flex默认的preloader已经很不错了,可是有时候还是需要自定义的.

 

需要在要出现自定义预加载的程序的<mx:Application>标签里加入preloader="".

preloader="com.lichen.component.CustomPreloader"

其中,com.lichen.component是我的包名,CustomPreloader这个类是继承了DownloadProgressBar

这句就是指明了程序preloader的时候加载哪个类

 

CustomPreloader.as

package com.lichen.component

{

  

import flash.display.Sprite;

  

import flash.events.Event;

  

import flash.events.ProgressEvent;

  

import flash.text.TextField;

    

  

import flashx.textLayout.BuildInfo;

    

  

import mx.events.*;

  

import mx.preloaders.DownloadProgressBar;

    

  

public

class CustomPreloader

extends DownloadProgressBar {

    

    

public var wcs:WelcomeScreen;

    

public var msg:TextField;

    

public function CustomPreloader()    

    {

      

super();    

      msg=

new TextField();

      wcs =

new WelcomeScreen();

        

      

this.addChild(wcs);

      

this.addChild(msg);

    }

    

    override

public function set preloader( preloader:Sprite ):

void    

    {                                        

      preloader.addEventListener( ProgressEvent.PROGRESS , SWFDownloadProgress );        

      preloader.addEventListener( Event.COMPLETE , SWFDownloadComplete );

      preloader.addEventListener( FlexEvent.INIT_PROGRESS , FlexInitProgress );

      preloader.addEventListener( FlexEvent.INIT_COMPLETE , FlexInitComplete );

    }

    

    

private function SWFDownloadProgress( event:ProgressEvent ):

void {

      msg.text=String(

int(event.bytesLoaded/event.bytesTotal*100))+

" %";

      msg.background=

true;

      msg.backgroundColor=0xD4E4FF;

      msg.width=200;

      msg.height=20;

      msg.textColor=0x444444;

    }

    

    

private function SWFDownloadComplete( event:Event ):

void {}

    

    

private function FlexInitProgress( event:Event ):

void {

//      wcs.ready = true;

      msg.text=

"完成了!";

      wcs.closeScreen();

      dispatchEvent(

new Event(Event.COMPLETE));

    }

    

    

private function FlexInitComplete( event:Event ):

void    

    {            

//      wcs.ready = true;            

//      dispatchEvent( new Event( Event.COMPLETE ) );

    }

    

  }

}

 

这其中使用了WelcomeScreen,这个类的作用是使用图片,并且设置定时器控制图片显示的alpha属性.

WelcomeScreen.as

package com.lichen.component    

{        

  

import flash.display.Loader;

  

import flash.events.MouseEvent;

  

import flash.events.TimerEvent;

  

import flash.utils.ByteArray;

  

import flash.utils.Timer;

    

  

public

class WelcomeScreen

extends Loader

  {

    [ Embed(source=

"images/mt.jpg", mimeType=

"application/octet-stream") ]

    

public var WelcomeScreenGraphic:Class;

    

public var timer:Timer;

    

private var fadeInRate:Number    = .05;

    

private var fadeOutRate:Number = .08;

    

private var timeAutoClose:

int = 500;

    

public var ready:Boolean =

false;    

    

    

public function WelcomeScreen()

    {

      

this.visible =

false;

      

this.alpha = 0.5;

      timer =

new Timer( 1 );

      timer.addEventListener( TimerEvent.TIMER, updateView );

      timer.start();

      

this.loadBytes(

new WelcomeScreenGraphic() as ByteArray );

      

this.addEventListener( MouseEvent.MOUSE_DOWN, mouseDown );                            

    }

    

    

public function updateView( event:TimerEvent ):

void

    {

      

if(

this.alpha < 1)        

this.alpha =

this.alpha +

this.fadeInRate;

      

if(

this.stage.stageWidth>0){

        

this.stage.addChild(

this);

        

this.x =

this.stage.stageWidth/2 -

this.width/2;

        

this.y =

this.stage.stageHeight/2 -

this.height/2;

        

this.visible=

true;

      }

      

if(

this.ready && timer.currentCount >

this.timeAutoClose ) closeScreen()        

    }

    

    

public function closeScreen():

void

    {

      timer.removeEventListener( TimerEvent.TIMER, updateView );

      timer.removeEventListener( MouseEvent.MOUSE_DOWN, mouseDown);

      timer.addEventListener( TimerEvent.TIMER, closeScreenFade );                                        

    }

    

    

public function closeScreenFade( event:TimerEvent ):

void

    {

      

if(

this.alpha > 0){

        

this.alpha =

this.alpha - fadeOutRate;

      }

else {

        timer.stop()

        

this.parent.removeChild(

this);

      }                

    }                

    

    

public function mouseDown( event:MouseEvent ):

void

    {

      closeScreen();                

    }

  }

}    

 

最终的效果图