public void SetCurrentAsSaveState()
{
if (undoList.Count > 0)
{
lastSaveState = undoList.Last();
}
}
// return reversed command for Undo. Redo is not reversed
static public UndoableCommand GetReversedForUndo(UndoableCommand command)
{
UndoableCommand reversed = null;
if (command.type == UndoableCommandType.InsertComponent)
{
reversed = command.Clone() as UndoableCommand;
reversed.type = UndoableCommandType.DeleteComponent;
}
else if (command.type == UndoableCommandType.DeleteComponent)
{
reversed = command.Clone() as UndoableCommand;
reversed.type = UndoableCommandType.InsertComponent;
}
else if (command.type == UndoableCommandType.ChangeComponentProperty)
{
reversed = UndoableCommand_Property.GetReversed(command as UndoableCommand_Property);
}
else if (command.type == UndoableCommandType.RoutedCommand)
{
reversed = UndoableCommand_Routed.GetReversed(command as UndoableCommand_Routed);
}
else
{
throw new Exception(String.Format("Command type {0} cannot be reversed", command.type));
}
return(reversed);
}
public UndoableCommand Redo()
{
if (redoList.Count == 0)
{
return(null);
}
UndoableCommand command = redoList.Last();
redoList.RemoveLast();
// when Redoing, push the command back to Undo list
undoList.AddLast(command);
CommandManager.InvalidateRequerySuggested();
return(command);
}
public void PushCommand(UndoableCommand command)
{
undoList.AddLast(command);
if (undoList.Count > MAX_STATES)
{
// if over capacity, remove old command
if (lastSaveState != null && undoList.First() == lastSaveState)
{
lastSaveState = null;
}
undoList.RemoveFirst();
}
// when pushing a command, the redo list always becomes empty
redoList.Clear();
CommandManager.InvalidateRequerySuggested();
}
