if (!visibleAtPreviousScale && isShowing()) {
visibleAtPreviousScale = true;
eventBus.fireEvent(new LayerShowEvent(AbstractLayer.this));
} else if (visibleAtPreviousScale && !isShowing()) {
visibleAtPreviousScale = false;
eventBus.fireEvent(new LayerHideEvent(AbstractLayer.this));
}
}