source: osm/applications/editors/josm/plugins/osmarender/src/OsmarenderPlugin.java@ 17518

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

import java.awt.event.ActionEvent;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.HashSet;

import javax.swing.JLabel;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;
import javax.swing.JTextField;

import org.openstreetmap.josm.Main;
import org.openstreetmap.josm.actions.JosmAction;
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.OsmPrimitive;
import org.openstreetmap.josm.data.osm.Way;
import org.openstreetmap.josm.data.osm.visitor.CollectBackReferencesVisitor;
import org.openstreetmap.josm.gui.MainMenu;
import org.openstreetmap.josm.gui.MapFrame;
import org.openstreetmap.josm.gui.preferences.PreferenceDialog;
import org.openstreetmap.josm.gui.preferences.PreferenceSetting;
import org.openstreetmap.josm.io.OsmWriter;
import org.openstreetmap.josm.plugins.Plugin;
import org.openstreetmap.josm.tools.GBC;

public class OsmarenderPlugin extends Plugin {

    private class Action extends JosmAction {

        public Action() {
            super(tr("Osmarender"), null, tr("Osmarender"), null, true);
        }

        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);

            try {
                writeGenerated(b);
            } catch(Exception ex) {
                //how handle the exception?
            }

            CollectBackReferencesVisitor backRefsV = new CollectBackReferencesVisitor(Main.main.getCurrentDataSet(), true);
            DataSet fromDataSet = new DataSet();
            for (Node n : Main.main.getCurrentDataSet().nodes) {
                if (n.isUsable() && n.getCoor().isWithin(b)) {
                    fromDataSet.nodes.add(n);
                    n.visit(backRefsV);
                }
            }
            for (OsmPrimitive p : new HashSet<OsmPrimitive>(backRefsV.data)) {
                if (p instanceof Way) {
                    for (Node n : ((Way) p).getNodes()) {
                        if (n.getCoor().isWithin(b))
                            backRefsV.data.add(n);
                    }
                }
            }
            for (OsmPrimitive p : backRefsV.data)
                fromDataSet.addPrimitive(p);

            String firefox = Main.pref.get("osmarender.firefox", "firefox");
            try {
                // write to plugin dir
                OsmWriter w = new OsmWriter(new PrintWriter(new FileOutputStream(getPluginDir()+File.separator+"data.osm")), false, fromDataSet.version);
                w.header();
                w.writeDataSources(fromDataSet);
                w.writeContent(fromDataSet);
                w.footer();
                w.close();

                // get the exec line
                String exec = firefox;
                if (System.getProperty("os.name").startsWith("Windows"))
                    exec += " file:///"+getPluginDir().replace('\\','/').replace(" ","%20")+File.separator+"generated.xml\"";
                else
                    exec += " "+getPluginDir()+File.separator+"generated.xml";

                // launch up the viewer
                Runtime.getRuntime().exec(exec);
            } catch (IOException e1) {
                JOptionPane.showMessageDialog(Main.parent, tr("Firefox not found. Please set firefox executable in the Map Settings page of the preferences."));
            }
        }
    }

    private JMenuItem osmarenderMenu;

    public OsmarenderPlugin() throws IOException {
        osmarenderMenu = MainMenu.add(Main.main.menu.viewMenu, new Action());
        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);
        } else if (oldFrame == null && newFrame != null) {
            // enable
            osmarenderMenu.setVisible(true);
        }
    }

    @Override public PreferenceSetting getPreferenceSetting() {
        return new PreferenceSetting(){
            private JTextField firefox = new JTextField(10);
            public void addGui(PreferenceDialog gui) {
                gui.map.add(new JLabel(tr("osmarender options")), GBC.eol().insets(0,5,0,0));
                gui.map.add(new JLabel(tr("Firefox executable")), GBC.std().insets(10,5,5,0));
                gui.map.add(firefox, GBC.eol().insets(0,5,0,0).fill(GBC.HORIZONTAL));
                firefox.setText(Main.pref.get("osmarender.firefox"));
            }
            public boolean ok() {
                Main.pref.put("osmarender.firefox", firefox.getText());
                return false;
            }
        };
    }

    private void writeGenerated(Bounds b) throws IOException {
        String bounds_tag = "<bounds " +
            "minlat=\"" + b.min.lat() + "\" " +
            "maxlat=\"" + b.max.lat() + "\" " +
            "minlon=\"" + b.min.lon() + "\" " +
            "maxlon=\"" + b.max.lon() + "\" " + "/>";

        BufferedReader reader = new BufferedReader(
                new FileReader( getPluginDir() + File.separator + "osm-map-features.xml") );
        PrintWriter writer = new PrintWriter( getPluginDir() + File.separator + "generated.xml");

        // osm-map-fetaures.xml contain two placemark
        // (bounds_mkr1 and bounds_mkr2). We write the bounds tag
        // between the two
        String str = null;
        while( (str = reader.readLine()) != null ) {
            if(str.contains("<!--bounds_mkr1-->")) {
                writer.println(str);
                writer.println("    " + bounds_tag);
                while(!str.contains("<!--bounds_mkr2-->")) {
                    str = reader.readLine();
                }
                writer.println(str);
            } else {
                writer.println(str);
            }
        }

        writer.close();
    }
}