[processing] Simplify algorithm should not run validity checks on geometries

Simplify (by its intrinsic nature) can output invalid geometries,
and its processing is not affected by the presence of input
geometry validity.

Also tag a few other algorithms which aren't sensitive to input
geometry validity.

(cherry picked from commit 9b6367f)

Author: nyalldawson

src/analysis/processing/qgsalgorithmsimplify.cpp

@@ -132,6 +132,11 @@ QgsFeatureList QgsSimplifyAlgorithm::processFeature( const QgsFeature &feature,
   return QgsFeatureList() << f;
 }
 
+QgsProcessingFeatureSource::Flag QgsSimplifyAlgorithm::sourceFlags() const
+{
+  return QgsProcessingFeatureSource::FlagSkipGeometryValidityChecks;
+}
+
 ///@endcond
 
 

src/analysis/processing/qgsalgorithmsimplify.h

@@ -51,7 +51,7 @@ class QgsSimplifyAlgorithm : public QgsProcessingFeatureBasedAlgorithm
     QString outputName() const override;
     bool prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
     QgsFeatureList processFeature( const QgsFeature &feature,  QgsProcessingContext &, QgsProcessingFeedback *feedback ) override;
-
+    QgsProcessingFeatureSource::Flag sourceFlags() const override;
   private:
 
     double mTolerance = 1.0;

src/analysis/processing/qgsalgorithmsmooth.cpp

@@ -156,6 +156,11 @@ QgsFeatureList QgsSmoothAlgorithm::processFeature( const QgsFeature &feature, Qg
   return QgsFeatureList() << f;
 }
 
+QgsProcessingFeatureSource::Flag QgsSmoothAlgorithm::sourceFlags() const
+{
+  return QgsProcessingFeatureSource::FlagSkipGeometryValidityChecks;
+}
+
 ///@endcond
 
 

src/analysis/processing/qgsalgorithmsmooth.h

@@ -49,6 +49,7 @@ class QgsSmoothAlgorithm : public QgsProcessingFeatureBasedAlgorithm
     QgsProcessing::SourceType outputLayerType() const override;
     bool prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
     QgsFeatureList processFeature( const QgsFeature &feature,  QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
+    QgsProcessingFeatureSource::Flag sourceFlags() const override;
 
   private:
     int mIterations = 1;

src/analysis/processing/qgsalgorithmsnaptogrid.cpp

@@ -154,6 +154,11 @@ QgsFeatureList QgsSnapToGridAlgorithm::processFeature( const QgsFeature &feature
   return QgsFeatureList() << f;
 }
 
+QgsProcessingFeatureSource::Flag QgsSnapToGridAlgorithm::sourceFlags() const
+{
+  return QgsProcessingFeatureSource::FlagSkipGeometryValidityChecks;
+}
+
 ///@endcond
 
 

src/analysis/processing/qgsalgorithmsnaptogrid.h

@@ -47,6 +47,7 @@ class QgsSnapToGridAlgorithm : public QgsProcessingFeatureBasedAlgorithm
     QString outputName() const override;
     bool prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
     QgsFeatureList processFeature( const QgsFeature &feature,  QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
+    QgsProcessingFeatureSource::Flag sourceFlags() const override;
 
   private:
     double mIntervalX = 0.0;