QgsMapLayerRegistry Class Reference

This class tracks map layers that are currently loaded and provides a means to fetch a pointer to a map layer and delete it. More...

#include <qgsmaplayerregistry.h>

Signals
void	layersWillBeRemoved (QStringList theLayerIds)
	Emitted when one or more layers are removed from the registry.
void	layerWillBeRemoved (QString theLayerId)
	Emitted when a layer is removed from the registry.
void	layersRemoved (QStringList theLayerIds)
	Emitted after one or more layers were removed from the registry.
void	layerRemoved (QString theLayerId)
	Emitted after a layer was removed from the registry.
void	removeAll ()
	Emitted, when all layers are removed, before layersWillBeRemoved() and layerWillBeRemoved() signals are emitted.
void	layersAdded (QList< QgsMapLayer * > theMapLayers)
	Emitted when one or more layers are added to the registry.
void	layerWasAdded (QgsMapLayer *theMapLayer)
	Emitted when a layer is added to the registry.
void	legendLayersAdded (QList< QgsMapLayer * > theMapLayers)
	Emitted, when a layer is added to the registry and the legend.

Public Member Functions
int	count ()
	Return the number of registered layers.
	~QgsMapLayerRegistry ()
QgsMapLayer *	mapLayer (QString theLayerId)
	Retrieve a pointer to a loaded layer by id.
QList< QgsMapLayer * >	mapLayersByName (QString layerName)
	Retrieve a pointer to a loaded layer by name.
const QMap< QString, QgsMapLayer * > &	mapLayers ()
	Retrieve the mapLayers collection (mainly intended for use by projection)
QList< QgsMapLayer * >	addMapLayers (QList< QgsMapLayer * > theMapLayers, bool addToLegend=true, bool takeOwnership=true)
	Add a list of layers to the map of loaded layers.
QgsMapLayer *	addMapLayer (QgsMapLayer *theMapLayer, bool addToLegend=true, bool takeOwnership=true)
	Add a layer to the map of loaded layers.
void	removeMapLayers (QStringList theLayerIds)
	Remove a set of layers from the registry.
void	removeMapLayer (const QString &theLayerId)
	Remove a layer from qgis.
void	removeAllMapLayers ()
	Remove all registered layers.
Q_DECL_DEPRECATED void	clearAllLayerCaches ()
	Clears all layer caches, resetting them to zero and freeing up any memory they may have been using.
void	reloadAllLayers ()
	Reload all provider data caches (currently used for WFS and WMS providers)

Static Public Member Functions
static QgsMapLayerRegistry *	instance ()
	Returns the instance pointer, creating the object on the first call.

Protected Member Functions
void	connectNotify (const char *signal)
	debugging member invoked when a connect() is made to this object

Detailed Description

This class tracks map layers that are currently loaded and provides a means to fetch a pointer to a map layer and delete it.

Constructor & Destructor Documentation

QgsMapLayerRegistry::~QgsMapLayerRegistry

(

)

Member Function Documentation

QgsMapLayer * QgsMapLayerRegistry::addMapLayer	(	QgsMapLayer *	theMapLayer,
		bool	addToLegend = true,
		bool	takeOwnership = true
	)

Add a layer to the map of loaded layers.

The layersAdded() and layersWasAdded() signals will be emitted in any case. The legendLayersAdded() signal only if addToLegend is true. If you are adding multiple layers at once, you should use addMapLayers() instead.

Parameters

theMapLayer	A layer to add to the registry
addToLegend	If true (by default), the layer will be added to the legend and to the main canvas. If you have a private you can set this parameter to false to hide it.
takeOwnership	Ownership will be transferred to the layer registry. If you specify false here, you have take care of deleting the layer yourself. Not available in python.

Returns

NULL if unable to add layer, otherwise pointer to newly added layer

See Also

addMapLayers

Note

As a side-effect QgsProject is made dirty.

Use addMapLayers if adding more than one layer at a time

takeOwner not available in python binding - always takes ownership

QList< QgsMapLayer * > QgsMapLayerRegistry::addMapLayers	(	QList< QgsMapLayer * >	theMapLayers,
		bool	addToLegend = true,
		bool	takeOwnership = true
	)

Add a list of layers to the map of loaded layers.

The layersAdded() and layersWasAdded() signals will be emitted in any case. The legendLayersAdded() signal only if addToLegend is true.

Parameters

theMapLayers	A list of layer which should be added to the registry
addToLegend	If true (by default), the layers will be added to the legend and to the main canvas. If you have a private layer, you can set this parameter to false to hide it.
takeOwnership	Ownership will be transferred to the layer registry. If you specify false here, you have take care of deleting the layers yourself. Not available in python.

Returns

QList<QgsMapLayer *> - a list of the map layers that were added successfully. If a layer is invalid, or already exists in the registry, it will not be part of the returned QList.

Note

As a side-effect QgsProject is made dirty.

takeOwner not available in python binding - always takes ownership

void QgsMapLayerRegistry::clearAllLayerCaches

(

)

Clears all layer caches, resetting them to zero and freeing up any memory they may have been using.

Layer caches are used to speed up rendering in certain situations see ticket #1974 for more details.

Deprecated:

since 2.4 - does nothing

void QgsMapLayerRegistry::connectNotify ( const char *  signal )

protected

debugging member invoked when a connect() is made to this object

int QgsMapLayerRegistry::count

(

)

Return the number of registered layers.

QgsMapLayerRegistry * QgsMapLayerRegistry::instance ( )

static

Returns the instance pointer, creating the object on the first call.

void QgsMapLayerRegistry::layerRemoved ( QString  theLayerId )

signal

Emitted after a layer was removed from the registry.

Parameters

theLayerId

The id of the layer removed

Note

Consider using layersRemoved() instead

void QgsMapLayerRegistry::layersAdded ( QList< QgsMapLayer * >  theMapLayers )

signal

Emitted when one or more layers are added to the registry.

This signal is also emitted for layers added to the registry, but not to the legend and canvas.

Parameters

theMapLayers

The layers which have been added

See Also

legendLayersAdded()

void QgsMapLayerRegistry::layersRemoved ( QStringList  theLayerIds )

signal

Emitted after one or more layers were removed from the registry.

Parameters

theLayerIds

A list of ids of the layers which were removed.

void QgsMapLayerRegistry::layersWillBeRemoved ( QStringList  theLayerIds )

signal

Emitted when one or more layers are removed from the registry.

Parameters

theLayerIds

A list of ids of the layers which are removed.

void QgsMapLayerRegistry::layerWasAdded ( QgsMapLayer *  theMapLayer )

signal

Emitted when a layer is added to the registry.

Parameters

theMapLayer

The id of the layer which has been added

Note

Consider using layersAdded() instead

void QgsMapLayerRegistry::layerWillBeRemoved ( QString  theLayerId )

signal

Emitted when a layer is removed from the registry.

Parameters

theLayerId

The id of the layer being removed

Note

Consider using layersWillBeRemoved() instead

void QgsMapLayerRegistry::legendLayersAdded ( QList< QgsMapLayer * >  theMapLayers )

signal

Emitted, when a layer is added to the registry and the legend.

Plugins are allowed to have private layers, which are signalled by layersAdded() and layerWasAdded() but will not be advertised by this signal.

Parameters

theMapLayers

The QgsMapLayers which are added to the legend.

QgsMapLayer * QgsMapLayerRegistry::mapLayer

(

QString

theLayerId

)

Retrieve a pointer to a loaded layer by id.

const QMap< QString, QgsMapLayer * > & QgsMapLayerRegistry::mapLayers

(

)

Retrieve the mapLayers collection (mainly intended for use by projection)

QList< QgsMapLayer * > QgsMapLayerRegistry::mapLayersByName

(

QString

layerName

)

Retrieve a pointer to a loaded layer by name.

void QgsMapLayerRegistry::reloadAllLayers

(

)

Reload all provider data caches (currently used for WFS and WMS providers)

void QgsMapLayerRegistry::removeAll ( )

signal

Emitted, when all layers are removed, before layersWillBeRemoved() and layerWillBeRemoved() signals are emitted.

You will still get these signals in any case. You can use this signal to do easy (and fast) cleanup.

void QgsMapLayerRegistry::removeAllMapLayers

(

)

Remove all registered layers.

Note

As a side-effect QgsProject is made dirty.

The layers are deleted as the registry is cleared!

void QgsMapLayerRegistry::removeMapLayer

(

const QString &

theLayerId

)

Remove a layer from qgis.

Any canvases using the affected layers will need to remove them

The layer being removed is deleted as well as the registry table entry.

Parameters

theLayerId

The id of the layer to remove

Note

As a side-effect QgsProject is made dirty.

void QgsMapLayerRegistry::removeMapLayers

(

QStringList

theLayerIds

)

Remove a set of layers from the registry.

Any canvases using the affected layers will need to remove them

The layers being removed are deleted as well as the registry table entries.

Parameters

theLayerIds

The ids of the layers to remove

Note

As a side-effect QgsProject is made dirty.

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

• /tmp/buildd/qgis-2.6.0+wheezy1/src/core/qgsmaplayerregistry.h
• /tmp/buildd/qgis-2.6.0+wheezy1/src/core/qgsmaplayerregistry.cpp