DrawingTool - Eliminar ultimo lineTo

/**
 * Code by rodrigolopezpeker (aka 7interactive™) on 4/7/14 12:16 PM.
 */
package labs {
import flash.display.GraphicsPath;
import flash.display.IGraphicsData;
import flash.display.Shape;
import flash.display.Sprite;
import flash.display.StageAlign;
import flash.display.StageScaleMode;
import flash.events.Event;
import flash.events.KeyboardEvent;
import flash.events.MouseEvent;
import flash.ui.Keyboard;

[SWF(width="800", height="600", backgroundColor="#323232", frameRate="60")]
public class TestDrawing extends Sprite {

    private var _shape:Shape;
    private var isPressing:Boolean;

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

    private function init(event:Event):void {
        removeEventListener(Event.ADDED_TO_STAGE, init);
        stage.scaleMode = StageScaleMode.NO_SCALE;
        stage.align = StageAlign.TOP_LEFT;
        stage.showDefaultContextMenu = false;
        _shape = new Shape();
        addChild(_shape);
        stage.addEventListener(MouseEvent.MOUSE_DOWN, handleMousePress);
        stage.addEventListener(KeyboardEvent.KEY_DOWN, handleKey);
    }

    private function handleKey(event:KeyboardEvent):void {
        if (isPressing) return;
        if (event.keyCode == Keyboard.BACKSPACE) {
            removeLastLineTo();
        }
    }

    private function removeLastLineTo():void {
        var gd:Vector.<IGraphicsData> = _shape.graphics.readGraphicsData(false);
        var len:int = gd.length;
        var lastPath:GraphicsPath;
        for (var i:int = len - 1; i >= 0; i--) {
            if (gd[i] is GraphicsPath) {
                lastPath = gd[i] as GraphicsPath;
                break;
            }
        }
        if (!lastPath) return;
        var lastLineToIndex:int = lastPath.commands.lastIndexOf(2);
        if (lastLineToIndex > -1) {
            lastPath.commands.splice(lastLineToIndex, 1);
            lastPath.data.splice(lastPath.data.length - 2, 2);
            // actualiza graphicData.
            _shape.graphics.clear();
            _shape.graphics.drawGraphicsData(gd);
        }
    }

    private function handleMousePress(event:MouseEvent):void {
        isPressing = true;
        stage.addEventListener(MouseEvent.MOUSE_UP, handleMouseRelease);
        stage.addEventListener(MouseEvent.MOUSE_MOVE, handleMouseMove);
        _shape.graphics.lineStyle(0, 0xff0000);
        _shape.graphics.moveTo(mouseX, mouseY);
    }

    private function handleMouseMove(event:MouseEvent):void {
        _shape.graphics.lineTo(mouseX, mouseY);
        event.updateAfterEvent();
    }

    private function handleMouseRelease(event:MouseEvent):void {
        isPressing = false;
        stage.removeEventListener(MouseEvent.MOUSE_UP, handleMouseRelease);
        stage.removeEventListener(MouseEvent.MOUSE_MOVE, handleMouseMove);
    }
}
}