Add accessors for QWindow and QScreen to QWidgetPrivate

Rewrite the existing accessor QWidgetPrivate::windowHandle() to
accept a mode enumeration that has an "Any" convenience.

Based on that, add QWidgetPrivate::associatedScreen(), which is seful
in many places where scaling is performed.

Prototypically simplify the code.

Task-number: QTBUG-62094
Task-number: QTBUG-73231
Change-Id: I516288363d329bce9bc94e4951106f9357bc6cde
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

src/widgets/accessible/qaccessiblemenu.cpp

@@ -47,6 +47,7 @@
 #endif
 #include <QtWidgets/QAction>
 #include <qstyle.h>
+#include <private/qwidget_p.h>
 
 #ifndef QT_NO_ACCESSIBILITY
 
@@ -241,15 +242,9 @@ QObject *QAccessibleMenuItem::object() const
 /*! \reimp */
 QWindow *QAccessibleMenuItem::window() const
 {
-    QWindow *result = nullptr;
-    if (!m_owner.isNull()) {
-        result = m_owner->windowHandle();
-        if (!result) {
-            if (const QWidget *nativeParent = m_owner->nativeParentWidget())
-                result = nativeParent->windowHandle();
-        }
-    }
-    return result;
+    return m_owner.isNull()
+        ? nullptr
+        : qt_widget_private(m_owner.data())->windowHandle(QWidgetPrivate::WindowHandleMode::Closest);
 }
 
 QRect QAccessibleMenuItem::rect() const

src/widgets/dialogs/qmessagebox.cpp

@@ -2662,14 +2662,9 @@ QPixmap QMessageBoxPrivate::standardIcon(QMessageBox::Icon icon, QMessageBox *mb
         break;
     }
     if (!tmpIcon.isNull()) {
-        QWindow *window = nullptr;
-        if (mb) {
-            window = mb->windowHandle();
-            if (!window) {
-                if (const QWidget *nativeParent = mb->nativeParentWidget())
-                    window = nativeParent->windowHandle();
-            }
-        }
+        QWindow *window = mb
+            ? qt_widget_private(mb)->windowHandle(QWidgetPrivate::WindowHandleMode::Closest)
+            : nullptr;
         return tmpIcon.pixmap(window, QSize(iconSize, iconSize));
     }
     return QPixmap();

src/widgets/itemviews/qabstractitemview.cpp

@@ -4461,15 +4461,8 @@ QPixmap QAbstractItemViewPrivate::renderToPixmap(const QModelIndexList &indexes,
     if (paintPairs.isEmpty())
         return QPixmap();
 
-    qreal scale = 1.0f;
-
-    Q_Q(const QAbstractItemView);
-    QWidget *window = q->window();
-    if (window) {
-        QWindow *windowHandle = window->windowHandle();
-        if (windowHandle)
-            scale = windowHandle->devicePixelRatio();
-    }
+    QWindow *window = windowHandle(WindowHandleMode::Closest);
+    const qreal scale = window ? window->devicePixelRatio() : qreal(1);
 
     QPixmap pixmap(r->size() * scale);
     pixmap.setDevicePixelRatio(scale);

src/widgets/kernel/qdesktopwidget.cpp

@@ -321,20 +321,12 @@ int QDesktopWidgetPrivate::screenNumber(const QWidget *w)
     if (screens.isEmpty()) // This should never happen
         return primaryScreen();
 
-    const QWindow *winHandle = w->windowHandle();
-    if (!winHandle) {
-        if (const QWidget *nativeParent = w->nativeParentWidget())
-            winHandle = nativeParent->windowHandle();
-    }
-
     // If there is more than one virtual desktop
     if (screens.count() != screens.constFirst()->virtualSiblings().count()) {
         // Find the root widget, get a QScreen from it and use the
         // virtual siblings for checking the window position.
-        if (winHandle) {
-            if (const QScreen *winScreen = winHandle->screen())
-                screens = winScreen->virtualSiblings();
-        }
+        if (const QScreen *winScreen = qt_widget_private(const_cast<QWidget *>(w))->associatedScreen())
+            screens = winScreen->virtualSiblings();
     }
 
     // Get the screen number from window position using screen geometry

src/widgets/kernel/qopenglwidget.cpp

@@ -1333,11 +1333,8 @@ int QOpenGLWidget::metric(QPaintDevice::PaintDeviceMetric metric) const
     if (d->inBackingStorePaint)
         return QWidget::metric(metric);
 
-    QWidget *tlw = window();
-    QWindow *window = tlw ? tlw->windowHandle() : 0;
-    QScreen *screen = tlw && tlw->windowHandle() ? tlw->windowHandle()->screen() : 0;
-    if (!screen && QGuiApplication::primaryScreen())
-        screen = QGuiApplication::primaryScreen();
+    auto window = d->windowHandle(QWidgetPrivate::WindowHandleMode::TopLevel);
+    QScreen *screen = window ? window->screen() : QGuiApplication::primaryScreen();
 
     const float dpmx = qt_defaultDpiX() * 100. / 2.54;
     const float dpmy = qt_defaultDpiY() * 100. / 2.54;

src/widgets/kernel/qwidget.cpp

@@ -1252,6 +1252,33 @@ void QWidgetPrivate::createRecursively()
     }
 }
 
+QWindow *QWidgetPrivate::windowHandle(WindowHandleMode mode) const
+{
+    if (mode == WindowHandleMode::Direct || mode == WindowHandleMode::Closest) {
+        if (QTLWExtra *x = maybeTopData())
+            return x->window;
+    }
+    if (mode == WindowHandleMode::Closest) {
+        if (auto nativeParent = q_func()->nativeParentWidget()) {
+            if (auto window = nativeParent->windowHandle())
+                return window;
+        }
+    }
+    if (mode == WindowHandleMode::TopLevel || mode == WindowHandleMode::Closest) {
+        if (auto topLevel = q_func()->topLevelWidget()) {
+            if (auto window = topLevel ->windowHandle())
+                return window;
+        }
+    }
+    return nullptr;
+}
+
+QScreen *QWidgetPrivate::associatedScreen() const
+{
+    if (auto window = windowHandle(WindowHandleMode::Closest))
+        return window->screen();
+    return nullptr;
+}
 
 // ### fixme: Qt 6: Remove parameter window from QWidget::create()
 
@@ -8103,7 +8130,7 @@ void QWidgetPrivate::show_sys()
 {
     Q_Q(QWidget);
 
-    QWidgetWindow *window = windowHandle();
+    auto window = qobject_cast<QWidgetWindow *>(windowHandle());
 
     if (q->testAttribute(Qt::WA_DontShowOnScreen)) {
         invalidateBackingStore(q->rect());
@@ -8242,7 +8269,7 @@ void QWidgetPrivate::hide_sys()
 {
     Q_Q(QWidget);
 
-    QWidgetWindow *window = windowHandle();
+    auto window = qobject_cast<QWidgetWindow *>(windowHandle());
 
     if (q->testAttribute(Qt::WA_DontShowOnScreen)) {
         q->setAttribute(Qt::WA_Mapped, false);

src/widgets/kernel/qwidget_p.h

@@ -342,7 +342,15 @@ public:
     QPainter *sharedPainter() const;
     void setSharedPainter(QPainter *painter);
     QWidgetBackingStore *maybeBackingStore() const;
-    QWidgetWindow *windowHandle() const;
+
+    enum class WindowHandleMode {
+        Direct,
+        Closest,
+        TopLevel
+    };
+    QWindow *windowHandle(WindowHandleMode mode = WindowHandleMode::Direct) const;
+
+    QScreen *associatedScreen() const;
 
     template <typename T>
     void repaint(T t);
@@ -1014,13 +1022,6 @@ inline QWidgetBackingStore *QWidgetPrivate::maybeBackingStore() const
     return x ? x->backingStoreTracker.data() : nullptr;
 }
 
-inline QWidgetWindow *QWidgetPrivate::windowHandle() const
-{
-    if (QTLWExtra *x = maybeTopData())
-        return x->window;
-    return nullptr;
-}
-
 QT_END_NAMESPACE
 
 #endif // QWIDGET_P_H

src/widgets/kernel/qwidgetwindow.cpp

@@ -592,10 +592,7 @@ void QWidgetWindow::handleMouseEvent(QMouseEvent *event)
                         w->window()->raise();
                     }
 
-                    QWindow *win = w->windowHandle();
-                    if (!win)
-                        win = w->nativeParentWidget()->windowHandle();
-                    if (win) {
+                    if (auto win = qt_widget_private(w)->windowHandle(QWidgetPrivate::WindowHandleMode::Closest)) {
                         const QRect globalGeometry = win->isTopLevel()
                             ? win->geometry()
                             : QRect(win->mapToGlobal(QPoint(0, 0)), win->size());

src/widgets/styles/qwindowsstyle.cpp

@@ -380,23 +380,12 @@ int QWindowsStylePrivate::fixedPixelMetric(QStyle::PixelMetric pm)
     return QWindowsStylePrivate::InvalidMetric;
 }
 
-static QWindow *windowOf(const QWidget *w)
-{
-    QWindow *result = nullptr;
-    if (w) {
-        result = w->windowHandle();
-        if (!result) {
-            if (const QWidget *np = w->nativeParentWidget())
-                result = np->windowHandle();
-        }
-    }
-    return result;
-}
-
 static QScreen *screenOf(const QWidget *w)
 {
-    if (const QWindow *window = windowOf(w))
-        return window->screen();
+    if (w) {
+        if (auto screen = qt_widget_private(const_cast<QWidget *>(w))->associatedScreen())
+            return screen;
+    }
     return QGuiApplication::primaryScreen();
 }
 

src/widgets/widgets/qcombobox.cpp

@@ -2838,19 +2838,15 @@ void QComboBox::showPopup()
     bool startTimer = !container->isVisible();
     container->raise();
     container->create();
-    QWindow *containerWindow = container->window()->windowHandle();
-    if (containerWindow) {
-        QWindow *win = window()->windowHandle();
-        if (win) {
-            QScreen *currentScreen = win->screen();
-            if (currentScreen && !currentScreen->virtualSiblings().contains(containerWindow->screen())) {
-                containerWindow->setScreen(currentScreen);
+    if (QWindow *containerWindow = qt_widget_private(container)->windowHandle(QWidgetPrivate::WindowHandleMode::TopLevel)) {
+        QScreen *currentScreen = d->associatedScreen();
+        if (currentScreen && !currentScreen->virtualSiblings().contains(containerWindow->screen())) {
+            containerWindow->setScreen(currentScreen);
 
-                // This seems to workaround an issue in xcb+multi GPU+multiscreen
-                // environment where the window might not always show up when screen
-                // is changed.
-                container->hide();
-            }
+            // This seems to workaround an issue in xcb+multi GPU+multiscreen
+            // environment where the window might not always show up when screen
+            // is changed.
+            container->hide();
         }
     }
     container->show();

src/widgets/widgets/qdockwidget.cpp

@@ -1535,10 +1535,10 @@ bool QDockWidget::event(QEvent *event)
         d->toggleViewAction->setChecked(true);
         QPoint parentTopLeft(0, 0);
         if (isWindow()) {
-            if (const QWindow *window = windowHandle())
-                parentTopLeft = window->screen()->availableVirtualGeometry().topLeft();
-            else
-                parentTopLeft = QGuiApplication::primaryScreen()->availableVirtualGeometry().topLeft();
+            const QScreen *screen = d->associatedScreen();
+            parentTopLeft = screen
+                ? screen->availableVirtualGeometry().topLeft()
+                : QGuiApplication::primaryScreen()->availableVirtualGeometry().topLeft();
         }
         emit visibilityChanged(geometry().right() >= parentTopLeft.x() && geometry().bottom() >= parentTopLeft.y());
 }

src/widgets/widgets/qlineedit_p.cpp

@@ -355,9 +355,7 @@ QLineEditPrivate *QLineEditIconButton::lineEditPrivate() const
 void QLineEditIconButton::paintEvent(QPaintEvent *)
 {
     QPainter painter(this);
-    QWindow *window = nullptr;
-    if (const QWidget *nativeParent = nativeParentWidget())
-        window = nativeParent->windowHandle();
+    QWindow *window = qt_widget_private(this)->windowHandle(QWidgetPrivate::WindowHandleMode::Closest);
     QIcon::Mode state = QIcon::Disabled;
     if (isEnabled())
         state = isDown() ? QIcon::Active : QIcon::Normal;

src/widgets/widgets/qmainwindowlayout.cpp

@@ -2584,9 +2584,9 @@ void QMainWindowLayout::hover(QLayoutItem *widgetItem, const QPoint &mousePos)
             }
         }
         for (QWidget *w : candidates) {
-            QWindow *handle1 = widget->windowHandle();
-            QWindow *handle2 = w->windowHandle();
-            if (handle1 && handle2 && handle1->screen() != handle2->screen())
+            const QScreen *screen1 = qt_widget_private(widget)->associatedScreen();
+            const QScreen *screen2 = qt_widget_private(w)->associatedScreen();
+            if (screen1 && screen2 && screen1 != screen2)
                 continue;
             if (!w->geometry().contains(mousePos))
                 continue;