redo method

void redo()

Reapplies drawings to the next forward state in history.

Implementation

void redo() {
  if (!canRedo) return;
  _undoStack.add(_drawings.map((d) => d.copyWith()).toList());
  _drawings
    ..clear()
    ..addAll(_redoStack.removeLast());
  notifyListeners();
  triggerAutoSave();
}