package com.vividsolutions.jts.operation.distance; import java.util.ArrayList; import java.util.Iterator; import java.util.List; import com.vividsolutions.jts.geom.CoordinateSequence; import com.vividsolutions.jts.geom.Geometry; import com.vividsolutions.jts.geom.GeometryComponentFilter; import com.vividsolutions.jts.geom.LineString; import com.vividsolutions.jts.geom.Point; import com.vividsolutions.jts.geom.util.LinearComponentExtracter; import com.vividsolutions.jts.index.strtree.STRtree; public class FacetSequenceTreeBuilder { // 6 seems to be a good facet sequence size private static final int FACET_SEQUENCE_SIZE = 6; // Seems to be better to use a minimum node capacity private static final int STR_TREE_NODE_CAPACITY = 4; public static STRtree build(Geometry g) { STRtree tree = new STRtree(STR_TREE_NODE_CAPACITY); List sections = computeFacetSequences(g); for (Iterator i = sections.iterator(); i.hasNext();) { FacetSequence section = (FacetSequence) i.next(); tree.insert(section.getEnvelope(), section); } tree.build(); return tree; } /** * Creates facet sequences * * @param g * @return List<GeometryFacetSequence> */ private static List computeFacetSequences(Geometry g) { final List sections = new ArrayList(); g.apply(new GeometryComponentFilter() { public void filter(Geometry geom) { CoordinateSequence seq = null; if (geom instanceof LineString) { seq = ((LineString) geom).getCoordinateSequence(); addFacetSequences(seq, sections); } else if (geom instanceof Point) { seq = ((Point) geom).getCoordinateSequence(); addFacetSequences(seq, sections); } } }); return sections; } private static void addFacetSequences(CoordinateSequence pts, List sections) { int i = 0; int size = pts.size(); while (i <= size - 1) { int end = i + FACET_SEQUENCE_SIZE + 1; // if only one point remains after this section, include it in this // section if (end >= size - 1) end = size; FacetSequence sect = new FacetSequence(pts, i, end); sections.add(sect); i = i + FACET_SEQUENCE_SIZE; } } }