pushing preview for import

preview/js/utils/UserSettings.js

@@ -0,0 +1,76 @@
+(function () {
+  var ns = $.namespace("pskl");
+
+  ns.UserSettings = {
+
+    SHOW_GRID : 'SHOW_GRID',
+    CANVAS_BACKGROUND : 'CANVAS_BACKGROUND',
+
+    KEY_TO_DEFAULT_VALUE_MAP_ : {
+      'SHOW_GRID' : false,
+      'CANVAS_BACKGROUND' : 'medium-canvas-background'
+    },
+
+    /**
+     * @private
+     */
+    cache_ : {},
+
+    /**
+     * Static method to access a user defined settings value ot its default
+     * value if not defined yet.
+     */
+    get : function (key) {
+      this.checkKeyValidity_(key);
+      if (!(key in this.cache_)) {
+        this.cache_[key] =
+          this.readFromLocalStorage_(key) || this.readFromDefaults_(key);
+      }
+      return this.cache_[key];
+    },
+
+    set : function (key, value) {
+      this.checkKeyValidity_(key);
+      this.cache_[key] = value;
+      this.writeToLocalStorage_(key, value);
+
+      $.publish(Events.USER_SETTINGS_CHANGED, [key, value]);
+    },
+
+    /**
+     * @private
+     */
+    readFromLocalStorage_ : function(key) {
+      var value = window.localStorage[key];
+      if (typeof value != "undefined") {
+        value = JSON.parse(value);
+      }
+      return value;
+    },
+
+    /**
+     * @private
+     */
+    writeToLocalStorage_ : function(key, value) {
+      // TODO(grosbouddha): Catch storage exception here.
+      window.localStorage[key] = JSON.stringify(value);
+    },
+
+    /**
+     * @private
+     */
+    readFromDefaults_ : function (key) {
+      return this.KEY_TO_DEFAULT_VALUE_MAP_[key];
+    },
+
+    /**
+     * @private
+     */
+    checkKeyValidity_ : function(key) {
+      if(!(key in this.KEY_TO_DEFAULT_VALUE_MAP_)) {
+        // TODO(grosbouddha): Define error catching strategy and throw exception from here.
+        console.log("UserSettings key <"+ key +"> not find in supported keys.");
+      }
+    }
+  };
+})();