unit gilbert_;

interface

uses
 Windows, Messages, SysUtils,
 Variants, Classes, Graphics,
 Controls, Forms, Dialogs, StdCtrls, ComCtrls;

type
 TForml = class(TForm)
 procedure FormPaint(Sender: TObject);
 private
 { Private declarations }
 public
 { Public declarations }
 end;

var
 Form1: TForm1;

implementation
{$R *.dfm}

var
 p: integer = 5; // порядок кривой
 u: integer = 7; // длина штриха

{ Кривую Гильберта можно получить путем
соединения элементов а,b,с и d.

Каждый элемент строит
соответствующая процедура. }

procedure a(i: integer; canvas: TCanvas); forward;
procedure b(i: integer; canvas: TCanvas); forward;
procedure с(i: integer; canvas: TCanvas); forward;
procedure d(i: integer; canvas: TCanvas); forward;

// Элементы кривой
procedure a(i: integer; canvas: TCanvas);
begin
 if i > 0 then
 begin
 d(i - l, canvas);
 canvas.LineTo(canvas.PenPos.X + u, canvas.PenPos.Y);
 a(i - l, canvas);
 canvas.LineTo(canvas.PenPos.X, canvas.PenPos.Y + u);
 a(i - l, canvas);
 canvas.LineTo(canvas.PenPos.X - u, canvas.PenPos.Y);
 с(i - 1, canvas);
 end;
end;

procedure b(i: integer; canvas: TCanvas);
begin
 if i > 0 then
 begin
 c(i - l, canvas);
 canvas.LineTo(canvas.PenPos.X - u, canvas.PenPos.Y);
 b(i - 1, canvas);
 canvas.LineTo(canvas.PenPos.X, canvas.PenPos.Y - u);
 b(i - l, canvas);
 canvas.LineTo(canvas.PenPos.X + u, canvas.PenPos.Y);
 d(i - l, canvas);
 end;
end;

procedure c(i: integer; canvas: TCanvas);
begin
 if i > 0 then
 begin
 b(i - 1, canvas);
 canvas.LineTo(canvas.PenPos.X, canvas.PenPos.Y - u);
 с(i - 1, canvas);
 canvas.LineTo(canvas.PenPos.X - u, canvas.PenPos.Y);
 c(i - 1, canvas);
 canvas.LineTo(canvas.PenPos.X, canvas.PenPos.Y + u);
 a(i - 1, canvas);
 end;
end;

procedure d(i: integer; canvas: TCanvas);
begin
 if i > 0 then
 begin
 a(i - 1, canvas);
 canvas.LineTo(canvas.PenPos.X, canvas.PenPos.Y + u);
 d(i - 1, canvas);
 canvas.LineTo(canvas.PenPos.X + u, canvas.PenPos.Y);
 d(i - 1, canvas);
 canvas.LineTo(canvas.PenPos.X, canvas.PenPos.Y - u);
 b(i - 1, canvas);
 end;
end;

procedure TForml.FormPaint(Sender: TObject);
begin
 Form1.Canvas.MoveTo(u, u);
 a(5, Form1.Canvas); // вычертить кривую Гильберта
end;

end.