Spark BusyIndicator not working - apache-flex

Question

I have a busy function taking several of seconds to be executed. At the top of the function I set my busy indicator to be visible and at the bottom I set it to be invisible. But the display does not change while the function is executed and the busy indicator does not appear. here is the code structure
public function busyFunction():void{
busyIndicator.visible = true;
doStuff .. // takes several seconds
busyIndicator.visible = false;
}
i just want the first line (busyIndicator.visible = true) to be executed while the doStuff is on progress.
Regards

Answer 1

The problem is because Flex doesn't redraw the screen while your method is executing. So you make the busy indicator visible, do stuff, and hide the indicator. But no update to the screen will have occurred yet, so the indicator never shows.
The Flex "elastic racetrack" paradigm basically says that your app consists of two cycles, one where your logic is executed, and another where the screen is updated. So you need to set the busy indicator to visible, and then make it go away after at least one update cycle later.
To make this sort of thing work, you need to execute doStuff() asynchronously. Some code that does this might look like this:
private function startDoingStuff():void
{
busyIndicator.visible = true;
// dispatch "doStuff" event
dispatchEvent(new Event("doStuff"));
return; // returning here is important don't do stuff here
}
private function onDoStuff(e:Event):void
{
// do stuff;
busyIndicator.visible = false;
}
Another idea is to use Flex's callLater() method to execute your doStuff() method. This should guarantee that doStuff() is executed on the next cycle:
private function startDoingStuff():void
{
busyIndicator.visible = true;
callLater(onDoStuff);
}
private function onDoStuff():void
{
// do stuff
busyIndicator.visible = false;
}