SingleListener

Добаляет Listener к объекту который срабатывает только 1 раз.

public class SingleListener  {
    
    public static function wrap(target: IEventDispatcher, eventName: String, callback: Function): void
    {

        var listener: Function = function (event: Event): void
        {
                try {

                    callback.call(event.currentTarget, event);
                } finally {
                    target.removeEventListener(eventName, listener);
                }

        }
        target.addEventListener(eventName, listener);
    }
    
}

Пример

[Embed(source="/res/image.png")]
[Bandable]

private var _imageSource: Class;

private var _image: Image = new Image();

override protected function createChildren(): void
{

    super.createChildren();
    addChild(_image);
    _image.source = _imageSource;
    workWithImageSize(_image.width, _image.height)

}

private function workWithImageSize(width: Number, height: Number): void
{
   trace(width + "x" + height);

}

Output:
0x0

Но на самом деле картинка "/res/image.png" имеет размеры 640x480. Т.е. реальные данные о размере картинки мы получим после первого изменения размеров объекта _image.

override protected function createChildren(): void
{
    super.createChildren();
    addChild(_image);
    _image.source = _imageSource;
    //use this strut

    SingleListener.wrap(_image, ResizeEvent.RESIZE,
       function (event: Event): void
       {

           workWithImageSize(_image.width, _image.height);
       });
}

Output:
640x480

Если после каждого изменения source требуется обработать размеры картинки, можно поступить так.

override protected function createChildren(): void
{
    super.createChildren();
    addChild(_image);
    _image.addEventListener("sourceChanged", doOnSourceChanged );
    _image.source = _imageSource;

}

private fucntion doOnSourceChanged(event: Event): void
{
    //use this strut here
    SingleListener.wrap(_image, ResizeEvent.RESIZE,
       function (event: Event): void
       {

           workWithImageSize(_image.width, _image.height);
       });
}

Custom List

List component doesn't allow to disable COPY action if Drag'n'Drop enabled. The following is a custom component that permit to disable COPY action:

package org.selectionLists
{
import mx.controls.List;
import flash.events.Event;
import mx.events.DragEvent;
import mx.managers.DragManager;

public class CustomList extends List
{

    private var _dragCopyEnabled:Boolean = false;

    public function get dragCopyEnabled():Boolean {
        return _dragCopyEnabled;
    }

    public function set dragCopyEnabled(value:Boolean):void {
        _dragCopyEnabled = value;
    }

    override protected function dragDropHandler(event:DragEvent):void {
        if (!_dragCopyEnabled) {

            event.action = DragManager.MOVE;
            DragManager.showFeedback(DragManager.MOVE);
        }

        super.dragDropHandler(event);
    }

    override protected function dragEnterHandler(event:DragEvent):void {

        if (!_dragCopyEnabled) {
            event.ctrlKey = false;
        }

        super.dragEnterHandler(event);
    }

    override protected function dragOverHandler(event:DragEvent):void {

        if (!_dragCopyEnabled) {
            event.ctrlKey = false;
        }

        super.dragOverHandler(event);
    }

}
}