QGIS API Documentation  3.26.3-Buenos Aires (65e4edfdad)
qgsalgorithmintersection.cpp
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1 /***************************************************************************
2  qgsalgorithmintersection.cpp
3  ---------------------
4  Date : April 2018
5  Copyright : (C) 2018 by Martin Dobias
6  Email : wonder dot sk at gmail dot com
7  ***************************************************************************
8  * *
9  * This program is free software; you can redistribute it and/or modify *
10  * it under the terms of the GNU General Public License as published by *
11  * the Free Software Foundation; either version 2 of the License, or *
12  * (at your option) any later version. *
13  * *
14  ***************************************************************************/
15 
17 
18 #include "qgsgeometrycollection.h"
19 #include "qgsgeometryengine.h"
20 #include "qgsoverlayutils.h"
21 
23 
24 
25 QString QgsIntersectionAlgorithm::name() const
26 {
27  return QStringLiteral( "intersection" );
28 }
29 
30 QString QgsIntersectionAlgorithm::displayName() const
31 {
32  return QObject::tr( "Intersection" );
33 }
34 
35 QString QgsIntersectionAlgorithm::group() const
36 {
37  return QObject::tr( "Vector overlay" );
38 }
39 
40 QString QgsIntersectionAlgorithm::groupId() const
41 {
42  return QStringLiteral( "vectoroverlay" );
43 }
44 
45 QString QgsIntersectionAlgorithm::shortHelpString() const
46 {
47  return QObject::tr( "This algorithm extracts the overlapping portions of features in the Input and Overlay layers. "
48  "Features in the output Intersection layer are assigned the attributes of the overlapping features "
49  "from both the Input and Overlay layers." );
50 }
51 
52 QgsProcessingAlgorithm *QgsIntersectionAlgorithm::createInstance() const
53 {
54  return new QgsIntersectionAlgorithm();
55 }
56 
57 void QgsIntersectionAlgorithm::initAlgorithm( const QVariantMap & )
58 {
59  addParameter( new QgsProcessingParameterFeatureSource( QStringLiteral( "INPUT" ), QObject::tr( "Input layer" ) ) );
60  addParameter( new QgsProcessingParameterFeatureSource( QStringLiteral( "OVERLAY" ), QObject::tr( "Overlay layer" ) ) );
61 
62  addParameter( new QgsProcessingParameterField(
63  QStringLiteral( "INPUT_FIELDS" ),
64  QObject::tr( "Input fields to keep (leave empty to keep all fields)" ), QVariant(),
65  QStringLiteral( "INPUT" ), QgsProcessingParameterField::Any, true, true ) );
66  addParameter( new QgsProcessingParameterField(
67  QStringLiteral( "OVERLAY_FIELDS" ),
68  QObject::tr( "Overlay fields to keep (leave empty to keep all fields)" ), QVariant(),
69  QStringLiteral( "OVERLAY" ), QgsProcessingParameterField::Any, true, true ) );
70 
71  std::unique_ptr< QgsProcessingParameterString > prefix = std::make_unique< QgsProcessingParameterString >( QStringLiteral( "OVERLAY_FIELDS_PREFIX" ), QObject::tr( "Overlay fields prefix" ), QString(), false, true );
72  prefix->setFlags( prefix->flags() | QgsProcessingParameterDefinition::FlagAdvanced );
73  addParameter( prefix.release() );
74 
75  addParameter( new QgsProcessingParameterFeatureSink( QStringLiteral( "OUTPUT" ), QObject::tr( "Intersection" ) ) );
76 
77 }
78 
79 
80 QVariantMap QgsIntersectionAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
81 {
82  std::unique_ptr< QgsFeatureSource > sourceA( parameterAsSource( parameters, QStringLiteral( "INPUT" ), context ) );
83  if ( !sourceA )
84  throw QgsProcessingException( invalidSourceError( parameters, QStringLiteral( "INPUT" ) ) );
85 
86  std::unique_ptr< QgsFeatureSource > sourceB( parameterAsSource( parameters, QStringLiteral( "OVERLAY" ), context ) );
87  if ( !sourceB )
88  throw QgsProcessingException( invalidSourceError( parameters, QStringLiteral( "OVERLAY" ) ) );
89 
90  const QgsWkbTypes::Type geomType = QgsWkbTypes::multiType( sourceA->wkbType() );
91 
92  const QStringList fieldsA = parameterAsFields( parameters, QStringLiteral( "INPUT_FIELDS" ), context );
93  const QStringList fieldsB = parameterAsFields( parameters, QStringLiteral( "OVERLAY_FIELDS" ), context );
94 
95  const QList<int> fieldIndicesA = QgsProcessingUtils::fieldNamesToIndices( fieldsA, sourceA->fields() );
96  const QList<int> fieldIndicesB = QgsProcessingUtils::fieldNamesToIndices( fieldsB, sourceB->fields() );
97 
98  const QString overlayFieldsPrefix = parameterAsString( parameters, QStringLiteral( "OVERLAY_FIELDS_PREFIX" ), context );
99  const QgsFields outputFields = QgsProcessingUtils::combineFields(
100  QgsProcessingUtils::indicesToFields( fieldIndicesA, sourceA->fields() ),
101  QgsProcessingUtils::indicesToFields( fieldIndicesB, sourceB->fields() ),
102  overlayFieldsPrefix );
103 
104  QString dest;
105  std::unique_ptr< QgsFeatureSink > sink( parameterAsSink( parameters, QStringLiteral( "OUTPUT" ), context, dest, outputFields, geomType, sourceA->sourceCrs(), QgsFeatureSink::RegeneratePrimaryKey ) );
106  if ( !sink )
107  throw QgsProcessingException( invalidSinkError( parameters, QStringLiteral( "OUTPUT" ) ) );
108 
109  QVariantMap outputs;
110  outputs.insert( QStringLiteral( "OUTPUT" ), dest );
111 
112  long count = 0;
113  const long total = sourceA->featureCount();
114 
115  QgsOverlayUtils::intersection( *sourceA, *sourceB, *sink, context, feedback, count, total, fieldIndicesA, fieldIndicesB );
116 
117  return outputs;
118 }
119 
QgsProcessingFeedback
Base class for providing feedback from a processing algorithm.
Definition: qgsprocessingfeedback.h:37
QgsFields
Container of fields for a vector layer.
Definition: qgsfields.h:44
QgsProcessingUtils::indicesToFields
static QgsFields indicesToFields(const QList< int > &indices, const QgsFields &fields)
Returns a subset of fields based on the indices of desired fields.
Definition: qgsprocessingutils.cpp:1297
QgsProcessingParameterDefinition::FlagAdvanced
@ FlagAdvanced
Parameter is an advanced parameter which should be hidden from users by default.
Definition: qgsprocessingparameters.h:451
QgsProcessingParameterFeatureSource
An input feature source (such as vector layers) parameter for processing algorithms.
Definition: qgsprocessingparameters.h:3057
QgsWkbTypes::Type
Type
The WKB type describes the number of dimensions a geometry has.
Definition: qgswkbtypes.h:69
QgsWkbTypes::multiType
static Type multiType(Type type) SIP_HOLDGIL
Returns the multi type for a WKB type.
Definition: qgswkbtypes.h:304
QgsProcessingUtils::combineFields
static QgsFields combineFields(const QgsFields &fieldsA, const QgsFields &fieldsB, const QString &fieldsBPrefix=QString())
Combines two field lists, avoiding duplicate field names (in a case-insensitive manner).
Definition: qgsprocessingutils.cpp:1238
QgsProcessingParameterFeatureSink
A feature sink output for processing algorithms.
Definition: qgsprocessingparameters.h:3219
qgsgeometryengine.h
QgsProcessingContext
Contains information about the context in which a processing algorithm is executed.
Definition: qgsprocessingcontext.h:46
QgsProcessingUtils::fieldNamesToIndices
static QList< int > fieldNamesToIndices(const QStringList &fieldNames, const QgsFields &fields)
Returns a list of field indices parsed from the given list of field names.
Definition: qgsprocessingutils.cpp:1274
QgsFeatureSink::RegeneratePrimaryKey
@ RegeneratePrimaryKey
This flag indicates, that a primary key field cannot be guaranteed to be unique and the sink should i...
Definition: qgsfeaturesink.h:55
QgsProcessingAlgorithm
Abstract base class for processing algorithms.
Definition: qgsprocessingalgorithm.h:52
qgsalgorithmintersection.h
qgsgeometrycollection.h
qgsoverlayutils.h
QgsProcessingParameterField::Any
@ Any
Accepts any field.
Definition: qgsprocessingparameters.h:2947
QgsProcessingException
Custom exception class for processing related exceptions.
Definition: qgsexception.h:82
QgsProcessingParameterField
A vector layer or feature source field parameter for processing algorithms.
Definition: qgsprocessingparameters.h:2940