internal override void OnSelectedItemChanged(object oldSelectedItem, object selectedItem)
{
if (_modifyingSelectionInternally)
{
return;
}
if (IsSelectionMultiple)
{
var items = GetItems();
if (selectedItem == null || items.Contains(selectedItem))
{
object[] removedItems = null;
object[] addedItems = null;
try
{
_modifyingSelectionInternally = true;
removedItems = SelectedItems.Except(selectedItem).ToObjectArray();
var isRealSelection = selectedItem != null || items.Contains(null);
addedItems = SelectedItems.Contains(selectedItem) || !isRealSelection ? new object[0] : new[] { selectedItem };
SelectedItems.Clear();
if (isRealSelection)
{
SelectedItems.Add(selectedItem);
}
}
finally
{
_modifyingSelectionInternally = false;
}
//Invoke event after resetting flag, in case callbacks in user code modify the collection
if (addedItems.Length > 0 || removedItems.Length > 0)
{
InvokeSelectionChanged(removedItems, addedItems);
}
}
else
{
SelectedItem = oldSelectedItem;
}
}
else
{
SelectedItems.Clear();
SelectedItems.Add(selectedItem);
base.OnSelectedItemChanged(oldSelectedItem, selectedItem);
}
}
private void UpdateElements(ISet <FrameworkElement> selectedItems)
{
var added = selectedItems.Except(SelectedItems);
var removed = SelectedItems.Except(selectedItems);
foreach (var element in added)
{
element.SetValue(TargetSelectionProperty, true);
}
foreach (var element in removed)
{
element.SetValue(TargetSelectionProperty, false);
}
SelectedItems = selectedItems;
}
private void NewSelection(T selectedItem)
{
if (multiModifierDown)
{
if (SelectedItems.Add(selectedItem))
{
Selection?.Invoke(this, new ItemSelectionEventArgs <T>(selectedItem, SelectionType.Selected));
}
}
else
{
bool alreadySelected = SelectedItems.Contains(selectedItem);
var toRemove = SelectedItems.Except(selectedItem).ToArray();
foreach (var b in toRemove)
{
Deselect(b);
}
if (!alreadySelected)
{
SelectedItems.Add(selectedItem);
Selection?.Invoke(this, new ItemSelectionEventArgs <T>(selectedItem, SelectionType.Selected));
}
}
}
