Strip non-spatial and nullptrs from list when calling

QgsMapSettings::setLayers

Since neither can be rendered, we filter them from the list
of layers to be rendered in the map.

(cherry-picked from 5b8599e)

python/core/qgsmapsettings.sip.in

@@ -124,6 +124,10 @@ The layers are stored in the reverse order of how they are rendered (layer with
 %Docstring
 Set list of layers for map rendering. The layers must be registered in :py:class:`QgsProject`.
 The layers are stored in the reverse order of how they are rendered (layer with index 0 will be on top)
+
+.. note::
+
+   Any non-spatial layers will be automatically stripped from the list (since they cannot be rendered!).
 %End
 
     QMap<QString, QString> layerStyleOverrides() const;

src/core/qgsmapsettings.cpp

@@ -256,7 +256,15 @@ QList<QgsMapLayer *> QgsMapSettings::layers() const
 
 void QgsMapSettings::setLayers( const QList<QgsMapLayer *> &layers )
 {
-  mLayers = _qgis_listRawToQPointer( layers );
+  // filter list, removing null layers and non-spatial layers
+  auto filteredList = layers;
+  filteredList.erase( std::remove_if( filteredList.begin(), filteredList.end(),
+                                      []( QgsMapLayer * layer )
+  {
+    return !layer || !layer->isSpatial();
+  } ), filteredList.end() );
+
+  mLayers = _qgis_listRawToQPointer( filteredList );
 }
 
 QMap<QString, QString> QgsMapSettings::layerStyleOverrides() const

src/core/qgsmapsettings.h

@@ -133,6 +133,8 @@ class CORE_EXPORT QgsMapSettings
     /**
      * Set list of layers for map rendering. The layers must be registered in QgsProject.
      * The layers are stored in the reverse order of how they are rendered (layer with index 0 will be on top)
+     *
+     * \note Any non-spatial layers will be automatically stripped from the list (since they cannot be rendered!).
      */
     void setLayers( const QList<QgsMapLayer *> &layers );
 

tests/src/core/testqgsmapsettings.cpp

@@ -41,6 +41,7 @@ class TestQgsMapSettings: public QObject
     void testIsLayerVisible();
     void testMapLayerListUtils();
     void testXmlReadWrite();
+    void testSetLayers();
 
   private:
     QString toString( const QPolygonF &p, int decimalPlaces = 2 ) const;
@@ -281,5 +282,22 @@ void TestQgsMapSettings::testXmlReadWrite()
   QVERIFY( !s2.destinationCrs().isValid() );
 }
 
+void TestQgsMapSettings::testSetLayers()
+{
+  std::unique_ptr<  QgsVectorLayer  > vlA = qgis::make_unique< QgsVectorLayer >( QStringLiteral( "Point" ), QStringLiteral( "a" ), QStringLiteral( "memory" ) );
+  std::unique_ptr<  QgsVectorLayer  > vlB = qgis::make_unique< QgsVectorLayer >( QStringLiteral( "Point" ), QStringLiteral( "b" ), QStringLiteral( "memory" ) );
+  std::unique_ptr<  QgsVectorLayer  > nonSpatial = qgis::make_unique< QgsVectorLayer >( QStringLiteral( "none" ), QStringLiteral( "a" ), QStringLiteral( "memory" ) );
+
+  QgsMapSettings ms;
+  ms.setLayers( QList< QgsMapLayer * >() << vlA.get() );
+  QCOMPARE( ms.layers(), QList< QgsMapLayer * >() << vlA.get() );
+  ms.setLayers( QList< QgsMapLayer * >() << vlB.get() << vlA.get() );
+  QCOMPARE( ms.layers(), QList< QgsMapLayer * >() << vlB.get() << vlA.get() );
+
+  // non spatial and null layers should be stripped
+  ms.setLayers( QList< QgsMapLayer * >() << vlA.get() << nonSpatial.get() << nullptr << vlB.get() );
+  QCOMPARE( ms.layers(), QList< QgsMapLayer * >() << vlA.get() << vlB.get() );
+}
+
 QGSTEST_MAIN( TestQgsMapSettings )
 #include "testqgsmapsettings.moc"