/// <summary>
/// Add an undo state to the current stage (if one is active) or directly
/// to the stack as a new stage (if one isn't).
/// </summary>
/// <param name="state"></param>
/// <param name="clearRedo">If true, the redo stack will be invalidated</param>
public void AddUndoState(UndoState state, bool clearRedo = true)
{
if (!Locked && Active)
{
if (state != null && state.IsValid)
{
if (ActiveStage != null)// && !ActiveStage.Contains(state))
{
ActiveStage.Add(state);
if (!UndoStack.Contains(ActiveStage))
{
AddUndoStage(ActiveStage);
}
}
else
{
UndoStage stage = new UndoStage();
stage.Add(state);
AddUndoStage(stage);
}
}
if (clearRedo)
{
RedoStack.Clear();
}
}
}
/// <summary>
/// Revert this stage by restoring the states stored
/// within this collection
/// </summary>
/// <returns>The redo stage necessary to redo this undo.</returns>
public UndoStage Undo()
{
var redo = new UndoStage();
for (int i = Count - 1; i >= 0; i--)
{
UndoState state = this[i];
if (state.IsValid)
{
try
{
redo.Add(state.GenerateRedo());
state.Restore();
}
catch { }
}
}
return redo;
}