add map_layers variable for MapLayoutItem

Gustry · nyalldawson · commit 5bc848c05746 · 2018-08-22T05:16:04.000+10:00
diff --git a/src/core/layout/qgslayoutitemmap.cpp b/src/core/layout/qgslayoutitemmap.cpp
@@ -1155,8 +1155,19 @@ 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 ) );
+
   context.appendScope( scope );
 
+  // The scope map_layers_ids has been added to the context, only now we can call layersToRender
+  const QList<QgsMapLayer *> layersInMap = layersToRender( &context );
+  for ( QgsMapLayer *layer : layersInMap )
+  {
+    layers_ids << layer->id();
+  }
+  scope->setVariable( QStringLiteral( "map_layers_ids" ), layers_ids );
+
   return context;
 }
 
diff --git a/src/core/qgsexpressioncontext.cpp b/src/core/qgsexpressioncontext.cpp
@@ -995,6 +995,14 @@ 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;
+  const QList<QgsMapLayer *> layersInMap = mapSettings.layers();
+  for ( QgsMapLayer *layer : layersInMap )
+  {
+    layers_ids << layer->id();
+  }
+  scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "map_layers_ids" ), layers_ids, true ) );
+
   scope->addFunction( QStringLiteral( "is_layer_visible" ), new GetLayerVisibility( mapSettings.layers() ) );
 
   return scope;
diff --git a/tests/src/core/testqgslayoutitem.cpp b/tests/src/core/testqgslayoutitem.cpp
@@ -1431,6 +1431,12 @@ void TestQgsLayoutItem::itemVariablesFunction()
   QgsExpression e4( QStringLiteral( "map_get( item_variables( 'Map_id' ), 'map_units' )" ) );
   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 );
+  QgsExpression e5( QStringLiteral( "map_get( item_variables( 'Map_id' ), 'map_layers_ids' )" ) );
+  r = e5.evaluate( &c );
+  QCOMPARE( r.toStringList().join( ',' ), layer->id() );
 }
 
 void TestQgsLayoutItem::variables()
