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我刚完成一个小游戏的基本结构和保存简单的预加载到最后。傻我。AS3 - 预载实施后引用舞台
许多教程后，我发现这一个为我工作 - Pre Loader in Flash Builder
预加载的作品，游戏是在舞台上，但瞬间冻结。任何在我的LevelOne代码中对阶段的引用都会引发错误。 错误＃1009：无法访问空对象引用的属性或方法。
贯彻预载之前，我的应用程序类（RookiesGame）作为一个楼层切换。每个级别都包含在Sprite中。 RookiesGame开始加入LEVELONE至阶段，那么一旦玩家完成它，RookiesGame去除LEVELONE并添加LevelTwo至阶段等
水平的类引用阶段与_stage变量。
因为我一直都学习这种结构中，预加载器成为应用类别及RookiesGame刚刚成为另一个阶级真的搞糊涂了。不应该_stage var仍然工作？将RookiesGame作为关卡切换器可以吗？
反正主要问题是引用从水平分级阶段。
当前代码：
Preloader类
做工精细，游戏开始。
package
{
import flash.display.DisplayObject;
import flash.display.Shape;
import flash.display.Sprite;
import flash.display.StageAlign;
import flash.display.StageScaleMode;
import flash.events.Event;
import flash.utils.getDefinitionByName;
[SWF(width="650", height="450", backgroundColor="#FFFFFF", frameRate="60")]
public class Preloader extends Sprite
{
// Private
private var _preloaderBackground:Shape
private var _preloaderPercent:Shape;
private var _checkForCacheFlag:Boolean = true;
// Constants
private static const MAIN_CLASS_NAME:String = "RookiesGame";
public function Preloader()
{
trace("Preloader: Initialized.")
addEventListener(Event.ADDED_TO_STAGE, onAddedToStage);
}
public function dispose():void
{
trace("Preloader: Disposing.")
removeEventListener(Event.ENTER_FRAME, onEnterFrame);
if (_preloaderBackground)
{
removeChild(_preloaderBackground);
_preloaderBackground = null;
}
if (_preloaderPercent)
{
removeChild(_preloaderPercent);
_preloaderPercent = null;
}
}
// Private functions
private function onAddedToStage(e:Event):void
{
trace("Preloader: Added to stage.");
removeEventListener(Event.ADDED_TO_STAGE, onAddedToStage);
stage.scaleMode = StageScaleMode.SHOW_ALL;
stage.align = StageAlign.TOP_LEFT;
addEventListener(Event.ENTER_FRAME, onEnterFrame);
}
private function onEnterFrame(e:Event):void
{
if (_checkForCacheFlag == true)
{
_checkForCacheFlag = false;
if (root.loaderInfo.bytesLoaded >= root.loaderInfo.bytesTotal)
{
trace("Preloader: No need to load, all " + root.loaderInfo.bytesTotal + " bytes are cached.");
finishedLoading();
}
else
beginLoading();
}
else
{
if (root.loaderInfo.bytesLoaded >= root.loaderInfo.bytesTotal)
{
trace("Preloader: Finished loading all " + root.loaderInfo.bytesTotal + " bytes.");
finishedLoading();
}
else
{
var percent:Number = root.loaderInfo.bytesLoaded/root.loaderInfo.bytesTotal;
updateGraphic(percent);
trace("Preloader: " + (percent * 100) + " %");
}
}
}
private function beginLoading():void
{
// Might not be called if cached.
// ------------------------------
trace("Preloader: Beginning loading.")
_preloaderBackground = new Shape()
_preloaderBackground.graphics.beginFill(0x333333)
_preloaderBackground.graphics.lineStyle(2,0x000000)
_preloaderBackground.graphics.drawRect(0,0,200,20)
_preloaderBackground.graphics.endFill()
_preloaderPercent = new Shape()
_preloaderPercent.graphics.beginFill(0xFFFFFFF)
_preloaderPercent.graphics.drawRect(0,0,200,20)
_preloaderPercent.graphics.endFill()
addChild(_preloaderBackground)
addChild(_preloaderPercent)
_preloaderBackground.x = _preloaderBackground.y = 10
_preloaderPercent.x = _preloaderPercent.y = 10
_preloaderPercent.scaleX = 0
}
private function updateGraphic(percent:Number):void
{
// Might not be called if cached.
// ------------------------------
_preloaderPercent.scaleX = percent
}
private function finishedLoading():void
{
var RookiesGame:Class = getDefinitionByName(MAIN_CLASS_NAME) as Class;
if (RookiesGame == null)
throw new Error("Preloader: There is no class \"" + MAIN_CLASS_NAME + "\".");
var main:DisplayObject = new RookiesGame() as DisplayObject;
if (main == null)
throw new Error("Preloader: The class \"" + MAIN_CLASS_NAME + "\" is not a Sprite or MovieClip.");
addChild(main);
dispose();
}
}
}
RookiesGame类（以前是应用类）
的阶段的任何引用吐出来＃1009错误，当我改变stage.addChild到此 .addChild
，其停止我还没有与preloader的水平转换处理程序，所以我不知道如何stage.focus也可以！
package
{
import flash.display.MovieClip;
import flash.display.Sprite;
import flash.events.Event;
public class RookiesGame extends Sprite
{
private var _levelOne:LevelOne;
private var _levelTwo:LevelTwo;
public function RookiesGame()
{
_levelOne = new LevelOne(stage);
_levelTwo = new LevelTwo(stage);
this.addChild(_levelOne);
this.addEventListener("levelOneComplete",levelTwoSwitchHandler);
}
private function levelTwoSwitchHandler(event:Event):void
{
this.removeChild(_levelOne);
_levelOne = null;
this.addChild(_levelTwo);
stage.focus = stage;
}
}
}
LEVELONE类
地段＃1009错误。任何引用舞台的东西。
类是巨大的，所以我还是要强调的问题块。
引用阶段时，添加键盘监听器＃1009错误。
_stage.addEventListener(KeyboardEvent.KEY_DOWN, keyDownHandler);
_stage.addEventListener(KeyboardEvent.KEY_UP, keyUpHandler);
另外＃1009引用阶段时检查阶段边界。不能改变阶段。至这个。了。
private function checkStageBoundaries(gameObject:MovieClip):void
{
if (gameObject.x < 50)
{
gameObject.x = 50;
}
if (gameObject.y < 50)
{
gameObject.y = 50;
}
if (gameObject.x + gameObject.width > _stage.stageWidth - 50)
{
gameObject.x = _stage.stageWidth - gameObject.width - 50;
}
if (gameObject.y + gameObject.height > _stage.stageHeight - 50)
{
gameObject.y = _stage.stageHeight - gameObject.height - 50;
}
}
我引用_stage稍后在程序中删除事件侦听器。而已。
_stage.removeEventListener(KeyboardEvent.KEY_DOWN, keyDownHandler);
_stage.removeEventListener(KeyboardEvent.KEY_UP, keyUpHandler);
我该如何参考舞台，没有这些错误，并保持RookiesGame作为关卡切换器。
LEVELONE阶层结构
为了表明我如何使用（d）_stage。
package
{
//import classes
public class LevelOne extends Sprite
{
//Declare the variables to hold the game objects
//A variable to store the reference to the stage from the application class
private var _stage:Object;
public function LevelOne(stage:Object)
{
_stage = stage;
this.addEventListener(Event.ADDED_TO_STAGE, addedToStageHandler);
}
private function addedToStageHandler(event:Event):void
{
startGame();
this.removeEventListener(Event.ADDED_TO_STAGE, addedToStageHandler);
}
private function startGame():void
{
//Includes _stage references that mess everything up.
}
private function levelCleared():void
{
//When Level finished, dispatch event to tell RookiesGame to switch levels.
dispatchEvent(new Event("levelOneComplete", true));
}
}
}
很抱歉，如果这就是困惑，但如果你能帮助我参考一下通过LEVELONE和RookiesGame类的阶段，这将是非常赞赏。
非常感谢。你完全去除_stage变量也是正确的。我一直在学习的文本使用_stage var和ADDED_TO_STAGE？奇怪。再次感谢！ – Rookie