QGIS API Documentation  3.2.0-Bonn (bc43194)
qgsalgorithmextractbyextent.cpp
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1 /***************************************************************************
2  qgsalgorithmextractbyextent.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 
19 
21 
22 QString QgsExtractByExtentAlgorithm::name() const
23 {
24  return QStringLiteral( "extractbyextent" );
25 }
26 
27 QString QgsExtractByExtentAlgorithm::displayName() const
28 {
29  return QObject::tr( "Extract/clip by extent" );
30 }
31 
32 QStringList QgsExtractByExtentAlgorithm::tags() const
33 {
34  return QObject::tr( "clip,extract,intersect,intersection,mask,extent" ).split( ',' );
35 }
36 
37 QString QgsExtractByExtentAlgorithm::group() const
38 {
39  return QObject::tr( "Vector overlay" );
40 }
41 
42 QString QgsExtractByExtentAlgorithm::groupId() const
43 {
44  return QStringLiteral( "vectoroverlay" );
45 }
46 void QgsExtractByExtentAlgorithm::initAlgorithm( const QVariantMap & )
47 {
48  addParameter( new QgsProcessingParameterFeatureSource( QStringLiteral( "INPUT" ), QObject::tr( "Input layer" ) ) );
49  addParameter( new QgsProcessingParameterExtent( QStringLiteral( "EXTENT" ), QObject::tr( "Extent" ) ) );
50  addParameter( new QgsProcessingParameterBoolean( QStringLiteral( "CLIP" ), QObject::tr( "Clip features to extent" ), false ) );
51  addParameter( new QgsProcessingParameterFeatureSink( QStringLiteral( "OUTPUT" ), QObject::tr( "Extracted" ) ) );
52 }
53 
54 QString QgsExtractByExtentAlgorithm::shortHelpString() const
55 {
56  return QObject::tr( "This algorithm creates a new vector layer that only contains features which fall within a specified extent. "
57  "Any features which intersect the extent will be included.\n\n"
58  "Optionally, feature geometries can also be clipped to the extent. If this option is selected, then the output "
59  "geometries will automatically be converted to multi geometries to ensure uniform output geometry types." );
60 }
61 
62 QgsExtractByExtentAlgorithm *QgsExtractByExtentAlgorithm::createInstance() const
63 {
64  return new QgsExtractByExtentAlgorithm();
65 }
66 
67 QVariantMap QgsExtractByExtentAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
68 {
69  std::unique_ptr< QgsFeatureSource > featureSource( parameterAsSource( parameters, QStringLiteral( "INPUT" ), context ) );
70  if ( !featureSource )
71  throw QgsProcessingException( invalidSourceError( parameters, QStringLiteral( "INPUT" ) ) );
72 
73  QgsRectangle extent = parameterAsExtent( parameters, QStringLiteral( "EXTENT" ), context, featureSource->sourceCrs() );
74  bool clip = parameterAsBool( parameters, QStringLiteral( "CLIP" ), context );
75 
76  // if clipping, we force multi output
77  QgsWkbTypes::Type outType = clip ? QgsWkbTypes::multiType( featureSource->wkbType() ) : featureSource->wkbType();
78 
79  QString dest;
80  std::unique_ptr< QgsFeatureSink > sink( parameterAsSink( parameters, QStringLiteral( "OUTPUT" ), context, dest, featureSource->fields(), outType, featureSource->sourceCrs() ) );
81 
82  if ( !sink )
83  throw QgsProcessingException( invalidSinkError( parameters, QStringLiteral( "OUTPUT" ) ) );
84 
85  QgsGeometry clipGeom = parameterAsExtentGeometry( parameters, QStringLiteral( "EXTENT" ), context, featureSource->sourceCrs() );
86 
87  double step = featureSource->featureCount() > 0 ? 100.0 / featureSource->featureCount() : 1;
88  QgsFeatureIterator inputIt = featureSource->getFeatures( QgsFeatureRequest().setFilterRect( extent ).setFlags( QgsFeatureRequest::ExactIntersect ) );
89  QgsFeature f;
90  int i = -1;
91  while ( inputIt.nextFeature( f ) )
92  {
93  i++;
94  if ( feedback->isCanceled() )
95  {
96  break;
97  }
98 
99  if ( clip )
100  {
101  QgsGeometry g = f.geometry().intersection( clipGeom );
102  g.convertToMultiType();
103  f.setGeometry( g );
104  }
105 
106  sink->addFeature( f, QgsFeatureSink::FastInsert );
107  feedback->setProgress( i * step );
108  }
109 
110  QVariantMap outputs;
111  outputs.insert( QStringLiteral( "OUTPUT" ), dest );
112  return outputs;
113 }
114 
116 
A boolean parameter for processing algorithms.
Wrapper for iterator of features from vector data provider or vector layer.
Use faster inserts, at the cost of updating the passed features to reflect changes made at the provid...
A rectangle specified with double values.
Definition: qgsrectangle.h:40
static Type multiType(Type type)
Returns the multi type for a WKB type.
Definition: qgswkbtypes.h:296
Base class for providing feedback from a processing algorithm.
Use exact geometry intersection (slower) instead of bounding boxes.
void setProgress(double progress)
Sets the current progress for the feedback object.
Definition: qgsfeedback.h:63
A geometry is the spatial representation of a feature.
Definition: qgsgeometry.h:104
QgsGeometry intersection(const QgsGeometry &geometry) const
Returns a geometry representing the points shared by this geometry and other.
The feature class encapsulates a single feature including its id, geometry and a list of field/values...
Definition: qgsfeature.h:62
A feature sink output for processing algorithms.
Type
The WKB type describes the number of dimensions a geometry has.
Definition: qgswkbtypes.h:67
This class wraps a request for features to a vector layer (or directly its vector data provider)...
Custom exception class for processing related exceptions.
Definition: qgsexception.h:82
QgsGeometry geometry() const
Returns the geometry associated with this feature.
Definition: qgsfeature.cpp:101
A rectangular map extent parameter for processing algorithms.
bool convertToMultiType()
Converts single type geometry into multitype geometry e.g.
bool isCanceled() const
Tells whether the operation has been canceled already.
Definition: qgsfeedback.h:54
An input feature source (such as vector layers) parameter for processing algorithms.
void setGeometry(const QgsGeometry &geometry)
Set the feature&#39;s geometry.
Definition: qgsfeature.cpp:137
bool nextFeature(QgsFeature &f)
Contains information about the context in which a processing algorithm is executed.