Add QScreen::virtualSiblingAt() and use it in QMenubarPrivate::popupAction

QGuiApplication::screenAt() is documented "If the point maps to more
than one set of virtual siblings, the first match is returned."
But in many cases it's possible to start from a known screen and
consider only its siblings, as when deciding where to open a QMenu
from a QMenuBar: the QMenuBar is already shown on some screen(s),
so the QMenu must be shown on a sibling from that set.  This function
should be useful in other such cases too, hence it might as well
be public API.

Task-number: QTBUG-76162
Change-Id: I83c74b40eb53f56fb285a6074a3dc2c0ea9c570b
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

1 files changed, 4 insertions, 9 deletions

diff --git a/src/widgets/widgets/qmenubar.cpp b/src/widgets/widgets/qmenubar.cpp
index 3d31a3b73a..69b1c5896f 100644
--- a/src/widgets/widgets/qmenubar.cpp
+++ b/src/widgets/widgets/qmenubar.cpp
@@ -324,15 +324,10 @@ void QMenuBarPrivate::popupAction(QAction *action, bool activateFirst)
         QPoint pos(q->mapToGlobal(QPoint(adjustedActionRect.left(), adjustedActionRect.bottom() + 1)));
         QSize popup_size = activeMenu->sizeHint();
         //we put the popup menu on the screen containing the bottom-center of the action rect
-        QScreen *popupScreen = q->window()->windowHandle()->screen();
-        QPoint bottomMiddlePos = pos + QPoint(adjustedActionRect.width() / 2, 0);
-        const auto &siblings = popupScreen->virtualSiblings();
-        for (QScreen *sibling : siblings) {
-            if (sibling->geometry().contains(bottomMiddlePos)) {
-                popupScreen = sibling;
-                break;
-            }
-        }
+        QScreen *menubarScreen = q->window()->windowHandle()->screen();
+        QScreen *popupScreen = menubarScreen->virtualSiblingAt(pos + QPoint(adjustedActionRect.width() / 2, 0));
+        if (!popupScreen)
+            popupScreen = menubarScreen;
         QRect screenRect = popupScreen->geometry();
         pos = QPoint(qMax(pos.x(), screenRect.x()), qMax(pos.y(), screenRect.y()));
         const bool fitUp = (pos.y() - popup_size.height() >= screenRect.top());