Change signature of processFeature so that features are no longer mod…

…ified in place
qgis · Jul 18, 2017 · 29855b3 · 29855b3
1 parent c2cad99
commit 29855b3
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Showing 11 changed files with 25 additions and 26 deletions.
diff --git a/python/core/processing/qgsprocessingalgorithm.sip b/python/core/processing/qgsprocessingalgorithm.sip
@@ -820,15 +820,14 @@ class QgsProcessingFeatureBasedAlgorithm : QgsProcessingAlgorithm
  :rtype: QgsCoordinateReferenceSystem
 %End
 
-    virtual bool processFeature( QgsFeature &feature, QgsProcessingFeedback *feedback ) = 0;
+    virtual QgsFeature processFeature( const QgsFeature &feature, QgsProcessingFeedback *feedback ) = 0;
 %Docstring
  Processes an individual input ``feature`` from the source. Algorithms should implement their
  logic in this method for performing the algorithm's operation (e.g. replacing the feature's
  geometry with the centroid of the original feature geometry for a 'centroid' type
  algorithm).
 
- Implementations should return true if the feature should be kept and added to the algorithm's
- output sink, or false if the feature should be skipped and omitted from the output.
+ Implementations should return the modified feature.
 
  The provided ``feedback`` object can be used to push messages to the log and for giving feedback
  to users. Note that handling of progress reports and algorithm cancelation is handled by
@@ -838,7 +837,7 @@ class QgsProcessingFeatureBasedAlgorithm : QgsProcessingAlgorithm
  prevent the algorithm execution from continuing. This can be annoying for users though as it
  can break valid model execution - so use with extreme caution, and consider using
  ``feedback`` to instead report non-fatal processing failures for features instead.
- :rtype: bool
+ :rtype: QgsFeature
 %End
 
     virtual QVariantMap processAlgorithm( const QVariantMap &parameters,

diff --git a/python/plugins/processing/algs/qgis/AddTableField.py b/python/plugins/processing/algs/qgis/AddTableField.py
@@ -90,4 +90,4 @@ def processFeature(self, feature, feedback):
         attributes = feature.attributes()
         attributes.append(None)
         feature.setAttributes(attributes)
-        return True
+        return feature
diff --git a/python/plugins/processing/algs/qgis/AutoincrementalField.py b/python/plugins/processing/algs/qgis/AutoincrementalField.py
@@ -57,4 +57,4 @@ def processFeature(self, feature, feedback):
         attributes.append(self.current)
         self.current += 1
         feature.setAttributes(attributes)
-        return True
+        return feature
diff --git a/python/plugins/processing/algs/qgis/BoundingBox.py b/python/plugins/processing/algs/qgis/BoundingBox.py
@@ -72,4 +72,4 @@ def processFeature(self, feature, feedback):
 
             feature.setGeometry(output_geometry)
 
-        return True
+        return feature
diff --git a/python/plugins/processing/algs/qgis/DropMZValues.py b/python/plugins/processing/algs/qgis/DropMZValues.py
@@ -91,4 +91,4 @@ def processFeature(self, feature, feedback):
                 new_geom.dropZValue()
             feature.setGeometry(QgsGeometry(new_geom))
 
-        return True
+        return feature
diff --git a/python/plugins/processing/algs/qgis/SetMValue.py b/python/plugins/processing/algs/qgis/SetMValue.py
@@ -83,4 +83,4 @@ def processFeature(self, feature, feedback):
 
             feature.setGeometry(QgsGeometry(new_geom))
 
-        return True
+        return feature
diff --git a/python/plugins/processing/algs/qgis/SetZValue.py b/python/plugins/processing/algs/qgis/SetZValue.py
@@ -83,4 +83,4 @@ def processFeature(self, feature, feedback):
 
             feature.setGeometry(QgsGeometry(new_geom))
 
-        return True
+        return feature
diff --git a/src/core/processing/qgsnativealgorithms.cpp b/src/core/processing/qgsnativealgorithms.cpp
@@ -87,8 +87,9 @@ QgsCentroidAlgorithm *QgsCentroidAlgorithm::createInstance() const
   return new QgsCentroidAlgorithm();
 }
 
-bool QgsCentroidAlgorithm::processFeature( QgsFeature &feature, QgsProcessingFeedback *feedback )
+QgsFeature QgsCentroidAlgorithm::processFeature( const QgsFeature &f, QgsProcessingFeedback *feedback )
 {
+  QgsFeature feature = f;
   if ( feature.hasGeometry() )
   {
     feature.setGeometry( feature.geometry().centroid() );
@@ -97,7 +98,7 @@ bool QgsCentroidAlgorithm::processFeature( QgsFeature &feature, QgsProcessingFee
       feedback->pushInfo( QObject::tr( "Error calculating centroid for feature %1" ).arg( feature.id() ) );
     }
   }
-  return true;
+  return feature;
 }
 //
 // QgsBufferAlgorithm
@@ -548,8 +549,9 @@ bool QgsTransformAlgorithm::prepareAlgorithm( const QVariantMap &parameters, Qgs
   return true;
 }
 
-bool QgsTransformAlgorithm::processFeature( QgsFeature &feature, QgsProcessingFeedback * )
+QgsFeature QgsTransformAlgorithm::processFeature( const QgsFeature &f, QgsProcessingFeedback * )
 {
+  QgsFeature feature = f;
   if ( !mCreatedTransform )
   {
     mCreatedTransform = true;
@@ -568,7 +570,7 @@ bool QgsTransformAlgorithm::processFeature( QgsFeature &feature, QgsProcessingFe
       feature.clearGeometry();
     }
   }
-  return true;
+  return feature;
 }
 
 
@@ -598,8 +600,9 @@ QgsWkbTypes::Type QgsSubdivideAlgorithm::outputWkbType( QgsWkbTypes::Type inputW
   return QgsWkbTypes::multiType( inputWkbType );
 }
 
-bool QgsSubdivideAlgorithm::processFeature( QgsFeature &feature, QgsProcessingFeedback *feedback )
+QgsFeature QgsSubdivideAlgorithm::processFeature( const QgsFeature &f, QgsProcessingFeedback *feedback )
 {
+  QgsFeature feature = f;
   if ( feature.hasGeometry() )
   {
     feature.setGeometry( feature.geometry().subdivide( mMaxNodes ) );
@@ -608,7 +611,7 @@ bool QgsSubdivideAlgorithm::processFeature( QgsFeature &feature, QgsProcessingFe
       feedback->reportError( QObject::tr( "Error calculating subdivision for feature %1" ).arg( feature.id() ) );
     }
   }
-  return true;
+  return feature;
 }
 
 bool QgsSubdivideAlgorithm::prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback * )

diff --git a/src/core/processing/qgsnativealgorithms.h b/src/core/processing/qgsnativealgorithms.h
@@ -68,7 +68,7 @@ class QgsCentroidAlgorithm : public QgsProcessingFeatureBasedAlgorithm
     QgsProcessing::LayerType outputLayerType() const override { return QgsProcessing::TypeVectorPoint; }
     QgsWkbTypes::Type outputWkbType( QgsWkbTypes::Type inputWkbType ) const override { Q_UNUSED( inputWkbType ); return QgsWkbTypes::Point; }
 
-    bool processFeature( QgsFeature &feature, QgsProcessingFeedback *feedback ) override;
+    QgsFeature processFeature( const QgsFeature &feature, QgsProcessingFeedback *feedback ) override;
 };
 
 /**
@@ -94,7 +94,7 @@ class QgsTransformAlgorithm : public QgsProcessingFeatureBasedAlgorithm
     QString outputName() const override { return QObject::tr( "Reprojected" ); }
 
     bool prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
-    bool processFeature( QgsFeature &feature, QgsProcessingFeedback *feedback ) override;
+    QgsFeature processFeature( const QgsFeature &feature, QgsProcessingFeedback *feedback ) override;
 
   private:
 
@@ -262,7 +262,7 @@ class QgsSubdivideAlgorithm : public QgsProcessingFeatureBasedAlgorithm
     QString outputName() const override { return QObject::tr( "Subdivided" ); }
 
     QgsWkbTypes::Type outputWkbType( QgsWkbTypes::Type inputWkbType ) const override;
-    bool processFeature( QgsFeature &feature, QgsProcessingFeedback *feedback ) override;
+    QgsFeature processFeature( const QgsFeature &feature, QgsProcessingFeedback *feedback ) override;
 
     bool prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
 

diff --git a/src/core/processing/qgsprocessingalgorithm.cpp b/src/core/processing/qgsprocessingalgorithm.cpp
@@ -655,10 +655,8 @@ QVariantMap QgsProcessingFeatureBasedAlgorithm::processAlgorithm( const QVariant
       break;
     }
 
-    if ( processFeature( f, feedback ) )
-    {
-      sink->addFeature( f, QgsFeatureSink::FastInsert );
-    }
+    QgsFeature transformed = processFeature( f, feedback );
+    sink->addFeature( transformed, QgsFeatureSink::FastInsert );
 
     feedback->setProgress( current * step );
     current++;

diff --git a/src/core/processing/qgsprocessingalgorithm.h b/src/core/processing/qgsprocessingalgorithm.h
@@ -798,8 +798,7 @@ class CORE_EXPORT QgsProcessingFeatureBasedAlgorithm : public QgsProcessingAlgor
      * geometry with the centroid of the original feature geometry for a 'centroid' type
      * algorithm).
      *
-     * Implementations should return true if the feature should be kept and added to the algorithm's
-     * output sink, or false if the feature should be skipped and omitted from the output.
+     * Implementations should return the modified feature.
      *
      * The provided \a feedback object can be used to push messages to the log and for giving feedback
      * to users. Note that handling of progress reports and algorithm cancelation is handled by
@@ -810,7 +809,7 @@ class CORE_EXPORT QgsProcessingFeatureBasedAlgorithm : public QgsProcessingAlgor
      * can break valid model execution - so use with extreme caution, and consider using
      * \a feedback to instead report non-fatal processing failures for features instead.
      */
-    virtual bool processFeature( QgsFeature &feature, QgsProcessingFeedback *feedback ) = 0;
+    virtual QgsFeature processFeature( const QgsFeature &feature, QgsProcessingFeedback *feedback ) = 0;
 
     virtual QVariantMap processAlgorithm( const QVariantMap &parameters,
                                           QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;