function WaterMark()
{
      if ( 0 == iWebPDF2015.Documents.Count )
      { alert("没有已打开文档");
            return;
      }
      var Watermark = iWebPDF2015.Documents.ActiveDocument.Watermark;
      Watermark.FontColor= "001";
      Watermark.FontSize = 80;
      Watermark.Opacity = 0.3;
      Watermark.Rotation = 30;
      Watermark.Text = "WaterMark";
      Watermark.Execute(0, 50, 400);
      Watermark.Execute(0, 50, 600);
      iWebPDF2015.Documents.ActiveDocument.Pages.Item(0).Refresh();
      iWebPDF2015.Documents.ActiveDocument.Views.ActiveView.Refresh();
}