Fix QListWidget scrolling with keys when there are hidden items

If the selected item is scrolled with keyboard keys the selected item
will go outside the visible area. The scrolling did not take hidden
items into account when calculating the amout to be scrolled.

Backported from Qt5 commit:
d4385e48b8566a5587048a3c6d8b2396ba587ed5

Task-number: QTBUG-21804
Change-Id: I81a82ed56bb0e4c0229fd117784790e1234aacca
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>

1 files changed, 11 insertions, 3 deletions

diff --git a/src/gui/itemviews/qlistview.cpp b/src/gui/itemviews/qlistview.cpp
index 6db979c80d..e6949fda9f 100644
--- a/src/gui/itemviews/qlistview.cpp
+++ b/src/gui/itemviews/qlistview.cpp
@@ -2558,13 +2558,21 @@ int QListModeViewBase::perItemScrollToValue(int index, int scrollValue, int view
 {
     if (index < 0)
         return scrollValue;
+
+    QVector<int> visibleFlowPositions;
+    visibleFlowPositions.reserve(flowPositions.count() - 1);
+    for (int i = 0; i < flowPositions.count() - 1; i++) { // flowPositions count is +1 larger than actual row count
+        if (!isHidden(i))
+            visibleFlowPositions.append(flowPositions.at(i));
+    }
+
     if (!wrap) {
         int topIndex = index;
         const int bottomIndex = topIndex;
-        const int bottomCoordinate = flowPositions.at(index);
+        const int bottomCoordinate = visibleFlowPositions.at(index);
 
         while (topIndex > 0 &&
-            (bottomCoordinate - flowPositions.at(topIndex-1) + itemExtent) <= (viewportSize)) {
+               (bottomCoordinate - visibleFlowPositions.at(topIndex - 1) + itemExtent) <= (viewportSize)) {
             topIndex--;
         }
 
@@ -2584,7 +2592,7 @@ int QListModeViewBase::perItemScrollToValue(int index, int scrollValue, int view
                                            ? Qt::Horizontal : Qt::Vertical);
         if (flowOrientation == orientation) { // scrolling in the "flow" direction
             // ### wrapped scrolling in the flow direction
-            return flowPositions.at(index); // ### always pixel based for now
+            return visibleFlowPositions.at(index); // ### always pixel based for now
         } else if (!segmentStartRows.isEmpty()) { // we are scrolling in the "segment" direction
             int segment = qBinarySearch<int>(segmentStartRows, index, 0, segmentStartRows.count() - 1);
             int leftSegment = segment;