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>

3 files changed, 23 insertions, 1 deletions

diff --git a/src/gui/kernel/qguiapplication.cpp b/src/gui/kernel/qguiapplication.cpp
index a3ef3b2314..c21bc90d39 100644
--- a/src/gui/kernel/qguiapplication.cpp
+++ b/src/gui/kernel/qguiapplication.cpp
@@ -1040,7 +1040,9 @@ QList<QScreen *> QGuiApplication::screens()
 
     The \a point is in relation to the virtualGeometry() of each set of virtual
     siblings. If the point maps to more than one set of virtual siblings the first
-    match is returned.
+    match is returned.  If you wish to search only the virtual desktop siblings
+    of a known screen (for example siblings of the screen of your application
+    window \c QWidget::windowHandle()->screen()), use QScreen::virtualSiblingAt().
 
     \since 5.10
 */
diff --git a/src/gui/kernel/qscreen.cpp b/src/gui/kernel/qscreen.cpp
index 7adf3db1b8..80de561297 100644
--- a/src/gui/kernel/qscreen.cpp
+++ b/src/gui/kernel/qscreen.cpp
@@ -700,6 +700,25 @@ void QScreenPrivate::updatePrimaryOrientation()
 }
 
 /*!
+    Returns the screen at \a point within the set of \l QScreen::virtualSiblings(),
+    or \c nullptr if outside of any screen.
+
+    The \a point is in relation to the virtualGeometry() of each set of virtual
+    siblings.
+
+    \since 5.15
+*/
+QScreen *QScreen::virtualSiblingAt(const QPoint &point)
+{
+    const auto &siblings = virtualSiblings();
+    for (QScreen *sibling : siblings) {
+        if (sibling->geometry().contains(point))
+            return sibling;
+    }
+    return nullptr;
+}
+
+/*!
     Creates and returns a pixmap constructed by grabbing the contents
     of the given \a window restricted by QRect(\a x, \a y, \a width,
     \a height).
diff --git a/src/gui/kernel/qscreen.h b/src/gui/kernel/qscreen.h
index 14392d3036..88925ab731 100644
--- a/src/gui/kernel/qscreen.h
+++ b/src/gui/kernel/qscreen.h
@@ -125,6 +125,7 @@ public:
     QRect availableGeometry() const;
 
     QList<QScreen *> virtualSiblings() const;
+    QScreen *virtualSiblingAt(const QPoint &point);
 
     QSize virtualSize() const;
     QRect virtualGeometry() const;