QGIS API Documentation  3.22.4-Białowieża (ce8e65e95e)
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 
18 #include "qgsalgorithmcentroid.h"
19 #include "qgsgeometrycollection.h"
20 
22 
23 QString QgsCentroidAlgorithm::name() const
24 {
25  return QStringLiteral( "centroids" );
26 }
27 
28 QString QgsCentroidAlgorithm::displayName() const
29 {
30  return QObject::tr( "Centroids" );
31 }
32 
33 QStringList QgsCentroidAlgorithm::tags() const
34 {
35  return QObject::tr( "centroid,center,average,point,middle" ).split( ',' );
36 }
37 
38 QString QgsCentroidAlgorithm::group() const
39 {
40  return QObject::tr( "Vector geometry" );
41 }
42 
43 QString QgsCentroidAlgorithm::groupId() const
44 {
45  return QStringLiteral( "vectorgeometry" );
46 }
47 
48 QString QgsCentroidAlgorithm::outputName() const
49 {
50  return QObject::tr( "Centroids" );
51 }
52 
53 QgsFeatureSink::SinkFlags QgsCentroidAlgorithm::sinkFlags() const
54 {
55  if ( mAllParts )
57  else
59 }
60 
61 QString 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 
67 QgsCentroidAlgorithm *QgsCentroidAlgorithm::createInstance() const
68 {
69  return new QgsCentroidAlgorithm();
70 }
71 
72 void QgsCentroidAlgorithm::initParameters( const QVariantMap & )
73 {
74  std::unique_ptr< QgsProcessingParameterBoolean> allParts = std::make_unique< QgsProcessingParameterBoolean >(
75  QStringLiteral( "ALL_PARTS" ),
76  QObject::tr( "Create centroid for each part" ),
77  false );
78  allParts->setIsDynamic( true );
79  allParts->setDynamicPropertyDefinition( QgsPropertyDefinition( QStringLiteral( "All parts" ), QObject::tr( "Create centroid for each part" ), QgsPropertyDefinition::Boolean ) );
80  allParts->setDynamicLayerParameterName( QStringLiteral( "INPUT" ) );
81  addParameter( allParts.release() );
82 }
83 
84 bool QgsCentroidAlgorithm::prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback * )
85 {
86  mAllParts = parameterAsBoolean( parameters, QStringLiteral( "ALL_PARTS" ), context );
87  mDynamicAllParts = QgsProcessingParameters::isDynamic( parameters, QStringLiteral( "ALL_PARTS" ) );
88  if ( mDynamicAllParts )
89  mAllPartsProperty = parameters.value( QStringLiteral( "ALL_PARTS" ) ).value< QgsProperty >();
90 
91  return true;
92 }
93 
94 QgsFeatureList QgsCentroidAlgorithm::processFeature( const QgsFeature &f, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
95 {
96  QgsFeatureList list;
97  QgsFeature feature = f;
98  if ( feature.hasGeometry() && !feature.geometry().isEmpty() )
99  {
100  const QgsGeometry geom = feature.geometry();
101 
102  bool allParts = mAllParts;
103  if ( mDynamicAllParts )
104  allParts = mAllPartsProperty.valueAsBool( context.expressionContext(), allParts );
105 
106  if ( allParts && geom.isMultipart() )
107  {
108  const QgsGeometryCollection *geomCollection = static_cast<const QgsGeometryCollection *>( geom.constGet() );
109 
110  const int partCount = geomCollection->partCount();
111  list.reserve( partCount );
112  for ( int i = 0; i < partCount; ++i )
113  {
114  const QgsGeometry partGeometry( geomCollection->geometryN( i )->clone() );
115  const QgsGeometry outputGeometry = partGeometry.centroid();
116  if ( outputGeometry.isNull() )
117  {
118  feedback->reportError( QObject::tr( "Error calculating centroid for feature %1 part %2: %3" ).arg( feature.id() ).arg( i ).arg( outputGeometry.lastError() ) );
119  }
120  feature.setGeometry( outputGeometry );
121  list << feature;
122  }
123  }
124  else
125  {
126  const QgsGeometry outputGeometry = feature.geometry().centroid();
127  if ( outputGeometry.isNull() )
128  {
129  feedback->reportError( QObject::tr( "Error calculating centroid for feature %1: %2" ).arg( feature.id() ).arg( outputGeometry.lastError() ) );
130  }
131  feature.setGeometry( outputGeometry );
132  list << feature;
133  }
134  }
135  else
136  {
137  list << feature;
138  }
139  return list;
140 }
141 
virtual QgsAbstractGeometry * clone() const =0
Clones the geometry by performing a deep copy.
@ 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:56
QgsGeometry geometry
Definition: qgsfeature.h:67
bool hasGeometry() const
Returns true if the feature has an associated geometry.
Definition: qgsfeature.cpp:223
void setGeometry(const QgsGeometry &geometry)
Set the feature's geometry.
Definition: qgsfeature.cpp:163
Q_GADGET QgsFeatureId id
Definition: qgsfeature.h:64
Geometry collection.
const QgsAbstractGeometry * geometryN(int n) const
Returns a const reference to a geometry from within the collection.
int partCount() const override
Returns count of parts contained in the geometry.
A geometry is the spatial representation of a feature.
Definition: qgsgeometry.h:125
const QgsAbstractGeometry * constGet() const SIP_HOLDGIL
Returns a non-modifiable (const) reference to the underlying abstract geometry primitive.
Q_GADGET bool isNull
Definition: qgsgeometry.h:127
bool isMultipart() const SIP_HOLDGIL
Returns true if WKB of the geometry is of WKBMulti* type.
QgsGeometry centroid() const
Returns the center of mass of a geometry.
QString lastError() const SIP_HOLDGIL
Returns an error string referring to the last error encountered either when this geometry was created...
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:48
@ Boolean
Boolean value.
Definition: qgsproperty.h:54
A store for object properties.
Definition: qgsproperty.h:232
QList< QgsFeature > QgsFeatureList
Definition: qgsfeature.h:882