26QString QgsMultiDifferenceAlgorithm::name()
const
28 return QStringLiteral(
"multidifference" );
31QString QgsMultiDifferenceAlgorithm::displayName()
const
33 return QObject::tr(
"Difference (multiple)" );
36QStringList QgsMultiDifferenceAlgorithm::tags()
const
38 return QObject::tr(
"difference,erase,not overlap" ).split(
',' );
41QString QgsMultiDifferenceAlgorithm::group()
const
43 return QObject::tr(
"Vector overlay" );
46QString QgsMultiDifferenceAlgorithm::groupId()
const
48 return QStringLiteral(
"vectoroverlay" );
51QString QgsMultiDifferenceAlgorithm::shortHelpString()
const
53 return QObject::tr(
"This algorithm extracts features from the Input layer that fall completely outside or only partially overlap the features from any of the Overlay layer(s). "
54 "For each overlay layer the difference is calculated between the result of all previous difference operations and this overlay layer. "
55 "Input layer features that partially overlap feature(s) in the Overlay layers are split along those features' boundary "
56 "and only the portions outside the Overlay layer features are retained." )
57 + QStringLiteral(
"\n\n" )
58 + QObject::tr(
"Attributes are not modified, although properties such as area or length of the features will "
59 "be modified by the difference operation. If such properties are stored as attributes, those attributes will have to "
60 "be manually updated." );
65 return new QgsMultiDifferenceAlgorithm();
68void QgsMultiDifferenceAlgorithm::initAlgorithm(
const QVariantMap & )
78 std::unique_ptr< QgsFeatureSource > sourceA( parameterAsSource( parameters, QStringLiteral(
"INPUT" ), context ) );
82 const QList< QgsMapLayer * > layers = parameterAsLayerList( parameters, QStringLiteral(
"OVERLAYS" ), context );
85 long totalLayerCount = 0;
102 std::unique_ptr< QgsFeatureSink > sink;
106 if ( totalLayerCount == 1 )
109 sink.reset( parameterAsSink( parameters, QStringLiteral(
"OUTPUT" ), context, dest, sourceA->fields(), geometryType,
crs ) );
113 outputs.insert( QStringLiteral(
"OUTPUT" ), dest );
115 QgsVectorLayer *overlayLayer = qobject_cast< QgsVectorLayer * >( layers.at( 0 ) );
117 const long total = sourceA->featureCount();
118 QgsOverlayUtils::difference( *sourceA, *overlayLayer, *sink, context, feedback, count, total, QgsOverlayUtils::OutputA );
131 multiStepFeedback.setCurrentStep( i );
136 QgsVectorLayer *overlayLayer = qobject_cast< QgsVectorLayer * >( layer );
143 QString
id = QStringLiteral(
"memory:" );
145 QgsOverlayUtils::difference( *sourceA, *overlayLayer, *sink, context, &multiStepFeedback, count, sourceA->featureCount(), QgsOverlayUtils::OutputA );
149 else if ( i == totalLayerCount - 1 )
152 std::unique_ptr< QgsFeatureSink > sink( parameterAsSink( parameters, QStringLiteral(
"OUTPUT" ), context, dest, differenceLayer->
fields(), geometryType,
crs ) );
156 outputs.insert( QStringLiteral(
"OUTPUT" ), dest );
158 QgsOverlayUtils::difference( *differenceLayer, *overlayLayer, *sink, context, &multiStepFeedback, count, differenceLayer->
featureCount(), QgsOverlayUtils::OutputA );
162 QString
id = QStringLiteral(
"memory:" );
164 QgsOverlayUtils::difference( *differenceLayer, *overlayLayer, *sink, context, &multiStepFeedback, count, differenceLayer->
featureCount(), QgsOverlayUtils::OutputA );
@ VectorAnyGeometry
Any vector layer with geometry.
WkbType
The WKB type describes the number of dimensions a geometry has.
This class represents a coordinate reference system (CRS).
bool isCanceled() const
Tells whether the operation has been canceled already.
Base class for all map layer types.
Abstract base class for processing algorithms.
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.
Processing feedback object for multi-step operations.
A feature sink output for processing algorithms.
An input feature source (such as vector layers) parameter for processing algorithms.
A parameter for processing algorithms which accepts multiple map layers.
static QgsFeatureSink * createFeatureSink(QString &destination, QgsProcessingContext &context, const QgsFields &fields, Qgis::WkbType geometryType, const QgsCoordinateReferenceSystem &crs, const QVariantMap &createOptions=QVariantMap(), const QStringList &datasourceOptions=QStringList(), const QStringList &layerOptions=QStringList(), QgsFeatureSink::SinkFlags sinkFlags=QgsFeatureSink::SinkFlags(), QgsRemappingSinkDefinition *remappingDefinition=nullptr)
Creates a feature sink ready for adding features.
static QgsMapLayer * mapLayerFromString(const QString &string, QgsProcessingContext &context, bool allowLoadingNewLayers=true, QgsProcessingUtils::LayerHint typeHint=QgsProcessingUtils::LayerHint::UnknownType, QgsProcessing::LayerOptionsFlags flags=QgsProcessing::LayerOptionsFlags())
Interprets a string as a map layer within the supplied context.
Represents a vector layer which manages a vector based data sets.
long long featureCount(const QString &legendKey) const
Number of features rendered with specified legend key.
static Qgis::WkbType multiType(Qgis::WkbType type)
Returns the multi type for a WKB type.
const QgsCoordinateReferenceSystem & crs