QGIS API Documentation
3.0.2-Girona (307d082)
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Abstract base class for processing algorithms. More...
#include <qgsprocessingalgorithm.h>
Public Types | |
enum | Flag { FlagHideFromToolbox = 1 << 1, FlagHideFromModeler = 1 << 2, FlagSupportsBatch = 1 << 3, FlagCanCancel = 1 << 4, FlagRequiresMatchingCrs = 1 << 5, FlagNoThreading = 1 << 6, FlagDeprecated = FlagHideFromToolbox | FlagHideFromModeler } |
Flags indicating how and when an algorithm operates and should be exposed to users. More... | |
Public Member Functions | |
QgsProcessingAlgorithm ()=default | |
Constructor for QgsProcessingAlgorithm. More... | |
QgsProcessingAlgorithm (const QgsProcessingAlgorithm &other)=delete | |
Algorithms cannot be copied - create() should be used instead. More... | |
virtual | ~QgsProcessingAlgorithm () |
virtual QString | asPythonCommand (const QVariantMap ¶meters, QgsProcessingContext &context) const |
Returns a Python command string which can be executed to run the algorithm using the specified parameters. More... | |
virtual bool | canExecute (QString *errorMessage=nullptr) const |
Returns true if the algorithm can execute. More... | |
virtual bool | checkParameterValues (const QVariantMap ¶meters, QgsProcessingContext &context, QString *message=nullptr) const |
Checks the supplied parameter values to verify that they satisfy the requirements of this algorithm in the supplied context. More... | |
int | countVisibleParameters () const |
Returns the number of visible (non-hidden) parameters defined by this algorithm. More... | |
QgsProcessingAlgorithm * | create (const QVariantMap &configuration=QVariantMap()) const |
Creates a copy of the algorithm, ready for execution. More... | |
virtual QWidget * | createCustomParametersWidget (QWidget *parent=nullptr) const |
If an algorithm subclass implements a custom parameters widget, a copy of this widget should be constructed and returned by this method. More... | |
QgsExpressionContext | createExpressionContext (const QVariantMap ¶meters, QgsProcessingContext &context, QgsProcessingFeatureSource *source=nullptr) const |
Creates an expression context relating to the algorithm. More... | |
QgsProcessingParameterDefinitions | destinationParameterDefinitions () const |
Returns a list of destination parameters definitions utilized by the algorithm. More... | |
virtual QString | displayName () const =0 |
Returns the translated algorithm name, which should be used for any user-visible display of the algorithm name. More... | |
virtual Flags | flags () const |
Returns the flags indicating how and when the algorithm operates and should be exposed to users. More... | |
virtual QString | group () const |
Returns the name of the group this algorithm belongs to. More... | |
virtual QString | groupId () const |
Returns the unique ID of the group this algorithm belongs to. More... | |
bool | hasHtmlOutputs () const |
Returns true if this algorithm generates HTML outputs. More... | |
virtual QString | helpString () const |
Returns a localised help string for the algorithm. More... | |
virtual QString | helpUrl () const |
Returns a url pointing to the algorithm's help page. More... | |
virtual QIcon | icon () const |
Returns an icon for the algorithm. More... | |
QString | id () const |
Returns the unique ID for the algorithm, which is a combination of the algorithm provider's ID and the algorithms unique name (e.g. More... | |
virtual QString | name () const =0 |
Returns the algorithm name, used for identifying the algorithm. More... | |
QgsProcessingAlgorithm & | operator= (const QgsProcessingAlgorithm &other)=delete |
Algorithms cannot be copied- create() should be used instead. More... | |
const QgsProcessingOutputDefinition * | outputDefinition (const QString &name) const |
Returns a matching output by name. More... | |
QgsProcessingOutputDefinitions | outputDefinitions () const |
Returns an ordered list of output definitions utilized by the algorithm. More... | |
const QgsProcessingParameterDefinition * | parameterDefinition (const QString &name) const |
Returns a matching parameter by name. More... | |
QgsProcessingParameterDefinitions | parameterDefinitions () const |
Returns an ordered list of parameter definitions utilized by the algorithm. More... | |
QVariantMap | postProcess (QgsProcessingContext &context, QgsProcessingFeedback *feedback) |
Should be called in the main thread following the completion of runPrepared(). More... | |
bool | prepare (const QVariantMap ¶meters, QgsProcessingContext &context, QgsProcessingFeedback *feedback) |
Prepares the algorithm for execution. More... | |
virtual QVariantMap | preprocessParameters (const QVariantMap ¶meters) |
Pre-processes a set of parameters, allowing the algorithm to clean their values. More... | |
QgsProcessingProvider * | provider () const |
Returns the provider to which this algorithm belongs. More... | |
QVariantMap | run (const QVariantMap ¶meters, QgsProcessingContext &context, QgsProcessingFeedback *feedback, bool *ok=nullptr) const |
Executes the algorithm using the specified parameters. More... | |
QVariantMap | runPrepared (const QVariantMap ¶meters, QgsProcessingContext &context, QgsProcessingFeedback *feedback) |
Runs the algorithm, which has been prepared by an earlier call to prepare(). More... | |
void | setProvider (QgsProcessingProvider *provider) |
Associates this algorithm with its provider. More... | |
virtual QString | shortHelpString () const |
Returns a localised short helper string for the algorithm. More... | |
virtual QString | svgIconPath () const |
Returns a path to an SVG version of the algorithm's icon. More... | |
virtual QStringList | tags () const |
Returns a list of tags which relate to the algorithm, and are used to assist users in searching for suitable algorithms. More... | |
virtual bool | validateInputCrs (const QVariantMap ¶meters, QgsProcessingContext &context) const |
Checks whether the coordinate reference systems for the specified set of parameters are valid for the algorithm. More... | |
Protected Member Functions | |
bool | addOutput (QgsProcessingOutputDefinition *outputDefinition) |
Adds an output definition to the algorithm. More... | |
bool | addParameter (QgsProcessingParameterDefinition *parameterDefinition, bool createOutput=true) |
Adds a parameter definition to the algorithm. More... | |
virtual QgsProcessingAlgorithm * | createInstance () const =0 |
Creates a new instance of the algorithm class. More... | |
virtual void | initAlgorithm (const QVariantMap &configuration=QVariantMap())=0 |
Initializes the algorithm using the specified configuration. More... | |
bool | parameterAsBool (const QVariantMap ¶meters, const QString &name, const QgsProcessingContext &context) const |
Evaluates the parameter with matching name to a static boolean value. More... | |
QString | parameterAsCompatibleSourceLayerPath (const QVariantMap ¶meters, const QString &name, QgsProcessingContext &context, const QStringList &compatibleFormats, const QString &preferredFormat=QString("shp"), QgsProcessingFeedback *feedback=nullptr) |
Evaluates the parameter with matching name to a source vector layer file path of compatible format. More... | |
QgsCoordinateReferenceSystem | parameterAsCrs (const QVariantMap ¶meters, const QString &name, QgsProcessingContext &context) const |
Evaluates the parameter with matching name to a coordinate reference system. More... | |
double | parameterAsDouble (const QVariantMap ¶meters, const QString &name, const QgsProcessingContext &context) const |
Evaluates the parameter with matching name to a static double value. More... | |
int | parameterAsEnum (const QVariantMap ¶meters, const QString &name, const QgsProcessingContext &context) const |
Evaluates the parameter with matching name to a enum value. More... | |
QList< int > | parameterAsEnums (const QVariantMap ¶meters, const QString &name, const QgsProcessingContext &context) const |
Evaluates the parameter with matching name to list of enum values. More... | |
QString | parameterAsExpression (const QVariantMap ¶meters, const QString &name, const QgsProcessingContext &context) const |
Evaluates the parameter with matching name to an expression. More... | |
QgsRectangle | parameterAsExtent (const QVariantMap ¶meters, const QString &name, QgsProcessingContext &context, const QgsCoordinateReferenceSystem &crs=QgsCoordinateReferenceSystem()) const |
Evaluates the parameter with matching name to a rectangular extent. More... | |
QgsCoordinateReferenceSystem | parameterAsExtentCrs (const QVariantMap ¶meters, const QString &name, QgsProcessingContext &context) |
Returns the coordinate reference system associated with an extent parameter value. More... | |
QgsGeometry | parameterAsExtentGeometry (const QVariantMap ¶meters, const QString &name, QgsProcessingContext &context, const QgsCoordinateReferenceSystem &crs=QgsCoordinateReferenceSystem()) |
Evaluates the parameter with matching name to a rectangular extent, and returns a geometry covering this extent. More... | |
QStringList | parameterAsFields (const QVariantMap ¶meters, const QString &name, QgsProcessingContext &context) const |
Evaluates the parameter with matching name to a list of fields. More... | |
QString | parameterAsFile (const QVariantMap ¶meters, const QString &name, QgsProcessingContext &context) const |
Evaluates the parameter with matching name to a file/folder name. More... | |
QString | parameterAsFileOutput (const QVariantMap ¶meters, const QString &name, QgsProcessingContext &context) const |
Evaluates the parameter with matching name to a file based output destination. More... | |
int | parameterAsInt (const QVariantMap ¶meters, const QString &name, const QgsProcessingContext &context) const |
Evaluates the parameter with matching name to a static integer value. More... | |
QgsMapLayer * | parameterAsLayer (const QVariantMap ¶meters, const QString &name, QgsProcessingContext &context) const |
Evaluates the parameter with matching name to a map layer. More... | |
QList< QgsMapLayer * > | parameterAsLayerList (const QVariantMap ¶meters, const QString &name, QgsProcessingContext &context) const |
Evaluates the parameter with matching name to a list of map layers. More... | |
QVariantList | parameterAsMatrix (const QVariantMap ¶meters, const QString &name, QgsProcessingContext &context) const |
Evaluates the parameter with matching name to a matrix/table of values. More... | |
QString | parameterAsOutputLayer (const QVariantMap ¶meters, const QString &name, QgsProcessingContext &context) const |
Evaluates the parameter with matching name to a output layer destination. More... | |
QgsPointXY | parameterAsPoint (const QVariantMap ¶meters, const QString &name, QgsProcessingContext &context, const QgsCoordinateReferenceSystem &crs=QgsCoordinateReferenceSystem()) const |
Evaluates the parameter with matching name to a point. More... | |
QgsCoordinateReferenceSystem | parameterAsPointCrs (const QVariantMap ¶meters, const QString &name, QgsProcessingContext &context) |
Returns the coordinate reference system associated with an point parameter value. More... | |
QList< double > | parameterAsRange (const QVariantMap ¶meters, const QString &name, QgsProcessingContext &context) const |
Evaluates the parameter with matching name to a range of values. More... | |
QgsRasterLayer * | parameterAsRasterLayer (const QVariantMap ¶meters, const QString &name, QgsProcessingContext &context) const |
Evaluates the parameter with matching name to a raster layer. More... | |
QgsFeatureSink * | parameterAsSink (const QVariantMap ¶meters, const QString &name, QgsProcessingContext &context, QString &destinationIdentifier, const QgsFields &fields, QgsWkbTypes::Type geometryType=QgsWkbTypes::NoGeometry, const QgsCoordinateReferenceSystem &crs=QgsCoordinateReferenceSystem()) const |
Evaluates the parameter with matching name to a feature sink. More... | |
QgsProcessingFeatureSource * | parameterAsSource (const QVariantMap ¶meters, const QString &name, QgsProcessingContext &context) const |
Evaluates the parameter with matching name to a feature source. More... | |
QString | parameterAsString (const QVariantMap ¶meters, const QString &name, const QgsProcessingContext &context) const |
Evaluates the parameter with matching name to a static string value. More... | |
QgsVectorLayer * | parameterAsVectorLayer (const QVariantMap ¶meters, const QString &name, QgsProcessingContext &context) const |
Evaluates the parameter with matching name to a vector layer. More... | |
virtual QVariantMap | postProcessAlgorithm (QgsProcessingContext &context, QgsProcessingFeedback *feedback) |
Allows the algorithm to perform any required cleanup tasks. More... | |
virtual bool | prepareAlgorithm (const QVariantMap ¶meters, QgsProcessingContext &context, QgsProcessingFeedback *feedback) |
Prepares the algorithm to run using the specified parameters. More... | |
virtual QVariantMap | processAlgorithm (const QVariantMap ¶meters, QgsProcessingContext &context, QgsProcessingFeedback *feedback)=0 |
Runs the algorithm using the specified parameters. More... | |
void | removeParameter (const QString &name) |
Removes the parameter with matching name from the algorithm, and deletes any existing definition. More... | |
Friends | |
class | QgsProcessingModelAlgorithm |
class | QgsProcessingProvider |
class | TestQgsProcessing |
Abstract base class for processing algorithms.
Definition at line 51 of file qgsprocessingalgorithm.h.
Flags indicating how and when an algorithm operates and should be exposed to users.
Definition at line 68 of file qgsprocessingalgorithm.h.
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default |
Constructor for QgsProcessingAlgorithm.
initAlgorithm() should be called after creating an algorithm to ensure it can correctly configure its parameterDefinitions() and outputDefinitions(). Alternatively, calling create() will return a pre-initialized copy of the algorithm.
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Definition at line 30 of file qgsprocessingalgorithm.cpp.
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Algorithms cannot be copied - create() should be used instead.
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Adds an output definition to the algorithm.
Ownership of the definition is transferred to the algorithm. Returns true if the output could be successfully added, or false if the output could not be added (e.g. as a result of a duplicate name).
This should usually be called from a subclass' initAlgorithm() implementation.
Note that in some cases output creation can be automatically performed when calling addParameter(). See the notes in addParameter() for a description of when this occurs.
Definition at line 285 of file qgsprocessingalgorithm.cpp.
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Adds a parameter definition to the algorithm.
Ownership of the definition is transferred to the algorithm. Returns true if parameter could be successfully added, or false if the parameter could not be added (e.g. as a result of a duplicate name).
This should usually be called from a subclass' initAlgorithm() implementation.
If the createOutput argument is true, then a corresponding output definition will also be created (and added to the algorithm) where appropriate. E.g. when adding a QgsProcessingParameterVectorDestination and createOutput is true, then a QgsProcessingOutputVectorLayer output will be created and added to the algorithm. There is no need to call addOutput() to manually add a corresponding output for this vector. If createOutput is false then this automatic output creation will not occur.
Definition at line 245 of file qgsprocessingalgorithm.cpp.
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Returns a Python command string which can be executed to run the algorithm using the specified parameters.
Algorithms which cannot be run from a Python command should return an empty string.
Definition at line 225 of file qgsprocessingalgorithm.cpp.
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Returns true if the algorithm can execute.
Algorithm subclasses can return false here to indicate that they are not able to execute, e.g. as a result of unmet external dependencies. If specified, the errorMessage argument will be filled with a localised error message describing why the algorithm cannot execute.
Definition at line 82 of file qgsprocessingalgorithm.cpp.
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virtual |
Checks the supplied parameter values to verify that they satisfy the requirements of this algorithm in the supplied context.
The message parameter will be filled with explanatory text if validation fails. Overridden implementations should also check this base class implementation.
Definition at line 87 of file qgsprocessingalgorithm.cpp.
int QgsProcessingAlgorithm::countVisibleParameters | ( | ) | const |
Returns the number of visible (non-hidden) parameters defined by this algorithm.
Definition at line 330 of file qgsprocessingalgorithm.cpp.
QgsProcessingAlgorithm * QgsProcessingAlgorithm::create | ( | const QVariantMap & | configuration = QVariantMap() | ) | const |
Creates a copy of the algorithm, ready for execution.
This method returns a new, preinitialized copy of the algorithm, ready for executing.
The configuration argument allows passing of a map of configuration settings to the algorithm, allowing it to dynamically adjust its initialized parameters and outputs according to this configuration. This is generally used only for algorithms in a model, allowing them to adjust their behavior at run time according to some user configuration.
Definition at line 36 of file qgsprocessingalgorithm.cpp.
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If an algorithm subclass implements a custom parameters widget, a copy of this widget should be constructed and returned by this method.
The base class implementation returns nullptr, which indicates that an autogenerated parameters widget should be used.
Definition at line 129 of file qgsprocessingalgorithm.cpp.
QgsExpressionContext QgsProcessingAlgorithm::createExpressionContext | ( | const QVariantMap & | parameters, |
QgsProcessingContext & | context, | ||
QgsProcessingFeatureSource * | source = nullptr |
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) | const |
Creates an expression context relating to the algorithm.
This can be called by algorithms to create a new expression context ready for evaluating expressions within the algorithm. Optionally, a source can be specified which will be used to populate the context if it implements the QgsExpressionContextGenerator interface.
Definition at line 134 of file qgsprocessingalgorithm.cpp.
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protectedpure virtual |
Creates a new instance of the algorithm class.
This method should return a 'pristine' instance of the algorithm class.
QgsProcessingParameterDefinitions QgsProcessingAlgorithm::destinationParameterDefinitions | ( | ) | const |
Returns a list of destination parameters definitions utilized by the algorithm.
Definition at line 341 of file qgsprocessingalgorithm.cpp.
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pure virtual |
Returns the translated algorithm name, which should be used for any user-visible display of the algorithm name.
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Returns the flags indicating how and when the algorithm operates and should be exposed to users.
Default flags are FlagSupportsBatch and FlagCanCancel.
Definition at line 77 of file qgsprocessingalgorithm.cpp.
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Returns the name of the group this algorithm belongs to.
This string should be localised.
Definition at line 200 of file qgsprocessingalgorithm.h.
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Returns the unique ID of the group this algorithm belongs to.
This string should be fixed for the algorithm, and must not be localised. The group id should be unique within each provider. Group id should contain lowercase alphanumeric characters only and no spaces or other formatting characters.
Definition at line 209 of file qgsprocessingalgorithm.h.
bool QgsProcessingAlgorithm::hasHtmlOutputs | ( | ) | const |
Returns true if this algorithm generates HTML outputs.
Definition at line 364 of file qgsprocessingalgorithm.cpp.
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Returns a localised help string for the algorithm.
Algorithm subclasses should implement either helpString() or helpUrl().
Definition at line 57 of file qgsprocessingalgorithm.cpp.
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Returns a url pointing to the algorithm's help page.
Definition at line 62 of file qgsprocessingalgorithm.cpp.
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Returns an icon for the algorithm.
Definition at line 67 of file qgsprocessingalgorithm.cpp.
QString QgsProcessingAlgorithm::id | ( | ) | const |
Returns the unique ID for the algorithm, which is a combination of the algorithm provider's ID and the algorithms unique name (e.g.
"qgis:mergelayers" ).
Definition at line 44 of file qgsprocessingalgorithm.cpp.
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protectedpure virtual |
Initializes the algorithm using the specified configuration.
This should be called directly after creating algorithms and before retrieving any parameterDefinitions() or outputDefinitions().
Subclasses should use their implementations to add all required input parameter and output definitions (which can be dynamically adjusted according to configuration).
Dynamic configuration can be used by algorithms which alter their behavior when used inside processing models. For instance, a "feature router" type algorithm which sends input features to one of any number of outputs sinks based on some preconfigured filter parameters can use the init method to create these outputs based on the specified configuration.
Implemented in QgsProcessingFeatureBasedAlgorithm.
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pure virtual |
Returns the algorithm name, used for identifying the algorithm.
This string should be fixed for the algorithm, and must not be localised. The name should be unique within each provider. Names should contain lowercase alphanumeric characters only and no spaces or other formatting characters.
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delete |
Algorithms cannot be copied- create() should be used instead.
const QgsProcessingOutputDefinition * QgsProcessingAlgorithm::outputDefinition | ( | const QString & | name | ) | const |
Returns a matching output by name.
Matching is done in a case-insensitive manner.
Definition at line 354 of file qgsprocessingalgorithm.cpp.
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Returns an ordered list of output definitions utilized by the algorithm.
Definition at line 282 of file qgsprocessingalgorithm.h.
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Evaluates the parameter with matching name to a static boolean value.
Definition at line 538 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a source vector layer file path of compatible format.
If the parameter is evaluated to an existing layer, and that 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. 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.
Definition at line 553 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a coordinate reference system.
Definition at line 583 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a static double value.
Definition at line 518 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a enum value.
Definition at line 528 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to list of enum values.
Definition at line 533 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to an expression.
Definition at line 513 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a rectangular extent.
If crs is set, and the original coordinate reference system of the parameter can be determined, then the extent will be automatically reprojected so that it is in the specified crs. In this case the extent of the reproject rectangle will be returned.
Definition at line 593 of file qgsprocessingalgorithm.cpp.
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Returns the coordinate reference system associated with an extent parameter value.
Definition at line 588 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a rectangular extent, and returns a geometry covering this extent.
If crs is set, and the original coordinate reference system of the parameter can be determined, then the extent will be automatically reprojected so that it is in the specified crs. Unlike parameterAsExtent(), the reprojected rectangle returned by this function will no longer be a rectangle itself (i.e. this method returns the geometry of the actual reprojected rectangle, while parameterAsExtent() returns just the extent of the reprojected rectangle).
Definition at line 598 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a list of fields.
Definition at line 633 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a file/folder name.
Definition at line 613 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a file based output destination.
Definition at line 573 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a static integer value.
Definition at line 523 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a map layer.
Layers will either be taken from context's active project, or loaded from external sources and stored temporarily in the context. In either case, callers do not need to handle deletion of the returned layer.
Definition at line 558 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a list of map layers.
Definition at line 623 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a matrix/table of values.
Tables are collapsed to a 1 dimensional list.
Definition at line 618 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a output layer destination.
Definition at line 568 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a point.
If crs is set then the point will be automatically reprojected so that it is in the specified crs.
Definition at line 603 of file qgsprocessingalgorithm.cpp.
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Returns the coordinate reference system associated with an point parameter value.
Definition at line 608 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a range of values.
Definition at line 628 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a raster layer.
Layers will either be taken from context's active project, or loaded from external sources and stored temporarily in the context. In either case, callers do not need to handle deletion of the returned layer.
Definition at line 563 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a feature sink.
Sinks will either be taken from context's active project, or created from external providers and stored temporarily in the context.
The fields, geometryType and crs parameters dictate the properties of the resulting feature sink.
The destinationIdentifier argument will be set to a string which can be used to retrieve the layer corresponding to the sink, e.g. via calling QgsProcessingUtils::mapLayerFromString().
This function creates a new object and the caller takes responsibility for deleting the returned object.
Definition at line 543 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a feature source.
Sources will either be taken from context's active project, or loaded from external sources and stored temporarily in the context.
This function creates a new object and the caller takes responsibility for deleting the returned object.
Definition at line 548 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a static string value.
Definition at line 508 of file qgsprocessingalgorithm.cpp.
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Evaluates the parameter with matching name to a vector layer.
Layers will either be taken from context's active project, or loaded from external sources and stored temporarily in the context. In either case, callers do not need to handle deletion of the returned layer.
Definition at line 578 of file qgsprocessingalgorithm.cpp.
const QgsProcessingParameterDefinition * QgsProcessingAlgorithm::parameterDefinition | ( | const QString & | name | ) | const |
Returns a matching parameter by name.
Matching is done in a case-insensitive manner, but exact case matches will be preferred.
Definition at line 312 of file qgsprocessingalgorithm.cpp.
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inline |
Returns an ordered list of parameter definitions utilized by the algorithm.
Definition at line 255 of file qgsprocessingalgorithm.h.
QVariantMap QgsProcessingAlgorithm::postProcess | ( | QgsProcessingContext & | context, |
QgsProcessingFeedback * | feedback | ||
) |
Should be called in the main thread following the completion of runPrepared().
This method allows the algorithm to perform any required cleanup tasks. The returned variant map includes the results evaluated by the algorithm.
Definition at line 479 of file qgsprocessingalgorithm.cpp.
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protectedvirtual |
Allows the algorithm to perform any required cleanup tasks.
The returned variant map includes the results evaluated by the algorithm. These may be output layer references, or calculated values such as statistical calculations.
The context argument specifies the context in which the algorithm was run.
Postprocess progress should be reported using the supplied feedback object. Additionally, well-behaved algorithms should periodically check feedback to determine whether the post processing should be canceled and exited early.
postProcessAlgorithm should be used to handle any thread-sensitive cleanup which is required by the algorithm. It will always be called from the same thread that context has thread affinity with. While this will generally be the main thread, it is not guaranteed. For instance, algorithms which are run as a step in a larger model or as a subcomponent of a script-based algorithm will call postProcessAlgorithm from the same thread as that model/script it being executed in.
postProcessAlgorithm will not be called if the prepareAlgorithm() step failed (returned false), or if an exception was raised by the processAlgorithm() step.
Definition at line 307 of file qgsprocessingalgorithm.cpp.
bool QgsProcessingAlgorithm::prepare | ( | const QVariantMap & | parameters, |
QgsProcessingContext & | context, | ||
QgsProcessingFeedback * | feedback | ||
) |
Prepares the algorithm for execution.
This must be run in the main thread, and allows the algorithm to pre-evaluate input parameters in a thread-safe manner. This must be called before calling runPrepared() (which is safe to do in any thread).
Definition at line 406 of file qgsprocessingalgorithm.cpp.
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protectedvirtual |
Prepares the algorithm to run using the specified parameters.
Algorithms should implement their logic for evaluating parameter values here. The evaluated parameter results should be stored in member variables ready for a call to processAlgorithm().
The context argument specifies the context in which the algorithm is being run.
prepareAlgorithm should be used to handle any thread-sensitive preparation which is required by the algorithm. It will always be called from the same thread that context has thread affinity with. While this will generally be the main thread, it is not guaranteed. For instance, algorithms which are run as a step in a larger model or as a subcomponent of a script-based algorithm will call prepareAlgorithm from the same thread as that model/script it being executed in.
Note that the processAlgorithm step uses a temporary context with affinity for the thread in which the algorithm is executed, making it safe for processAlgorithm implementations to load sources and sinks without issue. Implementing prepareAlgorithm is only required if special thread safe handling is required by the algorithm.
Algorithm preparation progress should be reported using the supplied feedback object. Additionally, well-behaved algorithms should periodically check feedback to determine whether the algorithm should be canceled and exited early.
If the preparation was successful algorithms must return true. If a false value is returned this indicates that the preparation could not be completed, and the algorithm execution will be canceled.
Definition at line 302 of file qgsprocessingalgorithm.cpp.
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virtual |
Pre-processes a set of parameters, allowing the algorithm to clean their values.
This method is automatically called after users enter parameters, e.g. via the algorithm dialog. This method should NOT be called manually by algorithms.
Definition at line 101 of file qgsprocessingalgorithm.cpp.
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protectedpure virtual |
Runs the algorithm using the specified parameters.
Algorithms should implement their custom processing logic here.
The context argument gives a temporary context with thread affinity matching the thread in which the algorithm is being run. This is a cut-back copy of the context passed to the prepareAlgorithm() and postProcessAlgorithm() steps, but it is generally safe for most algorithms to utilize this context for loading layers and creating sinks. Any loaded layers or sinks created within this temporary context will be transferred back to the main execution context upon successful completion of the processAlgorithm() step.
Algorithm progress should be reported using the supplied feedback object. Additionally, well-behaved algorithms should periodically check feedback to determine whether the algorithm should be canceled and exited early.
This method will not be called if the prepareAlgorithm() step failed (returned false).
c++ implementations of processAlgorithm can throw the QgsProcessingException exception to indicate that a fatal error occurred within the execution. Python based subclasses should raise GeoAlgorithmExecutionException for the same purpose.
Implemented in QgsProcessingFeatureBasedAlgorithm.
QgsProcessingProvider * QgsProcessingAlgorithm::provider | ( | ) | const |
Returns the provider to which this algorithm belongs.
Definition at line 106 of file qgsprocessingalgorithm.cpp.
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protected |
Removes the parameter with matching name from the algorithm, and deletes any existing definition.
Definition at line 275 of file qgsprocessingalgorithm.cpp.
QVariantMap QgsProcessingAlgorithm::run | ( | const QVariantMap & | parameters, |
QgsProcessingContext & | context, | ||
QgsProcessingFeedback * | feedback, | ||
bool * | ok = nullptr |
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) | const |
Executes the algorithm using the specified parameters.
This method internally creates a copy of the algorithm before running it, so it is safe to call on algorithms directly retrieved from QgsProcessingRegistry and QgsProcessingProvider.
The context argument specifies the context in which the algorithm is being run.
Algorithm progress should be reported using the supplied feedback object.
If specified, ok will be set to true if algorithm was successfully run.
Definition at line 374 of file qgsprocessingalgorithm.cpp.
QVariantMap QgsProcessingAlgorithm::runPrepared | ( | const QVariantMap & | parameters, |
QgsProcessingContext & | context, | ||
QgsProcessingFeedback * | feedback | ||
) |
Runs the algorithm, which has been prepared by an earlier call to prepare().
This method is safe to call from any thread. Returns true if the algorithm was successfully executed. After runPrepared() has finished, the postProcess() method should be called from the main thread to allow the algorithm to perform any required cleanup tasks and return its final result.
Definition at line 423 of file qgsprocessingalgorithm.cpp.
void QgsProcessingAlgorithm::setProvider | ( | QgsProcessingProvider * | provider | ) |
Associates this algorithm with its provider.
No transfer of ownership is involved.
Definition at line 111 of file qgsprocessingalgorithm.cpp.
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virtual |
Returns a localised short helper string for the algorithm.
This string should provide a basic description about what the algorithm does and the parameters and outputs associated with it.
Definition at line 52 of file qgsprocessingalgorithm.cpp.
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virtual |
Returns a path to an SVG version of the algorithm's icon.
Definition at line 72 of file qgsprocessingalgorithm.cpp.
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inlinevirtual |
Returns a list of tags which relate to the algorithm, and are used to assist users in searching for suitable algorithms.
These tags should be localised.
Definition at line 157 of file qgsprocessingalgorithm.h.
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virtual |
Checks whether the coordinate reference systems for the specified set of parameters are valid for the algorithm.
For instance, the base implementation performs checks to ensure that all input CRS are equal Returns true if parameters have passed the CRS check.
Definition at line 158 of file qgsprocessingalgorithm.cpp.
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friend |
Definition at line 761 of file qgsprocessingalgorithm.h.
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friend |
Definition at line 759 of file qgsprocessingalgorithm.h.
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friend |
Definition at line 760 of file qgsprocessingalgorithm.h.