source: josm/src/org/openstreetmap/josm/data/osm/visitor/BoundingXYVisitor.java@ 159

package org.openstreetmap.josm.data.osm.visitor;

import org.openstreetmap.josm.Main;
import org.openstreetmap.josm.data.Bounds;
import org.openstreetmap.josm.data.coor.EastNorth;
import org.openstreetmap.josm.data.osm.Segment;
import org.openstreetmap.josm.data.osm.Node;
import org.openstreetmap.josm.data.osm.Way;

/**
 * Calculates the total bounding rectangle of a serie of OsmPrimitives, using the 
 * EastNorth values as reference.
 * @author imi
 */
public class BoundingXYVisitor implements Visitor {

        public EastNorth min, max;

        public void visit(Node n) {
                visit(n.eastNorth);
        }

        public void visit(Segment ls) {
                if (!ls.incomplete) {
                        visit(ls.from);
                        visit(ls.to);
                }
        }

        public void visit(Way w) {
                for (Segment ls : w.segments)
                        visit(ls);
        }

        public void visit(EastNorth eastNorth) {
                if (eastNorth != null) {
                        if (min == null)
                                min = eastNorth;
                        else if (eastNorth.east() < min.east() || eastNorth.north() < min.north())
                                min = new EastNorth(Math.min(min.east(), eastNorth.east()), Math.min(min.north(), eastNorth.north()));
                        
                        if (max == null)
                                max = eastNorth;
                        else if (eastNorth.east() > max.east() || eastNorth.north() > max.north())
                                max = new EastNorth(Math.max(max.east(), eastNorth.east()), Math.max(max.north(), eastNorth.north()));
                }
        }

        /**
         * @return The bounding box or <code>null</code> if no coordinates have passed
         */
        public Bounds getBounds() {
                if (min == null || max == null)
                        return null;
                return new Bounds(Main.proj.eastNorth2latlon(min), Main.proj.eastNorth2latlon(max));
        }
}