private void SetStart()
{
redoStack.Clear();
UndoBatch b = UndoHead;
if (b == null)
{
b = new UndoBatch();
undoStack.Push(b);
}
if (b.IsEmpty && context != null)
{
b.Start = context.ContextInfo;
}
}
public object Undo(object info)
{
if (!CanUndo)
{
throw new InvalidOperationException("Cannot undo");
}
if (UndoHead != null && UndoHead.IsEmpty)
{
// ignore an empty batch
undoStack.Pop();
}
Debug.Assert(UndoHead != null && !UndoHead.IsEmpty, "Invalid undo state");
UndoBatch batch = (UndoBatch)undoStack.Pop();
if (batch.End == null)
{
batch.End = info;
}
disabled = true;
try
{
batch.Undo();
}
finally
{
disabled = false;
}
redoStack.Push(batch);
if (undoStack.Count == 0 || !UndoHead.IsEmpty)
{
// undo stack is empty or there is a non-empty batch on the undo
// stack - we want to separate any future changes from that batch
UndoBatch n = new UndoBatch();
// TODO: M: not sure about this next line
// consider edit, undo, move, edit, undo
n.Start = batch.Start;
undoStack.Push(n);
}
return(batch.Start);
}
public void Mark(object info)
{
// Console.WriteLine("UndoManager: Mark({0})", info);
UndoBatch batch = UndoHead;
if (batch != null)
{
if (batch.IsEmpty)
{
return;
}
if (batch.End == null)
{
batch.End = info;
}
}
batch = new UndoBatch();
undoStack.Push(batch);
}
public object Redo()
{
if (!CanRedo)
{
throw new InvalidOperationException("Cannot redo");
}
UndoBatch batch = (UndoBatch)redoStack.Pop();
disabled = true;
try
{
batch.Redo();
undoStack.Push(batch);
UndoBatch n = new UndoBatch();
n.Start = batch.End;
undoStack.Push(n);
}
finally
{
disabled = false;
}
return(batch.End);
}
