[IMP] web: introduces event bubbling in widgets

This commit adds event bubbling in the event dispatcher mixin (which
inherits from parentedmixins).  To do this, it introduces a new small
class 'OdooEvent', which register the target and if the event is stopped.

Also, widgets have a new 'custom_events' dictionary to easily register
callbacks like the event dictionary.

addons/web/static/src/js/framework/mixins.js

@@ -114,6 +114,22 @@ var ParentedMixin = {
     },
 };
 
+function OdooEvent (target, name, data) {
+    this.target = target;
+    this.name = name;
+    this.data = Object.create(null);
+    _.extend(this.data, data);
+    this.stopped = false;
+}
+
+OdooEvent.prototype.stop_propagation = function () {
+    this.stopped = true;
+};
+
+OdooEvent.prototype.is_stopped = function () {
+    return this.stopped;
+};
+
 /**
  * Backbone's events. Do not ever use it directly, use EventDispatcherMixin instead.
  *
@@ -256,6 +272,16 @@ var EventDispatcherMixin = _.extend({}, ParentedMixin, {
         this.__edispatcherEvents.trigger.apply(this.__edispatcherEvents, arguments);
         return this;
     },
+    trigger_up: function(name, info) {
+        var event = new OdooEvent(this, name, info);
+        this._trigger_up(event);
+    },
+    _trigger_up: function(event) {
+        this.__edispatcherEvents.trigger(event.name, event);
+        if (!event.is_stopped() && (parent = this.getParent())) {
+            parent._trigger_up(event);
+        }
+    },
     destroy: function() {
         var self = this;
         _.each(this.__edispatcherRegisteredEvents, function(event) {

addons/web/static/src/js/framework/widget.js

@@ -64,6 +64,7 @@ var Widget = core.Class.extend(mixins.PropertiesMixin, {
     className: null,
     attributes: {},
     events: {},
+    custom_events: {},
     /**
      * The name of the QWeb template that will be used for rendering. Must be
      * redefined in subclasses or the default render() method can not be used.
@@ -94,6 +95,7 @@ var Widget = core.Class.extend(mixins.PropertiesMixin, {
         }
         // FIXME: this should not be
         this.setElement(this._make_descriptive());
+        this.delegateCustomEvents();
     },
     /**
      * Method called between init and start. Performs asynchronous calls required by start.
@@ -303,6 +305,21 @@ var Widget = core.Class.extend(mixins.PropertiesMixin, {
             }
         }
     },
+    delegateCustomEvents: function () {
+        if (_.isEmpty(this.custom_events)) { return; }
+        for (var key in this.custom_events) {
+            if (!this.custom_events.hasOwnProperty(key)) { continue; }
+
+            var method = this.proxy(this.custom_events[key]);
+            this.on(key, this, wrap_handler(method));
+        }
+        function wrap_handler(callback) {
+            return function (event) {
+                event.stop_propagation();
+                callback(event);
+            };
+        }
+    },
     undelegateEvents: function () {
         this.$el.off('.widget_events');
     },