private void CreateDeltaSelectionChange(List<object> unselectedItems, List<object> selectedItems)
{
for (int i = 0; i < _toDeferSelect.Count; i++)
{
object o = _toDeferSelect[i];
// If defered selected item exis in Items - move it to _toSelect
if (_owner.Items.Contains(o))
{
_toSelect.Add(o);
_toDeferSelect.Remove(o);
i--;
}
}
if (_toUnselect.Count > 0 || _toSelect.Count > 0)
{
if (_owner._selectedItems.UsesItemHashCodes)
{
// Step 1: Keep current selection temp storage
InternalSelectedItemsStorage currentSelectedItems = new InternalSelectedItemsStorage(_owner._selectedItems);
// Step 2: Clear the selection storage
_owner._selectedItems.Clear();
// STep 3: Process the items that need to be unselected
foreach (object o in _toUnselect)
{
_owner.ItemSetIsSelected(o, false);
if (currentSelectedItems.Contains(o))
{
unselectedItems.Add(o);
}
}
// Step 4: Add back items from the temp storage that are not in _toUnselect
foreach (object o in currentSelectedItems)
{
if (!_toUnselect.Contains(o))
{
_owner._selectedItems.Add(o);
}
}
}
else
{
foreach (object o in _toUnselect)
{
_owner.ItemSetIsSelected(o, false);
if (_owner._selectedItems.Contains(o))
{
_owner._selectedItems.Remove(o);
unselectedItems.Add(o);
}
}
}
foreach (object o in _toSelect)
{
_owner.ItemSetIsSelected(o, true);
if (!_owner._selectedItems.Contains(o))
{
_owner._selectedItems.Add(o);
selectedItems.Add(o);
}
}
}
}
private void UpdateSelectedItems()
{
// Update SelectedItems. We don't want to invalidate the property
// because that defeats the ability of bindings to be able to listen
// for collection changes on that collection. Instead we just want
// to add all the items which are not already in the collection.
// Note: This is currently only called from SelectionChanger where SC.IsActive will be true.
// If this is ever called from another location, ensure that SC.IsActive is true.
Debug.Assert(SelectionChange.IsActive, "SelectionChange.IsActive should be true");
IList userSelectedItems = SelectedItemsImpl;
if (userSelectedItems != null)
{
InternalSelectedItemsStorage userSelectedItemsTable = new InternalSelectedItemsStorage(userSelectedItems.Count);
userSelectedItemsTable.UsesItemHashCodes = _selectedItems.UsesItemHashCodes;
for (int i = 0; i < userSelectedItems.Count; i++)
{
object userSelectedItem = userSelectedItems[i];
if (_selectedItems.Contains(userSelectedItem) && !userSelectedItemsTable.Contains(userSelectedItem))
{
// cache the user's selected items into a table with O(1) lookup.
userSelectedItemsTable.Add(userSelectedItem);
}
else
{
// Remove each thing that is in SelectedItems that's not in _selectedItems.
// Remove all duplicate items from userSelectedItems
userSelectedItems.RemoveAt(i);
i--;
}
}
// Add to SelectedItems everything missing that's in _selectedItems.
foreach (object selectedItem in _selectedItems)
{
if (!userSelectedItemsTable.Contains(selectedItem))
{
userSelectedItems.Add(selectedItem);
}
}
}
}