Index: /trunk/src/org/openstreetmap/josm/data/projection/Projection.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/data/projection/Projection.java	(revision 1581)
+++ /trunk/src/org/openstreetmap/josm/data/projection/Projection.java	(revision 1582)
@@ -35,5 +35,6 @@
         new Mercator(),
         new Lambert(),
-        new LambertEST()
+        new LambertEST(),
+        new SwissGrid()
     };
 
Index: /trunk/src/org/openstreetmap/josm/data/projection/SwissGrid.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/data/projection/SwissGrid.java	(revision 1582)
+++ /trunk/src/org/openstreetmap/josm/data/projection/SwissGrid.java	(revision 1582)
@@ -0,0 +1,158 @@
+//License: GPL. For details, see LICENSE file.
+
+package org.openstreetmap.josm.data.projection;
+
+import static org.openstreetmap.josm.tools.I18n.tr;
+
+import javax.swing.JOptionPane;
+
+import org.openstreetmap.josm.Main;
+import org.openstreetmap.josm.data.coor.EastNorth;
+import org.openstreetmap.josm.data.coor.LatLon;
+
+/**
+ * Projection for the SwissGrid, see http://de.wikipedia.org/wiki/Swiss_Grid.
+ *
+ * Calculations are based on formula from
+ * http://www.swisstopo.admin.ch/internet/swisstopo/en/home/topics/survey/sys/refsys/switzerland.parsysrelated1.37696.downloadList.12749.DownloadFile.tmp/ch1903wgs84en.pdf
+ *
+ */
+public class SwissGrid implements Projection {
+    private boolean doAlertOnCoordinatesOufOfRange = true;
+
+    /**
+     * replies true if if wgs is in or reasonably close to Switzerland. False otherwise.
+     *
+     * @param wgs  lat/lon in WGS89
+     * @return
+     */
+    protected boolean latlonInAcceptableRange(LatLon wgs) {
+        // coordinate transformation is invoked for boundary values regardless
+        // of current data set.
+        //
+        if (Math.abs(wgs.lon()) == Projection.MAX_LON && Math.abs(wgs.lat()) == Projection.MAX_LAT) {
+            return true;
+        }
+        return   wgs.lon() >= 5.7 && wgs.lon() <= 10.6
+               && wgs.lat() >= 45.7 && wgs.lat() <= 47.9;
+    }
+
+    /**
+     * displays an alert if lat/lon are not reasonably close to Switzerland.
+     */
+    protected void alertCoordinatesOutOfRange() {
+        JOptionPane.showMessageDialog(Main.parent,
+                tr("The projection \"{0}\" is designed for\n"
+                + "latitudes between 45.7' and 47.9'\n"
+                + "and longitutes between 5.7' and 10.6' only.\n"
+                + "Use another projection system if you are not working\n"
+                + "on a data set of Switzerland or Liechtenstein.\n"
+                + "Do not upload any data after this message.", this.toString()),
+                "Current projection not suitable",
+                JOptionPane.WARNING_MESSAGE
+        );
+        doAlertOnCoordinatesOufOfRange = false;
+    }
+
+    /**
+     * @param wgs  WGS84 lat/lon (ellipsoid GRS80) (in degree)
+     * @return eastnorth projection in Swiss National Grid (ellipsoid Bessel)
+     */
+    public EastNorth latlon2eastNorth(LatLon wgs) {
+            if (!latlonInAcceptableRange(wgs)) {
+                if (doAlertOnCoordinatesOufOfRange) {
+                    alertCoordinatesOutOfRange();
+                }
+            }
+
+            double phi = 3600d * wgs.lat();
+            double lambda = 3600d * wgs.lon();
+
+            double phiprime = (phi - 169028.66d) / 10000d;
+            double lambdaprime = (lambda - 26782.5d) / 10000d;
+
+            // precompute squares for lambdaprime and phiprime
+            //
+            double lambdaprime_2 = Math.pow(lambdaprime,2);
+            double phiprime_2 = Math.pow(phiprime,2);
+
+
+            double north =
+                  200147.07d
+                + 308807.95d                           * phiprime
+                +   3745.25d    * lambdaprime_2
+                +     76.63d                           * phiprime_2
+                -    194.56d    * lambdaprime_2        * phiprime
+                +    119.79d                           * Math.pow(phiprime,3);
+
+
+            double east =
+                  600072.37d
+                + 211455.93d  * lambdaprime
+                - 10938.51d   * lambdaprime             * phiprime
+                - 0.36d       * lambdaprime             * phiprime_2
+                - 44.54d      * Math.pow(lambdaprime,3);
+
+            return new EastNorth(east, north);
+    }
+
+    /**
+     * @param xy SwissGrid east/north (in meters)
+     * @return LatLon WGS84 (in degree)
+     */
+
+    public LatLon eastNorth2latlon(EastNorth xy) {
+        double yp = (xy.east() - 600000d) / 1000000d;
+        double xp = (xy.north() - 200000d) / 1000000d;
+
+        // precompute squares of xp and yp
+        //
+        double xp_2 = Math.pow(xp,2);
+        double yp_2 = Math.pow(yp,2);
+
+        // lambda = latitude, phi = longitude
+        double lmbp  =    2.6779094d
+                        + 4.728982d      * yp
+                        + 0.791484d      * yp               * xp
+                        + 0.1306d        * yp               * xp_2
+                        - 0.0436d        * Math.pow(yp,3);
+
+        double phip =     16.9023892d
+                        +  3.238272d                        * xp
+                        -  0.270978d    * yp_2
+                        -  0.002528d                        * xp_2
+                        -  0.0447d      * yp_2              * xp
+                        -  0.0140d                          * Math.pow(xp,3);
+
+        double lmb = lmbp * 100.0d / 36.0d;
+        double phi = phip * 100.0d / 36.0d;
+
+        return new LatLon(phi,lmb);
+    }
+
+    public double scaleFactor() {
+        return 1.0;
+    }
+
+    @Override public String toString() {
+        return tr("Swiss Grid (Switzerland)");
+    }
+
+    public String toCode() {
+        return "EPSG:21781";
+    }
+
+    public String getCacheDirectoryName() {
+        return "swissgrid";
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        return o instanceof SwissGrid;
+    }
+
+    @Override
+    public int hashCode() {
+        return SwissGrid.class.hashCode();
+    }
+}