Actionscript 3：如何在将对象作为子对象添加到另一个对象后访问该对象？

Question

我有关于缩放功能的问题。我把它作为孩子添加到另一个精灵后，我就再也无法访问我的精灵了。

以下是我的代码的相关部分（如果需要，请询问更多）

如果我尝试在我的init函数中缩放bg_image，在行spImage.addChild(bg_image);之前，没有并发症。但是我根本无法在此行之后编辑bg_image的属性（例如缩放功能）

请帮忙！

package 
{
import flash.display.MovieClip;
import flash.utils.Dictionary;
import flash.events.MouseEvent;
import flash.display.Sprite;
import flash.text.TextField;
import fl.controls.Button;
import fl.controls.List;
import flash.utils.Timer;
import flash.events.TimerEvent;
import flash.events.Event;

import flash.display.Shape;
import fl.transitions.Fly;
import fl.motion.MatrixTransformer;
import flash.events.KeyboardEvent;
import flash.geom.Matrix;
import flash.geom.Point;
import flash.ui.Mouse;

public class Main extends Sprite
{
    // Zoom

    public static var scale:Number = 1;

    public var spImage:Sprite;
    public var mat:Matrix;
    public var mcIn:MovieClip;
    public var mcOut:MovieClip;

    public var board:Sprite;
    public var boardWidth:int = 980;
    public var boardHeight:int = 661;
    public var boardMask:Shape;

    public var externalCenter:Point;
    public var internalCenter:Point;

    public const scaleFactor:Number = 0.8;
    public var minScale:Number = 0.25;
    public var maxScale:Number = 10.0;

    public var bg_image:Sprite;

            public function Main()
    {
                    addEventListener(Event.ADDED_TO_STAGE, init);
            }

    public function init(e:Event):void
    {
        removeEventListener(Event.ADDED_TO_STAGE, init);

        bg_image = new Image();

        this.graphics.beginFill(0xB6DCF4);
        this.graphics.drawRect(0,0,boardWidth,boardHeight);
        this.graphics.endFill();

        spImage = new Sprite();
        this.addChild(spImage);

        boardMask = new Shape();
        boardMask.graphics.beginFill(0xDDDDDD);
        boardMask.graphics.drawRect(0,0,boardWidth,boardHeight);
        boardMask.graphics.endFill();
        boardMask.x = 0;
        boardMask.y = 0;
        this.addChild(boardMask);
        spImage.mask = boardMask;

        minScale = boardWidth / bg_image.width;

        mcIn = new InCursorClip();
        mcOut = new OutCursorClip();

        bg_image.addChild(mcIn);
        bg_image.addChild(mcOut);

        bg_image.scaleX = minScale;
        bg_image.scaleY = minScale;

        spImage.addChild(bg_image);
        spImage.addChild(mcIn);
        spImage.addChild(mcOut);

        spImage.addEventListener(MouseEvent.MOUSE_DOWN, startDragging);
        stage.addEventListener(MouseEvent.MOUSE_UP, stopDragging);

        spImage.addEventListener(MouseEvent.CLICK, zoom);

        stage.addEventListener(KeyboardEvent.KEY_DOWN, keyHandler);
        stage.addEventListener(KeyboardEvent.KEY_UP, keyHandler);

        spImage.addEventListener(MouseEvent.MOUSE_DOWN, startDragging);
        stage.addEventListener(MouseEvent.MOUSE_UP, stopDragging);
    }

    private function startDragging(mev:MouseEvent):void
    {
        spImage.startDrag();
    }

    private function stopDragging(mev:MouseEvent):void
    {
        spImage.stopDrag();
    }

    public function zoom(mev:MouseEvent):void
    {
        if ((!mev.shiftKey)&&(!mev.ctrlKey))
        {
            return;
        }
        if ((mev.shiftKey)&&(mev.ctrlKey))
        {
            return;
        }

        externalCenter = new Point(spImage.mouseX,spImage.mouseY);
        internalCenter = new Point(bg_image.mouseX,bg_image.mouseY);

        if (mev.shiftKey)
        {
            bg_image.scaleX = Math.max(scaleFactor*bg_image.scaleX, minScale);
            bg_image.scaleY = Math.max(scaleFactor*bg_image.scaleY, minScale);

        }
        if (mev.ctrlKey)
        {
            bg_image.scaleX = Math.min(1/scaleFactor*bg_image.scaleX, maxScale);
            bg_image.scaleY = Math.min(1/scaleFactor*bg_image.scaleY, maxScale);
        }

        mat = this.transform.matrix.clone();

        MatrixTransformer.matchInternalPointWithExternal(mat,internalCenter,externalCenter);

        bg_image.transform.matrix = mat;
    }




    private function keyHandler(ke:KeyboardEvent):void
    {

        mcIn.x = spImage.mouseX;
        mcIn.y = spImage.mouseY;
        mcOut.x = spImage.mouseX;
        mcOut.y = spImage.mouseY;

        mcIn.visible = ke.ctrlKey;
        mcOut.visible = ke.shiftKey;

        if (ke.ctrlKey || ke.shiftKey)
        {
            Mouse.hide();
        }
        else
        {
            Mouse.show();
        }
    }
}

}