原文

 

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

private double ConvertPixelsToMapUnits(IActiveView pActiveView, double pixelUnits)        {// Uses the ratio of the size of the map in pixels to map units to do the conversionIPoint 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);