moveItem method

void moveItem(K itemKey, { K? toSection, int? index, bool animate = true, Duration? slideDuration, Curve? slideCurve, })

Repositions itemKey, either across sections or within its own.

• toSection non-null → reparents the item under that section. With index it lands at that position; without, it is appended. • toSection null, index non-null → reorders the item within its current section to index. • both null → no-op.

When animate is true (the default), a cross-section reparent runs a paint-only FLIP slide on the moved row from its old painted position to its new one, using slideDuration / slideCurve. Both default to the controller's animationDuration / animationCurve so the slide stays in sync with the inserts / removes / expands / collapses that may compose with it inside the same runBatch.

In-section reorders are pure repositioning ops that never animate regardless of animate — neighbouring rows shift in place, the underlying TreeController.reorderChildren does not produce per-row enter/exit animations.

Implementation

void moveItem(
  K itemKey, {
  K? toSection,
  int? index,
  bool animate = true,
  Duration? slideDuration,
  Curve? slideCurve,
}) {
  _checkNotDisposed();
  _requireItem(itemKey, "moveItem");
  if (toSection != null) {
    _requireSection(toSection, "moveItem(toSection)");
    _tree.moveNode(
      ItemKey<K>(itemKey),
      SectionKey<K>(toSection),
      index: index,
      animate: animate,
      slideDuration: slideDuration ?? _tree.animationDuration,
      slideCurve: slideCurve ?? _tree.animationCurve,
    );
    return;
  }
  if (index == null) {
    // Neither a reparent target nor a reorder index — nothing to do.
    return;
  }
  if (_tree.isPendingDeletion(ItemKey<K>(itemKey))) {
    _throwMissing("moveItem", "item $itemKey is being removed");
  }
  final parentKey = sectionOf(itemKey);
  if (parentKey == null) {
    _throwMissing("moveItem", "item $itemKey has no parent section");
  }
  // Use the LIVE list — `reorderItems` → `_tree.reorderChildren`
  // validates against the live child set (excludes pending-deletion).
  final siblings = itemKeysOf(parentKey)..remove(itemKey);
  final clamped = index.clamp(0, siblings.length);
  siblings.insert(clamped, itemKey);
  reorderItems(parentKey, siblings);
}