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https://issues.apache.org/jira/browse/FLEX-33740?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13773041#comment-13773041
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David Lantier commented on FLEX-33740:
--------------------------------------
Hello Justin, I'm coming back with news.
First, I've implemented an override as proposed first (named
"removedFromStageOverride") and implemented in 2 classes, one written in MXML,
an "s:Vgroup" composed by a lot of components (named ModelView, about 80
children added dynamically), another written in AS3 class that extends
NavigatorContent. For the test, each "NavigatorContent" has a ModelView as
child and a TabNavigator for parent.
Then, I've programmed 100 addChild of NavigatorContent, which created also 100
ModelView, followed by 100 removeChild (that remove also the 100 ModelView as
they quit the stage), then I've repeated this cycle a lot to take times and
memory.
After that, I've done the same tests, but based on events, not on override.
And, you are right … performances are the same between override and listening
events (about 28 seconds for one cycle with override, 29 seconds with events,
not significant for me). Also, I've discovered that it was not a good idea to
override removedFromStage, because we do not take advantage of the event flow
manager (we can be called twice by ovveride, when we receive only one event).
For all these reasons, I think that my request … is a bad request ;-) We all
should rely on event flow to manage UIComponent livecycle (added/removed from
stage). I was convinced that override could be simpler and faster than event
listening, but it is not.
Thanks a lot for attention and your answers!
Here, for example, the helper class I use in composition to manage live cycle
events, with an interface (IwhpGuiLivecycle) for callbacks.
private function waitCreationComplete( wdo:DisplayObject ):void {
CONFIG::debugging {
if( ! ( wdo is IWhpGuiLivecycle ) )
throw new Error( wdo + " is not IWhpGuiLivecycle" );
}
wdo.addEventListener( FlexEvent.CREATION_COMPLETE, wdo_creationCompleteHandler
);
}
// ===== handle events
private function wdo_creationCompleteHandler( event:FlexEvent=null ):void {
var ect:Object = event.currentTarget;
ect.removeEventListener( FlexEvent.CREATION_COMPLETE,
wdo_creationCompleteHandler );
ect.addEventListener( FlexEvent.REMOVE, wdo_removedHandler );
ect.addEventListener( Event.REMOVED_FROM_STAGE, wdo_removedFromStageHandler );
IWhpGuiLivecycle( ect ).thisStageOn( true );
}
private function wdo_addedToStageHandler( event:Event=null ):void {
var ect:Object = event.currentTarget;
ect.removeEventListener( Event.ADDED_TO_STAGE, wdo_addedToStageHandler );
ect.addEventListener( Event.REMOVED_FROM_STAGE, wdo_removedFromStageHandler );
ect.addEventListener( FlexEvent.REMOVE, wdo_removedHandler );
IWhpGuiLivecycle( ect ).thisStageOn( false );
}
private function wdo_removedHandler( event:Event=null ):void {
var ect:Object = event.currentTarget;
ect.removeEventListener( FlexEvent.REMOVE, wdo_removedHandler );
_isRemoved = true;
}
private function wdo_removedFromStageHandler( event:Event=null ):void {
var ect:Object = event.currentTarget;
ect.removeEventListener( Event.REMOVED_FROM_STAGE, wdo_removedFromStageHandler
);
ect.addEventListener( Event.ADDED_TO_STAGE, wdo_addedToStageHandler );
IWhpGuiLivecycle( ect ).thisStageOff( _isRemoved );
_isRemoved = false;
}
> Change UIComponent function removedFromStageHandler from private to protected
> to allow override
> -----------------------------------------------------------------------------------------------
>
> Key: FLEX-33740
> URL: https://issues.apache.org/jira/browse/FLEX-33740
> Project: Apache Flex
> Issue Type: Improvement
> Components: .Unspecified - Framework
> Affects Versions: Apache Flex 4.10.0
> Environment: Gui framework
> Reporter: David Lantier
> Assignee: Justin Mclean
> Labels: features, performance
> Fix For: Apache Flex 4.11.0
>
> Original Estimate: 24h
> Remaining Estimate: 24h
>
> It would be more safe and faster if it was possible to override the function
> UIComponent::removedFromStageHandler (and also, remove) instead to have to
> add and remove events listeners for those who extends UI classes.
> Have to check if new proposed method name "removedFromStage" not used by any
> component, or choose another.
> Example:
> private function removedFromStageHandler(event:Event):void
> {
> _systemManagerDirty = true;
> removedFromStage(); // proposition: add this call
> }
> // proposition: new function protected, dedicated to override
> /** Override this allow to be called when this is removing from stage. Avoids
> to have to listen REMOVED_FROM_STAGE event. */
> protected function removedFromStage():void {}
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