Safeguard QScreen::refreshRate against buggy platform behavior

Change-Id: I891bd5272db76e8562f6722b633cc0fdaac5f7a2
Task-number: QTBUG-43853
Reviewed-by: Robin Burchell <robin.burchell@viroteck.net>

2 files changed, 11 insertions, 3 deletions

diff --git a/src/gui/kernel/qguiapplication.cpp b/src/gui/kernel/qguiapplication.cpp
index dc5501eaf5..928d0cddc9 100644
--- a/src/gui/kernel/qguiapplication.cpp
+++ b/src/gui/kernel/qguiapplication.cpp
@@ -2578,9 +2578,14 @@ void QGuiApplicationPrivate::reportRefreshRateChange(QWindowSystemInterfacePriva
         return;
 
     QScreen *s = e->screen.data();
-    s->d_func()->refreshRate = e->rate;
-
-    emit s->refreshRateChanged(s->refreshRate());
+    qreal rate = e->rate;
+    // safeguard ourselves against buggy platform behavior...
+    if (rate < 1.0)
+        rate = 60.0;
+    if (!qFuzzyCompare(s->d_func()->refreshRate, rate)) {
+        s->d_func()->refreshRate = rate;
+        emit s->refreshRateChanged(s->refreshRate());
+    }
 }
 
 void QGuiApplicationPrivate::processExposeEvent(QWindowSystemInterfacePrivate::ExposeEvent *e)
diff --git a/src/gui/kernel/qscreen_p.h b/src/gui/kernel/qscreen_p.h
index cdb923c429..53d4f3404a 100644
--- a/src/gui/kernel/qscreen_p.h
+++ b/src/gui/kernel/qscreen_p.h
@@ -64,6 +64,9 @@ public:
         availableGeometry = platformScreen->availableGeometry();
         logicalDpi = platformScreen->logicalDpi();
         refreshRate = platformScreen->refreshRate();
+        // safeguard ourselves against buggy platform behavior...
+        if (refreshRate < 1.0)
+            refreshRate = 60.0;
 
         updatePrimaryOrientation();