private ArrayList CopyUndoUnitsToArray(IEnumOleUndoUnits undoUnits)
{
// get a list of all of the undo units
ArrayList undoUnitArray = new ArrayList();
IOleUndoUnit current;
int result;
while ((result = undoUnits.Next(1, out current, IntPtr.Zero)) == HRESULT.S_OK)
undoUnitArray.Add(current);
// return the list in an array
return undoUnitArray;
}
private static List <IOleUndoUnit> RemoveTop(IOleUndoManager undoManager, IEnumOleUndoUnits enumerator, int count)
{
List <IOleUndoUnit> backupList = new List <IOleUndoUnit>();
List <IOleUndoUnit> returnList = new List <IOleUndoUnit>();
int hr;
if (count > 0)
{
uint returned = 1;
// backup all existing undo units
while (returned > 0)
{
IOleUndoUnit[] units = new IOleUndoUnit[10];
hr = enumerator.Next((uint)units.Length, units, out returned);
Marshal.ThrowExceptionForHR(hr);
if (returned == 10)
{
backupList.AddRange(units);
}
else if (returned > 0)
{
for (int i = 0; i < returned; i++)
{
backupList.Add(units[i]);
}
}
}
// put units back except those which should be removed
if (backupList.Count > 0)
{
PoisonPillUndoUnit pill = new PoisonPillUndoUnit();
undoManager.Add(pill);
// clear stack
undoManager.DiscardFrom(pill);
// add units back
for (int i = 0; i < backupList.Count - count; i++)
{
undoManager.Add(backupList[i]);
}
// return top "count" units or less, if there's not enough
if (count <= backupList.Count)
{
returnList = backupList.GetRange(backupList.Count - count, count);
}
else
{
returnList = backupList;
}
}
}
returnList.Reverse();
return(returnList);
}