Flex 4中的自定義預加載器？

Question

是否有人在Flex 4中成功實現了自定義預加載器？根據我的經驗，當我在應用程序標記中使用preloader =「com.foo.MyPreloader」指定自定義預加載器時，預加載器在SWF完全下載之前不會顯示，從而破壞了預加載器的用途！也許這是靜止測試Flex 4框架中的一個錯誤？

Answer 1

我覺得很愚蠢......我在preloader中引用了我的一個主要應用程序類，因此導致我的所有類都被編譯到preloader中，這意味着它不能顯示preloader，直到所有內容加載完畢。

以供將來參考：仔細檢查您的預加載每個引用，請確保您使用什麼比絕對必要的更多

Answer 2

有一個Flex 4自定義預加載代碼在這裏樣品http://www.leavethatthingalone.com/blog/index.cfm/2009/11/11/Flex4CustomPreloader

Answer 3

我已經在許多Flex3項目中一直使用這個例子。它仍然可以使用Flex4 sdk：

我可以記住我從哪裏得到它。而你，當你說，重要的是這個腳本不引用任何事情的權利...

<s:Application tag ... preloader="com.YYY.XXX.shell.view.CustomPreloader" 

CustomPreloader

package com.YYY.XXX.shell.view 
{ 
    import flash.display.Sprite; 
    import flash.events.Event; 
    import flash.events.ProgressEvent; 
    import flash.events.TimerEvent; 
    import flash.utils.Timer; 

    import mx.events.FlexEvent; 
    import mx.preloaders.DownloadProgressBar; 

    public final class CustomPreloader 
     extends DownloadProgressBar 
    { 
     public var loader : LoadScreen; 
     private var _timer : Timer; 

     public function CustomPreloader() 
     { 
      super(); 
     } 

     override public function initialize() : void 
     { 
      super.initialize(); 

      this.loader = new LoadScreen(); 
      this.addChild(this.loader); 

      this._timer = new Timer(1); 
      this._timer.addEventListener(TimerEvent.TIMER, handleTimerTick); 
      this._timer.start(); 
     } 

     override public function set preloader(preloader : Sprite):void 
     {     
      preloader.addEventListener(ProgressEvent.PROGRESS, SWFDownLoadScreen); 
      preloader.addEventListener(Event.COMPLETE,   SWFDownloadComplete); 
      preloader.addEventListener(FlexEvent.INIT_PROGRESS, FlexInitProgress); 
      preloader.addEventListener(FlexEvent.INIT_COMPLETE, FlexInitComplete); 
     } 

     private function SWFDownLoadScreen(event : ProgressEvent) : void 
     { 
      var prog : Number = event.bytesLoaded/event.bytesTotal * 100; 
      if (this.loader) 
      { 
       this.loader.progress = prog; 
      } 
     } 

     private function handleTimerTick(event : TimerEvent) : void 
     { 
      this.stage.addChild(this); 
      this.loader.x = (this.stageWidth - this.loader.width)/2; 
      this.loader.y = (this.stageHeight - this.loader.height)/2; 
      this.loader.refresh(); 
     } 

     private function SWFDownloadComplete(event : Event) : void {} 

     private function FlexInitProgress(event : Event) : void {} 

     private function FlexInitComplete(event : Event) : void 
     {  
      this.loader.ready = true; 
      this._timer.stop(); 
      this.dispatchEvent(new Event(Event.COMPLETE)); 
     } 

     override protected function showDisplayForInit(elapsedTime:int, count:int):Boolean 
     { 
      return true; 
     } 

     override protected function showDisplayForDownloading(elapsedTime:int, 
                event:ProgressEvent):Boolean 
     { 
      return true; 
     } 
    } 
} 

LoadScreen

package com.YYY.XXX.shell.view 
{ 

    import flash.display.Bitmap; 
    import flash.display.BitmapData; 
    import flash.display.Graphics; 
    import flash.display.Loader; 
    import flash.display.Sprite; 
    import flash.utils.ByteArray; 

    import mx.graphics.codec.PNGEncoder; 

    public class LoadScreen extends Loader { 

     //~ Settings ---------------------------------------------------------- 
     private static var _BarWidth  : int = 153; // Progress bar width 
     private static var _BarHeight : int = 12; // Progress bar height 
     private static var _LogoHeight : int = 153; // Logo picture height 
     private static var _LogoWidth : int = 68; // Logo picture width 
     private static var _Padding  : int = 5; // Spacing between logo and progress bar 
     private static var _LeftMargin : int = 0; // Left Margin 
     private static var _RightMargin : int = 0; // Right Margin 
     private static var _TopMargin : int = 1; // Top Margin 
     private static var _BottomMargin : int = 1; // Bottom Margin 

     private static var _BarBackground : uint = 0xFFFFFF; // background of progress bar 
     private static var _BarOuterBorder : uint = 0x737373; // color of outer border 
     private static var _BarColor  : uint = 0x6F9FD5; // color of prog bar 
     private static var _BarInnerColor : uint = 0xFFFFFF; // inner color of prog bar 

     //~ Instance Attributes ----------------------------------------------- 
     [Embed(source="/asset/embed/img/XXX.gif")] 
     private var MyLogoClass: Class; 
     private var _logo : Bitmap; 
     private var _logoData : BitmapData; 

     private var isReady : Boolean = false; 
     public var progress : Number; 

     //~ Constructor -------------------------------------------------------   
     public function LoadScreen() 
     { 
      super(); 
      this.progress = 0; 
      this._logo = new MyLogoClass as Bitmap; 
     } 

     //~ Methods ----------------------------------------------------------- 
     public function refresh() : void 
     { 
      this._logoData = this.draw(); 
      var encoder : PNGEncoder = new PNGEncoder(); 
      var bytes : ByteArray = encoder.encode(this._logoData); 
      this.loadBytes(bytes); 
     } 

     override public function get width() : Number 
     { 
      return Math.max(_BarWidth, _LogoWidth) + _LeftMargin + _RightMargin; 
     } 

     override public function get height() : Number 
     { 
      return _LogoHeight + _BarHeight + _Padding + _TopMargin + _BottomMargin; 
     } 

     private function draw() : BitmapData 
     { 
      // create bitmap data to create the data 
      var data : BitmapData = new BitmapData(this.width, this.height, true, 0); 

      // draw the progress bar 
      var s : Sprite = new Sprite(); 
      var g : Graphics = s.graphics; 

      // draw the bar background 
      g.beginFill(_BarBackground); 
      g.lineStyle(2, _BarOuterBorder, 1, true); 
      var px : int = (this.width - _BarWidth)/2; 
      var py : int = _TopMargin + _LogoHeight + _Padding; 
      g.drawRoundRect(px, py, _BarWidth, _BarHeight, 2); 
      var containerWidth : Number = _BarWidth - 4; 
      var progWidth : Number = containerWidth * this.progress/100; 
      g.beginFill(_BarColor); 
      g.lineStyle(1, _BarInnerColor, 1, true); 
      g.drawRect(px + 1, py + 1, progWidth, _BarHeight - 3); 
      data.draw(s); 

      // draw the logo 
      data.draw(this._logo.bitmapData, null, null, null, null, true); 
      return data; 
     } 

     public function set ready(value : Boolean) : void 
     { 
      this.isReady = value; 
      this.visible = !this.isReady; 
     } 

     public function get ready() : Boolean { return this.isReady; } 

    } 
}