private void OnItemDetachedSafe([UsedImplicitly] int index, TItem item)
{
VerifySafe();
if (HasSource)
{
if (IsLocked(item) == false)
{
var source = GetSource(item);
if (MultipleSelection)
{
if (CurrentSelectionCollection.FindBySource(source, out var selection))
{
if (ReferenceEquals(item, selection.Item))
{
CurrentSelectionCollection.UpdateSelection(selection.Index, selection.WithItem(null));
}
}
}
if (ReferenceEquals(source, CurrentSelectedSource))
{
if (ReferenceEquals(item, CurrentSelectedItem))
{
Sync(CurrentSelection.WithItem(null));
}
}
}
}
else
{
if (IsVirtualizing == false)
{
UnselectItemSafe(item);
}
}
}
private void OnItemAttachedSafe(int index, TItem item)
{
VerifySafe();
var itemSelected = GetIsItemSelected(item);
if (HasSource)
{
// TODO Implement Sync mechanism to determine if item source is actually selected.
// TODO For example ListViewItem can have two way binding on IsSelected property to its DataContext and DataContext changes its selection state.
// TODO In this case selected item source will stay in SelectionCollection and code below will behave incorrectly.
// TODO Sync mechanism could be implemented through event in Selector control. As another option check if Item Selection property is bound to Data Context
// TODO and perform immediate update on the binding to update Item IsSelected property.
var source = GetSource(item);
if (MultipleSelection)
{
if (CurrentSelectionCollection.FindBySource(source, out var selection))
{
if (ReferenceEquals(item, selection.Item) == false)
{
CurrentSelectionCollection.UpdateSelection(selection.Index, selection.WithItem(item));
}
}
}
if (ReferenceEquals(source, CurrentSelectedSource))
{
if (ReferenceEquals(item, CurrentSelectedItem) == false)
{
Sync(CurrentSelection.WithItem(item));
}
}
{
var itemSourceInSelection = IsSourceInSelection(source);
if (itemSourceInSelection && itemSelected == false)
{
if (CanSelectItem(item))
{
SetItemSelected(item, true);
}
else
{
UnselectItemSafe(item);
}
}
if (itemSourceInSelection == false && itemSelected)
{
SetItemSelected(item, false);
}
}
}
else
{
if (SupportsIndex)
{
var selectedIndex = CurrentSelectedIndex;
if (selectedIndex != -1)
{
var itemIndex = index == -1 ? GetIndexOfItem(item) : index;
if (MultipleSelection)
{
if (CurrentSelectionCollection.FindByIndex(index, out var selection))
{
if (ReferenceEquals(item, selection.Item) == false)
{
CurrentSelectionCollection.UpdateSelection(selection.Index, selection);
}
}
}
if (selectedIndex == itemIndex)
{
if (ReferenceEquals(item, CurrentSelectedItem) == false)
{
Sync(CurrentSelection.WithItem(item));
}
}
}
}
var itemInSelection = IsItemInSelection(item);
if (itemInSelection && itemSelected == false)
{
if (CanSelectItem(item))
{
SetItemSelected(item, true);
}
else
{
UnselectItemSafe(item);
}
}
if (itemSelected && itemInSelection == false)
{
SelectItemSafe(item);
}
}
}
