ArcEngine中创建内存图层、空间、属性查询
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。
//空间、属性查询
属性查询是在当前map的layer中获取符合条件的feature的集合，实现过程是获取featurelayer的featureclass。然后定义过滤条件。在featureclass中执行search函数。获取查询结果。主要代码：
ILayer layer = axMapControl1.get_Layer(0);
IFeatureLayer featureLayer = layer as IFeatureLayer;
//获取featureLayer的featureClass
IFeatureClass featureClass = featureLayer.FeatureClass;
IFeature feature = null;
IQueryFilter queryFilter = new QueryFilterClass();
IFeatureCursor featureCusor;
queryFilter.WhereClause = “name = ‘” + searchName + “‘”;
featureCusor = featureClass.Search(queryFilter, true);
//search的参数第一个为过滤条件，第二个为是否重复执行。
feature = featureCusor.NextFeature();
if (feature != null)
{
axMapControl1.Map.SelectFeature(axMapControl1.get_Layer(0), feature);
axMapControl1.Refresh(esriViewDrawPhase.esriViewGeoSelection, null, null);
}
空间查询实现起来比较简单，使用arcgis封装好的函数即可，主要是获取选取的geometry对象：
axMapControl1.MousePointer = ESRI.ArcGIS.Controls.esriControlsMousePointer.esriPointerCrosshair;
IGeometry geometry = null;
switch (actionFlag)
{
case flag.POINTSELECT://点选
ESRI.ArcGIS.Geometry.Point pt = new ESRI.ArcGIS.Geometry.Point();
pt.X = e.mapX;
pt.Y = e.mapY;
geometry = pt as IGeometry;
break;
case flag.CIRCLESELECT://圆选
geometry = axMapControl1.TrackCircle();
break;
case flag.RECTSELECT://长方形选取
geometry = axMapControl1.TrackRectangle();
break;
case flag.POLYGONSELECT://多边形选取
geometry = axMapControl1.TrackPolygon();
break;
}
axMapControl1.Map.SelectByShape(geometry, null, false);
axMapControl1.Refresh(esriViewDrawPhase.esriViewGeoSelection, null, null);
转载自：https://blog.csdn.net/wzcool273509239/article/details/17447621
