带透明度的位图

带代码

procedure TForm2.Button1Click(Sender: TObject);
var
  oMeta: TMetaFile;
  oBmp: TBitmap;
begin
  Image1.Transparent := True;
  Image1.Picture.LoadFromFile('D:\data\WMF.wmf');

  oBmp := TBitmap.Create;
  try
    oMeta := TMetaFile(Image1.Picture.Graphic);
    oBmp.SetSize(oMeta.Width, oMeta.Height);
    oBmp.Canvas.Draw(0, 0, oMeta);
    oBmp.SaveToFile('D:\data\WMF.bmp');
  finally
    oBmp.Free;
  end;
end;

procedure TForm2.Button2Click(Sender: TObject);
begin
  Image1.Transparent := True;
  Image1.Picture.LoadFromFile('D:\data\WMF.bmp');
end;

但图像显示时没有透明度。什么?如何以透明方式显示此bmp图像?

敬礼