/// <summary>
/// Manages the Redo Stack.
/// </summary>
/// <param name="index">The index to be used as the SelectionStart attribute.</param>
/// <returns>RTF string.</returns>
public string RedoCommand(out int index)
{
if (_redoStack.IsEmpty())
{
index = 0;
return(null);
}
string rtf = _redoStack.Pop(out index);
//avoid repeating the insertion if _lastRemovedRtf when Redo is clicked multiple times
if (!_lastUndoActionName.Equals("Redo") && !string.IsNullOrEmpty(_lastRemovedRtf) && !_undoStack.Top().Equals(_lastRemovedRtf))
{
_undoStack.Push(_lastRemovedRtf, _lastIndex);
}
//avoid inserting the same value two times to the top of the stack
if (!_undoStack.Top().Equals(rtf))
{
_undoStack.Push(rtf, index);
}
_lastUndoActionName = "Redo";
return(rtf);
}
/// <summary>
/// Manages the Undo Stack.
/// </summary>
/// <param name="index">The index to be used as the SelectionStart attribute.</param>
/// <param name="canRedo">Identifies if the command can be redone.</param>
/// <returns>RTF string.</returns>
public string RemoveCommand(out int index, bool canRedo)
{
string removedRtf = _undoStack.Pop(out index);
if (_lastUndoActionName.Equals("Undo") && canRedo && !string.IsNullOrEmpty(_lastRemovedRtf) && !_undoStack.IsEmpty() &&
!_redoStack.Top().Equals(_lastRemovedRtf))
{
_redoStack.Push(_lastRemovedRtf, _lastIndex);
}
else if (canRedo && !string.IsNullOrEmpty(removedRtf.Trim()))
{
_redoStack.Push(removedRtf, index);
}
else if (!string.IsNullOrEmpty(removedRtf.Trim()))
{
_redoStack.Push(removedRtf, index);
}
if (_undoStack.IsEmpty())
{
_undoStack.Push(string.Empty, 0);
}
_lastUndoActionName = "Undo";
_lastRemovedRtf = removedRtf;
_lastIndex = index;
return(_lastRemovedRtf);
}