IFeatureClass 与 IEnvelope 的转换

                ESRI.ArcGIS.Geodatabase.IFeatureClass fc = (editor.TargetLayer as ESRI.ArcGIS.Carto.IFeatureLayer).FeatureClass;
                IEnvelope pEnvelope = new EnvelopeClass();
                pEnvelope.SpatialReference = (fc as IGeoDataset).SpatialReference;