Don't rely on mapFromGlobal in QGraphicsScenePrivate::itemsAtPosition.

The old approach discovered a bug in QWidget::mapToGlobal in the context of
lighthouse, which in turn brought our eyes to
QGraphicsScenePrivate::itemsAtPosition. The implementation itself was
correct, but we can easily remove the-not-so-cheap mapToGlobal call
since we already have the scene position, which is all we need.

This functionality is heavily tested by existing auto tests, and all of
them pass.

Reviewed-by: mae

1 files changed, 3 insertions, 7 deletions

diff --git a/src/gui/graphicsview/qgraphicsscene.cpp b/src/gui/graphicsview/qgraphicsscene.cpp
index 3c23884..4fb754c 100644
--- a/src/gui/graphicsview/qgraphicsscene.cpp
+++ b/src/gui/graphicsview/qgraphicsscene.cpp
@@ -1074,7 +1074,7 @@ void QGraphicsScenePrivate::enableMouseTrackingOnViews()
 /*!
     Returns all items for the screen position in \a event.
 */
-QList<QGraphicsItem *> QGraphicsScenePrivate::itemsAtPosition(const QPoint &screenPos,
+QList<QGraphicsItem *> QGraphicsScenePrivate::itemsAtPosition(const QPoint &/*screenPos*/,
                                                               const QPointF &scenePos,
                                                               QWidget *widget) const
 {
@@ -1083,16 +1083,12 @@ QList<QGraphicsItem *> QGraphicsScenePrivate::itemsAtPosition(const QPoint &scre
     if (!view)
         return q->items(scenePos, Qt::IntersectsItemShape, Qt::DescendingOrder, QTransform());
 
-    const QRectF pointRect(QPointF(widget->mapFromGlobal(screenPos)), QSizeF(1, 1));
+    const QRectF pointRect(scenePos, QSizeF(1, 1));
     if (!view->isTransformed())
         return q->items(pointRect, Qt::IntersectsItemShape, Qt::DescendingOrder);
 
     const QTransform viewTransform = view->viewportTransform();
-    if (viewTransform.type() <= QTransform::TxScale) {
-        return q->items(viewTransform.inverted().mapRect(pointRect), Qt::IntersectsItemShape,
-                        Qt::DescendingOrder, viewTransform);
-    }
-    return q->items(viewTransform.inverted().map(pointRect), Qt::IntersectsItemShape,
+    return q->items(pointRect, Qt::IntersectsItemShape,
                     Qt::DescendingOrder, viewTransform);
 }