/// 
        /// 在MapControl上画多边形、面        /// 
        ///         public void DrawPolygon(ESRI.ArcGIS.Carto.IActiveView activeView)        {            if (activeView == null)            {                return;            }            ESRI.ArcGIS.Display.IScreenDisplay screenDisplay = activeView.ScreenDisplay;            // Constant            screenDisplay.StartDrawing(screenDisplay.hDC, (System.Int16)ESRI.ArcGIS.Display.esriScreenCache.esriNoScreenCache); // Explicit Cast            ESRI.ArcGIS.Display.IRgbColor rgbColor = new ESRI.ArcGIS.Display.RgbColorClass();            rgbColor.Red = 255;            ESRI.ArcGIS.Display.IColor color = rgbColor; // Implicit Cast            ESRI.ArcGIS.Display.ISimpleFillSymbol simpleFillSymbol = new ESRI.ArcGIS.Display.SimpleFillSymbolClass();            simpleFillSymbol.Color = color;            ESRI.ArcGIS.Display.ISymbol symbol = simpleFillSymbol as ESRI.ArcGIS.Display.ISymbol; // Dynamic Cast          //ESRI.ArcGIS.Display.IRubberBand rubberBand = new ESRI.ArcGIS.Display.RubberPolygonClass(); //多边形            ESRI.ArcGIS.Display.IRubberBand rubberBand = new ESRI.ArcGIS.Display.RubberLineClass(); //折线            ESRI.ArcGIS.Geometry.IGeometry geometry = rubberBand.TrackNew(screenDisplay, symbol);            screenDisplay.SetSymbol(symbol);          //screenDisplay.DrawPolygon(geometry);多边形            screenDisplay.DrawPolyline(geometry);            screenDisplay.FinishDrawing();        }        private void axMapControl1_OnMouseDown(object sender, ESRI.ArcGIS.Controls.IMapControlEvents2_OnMouseDownEvent e)        {            DrawPolygon(this.axMapControl1.ActiveView);        }