Port boundary algorithm to c++

Also allow feature based algorithms to customise their appectable
input layers types and set suitable filters for all applicable
algorithms

python/core/processing/qgsprocessingalgorithm.sip

@@ -801,6 +801,14 @@ class QgsProcessingFeatureBasedAlgorithm : QgsProcessingAlgorithm
  :rtype: str
 %End
 
+    virtual QList<int> inputLayerTypes() const;
+%Docstring
+ Returns the valid input layer types for the source layer for this algorithm.
+ By default vector layers with any geometry types (excluding non-spatial, geometryless layers)
+ are accepted.
+ :rtype: list of int
+%End
+
     virtual QgsProcessing::SourceType outputLayerType() const;
 %Docstring
  Returns the layer type for layers generated by this algorithm, if

python/plugins/processing/algs/qgis/AddTableField.py

@@ -27,6 +27,7 @@ __revision__ = '$Format:%H$'
 
 from qgis.PyQt.QtCore import QVariant
 from qgis.core import (QgsField,
+                       QgsProcessing,
                        QgsProcessingParameterString,
                        QgsProcessingParameterNumber,
                        QgsProcessingParameterEnum)
@@ -72,6 +73,9 @@ class AddTableField(QgisFeatureBasedAlgorithm):
     def outputName(self):
         return self.tr('Added')
 
+    def inputLayerTypes(self):
+        return [QgsProcessing.TypeVector]
+
     def prepareAlgorithm(self, parameters, context, feedback):
         field_type = self.parameterAsEnum(parameters, self.FIELD_TYPE, context)
         field_name = self.parameterAsString(parameters, self.FIELD_NAME, context)

python/plugins/processing/algs/qgis/Boundary.py

@@ -1,81 +0,0 @@
-# -*- coding: utf-8 -*-
-
-"""
-***************************************************************************
-    Boundary.py
-    --------------
-    Date                 : July 2016
-    Copyright            : (C) 2016 by Nyall Dawson
-    Email                : nyall dot dawson at gmail dot com
-***************************************************************************
-*                                                                         *
-*   This program is free software; you can redistribute it and/or modify  *
-*   it under the terms of the GNU General Public License as published by  *
-*   the Free Software Foundation; either version 2 of the License, or     *
-*   (at your option) any later version.                                   *
-*                                                                         *
-***************************************************************************
-"""
-
-__author__ = 'Nyall Dawson'
-__date__ = 'July 2016'
-__copyright__ = '(C) 2016, Nyall Dawson'
-
-# This will get replaced with a git SHA1 when you do a git archive323
-
-__revision__ = '$Format:%H$'
-
-import os
-
-from qgis.core import (QgsGeometry,
-                       QgsWkbTypes)
-
-from qgis.PyQt.QtGui import QIcon
-
-from processing.algs.qgis.QgisAlgorithm import QgisFeatureBasedAlgorithm
-
-pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]
-
-
-class Boundary(QgisFeatureBasedAlgorithm):
-
-    def __init__(self):
-        super().__init__()
-
-    def icon(self):
-        return QIcon(os.path.join(pluginPath, 'images', 'ftools', 'convex_hull.png'))
-
-    def group(self):
-        return self.tr('Vector geometry')
-
-    def name(self):
-        return 'boundary'
-
-    def displayName(self):
-        return self.tr('Boundary')
-
-    def outputName(self):
-        return self.tr('Boundary')
-
-    def outputWkbType(self, input_wkb):
-        if QgsWkbTypes.geometryType(input_wkb) == QgsWkbTypes.LineGeometry:
-            output_wkb = QgsWkbTypes.MultiPoint
-        elif QgsWkbTypes.geometryType(input_wkb) == QgsWkbTypes.PolygonGeometry:
-            output_wkb = QgsWkbTypes.MultiLineString
-        if QgsWkbTypes.hasZ(input_wkb):
-            output_wkb = QgsWkbTypes.addZ(output_wkb)
-        if QgsWkbTypes.hasM(input_wkb):
-            output_wkb = QgsWkbTypes.addM(output_wkb)
-
-        return output_wkb
-
-    def processFeature(self, feature, feedback):
-        input_geometry = feature.geometry()
-        if input_geometry:
-            output_geometry = QgsGeometry(input_geometry.geometry().boundary())
-            if not output_geometry:
-                feedback.reportError(self.tr('No boundary for feature {} (possibly a closed linestring?)').format(feature.id()))
-                feature.clearGeometry()
-            else:
-                feature.setGeometry(output_geometry)
-        return feature

python/plugins/processing/algs/qgis/DeleteColumn.py

@@ -25,7 +25,8 @@ __copyright__ = '(C) 2010, Michael Minn'
 
 __revision__ = '$Format:%H$'
 
-from qgis.core import (QgsProcessingParameterField)
+from qgis.core import (QgsProcessingParameterField,
+                       QgsProcessing)
 from processing.algs.qgis.QgisAlgorithm import QgisFeatureBasedAlgorithm
 
 
@@ -49,6 +50,9 @@ class DeleteColumn(QgisFeatureBasedAlgorithm):
                                                       self.tr('Fields to drop'),
                                                       None, 'INPUT', QgsProcessingParameterField.Any, True))
 
+    def inputLayerTypes(self):
+        return [QgsProcessing.TypeVector]
+
     def name(self):
         return 'deletecolumn'
 

python/plugins/processing/algs/qgis/DeleteHoles.py

@@ -24,7 +24,8 @@ __copyright__ = '(C) 2015, Etienne Trimaille'
 
 __revision__ = '$Format:%H$'
 
-from qgis.core import (QgsProcessingParameterNumber)
+from qgis.core import (QgsProcessingParameterNumber,
+                       QgsProcessing)
 from processing.algs.qgis.QgisAlgorithm import QgisFeatureBasedAlgorithm
 
 
@@ -56,6 +57,9 @@ class DeleteHoles(QgisFeatureBasedAlgorithm):
     def outputName(self):
         return self.tr('Cleaned')
 
+    def inputLayerTypes(self):
+        return [QgsProcessing.TypeVectorPolygon]
+
     def prepareAlgorithm(self, parameters, context, feedback):
         self.min_area = self.parameterAsDouble(parameters, self.MIN_AREA, context)
         if self.min_area == 0.0:

python/plugins/processing/algs/qgis/DensifyGeometries.py

@@ -28,7 +28,8 @@ __revision__ = '$Format:%H$'
 
 import os
 
-from qgis.core import (QgsProcessingParameterNumber)
+from qgis.core import (QgsProcessingParameterNumber,
+                       QgsProcessing)
 
 from processing.algs.qgis.QgisAlgorithm import QgisFeatureBasedAlgorithm
 
@@ -61,6 +62,9 @@ class DensifyGeometries(QgisFeatureBasedAlgorithm):
     def outputName(self):
         return self.tr('Densified')
 
+    def inputLayerTypes(self):
+        return [QgsProcessing.TypeVectorLine, QgsProcessing.TypeVectorPolygon]
+
     def prepareAlgorithm(self, parameters, context, feedback):
         self.vertices = self.parameterAsInt(parameters, self.VERTICES, context)
         return True

python/plugins/processing/algs/qgis/DensifyGeometriesInterval.py

@@ -27,7 +27,8 @@ __copyright__ = '(C) 2012, Anita Graser'
 
 __revision__ = '$Format:%H$'
 
-from qgis.core import (QgsProcessingParameterNumber)
+from qgis.core import (QgsProcessingParameterNumber,
+                       QgsProcessing)
 
 from processing.algs.qgis.QgisAlgorithm import QgisFeatureBasedAlgorithm
 
@@ -57,6 +58,9 @@ class DensifyGeometriesInterval(QgisFeatureBasedAlgorithm):
     def outputName(self):
         return self.tr('Densified')
 
+    def inputLayerTypes(self):
+        return [QgsProcessing.TypeVectorLine, QgsProcessing.TypeVectorPolygon]
+
     def prepareAlgorithm(self, parameters, context, feedback):
         interval = self.parameterAsDouble(parameters, self.INTERVAL, context)
         return True

python/plugins/processing/algs/qgis/ExtendLines.py

@@ -26,7 +26,8 @@ __copyright__ = '(C) 2016, Nyall Dawson'
 __revision__ = '$Format:%H$'
 
 from qgis.core import (QgsProcessingParameterNumber,
-                       QgsProcessingException)
+                       QgsProcessingException,
+                       QgsProcessing)
 from processing.algs.qgis.QgisAlgorithm import QgisFeatureBasedAlgorithm
 
 
@@ -58,6 +59,9 @@ class ExtendLines(QgisFeatureBasedAlgorithm):
     def outputName(self):
         return self.tr('Extended')
 
+    def inputLayerTypes(self):
+        return [QgsProcessing.TypeVectorLine]
+
     def prepareAlgorithm(self, parameters, context, feedback):
         self.start_distance = self.parameterAsDouble(parameters, self.START_DISTANCE, context)
         self.end_distance = self.parameterAsDouble(parameters, self.END_DISTANCE, context)

python/plugins/processing/algs/qgis/FieldsMapper.py

@@ -30,6 +30,7 @@ from qgis.core import (
     QgsExpression,
     QgsField,
     QgsFields,
+    QgsProcessing,
     QgsProcessingException,
     QgsProcessingParameterDefinition)
 
@@ -103,6 +104,9 @@ class FieldsMapper(QgisFeatureBasedAlgorithm):
     def outputName(self):
         return self.tr('Refactored')
 
+    def inputLayerTypes(self):
+        return [QgsProcessing.TypeVector]
+
     def parameterAsFieldsMapping(self, parameters, name, context):
         return parameters[name]
 

python/plugins/processing/algs/qgis/LinesToPolygons.py

@@ -74,6 +74,9 @@ class LinesToPolygons(QgisFeatureBasedAlgorithm):
     def outputType(self):
         return QgsProcessing.TypeVectorPolygon
 
+    def inputLayerTypes(self):
+        return [QgsProcessing.TypeVectorLine]
+
     def outputWkbType(self, input_wkb_type):
         return self.convertWkbToPolygons(input_wkb_type)
 

python/plugins/processing/algs/qgis/OffsetLine.py

@@ -87,6 +87,9 @@ class OffsetLine(QgisFeatureBasedAlgorithm):
     def outputName(self):
         return self.tr('Offset')
 
+    def inputLayerTypes(self):
+        return [QgsProcessing.TypeVectorLine]
+
     def outputType(self):
         return QgsProcessing.TypeVectorLine
 

python/plugins/processing/algs/qgis/Orthogonalize.py

@@ -25,7 +25,8 @@ __copyright__ = '(C) 2016, Nyall Dawson'
 
 __revision__ = '$Format:%H$'
 
-from qgis.core import (QgsProcessingException,
+from qgis.core import (QgsProcessing,
+                       QgsProcessingException,
                        QgsProcessingParameterDefinition,
                        QgsProcessingParameterNumber)
 from processing.algs.qgis.QgisAlgorithm import QgisFeatureBasedAlgorithm
@@ -70,6 +71,9 @@ class Orthogonalize(QgisFeatureBasedAlgorithm):
     def outputName(self):
         return self.tr('Orthogonalized')
 
+    def inputLayerTypes(self):
+        return [QgsProcessing.TypeVectorPolygon, QgsProcessing.TypeVectorLine]
+
     def prepareAlgorithm(self, parameters, context, feedback):
         self.max_iterations = self.parameterAsInt(parameters, self.MAX_ITERATIONS, context)
         self.angle_tolerance = self.parameterAsDouble(parameters, self.ANGLE_TOLERANCE, context)

python/plugins/processing/algs/qgis/PolygonsToLines.py

@@ -67,6 +67,9 @@ class PolygonsToLines(QgisFeatureBasedAlgorithm):
     def outputType(self):
         return QgsProcessing.TypeVectorLine
 
+    def inputLayerTypes(self):
+        return [QgsProcessing.TypeVectorPolygon]
+
     def outputWkbType(self, input_wkb_type):
         return self.convertWkbToLines(input_wkb_type)
 

python/plugins/processing/algs/qgis/QGISAlgorithmProvider.py

@@ -44,7 +44,6 @@ from .AddTableField import AddTableField
 from .Aggregate import Aggregate
 from .Aspect import Aspect
 from .BasicStatistics import BasicStatisticsForField
-from .Boundary import Boundary
 from .CheckValidity import CheckValidity
 from .ConcaveHull import ConcaveHull
 from .CreateAttributeIndex import CreateAttributeIndex
@@ -174,7 +173,6 @@ class QGISAlgorithmProvider(QgsProcessingProvider):
                 Aggregate(),
                 Aspect(),
                 BasicStatisticsForField(),
-                Boundary(),
                 CheckValidity(),
                 ConcaveHull(),
                 CreateAttributeIndex(),

python/plugins/processing/algs/qgis/ReverseLineDirection.py

@@ -51,6 +51,9 @@ class ReverseLineDirection(QgisFeatureBasedAlgorithm):
     def outputType(self):
         return QgsProcessing.TypeVectorLine
 
+    def inputLayerTypes(self):
+        return [QgsProcessing.TypeVectorLine]
+
     def processFeature(self, feature, feedback):
         if feature.geometry():
             inGeom = feature.geometry()

python/plugins/processing/algs/qgis/SingleSidedBuffer.py

@@ -86,6 +86,9 @@ class SingleSidedBuffer(QgisFeatureBasedAlgorithm):
     def outputName(self):
         return self.tr('Buffers')
 
+    def inputLayerTypes(self):
+        return [QgsProcessing.TypeVectorLine]
+
     def outputType(self):
         return QgsProcessing.TypeVectorPolygon
 

python/plugins/processing/algs/qgis/TextToFloat.py

@@ -27,6 +27,7 @@ __revision__ = '$Format:%H$'
 
 from qgis.PyQt.QtCore import QVariant
 from qgis.core import (QgsField,
+                       QgsProcessing,
                        QgsProcessingParameterField)
 from processing.algs.qgis.QgisAlgorithm import QgisFeatureBasedAlgorithm
 
@@ -59,6 +60,9 @@ class TextToFloat(QgisFeatureBasedAlgorithm):
     def outputName(self):
         return self.tr('Float from text')
 
+    def inputLayerTypes(self):
+        return [QgsProcessing.TypeVector]
+
     def outputFields(self, inputFields):
         self.field_idx = inputFields.lookupField(self.field_name)
         if self.field_idx >= 0:

python/plugins/processing/tests/testdata/qgis_algorithm_tests.yaml

@@ -665,7 +665,7 @@ tests:
         name: expected/multipoint_bounds.gml
         type: vector
 
-  - algorithm: qgis:boundary
+  - algorithm: native:boundary
     name: Polygon boundary
     params:
       INPUT:
@@ -676,7 +676,7 @@ tests:
         name: expected/poly_boundary.gml
         type: vector
 
-  - algorithm: qgis:boundary
+  - algorithm: native:boundary
     name: Multipoly boundary
     params:
       INPUT:
@@ -687,7 +687,7 @@ tests:
         name: expected/multipoly_boundary.gml
         type: vector
 
-  - algorithm: qgis:boundary
+  - algorithm: native:boundary
     name: Line boundary
     params:
       INPUT:
@@ -698,7 +698,7 @@ tests:
         name: expected/lines_boundary.gml
         type: vector
 
-  - algorithm: qgis:boundary
+  - algorithm: native:boundary
     name: Multiline boundary
     params:
       INPUT:

src/core/processing/qgsnativealgorithms.cpp

@@ -94,6 +94,7 @@ void QgsNativeAlgorithms::loadAlgorithms()
   addAlgorithm( new QgsJoinWithLinesAlgorithm() );
   addAlgorithm( new QgsAssignProjectionAlgorithm() );
   addAlgorithm( new QgsAddIncrementalFieldAlgorithm() );
+  addAlgorithm( new QgsBoundaryAlgorithm() );
 }
 
 void QgsSaveSelectedFeatures::initAlgorithm( const QVariantMap & )
@@ -707,6 +708,11 @@ QString QgsAddIncrementalFieldAlgorithm::shortHelpString() const
                       "The initial starting value for the incremental series can be specified." );
 }
 
+QList<int> QgsAddIncrementalFieldAlgorithm::inputLayerTypes() const
+{
+  return QList<int>() << QgsProcessing::TypeVector;
+}
+
 QgsAddIncrementalFieldAlgorithm *QgsAddIncrementalFieldAlgorithm::createInstance() const
 {
   return new QgsAddIncrementalFieldAlgorithm();
@@ -1834,6 +1840,11 @@ QString QgsMergeLinesAlgorithm::shortHelpString() const
                       "geometry will be a MultiLineString containing any lines which could be merged and any non-connected line parts." );
 }
 
+QList<int> QgsMergeLinesAlgorithm::inputLayerTypes() const
+{
+  return QList<int>() << QgsProcessing::TypeVectorLine;
+}
+
 QgsMergeLinesAlgorithm *QgsMergeLinesAlgorithm::createInstance() const
 {
   return new QgsMergeLinesAlgorithm();
@@ -1874,6 +1885,11 @@ QgsSmoothAlgorithm *QgsSmoothAlgorithm::createInstance() const
   return new QgsSmoothAlgorithm();
 }
 
+QList<int> QgsSmoothAlgorithm::inputLayerTypes() const
+{
+  return QList<int>() << QgsProcessing::TypeVectorLine << QgsProcessing::TypeVectorPolygon;
+}
+
 void QgsSmoothAlgorithm::initParameters( const QVariantMap & )
 {
   addParameter( new QgsProcessingParameterNumber( QStringLiteral( "ITERATIONS" ),
@@ -1923,6 +1939,11 @@ QgsSimplifyAlgorithm *QgsSimplifyAlgorithm::createInstance() const
   return new QgsSimplifyAlgorithm();
 }
 
+QList<int> QgsSimplifyAlgorithm::inputLayerTypes() const
+{
+  return QList<int>() << QgsProcessing::TypeVectorLine << QgsProcessing::TypeVectorPolygon;
+}
+
 void QgsSimplifyAlgorithm::initParameters( const QVariantMap & )
 {
   QStringList methods;
@@ -3174,5 +3195,72 @@ QVariantMap QgsJoinWithLinesAlgorithm::processAlgorithm( const QVariantMap &para
   return outputs;
 }
 
+QString QgsBoundaryAlgorithm::shortHelpString() const
+{
+  return QObject::tr( "Returns the closure of the combinatorial boundary of the input geometries (ie the "
+                      "topological boundary of the geometry). For instance, a polygon geometry will have a "
+                      "boundary consisting of the linestrings for each ring in the polygon. Only valid for "
+                      "polygon or line layers." );
+}
+
+QList<int> QgsBoundaryAlgorithm::inputLayerTypes() const
+{
+  return QList<int>() << QgsProcessing::TypeVectorLine << QgsProcessing::TypeVectorPolygon;
+}
+
+QgsBoundaryAlgorithm *QgsBoundaryAlgorithm::createInstance() const
+{
+  return new QgsBoundaryAlgorithm();
+}
+
+QgsWkbTypes::Type QgsBoundaryAlgorithm::outputWkbType( QgsWkbTypes::Type inputWkbType ) const
+{
+  QgsWkbTypes::Type outputWkb = QgsWkbTypes::Unknown;
+  switch ( QgsWkbTypes::geometryType( inputWkbType ) )
+  {
+    case QgsWkbTypes::LineGeometry:
+      outputWkb = QgsWkbTypes::MultiPoint;
+      break;
+
+    case QgsWkbTypes::PolygonGeometry:
+      outputWkb = QgsWkbTypes::MultiLineString;
+      break;
+
+    case QgsWkbTypes::PointGeometry:
+    case QgsWkbTypes::UnknownGeometry:
+    case QgsWkbTypes::NoGeometry:
+      outputWkb = QgsWkbTypes::NoGeometry;
+      break;
+  }
+
+  if ( QgsWkbTypes::hasZ( inputWkbType ) )
+    outputWkb = QgsWkbTypes::addZ( outputWkb );
+  if ( QgsWkbTypes::hasM( inputWkbType ) )
+    outputWkb = QgsWkbTypes::addM( outputWkb );
+
+  return outputWkb;
+}
+
+QgsFeature QgsBoundaryAlgorithm::processFeature( const QgsFeature &feature, QgsProcessingFeedback *feedback )
+{
+  QgsFeature outFeature = feature;
+
+  if ( feature.hasGeometry() )
+  {
+    QgsGeometry inputGeometry = feature.geometry();
+    QgsGeometry outputGeometry = QgsGeometry( inputGeometry.geometry()->boundary() );
+    if ( !outputGeometry )
+    {
+      feedback->reportError( QObject::tr( "No boundary for feature %1 (possibly a closed linestring?)'" ).arg( feature.id() ) );
+      outFeature.clearGeometry();
+    }
+    else
+    {
+      outFeature.setGeometry( outputGeometry );
+    }
+  }
+  return outFeature;
+}
+
 
 ///@endcond

src/core/processing/qgsnativealgorithms.h

@@ -98,6 +98,30 @@ class QgsCentroidAlgorithm : public QgsProcessingFeatureBasedAlgorithm
     QgsFeature processFeature( const QgsFeature &feature, QgsProcessingFeedback *feedback ) override;
 };
 
+/**
+ * Native boundary algorithm.
+ */
+class QgsBoundaryAlgorithm : public QgsProcessingFeatureBasedAlgorithm
+{
+
+  public:
+
+    QgsBoundaryAlgorithm() = default;
+    QString name() const override { return QStringLiteral( "boundary" ); }
+    QString displayName() const override { return QObject::tr( "Boundary" ); }
+    QStringList tags() const override { return QObject::tr( "boundary,ring,border,exterior" ).split( ',' ); }
+    QString group() const override { return QObject::tr( "Vector geometry" ); }
+    QString shortHelpString() const override;
+    QList<int> inputLayerTypes() const override;
+    QgsBoundaryAlgorithm *createInstance() const override SIP_FACTORY;
+
+  protected:
+
+    QString outputName() const override { return QObject::tr( "Boundary" ); }
+    QgsWkbTypes::Type outputWkbType( QgsWkbTypes::Type inputWkbType ) const override;
+    QgsFeature processFeature( const QgsFeature &feature, QgsProcessingFeedback *feedback ) override;
+};
+
 /**
  * Native transform algorithm.
  */
@@ -179,6 +203,7 @@ class QgsAddIncrementalFieldAlgorithm : public QgsProcessingFeatureBasedAlgorith
     virtual QStringList tags() const override { return QObject::tr( "add,create,serial,primary,key,unique,field" ).split( ',' ); }
     QString group() const override { return QObject::tr( "Vector table" ); }
     QString shortHelpString() const override;
+    QList<int> inputLayerTypes() const override;
     QgsAddIncrementalFieldAlgorithm *createInstance() const override SIP_FACTORY;
 
   protected:
@@ -686,6 +711,7 @@ class QgsMergeLinesAlgorithm : public QgsProcessingFeatureBasedAlgorithm
     virtual QStringList tags() const override { return QObject::tr( "line,merge,join,parts" ).split( ',' ); }
     QString group() const override { return QObject::tr( "Vector geometry" ); }
     QString shortHelpString() const override;
+    QList<int> inputLayerTypes() const override;
     QgsMergeLinesAlgorithm *createInstance() const override SIP_FACTORY;
 
   protected:
@@ -711,6 +737,7 @@ class QgsSmoothAlgorithm : public QgsProcessingFeatureBasedAlgorithm
     QString group() const override { return QObject::tr( "Vector geometry" ); }
     QString shortHelpString() const override;
     QgsSmoothAlgorithm *createInstance() const override SIP_FACTORY;
+    QList<int> inputLayerTypes() const override;
     void initParameters( const QVariantMap &configuration = QVariantMap() ) override;
 
   protected:
@@ -740,6 +767,7 @@ class QgsSimplifyAlgorithm : public QgsProcessingFeatureBasedAlgorithm
     QString group() const override { return QObject::tr( "Vector geometry" ); }
     QString shortHelpString() const override;
     QgsSimplifyAlgorithm *createInstance() const override SIP_FACTORY;
+    QList<int> inputLayerTypes() const override;
     void initParameters( const QVariantMap &configuration = QVariantMap() ) override;
 
   protected:

src/core/processing/qgsprocessingalgorithm.cpp

@@ -629,11 +629,45 @@ bool QgsProcessingAlgorithm::createAutoOutputForParameter( QgsProcessingParamete
 
 void QgsProcessingFeatureBasedAlgorithm::initAlgorithm( const QVariantMap &config )
 {
-  addParameter( new QgsProcessingParameterFeatureSource( QStringLiteral( "INPUT" ), QObject::tr( "Input layer" ) ) );
+  addParameter( new QgsProcessingParameterFeatureSource( QStringLiteral( "INPUT" ), QObject::tr( "Input layer" ), inputLayerTypes() ) );
   initParameters( config );
   addParameter( new QgsProcessingParameterFeatureSink( QStringLiteral( "OUTPUT" ), outputName(), outputLayerType() ) );
 }
 
+QList<int> QgsProcessingFeatureBasedAlgorithm::inputLayerTypes() const
+{
+  return QList<int>();
+}
+
+QgsProcessing::SourceType QgsProcessingFeatureBasedAlgorithm::outputLayerType() const
+{
+  return QgsProcessing::TypeVectorAnyGeometry;
+}
+
+QgsProcessingFeatureSource::Flag QgsProcessingFeatureBasedAlgorithm::sourceFlags() const
+{
+  return static_cast<QgsProcessingFeatureSource::Flag>( 0 );
+}
+
+QgsWkbTypes::Type QgsProcessingFeatureBasedAlgorithm::outputWkbType( QgsWkbTypes::Type inputWkbType ) const
+{
+  return inputWkbType;
+}
+
+QgsFields QgsProcessingFeatureBasedAlgorithm::outputFields( const QgsFields &inputFields ) const
+{
+  return inputFields;
+}
+
+QgsCoordinateReferenceSystem QgsProcessingFeatureBasedAlgorithm::outputCrs( const QgsCoordinateReferenceSystem &inputCrs ) const
+{
+  return inputCrs;
+}
+
+void QgsProcessingFeatureBasedAlgorithm::initParameters( const QVariantMap & )
+{
+}
+
 QgsCoordinateReferenceSystem QgsProcessingFeatureBasedAlgorithm::sourceCrs() const
 {
   if ( mSource )

src/core/processing/qgsprocessingalgorithm.h

@@ -790,16 +790,23 @@ class CORE_EXPORT QgsProcessingFeatureBasedAlgorithm : public QgsProcessingAlgor
      */
     virtual QString outputName() const = 0;
 
+    /**
+     * Returns the valid input layer types for the source layer for this algorithm.
+     * By default vector layers with any geometry types (excluding non-spatial, geometryless layers)
+     * are accepted.
+     */
+    virtual QList<int> inputLayerTypes() const;
+
     /**
      * Returns the layer type for layers generated by this algorithm, if
      * this is possible to determine in advance.
      */
-    virtual QgsProcessing::SourceType outputLayerType() const { return QgsProcessing::TypeVectorAnyGeometry; }
+    virtual QgsProcessing::SourceType outputLayerType() const;
 
     /**
      * Returns the processing feature source flags to be used in the algorithm.
      */
-    virtual QgsProcessingFeatureSource::Flag sourceFlags() const { return static_cast<QgsProcessingFeatureSource::Flag>( 0 ); }
+    virtual QgsProcessingFeatureSource::Flag sourceFlags() const;
 
     /**
      * Maps the input WKB geometry type (\a inputWkbType) to the corresponding
@@ -808,7 +815,7 @@ class CORE_EXPORT QgsProcessingFeatureBasedAlgorithm : public QgsProcessingAlgor
      * This is called once by the base class when creating the output sink for the algorithm (i.e. it is
      * not called once per feature processed).
      */
-    virtual QgsWkbTypes::Type outputWkbType( QgsWkbTypes::Type inputWkbType ) const { return inputWkbType; }
+    virtual QgsWkbTypes::Type outputWkbType( QgsWkbTypes::Type inputWkbType ) const;
 
     /**
      * Maps the input source fields (\a inputFields) to corresponding
@@ -820,7 +827,7 @@ class CORE_EXPORT QgsProcessingFeatureBasedAlgorithm : public QgsProcessingAlgor
      * This is called once by the base class when creating the output sink for the algorithm (i.e. it is
      * not called once per feature processed).
      */
-    virtual QgsFields outputFields( const QgsFields &inputFields ) const { return inputFields; }
+    virtual QgsFields outputFields( const QgsFields &inputFields ) const;
 
     /**
      * Maps the input source coordinate reference system (\a inputCrs) to a corresponding
@@ -830,14 +837,14 @@ class CORE_EXPORT QgsProcessingFeatureBasedAlgorithm : public QgsProcessingAlgor
      * This is called once by the base class when creating the output sink for the algorithm (i.e. it is
      * not called once per feature processed).
      */
-    virtual QgsCoordinateReferenceSystem outputCrs( const QgsCoordinateReferenceSystem &inputCrs ) const { return inputCrs; }
+    virtual QgsCoordinateReferenceSystem outputCrs( const QgsCoordinateReferenceSystem &inputCrs ) const;
 
     /**
      * Initializes any extra parameters added by the algorithm subclass. There is no need
      * to declare the input source or output sink, as these are automatically created by
      * QgsProcessingFeatureBasedAlgorithm.
      */
-    virtual void initParameters( const QVariantMap &configuration = QVariantMap() ) { Q_UNUSED( configuration ); }
+    virtual void initParameters( const QVariantMap &configuration = QVariantMap() );
 
     /**
      * Returns the source's coordinate reference system. This will only return a valid CRS when