QgsVectorLayer: add addMultiRing and use it in QgsMapToolAddRing

The `QgsMapToolAddRing` adds a ring through the `addRing` method of
`QgsVectorLayerEditUtils` called by this of `QgsVectorLayer`.

The bug described in #23113 indicates that only one of the entities receives the
ring addition when using the map tool.

This is consistent with the documentation of the `addRing` methods.
So, it is by design that the tool works like this.

However, as stated in the ticket, it is best to add the ring to all entities.

In order to avoid an api break, I added a new addMultiRing method that adds the ring on all entities.

Fixes #23113

python/core/auto_generated/vector/qgsvectorlayer.sip.in

@@ -1384,6 +1384,37 @@ Adds a ring to polygon/multipolygon features (takes ownership)
    changes can be discarded by calling :py:func:`~QgsVectorLayer.rollBack`.
 %End
 
+    Qgis::GeometryOperationResult addMultiRing( QgsCurve *ring /Transfer/, QgsFeatureIds *featureIds = 0 ) /PyName=addMultiCurvedRing/;
+%Docstring
+Adds a ring to polygon/multipolygon features (takes ownership)
+
+:param ring: ring to add
+:param featureIds: if specified, features ID for features ring was added to will be stored in this parameter
+
+:return: Qgis.GeometryOperationResult
+
+         - Success
+         - LayerNotEditable
+         - AddRingNotInExistingFeature
+         - InvalidInputGeometryType
+         - AddRingNotClosed
+         - AddRingNotValid
+         - AddRingCrossesExistingRings
+
+.. note::
+
+   available in Python as addMultiCurvedRing
+
+.. note::
+
+   Calls to :py:func:`~QgsVectorLayer.addMultiRing` are only valid for layers in which edits have been enabled
+   by a call to :py:func:`~QgsVectorLayer.startEditing`. Changes made to features using this method are not committed
+   to the underlying data provider until a :py:func:`~QgsVectorLayer.commitChanges` call is made. Any uncommitted
+   changes can be discarded by calling :py:func:`~QgsVectorLayer.rollBack`.
+
+.. seealso:: :py:func:`addRing`
+%End
+
  Qgis::GeometryOperationResult addPart( const QList<QgsPointXY> &ring ) /Deprecated/;
 %Docstring
 Adds a new part polygon to a multipart feature

python/core/auto_generated/vector/qgsvectorlayereditutils.sip.in

@@ -84,6 +84,18 @@ Adds a ring to polygon/multipolygon features
                          all intersecting features are tested and the ring is added to the first valid feature.
 :param modifiedFeatureId: if specified, feature ID for feature that ring was added to will be stored in this parameter
 
+:return: OperationResult result code: success or reason of failure
+%End
+
+    Qgis::GeometryOperationResult addMultiRing( QgsCurve *ring, const QgsFeatureIds &targetFeatureIds = QgsFeatureIds(), QgsFeatureIds *modifiedFeatureIds = 0 );
+%Docstring
+Adds a ring to polygon/multipolygon features
+
+:param ring: ring to add
+:param targetFeatureIds: if specified, only these features will be the candidates for adding a ring. Otherwise
+                         all intersecting features are tested and the ring is added to all valid features.
+:param modifiedFeatureIds: if specified, feature IDS for features that ring was added to will be stored in this parameter
+
 :return: OperationResult result code: success or reason of failure
 %End
 

src/app/qgsmaptooladdring.cpp

@@ -68,7 +68,7 @@ void QgsMapToolAddRing::polygonCaptured( const QgsCurvePolygon *polygon )
     return;
 
   vlayer->beginEditCommand( tr( "Ring added" ) );
-  const Qgis::GeometryOperationResult addRingReturnCode = vlayer->addRing( polygon->exteriorRing()->clone() );
+  const Qgis::GeometryOperationResult addRingReturnCode = vlayer->addMultiRing( polygon->exteriorRing()->clone() );
   QString errorMessage;
   switch ( addRingReturnCode )
   {

src/core/vector/qgsvectorlayer.cpp

@@ -1323,6 +1323,44 @@ Qgis::GeometryOperationResult QgsVectorLayer::addRing( QgsCurve *ring, QgsFeatur
   return result;
 }
 
+Qgis::GeometryOperationResult QgsVectorLayer::addMultiRing( QgsCurve *ring, QgsFeatureIds *featureIds )
+{
+  if ( !isValid() || !mEditBuffer || !mDataProvider )
+  {
+    delete ring;
+    return Qgis::GeometryOperationResult::LayerNotEditable;
+  }
+
+  if ( !ring )
+  {
+    return Qgis::GeometryOperationResult::InvalidInputGeometryType;
+  }
+
+  if ( !ring->isClosed() )
+  {
+    delete ring;
+    return Qgis::GeometryOperationResult::AddRingNotClosed;
+  }
+
+  QgsVectorLayerEditUtils utils( this );
+  Qgis::GeometryOperationResult result = Qgis::GeometryOperationResult::AddRingNotInExistingFeature;
+
+  //first try with selected features
+  if ( !mSelectedFeatureIds.isEmpty() )
+  {
+    result = utils.addMultiRing( static_cast< QgsCurve * >( ring->clone() ), mSelectedFeatureIds, featureIds );
+  }
+
+  if ( result != Qgis::GeometryOperationResult::Success )
+  {
+    //try with all intersecting features
+    result = utils.addMultiRing( static_cast< QgsCurve * >( ring->clone() ), QgsFeatureIds(), featureIds );
+  }
+
+  delete ring;
+  return result;
+}
+
 Qgis::GeometryOperationResult QgsVectorLayer::addPart( const QList<QgsPointXY> &points )
 {
   QgsPointSequence pts;

src/core/vector/qgsvectorlayer.h

@@ -1391,6 +1391,29 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer, public QgsExpressionConte
      */
     Q_INVOKABLE Qgis::GeometryOperationResult addRing( QgsCurve *ring SIP_TRANSFER, QgsFeatureId *featureId = nullptr ) SIP_PYNAME( addCurvedRing );
 
+    /**
+     * Adds a ring to polygon/multipolygon features (takes ownership)
+     * \param ring ring to add
+     * \param featureIds if specified, features ID for features ring was added to will be stored in this parameter
+     * \returns Qgis::GeometryOperationResult
+     *
+     * - Success
+     * - LayerNotEditable
+     * - AddRingNotInExistingFeature
+     * - InvalidInputGeometryType
+     * - AddRingNotClosed
+     * - AddRingNotValid
+     * - AddRingCrossesExistingRings
+     *
+     * \note available in Python as addMultiCurvedRing
+     * \note Calls to addMultiRing() are only valid for layers in which edits have been enabled
+     * by a call to startEditing(). Changes made to features using this method are not committed
+     * to the underlying data provider until a commitChanges() call is made. Any uncommitted
+     * changes can be discarded by calling rollBack().
+     * \see addRing
+     */
+    Q_INVOKABLE Qgis::GeometryOperationResult addMultiRing( QgsCurve *ring SIP_TRANSFER, QgsFeatureIds *featureIds = nullptr ) SIP_PYNAME( addMultiCurvedRing );
+
     /**
      * Adds a new part polygon to a multipart feature
      * \returns Qgis::GeometryOperationResult

src/core/vector/qgsvectorlayereditutils.cpp

@@ -118,6 +118,61 @@ Qgis::VectorEditResult QgsVectorLayerEditUtils::deleteVertex( QgsFeatureId featu
   return !geometry.isNull() ? Qgis::VectorEditResult::Success : Qgis::VectorEditResult::EmptyGeometry;
 }
 
+
+static
+Qgis::GeometryOperationResult _addRing( QgsVectorLayer *layer, QgsCurve *ring, const QgsFeatureIds &targetFeatureIds, QgsFeatureIds *modifiedFeatureIds, bool firstOne = true )
+{
+
+  if ( !layer || !layer->isSpatial() )
+  {
+    delete ring;
+    return Qgis::GeometryOperationResult::AddRingNotInExistingFeature;
+  }
+
+  Qgis::GeometryOperationResult addRingReturnCode = Qgis::GeometryOperationResult::AddRingNotInExistingFeature; //default: return code for 'ring not inserted'
+  QgsFeature f;
+
+  QgsFeatureIterator fit;
+  if ( !targetFeatureIds.isEmpty() )
+  {
+    //check only specified features
+    fit = layer->getFeatures( QgsFeatureRequest().setFilterFids( targetFeatureIds ) );
+  }
+  else
+  {
+    //check all intersecting features
+    QgsRectangle bBox = ring->boundingBox();
+    fit = layer->getFeatures( QgsFeatureRequest().setFilterRect( bBox ).setFlags( QgsFeatureRequest::ExactIntersect ) );
+  }
+
+  //find first valid feature we can add the ring to
+  while ( fit.nextFeature( f ) )
+  {
+    if ( !f.hasGeometry() )
+      continue;
+
+    //add ring takes ownership of ring, and deletes it if there's an error
+    QgsGeometry g = f.geometry();
+
+    addRingReturnCode = g.addRing( static_cast< QgsCurve * >( ring->clone() ) );
+    if ( addRingReturnCode == Qgis::GeometryOperationResult::Success )
+    {
+      layer->changeGeometry( f.id(), g );
+      if ( modifiedFeatureIds )
+      {
+        modifiedFeatureIds->insert( f.id() );
+        if ( firstOne )
+        {
+          break;
+        }
+      }
+
+    }
+  }
+
+  delete ring;
+  return addRingReturnCode;
+}
 Qgis::GeometryOperationResult QgsVectorLayerEditUtils::addRing( const QVector<QgsPointXY> &ring, const QgsFeatureIds &targetFeatureIds, QgsFeatureId *modifiedFeatureId )
 {
   QgsPointSequence l;
@@ -136,53 +191,23 @@ Qgis::GeometryOperationResult QgsVectorLayerEditUtils::addRing( const QgsPointSe
 
 Qgis::GeometryOperationResult QgsVectorLayerEditUtils::addRing( QgsCurve *ring, const QgsFeatureIds &targetFeatureIds, QgsFeatureId *modifiedFeatureId )
 {
-  if ( !mLayer->isSpatial() )
+  if ( modifiedFeatureId )
   {
-    delete ring;
-    return Qgis::GeometryOperationResult::AddRingNotInExistingFeature;
+    QgsFeatureIds *modifiedFeatureIds = new QgsFeatureIds;
+    Qgis::GeometryOperationResult result = _addRing( mLayer, ring, targetFeatureIds, modifiedFeatureIds, true );
+    *modifiedFeatureId = *modifiedFeatureIds->begin();
+    return result;
   }
-
-  Qgis::GeometryOperationResult addRingReturnCode = Qgis::GeometryOperationResult::AddRingNotInExistingFeature; //default: return code for 'ring not inserted'
-  QgsFeature f;
-
-  QgsFeatureIterator fit;
-  if ( !targetFeatureIds.isEmpty() )
-  {
-    //check only specified features
-    fit = mLayer->getFeatures( QgsFeatureRequest().setFilterFids( targetFeatureIds ) );
-  }
-  else
-  {
-    //check all intersecting features
-    QgsRectangle bBox = ring->boundingBox();
-    fit = mLayer->getFeatures( QgsFeatureRequest().setFilterRect( bBox ).setFlags( QgsFeatureRequest::ExactIntersect ) );
-  }
-
-  //find first valid feature we can add the ring to
-  while ( fit.nextFeature( f ) )
-  {
-    if ( !f.hasGeometry() )
-      continue;
-
-    //add ring takes ownership of ring, and deletes it if there's an error
-    QgsGeometry g = f.geometry();
-
-    addRingReturnCode = g.addRing( static_cast< QgsCurve * >( ring->clone() ) );
-    if ( addRingReturnCode == Qgis::GeometryOperationResult::Success )
-    {
-      mLayer->changeGeometry( f.id(), g );
-      if ( modifiedFeatureId )
-        *modifiedFeatureId = f.id();
-
-      //setModified( true, true );
-      break;
-    }
-  }
-
-  delete ring;
-  return addRingReturnCode;
+  return _addRing( mLayer, ring, targetFeatureIds, nullptr, true );
 }
 
+Qgis::GeometryOperationResult QgsVectorLayerEditUtils::addMultiRing( QgsCurve *ring, const QgsFeatureIds &targetFeatureIds, QgsFeatureIds *modifiedFeatureIds )
+{
+  return _addRing( mLayer, ring, targetFeatureIds, modifiedFeatureIds, false );
+}
+
+
+
 Qgis::GeometryOperationResult QgsVectorLayerEditUtils::addPart( const QVector<QgsPointXY> &points, QgsFeatureId featureId )
 {
   QgsPointSequence l;

src/core/vector/qgsvectorlayereditutils.h

@@ -91,6 +91,16 @@ class CORE_EXPORT QgsVectorLayerEditUtils
      */
     Qgis::GeometryOperationResult addRing( const QgsPointSequence &ring, const QgsFeatureIds &targetFeatureIds = QgsFeatureIds(), QgsFeatureId *modifiedFeatureId = nullptr );
 
+    /**
+     * Adds a ring to polygon/multipolygon features
+     * \param ring ring to add
+     * \param targetFeatureIds if specified, only these features will be the candidates for adding a ring. Otherwise
+     * all intersecting features are tested and the ring is added to all valid features.
+     * \param modifiedFeatureIds if specified, feature IDS for features that ring was added to will be stored in this parameter
+     * \return OperationResult result code: success or reason of failure
+     */
+    Qgis::GeometryOperationResult addMultiRing( QgsCurve *ring, const QgsFeatureIds &targetFeatureIds = QgsFeatureIds(), QgsFeatureIds *modifiedFeatureIds = nullptr );
+
     /**
      * Adds a ring to polygon/multipolygon features
      * \param ring ring to add