delphi 从资源加载时如何使 TBitmap 透明

procedure TMovie.BitBtn1Click(Sender: TObject);

var

 BitMap1 : TBitMap;

begin

  BitMap1 := TBitMap.Create;

  try

    BitMap1.LoadFromResourceName(HInstance,'Bitmap_2');

    BitMap1.Transparent := TRUE;

    BitMap1.TransparentColor := clBlack;

    Star_2.Picture.Assign(Bitmap1);

  finally

    BitMap1.Free;

  end;

end;