delphi 创建异形窗口[2]

unit Unit1;
interface
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;
type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure FormDblClick(Sender: TObject);
  end;
var
  Form1: TForm1;
implementation
{$R *.dfm}
procedure TForm1.FormCreate(Sender: TObject);
begin
  Button1.Caption := '创建';
end;
procedure TForm1.Button1Click(Sender: TObject);
const
  pts: array[0..3] of TPoint = (
    (x:10; y:40),
    (x:46; y:120),
    (x:82; y:40),
    (x:46; y:10)
  );
var
  rgn: HRGN;
begin
  rgn := CreatePolygonRgn(pts, Length(pts), 1); {1:ALTERNATE; 2:WINDING}
  SetWindowRgn(Handle, rgn, True);
end;
procedure TForm1.FormDblClick(Sender: TObject);
begin
  Close;
end;
end.