ArcgisEngine+C#开发中，对一个图层进行过滤，并只显示符合条件的要素

在二次开发中，经常会对一个图层进行查询，查询出符合条件的要素，我们通常会想到：

 IQueryFilter queryFilter = new QueryFilterClass();
queryFilter.WhereClause = "XZQDM =510113";

 IFeatureCursor featureCursor = sourceFeatureClass.Search(queryFilter, true);
                IFeature feature= featureCursor.NextFeature();
                while (feature!= null)       

                 {
                    System.Runtime.InteropServices.Marshal.ReleaseComObject(feature);
                    pFeature = featureCursor.NextFeature();
                }

 System.Runtime.InteropServices.Marshal.ReleaseComObject(featureCursor);

但是这种方法虽然可以找到我们希望得到的效果，但是不符合条件的要素依然显示。

 

其实有一种高效的方法，可以实现从一个图层查询，并只显示符合条件的要素：

其中featureLayer是进行查询的图层，"XZQDM =510113"是查询条件

 IFeatureLayerDefinition   featureLayerDefinition = featureLayer as IFeatureLayerDefinition;
 featureLayerDefinition.DefinitionExpression ="XZQDM =510113";

在使用地图模块动态开发，即地图图层的要素类动态从sde数据库中获取要素类时（大量空间数据存储在sde的要素类中），

此方法十分有效，前提是模板要素类的表结构和sde中的获取要素类表结构相同。

其中featureClass是从sde空间数据库中获取的要素类，

featureLayer.FeatureClass=featureClass;

IFeatureLayerDefinition   featureLayerDefinition = featureLayer as IFeatureLayerDefinition;
 featureLayerDefinition.DefinitionExpression ="XZQDM =510113";

 

 

关于IFeatureLayerDefinition

IFeatureLayerDefinition--自定义要素层接口

实现该接口的主要组件类(CoClass)--FeatureLayer

项目中使用该接口实现的方法：

将某个图层的选择集提取出来新建临时图层：

IFeatureLayer pFeatureLayer = _myMap.get_Layer(0) as IFeatureLayer;
 //MessageBox.Show(pFeatureLayer.Name+"1111");
 IFeatureSelection pFeatureSelection = pFeatureLayer as IFeatureSelection;
 ISelectionSet pSelectionSet = pFeatureSelection.SelectionSet;
 if (pSelectionSet == null)
 {
     System.Windows.Forms.MessageBox.Show("请选择一块图幅！");
 }
 IFeatureLayerDefinition pFeatureLayerDef = pFeatureLayer as IFeatureLayerDefinition;
 pFeatureLayerDef.CreateSelectionLayer("tempLayer", true, null, null);
 IFeatureLayer pTempFeatureLayer = pFeatureLayerDef as IFeatureLayer;

对图层的显示进行处理(屏蔽)：

  IFeatureLayer featureLayer = _myMap.Layer[0] as IFeatureLayer;
 IFeatureLayerDefinition featureLayerDefinition = featureLayer as IFeatureLayerDefinition;
 //只显示objectID = 657的要素，其他要素屏蔽掉
 featureLayerDefinition.DefinitionExpression = "OBJECTID = '657'";

 

转自：http://blog.csdn.net/u011116642/article/details/9355251