[convert to curve] style

# Conflicts:
#	src/app/vertextool/qgsvertextool.cpp

Author: olivierdalang

python/core/auto_generated/geometry/qgscompoundcurve.sip.in

@@ -126,6 +126,17 @@ Adds a vertex to the end of the geometry.
 Condenses the curves in this geometry by combining adjacent linestrings a to a single continuous linestring,
 and combining adjacent circularstrings to a single continuous circularstring.
 
+.. versionadded:: 3.20
+%End
+
+    bool toggleCircularAtVertex( QgsVertexId position );
+%Docstring
+Converts the vertex at the given position from/to circular
+
+:return: ``False`` if atVertex does not correspond to a valid vertex
+         on this geometry (including if this geometry is a Point),
+         or if the specified vertex can't be converted (e.g. start/end points).
+
 .. versionadded:: 3.20
 %End
 

src/core/geometry/qgscompoundcurve.cpp

@@ -915,7 +915,7 @@ QVector< QPair<int, QgsVertexId> > QgsCompoundCurve::curveVertexId( QgsVertexId
   return curveIds;
 }
 
-bool QgsCompoundCurve::convertVertex( QgsVertexId position )
+bool QgsCompoundCurve::toggleCircularAtVertex( QgsVertexId position )
 {
 
   // First we find out the sub-curves that are contain that vertex.

src/core/geometry/qgscompoundcurve.h

@@ -116,6 +116,16 @@ class CORE_EXPORT QgsCompoundCurve: public QgsCurve
      */
     void condenseCurves();
 
+    /**
+     * Converts the vertex at the given position from/to circular
+     * \returns FALSE if atVertex does not correspond to a valid vertex
+     * on this geometry (including if this geometry is a Point),
+     * or if the specified vertex can't be converted (e.g. start/end points).
+     *
+     * \since QGIS 3.20
+     */
+    bool toggleCircularAtVertex( QgsVertexId position );
+
     void draw( QPainter &p ) const override;
     void transform( const QgsCoordinateTransform &ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform, bool transformZ = false ) override  SIP_THROW( QgsCsException );
     void transform( const QTransform &t, double zTranslate = 0.0, double zScale = 1.0, double mTranslate = 0.0, double mScale = 1.0 ) override;
@@ -124,7 +134,6 @@ class CORE_EXPORT QgsCompoundCurve: public QgsCurve
     bool insertVertex( QgsVertexId position, const QgsPoint &vertex ) override;
     bool moveVertex( QgsVertexId position, const QgsPoint &newPos ) override;
     bool deleteVertex( QgsVertexId position ) override;
-    bool convertVertex( QgsVertexId position );
     double closestSegment( const QgsPoint &pt, QgsPoint &segmentPt SIP_OUT, QgsVertexId &vertexAfter SIP_OUT, int *leftOf SIP_OUT = nullptr, double epsilon = 4 * std::numeric_limits<double>::epsilon() ) const override;
     bool pointAt( int node, QgsPoint &point, QgsVertexId::VertexType &type ) const override;
     void sumUpArea( double &sum SIP_OUT ) const override;

src/core/geometry/qgsgeometry.cpp

@@ -578,15 +578,15 @@ bool QgsGeometry::toggleCircularAtVertex( int atVertex )
   if ( cpdCurve != nullptr )
   {
     // If the geom is a already compound curve, we convert inplace, and we're done
-    success = cpdCurve->convertVertex( id );
+    success = cpdCurve->toggleCircularAtVertex( id );
   }
   else
   {
-    // TODO : move this block before the above, so we call convertVertex only in one place
+    // TODO : move this block before the above, so we call toggleCircularAtVertex only in one place
     // If the geom is a linestring or cirularstring, we create a compound curve
     std::unique_ptr<QgsCompoundCurve> cpdCurve = std::make_unique<QgsCompoundCurve>();
     cpdCurve->addCurve( curve->clone() );
-    success = cpdCurve->convertVertex( QgsVertexId( -1, -1, id.vertex ) );
+    success = cpdCurve->toggleCircularAtVertex( QgsVertexId( -1, -1, id.vertex ) );
 
     // In that case, we must also reassign the instances
     if ( success )