Android : Catch mouse wheel button pressed/released before activity stops

Question

I'm developing an Android app in Java which must detect events from a real mouse connected in USB, and send them over the network to a computer which will use those events.

My problem : I can detect mouse wheel button events (scroll, pressed, released), but when the user presses the wheel button, the app exits, and the callback is called afterwards.

My question : is it possible to catch the event before the app exits, and prevent the default behavior ? If so, how ? Why do I catch the event too late ?

Here is the functios declared in my activity :

 @Override
 public boolean onGenericMotionEvent(MotionEvent event) {
    int action = MotionEventCompat.getActionMasked(event);
    int pointerId = event.getPointerId(0);

    if (event.getAction() == MotionEvent.ACTION_HOVER_MOVE) {
        Log.d(name, "onGenericMotionEvent : MotionEvent.ACTION_HOVER_MOVE " + MotionEvent.ACTION_HOVER_MOVE);
        return true;
    } else if (event.getAction() == MotionEvent.ACTION_SCROLL) {
        Log.d(name, "onGenericMotionEvent : MotionEvent.ACTION_SCROLL " + MotionEvent.ACTION_SCROLL);
        return true;
    } else if (event.getAction() == MotionEvent.ACTION_HOVER_EXIT) {
        Log.d(name, "why does is happen after onPause ??? onGenericMotionEvent : MotionEvent.ACTION_HOVER_EXIT " + MotionEvent.ACTION_HOVER_EXIT);
        return true;
    } else {
        //Log.d(name, "onGenericMotionEvent : " + MotionEvent.actionToString(event.getAction()) + " " + event.getAction());
    }
    return super.onGenericMotionEvent(event);
}

And here is how I prevented mouse right click from closing the app : public boolean onKeyUp(int keyCode, KeyEvent event) { int source = event.getSource();

    boolean mouseRightButton = false;

    if (source == InputDevice.SOURCE_TOUCHSCREEN) {
        Log.e(name, "onKeyUp from touchscreen");
    } else if (source == InputDevice.SOURCE_MOUSE) {
        Log.e(name, "onKeyUp from mouse");
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            Log.e(name, "right click");
            mouseRightButton = true;
            return true;
        }
    } 
}

Thanks for your help

Answer 1

Return true if you have handled the event. Don't propagate it forward. The app will not close that way.