Flex中进度条的使用

使用方法：
设置Application标签的preloader为 MyComponent.MyDownloadProgressBar
<mx:Application preloader="MyComponent.MyDownloadProgressBar" >

下面是 MyDownloadProgressBar.as的代码：

package MyComponent
{
import flash.display.*;
import flash.events.*;
import flash.filters.BitmapFilterQuality;
import flash.filters.BlurFilter;
import flash.geom.Matrix;
import flash.net.*;
import flash.text.TextField;
import flash.utils.*;
import flash.system.Capabilities;

import mx.events.*;
import mx.preloaders.*;

public class MyDownloadProgressBar extends Sprite implements IPreloaderDisplay
{       
[Embed(source="logo.png", mimeType="application/octet-stream")]
public var _loadingLogo:Class;

private var dpbImageControl:Loader;
private var _barSprite:Sprite;
private var progressText:TextField;       
private var ProgressBarSpritIsAdded:Boolean = false;

public function MyDownloadProgressBar() {  
super();                           
}

// Specify the event listeners.
public function set preloader(preloader:Sprite):void {
//Listen for 正在下载
preloader.addEventListener(ProgressEvent.PROGRESS, handleProgress);
//Listen for 下载完成
preloader.addEventListener(Event.COMPLETE, handleComplete);
//Listen for 正在初始化
preloader.addEventListener(FlexEvent.INIT_PROGRESS, handleInitProgress);
//Listen for 初始化完成
preloader.addEventListener(FlexEvent.INIT_COMPLETE, handleInitComplete);
}

// Initialize the Loader control in the override
// of IPreloaderDisplay.initialize().
public function initialize():void {
//添加logo图
dpbImageControl = new Loader();      
dpbImageControl.contentLoaderInfo.addEventListener(Event.COMPLETE, loader_completeHandler);
dpbImageControl.loadBytes(new _loadingLogo() as ByteArray);
//dpbImageControl.load(new URLRequest("loadinglogo.swf"));
}


// After the SWF file loads, set the size of the Loader control.
private function loader_completeHandler(event:Event):void
{        
addChild(dpbImageControl);
dpbImageControl.width = 230;
dpbImageControl.height= 80;
dpbImageControl.x = this.stage.stageWidth/2 - dpbImageControl.width/2;
dpbImageControl.y = this.stage.stageHeight/2 - dpbImageControl.height/2 - 80;
}  

//
private function addProgressBarSprit():void{
//绘制背景渐变
var matrix:Matrix=new Matrix();
matrix.createGradientBox(this.stage.stageWidth,this.stage.stageHeight,Math.PI/2);
var colors:Array=[0x058BBD,0xFFFFFF];
var alphas:Array=[1,1];
var ratios:Array=[0,255];
this.graphics.lineStyle();
this.graphics.beginGradientFill(GradientType.LINEAR,colors,alphas,ratios,matrix);       
this.graphics.drawRect(0,0,this.stage.stageWidth,this.stage.stageHeight);
this.graphics.endFill();

//绘制中心白色发光
var _Sprite1:Sprite = new Sprite();
addChild(_Sprite1);
_Sprite1.graphics.beginFill(0xffffff,0.45);
_Sprite1.graphics.drawEllipse(this.stage.stageWidth/2-130, this.stage.stageHeight/2-90, 280, 100);
_Sprite1.graphics.endFill();
//滤镜实现发光边缘柔和           
var blur:BlurFilter = new BlurFilter();
blur.blurX = 100;
blur.blurY = 50;
blur.quality = BitmapFilterQuality.HIGH;
_Sprite1.filters = [blur];

//-------------------------------------------------

//绘制进度条背景
var _Sprite2:Sprite = new Sprite();
addChild(_Sprite2);
_Sprite2.graphics.lineStyle(1, 0xCCCCCC);
_Sprite2.graphics.beginFill(0xFFFFFF);
_Sprite2.graphics.drawRect((this.stage.stageWidth/2 - 152), (this.stage.stageHeight/2 - 10), 304, 20);  
_Sprite2.graphics.endFill();

//-------------------------------------------------

//加 载进度条Sprite
_barSprite = new Sprite();
addChild(_barSprite);
_barSprite.x = this.stage.stageWidth/2 - 150;
_barSprite.y = this.stage.stageHeight/2 - 8;

//-------------------------------------------------

//加载进度条文字
progressText = new TextField();
addChild(progressText);
progressText.textColor = 0x333333;
progressText.width = 300;
progressText.height = 18;
progressText.x = this.stage.stageWidth/2 - 152;
progressText.y = this.stage.stageHeight/2 + 20;
}

//刷新进度条
private function drawProgressBar(bytesLoaded:Number, bytesTotal:Number):void
{  
if (_barSprite != null && progressText != null){
var g:Graphics = _barSprite.graphics;
g.clear();
//    g.beginFill(0xCCCCCC);
//    g.drawRect(0, 0, 300*(bytesLoaded/bytesTotal),16);  
//    g.endFill();   

var matrix:Matrix=new Matrix();
matrix.createGradientBox(300*(bytesLoaded/bytesTotal),16,Math.PI/2);
var colors:Array=[0x0099CC,0x99cc77];
var alphas:Array=[1,1];
var ratios:Array=[0,255];
g.lineStyle();
g.beginGradientFill(GradientType.LINEAR,colors,alphas,ratios,matrix);       
g.drawRect(0,0,300*(bytesLoaded/bytesTotal),16);
g.endFill(); 


}
}

//正在下载的进度
private function handleProgress(event:ProgressEvent):void {
//第一次处理时绘制进度条Sprit
if (ProgressBarSpritIsAdded == false){
ProgressBarSpritIsAdded = true;
addProgressBarSprit();
}

if (progressText != null){
progressText.text = "下载进度：已下载 " + event.bytesLoaded + " byte，总大小 " + event.bytesTotal + " byte.";
}        
drawProgressBar(event.bytesLoaded, event.bytesTotal);
}

private function handleComplete(event:Event):void {
if (progressText != null){
progressText.text = "下载完成.";
}
drawProgressBar(1,1);       
}

private function handleInitProgress(event:Event):void {
if (progressText != null){
progressText.text = "正在初始化...";
}
drawProgressBar(1,1);
}

private function handleInitComplete(event:Event):void {
if (progressText != null){
progressText.text = "初始化完成.";
}
drawProgressBar(1,1);        

//0.03秒后抛出完成事件
var timer:Timer = new Timer(300,1);
timer.addEventListener(TimerEvent.TIMER, dispatchComplete);
timer.start();     
}

private function dispatchComplete(event:TimerEvent):void {
dispatchEvent(new Event(Event.COMPLETE));
}


// Implement IPreloaderDisplay interface

public function get backgroundColor():uint {
return 0;
}

public function set backgroundColor(value:uint):void {
}

public function get backgroundAlpha():Number {
return 0;
}

public function set backgroundAlpha(value:Number):void {
}

public function get backgroundImage():Object {
return undefined;
}

public function set backgroundImage(value:Object):void {
}

public function get backgroundSize():String {
return "";
}

public function set backgroundSize(value:String):void {
}

public function get stageWidth():Number {
return 500;
}

public function set stageWidth(value:Number):void {
}

public function get stageHeight():Number {
return 375;
}

public function set stageHeight(value:Number):void {
}
}

}