QGIS API Documentation  3.9.0-Master (04f0879ed5)
Public Types | Static Public Member Functions | Friends | List of all members
QgsProcessingUtils Class Reference

Utility functions for use with processing classes. More...

#include <qgsprocessingutils.h>

Public Types

enum  LayerHint : int { LayerHint::UnknownType, LayerHint::Vector, LayerHint::Raster, LayerHint::Mesh }
 Layer type hints. More...
 

Static Public Member Functions

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). More...
 
static QgsRectangle combineLayerExtents (const QList< QgsMapLayer *> &layers, const QgsCoordinateReferenceSystem &crs, QgsProcessingContext &context)
 Combines the extent of several map layers. More...
 
static Q_DECL_DEPRECATED QgsRectangle combineLayerExtents (const QList< QgsMapLayer *> &layers, const QgsCoordinateReferenceSystem &crs=QgsCoordinateReferenceSystem())
 Combines the extent of several map layers. More...
 
static QList< QgsMapLayer *> compatibleLayers (QgsProject *project, bool sort=true)
 Returns a list of map layers from a project which are compatible with the processing framework. More...
 
static QList< QgsMeshLayer * > compatibleMeshLayers (QgsProject *project, bool sort=true)
 Returns a list of mesh layers from a project which are compatible with the processing framework. More...
 
static QList< QgsRasterLayer *> compatibleRasterLayers (QgsProject *project, bool sort=true)
 Returns a list of raster layers from a project which are compatible with the processing framework. More...
 
static QList< QgsVectorLayer *> compatibleVectorLayers (QgsProject *project, const QList< int > &sourceTypes=QList< int >(), bool sort=true)
 Returns a list of vector layers from a project which are compatible with the processing framework. More...
 
static QString convertToCompatibleFormat (const QgsVectorLayer *layer, bool selectedFeaturesOnly, const QString &baseName, const QStringList &compatibleFormats, const QString &preferredFormat, QgsProcessingContext &context, QgsProcessingFeedback *feedback)
 Converts a source vector layer to a file path to a vector layer of compatible format. More...
 
static QgsFeatureSinkcreateFeatureSink (QString &destination, QgsProcessingContext &context, const QgsFields &fields, QgsWkbTypes::Type geometryType, const QgsCoordinateReferenceSystem &crs, const QVariantMap &createOptions=QVariantMap(), QgsFeatureSink::SinkFlags sinkFlags=nullptr)
 Creates a feature sink ready for adding features. More...
 
static void createFeatureSinkPython (QgsFeatureSink **sink, QString &destination, QgsProcessingContext &context, const QgsFields &fields, QgsWkbTypes::Type geometryType, const QgsCoordinateReferenceSystem &crs, const QVariantMap &createOptions=QVariantMap()) SIP_THROW(QgsProcessingException)
 Creates a feature sink ready for adding features. More...
 
static QList< int > fieldNamesToIndices (const QStringList &fieldNames, const QgsFields &fields)
 Returns a list of field indices parsed from the given list of field names. More...
 
static QString formatHelpMapAsHtml (const QVariantMap &map, const QgsProcessingAlgorithm *algorithm)
 Returns a HTML formatted version of the help text encoded in a variant map for a specified algorithm. More...
 
static QVariant generateIteratingDestination (const QVariant &input, const QVariant &id, QgsProcessingContext &context)
 Converts an input parameter value for use in source iterating mode, where one individual sink is created per input feature. More...
 
static QString generateTempFilename (const QString &basename)
 Returns a temporary filename for a given file, putting it into a temporary folder (creating that folder in the process), but not changing the basename. More...
 
static QgsFields indicesToFields (const QList< int > &indices, const QgsFields &fields)
 Returns a subset of fields based on the indices of desired fields. More...
 
static QgsMapLayermapLayerFromString (const QString &string, QgsProcessingContext &context, bool allowLoadingNewLayers=true, QgsProcessingUtils::LayerHint typeHint=QgsProcessingUtils::LayerHint::UnknownType)
 Interprets a string as a map layer within the supplied context. More...
 
static QString normalizeLayerSource (const QString &source)
 Normalizes a layer source string for safe comparison across different operating system environments. More...
 
static QString stringToPythonLiteral (const QString &string)
 Converts a string to a Python string literal. More...
 
static QString tempFolder ()
 Returns a session specific processing temporary folder for use in processing algorithms. More...
 
static QString variantToPythonLiteral (const QVariant &value)
 Converts a variant to a Python literal. More...
 
static QgsProcessingFeatureSourcevariantToSource (const QVariant &value, QgsProcessingContext &context, const QVariant &fallbackValue=QVariant())
 Converts a variant value to a new feature source. More...
 

Friends

class QgsProcessingProvider
 
class TestQgsProcessing
 

Detailed Description

Utility functions for use with processing classes.

Since
QGIS 3.0

Definition at line 47 of file qgsprocessingutils.h.

Member Enumeration Documentation

◆ LayerHint

enum QgsProcessingUtils::LayerHint : int
strong

Layer type hints.

Since
QGIS 3.4
Enumerator
UnknownType 

Unknown layer type.

Vector 

Vector layer type.

Raster 

Raster layer type.

Mesh 

Mesh layer type.

Since
QGIS 3.6

Definition at line 112 of file qgsprocessingutils.h.

Member Function Documentation

◆ combineFields()

QgsFields QgsProcessingUtils::combineFields ( const QgsFields fieldsA,
const QgsFields fieldsB,
const QString &  fieldsBPrefix = QString() 
)
static

Combines two field lists, avoiding duplicate field names (in a case-insensitive manner).

Duplicate field names will be altered to "name_2", "name_3", etc, finding the first non-duplicate name.

Note
Some output file formats (e.g. shapefiles) have restrictions on the maximum length of field names, so be aware that the results of calling this method may be truncated when saving to these formats.

Definition at line 847 of file qgsprocessingutils.cpp.

◆ combineLayerExtents() [1/2]

QgsRectangle QgsProcessingUtils::combineLayerExtents ( const QList< QgsMapLayer *> &  layers,
const QgsCoordinateReferenceSystem crs,
QgsProcessingContext context 
)
static

Combines the extent of several map layers.

If specified, the target crs will be used to transform the layer's extent to the desired output reference system using the specified context.

Since
QGIS 3.8

Definition at line 630 of file qgsprocessingutils.cpp.

◆ combineLayerExtents() [2/2]

QgsRectangle QgsProcessingUtils::combineLayerExtents ( const QList< QgsMapLayer *> &  layers,
const QgsCoordinateReferenceSystem crs = QgsCoordinateReferenceSystem() 
)
static

Combines the extent of several map layers.

If specified, the target crs will be used to transform the layer's extent to the desired output reference system.

Deprecated:
Use version with QgsProcessingContext argument instead

Definition at line 663 of file qgsprocessingutils.cpp.

◆ compatibleLayers()

QList< QgsMapLayer * > QgsProcessingUtils::compatibleLayers ( QgsProject project,
bool  sort = true 
)
static

Returns a list of map layers from a project which are compatible with the processing framework.

If the sort argument is true then the layers will be sorted by their QgsMapLayer::name() value.

See also
compatibleRasterLayers()
compatibleVectorLayers()

Definition at line 106 of file qgsprocessingutils.cpp.

◆ compatibleMeshLayers()

QList< QgsMeshLayer * > QgsProcessingUtils::compatibleMeshLayers ( QgsProject project,
bool  sort = true 
)
static

Returns a list of mesh layers from a project which are compatible with the processing framework.

If the sort argument is true then the layers will be sorted by their QgsMapLayer::name() value.

See also
compatibleRasterLayers()
compatibleVectorLayers()
compatibleLayers()
Since
QGIS 3.6

Definition at line 83 of file qgsprocessingutils.cpp.

◆ compatibleRasterLayers()

QList< QgsRasterLayer * > QgsProcessingUtils::compatibleRasterLayers ( QgsProject project,
bool  sort = true 
)
static

Returns a list of raster layers from a project which are compatible with the processing framework.

If the sort argument is true then the layers will be sorted by their QgsMapLayer::name() value.

See also
compatibleVectorLayers()
compatibleMeshLayers()
compatibleLayers()

Definition at line 36 of file qgsprocessingutils.cpp.

◆ compatibleVectorLayers()

QList< QgsVectorLayer * > QgsProcessingUtils::compatibleVectorLayers ( QgsProject project,
const QList< int > &  sourceTypes = QList< int >(),
bool  sort = true 
)
static

Returns a list of vector layers from a project which are compatible with the processing framework.

The sourceTypes list should be filled with a list of QgsProcessing::SourceType values. If the sourceTypes list is non-empty then the layers will be sorted so that only layers with the specified source type included in the list will be returned. Leaving the sourceTypes list empty will cause all vector layers, regardless of their geometry type, to be returned.

If the sort argument is true then the layers will be sorted by their QgsMapLayer::name() value.

See also
compatibleRasterLayers()
compatibleMeshLayers()
compatibleLayers()

Definition at line 60 of file qgsprocessingutils.cpp.

◆ convertToCompatibleFormat()

QString QgsProcessingUtils::convertToCompatibleFormat ( const QgsVectorLayer layer,
bool  selectedFeaturesOnly,
const QString &  baseName,
const QStringList &  compatibleFormats,
const QString &  preferredFormat,
QgsProcessingContext context,
QgsProcessingFeedback feedback 
)
static

Converts a source vector layer to a file path to a vector layer of compatible format.

If the specified layer is not of the format listed in the compatibleFormats argument, then the layer will first be exported to a compatible format in a temporary location using baseName. The function will then return the path to that temporary file.

compatibleFormats should consist entirely of lowercase file extensions, e.g. 'shp'.

The preferredFormat argument is used to specify to desired file extension to use when a temporary layer export is required. This defaults to shapefiles.

Definition at line 781 of file qgsprocessingutils.cpp.

◆ createFeatureSink()

QgsFeatureSink * QgsProcessingUtils::createFeatureSink ( QString &  destination,
QgsProcessingContext context,
const QgsFields fields,
QgsWkbTypes::Type  geometryType,
const QgsCoordinateReferenceSystem crs,
const QVariantMap &  createOptions = QVariantMap(),
QgsFeatureSink::SinkFlags  sinkFlags = nullptr 
)
static

Creates a feature sink ready for adding features.

The destination specifies a destination URI for the resultant layer. It may be updated in place to reflect the actual destination for the layer.

Sink parameters such as desired encoding, fields, geometryType and crs must be specified.

The createOptions map can be used to specify additional sink creation options, which are passed to the underlying provider when creating new layers. Known options also include 'fileEncoding', which is used to specify a file encoding to use for created files. If 'fileEncoding' is not specified, the default encoding from the context will be used.

If a layer is created for the feature sink, the layer will automatically be added to the context's temporary layer store.

The caller takes responsibility for deleting the returned sink.

Definition at line 541 of file qgsprocessingutils.cpp.

◆ createFeatureSinkPython()

void QgsProcessingUtils::createFeatureSinkPython ( QgsFeatureSink **  sink,
QString &  destination,
QgsProcessingContext context,
const QgsFields fields,
QgsWkbTypes::Type  geometryType,
const QgsCoordinateReferenceSystem crs,
const QVariantMap &  createOptions = QVariantMap() 
)
static

Creates a feature sink ready for adding features.

The destination specifies a destination URI for the resultant layer. It may be updated in place to reflect the actual destination for the layer.

Sink parameters such as desired fields, geometryType and crs must be specified.

The createOptions map can be used to specify additional sink creation options, which are passed to the underlying provider when creating new layers. Known options also include 'fileEncoding', which is used to specify a file encoding to use for created files. If 'fileEncoding' is not specified, the default encoding from the context will be used.

If a layer is created for the feature sink, the layer will automatically be added to the context's temporary layer store.

Note
this version of the createFeatureSink() function has an API designed around use from the SIP bindings. c++ code should call the other createFeatureSink() version.
available in Python bindings as createFeatureSink()

Definition at line 624 of file qgsprocessingutils.cpp.

◆ fieldNamesToIndices()

QList< int > QgsProcessingUtils::fieldNamesToIndices ( const QStringList &  fieldNames,
const QgsFields fields 
)
static

Returns a list of field indices parsed from the given list of field names.

Unknown field names are ignored. If the list of field names is empty, it is assumed that all fields are required.

Since
QGIS 3.2

Definition at line 883 of file qgsprocessingutils.cpp.

◆ formatHelpMapAsHtml()

QString QgsProcessingUtils::formatHelpMapAsHtml ( const QVariantMap &  map,
const QgsProcessingAlgorithm algorithm 
)
static

Returns a HTML formatted version of the help text encoded in a variant map for a specified algorithm.

Definition at line 736 of file qgsprocessingutils.cpp.

◆ generateIteratingDestination()

QVariant QgsProcessingUtils::generateIteratingDestination ( const QVariant &  input,
const QVariant &  id,
QgsProcessingContext context 
)
static

Converts an input parameter value for use in source iterating mode, where one individual sink is created per input feature.

The id parameter represents the unique ID for this output, which is embedded into the resulting parameter value.

Definition at line 669 of file qgsprocessingutils.cpp.

◆ generateTempFilename()

QString QgsProcessingUtils::generateTempFilename ( const QString &  basename)
static

Returns a temporary filename for a given file, putting it into a temporary folder (creating that folder in the process), but not changing the basename.

See also
tempFolder()

Definition at line 724 of file qgsprocessingutils.cpp.

◆ indicesToFields()

QgsFields QgsProcessingUtils::indicesToFields ( const QList< int > &  indices,
const QgsFields fields 
)
static

Returns a subset of fields based on the indices of desired fields.

Since
QGIS 3.2

Definition at line 906 of file qgsprocessingutils.cpp.

◆ mapLayerFromString()

QgsMapLayer * QgsProcessingUtils::mapLayerFromString ( const QString &  string,
QgsProcessingContext context,
bool  allowLoadingNewLayers = true,
QgsProcessingUtils::LayerHint  typeHint = QgsProcessingUtils::LayerHint::UnknownType 
)
static

Interprets a string as a map layer within the supplied context.

The method will attempt to load a layer matching the passed string. E.g. if the string matches a layer ID or name within the context's project or temporary layer store then this layer will be returned. If the string is a file path and allowLoadingNewLayers is true, then the layer at this file path will be loaded and added to the context's temporary layer store. Ownership of the layer remains with the context or the context's current project.

The typeHint can be used to dictate the type of map layer expected.

Definition at line 270 of file qgsprocessingutils.cpp.

◆ normalizeLayerSource()

QString QgsProcessingUtils::normalizeLayerSource ( const QString &  source)
static

Normalizes a layer source string for safe comparison across different operating system environments.

Definition at line 385 of file qgsprocessingutils.cpp.

◆ stringToPythonLiteral()

QString QgsProcessingUtils::stringToPythonLiteral ( const QString &  string)
static

Converts a string to a Python string literal.

E.g. by replacing ' with \'.

See also
variantToPythonLiteral()

Definition at line 470 of file qgsprocessingutils.cpp.

◆ tempFolder()

QString QgsProcessingUtils::tempFolder ( )
static

Returns a session specific processing temporary folder for use in processing algorithms.

See also
generateTempFilename()

Definition at line 708 of file qgsprocessingutils.cpp.

◆ variantToPythonLiteral()

QString QgsProcessingUtils::variantToPythonLiteral ( const QVariant &  value)
static

Converts a variant to a Python literal.

See also
stringToPythonLiteral()
Since
QGSIS 3.6

Definition at line 392 of file qgsprocessingutils.cpp.

◆ variantToSource()

QgsProcessingFeatureSource * QgsProcessingUtils::variantToSource ( const QVariant &  value,
QgsProcessingContext context,
const QVariant &  fallbackValue = QVariant() 
)
static

Converts a variant value to a new feature source.

Sources will either be taken from context's active project, or loaded from external sources and stored temporarily in the context.

The optional fallbackValue can be used to specify a "default" value which is used if value cannot be successfully converted to a source.

This function creates a new object and the caller takes responsibility for deleting the returned object.

Definition at line 303 of file qgsprocessingutils.cpp.

Friends And Related Function Documentation

◆ QgsProcessingProvider

friend class QgsProcessingProvider
friend

Definition at line 348 of file qgsprocessingutils.h.

◆ TestQgsProcessing

friend class TestQgsProcessing
friend

Definition at line 347 of file qgsprocessingutils.h.


The documentation for this class was generated from the following files: