[feature][expressions] Add "crs_ellipsoid" property to layer_property function and add layer_crs_ellipsoid variable

resources/function_help/json/layer_property

@@ -8,7 +8,7 @@
     "description": "a string, representing either a layer name or layer ID"
   }, {
     "arg": "property",
-    "description": "a string corresponding to the property to return. Valid options are:<br /><ul><li>name: layer name</li><li>id: layer ID</li><li>title: metadata title string</li><li>abstract: metadata abstract string</li><li>keywords: metadata keywords</li><li>data_url: metadata URL</li><li>attribution: metadata attribution string</li><li>attribution_url: metadata attribution URL</li><li>source: layer source</li><li>min_scale: minimum display scale for layer</li><li>max_scale: maximum display scale for layer</li><li>is_editable: if layer is in edit mode</li><li>crs: layer CRS</li><li>crs_definition: layer CRS full definition</li><li>crs_description: layer CRS description</li><li>extent: layer extent (as a geometry object)</li><li>distance_units: layer distance units</li><li>type: layer type, e.g., Vector or Raster</li><li>storage_type: storage format (vector layers only)</li><li>geometry_type: geometry type, e.g., Point (vector layers only)</li><li>feature_count: approximate feature count for layer (vector layers only)</li><li>path: File path to the layer data source. Only available for file based layers.</li></ul>"
+    "description": "a string corresponding to the property to return. Valid options are:<br /><ul><li>name: layer name</li><li>id: layer ID</li><li>title: metadata title string</li><li>abstract: metadata abstract string</li><li>keywords: metadata keywords</li><li>data_url: metadata URL</li><li>attribution: metadata attribution string</li><li>attribution_url: metadata attribution URL</li><li>source: layer source</li><li>min_scale: minimum display scale for layer</li><li>max_scale: maximum display scale for layer</li><li>is_editable: if layer is in edit mode</li><li>crs: layer CRS</li><li>crs_definition: layer CRS full definition</li><li>crs_description: layer CRS description</li><li>crs_ellipsoid: acronym of the layer CRS ellipsoid</li><li>extent: layer extent (as a geometry object)</li><li>distance_units: layer distance units</li><li>type: layer type, e.g., Vector or Raster</li><li>storage_type: storage format (vector layers only)</li><li>geometry_type: geometry type, e.g., Point (vector layers only)</li><li>feature_count: approximate feature count for layer (vector layers only)</li><li>path: File path to the layer data source. Only available for file based layers.</li></ul>"
   }],
   "examples": [{
     "expression": "layer_property('streets','title')",

src/core/expression/qgsexpression.cpp

@@ -766,6 +766,7 @@ void QgsExpression::initVariableHelp()
   sVariableHelpTexts()->insert( QStringLiteral( "layer_id" ), QCoreApplication::translate( "variable_help", "ID of current layer." ) );
   sVariableHelpTexts()->insert( QStringLiteral( "layer_crs" ), QCoreApplication::translate( "variable_help", "CRS Authority ID of current layer." ) );
   sVariableHelpTexts()->insert( QStringLiteral( "layer" ), QCoreApplication::translate( "variable_help", "The current layer." ) );
+  sVariableHelpTexts()->insert( QStringLiteral( "layer_crs_ellipsoid" ), QCoreApplication::translate( "variable_help", "Ellipsoid acronym of current layer CRS." ) );
 
   //feature variables
   sVariableHelpTexts()->insert( QStringLiteral( "feature" ), QCoreApplication::translate( "variable_help", "The current feature being evaluated. This can be used with the 'attribute' function to evaluate attribute values from the current feature." ) );

src/core/expression/qgsexpressioncontextutils.cpp

@@ -384,6 +384,7 @@ QgsExpressionContextScope *QgsExpressionContextUtils::layerScope( const QgsMapLa
   scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "_layer_crs" ), QVariant::fromValue<QgsCoordinateReferenceSystem>( layer->crs() ), true, true ) );
   scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "layer_crs" ), layer->crs().authid(), true, true ) );
   scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "layer" ), QVariant::fromValue<QgsWeakMapLayerPointer >( QgsWeakMapLayerPointer( const_cast<QgsMapLayer *>( layer ) ) ), true, true ) );
+  scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "layer_crs_ellipsoid" ), layer->crs().ellipsoidAcronym(), true, true ) );
 
   const QgsVectorLayer *vLayer = qobject_cast< const QgsVectorLayer * >( layer );
   if ( vLayer )

src/core/expression/qgsexpressionfunction.cpp

@@ -6493,6 +6493,8 @@ static QVariant fcnGetLayerProperty( const QVariantList &values, const QgsExpres
       return layer->crs().toProj();
     else if ( QString::compare( layerProperty, QStringLiteral( "crs_description" ), Qt::CaseInsensitive ) == 0 )
       return layer->crs().description();
+    else if ( QString::compare( layerProperty, QStringLiteral( "crs_ellipsoid" ), Qt::CaseInsensitive ) == 0 )
+      return layer->crs().ellipsoidAcronym();
     else if ( QString::compare( layerProperty, QStringLiteral( "extent" ), Qt::CaseInsensitive ) == 0 )
     {
       QgsGeometry extentGeom = QgsGeometry::fromRect( layer->extent() );

tests/src/core/testqgsexpression.cpp

@@ -1975,6 +1975,7 @@ class TestQgsExpression: public QObject
       QTest::newRow( "layer_property crs" ) << QStringLiteral( "layer_property('%1','crs')" ).arg( mPointsLayer->name() ) << false << QVariant( "EPSG:4326" );
       QTest::newRow( "layer_property crs_description" ) << QStringLiteral( "layer_property('%1','crs_description')" ).arg( mPointsLayer->name() ) << false << QVariant( "WGS 84" );
       QTest::newRow( "layer_property crs_definition" ) << QStringLiteral( "layer_property('%1','crs_definition')" ).arg( mPointsLayer->name() ) << false << QVariant( "+proj=longlat +datum=WGS84 +no_defs" );
+      QTest::newRow( "layer_property crs_ellipsoid" ) << QStringLiteral( "layer_property('%1','crs_ellipsoid')" ).arg( mPointsLayer->name() ) << false << QVariant( "EPSG:7030" );
       QTest::newRow( "layer_property extent" ) << QStringLiteral( "geom_to_wkt(layer_property('%1','extent'))" ).arg( mPointsLayer->name() ) << false << QVariant( "Polygon ((-118.88888889 22.80020704, -83.33333333 22.80020704, -83.33333333 46.87198068, -118.88888889 46.87198068, -118.88888889 22.80020704))" );
       QTest::newRow( "layer_property distance_units" ) << QStringLiteral( "layer_property('%1','distance_units')" ).arg( mPointsLayer->name() ) << false << QVariant( "degrees" );
       QTest::newRow( "layer_property type" ) << QStringLiteral( "layer_property('%1','type')" ).arg( mPointsLayer->name() ) << false << QVariant( "Vector" );

tests/src/core/testqgsexpressioncontext.cpp

@@ -843,6 +843,7 @@ void TestQgsExpressionContext::layerScope()
   QCOMPARE( context.variable( "layer_name" ).toString(), vectorLayer->name() );
   QCOMPARE( context.variable( "layer_id" ).toString(), vectorLayer->id() );
   QCOMPARE( context.variable( "layer_crs" ).toString(), vectorLayer->sourceCrs().authid() );
+  QCOMPARE( context.variable( "layer_crs_ellipsoid" ).toString(), vectorLayer->sourceCrs().ellipsoidAcronym() );
 
   QgsExpression expProject( QStringLiteral( "var('layer_name')" ) );
   QCOMPARE( expProject.evaluate( &context ).toString(), vectorLayer->name() );