@Override
    public void mouseWheelMoved(MouseWheelEvent e) {
       int notches = e.getWheelRotation();
       if (!centerZoom) {
            if (notches > 0) map.zoomOutRelativeToMouse(0.05, mousePosX, mousePosY);
            else             map.zoomInRelativeToMouse (0.05, mousePosX, mousePosY);
       } else /* center zoom */ {
            if (notches > 0) map.zoomOut(0.05);
            else             map.zoomIn (0.05);
       }
    }