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gaia/apps/system/lockscreen/js/source/setting_source.js

@@ -0,0 +1,52 @@
+/* global SourceEvent */
+'use strict';
+
+/**
+ * Event source for Stream. One Stream can collect events from multiple
+ * sources, which pass different native events (not only DOM events)
+ * to Stream.
+ **/
+(function(exports) {
+  var SettingSource = function(configs) {
+    this.configs = {
+      settings: configs.settings || []
+    };
+    this._collector = navigator.mozSettings.addObserver;
+    this._decollector = navigator.mozSettings.removeObserver;
+    this._forwardTo = null;
+    // Some API you just can't bind it with the object,
+    // but a function.
+    this.onchange = this.onchange.bind(this);
+  };
+
+  SettingSource.prototype.start = function(forwardTo) {
+    this.configs.settings.forEach((key) => {
+      this._collector(key, this.onchange);
+    });
+    this._forwardTo = forwardTo;
+    return this;
+  };
+
+  SettingSource.prototype.stop = function() {
+    this._forwardTo = null;
+    this.configs.settings.forEach((key) => {
+      this._decollector(key, this.onchange);
+    });
+    return this;
+  };
+
+  /**
+   * For forwarding to the target.
+   * Would transform the original 'settingName' and 'settingValue' pair as
+   * 'type' and 'detail', as the event formant.
+   */
+  SettingSource.prototype.onchange = function(change) {
+    if (this._forwardTo) {
+      this._forwardTo(
+        new SourceEvent(change.settingName, change.settingValue));
+    }
+  };
+
+  exports.SettingSource = SettingSource;
+})(window);
+