QGIS API Documentation 3.40.0-Bratislava (b56115d8743)
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qgsalgorithmcentroid.cpp
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1/***************************************************************************
2 qgsalgorithmcentroid.cpp
3 ------------------------
4 begin : April 2017
5 copyright : (C) 2017 by Nyall Dawson
6 email : nyall dot dawson 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
20
22
23QString QgsCentroidAlgorithm::name() const
24{
25 return QStringLiteral( "centroids" );
26}
27
28QString QgsCentroidAlgorithm::displayName() const
29{
30 return QObject::tr( "Centroids" );
31}
32
33QStringList QgsCentroidAlgorithm::tags() const
34{
35 return QObject::tr( "centroid,center,average,point,middle" ).split( ',' );
36}
37
38QString QgsCentroidAlgorithm::group() const
39{
40 return QObject::tr( "Vector geometry" );
41}
42
43QString QgsCentroidAlgorithm::groupId() const
44{
45 return QStringLiteral( "vectorgeometry" );
46}
47
48QString QgsCentroidAlgorithm::outputName() const
49{
50 return QObject::tr( "Centroids" );
51}
52
53QgsFeatureSink::SinkFlags QgsCentroidAlgorithm::sinkFlags() const
54{
55 if ( mAllParts )
57 else
59}
60
61QString QgsCentroidAlgorithm::shortHelpString() const
62{
63 return QObject::tr( "This algorithm creates a new point layer, with points representing the centroid of the geometries in an input layer.\n\n"
64 "The attributes associated to each point in the output layer are the same ones associated to the original features." );
65}
66
67Qgis::ProcessingAlgorithmDocumentationFlags QgsCentroidAlgorithm::documentationFlags() const
68{
70}
71
72QgsCentroidAlgorithm *QgsCentroidAlgorithm::createInstance() const
73{
74 return new QgsCentroidAlgorithm();
75}
76
77void QgsCentroidAlgorithm::initParameters( const QVariantMap & )
78{
79 std::unique_ptr< QgsProcessingParameterBoolean> allParts = std::make_unique< QgsProcessingParameterBoolean >(
80 QStringLiteral( "ALL_PARTS" ),
81 QObject::tr( "Create centroid for each part" ),
82 false );
83 allParts->setIsDynamic( true );
84 allParts->setDynamicPropertyDefinition( QgsPropertyDefinition( QStringLiteral( "All parts" ), QObject::tr( "Create centroid for each part" ), QgsPropertyDefinition::Boolean ) );
85 allParts->setDynamicLayerParameterName( QStringLiteral( "INPUT" ) );
86 addParameter( allParts.release() );
87}
88
89bool QgsCentroidAlgorithm::prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback * )
90{
91 mAllParts = parameterAsBoolean( parameters, QStringLiteral( "ALL_PARTS" ), context );
92 mDynamicAllParts = QgsProcessingParameters::isDynamic( parameters, QStringLiteral( "ALL_PARTS" ) );
93 if ( mDynamicAllParts )
94 mAllPartsProperty = parameters.value( QStringLiteral( "ALL_PARTS" ) ).value< QgsProperty >();
95
96 return true;
97}
98
99QgsFeatureList QgsCentroidAlgorithm::processFeature( const QgsFeature &f, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
100{
101 QgsFeatureList list;
102 QgsFeature feature = f;
103 if ( feature.hasGeometry() && !feature.geometry().isEmpty() )
104 {
105 const QgsGeometry geom = feature.geometry();
106
107 bool allParts = mAllParts;
108 if ( mDynamicAllParts )
109 allParts = mAllPartsProperty.valueAsBool( context.expressionContext(), allParts );
110
111 if ( allParts && geom.isMultipart() )
112 {
113 const QgsGeometryCollection *geomCollection = static_cast<const QgsGeometryCollection *>( geom.constGet() );
114
115 const int partCount = geomCollection->partCount();
116 list.reserve( partCount );
117 for ( int i = 0; i < partCount; ++i )
118 {
119 const QgsGeometry partGeometry( geomCollection->geometryN( i )->clone() );
120 const QgsGeometry outputGeometry = partGeometry.centroid();
121 if ( outputGeometry.isNull() )
122 {
123 feedback->reportError( QObject::tr( "Error calculating centroid for feature %1 part %2: %3" ).arg( feature.id() ).arg( i ).arg( outputGeometry.lastError() ) );
124 }
125 feature.setGeometry( outputGeometry );
126 list << feature;
127 }
128 }
129 else
130 {
131 const QgsGeometry outputGeometry = feature.geometry().centroid();
132 if ( outputGeometry.isNull() )
133 {
134 feedback->reportError( QObject::tr( "Error calculating centroid for feature %1: %2" ).arg( feature.id() ).arg( outputGeometry.lastError() ) );
135 }
136 feature.setGeometry( outputGeometry );
137 list << feature;
138 }
139 }
140 else
141 {
142 list << feature;
143 }
144 return list;
145}
146
@ RegeneratesPrimaryKeyInSomeScenarios
Algorithm may drop the existing primary keys or FID values in some scenarios, depending on algorithm ...
QFlags< ProcessingAlgorithmDocumentationFlag > ProcessingAlgorithmDocumentationFlags
Flags describing algorithm behavior for documentation purposes.
Definition qgis.h:3359
virtual QgsAbstractGeometry * clone() const =0
Clones the geometry by performing a deep copy.
QFlags< SinkFlag > SinkFlags
@ RegeneratePrimaryKey
This flag indicates, that a primary key field cannot be guaranteed to be unique and the sink should i...
The feature class encapsulates a single feature including its unique ID, geometry and a list of field...
Definition qgsfeature.h:58
QgsFeatureId id
Definition qgsfeature.h:66
QgsGeometry geometry
Definition qgsfeature.h:69
bool hasGeometry() const
Returns true if the feature has an associated geometry.
void setGeometry(const QgsGeometry &geometry)
Set the feature's geometry.
int partCount() const override
Returns count of parts contained in the geometry.
const QgsAbstractGeometry * geometryN(int n) const
Returns a const reference to a geometry from within the collection.
A geometry is the spatial representation of a feature.
QString lastError() const
Returns an error string referring to the last error encountered either when this geometry was created...
const QgsAbstractGeometry * constGet() const
Returns a non-modifiable (const) reference to the underlying abstract geometry primitive.
bool isMultipart() const
Returns true if WKB of the geometry is of WKBMulti* type.
QgsGeometry centroid() const
Returns the center of mass of a geometry.
bool isEmpty() const
Returns true if the geometry is empty (eg a linestring with no vertices, or a collection with no geom...
Contains information about the context in which a processing algorithm is executed.
QgsExpressionContext & expressionContext()
Returns the expression context.
virtual QgsFeatureSink::SinkFlags sinkFlags() const
Returns the feature sink flags to be used for the output.
Base class for providing feedback from a processing algorithm.
virtual void reportError(const QString &error, bool fatalError=false)
Reports that the algorithm encountered an error while executing.
static bool isDynamic(const QVariantMap &parameters, const QString &name)
Returns true if the parameter with matching name is a dynamic parameter, and must be evaluated once f...
Definition for a property.
Definition qgsproperty.h:45
@ Boolean
Boolean value.
Definition qgsproperty.h:51
A store for object properties.
QList< QgsFeature > QgsFeatureList