/// <summary> /// This method returns a FeatureDataTable containing all the rows from the shapefile that intersect the testGeometry. /// The ShapeFile.ExecuteIntersectionQuery method only tests bounding boxes so we use the FilterDelegate property to add a true /// intersection test using NetTopologySuite /// </summary> /// <param name="pathToShapefile">The path to the shapefile</param> /// <param name="testGeometry">The geometry that we want to test against</param> /// <returns></returns> public FeatureDataTable GetIntersectingFeaturesUsingFilterDelegate(string pathToShapefile, SMGeometry testGeometry) { //create a new shapefile provider using (ShapeFile shapefile = new ShapeFile(pathToShapefile)) { //create an nts GeometryFactory GeometryFactory geometryFactory = new GeometryFactory(); //convert the testGeometry into the equivalent NTS geometry GeoAPI.Geometries.IGeometry testGeometryAsNtsGeom = GeometryConverter.ToNTSGeometry(testGeometry, geometryFactory); SMGeometry check = GeometryConverter.ToSharpMapGeometry(testGeometryAsNtsGeom); if (!check.Equals(testGeometry)) throw new ApplicationException("conversion error"); //set the shapefile providers' FilterDelegate property to a new anonymous method //this delegate method will be called for each potential row shapefile.FilterDelegate = delegate(FeatureDataRow featureDataRow) { //get the geometry from the featureDataRow SMGeometry rowGeometry = featureDataRow.Geometry; //convert it to the equivalent NTS geometry GeoAPI.Geometries.IGeometry compareGeometryAsNtsGeometry = GeometryConverter.ToNTSGeometry(rowGeometry, geometryFactory); //do the test. Note that the testGeometryAsNtsGeometry is available here because it is //declared in the same scope as the anonymous method. bool intersects = testGeometryAsNtsGeom.Intersects(compareGeometryAsNtsGeometry); //return the result return intersects; }; //create a new FeatureDataSet FeatureDataSet featureDataSet = new FeatureDataSet(); //open the shapefile shapefile.Open(); //call ExecuteIntersectionQuery. The FilterDelegate will be used to limit the result set shapefile.ExecuteIntersectionQuery(testGeometry, featureDataSet); //close the shapefile shapefile.Close(); //return the populated FeatureDataTable return featureDataSet.Tables[0]; } }
/// <summary> /// This method takes a pre-populated FeatureDataTable and removes rows that do not truly intersect testGeometry /// </summary> /// <param name="featureDataTable">The FeatureDataTable instance to filter</param> /// <param name="testGeometry">the geometry to compare against</param> public void PostFilterExistingFeatureDataTable(FeatureDataTable featureDataTable, SMGeometry testGeometry) { //first we create a new GeometryFactory. var geometryFactory = new GeometryFactory(); //then we convert the testGeometry into the equivalent NTS geometry GeoAPI.Geometries.IGeometry testGeometryAsNtsGeom = GeometryConverter.ToNTSGeometry(testGeometry, geometryFactory); //now we loop backwards through the FeatureDataTable for (int i = featureDataTable.Rows.Count - 1; i > -1; i--) { //we get each row FeatureDataRow featureDataRow = featureDataTable.Rows[i] as FeatureDataRow; //and get the rows' geometry SMGeometry compareGeometry = featureDataRow.Geometry; //convert the rows' geometry into the equivalent NTS geometry GeoAPI.Geometries.IGeometry compareGeometryAsNts = GeometryConverter.ToNTSGeometry(compareGeometry, geometryFactory); //now test for intesection (note other operations such as Contains, Within, Disjoint etc can all be done the same way) bool intersects = testGeometryAsNtsGeom.Intersects(compareGeometryAsNts); //if it doesn't intersect remove the row. if (!intersects) featureDataTable.Rows.RemoveAt(i); } }