QuickReport 3.0的导出文件 *.qrp 如何用代码的方式保存成图片格式

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procedure TForm1.Button1Click(Sender: TObject);
var
  APage : TMetafile;
begin
  if OpenDialog1.Execute then
  begin
    QRPreview1.QRPrinter:= TQRPrinter.Create(nil);
    QRPreview1.QRPrinter.Load(OpenDialog1.FileName);
    QRPreview1.Zoom:=100;
    //QRPreview1.PreviewImage.Show;//.QRPrinter.Preview;
    APage := QRPreview1.QRPrinter.GetPage(1);
    Image1.Width:=QRPreview1.PreviewImage.Width;
    Image1.Height:=QRPreview1.PreviewImage.Height;
    Image1.Canvas.StretchDraw(Rect(0,0,QRPreview1.PreviewImage.Width,QRPreview1.PreviewImage.Height), APage);
    Image1.Picture.SaveToFile(OpenDialog1.FileName+'.bmp');
    APage.Free;
  end;
end;