flex: how to know preloader progress?

I know that preloader is the first piece downloaded and it will load the large part of the swf. I want to know the progress of the large part downloading, and for simplicity I don't need UI to display the开发者_如何转开发 percentage, the data will be passed to HTML, HTML will handle the UI.

Is there any easy way to get the preloader event in flex? Without adding a lot of code in flex?

Thanks.

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You extend the download progress bar class and use it instead of the default. You can get the progress of the download then. Good example here