QgsLayerDefinition Class Reference

The QgsLayerDefinition class holds generic methods for loading/exporting QLR files. More...

#include <qgslayerdefinition.h>

Classes
class	DependencySorter
	Class used to work with layer dependencies stored in a XML project or layer definition file. More...

Static Public Member Functions
static bool	exportLayerDefinition (const QString &path, const QList< QgsLayerTreeNode * > &selectedTreeNodes, Qgis::FilePathType pathType, QString &errorMessage)
	Exports the selected layer tree nodes to a QLR file.
static bool	exportLayerDefinition (const QString &path, const QList< QgsLayerTreeNode * > &selectedTreeNodes, QString &errorMessage)
	Exports the selected layer tree nodes to a QLR file.
static bool	exportLayerDefinition (QDomDocument doc, const QList< QgsLayerTreeNode * > &selectedTreeNodes, QString &errorMessage, const QgsReadWriteContext &context)
	Exports the selected layer tree nodes to a QLR XML document.
static QDomDocument	exportLayerDefinitionLayers (const QList< QgsMapLayer * > &layers, const QgsReadWriteContext &context)
	Returns the given layer as a layer definition document Layer definitions store the data source as well as styling and custom properties.
static bool	loadLayerDefinition (const QString &path, QgsProject *project, QgsLayerTreeGroup *rootGroup, QString &errorMessage, Qgis::LayerTreeInsertionMethod insertMethod=Qgis::LayerTreeInsertionMethod::OptimalInInsertionGroup, const QgsLayerTreeRegistryBridge::InsertionPoint *insertPoint=nullptr)
	Loads the QLR at path into QGIS.
static bool	loadLayerDefinition (QDomDocument doc, QgsProject *project, QgsLayerTreeGroup *rootGroup, QString &errorMessage, QgsReadWriteContext &context, Qgis::LayerTreeInsertionMethod insertMethod=Qgis::LayerTreeInsertionMethod::OptimalInInsertionGroup, const QgsLayerTreeRegistryBridge::InsertionPoint *insertPoint=nullptr)
	Loads the QLR from the XML document.
static QList< QgsMapLayer * >	loadLayerDefinitionLayers (const QString &qlrfile)
	Creates new layers from a layer definition file (.QLR) This is a low-level routine that does not resolve layer ID conflicts, dependencies and joins.
static QList< QgsMapLayer * >	loadLayerDefinitionLayers (QDomDocument &document, QgsReadWriteContext &context)
	Creates new layers from a layer definition document.

Detailed Description

The QgsLayerDefinition class holds generic methods for loading/exporting QLR files.

QLR files are an export of the layer xml including the style and datasource location. There is no link to the QLR file once loaded. Consider the QLR file a mini project file for layers and styles. QLR files also store the layer tree info for the exported layers, including group information.

Definition at line 45 of file qgslayerdefinition.h.

Member Function Documentation

exportLayerDefinition() [1/3]

bool QgsLayerDefinition::exportLayerDefinition ( const QString &  path, const QList< QgsLayerTreeNode * > &  selectedTreeNodes, Qgis::FilePathType  pathType, QString &  errorMessage  )

static

Exports the selected layer tree nodes to a QLR file.

Parameters

path	file path for exported QLR file
selectedTreeNodes	layer tree nodes to include in the QLR file
pathType	specifies whether absolute or relative file paths should be used.
errorMessage	will be set to any error messages generated during the export

Returns

true if the export was successful

Since

QGIS 3.22

Definition at line 225 of file qgslayerdefinition.cpp.

exportLayerDefinition() [2/3]

bool QgsLayerDefinition::exportLayerDefinition ( const QString &  path, const QList< QgsLayerTreeNode * > &  selectedTreeNodes, QString &  errorMessage  )

static

Exports the selected layer tree nodes to a QLR file.

This method uses the QgsProject.instance()'s file path setting to determine whether absolute or relative paths are written. Use the variant with an explicit argument for file path type for control over this setting.

Parameters

path	file path for exported QLR file
selectedTreeNodes	layer tree nodes to include in the QLR file
errorMessage	will be set to any error messages generated during the export

Returns

true if the export was successful

Definition at line 220 of file qgslayerdefinition.cpp.

exportLayerDefinition() [3/3]

bool QgsLayerDefinition::exportLayerDefinition ( QDomDocument  doc, const QList< QgsLayerTreeNode * > &  selectedTreeNodes, QString &  errorMessage, const QgsReadWriteContext &  context  )

static

Exports the selected layer tree nodes to a QLR XML document.

Definition at line 256 of file qgslayerdefinition.cpp.

exportLayerDefinitionLayers()

QDomDocument QgsLayerDefinition::exportLayerDefinitionLayers ( const QList< QgsMapLayer * > &  layers, const QgsReadWriteContext &  context  )

static

Returns the given layer as a layer definition document Layer definitions store the data source as well as styling and custom properties.

Layer definitions can be used to load a layer and styling all from a single file.

This is a low-level routine that does not write layer tree.

See also

exportLayerDefinition()

Definition at line 289 of file qgslayerdefinition.cpp.

loadLayerDefinition() [1/2]

bool QgsLayerDefinition::loadLayerDefinition ( const QString &  path, QgsProject *  project, QgsLayerTreeGroup *  rootGroup, QString &  errorMessage, Qgis::LayerTreeInsertionMethod  insertMethod = Qgis::LayerTreeInsertionMethod::OptimalInInsertionGroup, const QgsLayerTreeRegistryBridge::InsertionPoint *  insertPoint = nullptr  )

static

Loads the QLR at path into QGIS.

New layers are added to given project into layer tree specified by rootGroup

Parameters

path	file path to the qlr
project	the current project
rootGroup	the layer tree group to insert the qlr content
errorMessage	the returned error message
insertMethod	method for layer tree (since QGIS 3.38)
insertPoint	describes where in rootGroup the qlr layers/groups shall be inserted (since QGIS 3.38)

Returns

true in case of success

Definition at line 41 of file qgslayerdefinition.cpp.

loadLayerDefinition() [2/2]

bool QgsLayerDefinition::loadLayerDefinition ( QDomDocument  doc, QgsProject *  project, QgsLayerTreeGroup *  rootGroup, QString &  errorMessage, QgsReadWriteContext &  context, Qgis::LayerTreeInsertionMethod  insertMethod = Qgis::LayerTreeInsertionMethod::OptimalInInsertionGroup, const QgsLayerTreeRegistryBridge::InsertionPoint *  insertPoint = nullptr  )

static

Loads the QLR from the XML document.

New layers are added to given project into layer tree specified by rootGroup

Parameters

doc	the xml document
project	the current project
rootGroup	the layer tree group to insert the qlr content
errorMessage	the returned error message
context	the read write context
insertMethod	method for layer tree (since QGIS 3.38)
insertPoint	describes where in rootGroup the qlr layers/groups shall be inserted (since QGIS 3.38)

Returns

true in case of success

Definition at line 68 of file qgslayerdefinition.cpp.

loadLayerDefinitionLayers() [1/2]

QList< QgsMapLayer * > QgsLayerDefinition::loadLayerDefinitionLayers ( const QString &  qlrfile )

static

Creates new layers from a layer definition file (.QLR) This is a low-level routine that does not resolve layer ID conflicts, dependencies and joins.

See also

loadLayerDefinition()

Definition at line 389 of file qgslayerdefinition.cpp.

loadLayerDefinitionLayers() [2/2]

QList< QgsMapLayer * > QgsLayerDefinition::loadLayerDefinitionLayers ( QDomDocument &  document, QgsReadWriteContext &  context  )

static

Creates new layers from a layer definition document.

This is a low-level routine that does not resolve layer ID conflicts, dependencies and joins

See also

loadLayerDefinition()

Definition at line 306 of file qgslayerdefinition.cpp.

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

• /build/qgis-3.41.0+git20241122+3440c17df1d+99sid/src/core/qgslayerdefinition.h
• /build/qgis-3.41.0+git20241122+3440c17df1d+99sid/src/core/qgslayerdefinition.cpp