Subgroup: Layer
Class: QgsLayerTreeNode¶
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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
checkedLayers
Returns a list of any checked layers which belong to this node or its children. childEvent
children
Get list of children of the node. clone
Create a copy of the node. connectNotify
customEvent
customProperties
Return list of keys stored in custom properties customProperty
Read a custom property from layer. disconnectNotify
dump
Return string with layer tree structure. insertChildrenPrivate
Low-level insertion of children to the node. isExpanded
Return whether the node should be shown as expanded or collapsed in GUI isItemVisibilityCheckedRecursive
Return whether this node is checked and all its children. isItemVisibilityUncheckedRecursive
Return whether this node is unchecked and all its children. isSignalConnected
isVisible
Returns whether a node is really visible (ie checked and all its ancestors checked as well) itemVisibilityChecked
Returns whether a node is checked (independently of its ancestors or children) name
Return name of the node nodeType
Find out about type of the node. parent
Get pointer to the parent. readCommonXml
Read common XML elements. readXml
Read layer tree from XML. receivers
removeChildrenPrivate
Low-level removal of children from the node. removeCustomProperty
Remove a custom property from layer. resolveReferences
Turn textual references to layers into map layer object from project. sender
senderSignalIndex
setCustomProperty
Set a custom property for the node. setExpanded
Set whether the node should be shown as expanded or collapsed in GUI setItemVisibilityChecked
Check or uncheck a node (independently of its ancestors or children) setItemVisibilityCheckedParentRecursive
Check or uncheck a node and all its parents setItemVisibilityCheckedRecursive
Check or uncheck a node and all its children (taking into account exclusion rules) setName
Set name of the node. takeChild
Remove a child from a node timerEvent
writeCommonXml
Write common XML elements. writeXml
Write layer tree to XML Signals
addedChildren
Emitted when one or more nodes have been added to a node within the tree [signal] customPropertyChanged
Emitted when a custom property of a node within the tree has been changed or removed [signal] expandedChanged
Emitted when the collapsed/expanded state of a node within the tree has been changed [signal] nameChanged
Emitted when the name of the node is changed removedChildren
Emitted when one or more nodes has been removed from a node within the tree [signal] visibilityChanged
Emitted when check state of a node within the tree has been changed [signal] willAddChildren
Emitted when one or more nodes will be added to a node within the tree [signal] willRemoveChildren
Emitted when one or more nodes will be removed from a node within the tree [signal] Attributes
NodeGroup
NodeLayer
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NodeGroup
= 0¶
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NodeLayer
= 1¶
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class
NodeType
¶ Bases:
int
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addedChildren
¶ Emitted when one or more nodes have been added to a node within the tree [signal]
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checkedLayers
(self) → List[QgsMapLayer]¶ Returns a list of any checked layers which belong to this node or its children.
New in version 3.0.
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childEvent
()¶
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children
(self) → List[QgsLayerTreeNode]¶ Get list of children of the node. Children are owned by the parent
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clone
(self) → QgsLayerTreeNode¶ Create a copy of the node. Returns new instance
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connectNotify
()¶
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customEvent
()¶
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customProperties
(self) → List[str]¶ Return list of keys stored in custom properties
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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.
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customPropertyChanged
¶ Emitted when a custom property of a node within the tree has been changed or removed [signal]
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disconnectNotify
()¶
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dump
(self) → str¶ Return string with layer tree structure. For debug purposes only
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expandedChanged
¶ Emitted when the collapsed/expanded state of a node within the tree has been changed [signal]
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insertChildrenPrivate
(self, index: int, nodes: Iterable[QgsLayerTreeNode])¶ Low-level insertion of children to the node. The children must not have any parent yet!
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isExpanded
(self) → bool¶ Return whether the node should be shown as expanded or collapsed in GUI
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isItemVisibilityCheckedRecursive
(self) → bool¶ Return whether this node is checked and all its children.
New in version 3.0.
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isItemVisibilityUncheckedRecursive
(self) → bool¶ Return whether this node is unchecked and all its children.
New in version 3.0.
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isSignalConnected
()¶
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isVisible
(self) → bool¶ Returns whether a node is really visible (ie checked and all its ancestors checked as well)
New in version 3.0.
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itemVisibilityChecked
(self) → bool¶ Returns whether a node is checked (independently of its ancestors or children)
New in version 3.0.
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name
(self) → str¶ Return name of the node
New in version 3.0.
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nameChanged
¶ Emitted when the name of the node is changed
New in version 3.0: [signal]
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nodeType
(self) → QgsLayerTreeNode.NodeType¶ Find out about type of the node. It is usually shorter to use convenience functions from QgsLayerTree namespace for that
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parent
(self) → QgsLayerTreeNode¶ Get pointer to the parent. If parent is a null pointer, the node is a root node
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readCommonXml
(self, element: QDomElement)¶ Read common XML elements.
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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 (calls resolveReferences() internally).
New in version 3.0.
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receivers
()¶
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removeChildrenPrivate
(self, from_: int, count: int, destroy: bool = True)¶ Low-level removal of children from the node.
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removeCustomProperty
(self, key: str)¶ Remove a custom property from layer. Properties are stored in a map and saved in project file.
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removedChildren
¶ Emitted when one or more nodes has been removed from a node within the tree [signal]
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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() If
looseMatching
is true 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 customisation from different projects where layers will have different layer IDs.New in version 3.0.
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sender
()¶
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senderSignalIndex
()¶
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setCustomProperty
(self, key: str, value: Any)¶ Set a custom property for the node. Properties are stored in a map and saved in project file.
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setExpanded
(self, expanded: bool)¶ Set whether the node should be shown as expanded or collapsed in GUI
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setItemVisibilityChecked
(self, checked: bool)¶ Check or uncheck a node (independently of its ancestors or children)
New in version 3.0.
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setItemVisibilityCheckedParentRecursive
(self, checked: bool)¶ Check or uncheck a node and all its parents
New in version 3.0.
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setItemVisibilityCheckedRecursive
(self, checked: bool)¶ Check or uncheck a node and all its children (taking into account exclusion rules)
New in version 3.0.
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setName
(self, name: str)¶ Set name of the node. Emits nameChanged signal.
New in version 3.0.
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takeChild
(self, node: QgsLayerTreeNode) → bool¶ Remove a child from a node
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timerEvent
()¶
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visibilityChanged
¶ Emitted when check state of a node within the tree has been changed [signal]
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willAddChildren
¶ Emitted when one or more nodes will be added to a node within the tree [signal]
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willRemoveChildren
¶ Emitted when one or more nodes will be removed from a node within the tree [signal]
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writeCommonXml
(self, element: QDomElement)¶ Write common XML elements.
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writeXml
(self, parentElement: QDomElement, context: QgsReadWriteContext)¶ Write layer tree to XML
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