Internal structure to keep weak pointer to QgsMapLayer or layerId if the layer is not available yet. More...

#include <qgsmaplayerref.h>

Public Types
enum	MatchType { Name = 1 << 2 , Provider = 1 << 3 , Source = 1 << 4 , All = Provider \| Source }
	Flag for match type in weak resolution. More...

Public Member Functions
	_LayerRef (const QString &id, const QString &name=QString(), const QString &source=QString(), const QString &provider=QString())
	Constructor for a weak layer reference, using a combination of layer ID, name, public source and provider key.

	_LayerRef (TYPE *l=nullptr)
	Constructor for a layer reference from an existing map layer.

TYPE *	get () const
	Returns a pointer to the layer, or `nullptr` if the reference has not yet been matched to a layer.

bool	layerMatchesSource (QgsMapLayer *layer) const
	Returns `true` if a layer matches the weak references to layer public source, layer name and data provider contained in this layer reference.

bool	layerMatchesWeakly (QgsMapLayer *layer, MatchType matchType=MatchType::All) const

	operator bool () const
	Returns `true` if the layer reference is resolved and contains a reference to an existing map layer.

TYPE *	operator-> () const
	Forwards the to map layer.

bool	operator== (const _LayerRef &other)=delete
	Equality operator is deleted to avoid confusion as there are multiple ways two _LayerRef objects can be considered equal.

bool	readXml (const QDomElement &element, const QgsReadWriteContext &context)
	Reads the layer's properties from an XML element.

TYPE *	resolve (const QgsProject *project)
	Resolves the map layer by attempting to find a layer with matching ID within a project.

TYPE *	resolveByIdOrNameOnly (const QgsProject *project)
	Resolves the map layer by attempting to find a matching layer in a project using a weak match.

TYPE *	resolveWeakly (const QgsProject *project, MatchType matchType=MatchType::All)
	Resolves the map layer by attempting to find a matching layer in a project using a weak match.

void	setLayer (TYPE *l)
	Sets the reference to point to a specified layer.

void	writeXml (QDomElement &element, const QgsReadWriteContext &context) const
	Writes the layer's properties to a XML element.

Public Attributes
QPointer< TYPE >	layer
	Weak pointer to map layer.

QString	layerId
	Original layer ID.

QString	name
	Weak reference to layer name.

QString	provider
	Weak reference to layer provider.

QString	source
	Weak reference to layer public source.

Detailed Description

template<typename TYPE>
struct _LayerRef< TYPE >

Internal structure to keep weak pointer to QgsMapLayer or layerId if the layer is not available yet.

Note: not available in Python bindings

Definition at line 35 of file qgsmaplayerref.h.

Member Enumeration Documentation

◆ MatchType

template<typename TYPE >

enum _LayerRef::MatchType

Flag for match type in weak resolution.

Since: QGIS 3.12

Enumerator
Name	Match layer name.
Provider	Match layer provider name.
Source	Match layer source.
All	Match all.

Definition at line 42 of file qgsmaplayerref.h.

Constructor & Destructor Documentation

◆ _LayerRef() [1/2]

template<typename TYPE >

_LayerRef< TYPE >::_LayerRef ( TYPE * l = nullptr )

inline

Constructor for a layer reference from an existing map layer.

The layerId, source, name and provider members will automatically be populated from this layer.

Definition at line 56 of file qgsmaplayerref.h.

◆ _LayerRef() [2/2]

template<typename TYPE >

_LayerRef< TYPE >::_LayerRef	(	const QString &	id,
		const QString &	name = `QString()`,
		const QString &	source = `QString()`,
		const QString &	provider = `QString()`
	)

inline

Constructor for a weak layer reference, using a combination of layer ID, name, public source and provider key.

Definition at line 68 of file qgsmaplayerref.h.

Member Function Documentation

◆ get()

template<typename TYPE >

TYPE * _LayerRef< TYPE >::get ( ) const

inline

Returns a pointer to the layer, or nullptr if the reference has not yet been matched to a layer.

Definition at line 114 of file qgsmaplayerref.h.

◆ layerMatchesSource()

template<typename TYPE >

bool _LayerRef< TYPE >::layerMatchesSource ( QgsMapLayer * layer ) const

inline

Returns true if a layer matches the weak references to layer public source, layer name and data provider contained in this layer reference.

See also: resolveWeakly()

Definition at line 137 of file qgsmaplayerref.h.

◆ layerMatchesWeakly()

template<typename TYPE >

bool _LayerRef< TYPE >::layerMatchesWeakly	(	QgsMapLayer *	layer,
		MatchType	matchType = `MatchType::All`
	)		const

inline

Definition at line 169 of file qgsmaplayerref.h.

◆ operator bool()

template<typename TYPE >

_LayerRef< TYPE >::operator bool ( ) const

inlineexplicit

Returns true if the layer reference is resolved and contains a reference to an existing map layer.

Definition at line 97 of file qgsmaplayerref.h.

◆ operator->()

template<typename TYPE >

TYPE * _LayerRef< TYPE >::operator-> ( ) const

inline

Forwards the to map layer.

Definition at line 105 of file qgsmaplayerref.h.

◆ operator==()

template<typename TYPE >

bool _LayerRef< TYPE >::operator== ( const _LayerRef< TYPE > & other )

delete

Equality operator is deleted to avoid confusion as there are multiple ways two _LayerRef objects can be considered equal.

◆ readXml()

template<typename TYPE >

bool _LayerRef< TYPE >::readXml	(	const QDomElement &	element,
		const QgsReadWriteContext &	context
	)

inline

Reads the layer's properties from an XML element.

See also: writeXml()

Since: QGIS 3.30

Definition at line 304 of file qgsmaplayerref.h.

◆ resolve()

template<typename TYPE >

TYPE * _LayerRef< TYPE >::resolve ( const QgsProject * project )

inline

Resolves the map layer by attempting to find a layer with matching ID within a project.

If found, this reference will be updated to match the found layer and the layer will be returned. If no matching layer is found, nullptr is returned.

See also: resolveWeakly()

Definition at line 156 of file qgsmaplayerref.h.

◆ resolveByIdOrNameOnly()

template<typename TYPE >

TYPE * _LayerRef< TYPE >::resolveByIdOrNameOnly ( const QgsProject * project )

inline

Resolves the map layer by attempting to find a matching layer in a project using a weak match.

First, the layer is attempted to match to project layers using the layer's ID (calling this method implicitly calls resolve()).

Failing a match by layer ID, the layer will be matched by using the weak references to layer public source, layer name and data provider contained in this layer reference.

Failing a match by weak reference, the layer will be matched by using the name only.

If a matching layer is found, this reference will be updated to match the found layer and the layer will be returned. If no matching layer is found, nullptr is returned.

See also: resolve(); layerMatchesSource(); resolveWeakly()

Since: QGIS 3.8

Definition at line 276 of file qgsmaplayerref.h.

◆ resolveWeakly()

template<typename TYPE >

TYPE * _LayerRef< TYPE >::resolveWeakly	(	const QgsProject *	project,
		MatchType	matchType = `MatchType::All`
	)

inline

Resolves the map layer by attempting to find a matching layer in a project using a weak match.

First, the layer is attempted to match to project layers using the layer's ID (calling this method implicitly calls resolve()).

Failing a match by layer ID, the layer will be matched by using the weak references to layer public source, layer name and data provider contained in this layer reference.

The matchType enum can used to refine the matching criteria when using the weak reference and include layer name, provider name and layer source in the equality test, by default they are all checked.

If a matching layer is found, this reference will be updated to match the found layer and the layer will be returned. If no matching layer is found, nullptr is returned.

See also: resolve(); layerMatchesSource(); layerMatchesWeakly(); resolveByIdOrNameOnly()

Definition at line 217 of file qgsmaplayerref.h.

◆ setLayer()

template<typename TYPE >

void _LayerRef< TYPE >::setLayer ( TYPE * l )

inline

Sets the reference to point to a specified layer.

Definition at line 79 of file qgsmaplayerref.h.

◆ writeXml()

template<typename TYPE >

void _LayerRef< TYPE >::writeXml	(	QDomElement &	element,
		const QgsReadWriteContext &	context
	)		const

inline

Writes the layer's properties to a XML element.

See also: readXml()

Since: QGIS 3.30

Definition at line 321 of file qgsmaplayerref.h.

Member Data Documentation

◆ layer

template<typename TYPE >

QPointer<TYPE> _LayerRef< TYPE >::layer

Weak pointer to map layer.

Definition at line 120 of file qgsmaplayerref.h.

◆ layerId

template<typename TYPE >

QString _LayerRef< TYPE >::layerId

Original layer ID.

Definition at line 123 of file qgsmaplayerref.h.

◆ name

template<typename TYPE >

QString _LayerRef< TYPE >::name

Weak reference to layer name.

Definition at line 128 of file qgsmaplayerref.h.

◆ provider

template<typename TYPE >

QString _LayerRef< TYPE >::provider

Weak reference to layer provider.

Definition at line 130 of file qgsmaplayerref.h.

◆ source

template<typename TYPE >

QString _LayerRef< TYPE >::source

Weak reference to layer public source.

Definition at line 126 of file qgsmaplayerref.h.

The documentation for this struct was generated from the following file:

/build/qgis-3.41.0+git20241122+3440c17df1d+99sid/src/core/qgsmaplayerref.h

Public Types

Public Member Functions

Public Attributes

Detailed Description

Member Enumeration Documentation

◆ MatchType

Constructor & Destructor Documentation

◆ _LayerRef() [1/2]

◆ _LayerRef() [2/2]

Member Function Documentation

◆ get()

◆ layerMatchesSource()

◆ layerMatchesWeakly()

◆ operator bool()

◆ operator->()

◆ operator==()

◆ readXml()

◆ resolve()

◆ resolveByIdOrNameOnly()

◆ resolveWeakly()

◆ setLayer()

◆ writeXml()

Member Data Documentation

◆ layer

◆ layerId

◆ name

◆ provider

◆ source