Fix potential endless loop in layout

Usecase:
- No scrollbar is shown
- Window size will be decreased so that a scrollbar gets necessary

The decreased window size minus the space required for the scrollbar
results in a relayout of the items. In 99 % of all
cases a decreased window size won't result in showing more items in parallel in
comparison to a larger window size. However in the remaining 1 % this can
happen (e.g. see bug 293318 for a sample). This results in an endless loop as
now no scrollbar is required anymore, the layout changes again, the scrollbar
is required again, ...

BUG: 293318
FIXED-IN: 4.8.1

1 files changed, 8 insertions, 0 deletions

diff --git a/src/kitemviews/kitemlistview.h b/src/kitemviews/kitemlistview.h
index 9c34daba3..e675df221 100644
--- a/src/kitemviews/kitemlistview.h
+++ b/src/kitemviews/kitemlistview.h
@@ -462,6 +462,13 @@ private:
     bool animateChangedItemCount(int changedItemCount) const;
 
     /**
+     * @return True if a scrollbar for the given scroll-orientation is required
+     *         when using a size of \p size for the view. Calling the method is rather
+     *         expansive as a temporary relayout needs to be done.
+     */
+    bool scrollBarRequired(const QSizeF& size) const;
+
+    /**
      * Helper function for triggerAutoScrolling().
      * @param pos    Logical position of the mouse relative to the range.
      * @param range  Range of the visible area.
@@ -512,6 +519,7 @@ private:
     KItemListHeader* m_header;
     bool m_useHeaderWidths;
 
+    friend class KItemListContainer; // Accesses scrollBarRequired()
     friend class KItemListController;
     friend class KItemListControllerTest;
 };