From a8ecc683b72a3842a480e3e562456cbec8bad667 Mon Sep 17 00:00:00 2001
From: Nyall Dawson <nyall.dawson@gmail.com>
Date: Mon, 19 Nov 2018 14:43:58 +1000
Subject: [PATCH] Avoid QObject::connect null warning

---
 src/gui/qgsmapcanvas.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/gui/qgsmapcanvas.cpp b/src/gui/qgsmapcanvas.cpp
index eb6a95fd9cd..1075331039e 100644
--- a/src/gui/qgsmapcanvas.cpp
+++ b/src/gui/qgsmapcanvas.cpp
@@ -172,9 +172,11 @@ QgsMapCanvas::QgsMapCanvas( QWidget *parent )
   moveCanvasContents( true );
 
   // keep device pixel ratio up to date on screen or resolution change
-  connect( window()->windowHandle(), &QWindow::screenChanged, this, [ = ]( QScreen * ) {mSettings.setDevicePixelRatio( devicePixelRatio() );} );
   if ( window()->windowHandle() )
+  {
+    connect( window()->windowHandle(), &QWindow::screenChanged, this, [ = ]( QScreen * ) {mSettings.setDevicePixelRatio( devicePixelRatio() );} );
     connect( window()->windowHandle()->screen(), &QScreen::physicalDotsPerInchChanged, this, [ = ]( qreal ) {mSettings.setDevicePixelRatio( devicePixelRatio() );} );
+  }
 
   connect( &mMapUpdateTimer, &QTimer::timeout, this, &QgsMapCanvas::mapUpdateTimeout );
   mMapUpdateTimer.setInterval( 250 );