source: osm/utils/josm/plugins/osmarender/src/OsmarenderPlugin.java@ 1443

import static org.openstreetmap.josm.tools.I18n.tr;

import java.awt.event.ActionEvent;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Collection;
import java.util.HashSet;

import javax.swing.AbstractAction;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;

import org.openstreetmap.josm.Main;
import org.openstreetmap.josm.data.Bounds;
import org.openstreetmap.josm.data.coor.LatLon;
import org.openstreetmap.josm.data.osm.DataSet;
import org.openstreetmap.josm.data.osm.Node;
import org.openstreetmap.josm.data.osm.Segment;
import org.openstreetmap.josm.data.osm.Way;
import org.openstreetmap.josm.data.osm.visitor.AddVisitor;
import org.openstreetmap.josm.gui.MapFrame;
import org.openstreetmap.josm.io.OsmWriter;
import org.openstreetmap.josm.plugins.Plugin;


public class OsmarenderPlugin extends Plugin {

        private class Action extends AbstractAction {

                public Action() {
                        super("Osmarender");
                }

                public void actionPerformed(ActionEvent e) {
                        // get all stuff visible on screen
                        LatLon bottomLeft = Main.map.mapView.getLatLon(0,Main.map.mapView.getHeight());
                        LatLon topRight = Main.map.mapView.getLatLon(Main.map.mapView.getWidth(), 0);
                        Bounds b = new Bounds(bottomLeft, topRight);
                        Collection<Node> nodes = new HashSet<Node>();
                        DataSet fromDataSet = new DataSet();
                        AddVisitor adder = new AddVisitor(fromDataSet);
                        for (Node n : Main.ds.nodes) {
                                if (n.coor.isWithin(b)) {
                                        n.visit(adder);
                                        nodes.add(n);
                                }
                        }
                        Collection<Segment> segments = new HashSet<Segment>();
                        for (Segment s : Main.ds.segments) {
                                if (nodes.contains(s.from) || nodes.contains(s.to)) {
                                        s.visit(adder);
                                        segments.add(s);
                                }
                        }
                        for (Way w : Main.ds.ways) {
                                for (Segment s : w.segments) {
                                        if (segments.contains(s)) {
                                                w.visit(adder);
                                                break;
                                        }
                                }
                        }

                        try {
                                // store the stuff in data.osm
                                OsmWriter.output(new FileOutputStream(getPluginDir()+"data.osm"), new OsmWriter.All(fromDataSet, true));

                                // launch up the viewer
                                String firefox = Main.pref.get("osmarender.firefox", "firefox");
                                Runtime.getRuntime().exec(firefox+" "+getPluginDir()+"osm-map-features.xml");
                        } catch (IOException e1) {
                                JOptionPane.showMessageDialog(Main.parent, "Could not launch Osmarender.");
                        }
                }
        }

        private JMenu view;
        private JMenuItem osmarenderMenu = new JMenuItem(new Action());

        public OsmarenderPlugin() throws IOException {
                JMenuBar menu = Main.main.mainMenu;
                view = null;
                for (int i = 0; i < menu.getMenuCount(); ++i) {
                        if (menu.getMenu(i) != null && tr("View").equals(menu.getMenu(i).getName())) {
                                view = menu.getMenu(i);
                                break;
                        }
                }
                if (view == null) {
                        view = new JMenu(tr("View"));
                        Main.main.mainMenu.add(view, 1);
                        view.setVisible(false);
                }
                view.add(osmarenderMenu);
                osmarenderMenu.setVisible(false);

                // install the xsl and xml file
                copy("/osmarender.xsl", "osmarender.xsl");
                copy("/osm-map-features.xml", "osm-map-features.xml");
        }

        @Override
        public void mapFrameInitialized(MapFrame oldFrame, MapFrame newFrame) {
                if (oldFrame != null && newFrame == null) {
                        // disable
                        osmarenderMenu.setVisible(false);
                        if (view.getMenuComponentCount() == 1)
                                view.setVisible(false);
                } else if (oldFrame == null && newFrame != null) {
                        // enable
                        osmarenderMenu.setVisible(true);
                        if (view.getMenuComponentCount() == 1)
                                view.setVisible(true);
                }
        }
}