node.add() method causes break in linking tree lines: File explorer example

[Uche01]

I am adding nodes directly to a parent using method: node.add(). Items are added but the lines showing node link appears to break for the newly added node. See code and image below: node.add(SeasonNode());

[pdsliuzhen]

I have also encountered this problem, may I ask if the problem has been solved

[Michal-MK]

I solved it by cloing the repo and adding

  void fixLastChild() {
    for (var i = 0; i < childrenAsList.length; i++) {
      if (childrenAsList[i] is TreeNode) {
        (childrenAsList[i] as TreeNode).isLastChild = i == childrenAsList.length - 1;
      }
    }
  }

to listenable_node.dart and altering all the add addAll remove etc.. to call it after the super calls.

Then in _IndentationPainter I added an extra parameter isLastChild and initialize it from the node in constructor. Taking it from the node itself did not work for me.

return CustomPaint(
      foregroundPainter: _IndentationPainter(
        indentation: indentation,
        node: node,
        isLastChild: node.isLastChild,
        minLevelToIndent: minLevelToIndent,
      ),
      child: content,
    );

And alter it's shouldRepaint

   @override
  bool shouldRepaint(_IndentationPainter oldDelegate) {
    return indentation != oldDelegate.indentation || node != oldDelegate.node || isLastChild != oldDelegate.isLastChild;
  }

Do not that it is O(n) for every operation so for large trees may be inadequate. It works for my specific usecase.

[olerhan]

I'm not sure if this error originated from me, but seeing this error here made me start thinking that it was caused by the package. My solution was different. I created the following special methods. It's easier than the method above and I think it will work for everyone facing this problem. It worked for me.

  Future<void> insertNodeBelow(IndexedTreeNode<dynamic> referenceNode,
      IndexedTreeNode<dynamic> newNode) async {
    if (referenceNode.isLastChild) {
      referenceNode.isLastChild = false;
      newNode.isLastChild = true;
    }
    referenceNode.parent?.insertAfter(referenceNode, newNode);
//my code
  }

and...

  Future<void> addNode(
      IndexedTreeNode<dynamic> parent, IndexedTreeNode<dynamic> newNode) async {
    for (final child in parent.children) {
      if (child is IndexedTreeNode<dynamic>) {
        child.isLastChild = false;
      }
    }
    newNode.isLastChild = true;
    parent.add(newNode);
//my code
  }

This is it.

I hope the package owner does something to fix these bugs.