Actionscript 3: Entire event dispatching becomes unusable - actionscript-3

Question

I'm working on something similar to the Angry Birds "rollout" for options, etc., but I'm running into a fairly substantial problem.
The rollout itself is just a toggle button, with several other buttons added to the display list that move when you touch the toggle button. Each of these buttons is a class that extends Sprite and contains individual methods for touch events, begin, end and out. When these buttons get initialized (NOT instantiated), the touch begin listener is added. Something like this:
public function Initialize():void
{
this.addEventListener(TouchEvent.TOUCH_BEGIN, OnTouchBegin, false, int.MAX_VALUE);
}
private function OnTouchBegin(e:TouchEvent):void
{
this.removeEventListener(TouchEvent.TOUCH_BEGIN, OnTouchBegin);
this.addEventListener(TouchEvent.TOUCH_END, OnTouchRelease, false, int.MAX_VALUE);
this.addEventListener(TouchEvent.TOUCH_OUT, OnTouchOut, false, int.MAX_VALUE);
}
private function OnTouchRelease(e:TouchEvent):void
{
this.addEventListener(TouchEvent.TOUCH_BEGIN, OnTouchBegin, false, int.MAX_VALUE);
this.removeEventListener(TouchEvent.TOUCH_END, OnTouchRelease);
this.removeEventListener(TouchEvent.TOUCH_OUT, OnTouchOut);
}
private function OnTouchOut(e:TouchEvent):void
{
this.addEventListener(TouchEvent.TOUCH_BEGIN, OnTouchBegin, false, int.MAX_VALUE);
this.removeEventListener(TouchEvent.TOUCH_END, OnTouchRelease);
this.removeEventListener(TouchEvent.TOUCH_OUT, OnTouchOut);
}
Then, when these buttons get hidden from the screen, a method is called to remove any of the listeners that are currently active on them:
public function Deactivate():void
{
this.removeEventListener(TouchEvent.TOUCH_OUT, OnTouchOut);
this.removeEventListener(TouchEvent.TOUCH_END, OnTouchRelease);
this.removeEventListener(TouchEvent.TOUCH_BEGIN, OnTouchBegin);
}
This is just for the standard button functionality (up/down texture and sound), on top of this, when I make the game, in my rollout class, I have an additional method that will add another event listener for custom logic that should occur when the button is touched (the button itself is created elsewhere).
public function AddRolloutButton(listener:Function):void
{
if (listener != null)
{
_buttons[index].addEventListener(TouchEvent.TOUCH_BEGIN, listener);
}
The buttons in the rollout itself are removed from the display list until they are to be shown. When the rollout is closed, the buttons are deactivated (removed from display list and the 3 button listeners within the button class are removed).
Everything works perfectly fine the very first time I open and close the rollout. After that, the event dispatching system just inexplicably dies. Every single InteractiveObject on the screen, regardless of position or type, becomes unusable. I traced out whether or not the listeners were still there on the rollout toggle button, and it was. I also confirmed that the rollout button itself was the only thing on the display list.
What I've noticed is that if I comment out the listener removal in the deactivate method of the button for the touch begin listener, or pass in null for the listener method in the AddRolloutButton method, everything works just fine. The issue seems to stem from having multiple listeners of the same type on the rollout buttons, and then removing one or all of them.
If anyone has any ideas of just what is going on, that would be very helpful. I was under the impression that adding multiple listeners of the same type to an InteractiveObject was perfectly valid.
UPDATE:
It appears that only TouchEvents get broken by this issue I'm having. I just tried using a mouse click listener on the stage after opening and closing the rollout, and that still works. So, only touch events are getting broken, if that helps at all.

Answer 1

Seems like there is something going wrong in your AddRolloutButton method. Are you sure you are assigning the correct listener function?
In your example the listener:Function argument should be equal to _buttons[index]. OnTouchBegin.
Or, since whatever class that owns the AddRolloutButton method seems to be in control of the buttons, you could potentially scrap the listener argument altogether since you know what method that needs to be triggered.
For example like this:
public function AddRolloutButton():void {
var currentButton:MyButtonClass = _buttons[index] as MyButtonClass;
currentButton.addEventListener(TouchEvent.TOUCH_BEGIN, currentButton.OnTouchBegin);
[...]
}
However, what you could do is to never remove the TouchEvent.TOUCH_BEGIN in the Deactivate function. The touch events will never be triggered when the DisplayObject isn't on the Display List. This means you don't have to worry about adding the listener every time you want to add the button to the Display List again.
If you set the listener to use a weak reference it will not hinder the button from being garbage collected when it's not needed anymore. To make your event listener use a weak reference, set the fifth argument of the addEventListener method to true.
addEventListener(type:String, listener:Function, useCapture:Boolean = false, priority:int = 0, useWeakReference:Boolean = false):void
public function Initialize():void {
this.addEventListener(TouchEvent.TOUCH_BEGIN, OnTouchBegin, false, int.MAX_VALUE, true);
}

Answer 2

Do you call the Initialize method again at some point after closing the rollout?
From your code it looks as though you remove all of the event listeners in Deactivate and then never add the TouchEvent.TOUCH_BEGIN listener again.

Answer 3

I'm not sure what you're trying to accomplish by removing the event listeners. Since the Button has a reference to the callback, it has a reference to that callback whether the listeners are attached or not. Are you thinking that adding a listener creates a reference from the callback to the button? It doesn't--the reverse is true.
If you really want to have the Button release the callback when it is removed from the display list, then it can't hold that reference after it removes the listeners. Consider using something like Supervising Presenter or a RobotLegs Mediator to manage those dependencies.
I seriously doubt that the entire event system is being borked by what you're doing.
I'd be more inclined to believe that this:
if (listener != null)
{
_buttons[index].addEventListener(TouchEvent.TOUCH_BEGIN, listener);
}
is failing, either because the button that's referenced is not the one that's actually on stage, or because listener is null..
I have seen times where adding and removing events with priorities can cause things to fail, but typically this is with events that aren't propagating on the display list.
One way that you can test this is simply to listen to the main document or the stage for touch events and see if you're getting those events. If the entire event system is borked, you won't get them, but if your listener logic is wrong, you will.
You may also want to check the willTrigger property on the button and event.