Don't animate items if the number of grid elements has been changed

Having animated items is useful when e.g. deleting or inserting one
item or when the size or position slightly changes by increasing the
zoom level or the window size. However if the number of rows or columns
change, the animation gets obtrusive and in this case lets just apply
the final layout.

1 files changed, 20 insertions, 2 deletions

diff --git a/src/kitemviews/kitemlistview.h b/src/kitemviews/kitemlistview.h
index 4455166dd..95215fffd 100644
--- a/src/kitemviews/kitemlistview.h
+++ b/src/kitemviews/kitemlistview.h
@@ -347,10 +347,13 @@ private:
     /**
      * Helper method for doLayout: Returns a list of items that can be reused for the visible
      * area. Invisible group headers get recycled. The reusable items are items that are
-     * invisible and not animated. Reusing items is faster in comparison to deleting invisible
+     * invisible. If the animation hint is 'Animation' then items that are currently animated
+     * won't be reused. Reusing items is faster in comparison to deleting invisible
      * items and creating a new instance for visible items.
      */
-    QList<int> recycleInvisibleItems(int firstVisibleIndex, int lastVisibleIndex);
+    QList<int> recycleInvisibleItems(int firstVisibleIndex,
+                                     int lastVisibleIndex,
+                                     LayoutAnimationHint hint);
 
     /**
      * Helper method for doLayout: Starts a moving-animation for the widget to the given
@@ -442,6 +445,21 @@ private:
      *         if no header is shown.
      */
     QRectF headerBoundaries() const;
+    
+    /**
+     * @return True if the number of columns or rows will be changed when applying
+     *         the new grid- and item-size. Used to determine whether an animation
+     *         should be done when applying the new layout.
+     */
+    bool changesItemGridLayout(const QSizeF& newGridSize, const QSizeF& newItemSize) const;
+    
+    /**
+     * @param changedItemCount Number of inserted  or removed items.
+     * @return                 True if the inserting or removing of items should be animated.
+     *                         No animation should be done if the number of items is too large
+     *                         to provide a pleasant animation.
+     */
+    bool animateChangedItemCount(int changedItemCount) const;
 
     /**
      * Helper function for triggerAutoScrolling().