/// <summary>
/// Remembers a point that is about to be moved
/// </summary>
/// <param name="p">The point that is about to move</param>
internal void AddMove(PointFeature p)
{
UpdateUndoMarker um = m_Moves.Peek();
Debug.Assert(um != null);
um.AddMove(p);
}
/// <summary>
/// Rolls back changes (moves) that have occurred since the last undo marker (as defined
/// via a prior call to <see cref="SetUndoMarker"/>).
/// </summary>
/// <returns>True if an undo marker was rolled back. False if everything has already
/// been undone.</returns>
internal bool Undo()
{
if (m_Moves.Count == 0)
{
return(false);
}
UpdateUndoMarker um = m_Moves.Pop();
Debug.Assert(um != null);
um.Undo();
return(true);
}
/// <summary>
/// Sets an undo marker to indicate a savepoint that the user may go back to
/// while making a series of editing revisions.
/// </summary>
internal void SetUndoMarker()
{
UpdateUndoMarker um = new UpdateUndoMarker();
if (m_Moves.Count > 0)
{
UpdateUndoMarker lastMarker = m_Moves.Peek();
if (lastMarker != null && lastMarker.EditSequence == um.EditSequence)
{
// If the last marker is empty, just get rid of it (user may have cancelled
// from previous edit)
if (lastMarker.IsEmpty)
{
m_Moves.Pop();
}
else
{
throw new InvalidOperationException("Attempt to create another undo marker for the same edit");
}
}
}
m_Moves.Push(um);
}
