For #100 - updated radius calculation with formula taken from mailing…

… list
vitalidze · Mar 28, 2015 · 55f4ed3 · 55f4ed3
1 parent b51fc4b
commit 55f4ed3
Showing 1 changed file with 12 additions and 3 deletions.
diff --git a/src/main/java/org/traccar/web/client/view/GeoFenceRenderer.java b/src/main/java/org/traccar/web/client/view/GeoFenceRenderer.java
@@ -66,8 +66,7 @@ public void removeGeoFence(GeoFence geoFence) {
 
     private void drawCircle(GeoFence circle, boolean drawTitle) {
         GeoFence.LonLat center = circle.points().get(0);
-        float radius = circle.getRadius() * 1.78143299863f;
-        Polygon circleShape = Polygon.createRegularPolygon(mapView.createPoint(center.lon, center.lat), radius, 100, 0f);
+        Polygon circleShape = Polygon.createRegularPolygon(mapView.createPoint(center.lon, center.lat), applyMercatorScale(center.lat, circle.getRadius()), 100, 0f);
 
         Style st = new Style();
         st.setFillOpacity(0.3);
@@ -122,7 +121,7 @@ private void drawLine(GeoFence line, boolean drawTitle) {
 
         LineString lineString = new LineString(linePoints);
         VectorFeature lineFeature = new VectorFeature(lineString);
-        lineFeature.getAttributes().setAttribute("widthInMeters", line.getRadius() * 1.78143299863f);
+        lineFeature.getAttributes().setAttribute("widthInMeters", applyMercatorScale(lonLats.get(0).lat, line.getRadius()));
         lineFeature.getAttributes().setAttribute("lineColor", '#' + line.getColor());
 
         getVectorLayer().addFeature(lineFeature);
@@ -133,6 +132,16 @@ private void drawLine(GeoFence line, boolean drawTitle) {
         }
     }
 
+    /**
+     * Applies scale to specified radius in meters so it is precisely drawn on map
+     *
+     * @see <a href="http://osdir.com/ml/openlayers-users-gis/2012-09/msg00034.html">http://osdir.com/ml/openlayers-users-gis/2012-09/msg00034.html</a>
+     * @see <a href="http://osdir.com/ml/openlayers-users-gis/2012-09/msg00036.html">http://osdir.com/ml/openlayers-users-gis/2012-09/msg00036.html</a>
+     */
+    private float applyMercatorScale(double latitude, float radius) {
+        return (float) (radius / Math.cos(latitude * Math.PI / 180));
+    }
+
     private VectorFeature drawName(String name, Point point) {
         org.gwtopenmaps.openlayers.client.Style st = new org.gwtopenmaps.openlayers.client.Style();
         st.setLabel(name);