Flex移动端主程序属性 splashScreenImage : 可以设置预加载图片。
可是他只支持MXML，不支持ActionScript编写
提供解决方案处理此问题。
环境 ：Flex 4.6.0 （必须，如果为4.5的话，当旋转屏幕时会报错）
1：ImagePreloader预加载类
package { import flash.display.Bitmap; import flash.display.DisplayObject; import flash.display.Loader; import flash.display.Sprite; import flash.events.Event; import flash.events.IOErrorEvent; import flash.geom.Matrix; import flash.net.URLRequest; import flash.utils.getTimer; import mx.events.FlexEvent; import mx.preloaders.IPreloaderDisplay; import mx.preloaders.Preloader; /** *<p> Image Preloader</p> * replace the property splashScreenImage of Application, * it can be dynamic changed by splashImageUrl and suppport ActionScript * @author yaoyf * @date 2012-07-02 * */ public class ImagePreloader extends Sprite implements IPreloaderDisplay { private const LETTERBOX:String = "letterbox"; private const ZOOM:String = "zoom"; private const STRETCH:String = "stretch"; private var splashImage:DisplayObject; private var splashImageWidth:Number; private var splashImageHeight:Number; private var SplashImageClass:Class = null; private var loader:Loader = null; private var scaleMode:String = LETTERBOX; private var minimumDisplayTime:Number = 3000; private var checkWaitTime:Boolean = false; private var displayTimeStart:int = -1; private var _stageHeight:Number; private var _stageWidth:Number; private var splashImageUrl:String = null; public function ImagePreloader() { super(); } /** * initialize * */ public function initialize():void { splashImageUrl = "preloader.jpg";//your image url checkWaitTime = minimumDisplayTime > 0; if (checkWaitTime) if(displayTimeStart == -1) this.displayTimeStart = flash.utils.getTimer(); loader = new Loader(); loader.load(new URLRequest(splashImageUrl)); loader.contentLoaderInfo.addEventListener(Event.COMPLETE,onComplete); loader.contentLoaderInfo.addEventListener(IOErrorEvent.IO_ERROR,onIoEvent); this.stage.addEventListener(Event.RESIZE, stageResizeHandler, false , 0, true ); } private function stageResizeHandler(event:Event):void { scaleMatrix(); } protected function onIoEvent(event:IOErrorEvent):void{trace("IOError has occured : " + event.text);} protected function onComplete(event:Event):void { dispose(); splashImage = Bitmap(event.target.content); addChildAt(splashImage, 0); this.splashImageWidth = splashImage.width; this.splashImageHeight = splashImage.height; scaleMatrix(); } /** * scale matrix of splashImage * */ private function scaleMatrix():void { if (!splashImage) return; var dpiScale:Number = this.root.scaleX; var stageWidth:Number = stage.stageWidth / dpiScale; var stageHeight:Number = stage.stageHeight / dpiScale; var Number = splashImageWidth; var height:Number = splashImageHeight; var m:Matrix = new Matrix(); var scaleX:Number = 1; var scaleY:Number = 1; switch(scaleMode) { case ZOOM: scaleX = Math.max( stageWidth / width, stageHeight / height); scaleY = scaleX; break; case LETTERBOX: scaleX = Math.min( stageWidth / width, stageHeight / height); scaleY = scaleX; break; case STRETCH: scaleX = stageWidth / width; scaleY = stageHeight / height; break; } if (scaleX != 1 || scaleY != 0) { width *= scaleX; height *= scaleY; m.scale(scaleX, scaleY); } m.translate(-width / 2, -height / 2); m.translate(stageWidth / 2, stageHeight / 2); splashImage.transform.matrix = m; } /** * get current display time * */ private function get currentDisplayTime():int { if (-1 == displayTimeStart) return -1; return flash.utils.getTimer() - displayTimeStart; } //implements public function set preloader(obj:Sprite):void { obj.addEventListener(FlexEvent.INIT_COMPLETE, preloader_initCompleteHandler, false, 0, true); } private function preloader_initCompleteHandler(event:Event):void { if (checkWaitTime && currentDisplayTime < minimumDisplayTime) this.addEventListener(Event.ENTER_FRAME, initCompleteEnterFrameHandler); else dispatchComplete(); } private function initCompleteEnterFrameHandler(event:Event):void { if (currentDisplayTime <= minimumDisplayTime)return; dispatchComplete(); } private function dispatchComplete():void { dispose(); var preloader:Preloader = this.parent as Preloader; preloader.removeEventListener(FlexEvent.INIT_COMPLETE, preloader_initCompleteHandler, false); this.removeEventListener(Event.ENTER_FRAME, initCompleteEnterFrameHandler); this.stage.removeEventListener(Event.RESIZE, stageResizeHandler, false); dispatchEvent(new Event(Event.COMPLETE)); } /** * dispose resource * */ private function dispose():void { if(splashImage) { if(this.contains(splashImage)) this.removeChild(splashImage); var bit:Bitmap = splashImage as Bitmap; if(bit.bitmapData) { bit.bitmapData.dispose(); bit.bitmapData = null; } } } //----------------implements-----------------// public function get backgroundAlpha():Number{return 0;} public function set backgroundAlpha(value:Number):void{} public function get backgroundColor():uint{return 0;} public function set backgroundColor(value:uint):void{} public function get backgroundImage():Object{return null;} public function set backgroundImage(value:Object):void{} public function get backgroundSize():String{return null;} public function set backgroundSize(value:String):void{} public function get stageHeight():Number{return _stageHeight;} public function set stageHeight(value:Number):void{_stageHeight = value;} public function get stageWidth():Number{return _stageWidth;} public function set stageWidth(value:Number):void{_stageWidth = value;} } }
2：调用方式：
主程序中
<?xml version="1.0" encoding="utf-8"?> <s:ViewNavigatorApplication xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark" firstView="views.Sample_FlexMobilePreloaderView" applicationDPI="160" preloader="ImagePreloader"> </s:ViewNavigatorApplication>