restoreExpansionSnapshot method

Implementation

void restoreExpansionSnapshot(ExpansionSnapshot snapshot) {
  // First, capture what the fresh adapter already has.
  final freshExpanded = expandedNodeIds;
  final freshPartials = <String, Set<String>>{};
  void collectFreshPartials(LayoutNode n) {
    if (n.isPartiallyExpanded) {
      freshPartials[n.id] = Set<String>.from(n.partialChildIds!);
    }
    n.children.forEach(collectFreshPartials);
    if (n.hiddenChildren != null) {
      n.hiddenChildren!.forEach(collectFreshPartials);
    }
  }

  collectFreshPartials(root);

  // Collapse fully-expanded nodes that shouldn't be.
  for (final id in freshExpanded) {
    if (!snapshot.fullyExpanded.contains(id) &&
        !snapshot.partials.containsKey(id)) {
      toggleNode(id);
    }
  }

  // Expand nodes that should be fully expanded but aren't.
  for (final id in snapshot.fullyExpanded) {
    if (!freshExpanded.contains(id)) {
      toggleNode(id);
    }
  }

  // Restore partial expansions.
  for (final entry in snapshot.partials.entries) {
    final node = nodeMap[entry.key];
    if (node == null) {
      continue;
    }
    // If the node is already partially expanded from the fresh adapter,
    // clear it and reapply the snapshot's partial set.
    node
      ..partialChildIds = entry.value.childIds
      ..partialHyperedgeIds = entry.value.edgeIds;
  }

  // Clear any fresh partial expansions not in the snapshot.
  for (final id in freshPartials.keys) {
    if (!snapshot.partials.containsKey(id) &&
        !snapshot.fullyExpanded.contains(id)) {
      nodeMap[id]?.partialChildIds = null;
      nodeMap[id]?.partialHyperedgeIds = null;
    }
  }
}