QGIS API Documentation  3.17.0-Master (ca637cfeb2)
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1 /***************************************************************************
2  qgsalgorithmfieldcalculator.h
3  ----------------------
4  begin : September 2020
5  copyright : (C) 2020 by Ivan Ivanov
6  email : [email protected]
7  ***************************************************************************/
9 /***************************************************************************
10  * *
11  * This program is free software; you can redistribute it and/or modify *
12  * it under the terms of the GNU General Public License as published by *
13  * the Free Software Foundation; either version 2 of the License, or *
14  * (at your option) any later version. *
15  * *
16  ***************************************************************************/
22 #define SIP_NO_FILE
24 #include "qgis_sip.h"
25 #include "qgsprocessingalgorithm.h"
32 class QgsFieldCalculatorAlgorithm : public QgsProcessingFeatureBasedAlgorithm
33 {
35  public:
37  QgsFieldCalculatorAlgorithm() = default;
38  QString name() const override;
39  QString displayName() const override;
40  QStringList tags() const override;
41  QString group() const override;
42  QString groupId() const override;
43  QString shortHelpString() const override;
44  QList<int> inputLayerTypes() const override;
45  QgsFieldCalculatorAlgorithm *createInstance() const override SIP_FACTORY;
47  protected:
48  void initParameters( const QVariantMap &configuration = QVariantMap() ) override;
49  QString outputName() const override;
50  QgsFields outputFields( const QgsFields &inputFields ) const override;
53  bool prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
54  QgsFeatureList processFeature( const QgsFeature &feature, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
55  bool supportInPlaceEdit( const QgsMapLayer *layer ) const override;
57  private:
58  QgsFields mFields;
59  int mFieldIdx;
60  QgsExpression mExpression;
61  QgsExpressionContext mExpressionContext;
62  QgsDistanceArea mDa;
63  int mRowNumber;
64 };
virtual QString outputName() const =0
Returns the translated, user visible name for any layers created by this algorithm.
virtual QgsFields outputFields(const QgsFields &inputFields) const
Maps the input source fields (inputFields) to corresponding output fields generated by the algorithm...
Class for parsing and evaluation of expressions (formerly called "search strings").
virtual bool prepareAlgorithm(const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback) SIP_THROW(QgsProcessingException)
Prepares the algorithm to run using the specified parameters.
Base class for all map layer types.
Definition: qgsmaplayer.h:83
Base class for providing feedback from a processing algorithm.
virtual QgsFeatureList processFeature(const QgsFeature &feature, QgsProcessingContext &context, QgsProcessingFeedback *feedback) SIP_THROW(QgsProcessingException)=0
Processes an individual input feature from the source.
QList< QgsFeature > QgsFeatureList
Definition: qgsfeature.h:583
virtual QString name() const =0
Returns the algorithm name, used for identifying the algorithm.
virtual QString group() const
Returns the name of the group this algorithm belongs to.
Container of fields for a vector layer.
Definition: qgsfields.h:44
virtual QStringList tags() const
Returns a list of tags which relate to the algorithm, and are used to assist users in searching for s...
The feature class encapsulates a single feature including its id, geometry and a list of field/values...
Definition: qgsfeature.h:55
virtual QList< int > inputLayerTypes() const
Returns the valid input layer types for the source layer for this algorithm.
virtual QString shortHelpString() const
Returns a localised short helper string for the algorithm.
Expression contexts are used to encapsulate the parameters around which a QgsExpression should be eva...
Definition: qgis_sip.h:76
virtual QgsProcessingAlgorithm * createInstance() const =0
Creates a new instance of the algorithm class.
Flags controlling how QgsProcessingFeatureSource fetches features.
A general purpose distance and area calculator, capable of performing ellipsoid based calculations...
virtual QString displayName() const =0
Returns the translated algorithm name, which should be used for any user-visible display of the algor...
virtual QgsProcessingFeatureSource::Flag sourceFlags() const
Returns the processing feature source flags to be used in the algorithm.
bool supportInPlaceEdit(const QgsMapLayer *layer) const override
Checks whether this algorithm supports in-place editing on the given layer Default implementation for...
virtual void initParameters(const QVariantMap &configuration=QVariantMap())
Initializes any extra parameters added by the algorithm subclass.
virtual QString groupId() const
Returns the unique ID of the group this algorithm belongs to.
An abstract QgsProcessingAlgorithm base class for processing algorithms which operate "feature-by-fea...
Contains information about the context in which a processing algorithm is executed.