QMenu: Fix size on high DPI + multi screen

When calculating item sizes (used for menu size) the styles consider the widget screen. This widget screen could be a wrong default or an obsolete value. This patch ensures the screen is correct set on popup. [ChangeLog][QtWidgets][QMenu] Fixed menu size issue when using high DPI on multi-screen system. Task-number: QTBUG-59794 Change-Id: I84461441d5d33cb8dc04ab1acb9630fbfc8c5514 Reviewed-by: Friedemann Kleint <[email protected]> Reviewed-by: Morten Kristensen <[email protected]> Reviewed-by: Per Liboriussen <[email protected]> Reviewed-by: Gabriel de Dietrich <[email protected]>
RDevCore · Sep 13, 2017 · 9ad0e09 · 9ad0e09
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diff --git a/src/widgets/widgets/qmenu.cpp b/src/widgets/widgets/qmenu.cpp
@@ -849,6 +849,24 @@ void QMenuPrivate::_q_overrideMenuActionDestroyed()
     menuAction=defaultMenuAction;
 }
 
+void QMenuPrivate::adjustMenuScreen(const QPoint &p)
+{
+    Q_Q(QMenu);
+    // The windowHandle must point to the screen where the menu will be shown.
+    // The (item) size calculations depend on the menu screen,
+    // so a wrong screen would often cause wrong sizes (on high DPI)
+    const QScreen *primaryScreen = QApplication::primaryScreen();
+    const QScreen *currentScreen = q->windowHandle() ? q->windowHandle()->screen() : primaryScreen;
+    const int screenNumberForPoint = QApplication::desktop()->screenNumber(p);
+    QScreen *actualScreen = QGuiApplication::screens().at(screenNumberForPoint);
+    if (actualScreen && currentScreen != actualScreen) {
+        if (!q->windowHandle()) // Try to create a window handle if not created.
+            createWinId();
+        if (q->windowHandle())
+            q->windowHandle()->setScreen(actualScreen);
+        itemsDirty = true;
+    }
+}
 
 void QMenuPrivate::updateLayoutDirection()
 {
@@ -2313,6 +2331,7 @@ void QMenu::popup(const QPoint &p, QAction *atAction)
     d->motions = 0;
     d->doChildEffects = true;
     d->updateLayoutDirection();
+    d->adjustMenuScreen(p);
 
 #if QT_CONFIG(menubar)
     // if this menu is part of a chain attached to a QMenuBar, set the

diff --git a/src/widgets/widgets/qmenu_p.h b/src/widgets/widgets/qmenu_p.h
@@ -447,6 +447,7 @@ class QMenuPrivate : public QWidgetPrivate
 
     bool hasMouseMoved(const QPoint &globalPos);
 
+    void adjustMenuScreen(const QPoint &p);
     void updateLayoutDirection();
 
     //menu fading/scrolling effects