1 files changed, 28 insertions, 23 deletions

diff --git a/src/gui/kernel/qhighdpiscaling.cpp b/src/gui/kernel/qhighdpiscaling.cpp
index 666a79463f..a0e1b48dcb 100644
--- a/src/gui/kernel/qhighdpiscaling.cpp
+++ b/src/gui/kernel/qhighdpiscaling.cpp
@@ -494,10 +494,11 @@ void QHighDpiScaling::updateHighDpiScaling()
         qCDebug(lcHighDpi) << "Applying screen factors" << m_screenFactors;
         int i = -1;
         const auto screens = QGuiApplication::screens();
-        for (const auto &[name, factor] : m_screenFactors) {
+        for (const auto &[name, rawFactor]: m_screenFactors) {
+            const qreal factor = roundScaleFactor(rawFactor);
             ++i;
             if (name.isNull()) {
-                if (i < screens.count())
+                if (i < screens.size())
                     setScreenFactor(screens.at(i), factor);
             } else {
                 for (QScreen *screen : screens) {
@@ -540,15 +541,17 @@ void QHighDpiScaling::setGlobalFactor(qreal factor)
     if (!QGuiApplication::allWindows().isEmpty())
         qWarning("QHighDpiScaling::setFactor: Should only be called when no windows exist.");
 
+    const auto screens = QGuiApplication::screens();
+
+    std::vector<QScreenPrivate::UpdateEmitter> updateEmitters;
+    for (QScreen *screen : screens)
+        updateEmitters.emplace_back(screen);
+
     m_globalScalingActive = !qFuzzyCompare(factor, qreal(1));
     m_factor = m_globalScalingActive ? factor : qreal(1);
     m_active = m_globalScalingActive || m_screenFactorSet || m_platformPluginDpiScalingActive ;
-    const auto screens = QGuiApplication::screens();
     for (QScreen *screen : screens)
         screen->d_func()->updateGeometry();
-
-    // FIXME: The geometry has been updated based on the new scale factor,
-    // but we don't emit any geometry change signals for the screens.
 }
 
 static const char scaleFactorProperty[] = "_q_scaleFactor";
@@ -565,6 +568,8 @@ void QHighDpiScaling::setScreenFactor(QScreen *screen, qreal factor)
         m_active = true;
     }
 
+    QScreenPrivate::UpdateEmitter updateEmitter(screen);
+
     // Prefer associating the factor with screen name over the object
     // since the screen object may be deleted on screen disconnects.
     const QString name = screen->name();
@@ -573,9 +578,7 @@ void QHighDpiScaling::setScreenFactor(QScreen *screen, qreal factor)
     else
         QHighDpiScaling::m_namedScreenScaleFactors.insert(name, factor);
 
-    // hack to force re-evaluation of screen geometry
-    if (screen->handle())
-        screen->d_func()->setPlatformScreen(screen->handle()); // updates geometries based on scale factor
+    screen->d_func()->updateGeometry();
 }
 
 QPoint QHighDpiScaling::mapPositionToNative(const QPoint &pos, const QPlatformScreen *platformScreen)
@@ -696,7 +699,7 @@ QVector<QHighDpiScaling::ScreenFactor> QHighDpiScaling::parseScreenScaleFactorsS
     // - a semicolon-separated name=factor list: "foo=1.5;bar=2;baz=3"
     const auto specs = screenScaleFactors.split(u';');
     for (const auto &spec : specs) {
-        const int equalsPos = spec.lastIndexOf(u'=');
+        const qsizetype equalsPos = spec.lastIndexOf(u'=');
         if (equalsPos == -1) {
             // screens in order
             bool ok;
@@ -750,7 +753,20 @@ QHighDpiScaling::ScaleAndOrigin QHighDpiScaling::scaleAndOrigin(const QWindow *w
     return scaleAndOrigin(targetScreen, position);
 }
 
-#else
+#ifndef QT_NO_DEBUG_STREAM
+QDebug operator<<(QDebug debug, const QHighDpiScaling::ScreenFactor &factor)
+{
+    const QDebugStateSaver saver(debug);
+    debug.nospace();
+    if (!factor.name.isEmpty())
+        debug << factor.name << "=";
+    debug << factor.factor;
+    return debug;
+}
+#endif
+
+#else // QT_NO_HIGHDPISCALING
+
 QHighDpiScaling::ScaleAndOrigin QHighDpiScaling::scaleAndOrigin(const QPlatformScreen *, QPoint *)
 {
     return { qreal(1), QPoint() };
@@ -765,19 +781,8 @@ QHighDpiScaling::ScaleAndOrigin QHighDpiScaling::scaleAndOrigin(const QWindow *,
 {
     return { qreal(1), QPoint() };
 }
-#endif //QT_NO_HIGHDPISCALING
 
-#ifndef QT_NO_DEBUG_STREAM
-QDebug operator<<(QDebug debug, const QHighDpiScaling::ScreenFactor &factor)
-{
-    const QDebugStateSaver saver(debug);
-    debug.nospace();
-    if (!factor.name.isEmpty())
-        debug << factor.name << "=";
-    debug << factor.factor;
-    return debug;
-}
-#endif
+#endif // QT_NO_HIGHDPISCALING
 
 QT_END_NAMESPACE