public PreviewModelImpl() {
nodeSupervisor = new NodeSupervisorImpl();
globalEdgeSupervisor = new GlobalEdgeSupervisorImpl();
selfLoopSupervisor = new SelfLoopSupervisorImpl();
uniEdgeSupervisor = new UnidirectionalEdgeSupervisorImpl();
biEdgeSupervisor = new BidirectionalEdgeSupervisorImpl();
undirectedEdgeSupervisor = new UndirectedEdgeSupervisorImpl();
currentPreset = new DefaultPreset();
applyPreset(currentPreset);
}