BiomePainter.History.HistoryManager.Undo C# (CSharp) Метод

        public void Undo(Bitmap selection, RegionFile region, Bitmap terrainOverlay, Bitmap biomeOverlay, ref String[,] tooltips, Bitmap populateOverlay, UpdateStatus updateStatus)
        {
            while (undoStack.Count > 0 && undoStack.Last.Value.PreviousAction == null)
            {
                redoStack.AddLast(undoStack.Last.Value);
                undoStack.RemoveLast();
            }

            if (undoStack.Count == 0)
                return;

            IAction previous = undoStack.Last.Value.PreviousAction;
            if (previous == null)
            {
                throw new Exception("Undo sanity check failed.");
            }

            if (previous is SelectionAction)
            {
                ApplySelectionState((SelectionAction)previous, selection);
            }
            else if (previous is BiomeAction)
            {
                ApplyBiomeState((BiomeAction)previous, region, terrainOverlay, biomeOverlay, ref tooltips, updateStatus);
            }
            else if (previous is PopulateAction)
            {
                ApplyPopulateState((PopulateAction)previous, region, populateOverlay);
            }

            MovePrevious();
            OnChange();
        }