Remember which layers are active in the cookie and URLs.

app/views/site/index.rhtml

@@ -10,12 +10,14 @@
 <% lon =  params['lon'] %>
 <% lat =  params['lat'] %>
 <% zoom =  params['zoom'] || '5' %>
+<% layers = params['layers'] %>
 <% elsif params['mlon'] and params['mlat'] %>
 <% lon = params['mlon'] %> 
 <% lat = params['mlat'] %>
 <% zoom =  params['zoom'] || '12' %>
+<% layers = params['layers'] %>
 <% elsif cookies.key?("location") %>
-<% lon,lat,zoom = cookies["location"].value.first.split(",") %>
+<% lon,lat,zoom,layers = cookies["location"].value.first.split(",") %>
 <% elsif @user and !@user.home_lon.nil? and !@user.home_lat.nil? %> 
 <% lon =  @user.home_lon %>
 <% lat =  @user.home_lat %>
@@ -24,6 +26,7 @@
 <% lon =  '-0.1' %>
 <% lat =  '51.5' %>
 <% zoom =  params['zoom'] || '5' %>
+<% layers = params['layers'] %>
 <% end %>
 
 <script type="text/javascript" src="/openlayers/OpenLayers.js"></script>
@@ -42,6 +45,7 @@
   function init(){
     var centre = lonLatToMercator(new OpenLayers.LonLat(<%= lon %>, <%= lat %>));
     var zoom = <%= zoom %>;
+    var layers = "<%= layers %>";
 
     <% if params['scale'] and params['scale'].length > 0 then %>
     zoom = scaleToZoom(<%= params['scale'].to_f() %>);
@@ -53,6 +57,10 @@
     addMarkerToMap(lonLatToMercator(new OpenLayers.LonLat(<%= mlon %>, <%= mlat %>)));
     <% end %>
 
+    <% if layers %>
+    setMapLayers(layers);
+    <% end %>
+
     map.events.register("moveend", map, updateLocation);
     updateLocation();
 
@@ -73,10 +81,11 @@
   function updateLocation() {
     var lonlat = mercatorToLonLat(map.getCenter());
     var zoom = map.getZoom();
+    var layers = getMapLayers();
 
-    updatelinks(lonlat.lon, lonlat.lat, zoom);
+    updatelinks(lonlat.lon, lonlat.lat, zoom, layers);
 
-    document.cookie = "location=" + lonlat.lon + "," + lonlat.lat + "," + zoom;
+    document.cookie = "location=" + lonlat.lon + "," + lonlat.lat + "," + zoom + "," + layers;
   }
 
   function getStyle( el, property ) {

public/javascripts/map.js

@@ -24,6 +24,9 @@ function createMap(divName, centre, zoom) {
                                              { type: 'png', getURL: getTileURL, displayOutsideMaxExtent: true });
    map.addLayer(osmarender);
 
+   markers = new OpenLayers.Layer.Markers("markers", { visibility: false });
+   map.addLayer(markers);
+
    map.addControl(new OpenLayers.Control.LayerSwitcher());
    map.setCenter(centre, zoom);
 
@@ -50,14 +53,10 @@ function getTileURL(bounds) {
 }
 
 function addMarkerToMap(position, icon, description) {
-   if (markers == null) {
-      markers = new OpenLayers.Layer.Markers("markers");
-      map.addLayer(markers);
-   }
-
    var marker = new OpenLayers.Marker(position, icon);
 
    markers.addMarker(marker);
+   markers.setVisibility(true);
 
    if (description) {
       marker.events.register("click", marker, function() { openMapPopup(marker, description) });
@@ -96,6 +95,35 @@ function removeMarkerFromMap(marker){
    markers.removeMarker(marker);
 }
 
+function getMapLayers() {
+   var layers = "";
+
+   for (var i=0; i< this.map.layers.length; i++) {
+      var layer = this.map.layers[i];
+
+      if (layer.isBaseLayer) {
+         layers += (layer == this.map.baseLayer) ? "B" : "0";
+      } else {
+         layers += (layer.getVisibility()) ? "T" : "F";
+      }
+   }
+
+   return layers;
+}
+
+function setMapLayers(layers) {
+   for (var i=0; i < layers.length; i++) {
+      var layer = map.layers[i];
+      var c = layers.charAt(i);
+
+      if (c == "B") {
+         map.setBaseLayer(layer);
+      } else if ( (c == "T") || (c == "F") ) {
+         layer.setVisibility(c == "T");
+      }
+   }
+}
+
 function mercatorToLonLat(merc) {
    var lon = (merc.lon / 20037508.34) * 180;
    var lat = (merc.lat / 20037508.34) * 180;

public/javascripts/site.js

@@ -1,4 +1,4 @@
-function updatelinks(lon,lat,zoom) {
+function updatelinks(lon,lat,zoom,layers) {
   var links = new Object();
   links['viewanchor'] = '/index.html';
   //links['editanchor'] = 'edit.html';
@@ -16,6 +16,7 @@ function updatelinks(lon,lat,zoom) {
     args["lat"] = lat;
     args["lon"] = lon;
     args["zoom"] = zoom;
+    args["layers"] = layers;
     node.href = setArgs(node.href, args);
   }