Preliminary GRIB rendering for OpenMap

I have managed to render GRIB weather data in a OpenMap layer. It should support GRIB data from a numbers of free sources like NOAA.

Looks pretty cool with the isobars, wind arrows and a wind heat map.

The images below are showing a storm front (Xynthia) hitting Western Europe.

















Comments are welcome!

Geonames location searcher for OpenMap

Here is an integration of openmap with geonames that will add a combobox that can be used to search geonames.org to the toolbar by adding the following to your openmap.properties file:

openmap.components=... geonamessearcher
geonamessearcher.class=GeoNamesSearcher

Here is the code

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.DefaultComboBoxModel;
import javax.swing.DefaultListCellRenderer;
import javax.swing.JComboBox;
import javax.swing.JComponent;
import javax.swing.JList;
import javax.swing.plaf.basic.BasicComboBoxEditor;

import net.miginfocom.swing.MigLayout;

import org.apache.log4j.Logger;
import org.geonames.Toponym;
import org.geonames.ToponymSearchCriteria;
import org.geonames.ToponymSearchResult;
import org.geonames.WebService;

import com.bbn.openmap.event.CenterListener;
import com.bbn.openmap.event.CenterSupport;
import com.bbn.openmap.gui.OMToolComponent;

public class GeoNamesSearcher extends OMToolComponent {

 private static final Logger log = Logger.getLogger(GeoNamesSearcher.class
   .getName());

 private JComboBox searchBox;

 private CenterSupport centerDelegate;

 private DefaultComboBoxModel searchBoxModel = new DefaultComboBoxModel();

 public GeoNamesSearcher() {
  centerDelegate = new CenterSupport(this);
  setLayout(new MigLayout());
  searchBox = new JComboBox(searchBoxModel);
  searchBox.setEditable(true);
  searchBox.setMaximumRowCount(25);
  searchBox
    .setToolTipText("Enter part of location to search for (and center to).");
  searchBox.setRenderer(new DefaultListCellRenderer() {
   @Override
   public JComponent getListCellRendererComponent(JList list,
     Object value, int index, boolean isSelected,
     boolean cellHasFocus) {
    super.getListCellRendererComponent(list, value, index,
      isSelected, cellHasFocus);
    if (value instanceof Toponym) {
     Toponym toponym = (Toponym) value;
     setText(toponym.getName() + " " + toponym.getCountryCode());
    }
    return this;
   }
  });
  searchBox.setEditor(new BasicComboBoxEditor() {
   @Override
   public void setItem(Object anObject) {
    if (anObject != null) {
     if (anObject instanceof Toponym) {
      Toponym toponym = (Toponym) anObject;
      editor.setText(toponym.getName() + " "
        + toponym.getCountryCode());
      // oldValue = anObject;
     } else {
      super.setItem(anObject);
     }
    } else {
     editor.setText("");
    }
   }
  });


  searchBox.addActionListener(new ActionListener() {
   @Override
   public void actionPerformed(ActionEvent evt) {
    JComboBox cb = (JComboBox) evt.getSource();

    Object selectedItem = cb.getSelectedItem();

    if ("comboBoxEdited".equals(evt.getActionCommand())) {
     // User has typed in a string; only possible with an
     // editable combobox
     try {
      searchBoxModel.removeAllElements();
      ToponymSearchCriteria searchCriteria = new ToponymSearchCriteria();
      // searchCriteria.setCountryCode("DK");
      searchCriteria.setQ((String) selectedItem);
      ToponymSearchResult searchResult = WebService
        .search(searchCriteria);
      for (Toponym toponym : searchResult.getToponyms()) {
       searchBoxModel.addElement(toponym);
      }
      if (searchResult.getTotalResultsCount() == 1) {
       Toponym t = searchResult.getToponyms().get(0);
       centerDelegate.fireCenter(t.getLatitude(), t
         .getLongitude());
      } else if (searchResult.getTotalResultsCount() > 1) {
       searchBox.showPopup();
      }
     } catch (Exception e) {
      log.error("", e);
     }

    } else if ("comboBoxChanged".equals(evt.getActionCommand())) {
     // User has selected an item; it may be the same item
     if (cb.getSelectedItem() instanceof Toponym) {
      Toponym newItem = (Toponym) cb.getSelectedItem();
      centerDelegate.fireCenter(newItem.getLatitude(),
        newItem.getLongitude());
     }
    }

   }
  });
  add(searchBox);
 }

 public synchronized void addCenterListener(CenterListener listener) {
  centerDelegate.add(listener);
 }

 /**
  * Remove a CenterListener
  *
  * @param listener
  *            CenterListener
  */
 public synchronized void removeCenterListener(CenterListener listener) {
  centerDelegate.remove(listener);
 }

 @Override
 public void findAndInit(Object obj) {
  if (obj instanceof CenterListener) {
   addCenterListener((CenterListener) obj);
  }
 }

 @Override
 public void findAndUndo(Object obj) {
  if (obj instanceof CenterListener) {
   removeCenterListener((CenterListener) obj);
  }
 }
}

Using JavaFX Classes Directly From Java

Sitting on the Swing side of the fence the grass on the JavaFX side certainly sometimes seems a lot greener.


Knowing that the latest and greatest scene graph code is available somewhere in the pile of JavaFX jars it is tempting to try and get access to it from the Swing side without being "bothered" with the JavaFX language.

Other people like Matt Hicks have had the same thoughts (see I Hate JavaFX; I Love JavaFX!) so I started out with trying Matt's port of the JavaFX Clock and after some fiddling I got it up and running with JavaFX 1.2. Try it by pushing the launch button below.



The code follows (add all the JavaFX SDK jars to your classpath before trying this):

/**
 * @author Matt Hicks (matt@matthicks.com)
 */
public class Clock {
 private float radius = 77;
 private float centerX = 144;
 private float centerY = 144;
 private Calendar calendar = Calendar.getInstance();
 private int hours;
 private int minutes;
 private int seconds;

 private FloatVariable hoursVariable;
 private FloatVariable minutesVariable;
 private FloatVariable secondsVariable;

 public Clock() throws IOException {
  nextTick();

  // Build JavaFX clock
  Group group = new Group();
  {
   ImageView imageView = new ImageView();
   Image image = new Image();
   // should be image.set$url() but does not work ?
   image.loc$platformImage().set(
     ImageIO.read(getClass().getClassLoader().getResource(
       "clock_background.png")));
   imageView.set$image(image);
   group.loc$content().insert(imageView);

   Group face = new Group();
   {
    Translate translate = new Translate();
    translate.set$x(centerX);
    translate.set$y(centerY);
    face.loc$transforms.insert(translate);

    // Every third hour
    for (int i = 3; i <= 12; i += 3) {
     Text text = new Text();
     translate = new Translate();
     translate.set$x(-5.0f);
     translate.set$y(5.0f);
     text.loc$transforms.insert(translate);
     text.set$font(Font.font("Arial", 16));
     text.set$x(radius * ((i + 0) % 2 * (2 - i / 3)));
     text.set$y(radius * ((i + 1) % 2 * (3 - i / 3)));
     text.set$content(String.valueOf(i));
     face.loc$content.insert(text);
    }

    // Black circle for the rest of the hours
    for (int i = 1; i < 12; i++) {
     if (i % 3 == 0) {
      continue; // Don't show a circle on every third hour
     }

     Circle circle = new Circle();
     Rotate rotate = new Rotate();
     rotate.set$angle(30.0f * i);
     circle.loc$transforms.insert(rotate);
     circle.set$centerX(radius);
     circle.set$radius(3.0f);
     circle.set$fill(Color.$BLACK);
     face.loc$content.insert(circle);
    }

    // Center circles
    Circle circle = new Circle();
    circle.set$radius(5.0f);
    circle.set$fill(Color.$DARKRED);

    face.loc$content.insert(circle);
    circle = new Circle();
    circle.set$radius(3.0f);
    circle.set$fill(Color.$RED);
    face.loc$content.insert(circle);

    // Second hand
    Line line = new Line();
    {
     Rotate rotate = new Rotate();
     BindingExpression exp = new AbstractBindingExpression() {
      @Override
      public void compute() {
       pushValue(seconds * 6f);
      }
     };
     secondsVariable = FloatVariable.make(exp);
     rotate.loc$angle().bind(false, secondsVariable);

     line.loc$transforms.insert(rotate);

     line.set$endY(-radius - 3.0f);
     line.set$strokeWidth(2.0f);
     line.set$stroke(Color.$RED);
    }
    face.loc$content.insert(line);

    // Hour hand
    Path path = new Path();
    {
     Rotate rotate = new Rotate();
     BindingExpression exp = new AbstractBindingExpression() {
      @Override
      public void compute() {
       pushValue((float) (hours + minutes / 60) * 30 - 90);
      }
     };

     hoursVariable = FloatVariable.make(exp);
     rotate.loc$angle().bind(false, hoursVariable);
     path.loc$transforms.insert(rotate);

     path.set$fill(Color.$BLACK);

     MoveTo e1 = new MoveTo();
     e1.set$x(4.0f);
     e1.set$y(4.0f);
     path.loc$elements.insert(e1);
     ArcTo e2 = new ArcTo();
     e2.set$x(4.0f);
     e2.set$y(-4.0f);
     e2.set$radiusX(1.0f);
     e2.set$radiusY(1.0f);
     path.loc$elements.insert(e2);
     LineTo e3 = new LineTo();
     e3.set$x(radius - 15.0f);
     e3.set$y(0.0f);
     path.loc$elements.insert(e3);
    }
    face.loc$content.insert(path);

    // Minute hand
    path = new Path();
    {
     Rotate rotate = new Rotate();
     BindingExpression exp = new AbstractBindingExpression() {
      public void compute() {
       pushValue((float) minutes * 6 - 90);
      }
     };
     minutesVariable = FloatVariable.make(exp);
     rotate.loc$angle().bind(false, minutesVariable);

     path.loc$transforms.insert(rotate);
     path.set$fill(Color.$BLACK);

     MoveTo e1 = new MoveTo();
     e1.set$x(4.0f);
     e1.set$y(4.0f);
     path.loc$elements.insert(e1);
     ArcTo e2 = new ArcTo();
     e2.set$x(4.0f);
     e2.set$y(-4.0f);
     e2.set$radiusX(1.0f);
     e2.set$radiusY(1.0f);
     path.loc$elements.insert(e2);
     LineTo e3 = new LineTo();
     e3.set$x(radius);
     e3.set$y(0.0f);
     path.loc$elements.insert(e3);
    }
    face.loc$content.insert(path);

    group.loc$content.insert(face);
   }
  }

  Timeline timeline = new Timeline();
  timeline.set$repeatCount(Timeline.$INDEFINITE);

  KeyFrame kf = new KeyFrame();
  kf.set$time(Duration.valueOf(1000.0f));
  kf.set$canSkip(true);
  kf.set$action(new Function0<Void>() {
   public Void invoke() {
    nextTick();
    return null;
   }
  });
  timeline.loc$keyFrames.insert(kf);
  // this is somewhat hairy JFxtras does it like this I think
  Scene scene = new Scene();
  scene.loc$content().insert(group);
  JPanel panel = new JPanel(new BorderLayout());
  TKScene fxNode = scene.get$javafx$scene$Scene$impl_peer();
  panel.add(((SwingScene) fxNode).scenePanel, BorderLayout.CENTER);
  JFrame frame = new JFrame("JavaFX Clock Example");
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  frame.add(panel);
  frame.setSize(295, 325);
  frame.setVisible(true);
  timeline.play();
 }

 public void nextTick() {
  calendar.setTimeInMillis(System.currentTimeMillis());
  seconds = calendar.get(Calendar.SECOND);
  minutes = calendar.get(Calendar.MINUTE);
  hours = calendar.get(Calendar.HOUR_OF_DAY);
  // trigger bindings to re calc and move hands
  if (secondsVariable != null) {
   secondsVariable.invalidate();
   minutesVariable.invalidate();
   hoursVariable.invalidate();
  }
 }

 public static void main(String[] args) throws Exception {
  SwingUtilities.invokeLater(new Runnable() {
   @Override
   public void run() {
    try {
     new Clock();
    } catch (Exception e) {
     e.printStackTrace();
    }
   }
  });
 }
}

For comparison the JavaFX version follows here:

public class Clock extends CustomNode {

    public var radius: Number = 77;
    public var centerX: Number = 144;
    public var centerY: Number = 144;

    public var hours:Number;
    public var minutes:Number;
    public var seconds:Number;

    public function nextTick () {
        var now = new Date();
        seconds = now.getSeconds();
        minutes = now.getMinutes();
        hours = now.getHours();
    }

    public override function create() : Node {
        return Group {
            content: [
                ImageView {
                    image: Image {
                        url: "{__DIR__}clock_background.png"
                    }
                },
                Group {
                    transforms: Translate {
                        x: centerX,
                        y: centerY
                    }
                    content: [
                        // code to display the numbers for every third hour
                        for (i in [3, 6, 9, 12])
                        Text {
                            transforms: Translate {
                                x: -5,
                                y: 5
                            }
                            font: Font {
                                size: 16
                            }
                            x: radius * (( i + 0 ) mod 2 * ( 2 - i / 3))
                            y: radius * (( i + 1 ) mod 2 * ( 3 - i / 3))
                            content: "{i}"
                        },  //Text


                        //code to display a black circle for the rest of the hours on the clock
                        for (i in [1..12])
                        if (i mod 3 != 0 ) then Circle {
                            transforms: Rotate {
                                angle: 30 * i
                            }
                            centerX: radius
                            radius: 3
                            fill: Color.BLACK
                        } //for
                        else [ ],

                        // code for the clock's first center circle
                        Circle {
                            radius: 5
                            fill: Color.DARKRED
                        }, //Circle
                        //code for the smaller center circle
                        Circle {
                            radius: 3
                            fill: Color.RED
                        }, //Circle
                        //code for the seconds hand
                        Line {
                            transforms: Rotate {
                                angle: bind seconds * 6
                            }
                            endY: -radius - 3
                            strokeWidth: 2
                            stroke: Color.RED
                        },  //Line
                        //code for the hour hand
                        Path {
                            transforms: Rotate {
                                angle: bind (hours + minutes / 60) * 30 - 90
                            }
                            fill: Color.BLACK
                            elements: [
                                MoveTo {
                                    x: 4,
                                y: 4},
                                ArcTo {
                                    x: 4
                                    y: -4
                                    radiusX: 1
                                radiusY: 1},
                                LineTo{
                                    x: radius - 15
                                y: 0},
                            ] //elements
                        },  // Path
                        // code for the minutes hand
                        Path {
                            transforms: Rotate {
                                angle: bind minutes * 6 - 90
                            }
                            fill: Color.BLACK
                            elements: [
                                MoveTo {
                                    x: 4,
                                y: 4},
                                ArcTo {
                                    x: 4
                                    y: -4
                                    radiusX: 1
                                radiusY: 1},
                                LineTo{
                                    x: radius
                                y: 0},
                            ] // elements
                        } // Path
                    ] //content
                }
            ]
        };
    }

    init {
        var timeline = Timeline {
            repeatCount: Timeline.INDEFINITE
            keyFrames: [
                KeyFrame {
                    time: 1s
                    canSkip: true
                    action: function() {
                        nextTick();
                    }
                }
            ]
        }
        timeline.play();
    }
}

Web start depolyment is rather easy as it is possible to take advantage of the JavaFX extension and just add:

to your jnlp file and then do the usual jnlp stuff.

Country Flag Decorations On Your Swing Components

Here is how to get country flag icon decorations on your JTable cells, JList cells, JCombobox'es and JTextFields.




First you need to grab the Flag Icons from the famfamfam site and package them into a jar file and add it to your classpath. The JTextField flag decoration is done via the BuddySupport in the xswingx project.

Then we need to set up a mapping of country names to famfamfam icon names like this:

  private final String[] countries = { "AFGHANISTAN", "AF", "ÅLAND ISLANDS",...}
  Map<String, String> countryMap = new HashMap<String, String>();
  for (int i = 0; i < countries.length;) {
   countryMap.put(countries[i], countries[i + 1]);
   i += 2;
  }
  countryFlagDecorator = new CountryFlagDecorator(countryMap);
  // lazy do CountryFlagDecorator.getInstance() and skip the above mapping setup

Now we can decorate e.g., a JCombobox like this:

  JComboBox flagCombo = new JComboBox(new String[] { "DENMARK", "SWEDEN",
    "NORWAY" });
  countryFlagDecorator.addCountryFlagDecorations(flagCombo);

A JTable cell like this:

  JTable jt = new JTable(data, fields);
  TableColumn col = jt.getColumnModel().getColumn(2);
  col.setCellRenderer(new CountryFlagTableCellRendere(
    countryFlagDecorator));
  col.setCellEditor(new CountryFlagCellEditor(countryFlagDecorator,
    new String[] { "DENMARK", "SWEDEN", "NORWAY" }));

A Jlist (with a small twist)

  JList flagList = new JList(new String[] { "DK", "SE", "NO", "US" });
  flagList.setCellRenderer(new CountryFlagListCellRendere(
    countryFlagDecorator, new CountryNameConverter() {
     @Override
     public String convertCountryName(String countryName) {
      if ("DK".equals(countryName)) {
       return "DENMARK";
      } else if ("SE".equals(countryName)) {
       return "SWEDEN";
      } else if ("NO".equals(countryName)) {
       return "NORWAY";
      } else if ("US".equals(countryName)) {
       return "UNITED STATES";
      }
      return null;
     }
    }));

And a JTextField like this:

  JTextField flagField = new JTextField("");
  PromptSupport.setPrompt("Write name of a country, e.g., DENMARK", flagField);
  countryFlagDecorator.addCountryFlag(flagField, null);

Download the source

Google Earth 3D Vessel Models With Swing & Jetty

Using a Swing GUI with an embedded instance of Jetty a real time stream of vessel position information (AIS data) is converted into KML.This converts Google Earth into a low cost (free) AIS Display system. Vessels can be displayed as 3D models that are scaled according to AIS information





You can give it a spin (Google Earth needs to be installed) by pushing the launch button below.

Fancy JLabels With JHLabs Filters

Recently I was looking for a way to create "fancy" text for some title panes and I stumbled over JHLabs Image Filters.





Over at JHLabs there are examples of how to create e.g., glowing text:



Or chrome like text:



To get a simmlar effect on a JLabel just replace the JLabel with a JHLabsLabel e.g.;

JLabel label = new JHLabsLabel("Hello World", new ChromeFilter(), new ShadowFilter(5, 5, 2, .7f));

Here is the code for JHLabsLabel:

 /**
  * Notice that this is not perfect wrt alignment to see just uncomment super.paintComponent(g) 
  * Maybe somebody with BasicLabelUI knowledge could help?
  * 
  */
 public static final class JHLabsLabel extends JLabel {

  private int textX;

  private int textY;

  private AbstractBufferedImageOp[] filters;

  public JHLabsLabel(String string, AbstractBufferedImageOp... filters) {
   super(string);
   this.filters = filters;
  }

  @Override
  public void paintComponent(Graphics g) {

   // super.paintComponent(g);

   BufferedImage img = createTextImage(getText(), getFont());

   for (AbstractBufferedImageOp f : filters) {
    img = f.filter(img, null);
   }

   // g.drawImage(f.filter(img, null), textX, textY, null);
   g.drawImage(img, textX, textY, null);
  }

  private BufferedImage createTextImage(String text, Font font) {

   Rectangle paintIconR = new Rectangle();
   Rectangle paintTextR = new Rectangle();
   Rectangle paintViewR = new Rectangle();
   Insets paintViewInsets = new Insets(0, 0, 0, 0);

   paintViewInsets = getInsets(paintViewInsets);
   paintViewR.x = paintViewInsets.left;
   paintViewR.y = paintViewInsets.top;
   paintViewR.width = getWidth()
     - (paintViewInsets.left + paintViewInsets.right);
   paintViewR.height = getHeight()
     - (paintViewInsets.top + paintViewInsets.bottom);

   String clippedText = SwingUtilities.layoutCompoundLabel(
     (JComponent) this, getFontMetrics(getFont()), text,
     getIcon(), getVerticalAlignment(),
     getHorizontalAlignment(), getVerticalTextPosition(),
     getHorizontalTextPosition(), paintViewR, paintIconR,
     paintTextR, getIconTextGap());

   boolean isAntiAliased = true;
   boolean usesFractionalMetrics = false;
   FontRenderContext frc = new FontRenderContext(null, isAntiAliased,
     usesFractionalMetrics);
   TextLayout layout = new TextLayout(clippedText, font, frc);
   Rectangle2D bounds = layout.getBounds();
   int w = (int) Math.ceil(bounds.getWidth());
   int h = (int) Math.ceil(bounds.getHeight());
   BufferedImage image = new BufferedImage(w, h,
     BufferedImage.TYPE_INT_ARGB);
   Graphics2D g = image.createGraphics();
   g.setColor(new Color(0, 0, 0, 0));
   g.fillRect(0, 0, w, h);
   g.setColor(getForeground());
   g.setFont(font);
   Object antiAliased = isAntiAliased ? RenderingHints.VALUE_TEXT_ANTIALIAS_ON
     : RenderingHints.VALUE_TEXT_ANTIALIAS_OFF;
   g.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING,
     antiAliased);
   Object fractionalMetrics = usesFractionalMetrics ? RenderingHints.VALUE_FRACTIONALMETRICS_ON
     : RenderingHints.VALUE_FRACTIONALMETRICS_OFF;
   g.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS,
     fractionalMetrics);
   g.drawString(clippedText, (float) -bounds.getX(), (float) -bounds
     .getY());
   // g.drawString(clippedText, (float) 0, (float) 0);
   g.dispose();

   textX = paintTextR.x;
   textY = paintTextR.y;// + getFontMetrics(font).getAscent() / 2;
   System.out.println(String.format("X=%d Y=%d, w=%d h=%d", textX,
     textY, w, h));

   return image;
  }

 }

I also could not resist to play to the JHLabs texture filters as background painters e.g.,

JXPanel woodPanel = new JXPanel();
woodPanel.setBackgroundPainter(new JHTexturePainter<JXPanel>(new CausticsFilter(), new SparkleFilter()));

Creates the initial background for the demo.

Here is the code for JHTexturePainter:

 /**
  * 
  * Paint the background using a combination of the JHLabs image filters
  * 
  * @param <T>
  */
 static final class JHTexturePainter<T> implements Painter<T> {

  private AbstractBufferedImageOp[] filters;

  public JHTexturePainter(AbstractBufferedImageOp... filters) {
   this.filters = filters;
  }

  @Override
  public void paint(Graphics2D g2d, T arg1, int w, int h) {
   BufferedImage image = new BufferedImage(w, h,
     BufferedImage.TYPE_INT_ARGB);
   Graphics2D g = image.createGraphics();
   g.setColor(new Color(0, 0, 0, 0));
   g.fillRect(0, 0, w, h);

   for (AbstractBufferedImageOp f : filters) {
    image = f.filter(image, null);
   }
   g.dispose();
   g2d.drawImage(image, 0, 0, null);
  }

 }

Build your own GPS/GIS system in less than 200 lines with OpenMap

Here is how to do your own (simplistic) GPS/GIS system using OpenMap in less than 200 lines of code. To get started you will need to download and install OpenMap.

The GPS Layer for OpenMap is as follows. Notice that the code is somewhat crude with regards to threading, drizzel some synchronized on to it as appropriate.

public class GPSLayer extends OMGraphicHandlerLayer {

private static String GPSDATA = "gpsData";

private static final double KT2MPS = 1852.0 / 3600.0;

private static final double speedVectorLengthInMinutes = 6;

private String gpsDataPath = "";

private float latitude, longitude, speed, course;

private OMGraphicList graphics = new OMGraphicList();;

private OMRect gpsPosition = new OMRect(0, 0, 0, 0, 10, 10);

private OMLine speedVector;

private OMText gpsText = new OMText(10, 20, "GPS Data",
OMText.JUSTIFY_LEFT);

private Timer timer;

public GPSLayer() {
gpsText.setFillPaint(Color.WHITE);
gpsText.setTextMatteColor(new Color(182, 235, 219));
gpsPosition.setFillPaint(Color.pink);
}

@Override
public void setProperties(String prefix, Properties props) {
super.setProperties(prefix, props);
gpsDataPath = props.getProperty(prefix + "." + GPSDATA);
// redraw every 5 secs
timer = new Timer(5000, this);
timer.start();

// emulate reading GPS data (threading issue here access to members not
// protected!)
new Thread(new Runnable() {
public void run() {
 try {
  BufferedReader in = new BufferedReader(new FileReader(
    gpsDataPath));
  String str;
  while ((str = in.readLine()) != null) {
   Thread.sleep(100);
   if (str.startsWith("$GPRMC")) {
    String[] fields = str.split(",");
    // utc_date = fields[1];
    double lat = Double.parseDouble(fields[3]);
    double degrees = Math.floor((lat / 100.0));
    double minute = (lat / 100.0) - degrees;
    lat = (degrees) + ((minute * 100.0) / 60);
    if (fields[4].equals("S"))
     lat = -lat;
    latitude = (float) lat;

    double lon = Double.parseDouble(fields[5]);
    degrees = Math.floor((lon / 100.0));
    minute = (lon / 100.0) - degrees;
    lon = (degrees) + ((minute * 100.0) / 60);
    if (fields[6].equals("W"))
     lon = -lon;
    longitude = (float) lon;

    speed = (float) (Double.parseDouble(fields[7]) * KT2MPS);

    if (!fields[8].equals("")) {
     course = (float) Double.parseDouble(fields[8]);
    }
    // could parse date but to lazy
    // date = fields[9];
   }
  }
  in.close();
 } catch (Exception e) {
  e.printStackTrace();
 }
}
}).start();
}

@Override
public synchronized OMGraphicList prepare() {
gpsPosition.setLocation(latitude, longitude, -5, -5, 5, 5);

// calc. speed vector length using OM GIS functions
LatLonPoint startPos = new LatLonPoint(latitude, longitude);
float length = (float) Length.KM.toRadians(speedVectorLengthInMinutes
 * ((speed * 3.6) / 60.0));
LatLonPoint endPos = startPos.getPoint(length, (float) ProjMath
 .degToRad(course));
speedVector = new OMLine(startPos.getLatitude(), startPos
 .getLongitude(), endPos.getLatitude(), endPos.getLongitude(),
 OMLine.LINETYPE_STRAIGHT);
// vec.addArrowHead(OMArrowHead.ARROWHEAD_DIRECTION_FORWARD, 100, 3, 1);
speedVector.setLinePaint(Color.DARK_GRAY);

graphics.clear();
// order of add determines what is rendered on top
graphics.add(speedVector);
graphics.add(gpsPosition);
gpsText.setData(String.format("GPS Data\n%4.2f Km/h",
 (speed * 3.60)));
graphics.add(gpsText);

graphics.project(getProjection());
return graphics;
}

@Override
public void actionPerformed(ActionEvent ae) {
doPrepare();
}
}

If you have a GPS antenna you can use one of the free GPS servers (gpsd on linux) to make its data available on a socket and then modify the in variable in reader thread to the following:

uc = new URL(gpsDataPath).openConnection(); // gps.gpsData=http://localhost:2244
InputStreamReader icr = new InputStreamReader(uc.getInputStream());
in = new BufferedReader(icr);

To run this put the above class into a jar file and copy it to the lib dir of the OpenMap installation. Then in the share dir create a openmap.properties file with the following content:

openmap.layers=gps graticule shapePolitical
openmap.startUpLayers=gps graticule shapePolitical

gps.class=GPSLayer
gps.prettyName=GPS Position
gps.gpsData=/tmp/gpslog.txt

Then go to the bin dir of the OpenMap installation and do ./openmap(.bat) and your GPS/GIS system will be running.

Then following can be used as test data

$GPRMC,143346,A,5616.9232,N,01008.2504,E,074.6,011.3,110105,000.9,E,A*13
$GPRMC,143347,A,5616.9435,N,01008.2571,E,074.5,010.4,110105,000.9,E,A*14
$GPRMC,143348,A,5616.9638,N,01008.2632,E,074.4,009.5,110105,000.9,E,A*18
$GPRMC,143349,A,5616.9842,N,01008.2686,E,074.3,008.4,110105,000.9,E,A*12