Engine 实现要素选取的方法(转载)
选择一个要素或者一个要素集（FeatureSelection）的方法很多，如IMap：：SelectByShape、ILayer：：search、IFeatureSection：：SelectFeature等方法
主要用到的方法：
IMap接口的SelectFeature(Layer, Feature) （方法，从一个Layer中选择一个Feature）；
IMap接口SelectByShape(Shape, env, justOne) （方法，从Layer中依靠一个图形的范围shape和一个选择的环境env来选择要素，而在所有图层中只从IFeatureLayer的图层中进行选择）
IFeatureSelection接口SelectFeatures (Filter, Method, justOne ) （方法，根据指定的标准过滤器filter和方法，选择要素，第一个参数为QueryFilter类型的变量，第二个参数为esriSelectionResultEnum类型的变量，第三个参数为布尔型变量，通常为false）
IFeatureLayer接口Search (IqueryFilter, book ) （方法，创建一个游标去查询相应设置的过滤器的查询）
选择一个要素或者一个要素集（FeatureSelection）的方法很多，如IMap：：SelectByShape、ILayer：：search、IFeatureSection：：SelectFeature等方法
主要用到的方法：
IMap接口的SelectFeature(Layer, Feature) （方法，从一个Layer中选择一个Feature）；
IMap接口SelectByShape(Shape, env, justOne) （方法，从Layer中依靠一个图形的范围shape和一个选择的环境env来选择要素，而在所有图层中只从IFeatureLayer的图层中进行选择）
IFeatureSelection接口SelectFeatures (Filter, Method, justOne ) （方法，根据指定的标准过滤器filter和方法，选择要素，第一个参数为QueryFilter类型的变量，第二个参数为esriSelectionResultEnum类型的变量，第三个参数为布尔型变量，通常为false）
IFeatureLayer接口Search (IqueryFilter, book ) （方法，创建一个游标去查询相应设置的过滤器的查询）
1 点选法获取要素
废话少说先看代码：
{
// Uses the ratio of the size of the map in pixels to map units to do the conversion
IPoint p1 = pActiveView.ScreenDisplay.DisplayTransformation.VisibleBounds.UpperLeft;
IPoint p2 = pActiveView.ScreenDisplay.DisplayTransformation.VisibleBounds.UpperRight;
int x1, x2, y1, y2;
pActiveView.ScreenDisplay.DisplayTransformation.FromMapPoint(p1, out x1, out y1);
pActiveView.ScreenDisplay.DisplayTransformation.FromMapPoint(p2, out x2, out y2);
double pixelExtent = x2 - x1;
double realWorldDisplayExtent = pActiveView.ScreenDisplay.DisplayTransformation.VisibleBounds.Width;
double sizeOfOnePixel = realWorldDisplayExtent / pixelExtent;
return pixelUnits * sizeOfOnePixel;
}
IMap pMap = axMapControl1.Map;
IActiveView pActiveView = pMap as IActiveView;
IFeatureLayer pFeatureLayer = pMap.get_Layer(0) as IFeatureLayer;
IFeatureClass pFeatureClass = pFeatureLayer.FeatureClass;
//设置点击点的位置
IPoint point = pActiveView.ScreenDisplay.DisplayTransformation.ToMapPoint(e.x, e.y);
ITopologicalOperator pTOpo = point as ITopologicalOperator;
double length;
length = ConvertPixelsToMapUnits(pActiveView, 4 );
IGeometry pBuffer = pTOpo.Buffer(length);
IGeometry pGeomentry = pBuffer.Envelope;
//空间滤过器
ISpatialFilter pSpatialFilter = new SpatialFilterClass();
pSpatialFilter.Geometry = pGeomentry;
//根据被选择要素的不同，设置不同的空间滤过关系
switch (pFeatureClass.ShapeType)
{
case esriGeometryType.esriGeometryPoint:
pSpatialFilter.SpatialRel= esriSpatialRelEnum.esriSpatialRelContains;
break ;
case esriGeometryType.esriGeometryPolyline:
pSpatialFilter.SpatialRel= esriSpatialRelEnum.esriSpatialRelCrosses;
break ;
case esriGeometryType.esriGeometryPolygon :
pSpatialFilter.SpatialRel= esriSpatialRelEnum.esriSpatialRelIntersects;
break ;
}
IFeatureSelection pFSelection=pFeatureLayer as IFeatureSelection;
pFSelection.SelectFeatures(pSpatialFilter,esriSelectionResultEnum.esriSelectionResultNew,false );
ISelectionSet pSelectionset= pFSelection.SelectionSet;
ICursor pCursor;
pSelectionset.Search(null,true,out pCursor);
IFeatureCursor pFeatCursor=pCursor as IFeatureCursor;
IFeature pFeature= pFeatCursor.NextFeature();
while(pFeature!=null )
{
pMap.SelectFeature(pFeatureLayer,pFeature);
pFeature= pFeatCursor.NextFeature();
}
pActiveView.PartialRefresh(esriViewDrawPhase.esriViewGraphicSelection,null,null );
//另外的改写：
pSpatialFilter.GeometryField = pFeatureClass.ShapeFieldName;
IQueryFilter pFilter = pSpatialFilter;
IFeatureCursor pFeatCursor = pFeatureLayer.Search(pFilter,false );
IFeature pFeature= pFeatCursor.NextFeature();
while(pFeature!=null )
{
pMap.SelectFeature(pFeatureLayer,pFeature);
pFeature= pFeatCursor.NextFeature();
}
pActiveView.PartialRefresh(esriViewDrawPhase.esriViewGraphicSelection,null,null);
另外还有一种比较简单的点选方法：
IGeometry g = null;
IEnvelope pEnv;
IActiveView pActiveView = axMapControl1.ActiveView;
IMap pMap = axMapControl1.Map;
pEnv = axMapControl1.TrackRectangle();
if (pEnv.IsEmpty == true)
{
ESRI.ArcGIS.Display.tagRECT r;
r.bottom = e.y + 5;
r.top = e.y - 5;
r.left = e.x - 5;
r.right = e.x + 5;
pActiveView.ScreenDisplay.DisplayTransformation.TransformRect(pEnv, ref r, 4);
pEnv.SpatialReference = pActiveView.FocusMap.SpatialReference;
}
g = pEnv as IGeometry;
axMapControl1.Map.SelectByShape(g, null, false);
axMapControl1.Refresh(esriViewDrawPhase.esriViewGeoSelection, null, null);
2 拉框选择
IMap pMap = axMapControl1.Map;
IActiveView pActiveView = pMap as IActiveView;
IEnvelope pEnv = axMapControl1.TrackRectangle();
pMap.SelectByShape(pEnv, null, false);
pActiveView.PartialRefresh(esriViewDrawPhase.esriViewGeoSelection,null, null);