Flex addEventListener - how to refresh the screen during called event?

Question

I can't seem to find the answer to what I would have thought was a common problem.
What I want to do this is:
1. Show the Open File Dialog
2. Process the file selected
3. During processing the file, report progress to the User
I have a file defined, and am using the browseForOpen and AddEventListener:
    public var fileInput:File = new File();
    fileInput.browseForOpen("Open file",[filter]);
    fileInput.addEventListener(Event.SELECT, onFileSelect);
    // Step 2 - function gets called to process the file
    private function onFileSelect(e:Event):void
        // Step 3 - do some processing, and at intervals report progress to the screen
My issue is - any changes to the screen within the event listener do not get done until the function is complete.
Any help would be appreciated,
Thanks

Answer 1

Hi Neal,
I'd suggest breaking up your processing in Step 3 so that the player has a chance to step in and update the screen. Take a look at articles on "green threads" for the basic concept:
http://blog.generalrelativity.org/?s=green
http://code.google.com/p/greenthreads/
Off the top of my head, some ways to break your processing up into chunks:
set up a Timer that fires every n milliseconds, and a listener on the Timer events that processes a chunk of the file on each event
set up an ENTER_FRAME event handler that processes a chunk of the file on each event
chain the processing of your chunks of the file with callLater() calls
Also, you may want to take a look at the ProgressBar component for reporting the progress of your processing.
HTH,
-- Tom Kraikit
Flex SDK engineer