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;
}
}
}