Example 7.5. Toggling a GroupNodeRealizer's state

public class ToggleOpenClosedStateViewMode extends ViewMode {
  HierarchyManager hm;
  
  public void mouseClicked(MouseEvent ev) {
    // Convert the mouse event's coordinates from view to world coordinates. 
    double x = translateX(ev.getX());
    double y = translateY(ev.getY());
    
    // Retrieve the node that has been hit at the location. 
    Node v = getHitInfo(ev).getHitNode();
    
    // Test if the node is rendered by GroupNodeRealizer. 
    GroupNodeRealizer gnr = getGroupNodeRealizer(v);
    if (gnr != null) {
      // Get the state label. 
      NodeLabel stateLabel = gnr.getStateLabel();
      // Test, if the mouse event occured on the state icon. 
      if (stateLabel.getBox().contains(x, y)) {
        // Retrieve the HierarchyManager of the grouped graph.
        hm = HierarchyManager.getInstance(view.getGraph2D());
        
        if (hm.isFolderNode(v)) {
          // Invokes a customized OpenFolders Action implementation.
          createOpenFoldersAction(v).openFolders(view);
        }
        else {
          // Invokes a customized CloseGroups Action implementation.
          createCloseGroupsAction(v).closeGroups(view);
        }
      }
    }
  }
}