在ArcEngine中创建内存图层[转]

2008-04-29 10:43       

arcEngine9.2中新增了一个新的特征，允许创建内存工作空间。当你需要一个这样的图层时,这个图层的属性数据或者几何数据需要频繁的更新，而又不希望因此而带来效率上的问题，你就可以考虑使用内存图层。
        内存图层的创建分为五步：
      1、设置属性字段
      2、设置空间参考和几何字段
      3、创建内存工作空间
      4、在内存工作空间中创建特征类
      5、创建特征图层，并将上一步创建的特征类设置为这个特征的图层的特征类

请看以下完整的示例代码

        /// <summary>
        /// 在内存中创建图层
        /// </summary>
        /// <param name="DataSetName">数据集名称</param>
        /// <param name="AliaseName">别名</param>
        /// <param name="SpatialRef">空间参考</param>
        /// <param name="GeometryType">几何类型</param>
        /// <param name="PropertyFields">属性字段集合</param>
        /// <returns>IfeatureLayer</returns>
        public static IFeatureLayer CreateFeatureLayerInmemeory(string DataSetName, string AliaseName, ISpatialReference SpatialRef, esriGeometryType GeometryType, IFields PropertyFields)
        {
            IWorkspaceFactory workspaceFactory = new InMemoryWorkspaceFactoryClass();
            ESRI.ArcGIS.Geodatabase.IWorkspaceName workspaceName = workspaceFactory.Create("", "MyWorkspace", null, 0);
            ESRI.ArcGIS.esriSystem.IName name = (IName)workspaceName;
            ESRI.ArcGIS.Geodatabase.IWorkspace inmemWor = (IWorkspace)name.Open();

            IField oField = new FieldClass();
            IFields oFields = new FieldsClass();
            IFieldsEdit oFieldsEdit = null;
            IFieldEdit oFieldEdit = null;
            IFeatureClass oFeatureClass = null;
            IFeatureLayer oFeatureLayer = null;

            try
            {
                oFieldsEdit = oFields as IFieldsEdit;
                oFieldEdit = oField as IFieldEdit;

                for (int i = 0; i < PropertyFields.FieldCount; i++)
                {
                    oFieldsEdit.AddField(PropertyFields.get_Field(i));
                }

                IGeometryDef geometryDef = new GeometryDefClass();
                IGeometryDefEdit geometryDefEdit = (IGeometryDefEdit)geometryDef;
                geometryDefEdit.AvgNumPoints_2 = 5;
                geometryDefEdit.GeometryType_2 = GeometryType;
                geometryDefEdit.GridCount_2 = 1;
                geometryDefEdit.HasM_2 = false;
                geometryDefEdit.HasZ_2 = false;
                geometryDefEdit.SpatialReference_2 = SpatialRef;

                oFieldEdit.Name_2 = "SHAPE";
                oFieldEdit.Type_2 = esriFieldType.esriFieldTypeGeometry;
                oFieldEdit.GeometryDef_2 = geometryDef;
                oFieldEdit.IsNullable_2 = true;
                oFieldEdit.Required_2 = true;
                oFieldsEdit.AddField(oField);

                oFeatureClass = (inmemWor as IFeatureWorkspace).CreateFeatureClass(DataSetName, oFields, null, null, esriFeatureType.esriFTSimple, "SHAPE", "");
                (oFeatureClass as IDataset).BrowseName = DataSetName;

                oFeatureLayer = new FeatureLayerClass();
                oFeatureLayer.Name = AliaseName;
                oFeatureLayer.FeatureClass = oFeatureClass;
            }
            catch
            {
            }
            finally
            {
                try
                {
                    System.Runtime.InteropServices.Marshal.ReleaseComObject(oField);
                    System.Runtime.InteropServices.Marshal.ReleaseComObject(oFields);
                    System.Runtime.InteropServices.Marshal.ReleaseComObject(oFieldsEdit);
                    System.Runtime.InteropServices.Marshal.ReleaseComObject(oFieldEdit);
                    System.Runtime.InteropServices.Marshal.ReleaseComObject(name);
                    System.Runtime.InteropServices.Marshal.ReleaseComObject(workspaceFactory);
                    System.Runtime.InteropServices.Marshal.ReleaseComObject(workspaceName);
                    System.Runtime.InteropServices.Marshal.ReleaseComObject(inmemWor);
                    System.Runtime.InteropServices.Marshal.ReleaseComObject(oFeatureClass);
                }
                catch { }

                GC.Collect();
            }
            return oFeatureLayer;
        }

      返回来的这个特征图层就是我们所需要的结果，操作这个内存图层方式和操作物理图层方式完全一样。接下要做的事情就不必我说了吧。