

IMPORT Rd, Thread;
IMPORT VTDef;

TYPE
  T = VTDef.T;
  View = VTDef.View;
  I = VTDef.I;

PROCEDURE Change (vt: T; begin, oEnd, nEnd: I) RAISES {Rd.EndOfFile, Rd.Failure, Thread.Alerted};

PROCEDURE SetStart (view : View;
                    from : I;
                    n    : CARDINAL := 0;
                    force: BOOLEAN  := FALSE)
  RAISES {Rd.EndOfFile, Rd.Failure, Thread.Alerted};

PROCEDURE Update (vt: T) RAISES {Rd.EndOfFile, Rd.Failure, Thread.Alerted};

PROCEDURE UpdateView (view: View) RAISES {Rd.EndOfFile, Rd.Failure, Thread.Alerted};

PROCEDURE Init (view: View; start: I) RAISES {Rd.EndOfFile, Rd.Failure, Thread.Alerted};

PROCEDURE Bad (view: View) RAISES {Rd.EndOfFile, Rd.Failure, Thread.Alerted};

PROCEDURE Resize (view: View; n: CARDINAL) RAISES {};

END VTVirtual.