ArcEngine创建缓冲区，并查询缓冲区内要素

实现功能：

1.获取鼠标选中的要素

2.对选中要素设置缓冲距离，在地图上显示缓冲区

3.进行缓冲区查询，获得缓冲区内的要素，并放入TreeList展示

        /// 

        /// 创建缓冲区
        /// 
        private void CreateBuffer()
        {
            ITopologicalOperator pTopo = null;
            IElement pElement = null;
            IGeometry pBuffer = null;
            IGeometry pGeo = null;
            ISelection pSelection = null;
            IEnumFeatureSetup pEnumFeatureSetup = null;
            IEnumFeature pEnumFeature = null;
            IFillSymbol pFillSymbol = null;
            IRgbColor pRgbColor = null;

            IFeature pFea = null;
            IFeature pFeature = null;
            IFeatureLayer pFeaLayer = null;
            IFeatureClass pFeaClass = null;
            IFeatureCursor pFeaCursor = null;

            ISpatialFilter pSpatialfilter = null;

            try
            {
                if (m_pMap != null)
                {
                    (m_pMap as IGraphicsContainer).DeleteAllElements();
                }

                ////    获得选中要素
                pSelection = m_pMap.FeatureSelection;
                pEnumFeatureSetup = pSelection as IEnumFeatureSetup;
                pEnumFeatureSetup.AllFields = true;

                pEnumFeature = pEnumFeatureSetup as IEnumFeature;
                pEnumFeature.Reset();
                pFea = pEnumFeature.Next();

                ////    遍历选中要素
                while (pFea != null)
                {
                    pGeo = pFea.ShapeCopy;
                    pTopo = pGeo as ITopologicalOperator;
                    pBuffer = pTopo.Buffer(m_dDistance);

                    pElement = new PolygonElementClass();
                    pElement.Geometry = pBuffer;

                    ////    设置缓冲区颜色
                    pFillSymbol = new SimpleFillSymbolClass();
                    pRgbColor = new RgbColorClass();
                    pRgbColor.Red = 255;
                    pRgbColor.Green = 255;
                    pRgbColor.Blue = 153;
                    pRgbColor.Transparency = 1;
                    pFillSymbol.Color = pRgbColor;
                    (pElement as IFillShapeElement).Symbol = pFillSymbol;
                    (m_pMap as IGraphicsContainer).AddElement(pElement, 0);

                    ////    设置空间过滤器
                    pSpatialfilter = new SpatialFilterClass();
                    pSpatialfilter.Geometry = pBuffer;

                    ////    遍历图层
                    for (int i = 0; i < m_pMap.LayerCount; i++)
                    {
                        pFeaLayer = m_pMap.get_Layer(i) as IFeatureLayer;
                        pFeaClass = pFeaLayer.FeatureClass;

                        switch (pFeaClass.ShapeType)
                        {
                            case esriGeometryType.esriGeometryPoint:
                                {
                                    pSpatialfilter.SpatialRel = esriSpatialRelEnum.esriSpatialRelContains;
                                    break;
                                }
                            case esriGeometryType.esriGeometryPolyline:
                                {
                                    pSpatialfilter.SpatialRel = esriSpatialRelEnum.esriSpatialRelContains;
                                    break;
                                }
                            case esriGeometryType.esriGeometryPolygon:
                                {
                                    pSpatialfilter.SpatialRel = esriSpatialRelEnum.esriSpatialRelContains;
                                    break;
                                }
                        }

                        pSpatialfilter.GeometryField = pFeaClass.ShapeFieldName;
                        pFeaCursor = pFeaClass.Search(pSpatialfilter, false);
                        pFeature = pFeaCursor.NextFeature();

                        TreeListNode tlNode = null;

                        ////    查询到的要素添加到TreeList
                        while (pFeature != null)
                        {
                            ////    添加图层节点到TreeList
                            bool bIsContainLayer = false;
                            foreach (TreeListNode node in tlResult.Nodes)
                            {
                                if (node.GetDisplayText(0).Equals(pFeaLayer.Name))
                                {
                                    tlNode = node;
                                    bIsContainLayer = true;
                                    break;
                                }
                            }
                            if (!bIsContainLayer)
                            {
                                tlNode = tlResult.AppendNode(new object[] { pFeaLayer.Name }, null);
                            }

                            ////    添加要素到图层节点下
                            bool bIsAdd = false;
                            foreach (TreeListNode childnode in tlNode.Nodes)
                            {
                                if (childnode.GetDisplayText(0).Equals(pFeature.OID.ToString()))
                                {
                                    bIsAdd = true;
                                    break;
                                }
                            }
                            if (!bIsAdd)
                            {
                                tlResult.AppendNode(new object[] { pFeature.OID, GtMap.GxAEHelper.Feature.GetValue(pFeature, "NAME") }, tlNode);
                            }

                            pFeature = pFeaCursor.NextFeature();
                        }
                    }

                    pFea = pEnumFeature.Next();
                }

                IActiveView pActiveView = m_pMap as IActiveView;
                pActiveView.Refresh();

            }
            catch (Exception ex)
            {

            }
        }