Add aa's Event class to our javascript bindings and use it in our extension

message passing API.
Review URL: http://codereview.chromium.org/62069

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@13371 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 120 insertions, 0 deletions

diff --git a/chrome/renderer/resources/event_bindings.js b/chrome/renderer/resources/event_bindings.js
new file mode 100644
index 0000000..de5b3a9
--- /dev/null
+++ b/chrome/renderer/resources/event_bindings.js
@@ -0,0 +1,120 @@
+var chromium = chromium || {};
+(function () {
+  native function AttachEvent(eventName);
+  native function DetachEvent(eventName);
+
+  // Event object.  If opt_eventName is provided, this object represents
+  // the unique instance of that named event, and dispatching an event
+  // with that name will route through this object's listeners.
+  //
+  // Example:
+  //   chromium.ontabchanged = new Event('tabchanged');
+  //   chromium.ontabchanged.addListener(function(data) { alert(data); });
+  //   chromium.Event.dispatch_('tabchanged', 'hi');
+  // will result in an alert dialog that says 'hi'.
+  chromium.Event = function(opt_eventName) {
+    this.eventName_ = opt_eventName;
+    this.listeners_ = [];
+  };
+
+  // A map of event names to the event object that is registered to that name.
+  chromium.Event.attached_ = {};
+
+  // Dispatches a named event with the given JSON data, which is deserialized
+  // before dispatch.
+  chromium.Event.dispatchJSON_ = function(name, data) {
+    if (chromium.Event.attached_[name]) {
+      if (data) {
+        data = chromium.json.deserialize_(data);
+      }
+      chromium.Event.attached_[name].dispatch_(data);
+    }
+  };
+
+  // Dispatches a named event with the given object data.
+  chromium.Event.dispatch_ = function(name, data) {
+    if (chromium.Event.attached_[name]) {
+      chromium.Event.attached_[name].dispatch(data);
+    }
+  };
+
+  // Registers a callback to be called when this event is dispatched.
+  chromium.Event.prototype.addListener = function(cb) {
+    this.listeners_.push(cb);
+    if (this.listeners_.length == 1) {
+      this.attach_();
+    }
+  };
+
+  // Unregisters a callback.
+  chromium.Event.prototype.removeListener = function(cb) {
+    var idx = this.findListener_(cb);
+    if (idx == -1) {
+      return;
+    }
+
+    this.listeners_.splice(idx, 1);
+    if (this.listeners_.length == 0) {
+      this.detach_();
+    }
+  };
+
+  // Test if the given callback is registered for this event.
+  chromium.Event.prototype.hasListener = function(cb) {
+    return this.findListeners_(cb) > -1;
+  };
+
+  // Returns the index of the given callback if registered, or -1 if not
+  // found.
+  chromium.Event.prototype.findListener_ = function(cb) {
+    for (var i = 0; i < this.listeners_.length; i++) {
+      if (this.listeners_[i] == cb) {
+        return i;
+      }
+    }
+
+    return -1;
+  };
+
+  // Dispatches this event object to all listeners, passing all supplied
+  // arguments to this function each listener.
+  chromium.Event.prototype.dispatch = function(varargs) {
+    var args = Array.prototype.slice.call(arguments);
+    for (var i = 0; i < this.listeners_.length; i++) {
+      try {
+        this.listeners_[i].apply(null, args);
+      } catch (e) {
+        console.error(e);
+      }
+    }
+  };
+
+  // Attaches this event object to its name.  Only one object can have a given
+  // name.
+  chromium.Event.prototype.attach_ = function() {
+    AttachEvent(this.eventName_);
+    if (!this.eventName_)
+      return;
+
+    if (chromium.Event.attached_[this.eventName_]) {
+      throw new Error("chromium.Event '" + this.eventName_ +
+                      "' is already attached.");
+    }
+
+    chromium.Event.attached_[this.eventName_] = this;
+  };
+
+  // Detaches this event object from its name.
+  chromium.Event.prototype.detach_ = function() {
+    DetachEvent(this.eventName_);
+    if (!this.eventName_)
+      return;
+
+    if (!chromium.Event.attached_[this.eventName_]) {
+      throw new Error("chromium.Event '" + this.eventName_ +
+                      "' is not attached.");
+    }
+
+    delete chromium.Event.attached_[this.eventName_];
+  };
+})();