24 QString QgsBufferAlgorithm::name()
const
26 return QStringLiteral(
"buffer" );
29 QString QgsBufferAlgorithm::displayName()
const
31 return QObject::tr(
"Buffer" );
34 QStringList QgsBufferAlgorithm::tags()
const
36 return QObject::tr(
"buffer,grow,fixed,variable,distance" ).split(
',' );
39 QString QgsBufferAlgorithm::group()
const
41 return QObject::tr(
"Vector geometry" );
44 QString QgsBufferAlgorithm::groupId()
const
46 return QStringLiteral(
"vectorgeometry" );
49 void QgsBufferAlgorithm::initAlgorithm(
const QVariantMap & )
53 auto bufferParam = std::make_unique < QgsProcessingParameterDistance >( QStringLiteral(
"DISTANCE" ), QObject::tr(
"Distance" ), 10, QStringLiteral(
"INPUT" ) );
54 bufferParam->setIsDynamic(
true );
56 bufferParam->setDynamicLayerParameterName( QStringLiteral(
"INPUT" ) );
57 addParameter( bufferParam.release() );
59 segmentParam->setHelp( QObject::tr(
"The segments parameter controls the number of line segments to use to approximate a quarter circle when creating rounded offsets." ) );
60 addParameter( segmentParam.release() );
61 addParameter(
new QgsProcessingParameterEnum( QStringLiteral(
"END_CAP_STYLE" ), QObject::tr(
"End cap style" ), QStringList() << QObject::tr(
"Round" ) << QObject::tr(
"Flat" ) << QObject::tr(
"Square" ),
false, 0 ) );
62 addParameter(
new QgsProcessingParameterEnum( QStringLiteral(
"JOIN_STYLE" ), QObject::tr(
"Join style" ), QStringList() << QObject::tr(
"Round" ) << QObject::tr(
"Miter" ) << QObject::tr(
"Bevel" ),
false, 0 ) );
69 QString QgsBufferAlgorithm::shortHelpString()
const
71 return QObject::tr(
"This algorithm computes a buffer area for all the features in an input layer, using a fixed or dynamic distance.\n\n"
72 "The segments parameter controls the number of line segments to use to approximate a quarter circle when creating rounded offsets.\n\n"
73 "The end cap style parameter controls how line endings are handled in the buffer.\n\n"
74 "The join style parameter specifies whether round, miter or beveled joins should be used when offsetting corners in a line.\n\n"
75 "The miter limit parameter is only applicable for miter join styles, and controls the maximum distance from the offset curve to use when creating a mitered join." );
78 QgsBufferAlgorithm *QgsBufferAlgorithm::createInstance()
const
80 return new QgsBufferAlgorithm();
85 std::unique_ptr< QgsProcessingFeatureSource > source( parameterAsSource( parameters, QStringLiteral(
"INPUT" ), context ) );
90 std::unique_ptr< QgsFeatureSink > sink( parameterAsSink( parameters, QStringLiteral(
"OUTPUT" ), context, dest, source->fields(),
QgsWkbTypes::MultiPolygon, source->sourceCrs() ) );
95 const bool dissolve = parameterAsBoolean( parameters, QStringLiteral(
"DISSOLVE" ), context );
96 const int segments = parameterAsInt( parameters, QStringLiteral(
"SEGMENTS" ), context );
99 const double miterLimit = parameterAsDouble( parameters, QStringLiteral(
"MITER_LIMIT" ), context );
100 const double bufferDistance = parameterAsDouble( parameters, QStringLiteral(
"DISTANCE" ), context );
102 QgsExpressionContext expressionContext = createExpressionContext( parameters, context, source.get() );
106 bufferProperty = parameters.
value( QStringLiteral(
"DISTANCE" ) ).value<
QgsProperty >();
109 const long count = source->featureCount();
115 const double step = count > 0 ? 100.0 / count : 1;
118 QVector< QgsGeometry > bufferedGeometriesForDissolve;
127 if ( dissolveAttrs.isEmpty() )
133 double distance = bufferDistance;
137 distance = bufferProperty.
valueAsDouble( expressionContext, bufferDistance );
141 if ( outputGeometry.
isNull() )
143 QgsMessageLog::logMessage( QObject::tr(
"Error calculating buffer for feature %1" ).arg( f.
id() ), QObject::tr(
"Processing" ), Qgis::MessageLevel::Warning );
146 bufferedGeometriesForDissolve << outputGeometry;
176 outputs.insert( QStringLiteral(
"OUTPUT" ), dest );
180 QgsProcessingAlgorithm::Flags QgsBufferAlgorithm::flags()
const
190 if ( sink == QLatin1String(
"OUTPUT" ) )
194 const VectorProperties inputProps = sourceProperties.value( QStringLiteral(
"INPUT" ) );
195 result.
fields = inputProps.fields;
196 result.
crs = inputProps.crs;
203 std::unique_ptr< QgsProcessingFeatureSource > source( parameterAsSource( parameters, QStringLiteral(
"INPUT" ), context ) );
206 result.
fields = source->fields();
207 result.
crs = source->sourceCrs();
217 bool QgsBufferAlgorithm::supportInPlaceEdit(
const QgsMapLayer *layer )
const
219 const QgsVectorLayer *vlayer = qobject_cast< const QgsVectorLayer * >( layer );
223 return vlayer->
wkbType() == QgsWkbTypes::Type::Polygon || vlayer->
wkbType() == QgsWkbTypes::Type::MultiPolygon;
JoinStyle
Join styles for buffers.
EndCapStyle
End cap styles for buffers.
Expression contexts are used to encapsulate the parameters around which a QgsExpression should be eva...
void setFeature(const QgsFeature &feature)
Convenience function for setting a feature for the context.
Wrapper for iterator of features from vector data provider or vector layer.
bool nextFeature(QgsFeature &f)
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...
void setAttributes(const QgsAttributes &attrs)
Sets the feature's attributes.
bool hasGeometry() const
Returns true if the feature has an associated geometry.
void setGeometry(const QgsGeometry &geometry)
Set the feature's geometry.
bool isCanceled() const SIP_HOLDGIL
Tells whether the operation has been canceled already.
void setProgress(double progress)
Sets the current progress for the feedback object.
A geometry is the spatial representation of a feature.
static QgsGeometry unaryUnion(const QVector< QgsGeometry > &geometries)
Compute the unary union on a list of geometries.
QgsGeometry buffer(double distance, int segments) const
Returns a buffer region around this geometry having the given width and with a specified number of se...
bool convertToMultiType()
Converts single type geometry into multitype geometry e.g.
Base class for all map layer types.
static void logMessage(const QString &message, const QString &tag=QString(), Qgis::MessageLevel level=Qgis::MessageLevel::Warning, bool notifyUser=true)
Adds a message to the log instance (and creates it if necessary).
@ Available
Properties are available.
virtual Flags flags() const
Returns the flags indicating how and when the algorithm operates and should be exposed to users.
@ FlagSupportsInPlaceEdits
Algorithm supports in-place editing.
Contains information about the context in which a processing algorithm is executed.
Custom exception class for processing related exceptions.
@ FlagSkipGeometryValidityChecks
Invalid geometry checks should always be skipped. This flag can be useful for algorithms which always...
Base class for providing feedback from a processing algorithm.
A boolean parameter for processing algorithms.
An enum based parameter for processing algorithms, allowing for selection from predefined values.
A feature sink output for processing algorithms.
An input feature source (such as vector layers) parameter for processing algorithms.
A numeric parameter for processing algorithms.
@ Double
Double/float values.
static bool isDynamic(const QVariantMap ¶meters, const QString &name)
Returns true if the parameter with matching name is a dynamic parameter, and must be evaluated once f...
@ TypeVectorPolygon
Vector polygon layers.
Definition for a property.
@ Double
Double value (including negative values)
A store for object properties.
QVariant value(const QgsExpressionContext &context, const QVariant &defaultValue=QVariant(), bool *ok=nullptr) const
Calculates the current value of the property, including any transforms which are set for the property...
double valueAsDouble(const QgsExpressionContext &context, double defaultValue=0.0, bool *ok=nullptr) const
Calculates the current value of the property and interprets it as a double.
Represents a vector layer which manages a vector based data sets.
Q_INVOKABLE QgsWkbTypes::Type wkbType() const FINAL
Returns the WKBType or WKBUnknown in case of error.
Properties of a vector source or sink used in an algorithm.
QgsCoordinateReferenceSystem crs
Coordinate Reference System.
QgsWkbTypes::Type wkbType
Geometry (WKB) type.
QgsProcessingAlgorithm::PropertyAvailability availability
Availability of the properties. By default properties are not available.