Fix hover handling in QTreeView

Cached hoverBranch could get invalid if branches were collapsed or
expanded programmatically, leading to a crash in some situations.

Fixed the logic for updating hovered over branch indicators and
also now update hoverBranch when drawing so that it is guaranteed to be
up to date there - this fixes issues like hover indicator not updating
when the view is programmatically scrolled.

Task-number: QTBUG-27158
Change-Id: I5bd1ad76aee512ad78df33959a84ead16886a47c
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>

1 files changed, 11 insertions, 13 deletions

diff --git a/src/widgets/itemviews/qtreeview.cpp b/src/widgets/itemviews/qtreeview.cpp
index b10933f13b..b6ca379bf3 100644
--- a/src/widgets/itemviews/qtreeview.cpp
+++ b/src/widgets/itemviews/qtreeview.cpp
@@ -1241,19 +1241,14 @@ bool QTreeView::viewportEvent(QEvent *event)
         QHoverEvent *he = static_cast<QHoverEvent*>(event);
         int oldBranch = d->hoverBranch;
         d->hoverBranch = d->itemDecorationAt(he->pos());
-        if (oldBranch != d->hoverBranch) {
-            //we need to paint the whole items (including the decoration) so that when the user
-            //moves the mouse over those elements they are updated
-            if (oldBranch >= 0) {
-                int y = d->coordinateForItem(oldBranch);
-                int h = d->itemHeight(oldBranch);
-                viewport()->update(QRect(0, y, viewport()->width(), h));
-            }
-            if (d->hoverBranch >= 0) {
-                int y = d->coordinateForItem(d->hoverBranch);
-                int h = d->itemHeight(d->hoverBranch);
-                viewport()->update(QRect(0, y, viewport()->width(), h));
-            }
+        QModelIndex newIndex = indexAt(he->pos());
+        if (d->hover != newIndex || d->hoverBranch != oldBranch) {
+            // Update the whole hovered over row. No need to update the old hovered
+            // row, that is taken care in superclass hover handling.
+            QRect rect = visualRect(newIndex);
+            rect.setX(0);
+            rect.setWidth(viewport()->width());
+            viewport()->update(rect);
         }
         break; }
     default:
@@ -1419,6 +1414,9 @@ void QTreeView::drawTree(QPainter *painter, const QRegion &region) const
 
     const int viewportWidth = d->viewport->width();
 
+    QPoint hoverPos = d->viewport->mapFromGlobal(QCursor::pos());
+    d->hoverBranch = d->itemDecorationAt(hoverPos);
+
     QVector<QRect> rects = region.rects();
     QVector<int> drawn;
     bool multipleRects = (rects.size() > 1);