After r10021 we lost the ability to set the opacity of a Google layer. This makes layer.setOpacity work again by setting the opactiy of the shared GMap container. r=bartvde (pullup #2562)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@10174 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/Google.js

@@ -263,7 +263,10 @@ OpenLayers.Layer.Google = OpenLayers.Class(
      */
     setVisibility: function(visible) {
         this.setGMapVisibility(visible);
+        // sharing a map container, opacity has to be set per layer
+        var opacity = this.opacity == null ? 1 : this.opacity;
         OpenLayers.Layer.EventPane.prototype.setVisibility.apply(this, arguments);
+        this.setOpacity(opacity);
     },
     
     /**
@@ -303,6 +306,33 @@ OpenLayers.Layer.Google = OpenLayers.Class(
         }
     },
     
+    /**
+     * APIMethod: setOpacity
+     * Sets the opacity for the entire layer (all images)
+     * 
+     * Parameter:
+     * opacity - {Float}
+     */
+    setOpacity: function(opacity) {
+        if (opacity !== this.opacity) {
+            if (this.map != null) {
+                this.map.events.triggerEvent("changelayer", {
+                    layer: this,
+                    property: "opacity"
+                });
+            }
+            this.opacity = opacity;
+        }
+        // Though this layer's opacity may not change, we're sharing a container
+        // and need to update the opacity for the entire container.
+        if (this.getVisibility()) {
+            var container = this.mapObject.getContainer();
+            OpenLayers.Util.modifyDOMElement(
+                container, null, null, null, null, null, null, opacity
+            );
+        }
+    },
+
     /**
      * APIMethod: destroy
      * Clean up this layer.

tests/Layer/Google.html

@@ -236,6 +236,56 @@
         }
     }
     
+    function test_setOpacity(t) {
+        
+        t.plan(6);
+        
+        var map = new OpenLayers.Map("map");
+        var gmap = new OpenLayers.Layer.Google(
+            "Google Streets", // the default
+            {numZoomLevels: 20}
+        );
+        var ghyb = new OpenLayers.Layer.Google(
+            "Google Hybrid",
+            {type: G_HYBRID_MAP, numZoomLevels: 20}
+        );
+        var gsat = new OpenLayers.Layer.Google(
+            "Google Satellite",
+            {type: G_SATELLITE_MAP, numZoomLevels: 22}
+        );
+        map.addLayers([gmap, ghyb, gsat]);
+        map.zoomToMaxExtent();
+        
+        var container = map.baseLayer.mapObject.getContainer();
+        var opacityCheck = function(opacity) {
+            var style = container.style;
+            var current = style.opacity === "" ? 1 : parseFloat(style.opacity);
+            if (style.filter && !style.opacity) {
+                current = Number(style.filter.replace(/alpha\(opacity=(.+?)\)/, "$1"));
+            }
+            return (current === opacity);
+        };
+        
+        gmap.setOpacity(0.5);
+        t.ok(opacityCheck(0.5), "container opacity set for visible layer");
+        
+        ghyb.setOpacity(0.75);
+        t.ok(opacityCheck(0.5), "container opacity not changed if layer not visible");
+        map.setBaseLayer(ghyb);
+        t.ok(opacityCheck(0.75), "container opacity changed to 0.75 when layer becomes visible");
+        
+        map.setBaseLayer(gsat);
+        t.ok(opacityCheck(1), "container opacity set to 1 by default");
+        gsat.setOpacity(0.25);
+        t.ok(opacityCheck(0.25), "container opacity changed to 0.25 for visible layer");
+        
+        map.setBaseLayer(gmap);
+        t.ok(opacityCheck(0.5), "container opacity set to layer opacity");
+        
+        map.destroy();
+        
+    }
+
     function test_Layer_Google_setGMapVisibility(t) {
         if(validkey) {
             t.plan(4);