moveTo method

bool moveTo(TKey key, TKey? newParent, { required int index, bool animate = true, })

Commits a programmatic move of key under newParent at index, exactly as a pointer drop would: same mutation choice, same live-space final-list index convention, same onReorder report.

Returns false, mutating and notifying NOTHING, when:

• a drag session is active (see below);
• key is absent or pending deletion;
• newParent is absent, pending deletion, key itself, or one of key's descendants;
• canAcceptDrop rejects the destination;
• key already occupies that slot.

Refused during a drag on purpose. Mutating structure underneath a live session leaves it resolving against painted offsets that predate the change, collides with the commit script's first-wins FLIP baseline, and can strand the make-room gap on a slot that no longer exists. Callers that genuinely want to interrupt a drag should cancelDrag first.

Implementation

bool moveTo(
  TKey key,
  TKey? newParent, {
  required int index,
  bool animate = true,
}) {
  if (_session != null) {
    return false;
  }
  if (!_canCommit(key, newParent)) {
    return false;
  }
  // Resolve the index the way [_applyMove] will, so an out-of-range
  // request that clamps onto the node's current slot is recognised as
  // the no-op it is rather than reported as a move.
  final sameParent = treeController.getParent(key) == newParent;
  final int destinationLength = newParent == null
      ? treeController.liveRootCount
      : treeController.liveChildCount(newParent);
  // The FINAL list excludes `key` only when it is already there.
  final effectiveIndex = index.clamp(
    0,
    sameParent ? destinationLength - 1 : destinationLength,
  );
  if (sameParent && treeController.getIndexInParent(key) == effectiveIndex) {
    return false;
  }
  if (canAcceptDrop != null &&
      !canAcceptDrop!(
        movingKey: key,
        newParent: newParent,
        index: effectiveIndex,
      )) {
    return false;
  }
  _fireOnReorder(
    _applyMove(key, newParent, effectiveIndex, animate: animate),
  );
  return true;
}