Add function KItemListSelectionManager::isSelected(int index)

This function is used in KItemListView::updateWidgetProperties()
to find out if an item is selected in a more efficient way.
The new function is tested in KItemListSelectionManagerTest.
I've factored out some code from
KItemListSelectionManagerTest::testChangeSelection() to a new
member to simplify the test.

1 files changed, 1 insertions, 8 deletions

diff --git a/src/kitemviews/kitemlistview.cpp b/src/kitemviews/kitemlistview.cpp
index d96cf14ce..ad4221394 100644
--- a/src/kitemviews/kitemlistview.cpp
+++ b/src/kitemviews/kitemlistview.cpp
@@ -1393,16 +1393,9 @@ void KItemListView::updateWidgetProperties(KItemListWidget* widget, int index)
 
     const KItemListSelectionManager* selectionManager = m_controller->selectionManager();
     widget->setCurrent(index == selectionManager->currentItem());
-
-    if (selectionManager->hasSelection()) {
-        const QSet<int> selectedItems = selectionManager->selectedItems();
-        widget->setSelected(selectedItems.contains(index));
-    } else {
-        widget->setSelected(false);
-    }
+    widget->setSelected(selectionManager->isSelected(index));
 
     widget->setHovered(false);
-
     widget->setIndex(index);
     widget->setData(m_model->data(index));
 }