unit Unit1;

interface

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

type
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
bit: TBitmap;
begin
bit := TBitmap.Create;
bit.Width := Width;
bit.Height := Height;
BitBlt(bit.Canvas.Handle, 0, 0, Width, Height, GetWindowDC(Handle), 0, 0, SRCCOPY);
bit.SaveToFile('c:\temp\Form1.bmp');
bit.Free;
end;

end.