Add map.getNumLayers(), map.getLayerIndex(), map.setLayerIndex(), map.raiseLayer() to support moving layers up and down in the map stack.

git-svn-id: http://svn.openlayers.org/trunk/openlayers@1604 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Map.js

@@ -255,14 +255,23 @@ OpenLayers.Map.prototype = {
         return foundLayer;
     },
 
+    /**
+    * @param {OpenLayers.Layer} layer
+    * @param {int} zIdx
+    * @private
+    */    
+    setLayerZIndex: function (layer, zIdx) {
+        layer.div.style.zIndex = 
+            this.Z_INDEX_BASE[layer.isBaseLayer ? 'BaseLayer' : 'Overlay']
+            + zIdx * 5;
+    },
+
     /**
     * @param {OpenLayers.Layer} layer
     */    
     addLayer: function (layer) {
         layer.div.style.overflow = "";
-        layer.div.style.zIndex = 
-            this.Z_INDEX_BASE[layer.isBaseLayer ? 'BaseLayer' : 'Overlay']
-            + this.layers.length * 5;
+        this.setLayerZIndex(layer, this.layers.length);
 
         if (layer.isFixed) {
             this.viewPortDiv.appendChild(layer.div);
@@ -347,6 +356,62 @@ OpenLayers.Map.prototype = {
         this.events.triggerEvent("removelayer");
     },
 
+    /**
+    * @returns The number of layers attached to the map.
+    * @type int
+    */
+    getNumLayers: function () {
+        return this.layers.length;
+    },
+
+    /** 
+    * @returns The current (zero-based) index of the given layer in the map's
+    *     layer stack. Returns -1 if the layer isn't on the map.
+    *
+    * @param {OpenLayers.Layer} layer
+    * @type int
+    */
+    getLayerIndex: function (layer) {
+        return OpenLayers.Util.indexOf(this.layers, layer);
+    },
+    
+    /** Move the given layer to the specified (zero-based) index in the layer
+    *     list, changing its z-index in the map display. Use
+    *     map.getLayerIndex() to find out the current index of a layer. Note
+    *     that this cannot (or at least should not) be effectively used to
+    *     raise base layers above overlays.
+    *
+    * @param {OpenLayers.Layer} layer
+    * @param {int} idx
+    */
+    setLayerIndex: function (layer, idx) {
+        var base = this.getLayerIndex(layer);
+        if (idx < 0) 
+            idx = 0;
+        else if (idx > this.layers.length)
+            idx = this.layers.length;
+        if (base != idx) {
+            this.layers.splice(base, 1);
+            this.layers.splice(idx, 0, layer);
+            for (var i = 0; i < this.layers.length; i++)
+                this.setLayerZIndex(this.layers[i], i);
+            this.events.triggerEvent("changelayer");
+        }
+    },
+
+    /** Change the index of the given layer by delta. If delta is positive, 
+    *     the layer is moved up the map's layer stack; if delta is negative,
+    *     the layer is moved down.  Again, note that this cannot (or at least
+    *     should not) be effectively used to raise base layers above overlays.
+    *
+    * @param {OpenLayers.Layer} layer
+    * @param {int} idx
+    */
+    raiseLayer: function (layer, delta) {
+        var idx = this.getLayerIndex(layer) + delta;
+        this.setLayerIndex(layer, idx);
+    },
+    
     /** Allows user to specify one of the currently-loaded layers as the Map's
      *   new base layer.
      * 

tests/test_Map.html

@@ -249,7 +249,46 @@
 
     }
 
-    function test_088_Map_setCenter(t) {
+    function test_12_Map_moveLayer (t) {
+        t.plan(10);
+        var ct  = 0;
+        map = new OpenLayers.Map($('map'));
+        var wmslayer = new OpenLayers.Layer.WMS('Test Layer', 
+                    "http://octo.metacarta.com/cgi-bin/mapserv", 
+                    {map: '/mapdata/vmap_wms.map', layers: 'basic', format: 'image/jpeg'}, 
+                    {maxExtent: new OpenLayers.Bounds(33861, 717605, 330846, 1019656), maxResolution: 296985/1024, projection:"EPSG:2805" } );
+
+        var wmslayer2 = new OpenLayers.Layer.WMS('Test Layer2', 
+                    "http://octo.metacarta.com/cgi-bin/mapserv", 
+                    {map: '/mapdata/vmap_wms.map', layers: 'basic', format: 'image/jpeg'}, 
+                    {maxExtent: new OpenLayers.Bounds(33861, 717605, 330846, 1019656), maxResolution: 296985/1024, projection:"EPSG:2805" } );
+
+        var wmslayer3 = new OpenLayers.Layer.WMS('Test Layer2', 
+                    "http://octo.metacarta.com/cgi-bin/mapserv", 
+                    {map: '/mapdata/vmap_wms.map', layers: 'basic', format: 'image/jpeg'}, 
+                    {maxExtent: new OpenLayers.Bounds(33861, 717605, 330846, 1019656), maxResolution: 296985/1024, projection:"EPSG:2805" } );
+
+        map.addLayers([wmslayer, wmslayer2, wmslayer3]);
+        map.events.register("changelayer", map, function (e) { ct++; });
+        t.eq( map.getNumLayers(), 3, "getNumLayers returns the number of layers" );
+        t.eq( map.getLayerIndex(wmslayer3), 2, "getLayerIndex returns the right index" );
+        map.raiseLayer(wmslayer3, 1);
+        t.eq( map.getLayerIndex(wmslayer3), 2, "can't moveLayer up past the top of the stack" );
+        map.raiseLayer(wmslayer, -1);
+        t.eq( map.getLayerIndex(wmslayer), 0, "can't moveLayer down past the bottom of the stack" );
+        map.raiseLayer(wmslayer3, -1);
+        t.eq( map.getLayerIndex(wmslayer3), 1, "can moveLayer down from the top" );
+        t.eq( parseInt(wmslayer3.div.style.zIndex), map.Z_INDEX_BASE['BaseLayer'] + 5,
+            "layer div has the right zIndex after moving down" );
+        map.raiseLayer(wmslayer, 2);
+        t.eq( map.getLayerIndex(wmslayer), 2, "can moveLayer up from the bottom" );
+        t.eq( parseInt(wmslayer.div.style.zIndex), map.Z_INDEX_BASE['BaseLayer'] + 2 * 5,
+            "layer div has the right zIndex after moving up" );
+        t.eq( map.getLayerIndex(wmslayer3), 0, "top layer is now on the bottom" );
+        t.eq( ct, 3, "raiseLayer triggered changelayer the right # of times" );
+    }
+    
+    function test_08_Map_setCenter(t) {
         t.plan(1);
         map = new OpenLayers.Map($('map'));
         var baseLayer = new OpenLayers.Layer.WMS("Test Layer",