QGIS API Documentation 3.39.0-Master (67e056379ed)
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qgsalgorithmsaveselectedfeatures.cpp
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1/***************************************************************************
2 qgsalgorithmsaveselectedfeatures.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#include "qgsvectorlayer.h"
20
22
23void QgsSaveSelectedFeatures::initAlgorithm( const QVariantMap & )
24{
25 addParameter( new QgsProcessingParameterVectorLayer( QStringLiteral( "INPUT" ), QObject::tr( "Input layer" ),
26 QList< int >() << static_cast< int >( Qgis::ProcessingSourceType::Vector ) ) );
27 addParameter( new QgsProcessingParameterFeatureSink( QStringLiteral( "OUTPUT" ), QObject::tr( "Selected features" ) ) );
28}
29
30QString QgsSaveSelectedFeatures::name() const
31{
32 return QStringLiteral( "saveselectedfeatures" );
33}
34
35QString QgsSaveSelectedFeatures::displayName() const
36{
37 return QObject::tr( "Extract selected features" );
38}
39
40QStringList QgsSaveSelectedFeatures::tags() const
41{
42 return QObject::tr( "selection,save,by" ).split( ',' );
43}
44
45QString QgsSaveSelectedFeatures::group() const
46{
47 return QObject::tr( "Vector general" );
48}
49
50QString QgsSaveSelectedFeatures::groupId() const
51{
52 return QStringLiteral( "vectorgeneral" );
53}
54
55QString QgsSaveSelectedFeatures::shortHelpString() const
56{
57 return QObject::tr( "This algorithm creates a new layer with all the selected features in a given vector layer.\n\n"
58 "If the selected layer has no selected features, the newly created layer will be empty." );
59}
60
61QgsSaveSelectedFeatures *QgsSaveSelectedFeatures::createInstance() const
62{
63 return new QgsSaveSelectedFeatures();
64}
65
66bool QgsSaveSelectedFeatures::prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback * )
67{
68 QgsVectorLayer *selectLayer = parameterAsVectorLayer( parameters, QStringLiteral( "INPUT" ), context );
69 if ( !selectLayer )
70 throw QgsProcessingException( invalidSourceError( parameters, QStringLiteral( "INPUT" ) ) );
71
72 mSelection = selectLayer->selectedFeatureIds();
73 return true;
74}
75
76QVariantMap QgsSaveSelectedFeatures::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
77{
78 QgsVectorLayer *selectLayer = parameterAsVectorLayer( parameters, QStringLiteral( "INPUT" ), context );
79 if ( !selectLayer )
80 throw QgsProcessingException( invalidSourceError( parameters, QStringLiteral( "INPUT" ) ) );
81
82 QString dest;
83 std::unique_ptr< QgsFeatureSink > sink( parameterAsSink( parameters, QStringLiteral( "OUTPUT" ), context, dest, selectLayer->fields(), selectLayer->wkbType(), selectLayer->sourceCrs() ) );
84 if ( !sink )
85 throw QgsProcessingException( invalidSinkError( parameters, QStringLiteral( "OUTPUT" ) ) );
86
87
88 const int count = mSelection.count();
89 int current = 0;
90 const double step = count > 0 ? 100.0 / count : 1;
91
92 QgsFeatureIterator it = selectLayer->getFeatures( QgsFeatureRequest().setFilterFids( mSelection ) );
93 QgsFeature feat;
94 while ( it.nextFeature( feat ) )
95 {
96 if ( feedback->isCanceled() )
97 {
98 break;
99 }
100
101 if ( !sink->addFeature( feat, QgsFeatureSink::FastInsert ) )
102 throw QgsProcessingException( writeFeatureError( sink.get(), parameters, QStringLiteral( "OUTPUT" ) ) );
103
104 feedback->setProgress( current++ * step );
105 }
106
107 QVariantMap outputs;
108 outputs.insert( QStringLiteral( "OUTPUT" ), dest );
109 return outputs;
110}
111
113
114
115
@ Vector
Tables (i.e. vector layers with or without geometry). When used for a sink this indicates the sink ha...
Wrapper for iterator of features from vector data provider or vector layer.
bool nextFeature(QgsFeature &f)
Fetch next feature and stores in f, returns true on success.
This class wraps a request for features to a vector layer (or directly its vector data provider).
@ FastInsert
Use faster inserts, at the cost of updating the passed features to reflect changes made at the provid...
The feature class encapsulates a single feature including its unique ID, geometry and a list of field...
Definition qgsfeature.h:58
bool isCanceled() const
Tells whether the operation has been canceled already.
Definition qgsfeedback.h:53
void setProgress(double progress)
Sets the current progress for the feedback object.
Definition qgsfeedback.h:61
Contains information about the context in which a processing algorithm is executed.
Custom exception class for processing related exceptions.
Base class for providing feedback from a processing algorithm.
A feature sink output for processing algorithms.
A vector layer (with or without geometry) parameter for processing algorithms.
Represents a vector layer which manages a vector based data sets.
QgsFeatureIterator getFeatures(const QgsFeatureRequest &request=QgsFeatureRequest()) const FINAL
Queries the layer for features specified in request.
QgsCoordinateReferenceSystem sourceCrs() const FINAL
Returns the coordinate reference system for features in the source.
Q_INVOKABLE const QgsFeatureIds & selectedFeatureIds() const
Returns a list of the selected features IDs in this layer.
Q_INVOKABLE Qgis::WkbType wkbType() const FINAL
Returns the WKBType or WKBUnknown in case of error.