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我剛完成一個小遊戲的基本結構和保存簡單的預加載到最後。傻我。AS3 - 預載實施後引用舞臺
許多教程後，我發現這一個爲我工作 - Pre Loader in Flash Builder
預加載的作品，遊戲是在舞臺上，但瞬間凍結。任何在我的LevelOne代碼中對階段的引用都會引發錯誤。 錯誤＃1009：無法訪問空對象引用的屬性或方法。
貫徹預載之前，我的應用程序類（RookiesGame）作爲一個樓層切換。每個級別都包含在Sprite中。 RookiesGame開始加入LEVELONE至階段，那麼一旦玩家完成它，RookiesGame去除LEVELONE並添加LevelTwo至階段等
水平的類引用階段與_stage變量。
因爲我一直都學習這種結構中，預加載器成爲應用類別及RookiesGame剛剛成爲另一個階級真的搞糊塗了。不應該_stage var仍然工作？將RookiesGame作爲關卡切換器可以嗎？
反正主要問題是引用從水平分級階段。
當前代碼：
Preloader類
做工精細，遊戲開始。
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類（以前是應用類）
的階段的任何引用吐出來＃1009錯誤，當我改變stage.addChild到此 .addChild
，其停止我還沒有與preloader的水平轉換處理程序，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類
地段＃1009錯誤。任何引用舞臺的東西。
類是巨大的，所以我還是要強調的問題塊。
引用階段時，添加鍵盤監聽器＃1009錯誤。
_stage.addEventListener(KeyboardEvent.KEY_DOWN, keyDownHandler);
_stage.addEventListener(KeyboardEvent.KEY_UP, keyUpHandler);
另外＃1009引用階段時檢查階段邊界。不能改變階段。至這個。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稍後在程序中刪除事件偵聽器。而已。
_stage.removeEventListener(KeyboardEvent.KEY_DOWN, keyDownHandler);
_stage.removeEventListener(KeyboardEvent.KEY_UP, keyUpHandler);
我該如何參考舞臺，沒有這些錯誤，並保持RookiesGame作爲關卡切換器。
LEVELONE階層結構
爲了表明我如何使用（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，如果這就是困惑，但如果你能幫助我參考一下通過LEVELONE和RookiesGame類的階段，這將是非常讚賞。
非常感謝。你完全去除_stage變量也是正確的。我一直在學習的文本使用_stage var和ADDED_TO_STAGE？奇怪。再次感謝！ – Rookie