Copyright (C) 1992, Digital Equipment Corporation                         
 All rights reserved.                                                      
 See the file COPYRIGHT for a full description.                            
 PathPrivate.def, by Mark Kent Fri Feb 20 22:10:03 1987 
 Last modified on Fri Apr  1 15:09:15 PST 1994 by heydon  
      modified on Tue Feb 11 16:22:28 PST 1992 by muller  
      modified on Wed Sep  4 19:22:22 PDT 1991 by gnelson 
      modified on Mon Aug  3 13:06:30 1987 by mkent 
This interface defines the representation of a Path.T.

INTERFACE PathPrivate;

IMPORT Point, Path, Word;

  ArrayRef = REF ARRAY OF Word.T;

    points: ArrayRef := NIL; (* data for the path *)
    start, next, current, end: ADDRESS := NIL;
    curveCount: CARDINAL := 0
The current data for the path is packed in [start^^), and the space [next^..end^) is available for additional segments.

If points # NIL, then the space between start and end is contained in the array points^. If points = NIL, then the path is read-only.

The value of current is the record for the MoveTo that started the last subpath, if it is open, and equal to next otherwise.

The value curveCount is the number of Bezier curves on the path.


PROCEDURE Freeze(path: Path.T): Lock;
PROCEDURE Thaw(l: Lock);
To read the address fields of a path, you must first call Freeze, preventing the allocator from moving the data in points. You must then call Thaw, passing the result of the call to Freeze when you no longer need the pointers to be maintained correctly.

  Type = {Curve, Line, Move, Close};
  Ttype = BITS Word.Size FOR Type;
  PCurve = UNTRACED REF CurveRec;
  CurveRec = RECORD ct: Ttype; p, q, r: Point.T; END;
  PLine = UNTRACED REF LineRec;
  LineRec = RECORD ct: Ttype; p: Point.T END;

  (* in a "PCurve", the "ct" field is "Curve".  in a "PLIne", the "ct"
     field is either Line, Move, or Close.   If "ct" is "Close",
     then "p" is the startpoint of the subpath that it closes.  *)

END PathPrivate.