Modernize paste to memory layer code

Author: nyalldawson

src/app/qgisapp.cpp

@@ -8220,18 +8220,15 @@ void QgisApp::pasteFromClipboard( QgsMapLayer *destinationLayer )
 void QgisApp::pasteAsNewVector()
 {
 
-  QgsVectorLayer *layer = pasteToNewMemoryVector();
+  std::unique_ptr< QgsVectorLayer > layer = pasteToNewMemoryVector();
   if ( !layer )
     return;
 
-  saveAsVectorFileGeneral( layer, false );
-
-  delete layer;
+  saveAsVectorFileGeneral( layer.get(), false );
 }
 
 QgsVectorLayer *QgisApp::pasteAsNewMemoryVector( const QString &layerName )
 {
-
   QString layerNameCopy = layerName;
 
   if ( layerNameCopy.isEmpty() )
@@ -8250,36 +8247,36 @@ QgsVectorLayer *QgisApp::pasteAsNewMemoryVector( const QString &layerName )
     }
   }
 
-  QgsVectorLayer *layer = pasteToNewMemoryVector();
+  std::unique_ptr< QgsVectorLayer > layer = pasteToNewMemoryVector();
   if ( !layer )
     return nullptr;
 
   layer->setName( layerNameCopy );
 
   freezeCanvases();
 
-  QgsProject::instance()->addMapLayer( layer );
+  QgsVectorLayer *result = layer.get();
+  QgsProject::instance()->addMapLayer( layer.release() );
 
   freezeCanvases( false );
   refreshMapCanvas();
 
-  return layer;
+  return result;
 }
 
-QgsVectorLayer *QgisApp::pasteToNewMemoryVector()
+std::unique_ptr<QgsVectorLayer> QgisApp::pasteToNewMemoryVector()
 {
-  QgsFields fields = clipboard()->fields();
+  const QgsFields fields = clipboard()->fields();
 
   // Decide geometry type from features, switch to multi type if at least one multi is found
   QMap<QgsWkbTypes::Type, int> typeCounts;
-  QgsFeatureList features = clipboard()->copyOf( fields );
-  for ( int i = 0; i < features.size(); i++ )
+  const QgsFeatureList features = clipboard()->copyOf( fields );
+  for ( const QgsFeature &feature : features )
   {
-    QgsFeature &feature = features[i];
     if ( !feature.hasGeometry() )
       continue;
 
-    QgsWkbTypes::Type type = feature.geometry().wkbType();
+    const QgsWkbTypes::Type type = feature.geometry().wkbType();
 
     if ( type == QgsWkbTypes::Unknown || type == QgsWkbTypes::NoGeometry )
       continue;
@@ -8307,7 +8304,7 @@ QgsVectorLayer *QgisApp::pasteToNewMemoryVector()
     }
   }
 
-  QgsWkbTypes::Type wkbType = !typeCounts.isEmpty() ? typeCounts.keys().value( 0 ) : QgsWkbTypes::NoGeometry;
+  const QgsWkbTypes::Type wkbType = !typeCounts.isEmpty() ? typeCounts.keys().value( 0 ) : QgsWkbTypes::NoGeometry;
 
   if ( features.isEmpty() )
   {
@@ -8325,39 +8322,38 @@ QgsVectorLayer *QgisApp::pasteToNewMemoryVector()
                                QgsMessageBar::INFO, messageTimeout() );
   }
 
-  QgsVectorLayer *layer = QgsMemoryProviderUtils::createMemoryLayer( QStringLiteral( "pasted_features" ), QgsFields(), wkbType, clipboard()->crs() );
+  std::unique_ptr< QgsVectorLayer > layer( QgsMemoryProviderUtils::createMemoryLayer( QStringLiteral( "pasted_features" ), QgsFields(), wkbType, clipboard()->crs() ) );
 
   if ( !layer->isValid() || !layer->dataProvider() )
   {
-    delete layer;
     messageBar()->pushMessage( tr( "Paste features" ),
                                tr( "Cannot create new layer." ),
                                QgsMessageBar::WARNING, messageTimeout() );
     return nullptr;
   }
 
   layer->startEditing();
-  Q_FOREACH ( QgsField f, clipboard()->fields().toList() )
+  for ( const QgsField &f : clipboard()->fields() )
   {
     QgsDebugMsg( QString( "field %1 (%2)" ).arg( f.name(), QVariant::typeToName( f.type() ) ) );
     if ( !layer->addAttribute( f ) )
     {
       messageBar()->pushMessage( tr( "Paste features" ),
                                  tr( "Cannot create field %1 (%2,%3)" ).arg( f.name(), f.typeName(), QVariant::typeToName( f.type() ) ),
                                  QgsMessageBar::WARNING, messageTimeout() );
-      delete layer;
       return nullptr;
     }
   }
 
   // Convert to multi if necessary
-  for ( int i = 0; i < features.size(); i++ )
+  QgsFeatureList convertedFeatures;
+  convertedFeatures.reserve( features.length() );
+  for ( QgsFeature feature : features )
   {
-    QgsFeature &feature = features[i];
     if ( !feature.hasGeometry() )
       continue;
 
-    QgsWkbTypes::Type type = feature.geometry().wkbType();
+    const QgsWkbTypes::Type type = feature.geometry().wkbType();
     if ( type == QgsWkbTypes::Unknown || type == QgsWkbTypes::NoGeometry )
       continue;
 
@@ -8372,11 +8368,11 @@ QgsVectorLayer *QgisApp::pasteToNewMemoryVector()
       g.convertToMultiType();
       feature.setGeometry( g );
     }
+    convertedFeatures.append( feature );
   }
-  if ( ! layer->addFeatures( features ) || !layer->commitChanges() )
+  if ( ! layer->addFeatures( convertedFeatures ) || !layer->commitChanges() )
   {
     QgsDebugMsg( "Cannot add features or commit changes" );
-    delete layer;
     return nullptr;
   }
 

src/app/qgisapp.h

@@ -1751,10 +1751,10 @@ class APP_EXPORT QgisApp : public QMainWindow, private Ui::MainWindow
 
     /**
      * Paste features from clipboard into a new memory layer.
-     *  If no features are in clipboard an empty layer is returned.
-     *  \returns pointer to a new layer or 0 if failed
+     * If no features are in clipboard an empty layer is returned.
+     * Returns a new memory layer or a nullptr if the operation failed.
      */
-    QgsVectorLayer *pasteToNewMemoryVector();
+    std::unique_ptr< QgsVectorLayer > pasteToNewMemoryVector();
 
     //! Returns all annotation items in the canvas
     QList<QgsMapCanvasAnnotationItem *> annotationItems();