physical dpi is only available after showEvent

m-kuhn · m-kuhn · commit 598e2bd31f53 · 2021-07-13T21:15:33.000+02:00
diff --git a/python/gui/auto_generated/qgsmapcanvas.sip.in b/python/gui/auto_generated/qgsmapcanvas.sip.in
@@ -1314,6 +1314,8 @@ called when panning is in action, reset indicates end of panning
     virtual void dropEvent( QDropEvent *event );
 
 
+    virtual void showEvent( QShowEvent *event );
+
 
 
 
diff --git a/src/gui/qgsmapcanvas.cpp b/src/gui/qgsmapcanvas.cpp
@@ -206,26 +206,12 @@ QgsMapCanvas::QgsMapCanvas( QWidget *parent )
 
   QSize s = viewport()->size();
   mSettings.setOutputSize( s );
-  updateDevicePixelFromScreen();
+
   setSceneRect( 0, 0, s.width(), s.height() );
   mScene->setSceneRect( QRectF( 0, 0, s.width(), s.height() ) );
 
   moveCanvasContents( true );
 
-
-  // keep device pixel ratio up to date on screen or resolution change
-  if ( window()->windowHandle() )
-  {
-    connect( window()->windowHandle(), &QWindow::screenChanged, this, [ = ]( QScreen * )
-    {
-      disconnect( mScreenDpiChangedConnection );
-      mScreenDpiChangedConnection = connect( window()->windowHandle()->screen(), &QScreen::physicalDotsPerInchChanged, this, &QgsMapCanvas::updateDevicePixelFromScreen );
-      updateDevicePixelFromScreen();
-    } );
-
-    mScreenDpiChangedConnection = connect( window()->windowHandle()->screen(), &QScreen::physicalDotsPerInchChanged, this, &QgsMapCanvas::updateDevicePixelFromScreen );
-  }
-
   connect( &mMapUpdateTimer, &QTimer::timeout, this, &QgsMapCanvas::mapUpdateTimeout );
   mMapUpdateTimer.setInterval( 250 );
 
@@ -2592,6 +2578,24 @@ void QgsMapCanvas::dropEvent( QDropEvent *event )
   }
 }
 
+void QgsMapCanvas::showEvent( QShowEvent *event )
+{
+  Q_UNUSED( event )
+  updateDevicePixelFromScreen();
+  // keep device pixel ratio up to date on screen or resolution change
+  if ( window()->windowHandle() )
+  {
+    connect( window()->windowHandle(), &QWindow::screenChanged, this, [ = ]( QScreen * )
+    {
+      disconnect( mScreenDpiChangedConnection );
+      mScreenDpiChangedConnection = connect( window()->windowHandle()->screen(), &QScreen::physicalDotsPerInchChanged, this, &QgsMapCanvas::updateDevicePixelFromScreen );
+      updateDevicePixelFromScreen();
+    } );
+
+    mScreenDpiChangedConnection = connect( window()->windowHandle()->screen(), &QScreen::physicalDotsPerInchChanged, this, &QgsMapCanvas::updateDevicePixelFromScreen );
+  }
+}
+
 QPoint QgsMapCanvas::mouseLastXY()
 {
   return mCanvasProperties->mouseLastXY;
diff --git a/src/gui/qgsmapcanvas.h b/src/gui/qgsmapcanvas.h
@@ -1183,6 +1183,7 @@ class GUI_EXPORT QgsMapCanvas : public QGraphicsView, public QgsExpressionContex
 
     void dropEvent( QDropEvent *event ) override;
 
+    void showEvent( QShowEvent *event ) override;
 
     /// implementation struct
     class CanvasProperties;

Original file line number	Diff line number	Diff line change
`@@ -1314,6 +1314,8 @@ called when panning is in action, reset indicates end of panning`
`1314`	`1314`	`virtual void dropEvent( QDropEvent *event );`
`1315`	`1315`
`1316`	`1316`
	`1317`	`+ virtual void showEvent( QShowEvent *event );`
	`1318`	`+`
`1317`	`1319`
`1318`	`1320`
`1319`	`1321`