QGIS API Documentation  3.23.0-Master (dd0cd13a00)
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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"
26 #include "qgsdistancearea.h"
33 class QgsFieldCalculatorAlgorithm : public QgsProcessingFeatureBasedAlgorithm
34 {
36  public:
38  QgsFieldCalculatorAlgorithm() = default;
39  QString name() const override;
40  QString displayName() const override;
41  QStringList tags() const override;
42  QString group() const override;
43  QString groupId() const override;
44  QString shortHelpString() const override;
45  QList<int> inputLayerTypes() const override;
46  QgsFieldCalculatorAlgorithm *createInstance() const override SIP_FACTORY;
48  protected:
49  void initParameters( const QVariantMap &configuration = QVariantMap() ) override;
50  QString outputName() const override;
51  QgsFields outputFields( const QgsFields &inputFields ) const override;
52  QgsProcessingFeatureSource::Flag sourceFlags() const override;
54  bool prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
55  QgsFeatureList processFeature( const QgsFeature &feature, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
56  bool supportInPlaceEdit( const QgsMapLayer *layer ) const override;
58  private:
59  QgsFields mFields;
60  int mFieldIdx;
61  QgsExpression mExpression;
62  QgsExpressionContext mExpressionContext;
63  QgsDistanceArea mDa;
64  int mRowNumber;
65 };
A general purpose distance and area calculator, capable of performing ellipsoid based calculations.
Expression contexts are used to encapsulate the parameters around which a QgsExpression should be eva...
Class for parsing and evaluation of expressions (formerly called "search strings").
The feature class encapsulates a single feature including its unique ID, geometry and a list of field...
Definition: qgsfeature.h:56
Container of fields for a vector layer.
Definition: qgsfields.h:45
Base class for all map layer types.
Definition: qgsmaplayer.h:73
virtual QString group() const
Returns the name of the group this algorithm belongs to.
virtual QString groupId() const
Returns the unique ID of the group this algorithm belongs to.
virtual QString shortHelpString() const
Returns a localised short helper string for the algorithm.
virtual QString displayName() const =0
Returns the translated algorithm name, which should be used for any user-visible display of the algor...
virtual QgsProcessingAlgorithm * createInstance() const =0
Creates a new instance of the algorithm class.
virtual QStringList tags() const
Returns a list of tags which relate to the algorithm, and are used to assist users in searching for s...
virtual QString name() const =0
Returns the algorithm name, used for identifying the algorithm.
Contains information about the context in which a processing algorithm is executed.
An abstract QgsProcessingAlgorithm base class for processing algorithms which operate "feature-by-fea...
virtual QList< int > inputLayerTypes() const
Returns the valid input layer types for the source layer for this algorithm.
Flags controlling how QgsProcessingFeatureSource fetches features.
Base class for providing feedback from a processing algorithm.
Definition: qgis_sip.h:76
QList< QgsFeature > QgsFeatureList
Definition: qgsfeature.h:882