unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Timer1: TTimer;
    XPManifest1: TXPManifest;
    procedure Romb(x,y:integer; kx,ky:real);
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Timer1Timer(Sender: TObject);
    procedure Button3Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation
const x1 = 100; y1 = 300;
      x2 = 300; y2 = 300;

      dx = 20;
      dy = 40;

var x,y:integer;
    r:real  = 30.0;
    kx:real = 1.0;
    ky:real = 1.0;
    a:real  = 0;

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
timer1.interval := 50;
timer1.enabled  := false;
Form1.color     := clwhite;
end;

procedure TForm1.Romb(x,y:integer; kx,ky:real);
var xx, yy : integer;
begin
 xx := round( dx * kx );
 yy := round( dy * ky );

 canvas.MoveTo(x-xx, y);
 canvas.LineTo(x, y+yy);
 canvas.LineTo(x+xx, y);
 canvas.LineTo(x, y-yy);
 canvas.LineTo(x-xx, y);
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
canvas.FillRect(canvas.ClipRect);
Romb(x1, y1, 1, 1);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
kx := 1.0;
ky := 1.0;
a  := 0.0;
canvas.FillRect(canvas.ClipRect);
Timer1.Enabled := true;
end;

procedure TForm1.Timer1Timer(Sender: TObject);
begin
kx := kx*0.999;
ky := ky*0.999;

x := x2+round(r*cos(a));
y := y2+round(r*sin(a));
canvas.pen.color := clwhite;
canvas.pen.Width := 3;
Romb(x, y, kx, ky);

a := a+0.1;

x := x2+round(r*cos(a));
y := y2+round(r*sin(a));
canvas.pen.Width := 1;
canvas.pen.color := clblack;
Romb(x, y, kx, ky);

end;

procedure TForm1.Button3Click(Sender: TObject);
begin
close;
end;

end.