QGIS API Documentation  3.17.0-Master (ca637cfeb2)
qgsalgorithmgeometrybyexpression.h
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1 /***************************************************************************
2  qgsalgorithmgeometrybyexpression.h
3  ----------------------
4  begin : November 2019
5  copyright : (C) 2019 by Alexander Bruy
6  email : alexander dot bruy at gmail dot com
7  ***************************************************************************/
8 
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  ***************************************************************************/
17 
18 #ifndef QGSALGORITHMGEOMETRYBYEXPRESSION_H
19 #define QGSALGORITHMGEOMETRYBYEXPRESSION_H
20 
21 #define SIP_NO_FILE
22 
23 #include "qgis_sip.h"
24 #include "qgsprocessingalgorithm.h"
25 #include "qgsapplication.h"
26 
28 
32 class QgsGeometryByExpressionAlgorithm : public QgsProcessingFeatureBasedAlgorithm
33 {
34 
35  public:
36 
37  QgsGeometryByExpressionAlgorithm() = default;
38  QIcon icon() const override { return QgsApplication::getThemeIcon( QStringLiteral( "/algorithms/mAlgorithmCentroids.svg" ) ); }
39  QString svgIconPath() const override { return QgsApplication::iconPath( QStringLiteral( "/algorithms/mAlgorithmCentroids.svg" ) ); }
40  QString name() const override;
41  QString displayName() const override;
42  QStringList tags() const override;
43  QString group() const override;
44  QString groupId() const override;
45  QString shortHelpString() const override;
46  QList<int> inputLayerTypes() const override;
47  QgsGeometryByExpressionAlgorithm *createInstance() const override SIP_FACTORY;
48  void initParameters( const QVariantMap &configuration = QVariantMap() ) override;
49 
50  protected:
51 
52  QString outputName() const override;
55  bool prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
56  QgsFeatureList processFeature( const QgsFeature &feature, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
57 
58  private:
59 
60  QgsWkbTypes::Type mWkbType;
61  QgsExpression mExpression;
62  QgsExpressionContext mExpressionContext;
63 };
64 
66 
67 #endif // QGSALGORITHMGEOMETRYBYEXPRESSION_H
virtual QString outputName() const =0
Returns the translated, user visible name for any layers created by this 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.
virtual QIcon icon() const
Returns an icon for the algorithm.
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.
static QString iconPath(const QString &iconFile)
Returns path to the desired icon file.
static QIcon getThemeIcon(const QString &name)
Helper to get a theme icon.
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.
Type
The WKB type describes the number of dimensions a geometry has.
Definition: qgswkbtypes.h:69
Expression contexts are used to encapsulate the parameters around which a QgsExpression should be eva...
virtual QgsWkbTypes::Type outputWkbType(QgsWkbTypes::Type inputWkbType) const
Maps the input WKB geometry type (inputWkbType) to the corresponding output WKB type generated by the...
#define SIP_FACTORY
Definition: qgis_sip.h:76
virtual QgsProcessingAlgorithm * createInstance() const =0
Creates a new instance of the algorithm class.
Flag
Flags controlling how QgsProcessingFeatureSource fetches features.
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.
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.
virtual QString svgIconPath() const
Returns a path to an SVG version of the algorithm&#39;s icon.