fix face/vertex count during editing

python/core/auto_generated/mesh/qgsmesheditor.sip.in

@@ -210,6 +210,16 @@ Return ``True`` if the edited mesh is consistent
 %Docstring
 Returns ``True`` if an edge of face is closest than the tolerance from the ``point`` in triangular mesh coordinate
 Returns also the face index and the edge position in ``faceIndex`` and ``edgePosition``
+%End
+
+    int effectiveFacesCount() const;
+%Docstring
+Returns the effective count of faces, that is non void faces in the mesh
+%End
+
+    int effectiveVerticesCount() const;
+%Docstring
+Returns the effective count of vertices, that is non void vertices in the mesh
 %End
 
   signals:

python/core/auto_generated/mesh/qgsmeshlayer.sip.in

@@ -808,13 +808,21 @@ Returns whether the mesh contains at mesh elements of given type
 %Docstring
 Returns the vertices count of the mesh frame
 
+.. note::
+
+   during mesh editing, some vertices can be void and are not included in this returned value
+
 .. versionadded:: 3.22
 %End
 
     int meshFaceCount() const;
 %Docstring
 Returns the faces count of the mesh frame
 
+.. note::
+
+   during mesh editing, some faces can be void and are not included in this returned value
+
 .. versionadded:: 3.22
 %End
 

src/core/mesh/qgsmesheditor.cpp

@@ -65,6 +65,8 @@ QgsMeshEditingError QgsMeshEditor::initialize()
 {
   QgsMeshEditingError error;
   mTopologicalMesh = QgsTopologicalMesh::createTopologicalMesh( mMesh, mMaximumVerticesPerFace, error );
+  mEffectiveFacesCount = mMesh->faceCount();
+  mEffectiveVerticesCount = mMesh->vertexCount();
   return error;
 }
 
@@ -197,6 +199,8 @@ void QgsMeshEditor::applyEdit( QgsMeshEditor::Edit &edit )
          !edit.topologicalChanges.verticesToRemoveIndexes().isEmpty() ||
          !edit.topologicalChanges.addedVertices().isEmpty() ) )
     mZValueDatasetGroup->setStatisticObsolete();
+
+  updateElementsCount( edit.topologicalChanges );
 }
 
 void QgsMeshEditor::reverseEdit( QgsMeshEditor::Edit &edit )
@@ -209,6 +213,8 @@ void QgsMeshEditor::reverseEdit( QgsMeshEditor::Edit &edit )
          !edit.topologicalChanges.verticesToRemoveIndexes().isEmpty() ||
          !edit.topologicalChanges.addedVertices().isEmpty() ) )
     mZValueDatasetGroup->setStatisticObsolete();
+
+  updateElementsCount( edit.topologicalChanges, false );
 }
 
 void QgsMeshEditor::applyAddVertex( QgsMeshEditor::Edit &edit, const QgsMeshVertex &vertex, double tolerance )
@@ -239,6 +245,8 @@ void QgsMeshEditor::applyAddVertex( QgsMeshEditor::Edit &edit, const QgsMeshVert
 
   if ( mZValueDatasetGroup )
     mZValueDatasetGroup->setStatisticObsolete();
+
+  updateElementsCount( edit.topologicalChanges );
 }
 
 void QgsMeshEditor::applyRemoveVertexFillHole( QgsMeshEditor::Edit &edit, int vertexIndex )
@@ -247,6 +255,8 @@ void QgsMeshEditor::applyRemoveVertexFillHole( QgsMeshEditor::Edit &edit, int ve
 
   if ( mZValueDatasetGroup )
     mZValueDatasetGroup->setStatisticObsolete();
+
+  updateElementsCount( edit.topologicalChanges );
 }
 
 void QgsMeshEditor::applyRemoveVerticesWithoutFillHole( QgsMeshEditor::Edit &edit, const QList<int> &verticesIndexes )
@@ -255,16 +265,22 @@ void QgsMeshEditor::applyRemoveVerticesWithoutFillHole( QgsMeshEditor::Edit &edi
 
   if ( mZValueDatasetGroup )
     mZValueDatasetGroup->setStatisticObsolete();
+
+  updateElementsCount( edit.topologicalChanges );
 }
 
 void QgsMeshEditor::applyAddFaces( QgsMeshEditor::Edit &edit, const QgsTopologicalMesh::TopologicalFaces &faces )
 {
   applyEditOnTriangularMesh( edit,  mTopologicalMesh.addFaces( faces ) );
+
+  updateElementsCount( edit.topologicalChanges );
 }
 
 void QgsMeshEditor::applyRemoveFaces( QgsMeshEditor::Edit &edit, const QList<int> &faceToRemoveIndex )
 {
   applyEditOnTriangularMesh( edit, mTopologicalMesh.removeFaces( faceToRemoveIndex ) );
+
+  updateElementsCount( edit.topologicalChanges );
 }
 
 void QgsMeshEditor::applyChangeZValue( QgsMeshEditor::Edit &edit, const QList<int> &verticesIndexes, const QList<double> &newValues )
@@ -283,16 +299,29 @@ void QgsMeshEditor::applyChangeXYValue( QgsMeshEditor::Edit &edit, const QList<i
 void QgsMeshEditor::applyFlipEdge( QgsMeshEditor::Edit &edit, int vertexIndex1, int vertexIndex2 )
 {
   applyEditOnTriangularMesh( edit, mTopologicalMesh.flipEdge( vertexIndex1, vertexIndex2 ) );
+
+  updateElementsCount( edit.topologicalChanges );
 }
 
 void QgsMeshEditor::applyMerge( QgsMeshEditor::Edit &edit, int vertexIndex1, int vertexIndex2 )
 {
   applyEditOnTriangularMesh( edit, mTopologicalMesh.merge( vertexIndex1, vertexIndex2 ) );
+
+  updateElementsCount( edit.topologicalChanges );
 }
 
 void QgsMeshEditor::applySplit( QgsMeshEditor::Edit &edit, int faceIndex )
 {
   applyEditOnTriangularMesh( edit, mTopologicalMesh.splitFace( faceIndex ) );
+
+  updateElementsCount( edit.topologicalChanges );
+}
+
+void QgsMeshEditor::applyAdvancedEdit( QgsMeshEditor::Edit &edit, QgsMeshAdvancedEditing *editing )
+{
+  applyEditOnTriangularMesh( edit, editing->apply( this ) );
+
+  updateElementsCount( edit.topologicalChanges );
 }
 
 void QgsMeshEditor::applyEditOnTriangularMesh( QgsMeshEditor::Edit &edit, const QgsTopologicalMesh::Changes &topologicChanges )
@@ -304,9 +333,19 @@ void QgsMeshEditor::applyEditOnTriangularMesh( QgsMeshEditor::Edit &edit, const
   edit.triangularMeshChanges = triangularChanges;
 }
 
-void QgsMeshEditor::applyAdvancedEdit( QgsMeshEditor::Edit &edit, QgsMeshAdvancedEditing *editing )
+void QgsMeshEditor::updateElementsCount( const QgsTopologicalMesh::Changes &changes, bool apply )
 {
-  applyEditOnTriangularMesh( edit, editing->apply( this ) );
+  if ( apply )
+  {
+    mEffectiveFacesCount += changes.addedFaces().count() - changes.removedFaces().count();
+    mEffectiveVerticesCount += changes.addedVertices().count() - changes.verticesToRemoveIndexes().count();
+  }
+  else
+  {
+    //reverse
+    mEffectiveFacesCount -= changes.addedFaces().count() - changes.removedFaces().count();
+    mEffectiveVerticesCount -= changes.addedVertices().count() - changes.verticesToRemoveIndexes().count();
+  }
 }
 
 bool QgsMeshEditor::checkConsistency() const
@@ -380,6 +419,16 @@ bool QgsMeshEditor::edgeIsClose( QgsPointXY point, double tolerance, int &faceIn
 
 }
 
+int QgsMeshEditor::effectiveFacesCount() const
+{
+  return mEffectiveFacesCount;
+}
+
+int QgsMeshEditor::effectiveVerticesCount() const
+{
+  return mEffectiveVerticesCount;
+}
+
 QgsMeshEditingError QgsMeshEditor::removeFaces( const QList<int> &facesToRemove )
 {
   QgsMeshEditingError error = mTopologicalMesh.canFacesBeRemoved( facesToRemove );
@@ -846,6 +895,8 @@ bool QgsMeshEditor::reindex( bool renumbering )
   mTopologicalMesh.reindex();
   mUndoStack->clear();
   QgsMeshEditingError error = initialize();
+  mEffectiveFacesCount = mMesh->faceCount();
+  mEffectiveVerticesCount = mMesh->vertexCount();
 
   if ( error.errorType != Qgis::MeshEditingErrorType::NoError )
     return false;

src/core/mesh/qgsmesheditor.h

@@ -238,6 +238,12 @@ class CORE_EXPORT QgsMeshEditor : public QObject
      */
     bool edgeIsClose( QgsPointXY point, double tolerance, int &faceIndex, int &edgePosition );
 
+    //! Returns the effective count of faces, that is non void faces in the mesh
+    int effectiveFacesCount() const;
+
+    //! Returns the effective count of vertices, that is non void vertices in the mesh
+    int effectiveVerticesCount() const;
+
   signals:
     //! Emitted when the mesh is edited
     void meshEdited();
@@ -248,6 +254,8 @@ class CORE_EXPORT QgsMeshEditor : public QObject
     QgsTriangularMesh *mTriangularMesh = nullptr;
     int mMaximumVerticesPerFace = 0;
     QgsMeshDatasetGroup *mZValueDatasetGroup = nullptr;
+    int mEffectiveVerticesCount = 0;
+    int mEffectiveFacesCount = 0;
 
     QVector<QgsMeshFace> prepareFaces( const QVector<QgsMeshFace> &faces, QgsMeshEditingError &error );
 
@@ -276,6 +284,8 @@ class CORE_EXPORT QgsMeshEditor : public QObject
 
     void applyEditOnTriangularMesh( Edit &edit, const QgsTopologicalMesh::Changes &topologicChanges );
 
+    void updateElementsCount( const QgsTopologicalMesh::Changes &changes, bool apply = true );
+
     friend class TestQgsMeshEditor;
     friend class QgsMeshLayerUndoCommandMeshEdit;
     friend class QgsMeshLayerUndoCommandAddVertices;

src/core/mesh/qgsmeshlayer.cpp

@@ -1060,7 +1060,7 @@ bool QgsMeshLayer::contains( const QgsMesh::ElementType &type ) const
 int QgsMeshLayer::meshVertexCount() const
 {
   if ( mMeshEditor )
-    return mNativeMesh->vertexCount();
+    return mMeshEditor->effectiveVerticesCount();
   else if ( mDataProvider )
     return mDataProvider->vertexCount();
   else return 0;
@@ -1069,7 +1069,7 @@ int QgsMeshLayer::meshVertexCount() const
 int QgsMeshLayer::meshFaceCount() const
 {
   if ( mMeshEditor )
-    return mNativeMesh->faceCount();
+    return mMeshEditor->effectiveFacesCount();
   else if ( mDataProvider )
     return mDataProvider->faceCount();
   else return 0;

src/core/mesh/qgsmeshlayer.h

@@ -813,13 +813,17 @@ class CORE_EXPORT QgsMeshLayer : public QgsMapLayer
     /**
     * Returns the vertices count of the mesh frame
     *
+    * \note during mesh editing, some vertices can be void and are not included in this returned value
+    *
     *  \since QGIS 3.22
     */
     int meshVertexCount() const;
 
     /**
     * Returns the faces count of the mesh frame
     *
+    * \note during mesh editing, some faces can be void and are not included in this returned value
+    *
     * \since QGIS 3.22
     */
     int meshFaceCount() const;

tests/src/app/testqgsmaptooleditmesh.cpp

@@ -85,7 +85,7 @@ void TestQgsMapToolEditMesh::editMesh()
   QCOMPARE( meshLayerQuadFlower->meshEditor()->freeVerticesIndexes().count(), 0 );
 
   tool.mouseDoubleClick( 1500, 2800, Qt::LeftButton ); //add a vertex on the face 0
-  QCOMPARE( meshLayerQuadFlower->meshFaceCount(), 9 );
+  QCOMPARE( meshLayerQuadFlower->meshFaceCount(), 8 );
   QCOMPARE( meshLayerQuadFlower->meshVertexCount(), 9 );
   QCOMPARE( meshLayerQuadFlower->meshEditor()->freeVerticesIndexes().count(), 0 );
 
@@ -103,19 +103,19 @@ void TestQgsMapToolEditMesh::editMesh()
 
   // redo
   tool.mouseDoubleClick( 1500, 2800, Qt::LeftButton );
-  QCOMPARE( meshLayerQuadFlower->meshFaceCount(), 9 );
+  QCOMPARE( meshLayerQuadFlower->meshFaceCount(), 8 );
   QCOMPARE( meshLayerQuadFlower->meshVertexCount(), 9 );
   QCOMPARE( meshLayerQuadFlower->meshEditor()->freeVerticesIndexes().count(), 0 );
 
   // attempt to add a vertex on place of existing one
   tool.mouseDoubleClick( 2500, 2500, Qt::LeftButton );
-  QCOMPARE( meshLayerQuadFlower->meshFaceCount(), 9 );
+  QCOMPARE( meshLayerQuadFlower->meshFaceCount(), 8 );
   QCOMPARE( meshLayerQuadFlower->meshVertexCount(), 9 );
   QCOMPARE( meshLayerQuadFlower->meshEditor()->freeVerticesIndexes().count(), 0 );
 
   // add a free vertex
   tool.mouseDoubleClick( 2500, 3500, Qt::LeftButton );  // 9
-  QCOMPARE( meshLayerQuadFlower->meshFaceCount(), 9 );
+  QCOMPARE( meshLayerQuadFlower->meshFaceCount(), 8 );
   QCOMPARE( meshLayerQuadFlower->meshVertexCount(), 10 );
   QCOMPARE( meshLayerQuadFlower->meshEditor()->freeVerticesIndexes().count(), 1 );
 
@@ -130,7 +130,7 @@ void TestQgsMapToolEditMesh::editMesh()
   tool.mouseClick( 2495, 2500, Qt::LeftButton ); // click near the vertex
   tool.mouseClick( 5000, 5000, Qt::RightButton ); // valid the face
 
-  QCOMPARE( meshLayerQuadFlower->meshFaceCount(), 10 );
+  QCOMPARE( meshLayerQuadFlower->meshFaceCount(), 9 );
 
   // Remove vertex 7 and 9
   tool.mouseMove( 1500, 3250 );