public void AddUndoItem(IUndoItem undoEvent)
{
if (Working)
{
return;
}
bool emptyBefore = (_batch?.Count ?? 0) == 0 && !_undoEvents.Any();
if (_batch != null)
{
_batch.Add(undoEvent);
}
else
{
ClearRedoHistory();
_undoEvents.Push(undoEvent);
if (_undoEvents.Count > MAX_UNDO_ITEMS)
{
// XXX: we throw away the current item? this should be a Dequeue so we can pop the front
_undoEvents.Pop();
}
}
if (emptyBefore)
{
// no longer empty
NonEmpty?.Invoke(this, EventArgs.Empty);
}
}
public void CloseBatch()
{
if (_batch == null)
{
return;
}
if (_batch.Count > 0)
{
bool emptyBefore = !_undoEvents.Any();
_undoEvents.Push(_batch);
if (emptyBefore)
{
// no longer empty
NonEmpty?.Invoke(this, EventArgs.Empty);
}
}
_batch = null;
}
/// <summary>
/// Rollback the last undone command.
/// </summary>
public void Redo()
{
if (!CanRedo)
{
return;
}
Working = true;
IUndoItem redo = _redoEvents.Pop();
redo.Do();
bool emptyBefore = !_undoEvents.Any();
_undoEvents.Push(redo);
Working = false;
if (emptyBefore)
{
NonEmpty?.Invoke(this, EventArgs.Empty);
}
}