Simplify QgsGeometryEngine code

python/core/geometry/qgsgeometryengine.sip

@@ -85,16 +85,28 @@ class QgsGeometryEngine
 %Docstring
  :rtype: QgsAbstractGeometry
 %End
-    virtual bool centroid( QgsPoint &pt, QString *errorMsg = 0 ) const = 0;
+
+    virtual QgsPoint *centroid( QString *errorMsg = 0 ) const = 0 /Factory/;
 %Docstring
- :rtype: bool
+ Calculates the centroid of this.
+ May return a `None`.
+
+.. versionadded:: 3.0
+ :rtype: QgsPoint
 %End
-    virtual bool pointOnSurface( QgsPoint &pt, QString *errorMsg = 0 ) const = 0;
+
+    virtual QgsPoint *pointOnSurface( QString *errorMsg = 0 ) const = 0 /Factory/;
 %Docstring
- :rtype: bool
+ Calculate a point that is guaranteed to be on the surface of this.
+ May return a `None`.
+
+.. versionadded:: 3.0
+ :rtype: QgsPoint
 %End
+
     virtual QgsAbstractGeometry *convexHull( QString *errorMsg = 0 ) const = 0 /Factory/;
 %Docstring
+ Calculate the convex hull of this.
  :rtype: QgsAbstractGeometry
 %End
 

src/core/geometry/qgsgeometry.cpp

@@ -1581,16 +1581,8 @@ QgsGeometry QgsGeometry::centroid() const
   }
 
   QgsGeos geos( d->geometry );
-  std::unique_ptr<QgsPoint> centroid( new QgsPoint() );
+
-  QString error;
+  return QgsGeometry( geos.centroid( &d->error ) );
-  bool ok = geos.centroid( *centroid.get(), &error );
-  if ( !ok )
-  {
-    QgsGeometry geom;
-    geom.d->error = error;
-    return geom;
-  }
-  return QgsGeometry( centroid.release() );
 }
 
 QgsGeometry QgsGeometry::pointOnSurface() const
@@ -1601,17 +1593,8 @@ QgsGeometry QgsGeometry::pointOnSurface() const
   }
 
   QgsGeos geos( d->geometry );
-  std::unique_ptr<QgsPoint>pt( new QgsPoint() );
 
-  QString error;
+  return QgsGeometry( geos.pointOnSurface( &d->error ) );
-  bool ok = geos.pointOnSurface( *pt.get(), &error );
-  if ( !ok )
-  {
-    QgsGeometry geom;
-    geom.d->error = error;
-    return geom;
-  }
-  return QgsGeometry( pt.release() );
 }
 
 QgsGeometry QgsGeometry::poleOfInaccessibility( double precision, double *distanceToBoundary ) const

src/core/geometry/qgsgeometryengine.h

@@ -75,8 +75,26 @@ class CORE_EXPORT QgsGeometryEngine
     virtual QgsAbstractGeometry *simplify( double tolerance, QString *errorMsg = nullptr ) const = 0 SIP_FACTORY;
     virtual QgsAbstractGeometry *interpolate( double distance, QString *errorMsg = nullptr ) const = 0 SIP_FACTORY;
     virtual QgsAbstractGeometry *envelope( QString *errorMsg = nullptr ) const = 0 SIP_FACTORY;
-    virtual bool centroid( QgsPoint &pt, QString *errorMsg = nullptr ) const = 0;
+
-    virtual bool pointOnSurface( QgsPoint &pt, QString *errorMsg = nullptr ) const = 0;
+    /**
+     * Calculates the centroid of this.
+     * May return a `nullptr`.
+     *
+     * \since QGIS 3.0 the centroid is returned
+     */
+    virtual QgsPoint *centroid( QString *errorMsg = nullptr ) const = 0 SIP_FACTORY;
+
+    /**
+     * Calculate a point that is guaranteed to be on the surface of this.
+     * May return a `nullptr`.
+     *
+     * \since QGIS 3.0 the centroid is returned
+     */
+    virtual QgsPoint *pointOnSurface( QString *errorMsg = nullptr ) const = 0 SIP_FACTORY;
+
+    /**
+     * Calculate the convex hull of this.
+     */
     virtual QgsAbstractGeometry *convexHull( QString *errorMsg = nullptr ) const = 0 SIP_FACTORY;
 
     /**

src/core/geometry/qgsgeos.cpp

@@ -1503,36 +1503,30 @@ QgsAbstractGeometry *QgsGeos::interpolate( double distance, QString *errorMsg )
   return fromGeos( geos.get() );
 }
 
-bool QgsGeos::centroid( QgsPoint &pt, QString *errorMsg ) const
+QgsPoint *QgsGeos::centroid( QString *errorMsg ) const
 {
   if ( !mGeos )
   {
-    return false;
+    return nullptr;
   }
 
   GEOSGeomScopedPtr geos;
+  double x;
+  double y;
+
   try
   {
     geos.reset( GEOSGetCentroid_r( geosinit.ctxt,  mGeos ) );
-  }
-  CATCH_GEOS_WITH_ERRMSG( false );
 
-  if ( !geos )
+    if ( !geos )
-  {
+      return nullptr;
-    return false;
-  }
 
-  try
-  {
-    double x, y;
     GEOSGeomGetX_r( geosinit.ctxt, geos.get(), &x );
     GEOSGeomGetY_r( geosinit.ctxt, geos.get(), &y );
-    pt.setX( x );
-    pt.setY( y );
   }
-  CATCH_GEOS_WITH_ERRMSG( false );
+  CATCH_GEOS_WITH_ERRMSG( nullptr );
 
-  return true;
+  return new QgsPoint( x, y );
 }
 
 QgsAbstractGeometry *QgsGeos::envelope( QString *errorMsg ) const
@@ -1550,13 +1544,16 @@ QgsAbstractGeometry *QgsGeos::envelope( QString *errorMsg ) const
   return fromGeos( geos.get() );
 }
 
-bool QgsGeos::pointOnSurface( QgsPoint &pt, QString *errorMsg ) const
+QgsPoint *QgsGeos::pointOnSurface( QString *errorMsg ) const
 {
   if ( !mGeos )
   {
-    return false;
+    return nullptr;
   }
 
+  double x;
+  double y;
+
   GEOSGeomScopedPtr geos;
   try
   {
@@ -1564,19 +1561,15 @@ bool QgsGeos::pointOnSurface( QgsPoint &pt, QString *errorMsg ) const
 
     if ( !geos || GEOSisEmpty_r( geosinit.ctxt, geos.get() ) != 0 )
     {
-      return false;
+      return nullptr;
     }
 
-    double x, y;
     GEOSGeomGetX_r( geosinit.ctxt, geos.get(), &x );
     GEOSGeomGetY_r( geosinit.ctxt, geos.get(), &y );
-
-    pt.setX( x );
-    pt.setY( y );
   }
-  CATCH_GEOS_WITH_ERRMSG( false );
+  CATCH_GEOS_WITH_ERRMSG( nullptr );
 
-  return true;
+  return new QgsPoint( x, y );
 }
 
 QgsAbstractGeometry *QgsGeos::convexHull( QString *errorMsg ) const

src/core/geometry/qgsgeos.h

@@ -79,8 +79,8 @@ class CORE_EXPORT QgsGeos: public QgsGeometryEngine
     QgsAbstractGeometry *simplify( double tolerance, QString *errorMsg = nullptr ) const override;
     QgsAbstractGeometry *interpolate( double distance, QString *errorMsg = nullptr ) const override;
     QgsAbstractGeometry *envelope( QString *errorMsg = nullptr ) const override;
-    bool centroid( QgsPoint &pt, QString *errorMsg = nullptr ) const override;
+    QgsPoint *centroid( QString *errorMsg = nullptr ) const override;
-    bool pointOnSurface( QgsPoint &pt, QString *errorMsg = nullptr ) const override;
+    QgsPoint *pointOnSurface( QString *errorMsg = nullptr ) const override;
     QgsAbstractGeometry *convexHull( QString *errorMsg = nullptr ) const override;
     double distance( const QgsAbstractGeometry *geom, QString *errorMsg = nullptr ) const override;
     bool intersects( const QgsAbstractGeometry *geom, QString *errorMsg = nullptr ) const override;