AE二次开发中，过滤后的图层，实现缩放至图层效果

//featureClass是自己获取的featureClass，也可是sde中获取的。              
    public void FilterAndZoomToLayer(IFeatureClass featureClass)
          {
                    IFeatureLayer featureLayer = new FeatureLayerClass();
                    featureLayer.FeatureClass = featureClass;
                    IFeatureLayerDefinition featureLayerDefinition = featureLayer as IFeatureLayerDefinition;
                    //获取符合条件的图层要素
                    featureLayerDefinition.DefinitionExpression = "XZQDM like '" + xz_xzqdm + "%'";
                    IFeatureLayer newFeatureLayer = featureLayerDefinition.CreateSelectionLayer(featureClass.AliasName, false, null, featureLayerDefinition.DefinitionExpression);
                  
                     ILayer newLayer = newFeatureLayer as ILayer;
                     mcView.AddLayer(newLayer);
 
                    //实现过滤后的图层，缩放到图层
                    IEnvelope envelope = new EnvelopeClass();
                    ILayer layer = mcView.get_Layer(0);
                    IFeatureLayer featureLayer = layer as IFeatureLayer;
                    IQueryFilter queryFilter = new QueryFilterClass();
                    queryFilter.WhereClause = "";
                    IFeatureCursor featureCursor = featureLayer.FeatureClass.Search(queryFilter, true);
                    IFeature feature = featureCursor.NextFeature();
                    while (feature != null)
                    {
                        IGeometry geometry = feature.Shape;
                        IEnvelope featureExtent = geometry.Envelope;
                        envelope.Union(featureExtent);
                        System.Runtime.InteropServices.Marshal.ReleaseComObject(feature);
                        feature = featureCursor.NextFeature();
                    }
                    mcView.ActiveView.FullExtent  = envelope;
           }

  //上面方法对于数据量较少的矢量是可以接受的，但对于一个县或一个市的数据，则加载比较慢。
           //经过研究和尝试，整理了一种新的缩放至图层的方式，如下

              //实现过滤后的图层，缩放到图层  
            IEnvelope  pEnvelope = new EnvelopeClass();
             //关键代码，替换了要素遍历，提高效率
            IEnumGeometryBind enumGeometryBind = new EnumFeatureGeometryClass();
            enumGeometryBind.BindGeometrySource(null, pFeatureClassDLTB);
            IEnumGeometry enumGeometry = (IEnumGeometry)enumGeometryBind;
            IGeometryFactory geoFactory = new GeometryEnvironment() as IGeometryFactory;
            IGeometry geo = geoFactory.CreateGeometryFromEnumerator(enumGeometry);
            pEnvelope.Union(geo.Envelope);
            System.Runtime.InteropServices.Marshal.ReleaseComObject(geo);
            System.Runtime.InteropServices.Marshal.ReleaseComObject(geoFactory);
            System.Runtime.InteropServices.Marshal.ReleaseComObject(enumGeometry);
            mcView.ActiveView.FullExtent  = pEnvelope;

转自：http://blog.csdn.net/u011116642/article/details/12562929