QgsExpression::setGeomCalculator now takes a pointer

This allows the calculator to be cleared

python/core/qgsexpression.sip

@@ -99,10 +99,11 @@ class QgsExpression
      * (used by $length, $area and $perimeter functions only). By default, no geometry
      * calculator is set and all distance and area calculations are performed using simple
      * cartesian methods (ie no ellipsoidal calculations).
+     * @param calc geometry calculator. Ownership is not transferred. Set to a nullptr to force
+     * cartesian calculations.
      * @see geomCalculator()
      */
-    //TODO QGIS 3.0 change calc to a pointer, so that calculator can be cleared by passing nullptr
-    void setGeomCalculator( const QgsDistanceArea &calc );
+    void setGeomCalculator( const QgsDistanceArea* calc );
 
     /** Returns the desired distance units for calculations involving geomCalculator(), eg "$length" and "$perimeter".
      * @note distances are only converted when a geomCalculator() has been set

src/app/qgsattributetabledialog.cpp

@@ -443,7 +443,7 @@ void QgsAttributeTableDialog::runFieldCalculation( QgsVectorLayer* layer, const
   QString error;
 
   QgsExpression exp( expression );
-  exp.setGeomCalculator( *myDa );
+  exp.setGeomCalculator( myDa );
   exp.setDistanceUnits( QgsProject::instance()->distanceUnits() );
   exp.setAreaUnits( QgsProject::instance()->areaUnits() );
   bool useGeometry = exp.needsGeometry();
@@ -945,7 +945,7 @@ void QgsAttributeTableDialog::setFilterExpression( const QString& filterString,
 
   QApplication::setOverrideCursor( Qt::WaitCursor );
 
-  filterExpression.setGeomCalculator( myDa );
+  filterExpression.setGeomCalculator( &myDa );
   filterExpression.setDistanceUnits( QgsProject::instance()->distanceUnits() );
   filterExpression.setAreaUnits( QgsProject::instance()->areaUnits() );
   QgsFeatureRequest request( mMainView->masterModel()->request() );

src/app/qgsfieldcalculator.cpp

@@ -164,7 +164,7 @@ void QgsFieldCalculator::accept()
 
   QString calcString = builder->expressionText();
   QgsExpression exp( calcString );
-  exp.setGeomCalculator( myDa );
+  exp.setGeomCalculator( &myDa );
   exp.setDistanceUnits( QgsProject::instance()->distanceUnits() );
   exp.setAreaUnits( QgsProject::instance()->areaUnits() );
 

src/core/qgsexpression.cpp

@@ -3500,9 +3500,13 @@ void QgsExpression::detach()
   }
 }
 
-void QgsExpression::setGeomCalculator( const QgsDistanceArea &calc )
+void QgsExpression::setGeomCalculator( const QgsDistanceArea *calc )
 {
-  d->mCalc = QSharedPointer<QgsDistanceArea>( new QgsDistanceArea( calc ) );
+  detach();
+  if ( calc )
+    d->mCalc = QSharedPointer<QgsDistanceArea>( new QgsDistanceArea( *calc ) );
+  else
+    d->mCalc.clear();
 }
 
 bool QgsExpression::prepare( const QgsExpressionContext *context )
@@ -3633,7 +3637,7 @@ QString QgsExpression::replaceExpressionText( const QString &action, const QgsEx
     if ( distanceArea )
     {
       //if QgsDistanceArea specified for area/distance conversion, use it
-      exp.setGeomCalculator( *distanceArea );
+      exp.setGeomCalculator( distanceArea );
     }
 
     QVariant result = exp.evaluate( context );

src/core/qgsexpression.h

@@ -219,10 +219,11 @@ class CORE_EXPORT QgsExpression
      * (used by $length, $area and $perimeter functions only). By default, no geometry
      * calculator is set and all distance and area calculations are performed using simple
      * cartesian methods (ie no ellipsoidal calculations).
+     * @param calc geometry calculator. Ownership is not transferred. Set to a nullptr to force
+     * cartesian calculations.
      * @see geomCalculator()
      */
-    //TODO QGIS 3.0 change calc to a pointer, so that calculator can be cleared by passing nullptr
-    void setGeomCalculator( const QgsDistanceArea &calc );
+    void setGeomCalculator( const QgsDistanceArea* calc );
 
     /** Returns the desired distance units for calculations involving geomCalculator(), eg "$length" and "$perimeter".
      * @note distances are only converted when a geomCalculator() has been set

src/core/qgsvectorlayerfeatureiterator.cpp

@@ -529,7 +529,7 @@ void QgsVectorLayerFeatureIterator::prepareExpression( int fieldIdx )
   da.setSourceCrs( mSource->mCrsId );
   da.setEllipsoidalMode( true );
   da.setEllipsoid( QgsProject::instance()->readEntry( "Measure", "/Ellipsoid", GEO_NONE ) );
-  exp->setGeomCalculator( da );
+  exp->setGeomCalculator( &da );
   exp->setDistanceUnits( QgsProject::instance()->distanceUnits() );
   exp->setAreaUnits( QgsProject::instance()->areaUnits() );
 

src/gui/qgsexpressionbuilderwidget.cpp

@@ -540,7 +540,7 @@ void QgsExpressionBuilderWidget::on_txtExpressionString_textChanged()
   if ( mLayer )
   {
     // Only set calculator if we have layer, else use default.
-    exp.setGeomCalculator( mDa );
+    exp.setGeomCalculator( &mDa );
 
     if ( !mFeature.isValid() )
     {

tests/src/core/testqgsexpression.cpp

@@ -1685,7 +1685,7 @@ class TestQgsExpression: public QObject
 
       // test area with geomCalculator
       QgsExpression expArea2( "$area" );
-      expArea2.setGeomCalculator( da );
+      expArea2.setGeomCalculator( &da );
       vArea = expArea2.evaluate( &context );
       expected = 1009089817.0;
       QVERIFY( qgsDoubleNear( vArea.toDouble(), expected, 1.0 ) );
@@ -1716,7 +1716,7 @@ class TestQgsExpression: public QObject
 
       // test perimeter with geomCalculator
       QgsExpression expPerimeter2( "$perimeter" );
-      expPerimeter2.setGeomCalculator( da );
+      expPerimeter2.setGeomCalculator( &da );
       vPerimeter = expPerimeter2.evaluate( &context );
       expected = 128289.074;
       QVERIFY( qgsDoubleNear( vPerimeter.toDouble(), expected, 0.001 ) );
@@ -1753,7 +1753,7 @@ class TestQgsExpression: public QObject
 
       // test length with geomCalculator
       QgsExpression expLength2( "$length" );
-      expLength2.setGeomCalculator( da );
+      expLength2.setGeomCalculator( &da );
       vLength = expLength2.evaluate( &context );
       expected = 26932.156;
       QVERIFY( qgsDoubleNear( vLength.toDouble(), expected, 0.001 ) );