JavaFX TreeView: remove expand / collapse button (disclosure node) & functionality

Question

I want to have a TreeView that has all of its children permanently expanded, and I don't want the user to be able to expand or collapse any of the children.

To do this I've found that I need to do the following:

• Remove icon with CSS (Done)
  • Change expand and collapse image TreeView JavaFX 2.2
  • [edit] Above link should be used to change image; to remove completely, use this solution: https://stackoverflow.com/a/27831191/4430591
• Remove double click functionality (Done)
  • Disable TreeItem's default expand/collapse on double click JavaFX 2.2
• [edit] Remove ability to collapse / expand using keyboard arrrow keys (Done)
  • Given in José Pereda's solution below ( https://stackoverflow.com/a/27831085/4430591 )
• [edit] Remove ability to right click for a ContextMenu (Done)
  • Given in José Pereda's solution below ( https://stackoverflow.com/a/27831085/4430591 )
• Remove icon's clickablity (How do I do this?)
  • [edit] solution: https://stackoverflow.com/a/27831191/4430591

Even though the icon is no longer visible, it's still clickable. I don't see any way of filtering this; I only see ways to be able to respond to it after the fact.

Also, if I'm missing anything else that I need to do to ensure this functionality, please let me know.

Answer 1

I feel quite silly. I think this was mostly just a matter of not knowing what that darn arrow was called. Apparently it's a disclosureNode? Maybe that's common knowledge.

In the custom defined TreeCell, all I did was add this line in the updateItem method:

setDisclosureNode(null);

Answer 2

The solution to avoid modifying the skin or the default behavior is more simple if we trap the clicks before they are dispatched, and consume the right ones.

For that we can use an EventDispatcher, to filter both the mouse pressed and the right click over the arrows, which are StackPane nodes:

class CellEventDispatcher implements EventDispatcher {

    private final EventDispatcher original;

    public CellEventDispatcher(EventDispatcher original) {
        this.original = original;
    }

    @Override
    public Event dispatchEvent(Event event, EventDispatchChain tail) {
        if (event.getEventType().equals(MouseEvent.MOUSE_PRESSED) || 
             event.getEventType().equals(ContextMenuEvent.ANY)){
            event.consume();
        }
        if(event instanceof KeyEvent && event.getEventType().equals(KeyEvent.KEY_PRESSED)){
            if((((KeyEvent)event).getCode().equals(KeyCode.LEFT) || 
                 ((KeyEvent)event).getCode().equals(KeyCode.RIGHT))){
                event.consume();
            }
        }
        return original.dispatchEvent(event, tail);
    }
}

Now we apply our custom dispatcher to the tree view:

@Override
public void start(Stage primaryStage) {
    TreeView<String> tree = new TreeView<>();
    ...
    EventDispatcher treeOriginal = tree.getEventDispatcher();
    tree.setEventDispatcher(new CellEventDispatcher(treeOriginal));

    Scene scene = new Scene(tree);
    primaryStage.setScene(scene);
    primaryStage.show(); 
}

This will consume any click (left or right) over the arrows on the tree.

EDIT

Added to the event dispatcher class the case where the user uses the keyboard to traverse the tree view, consuming the collapse/expand events with arrow LEFT or RIGHT.