Optimize component and event creation, add cache for interests, optimize scroll

druid/event.lua

@@ -13,7 +13,7 @@ local DruidEvent = class("druid.event")
 -- @tparam DruidEvent self @{DruidEvent}
 -- @tparam function initial_callback Subscribe the callback on new event, if callback exist
 function DruidEvent.initialize(self, initial_callback)
-	self._callbacks = {}
+	self._callbacks = nil -- initialize later
 
 	if initial_callback then
 		self:subscribe(initial_callback)
@@ -29,6 +29,7 @@ function DruidEvent.subscribe(self, callback, context)
 	assert(type(self) == "table", "You should subscribe to event with : syntax")
 	assert(type(callback) == "function", "Callback should be function")
 
+	self._callbacks = self._callbacks or {}
 	table.insert(self._callbacks, {
 		callback = callback,
 		context = context
@@ -43,6 +44,10 @@ end
 -- @tparam function callback Callback itself
 -- @tparam table context Additional context as first param to callback call
 function DruidEvent.unsubscribe(self, callback, context)
+	if not self._callbacks then
+		return
+	end
+
 	for index, callback_info in ipairs(self._callbacks) do
 		if callback_info.callback == callback and callback_info.context == context then
 			table.remove(self._callbacks, index)
@@ -56,6 +61,9 @@ end
 -- @tparam DruidEvent self @{DruidEvent}
 -- @treturn bool True if event have handlers
 function DruidEvent.is_exist(self)
+	if not self._callbacks then
+		return false
+	end
 	return #self._callbacks > 0
 end
 
@@ -63,7 +71,7 @@ end
 --- Clear the all event handlers
 -- @tparam DruidEvent self @{DruidEvent}
 function DruidEvent.clear(self)
-	self._callbacks = {}
+	self._callbacks = nil
 end
 
 
@@ -71,6 +79,10 @@ end
 -- @tparam DruidEvent self @{DruidEvent}
 -- @tparam any ... All event params
 function DruidEvent.trigger(self, ...)
+	if not self._callbacks then
+		return false
+	end
+
 	for index, callback_info in ipairs(self._callbacks) do
 		if callback_info.context then
 			callback_info.callback(callback_info.context, ...)