George Siggouroglou George Siggouroglou - 3 months ago 48
Java Question

Disable TreeItem's default expand/collapse on double click JavaFX 2.2

I am working on a JavaFX 2.2 project and i want to set custom handling of the mouse (double) click event on a TreeItem. Using treeview.setOnMouseClicked i fire my code without errors but the problem is that the TreeItem, on every mouse double click, it toggles between expanded and collapsed. I suppose that this is the default behavior, but how i disable it??

Answer

I had the same issue and solved it in time using EventDispatcher.

class TreeMouseEventDispatcher implements EventDispatcher {
    private final EventDispatcher originalDispatcher;

    public TreeMouseEventDispatcher(EventDispatcher originalDispatcher) {
      this.originalDispatcher = originalDispatcher;
    }

    @Override
    public Event dispatchEvent(Event event, EventDispatchChain tail) {
        if (event instanceof MouseEvent) {
           if (((MouseEvent) event).getButton() == MouseButton.PRIMARY
               && ((MouseEvent) event).getClickCount() >= 2) {

             if (!event.isConsumed()) {
               // Implement your double-click behavior here, even your
               // MouseEvent handlers will be ignored, i.e., the event consumed!
             }

             event.consume();
           }
        }
        return originalDispatcher.dispatchEvent(event, tail);
    }
}

and then use this TreeMouseEventDispatcher for the TreeCell:

treeView.setCellFactory(new Callback<TreeView<T>, TreeCell<T>>() {
  @Override
  public TreeCell<T> call(TreeView<T> param) {
    return new TreeCell<T>() {
      @Override
      protected void updateItem(T item, boolean empty) {
        if (item != null && !empty) {
          EventDispatcher originalDispatcher = getEventDispatcher();
          setEventDispatcher(new TreeMouseEventDispatcher(originalDispatcher));
        }
      }
    };
  }
}
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