p; private
    { Private declarations }
    rgn : HRGN;
    rect : TRect;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.DrawRndRectRegion(wnd : HWND; rect : TRect);
begin
  rgn := CreateRoundRectRgn(rect.left, rect.top, rect.right, rect.bottom, 30, 30);
  SetWindowRgn(wnd, rgn, TRUE);
end;

procedure TForm1.DrawEllipticRegion(wnd : HWND; rect : TRect);
begin
  rgn := CreateEllipticRgn(rect.left, rect.top, rect.right, rect.bottom);
  SetWindowRgn(wnd, rgn, TRUE);
end;

procedure TForm1.DrawPolygonRegion(wnd : HWND; rect : TRect; NumPoints : Integer; DoStarShape : Boolean);
const
  RadConvert = PI/180;
  Degrees    = 360;
  MaxLines   = 100;
var
  x, y,
  xCenter,
  yCenter,
  radius,
  pts,
  I       : Integer;
  angle,
  rotation: Extended;
  arPts   : Array[0..MaxLines] of TPoint;
begin

  xCenter := (rect.Right - rect.Left) div 2;
  yCenter := (rect.Bottom - rect.Top) div 2;
  if DoStarShape then
    begin
      rotation := Degrees/(2*NumPoints);
      pts := 2 * NumPoints;
    end
  else
    begin
      rotation := Degrees/NumPoints;             //get number of degrees to turn per point
      pts := NumPoints
    end;
  radius := yCenter;

{This loop defines the Cartesian points of the shape. Again, I''ve added 90 degrees to the rotation angle so the shapes will stand up rather than lie on their sides. Thanks again to Terry Smithwick and David Ullrich for their trig help on CompuServe.}
  for I := 0 to pts - 1 do begin
    if DoStarShape then
      if (I mod 2) = 0 then //which means that
        radius := Round(radius/2)
      else
        radius := yCenter;

    angle := ((I * rotation) + 90) * RadConvert;
    x := xCenter + Round(cos(angle) * radius);
    y := yCenter - Round(sin(angle) * radius);
    arPts[I].X := x;
    arPts[I].Y := y;
  end;

  rgn := CreatePolygonRgn(arPts, pts, WINDING);
  SetWindowRgn(wnd, rgn, TRUE);
end;


procedure TForm1.Button1Click(Sender: TObject);
begin
  DrawEllipticRegion(Form1.Handle, Form1.ClientRect);
end;

procedure TForm1.Button2Click(Sender: TObject);