flex修改application加载进度条preloader的位置
flex修改application加载进度条preloader的位置 博客分类： flex
FlexAdobeFlash.哎查点资料还要科学上网。。。




如果flex页面的高度超过屏幕默认高度的话，有可能application初始化进度条看不到，




因为preloader的位置始终是居中的，虽然它事实上是存在的，但是很可能需要将滚动条下拉




才能看见，不知情的可能以为页面假死了。下面就介绍如何修改preloader的位置。




来源：http://www.mehtanirav.com/2010/03/19/showing-flex-preloader-near-the-top-of-your-application







自定义进度条：
Java代码
1.package com.components
2.{
3. import flash.events.ProgressEvent;
4. import mx.preloaders.DownloadProgressBar;
5.
6. public class MyDownloadProgressBar extends DownloadProgressBar
7. {
8. public function MyDownloadProgressBar()
9. {
10. super();
11. // Set the download label.
12. downloadingLabel="Downloading..."
13. // Set the initialization label.
14. initializingLabel="Initializing..."
15. }
16.
17. // Override to return true so progress bar appears during initialization.
18. override protected function showDisplayForInit(elapsedTime:int, count:int):Boolean {
19. return true;
20. }
21.
22. // Override to return true so progress bar appears during download.
23. override protected function showDisplayForDownloading(elapsedTime:int, event:ProgressEvent):Boolean {
24. return true;
25. }
26.
27. // Override initialize so that we can position the loader
28. override public function initialize():void {
29. super.initialize();
30. center(stageWidth, (stageHeight > 250) ? 250 : stageHeight);
31. }
32. }
33.}
package com.components
{
import flash.events.ProgressEvent;
import mx.preloaders.DownloadProgressBar;

public class MyDownloadProgressBar extends DownloadProgressBar
{
public function MyDownloadProgressBar()
{
super();
// Set the download label.
downloadingLabel="Downloading..."
// Set the initialization label.
initializingLabel="Initializing..."
}

// Override to return true so progress bar appears during initialization.
override protected function showDisplayForInit(elapsedTime:int, count:int):Boolean {
return true;
}

// Override to return true so progress bar appears during download.
override protected function showDisplayForDownloading(elapsedTime:int, event:ProgressEvent):Boolean {
return true;
}

// Override initialize so that we can position the loader
override public function initialize():void {
super.initialize();
center(stageWidth, (stageHeight > 250) ? 250 : stageHeight);
}
}
}







在Application页面这样写：





Java代码
1.<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
2. preloader="com.components.MyDownloadProgressBar">
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
preloader="com.components.MyDownloadProgressBar">






或者在Flex4里





Java代码
1.<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
2. xmlns:s="library://ns.adobe.com/flex/spark"
3. xmlns:mx="library://ns.adobe.com/flex/mx"
4. xmlns:components="components.*"
5. preloader="components.MyDownloadProgressBar" >
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark"
xmlns:mx="library://ns.adobe.com/flex/mx"
xmlns:components="components.*"
preloader="components.MyDownloadProgressBar" >



其中关键代码是initialize函数里的



center(stageWidth, (stageHeight > 250) ? 250 : stageHeight)，这句的意思是如果屏幕高度超过