Implement radio button support in LayerSwitcher. Pass in {mode:'radio'} to constructor to switch away from checkbox mode, which is default. This allows us to complete the original part of #32, although we do not yet support the concept of 'base layers' described in that ticket, which has been split to #62.

git-svn-id: http://svn.openlayers.org/trunk/openlayers@361 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Control/LayerSwitcher.js

@@ -28,14 +28,17 @@ OpenLayers.Control.LayerSwitcher.prototype =
     /** @type String */
     nonActiveColor: "",
     
+    /** @type String */
+    mode: "checkbox",
 
     /**
     * @constructor
     */
-    initialize: function() {
+    initialize: function(options) {
-        OpenLayers.Control.prototype.initialize.apply(this, arguments);
         this.activeColor = OpenLayers.Control.LayerSwitcher.ACTIVE_COLOR;
         this.nonActiveColor = OpenLayers.Control.LayerSwitcher.NONACTIVE_COLOR;
+        this.backdrops = [];
+        OpenLayers.Control.prototype.initialize.apply(this, arguments);
     },
 
     /**
@@ -71,10 +74,16 @@ OpenLayers.Control.LayerSwitcher.prototype =
 
         //clear out previous incarnation of LayerSwitcher tabs
         this.div.innerHTML = "";
-    
+        var visible = false;
         for( var i = 0; i < this.map.layers.length; i++) {
+            if (visible && this.mode == "radio") {
+                this.map.layers[i].setVisibility(false);
+            } else {
+                visible = this.map.layers[i].getVisibility();
+            }
             this.addTab(this.map.layers[i]);
         }
+            
         return this.div;
     },
     
@@ -84,10 +93,19 @@ OpenLayers.Control.LayerSwitcher.prototype =
     singleClick: function(evt) {
         var div = Event.element(evt);
         var layer = div.layer;
+        if (this.mode == "radio") {
+            for(var i=0; i < this.backdrops.length; i++) {
+                this.setTabActivation(this.backdrops[i], false);
+                this.backdrops[i].layer.setVisibility(false);
+            }
+            this.setTabActivation(div, true);
+            layer.setVisibility(true);
+        } else {
             var visible = layer.getVisibility();
             
             this.setTabActivation(div, !visible);
             layer.setVisibility(!visible);
+        }
         Event.stop(evt);
     },
     
@@ -132,6 +150,8 @@ OpenLayers.Control.LayerSwitcher.prototype =
         // add label to div
         backdropLabelOuter.appendChild(backdropLabel);
         
+        this.backdrops.append(backdropLabel); 
+        
         // add div to main LayerSwitcher Div
         this.div.appendChild(backdropLabelOuter);