private string LegItemOnCache(ref LegendItem li) { Size sz = li.GetLegendSymbolSize(); Bitmap b = new Bitmap(sz.Width+1, sz.Height+1); Graphics g = Graphics.FromImage(b); li.LegendSymbol_Painted(g,new Rectangle(0,0,sz.Width,sz.Height)); string name = Guid.NewGuid().ToString(); MemoryStream MS = new MemoryStream(); b.Save(MS, System.Drawing.Imaging.ImageFormat.Png); byte[] buffer = MS.ToArray(); HttpContext.Current.Cache.Insert(name, buffer, null, Cache.NoAbsoluteExpiration, TimeSpan.FromMinutes(15)); g.Dispose(); b.Dispose(); return name; }