(* Routines to generate Postscript files *)

INTERFACE PSPlot;

IMPORT Wr;

TYPE Axis = {X, Y};

PROCEDURE BeginFile (psfile: Wr.T);
  (* Initializes a plot set. *)

PROCEDURE BeginPage (
    psfile: Wr.T;
    page: CARDINAL;
    xmin, xmax: LONGREAL;
    ymin, ymax: LONGREAL;
    xn, yn: CARDINAL
  );
  (* Intializes a new page: writes page header line, *)
  (* sets coordinate system, clip path, caption font, *)
  (* defines new Postscript operators and constants, etc. *)
  (* The plotting area is divided implicitly into a grid *)
  (* of /xn/ by /yn/ rectangular "cells". *)

PROCEDURE BeginSection (psfile: Wr.T; title: TEXT);
  (* Starts a new section of a plot. The title is a comment *)

PROCEDURE SetPen (
    psfile: Wr.T;
    gray: REAL;
    width: REAL;
    dashlength: REAL;
    dashspace: REAL
  );
  (* Sets pen parameters and ink color for line drawing. *)
  (* Dimensions are in mm *)

PROCEDURE DrawSegment (psfile: Wr.T; xa, ya, xb, yb: LONGREAL);
  (* Draws segment from (xa,ya) to (xb,yb) with current pen and gray *)

PROCEDURE DrawRectangle (psfile: Wr.T; xlo, xhi, ylo, yhi: LONGREAL);
  (* Draws the outline of thegiven rectangle using the current pen. *)

PROCEDURE FillRectangle (
    psfile: Wr.T; 
    xlo, xhi, ylo, yhi: LONGREAL;
    gray: REAL
  );
  (* Fills given rectangle with given gray color *)

PROCEDURE FillAndDrawRectangle (
    psfile: Wr.T;
    xlo, xhi, ylo, yhi: LONGREAL;
    gray: REAL
  );
  (* Fills rectangle with given gray, then *)
  (* draws its outline with current pen. *)

PROCEDURE FillTriangle (
    psfile: Wr.T;
    xa, ya, xb, yb, xc, yc: LONGREAL;
    gray: REAL;
  );
  (* Fills triangle /abc/ with given gray level. *)

PROCEDURE FillCircle (
    psfile: Wr.T;
    xc, yc, radius: LONGREAL;
    gray: REAL
  );
  (* Fills the circle with given center and radius, using the given gray. *)
  
PROCEDURE DrawCircle (
    psfile: Wr.T;
    xc, yc, radius: LONGREAL;
  );
  (* Draws the circle with given center and radius, *)
  (* using the current pen and gray. *)
  
PROCEDURE FillAndDrawCircle (
    psfile: Wr.T;
    xc, yc, radius: LONGREAL;
    gray: REAL;
  );
  (* Fills the circle with given center and radius, *)
  (* using the given gray, then draws its outline, *)
  (* using the current pen and gray. *)

PROCEDURE FillGridCell (psfile: Wr.T; xi, yi: CARDINAL; gray: REAL);
  (* Fills the given cell of the current cell grid with *)
  (* the given gray level. *)

PROCEDURE DrawCoordLine (psfile: Wr.T; axis: Axis; coord: LONGREAL);
  (* Draws a reference line perpendicular to the given axis *)
  (* at the given coordinate value. *)

PROCEDURE DrawGridLines (psfile: Wr.T);
  (* Draws the grid lines with the current pen and gray level. *)

PROCEDURE EndSection (psfile: Wr.T);
  (* Ends a section of a plot. *)

PROCEDURE AddCaption (psfile: Wr.T; txt: TEXT);
  (* Appends a caption line under the drawing. *)
  (* For multi-line captions, use multiple calls *)
  (* and/or embedded newlines. *)

PROCEDURE DrawFrame (psfile: Wr.T);
  (* Draws a frame around the plotting area *)

PROCEDURE EndPage(psfile: Wr.T);
  (* Finalizes a page: Writes page trailer line, etc. *)

PROCEDURE EndFile (psfile: Wr.T; npages: CARDINAL := LAST(CARDINAL));
  (* Finalizes plot set. *)

END PSPlot.