private IEnumerable <IOleUndoUnit> GetUndoUnits(IOleUndoManager undoManager)
{
IEnumOleUndoUnits undoUnitEnumerator;
try
{
// Unfortunately, EnumUndoable returns the units in oldest-first order.
undoManager.EnumUndoable(out undoUnitEnumerator);
}
catch (COMException)
{
yield break;
}
const int BatchSize = 100;
IOleUndoUnit[] fetchedUndoUnits = new IOleUndoUnit[BatchSize];
while (true)
{
undoUnitEnumerator.Next(BatchSize, fetchedUndoUnits, out var fetchedCount);
for (int i = 0; i < fetchedCount; i++)
{
yield return(fetchedUndoUnits[i]);
}
if (fetchedCount < BatchSize)
{
break;
}
}
}
/// <summary>
/// Removes top 'count' items from given undo manager stack, returning removed undo units in a list.
/// </summary>
public static List <IOleUndoUnit> RemoveTopFromUndoStack(this IOleUndoManager undoManager, int count)
{
if (undoManager == null)
{
throw new ArgumentNullException("undoManager");
}
if (count < 0)
{
throw new ArgumentException("Count must be greater than or equal to zero.");
}
IEnumOleUndoUnits enumerator;
undoManager.EnumUndoable(out enumerator);
if (enumerator == null)
{
throw new InvalidOperationException("Undo manager seems to be incorrectly implemented.");
}
return(RemoveTop(undoManager, enumerator, count));
}
public void EnumUndoable(out IEnumOleUndoUnits ppEnum)
{
_wrappedUndoManager.EnumUndoable(out ppEnum);
}
