how to detect children size change actionscript? - actionscript-3

Question

if i got a container,there were children display object in it.
the container's size was decided by the children's size.when the size change i need to do something to fit the new size.
since i didn't find the kind of event to detect it,i use ENTER_FRAME event,that's quite silly.
keep every last frame's size,and compare to current frame.maybe the size changed after you deal with the enter frame event,so in some cases,you might see the correct result in the next frame.
i don't think it's a good solution for a component.give me you ideas,thanks.

Answer 1

Well there is no standard solution for this. You could create a custom class which overrides the setters of width/height/x/y/scaleX/scaleY/scrollRect .. and maybe some other properties. The children should extend such a class.
I used a boolean to prevent its dispatched multiple times, after a frame the flag will be resetted.
override public function set width(value:Number):void
{
if (value !== super.width && !isNaN(Number(value)) this.dispatchResize();
super.width = value;
}
override public function set height(value:Number):void
{
if (value !== super.height && !isNaN(Number(value)) this.dispatchResize();
super.height = value;
}
override public function set scaleX(value:Number):void
{
if (value !== super.scaleX && !isNaN(Number(value)) this.dispatchResize();
super.scaleX = value;
}
override public function set scaleY(value:Number):void
{
if (value !== super.scaleY && !isNaN(Number(value)) this.dispatchResize();
super.scaleY = value;
}
private var _hasDispatchedResize:Boolean;
protected function dispatchResize():void
{
// do something
if (!this._hasDispatchedResize)
{
this.dispatchEvent(new Event(Event.RESIZE));
this._hasDispatchedResize = true;
this.addEventListener(Event.ENTER_FRAME, handleEnterFrameOnce);
}
}
private function handleEnterFrameOnce(event:Event):void
{
this.removeEventListener(Event.ENTER_FRAME, handleEnterFrameOnce);
this._hasDispatchedResize = false;
}
Now, in the container class you can listen to a Event.RESIZE of the children. Your not really sure if the value actually changed (in case of a frame change on a MovieClip), but in most cases this will work. I've added an extra check inside this setters before dispatching the resize. It depends on the case if this will suit your case.

Answer 2

What I would do is whatever function resizes the children, add your own dispatch event to it that would broadcast that a size change occurred.
//Never forget to import your classes.
import flash.events.EventDispatcher;
import flash.events.Event;
//Our custom listener listens for our custom event, then calls the function we
//want called when children are resized.
addEventListener("childResized", honeyIResizedTheChildren);
function resizingLikeFun(){
datClip.width++;//they be resizin, yo.
dispatchEvent(new Event("childResized"));//Our custom event
}
function honeyIResizedTheChildren(e:Event){
trace("Giant Cheerios");
//Whatever you want to do when the children are resized goes here.
}
I assume some things with that code, so let me know if this doesn't fully apply to you.