This class is a base class for nodes in a layer tree. More...

#include <qgslayertreenode.h>

Inheritance diagram for QgsLayerTreeNode:

Public Types
enum	NodeType { NodeGroup, NodeLayer }
	Enumeration of possible tree node types. More...

Signals
void	addedChildren (QgsLayerTreeNode *node, int indexFrom, int indexTo)
	Emitted when one or more nodes have been added to a node within the tree.
void	customPropertyChanged (QgsLayerTreeNode *node, QString key)
	Emitted when a custom property of a node within the tree has been changed or removed.
void	expandedChanged (QgsLayerTreeNode *node, bool expanded)
	Emitted when the collapsed/expanded state of a node within the tree has been changed.
void	removedChildren (QgsLayerTreeNode *node, int indexFrom, int indexTo)
	Emitted when one or more nodes has been removed from a node within the tree.
void	visibilityChanged (QgsLayerTreeNode *node, Qt::CheckState state)
	Emitted when check state of a node within the tree has been changed.
void	willAddChildren (QgsLayerTreeNode *node, int indexFrom, int indexTo)
	Emitted when one or more nodes will be added to a node within the tree.
void	willRemoveChildren (QgsLayerTreeNode *node, int indexFrom, int indexTo)
	Emitted when one or more nodes will be removed from a node within the tree.

Public Member Functions
	~QgsLayerTreeNode ()
QList< QgsLayerTreeNode * >	children ()
	Get list of children of the node. Children are owned by the parent.
virtual QgsLayerTreeNode *	clone () const =0
	Create a copy of the node. Returns new instance.
QStringList	customProperties () const
	Return list of keys stored in custom properties.
QVariant	customProperty (const QString &key, const QVariant &defaultValue=QVariant()) const
	Read a custom property from layer.
virtual QString	dump () const =0
	Return string with layer tree structure. For debug purposes only.
bool	isExpanded () const
	Return whether the node should be shown as expanded or collapsed in GUI.
NodeType	nodeType ()
	Find out about type of the node. It is usually shorter to use convenience functions from QgsLayerTree namespace for that.
QgsLayerTreeNode *	parent ()
	Get pointer to the parent. If parent is a null pointer, the node is a root node.
void	removeCustomProperty (const QString &key)
	Remove a custom property from layer.
void	setCustomProperty (const QString &key, const QVariant &value)
	Set a custom property for the node.
void	setExpanded (bool expanded)
	Set whether the node should be shown as expanded or collapsed in GUI.
bool	takeChild (QgsLayerTreeNode *node)
	Remove a child from a node.
virtual void	writeXML (QDomElement &parentElement)=0
	Write layer tree to XML.

Static Public Member Functions
static QgsLayerTreeNode *	readXML (QDomElement &element)
	Read layer tree from XML. Returns new instance.

Protected Member Functions
	QgsLayerTreeNode (NodeType t)
	QgsLayerTreeNode (const QgsLayerTreeNode &other)
void	insertChildrenPrivate (int index, QList< QgsLayerTreeNode * > nodes)
	Low-level insertion of children to the node. The children must not have any parent yet!
void	readCommonXML (QDomElement &element)
void	removeChildrenPrivate (int from, int count, bool destroy=true)
	Low-level removal of children from the node.
void	writeCommonXML (QDomElement &element)

Protected Attributes
QList< QgsLayerTreeNode * >	mChildren
	list of children - node is responsible for their deletion
bool	mExpanded
	whether the node should be shown in GUI as expanded
NodeType	mNodeType
	type of the node - determines which subclass is used
QgsLayerTreeNode *	mParent
	pointer to the parent node - null in case of root node
QgsObjectCustomProperties	mProperties
	custom properties attached to the node

Detailed Description

This class is a base class for nodes in a layer tree.

Layer tree is a hierarchical structure consisting of group and layer nodes:

group nodes are containers and may contain children (layer and group nodes)
layer nodes point to map layers, they do not contain further children

Layer trees may be used for organization of layers, typically a layer tree is exposed to the user using QgsLayerTreeView widget which shows the tree and allows manipulation with the tree.

Ownership of nodes: every node is owned by its parent. Therefore once node is added to a layer tree, it is the responsibility of the parent to delete it when the node is not needed anymore. Deletion of root node of a tree will delete all nodes of the tree.

Signals: signals are propagated from children to parent. That means it is sufficient to connect to root node in order to get signals about updates in the whole layer tree. When adding or removing a node that contains further children (i.e. a whole subtree), the addition/removal signals are emitted only for the root node of the subtree that is being added or removed.

Custom properties: Every node may have some custom properties assigned to it. This mechanism allows third parties store additional data with the nodes. The properties are used within QGIS code (whether to show layer in overview, whether the node is embedded from another project etc), but may be also used by third party plugins. Custom properties are stored also in the project file. The storage is not efficient for large amount of data.

Custom properties that have already been used within QGIS:

"loading" - whether the project is being currently loaded (root node only)
"overview" - whether to show a layer in overview
"showFeatureCount" - whether to show feature counts in layer tree (vector only)
"embedded" - whether the node comes from an external project
"embedded_project" - path to the external project (embedded root node only)
"legend/..." - properties for legend appearance customization
"expandedLegendNodes" - list of layer's legend nodes' rules in expanded state

See Also: also QgsLayerTree, QgsLayerTreeLayer, QgsLayerTreeGroup

Note: added in 2.4

Definition at line 65 of file qgslayertreenode.h.

Member Enumeration Documentation

enum QgsLayerTreeNode::NodeType

Enumeration of possible tree node types.

Enumerator:

NodeGroup	container of other groups and layers
NodeLayer	leaf node pointing to a layer

Definition at line 71 of file qgslayertreenode.h.

Constructor & Destructor Documentation

QgsLayerTreeNode::~QgsLayerTreeNode ( )

Definition at line 45 of file qgslayertreenode.cpp.

QgsLayerTreeNode::QgsLayerTreeNode ( QgsLayerTreeNode::NodeType t )

protected

Definition at line 25 of file qgslayertreenode.cpp.

QgsLayerTreeNode::QgsLayerTreeNode ( const QgsLayerTreeNode & other )

protected

Definition at line 32 of file qgslayertreenode.cpp.

Member Function Documentation

void QgsLayerTreeNode::addedChildren	(	QgsLayerTreeNode *	node,
		int	indexFrom,
		int	indexTo
	)

signal

Emitted when one or more nodes have been added to a node within the tree.

QList<QgsLayerTreeNode*> QgsLayerTreeNode::children ( )

inline

Get list of children of the node. Children are owned by the parent.

Definition at line 84 of file qgslayertreenode.h.

virtual QgsLayerTreeNode* QgsLayerTreeNode::clone ( ) const

pure virtual

Create a copy of the node. Returns new instance.

Implemented in QgsLayerTreeGroup, and QgsLayerTreeLayer.

QStringList QgsLayerTreeNode::customProperties ( ) const

Return list of keys stored in custom properties.

Definition at line 95 of file qgslayertreenode.cpp.

QVariant QgsLayerTreeNode::customProperty	(	const QString &	key,
		const QVariant &	defaultValue = `QVariant()`
	)		const

Read a custom property from layer.

Properties are stored in a map and saved in project file.

Definition at line 84 of file qgslayertreenode.cpp.

void QgsLayerTreeNode::customPropertyChanged	(	QgsLayerTreeNode *	node,
		QString	key
	)

signal

Emitted when a custom property of a node within the tree has been changed or removed.

virtual QString QgsLayerTreeNode::dump ( ) const

pure virtual

Return string with layer tree structure. For debug purposes only.

Implemented in QgsLayerTreeGroup, and QgsLayerTreeLayer.

void QgsLayerTreeNode::expandedChanged	(	QgsLayerTreeNode *	node,
		bool	expanded
	)

signal

Emitted when the collapsed/expanded state of a node within the tree has been changed.

void QgsLayerTreeNode::insertChildrenPrivate	(	int	index,
		QList< QgsLayerTreeNode * >	nodes
	)

protected

Low-level insertion of children to the node. The children must not have any parent yet!

Definition at line 111 of file qgslayertreenode.cpp.

bool QgsLayerTreeNode::isExpanded ( ) const

Return whether the node should be shown as expanded or collapsed in GUI.

Definition at line 62 of file qgslayertreenode.cpp.

NodeType QgsLayerTreeNode::nodeType ( )

inline

Find out about type of the node. It is usually shorter to use convenience functions from QgsLayerTree namespace for that.

Definition at line 80 of file qgslayertreenode.h.

QgsLayerTreeNode* QgsLayerTreeNode::parent ( )

inline

Get pointer to the parent. If parent is a null pointer, the node is a root node.

Definition at line 82 of file qgslayertreenode.h.

void QgsLayerTreeNode::readCommonXML ( QDomElement & element )

protected

Definition at line 100 of file qgslayertreenode.cpp.

QgsLayerTreeNode * QgsLayerTreeNode::readXML ( QDomElement & element )

static

Read layer tree from XML. Returns new instance.

Reimplemented in QgsLayerTreeGroup, and QgsLayerTreeLayer.

Definition at line 50 of file qgslayertreenode.cpp.

void QgsLayerTreeNode::removeChildrenPrivate	(	int	from,
		int	count,
		bool	destroy = `true`
	)

protected

Low-level removal of children from the node.

Definition at line 143 of file qgslayertreenode.cpp.

void QgsLayerTreeNode::removeCustomProperty ( const QString & key )

Remove a custom property from layer.

Properties are stored in a map and saved in project file.

Definition at line 89 of file qgslayertreenode.cpp.

void QgsLayerTreeNode::removedChildren	(	QgsLayerTreeNode *	node,
		int	indexFrom,
		int	indexTo
	)

signal

Emitted when one or more nodes has been removed from a node within the tree.

void QgsLayerTreeNode::setCustomProperty	(	const QString &	key,
		const QVariant &	value
	)

Set a custom property for the node.

Properties are stored in a map and saved in project file.

Definition at line 78 of file qgslayertreenode.cpp.

void QgsLayerTreeNode::setExpanded ( bool expanded )

Set whether the node should be shown as expanded or collapsed in GUI.

Definition at line 68 of file qgslayertreenode.cpp.

bool QgsLayerTreeNode::takeChild ( QgsLayerTreeNode * node )

Remove a child from a node.

Definition at line 162 of file qgslayertreenode.cpp.

void QgsLayerTreeNode::visibilityChanged	(	QgsLayerTreeNode *	node,
		Qt::CheckState	state
	)

signal

Emitted when check state of a node within the tree has been changed.

void QgsLayerTreeNode::willAddChildren	(	QgsLayerTreeNode *	node,
		int	indexFrom,
		int	indexTo
	)

signal

Emitted when one or more nodes will be added to a node within the tree.

void QgsLayerTreeNode::willRemoveChildren	(	QgsLayerTreeNode *	node,
		int	indexFrom,
		int	indexTo
	)

signal

Emitted when one or more nodes will be removed from a node within the tree.

void QgsLayerTreeNode::writeCommonXML ( QDomElement & element )

protected

Definition at line 105 of file qgslayertreenode.cpp.

virtual void QgsLayerTreeNode::writeXML ( QDomElement & parentElement )

pure virtual

Write layer tree to XML.

Implemented in QgsLayerTreeGroup, and QgsLayerTreeLayer.

Member Data Documentation

QList<QgsLayerTreeNode*> QgsLayerTreeNode::mChildren

protected

list of children - node is responsible for their deletion

Definition at line 151 of file qgslayertreenode.h.

bool QgsLayerTreeNode::mExpanded

protected

whether the node should be shown in GUI as expanded

Definition at line 153 of file qgslayertreenode.h.

NodeType QgsLayerTreeNode::mNodeType

protected

type of the node - determines which subclass is used

Definition at line 147 of file qgslayertreenode.h.

QgsLayerTreeNode* QgsLayerTreeNode::mParent

protected

pointer to the parent node - null in case of root node

Definition at line 149 of file qgslayertreenode.h.

QgsObjectCustomProperties QgsLayerTreeNode::mProperties

protected

custom properties attached to the node

Definition at line 155 of file qgslayertreenode.h.

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

/tmp/buildd/qgis-2.8.2+12wheezy/src/core/layertree/qgslayertreenode.h
/tmp/buildd/qgis-2.8.2+12wheezy/src/core/layertree/qgslayertreenode.cpp

Public Types

Signals

Public Member Functions

Static Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation