[layouts] Move responsibility for matching map colors to project

background color to app

This fits better in app - the silent auto setting of background
colors should not apply to scripts manually creating QgsLayoutItemMap
items.

Author: nyalldawson

src/app/layout/qgslayoutapputils.cpp

@@ -78,6 +78,13 @@ void QgsLayoutAppUtils::registerGuiForKnownItemTypes()
   {
     QgsLayoutItemMap *map = qobject_cast< QgsLayoutItemMap * >( item );
     Q_ASSERT( map );
+
+    //get the color for map canvas background and set map background color accordingly
+    int bgRedInt = QgsProject::instance()->readNumEntry( QStringLiteral( "Gui" ), QStringLiteral( "/CanvasColorRedPart" ), 255 );
+    int bgGreenInt = QgsProject::instance()->readNumEntry( QStringLiteral( "Gui" ), QStringLiteral( "/CanvasColorGreenPart" ), 255 );
+    int bgBlueInt = QgsProject::instance()->readNumEntry( QStringLiteral( "Gui" ), QStringLiteral( "/CanvasColorBluePart" ), 255 );
+    map->setBackgroundColor( QColor( bgRedInt, bgGreenInt, bgBlueInt ) );
+
     if ( QgisApp::instance()->mapCanvas() )
     {
       map->zoomToExtent( QgisApp::instance()->mapCanvas()->mapSettings().visibleExtent() );

src/core/layout/qgslayoutitemmap.cpp

@@ -40,18 +40,6 @@ QgsLayoutItemMap::QgsLayoutItemMap( QgsLayout *layout )
 
   assignFreeId();
 
-  if ( layout )
-  {
-    if ( QgsProject *project = layout->project() )
-    {
-      //get the color for map canvas background and set map background color accordingly
-      int bgRedInt = project->readNumEntry( QStringLiteral( "Gui" ), QStringLiteral( "/CanvasColorRedPart" ), 255 );
-      int bgGreenInt = project->readNumEntry( QStringLiteral( "Gui" ), QStringLiteral( "/CanvasColorGreenPart" ), 255 );
-      int bgBlueInt = project->readNumEntry( QStringLiteral( "Gui" ), QStringLiteral( "/CanvasColorBluePart" ), 255 );
-      setBackgroundColor( QColor( bgRedInt, bgGreenInt, bgBlueInt ) );
-    }
-  }
-
   connect( this, &QgsLayoutItem::sizePositionChanged, this, [ = ]
   {
     shapeChanged();