arcgis engine C#中在map上绘制矩形并裁切

            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.RubberEnvelopeClass();
            ESRI.ArcGIS.Geometry.IGeometry geometry = rubberBand.TrackNew(screenDisplay,
              symbol);
            screenDisplay.SetSymbol(symbol);
            screenDisplay.DrawRectangle(geometry as ESRI.ArcGIS.Geometry.IEnvelope);
            // Dynamic cast.
            screenDisplay.FinishDrawing();

            String tempDirName = @"E:tmptttbar";
            String tempFileName = Guid.NewGuid().ToString() + ".tif";
            String tempFullName = tempDirName + @"" + tempFileName;
            ILayer pLayer = axMapControl1.get_Layer(0);
            IRasterLayer rasterLayer = (IRasterLayer)pLayer;

            IRaster pRaster = rasterLayer.Raster;

            //Initialize the Clip tool class.
            Clip clip = new Clip();
            //Set the parameters.
            clip.in_raster = pRaster;
            clip.out_raster = tempFullName;

            //The clipping envelope.
            //Comment this line out if clipping with a given dataset.
            clip.rectangle = String.Format("{0} {1} {2} {3}", envelope.XMin, envelope.YMin, envelope.XMax, envelope.YMax);

            //Initialize the geoprocessor and execute the Clip tool.
            Geoprocessor geoprocessor = new Geoprocessor();
            object outRaster = geoprocessor.Execute(clip, null);