redo method

Implementation

void redo() {
  if (_undoStack[_currentPage]?.isNotEmpty == true) {
    var lastAction = _undoStack[_currentPage]!.removeLast();
    _history[_currentPage]!.add(lastAction);

    if (lastAction.isAdd) {
      _textBoxes[_currentPage]?.add(lastAction.textBox); // Re-add text box.
    } else {
      _textBoxes[_currentPage]?.remove(
        lastAction.textBox,
      ); // Remove text box.
    }
    notifyListeners(); // Notify listeners after redo.
  }
}