fix crash if no screens are available

Fixes: QTBUG-73166
Change-Id: I936672b7a09a540d21e6dcd371f5ffe1e5536b85
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

1 files changed, 6 insertions, 3 deletions

diff --git a/src/gui/kernel/qhighdpiscaling.cpp b/src/gui/kernel/qhighdpiscaling.cpp
index a455aa639d..22e46e0851 100644
--- a/src/gui/kernel/qhighdpiscaling.cpp
+++ b/src/gui/kernel/qhighdpiscaling.cpp
@@ -313,9 +313,12 @@ void QHighDpiScaling::updateHighDpiScaling()
     }
     m_active = m_globalScalingActive || m_screenFactorSet || m_pixelDensityScalingActive;
 
-    QPlatformScreen *primaryScreen = QGuiApplication::primaryScreen()->handle();
-    qreal sf = screenSubfactor(primaryScreen);
-    QDpi primaryDpi = primaryScreen->logicalDpi();
+    QScreen *primaryScreen = QGuiApplication::primaryScreen();
+    if (!primaryScreen)
+        return;
+    QPlatformScreen *platformScreen = primaryScreen->handle();
+    qreal sf = screenSubfactor(platformScreen);
+    QDpi primaryDpi = platformScreen->logicalDpi();
     m_logicalDpi = QDpi(primaryDpi.first / sf, primaryDpi.second / sf);
 }