Question

I have a custom event class

public class FFTDrawEvent extends Event {

    public static const DRAW_EVENT:String = "drawEvent";

    private var _param:Array = new Array();

    public function FFTDrawEvent(type:String, __param:Array, bubbles:Boolean=true, cancelable:Boolean=false) {
        _param = __param;
        super(type, bubbles, cancelable);
    }

    public function get param():Array {
        return _param;
    }
}

This event is dispatched by a class, that extends EventDispatcher:

public class ToneGenerator extends EventDispatcher {

 public function someFunction():void {

 this.dispatchEvent(new FFTDrawEvent(FFTDrawEvent.DRAW_EVENT,_param));
}

Another class listen to this event. This class is extending SpriteVisualElement.

public class SpectrumVisualizer extends `SpriteVisualElement`:
{
    public function SpectrumVisualizer()
    {
        this.addEventListener(FFTDrawEvent.DRAW_EVENT, draw);
    }

Unfortunately this doesn’t work. The event is dispatched (returns with true), but the Event listener is never triggered.

Both class (Dispatcher & Listener) are Child class of a MXML application. Also listen to the event in the parent MXML application doens’t work. Listen to the event in the dispatching class itself somehow works.

I have to feeling that the EventDispatcher class is not the right one to dispatch events to a mxml application or respectivly AS classes, which extend/inherent from a MXML component class.

Anybody can help me with that?

Answer 1

You should listen for events on the dispatcher. In your case, an instance of ToneGenerator is dispatching the event and SpectrumVisualizer is listening – it wouldn’t work.

Listen to the event in the dispatching class itself somehow works.

That’s the only way it would work.

When you call

this.addEventListener(FFTDrawEvent.DRAW_EVENT, draw);

you are telling this object to call this.draw method whenever it (the this object) dispatches an event of type FFTDrawEvent.DRAW_EVENT. Change it to

toneGen.addEventListener(FFTDrawEvent.DRAW_EVENT, draw);

Now you are telling toneGen object to call this.draw method whenever it (the toneGen object) dispatches an event of type FFTDrawEvent.DRAW_EVENT.

You can also do the following from the parent mxml.

toneGen.addEventListener(FFTDrawEvent.DRAW_EVENT, specVis.draw);

Call specVis.draw method whenever the toneGen object dispatches an event of type FFTDrawEvent.DRAW_EVENT.