Correct handling of OnMouseWheel events in Ext-GWT

Question

I'm trying to figure out which property of BoxComponentEvent will tell me if the generated OnMouseWheel event was a scroll-up or scroll-down event. I have output the values of all the properties BoxComponentEvent exposes; and all of them (with the exception of the coordinates at which the event took place) stay the same regardless. Google and the Ext-GWT docs have been pretty useless for providing a concrete example.

public class MyPanel extends ContentPanel {
    // ...
    public MyPanel() {
     addListener(Events.OnMouseWheel, new Listener<BoxComponentEvent>() {
      public void handleEvent(BoxComponentEvent be) {
       // What happens here to distinguish scroll-up and scroll-down?
      }
     });
    }

    protected void afterRender() {
     super.afterRender();
     el().addEventsSunk(Events.OnMouseWheel.getEventCode());
    }
    // ...
}

Answer 1

Hi Kevin, I tested this and it works:

private int vpos = 0;
public MyPanel() {
     ContentPanel contents = new ContentPanel();
     contents.setHeight(500);

     add(new Label("This is MyPanel"));
     add(contents);
     setHeight(300);
     setScrollMode(Scroll.ALWAYS);
     vpos = getVScrollPosition();

     addListener(Events.Scroll, new Listener<BaseEvent>(){

      @Override
      public void handleEvent(BaseEvent be) {

       int newVpos = getVScrollPosition();
       if(newVpos<vpos){
        Info.display("DEBUG", "UP!");
       } else if(newVpos>vpos){
        Info.display("DEBUG", "DOWN!");
       }
       vpos = newVpos;

      }});
    }