From 88da6da3a7bbea5d30e17861e1e683b4a9a68656 Mon Sep 17 00:00:00 2001
From: Bruno Binet <bruno.binet@gmail.com>
Date: Mon, 12 Aug 2013 11:51:42 +0200
Subject: [PATCH] Trigger CHANGE event only when required

For example only when layer is both ready and visible.
---
 src/ol/layer/layerbase.js  | 19 +++++++++++++++++--
 src/ol/layer/layergroup.js | 18 ++++++++++++++++++
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/src/ol/layer/layerbase.js b/src/ol/layer/layerbase.js
index 1d154fd40a..3273e744be 100644
--- a/src/ol/layer/layerbase.js
+++ b/src/ol/layer/layerbase.js
@@ -67,11 +67,14 @@ ol.layer.LayerBase = function(options) {
     ol.Object.getChangeEventType(ol.layer.LayerProperty.HUE),
     ol.Object.getChangeEventType(ol.layer.LayerProperty.OPACITY),
     ol.Object.getChangeEventType(ol.layer.LayerProperty.SATURATION),
-    ol.Object.getChangeEventType(ol.layer.LayerProperty.VISIBLE),
     goog.events.EventType.LOAD
   ],
   this.handleLayerChange, false, this);
 
+  goog.events.listen(this,
+      ol.Object.getChangeEventType(ol.layer.LayerProperty.VISIBLE),
+      this.handleLayerVisibleChange, false, this);
+
 };
 goog.inherits(ol.layer.LayerBase, ol.Object);
 
@@ -204,7 +207,19 @@ goog.exportProperty(
  * @protected
  */
 ol.layer.LayerBase.prototype.handleLayerChange = function() {
-  this.dispatchChangeEvent();
+  if (this.getVisible() && this.isReady()) {
+    this.dispatchChangeEvent();
+  }
+};
+
+
+/**
+ * @protected
+ */
+ol.layer.LayerBase.prototype.handleLayerVisibleChange = function() {
+  if (this.isReady()) {
+    this.dispatchChangeEvent();
+  }
 };
 
 
diff --git a/src/ol/layer/layergroup.js b/src/ol/layer/layergroup.js
index 163500305f..b93c0e40b2 100644
--- a/src/ol/layer/layergroup.js
+++ b/src/ol/layer/layergroup.js
@@ -66,6 +66,24 @@ ol.layer.LayerGroup = function(opt_options) {
 goog.inherits(ol.layer.LayerGroup, ol.layer.LayerBase);
 
 
+/**
+ * @inheritDoc
+ */
+ol.layer.LayerGroup.prototype.handleLayerChange = function() {
+  if (this.getVisible()) {
+    this.dispatchChangeEvent();
+  }
+};
+
+
+/**
+ * @inheritDoc
+ */
+ol.layer.LayerGroup.prototype.handleLayerVisibleChange = function() {
+  this.dispatchChangeEvent();
+};
+
+
 /**
  * @param {goog.events.Event} event Event.
  * @private