Class: QgsLayerTreeNode¶
- class qgis.core.QgsLayerTreeNode(t: QgsLayerTreeNode.NodeType, checked: bool = True)¶
Bases:
PyQt5.QtCore.QObject
Constructor
QgsLayerTreeNode(other:
QgsLayerTreeNode
)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()
New in version 2.4:
Methods
Returns a list of any checked layers which belong to this node or its children.
Gets list of children of the node.
Create a copy of the node.
Returns list of keys stored in custom properties
Read a custom property from layer.
Returns the depth of this node, i.e. the number of its ancestors.
Returns string with layer tree structure.
Low-level insertion of children to the node.
Returns whether the node should be shown as expanded or collapsed in GUI
Returns whether this node is checked and all its children.
Returns whether this node is unchecked and all its children.
Returns whether a node is really visible (ie checked and all its ancestors checked as well)
Returns whether a node is checked (independently of its ancestors or children)
Returns name of the node
Find out about type of the node.
Gets pointer to the parent.
Read common XML elements.
Read layer tree from XML.
Low-level removal of children from the node.
Remove a custom property from layer.
Turn textual references to layers into map layer object from project.
Sets a custom property for the node.
Sets whether the node should be shown as expanded or collapsed in GUI
Check or uncheck a node (independently of its ancestors or children)
Check or uncheck a node and all its parents
Check or uncheck a node and all its children (taking into account exclusion rules)
Set name of the node.
Remove a child from a node
Write common XML elements.
Write layer tree to XML
Signals
Emitted when one or more nodes have been added to a node within the tree [signal]
Emitted when a custom property of a node within the tree has been changed or removed [signal]
Emitted when the collapsed/expanded state of a node within the tree has been changed [signal]
Emitted when the name of the node is changed
Emitted when one or more nodes has been removed from a node within the tree [signal]
Emitted when check state of a node within the tree has been changed [signal]
Emitted when one or more nodes will be added to a node within the tree [signal]
Emitted when one or more nodes will be removed from a node within the tree [signal]
Attributes
- NodeGroup = 0¶
- NodeLayer = 1¶
- class NodeType¶
Bases:
int
- addedChildren¶
Emitted when one or more nodes have been added to a node within the tree [signal]
- Parameters
node (QgsLayerTreeNode) –
indexFrom (int) –
indexTo (int) –
- checkedLayers(self) List[QgsMapLayer] ¶
Returns a list of any checked layers which belong to this node or its children.
New in version 3.0.
- Return type
List[QgsMapLayer]
- childEvent(self, QChildEvent)¶
- children(self) List[QgsLayerTreeNode] ¶
Gets list of children of the node. Children are owned by the parent
- Return type
List[QgsLayerTreeNode]
- clone(self) QgsLayerTreeNode ¶
Create a copy of the node. Returns new instance
- Return type
- connectNotify(self, QMetaMethod)¶
- customEvent(self, QEvent)¶
- customProperties(self) List[str] ¶
Returns list of keys stored in custom properties
- Return type
List[str]
- customProperty(self, key: str, defaultValue: Any = None) Any ¶
Read a custom property from layer. Properties are stored in a map and saved in project file.
- Parameters
key (str) –
defaultValue (Any = None) –
- Return type
Any
- customPropertyChanged¶
Emitted when a custom property of a node within the tree has been changed or removed [signal]
- Parameters
node (QgsLayerTreeNode) –
key (str) –
- depth(self) int ¶
Returns the depth of this node, i.e. the number of its ancestors
New in version 3.14.
- Return type
int
- disconnectNotify(self, QMetaMethod)¶
- dump(self) str ¶
Returns string with layer tree structure. For debug purposes only
- Return type
str
- expandedChanged¶
Emitted when the collapsed/expanded state of a node within the tree has been changed [signal]
- Parameters
node (QgsLayerTreeNode) –
expanded (bool) –
- insertChildrenPrivate(self, index: int, nodes: Iterable[QgsLayerTreeNode])¶
Low-level insertion of children to the node. The children must not have any parent yet!
- Parameters
index (int) –
nodes (Iterable[QgsLayerTreeNode]) –
- isExpanded(self) bool ¶
Returns whether the node should be shown as expanded or collapsed in GUI
- Return type
bool
- isItemVisibilityCheckedRecursive(self) bool ¶
Returns whether this node is checked and all its children.
New in version 3.0.
- Return type
bool
- isItemVisibilityUncheckedRecursive(self) bool ¶
Returns whether this node is unchecked and all its children.
New in version 3.0.
- Return type
bool
- isSignalConnected(self, QMetaMethod) bool ¶
- isVisible(self) bool ¶
Returns whether a node is really visible (ie checked and all its ancestors checked as well)
New in version 3.0.
- Return type
bool
- itemVisibilityChecked(self) bool ¶
Returns whether a node is checked (independently of its ancestors or children)
New in version 3.0.
- Return type
bool
- name(self) str ¶
Returns name of the node
New in version 3.0.
- Return type
str
- nameChanged¶
Emitted when the name of the node is changed
New in version 3.0: [signal]
- Parameters
node (QgsLayerTreeNode) –
name (str) –
- nodeType(self) QgsLayerTreeNode.NodeType ¶
Find out about type of the node. It is usually shorter to use convenience functions from
QgsLayerTree
namespace for that- Return type
- parent(self) QgsLayerTreeNode ¶
Gets pointer to the parent. If parent is
None
, the node is a root node- Return type
- readCommonXml(self, element: QDomElement)¶
Read common XML elements.
- Parameters
element (QDomElement) –
- readXml(element: QDomElement, context: QgsReadWriteContext) QgsLayerTreeNode ¶
Read layer tree from XML. Returns new instance. Does not resolve textual references to layers. Call
resolveReferences()
afterwards to do it.readXml(element: QDomElement, project:
QgsProject
) -> QgsLayerTreeNode Read layer tree from XML. Returns new instance. Also resolves textual references to layers from the project (callsresolveReferences()
internally).New in version 3.0.
- Parameters
element (QDomElement) –
context (QgsReadWriteContext) –
- Return type
- receivers(self, PYQT_SIGNAL) int ¶
- removeChildrenPrivate(self, from_: int, count: int, destroy: bool = True)¶
Low-level removal of children from the node.
- Parameters
from (int) –
count (int) –
destroy (bool = True) –
- removeCustomProperty(self, key: str)¶
Remove a custom property from layer. Properties are stored in a map and saved in project file.
- Parameters
key (str) –
- removedChildren¶
Emitted when one or more nodes has been removed from a node within the tree [signal]
- Parameters
node (QgsLayerTreeNode) –
indexFrom (int) –
indexTo (int) –
- resolveReferences(self, project: QgsProject, looseMatching: bool = False)¶
Turn textual references to layers into map layer object from project. This method should be called after
readXml()
IflooseMatching
isTrue
then a looser match will be used, where a layer will match if the name, public source, and data provider match. This can be used to match legend customization from different projects where layers will have different layer IDs.New in version 3.0.
- Parameters
project (QgsProject) –
looseMatching (bool = False) –
- sender(self) QObject ¶
- senderSignalIndex(self) int ¶
- setCustomProperty(self, key: str, value: Any)¶
Sets a custom property for the node. Properties are stored in a map and saved in project file.
- Parameters
key (str) –
value (Any) –
- setExpanded(self, expanded: bool)¶
Sets whether the node should be shown as expanded or collapsed in GUI
- Parameters
expanded (bool) –
- setItemVisibilityChecked(self, checked: bool)¶
Check or uncheck a node (independently of its ancestors or children)
See also
QgsLayerTreeView.setLayerVisible()
New in version 3.0.
- Parameters
checked (bool) –
- setItemVisibilityCheckedParentRecursive(self, checked: bool)¶
Check or uncheck a node and all its parents
New in version 3.0.
- Parameters
checked (bool) –
- setItemVisibilityCheckedRecursive(self, checked: bool)¶
Check or uncheck a node and all its children (taking into account exclusion rules)
New in version 3.0.
- Parameters
checked (bool) –
- setName(self, name: str)¶
Set name of the node. Emits nameChanged signal.
New in version 3.0.
- Parameters
name (str) –
- takeChild(self, node: QgsLayerTreeNode) bool ¶
Remove a child from a node
- Parameters
node (QgsLayerTreeNode) –
- Return type
bool
- timerEvent(self, QTimerEvent)¶
- visibilityChanged¶
Emitted when check state of a node within the tree has been changed [signal]
- Parameters
node (QgsLayerTreeNode) –
- willAddChildren¶
Emitted when one or more nodes will be added to a node within the tree [signal]
- Parameters
node (QgsLayerTreeNode) –
indexFrom (int) –
indexTo (int) –
- willRemoveChildren¶
Emitted when one or more nodes will be removed from a node within the tree [signal]
- Parameters
node (QgsLayerTreeNode) –
indexFrom (int) –
indexTo (int) –
- writeCommonXml(self, element: QDomElement)¶
Write common XML elements.
- Parameters
element (QDomElement) –
- writeXml(self, parentElement: QDomElement, context: QgsReadWriteContext)¶
Write layer tree to XML
- Parameters
parentElement (QDomElement) –
context (QgsReadWriteContext) –