How to get a form as bitmap and copy it into the clipboard/ save it to a file

procedure TForm1.Button1Click(Sender: TObject);
var
  imgWindow: TBitmap;
begin
  imgWindow := GetFormImage;
  try
    Clipboard.Assign(imgWindow);
  finally
    imgWindow.Free;
  end;
end;

// Save the bitmap to a file
// Das Bitmap in einer Datei speichern:

procedure TForm1.Button2Click(Sender: TObject);
var
  imgWindow: TBitmap;
begin
  imgWindow := TBitmap.Create;
  try
    imgWindow := Form1.GetFormImage;
    imgWindow.SaveToFile('c:\FormImage.bmp');
  finally
    imgWindow.Free;
  end;
end;