[FEATURE] map_layers variable for layout map items

Just like map_layers_ids, but returns direct layer values instead
of ids

Author: nyalldawson

src/core/layout/qgslayoutitemmap.cpp

@@ -1155,18 +1155,27 @@ QgsExpressionContext QgsLayoutItemMap::createExpressionContext() const
   scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "map_crs_definition" ), mapCrs.toProj4(), true ) );
   scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "map_units" ), QgsUnitTypes::toString( mapCrs.mapUnits() ), true ) );
 
-  QVariantList layers_ids;
-  scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "map_layers_ids" ), layers_ids, true ) );
+  QVariantList layersIds;
+  QVariantList layers;
+  scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "map_layers_ids" ), layersIds, true ) );
+  scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "map_layers" ), layers, true ) );
 
   context.appendScope( scope );
 
-  // The scope map_layers_ids has been added to the context, only now we can call layersToRender
+  // The scope map_layers_ids and map_layers variables have been added to the context, only now we can
+  // call layersToRender (just in case layersToRender relies on evaluating an expression which uses
+  // other variables contained within the map settings scope
   const QList<QgsMapLayer *> layersInMap = layersToRender( &context );
+
+  layersIds.reserve( layersInMap.count() );
+  layers.reserve( layersInMap.count() );
   for ( QgsMapLayer *layer : layersInMap )
   {
-    layers_ids << layer->id();
+    layersIds << layer->id();
+    layers << QVariant::fromValue<QgsWeakMapLayerPointer>( QgsWeakMapLayerPointer( layer ) );
   }
-  scope->setVariable( QStringLiteral( "map_layers_ids" ), layers_ids );
+  scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "map_layers_ids" ), layersIds, true ) );
+  scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "map_layers" ), layers, true ) );
 
   return context;
 }

src/core/qgsexpressioncontext.cpp

@@ -995,13 +995,18 @@ QgsExpressionContextScope *QgsExpressionContextUtils::mapSettingsScope( const Qg
   scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "map_crs_definition" ), mapSettings.destinationCrs().toProj4(), true ) );
   scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "map_units" ), QgsUnitTypes::toString( mapSettings.mapUnits() ), true ) );
 
-  QVariantList layers_ids;
+  QVariantList layersIds;
+  QVariantList layers;
   const QList<QgsMapLayer *> layersInMap = mapSettings.layers();
+  layersIds.reserve( layersInMap.count() );
+  layers.reserve( layersInMap.count() );
   for ( QgsMapLayer *layer : layersInMap )
   {
-    layers_ids << layer->id();
+    layersIds << layer->id();
+    layers << QVariant::fromValue<QgsWeakMapLayerPointer>( QgsWeakMapLayerPointer( layer ) );
   }
-  scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "map_layers_ids" ), layers_ids, true ) );
+  scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "map_layers_ids" ), layersIds, true ) );
+  scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "map_layers" ), layers, true ) );
 
   scope->addFunction( QStringLiteral( "is_layer_visible" ), new GetLayerVisibility( mapSettings.layers() ) );
 

tests/src/core/testqgslayoutitem.cpp

@@ -1432,11 +1432,15 @@ void TestQgsLayoutItem::itemVariablesFunction()
   r = e4.evaluate( &c );
   QCOMPARE( r.toString(), QString( "degrees" ) );
 
-  QgsVectorLayer *layer = new QgsVectorLayer( QStringLiteral( "Point?field=id_a:integer" ), QStringLiteral( "A" ), QStringLiteral( "memory" ) );
-  map->setLayers( QList<QgsMapLayer *>() << layer );
+  std::unique_ptr< QgsVectorLayer > layer = qgis::make_unique< QgsVectorLayer >( QStringLiteral( "Point?field=id_a:integer" ), QStringLiteral( "A" ), QStringLiteral( "memory" ) );
+  std::unique_ptr< QgsVectorLayer > layer2 = qgis::make_unique< QgsVectorLayer >( QStringLiteral( "Point?field=id_a:integer" ), QStringLiteral( "B" ), QStringLiteral( "memory" ) );
+  map->setLayers( QList<QgsMapLayer *>() << layer.get() << layer2.get() );
   QgsExpression e5( QStringLiteral( "map_get( item_variables( 'Map_id' ), 'map_layers_ids' )" ) );
   r = e5.evaluate( &c );
-  QCOMPARE( r.toStringList().join( ',' ), layer->id() );
+  QCOMPARE( r.toStringList().join( ',' ), QStringLiteral( "%1,%2" ).arg( layer->id(), layer2->id() ) );
+  e5 = QgsExpression( QStringLiteral( "array_foreach(map_get( item_variables( 'Map_id' ), 'map_layers' ), layer_property(@element, 'name'))" ) );
+  r = e5.evaluate( &c );
+  QCOMPARE( r.toStringList().join( ',' ), QStringLiteral( "A,B" ) );
 }
 
 void TestQgsLayoutItem::variables()