Merge pull request #4064 from fredj/lazy_ol.style.defaultStyleFunction

Use a private variable to cache the default style array

src/ol/style/style.js

@@ -239,12 +239,25 @@ ol.style.createStyleFunction = function(obj) {
 };
 
 
+/**
+ * @type {Array.<ol.style.Style>}
+ * @private
+ */
+ol.style.defaultStyle_ = null;
+
+
 /**
  * @param {ol.Feature} feature Feature.
  * @param {number} resolution Resolution.
  * @return {Array.<ol.style.Style>} Style.
  */
 ol.style.defaultStyleFunction = function(feature, resolution) {
+  // We don't use an immediately-invoked function
+  // and a closure so we don't get an error at script evaluation time in
+  // browsers that do not support Canvas. (ol.style.Circle does
+  // canvas.getContext('2d') at construction time, which will cause an.error
+  // in such browsers.)
+  if (goog.isNull(ol.style.defaultStyle_)) {
     var fill = new ol.style.Fill({
       color: 'rgba(255,255,255,0.4)'
     });
@@ -252,7 +265,7 @@ ol.style.defaultStyleFunction = function(feature, resolution) {
       color: '#3399CC',
       width: 1.25
     });
-  var styles = [
+    ol.style.defaultStyle_ = [
       new ol.style.Style({
         image: new ol.style.Circle({
           fill: fill,
@@ -263,24 +276,8 @@ ol.style.defaultStyleFunction = function(feature, resolution) {
         stroke: stroke
       })
     ];
-
+  }
-  // Now that we've run it the first time, replace the function with
+  return ol.style.defaultStyle_;
-  // a constant version. We don't use an immediately-invoked function
-  // and a closure so we don't get an error at script evaluation time in
-  // browsers that do not support Canvas. (ol.style.Circle does
-  // canvas.getContext('2d') at construction time, which will cause an.error
-  // in such browsers.)
-
-  /**
-   * @param {ol.Feature} feature Feature.
-   * @param {number} resolution Resolution.
-   * @return {Array.<ol.style.Style>} Style.
-   */
-  ol.style.defaultStyleFunction = function(feature, resolution) {
-    return styles;
-  };
-
-  return styles;
 };