@Override
  protected double calcZoom(final double zoom, final int amount) {
    if (amount > 0) {
      final double minzoom = ZoomHelpers.getMinimumZoom(m_zyGraph.getView());

      setMinimumZoom(minzoom);

      final double zoomfactor =
          1 - (m_zyGraph.getSettings().getMouseSettings().getZoomSensitivity() * ZOOM_SUB_FACTOR);

      if (minzoom > 0.5) {
        super.setMinimumZoom(0.75);

        return m_zyGraph.getView().getZoom() * zoomfactor;
      }

      return Math.max(m_zyGraph.getView().getZoom() * zoomfactor, minzoom);
    }

    final double zoomfactor =
        1 + (m_zyGraph.getSettings().getMouseSettings().getZoomSensitivity() * ZOOM_SUB_FACTOR);

    // zoom out
    setMaximumZoom(ZoomHelpers.MAX_ZOOM);

    return m_zyGraph.getView().getZoom() * zoomfactor;
  }
Listens to mouse wheel events in edit mode.
java/zylib/src/main/java/com/google/security/zynamics/zylib/yfileswrap/gui/zygraph/editmode/ZyEditModeMouseWheelListener.java