Listen for property changes in layer group

This avoids a future bug when the ol.ObjectEventType.CHANGE value becomes something different than the goog.events.EventType.CHANGE value.

src/ol/layer/layergroup.js

@@ -3,13 +3,13 @@ goog.provide('ol.layer.Group');
 goog.require('goog.array');
 goog.require('goog.asserts');
 goog.require('goog.events');
-goog.require('goog.events.EventType');
 goog.require('goog.math');
 goog.require('goog.object');
 goog.require('ol.Collection');
 goog.require('ol.CollectionEvent');
 goog.require('ol.CollectionEventType');
 goog.require('ol.Object');
+goog.require('ol.ObjectEventType');
 goog.require('ol.layer.Base');
 goog.require('ol.source.State');
 
@@ -104,7 +104,7 @@ ol.layer.Group.prototype.handleLayersChanged_ = function(event) {
     for (i = 0, ii = layersArray.length; i < ii; i++) {
       layer = layersArray[i];
       this.listenerKeys_[goog.getUid(layer).toString()] =
-          goog.events.listen(layer, goog.events.EventType.CHANGE,
+          goog.events.listen(layer, ol.ObjectEventType.CHANGE,
               this.handleLayerChange_, false, this);
     }
   }
@@ -120,7 +120,7 @@ ol.layer.Group.prototype.handleLayersChanged_ = function(event) {
 ol.layer.Group.prototype.handleLayersAdd_ = function(collectionEvent) {
   var layer = /** @type {ol.layer.Base} */ (collectionEvent.getElement());
   this.listenerKeys_[goog.getUid(layer).toString()] = goog.events.listen(
-      layer, goog.events.EventType.CHANGE, this.handleLayerChange_, false,
+      layer, ol.ObjectEventType.CHANGE, this.handleLayerChange_, false,
       this);
   this.dispatchChangeEvent();
 };

test/spec/ol/layer/layergroup.test.js

@@ -63,7 +63,7 @@ describe('ol.layer.Group', function() {
 
   });
 
-  describe('change event', function() {
+  describe('generic change event', function() {
 
     var layer, group, listener;
     beforeEach(function() {
@@ -84,14 +84,14 @@ describe('ol.layer.Group', function() {
     });
 
     it('is dispatched by the group when layer opacity changes', function() {
-      group.on(ol.ObjectEventType.CHANGE, listener);
+      group.on(goog.events.EventType.CHANGE, listener);
 
       layer.setOpacity(0.5);
       expect(listener.calledOnce).to.be(true);
     });
 
     it('is dispatched by the group when layer visibility changes', function() {
-      group.on(ol.ObjectEventType.CHANGE, listener);
+      group.on(goog.events.EventType.CHANGE, listener);
 
       layer.setVisible(false);
       expect(listener.callCount).to.be(1);
@@ -102,6 +102,45 @@ describe('ol.layer.Group', function() {
 
   });
 
+  describe('property change event', function() {
+
+    var layer, group, listener;
+    beforeEach(function() {
+      layer = new ol.layer.Layer({
+        source: new ol.source.Source({
+          projection: 'EPSG:4326'
+        })
+      });
+      group = new ol.layer.Group({
+        layers: [layer]
+      });
+      listener = sinon.spy();
+    });
+
+    afterEach(function() {
+      goog.dispose(group);
+      goog.dispose(layer);
+    });
+
+    it('is dispatched by the group when group opacity changes', function() {
+      group.on(ol.ObjectEventType.CHANGE, listener);
+
+      group.setOpacity(0.5);
+      expect(listener.calledOnce).to.be(true);
+    });
+
+    it('is dispatched by the group when group visibility changes', function() {
+      group.on(ol.ObjectEventType.CHANGE, listener);
+
+      group.setVisible(false);
+      expect(listener.callCount).to.be(1);
+
+      group.setVisible(true);
+      expect(listener.callCount).to.be(2);
+    });
+
+  });
+
   describe('constructor (options)', function() {
 
     it('accepts options', function() {
@@ -352,6 +391,7 @@ describe('ol.layer.Group', function() {
 });
 
 goog.require('goog.dispose');
+goog.require('goog.events.EventType');
 goog.require('ol.ObjectEventType');
 goog.require('ol.layer.Layer');
 goog.require('ol.layer.Group');