Avoid QRubberBand leaving artefacts in QListView

On hidpi screens, the painted edges of the rubberband can extend
beyond the selection rect because of scaling. Extend the area to be
updated by 2x frame width, when the rubberband changes.

Fixes: QTBUG-113432
Pick-to: 6.5
Change-Id: Ie7aec1fefdc3fbf71c63952b693f462697adf849
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
(cherry picked from commit a5a6b657a799cbed4567f60342714df52f9c8891)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit bcc581761451b4464d5a81f83d8d2afb07ca9512)

1 files changed, 7 insertions, 2 deletions

diff --git a/src/widgets/itemviews/qlistview.cpp b/src/widgets/itemviews/qlistview.cpp
index bfa28c6e51..3a526d0878 100644
--- a/src/widgets/itemviews/qlistview.cpp
+++ b/src/widgets/itemviews/qlistview.cpp
@@ -755,7 +755,10 @@ void QListView::mouseMoveEvent(QMouseEvent *e)
         && d->selectionMode != NoSelection) {
         QRect rect(d->pressedPosition, e->position().toPoint() + QPoint(horizontalOffset(), verticalOffset()));
         rect = rect.normalized();
-        d->viewport->update(d->mapToViewport(rect.united(d->elasticBand)));
+        const int margin = 2 * style()->pixelMetric(QStyle::PM_DefaultFrameWidth);
+        const QRect viewPortRect = rect.united(d->elasticBand)
+                                       .adjusted(-margin, -margin, margin, margin);
+        d->viewport->update(d->mapToViewport(viewPortRect));
         d->elasticBand = rect;
     }
 }
@@ -769,7 +772,9 @@ void QListView::mouseReleaseEvent(QMouseEvent *e)
     QAbstractItemView::mouseReleaseEvent(e);
     // #### move this implementation into a dynamic class
     if (d->showElasticBand && d->elasticBand.isValid()) {
-        d->viewport->update(d->mapToViewport(d->elasticBand));
+        const int margin = 2 * style()->pixelMetric(QStyle::PM_DefaultFrameWidth);
+        const QRect viewPortRect = d->elasticBand.adjusted(-margin, -margin, margin, margin);
+        d->viewport->update(d->mapToViewport(viewPortRect));
         d->elasticBand = QRect();
     }
 }