Class: QgsLayerTree¶

Namespace with helper functions for layer tree operations.

Only generally useful routines should be here. Miscellaneous utility functions for work with the layer tree are in QgsLayerTreeUtils class.

Class Hierarchy¶

Base classes¶

`QgsLayerTreeGroup`	Layer tree group node serves as a container for layers and further groups.
`QgsLayerTreeNode`	Base class for nodes in a layer tree.
QObject

Methods

`clear`	Clear any information from this layer tree.
`customLayerOrder`	The order in which layers will be rendered on the canvas.
`hasCustomLayerOrder`	Determines if the layer order should be derived from the layer tree or if a custom override order shall be used instead.
`layerOrder`	The order in which layers will be rendered on the canvas.
`readLayerOrderFromXml`	Load the layer order from an XML element.
`setCustomLayerOrder`	The order in which layers will be rendered on the canvas.
`setCustomLayerOrderByIds`	The order in which layers will be rendered on the canvas.
`setHasCustomLayerOrder`	Determines if the layer order should be derived from the layer tree or if a custom override order shall be used instead.

Static Methods

`isGroup`	Check whether the node is a valid group node
`isLayer`	Check whether the node is a valid layer node
`readXml`	Load the layer tree from an XML element.

Signals

`customLayerOrderChanged`	Emitted when the custom layer order has changed.
`hasCustomLayerOrderChanged`	Emitted when the hasCustomLayerOrder flag changes.
`layerOrderChanged`	Emitted when the layer order has changed.

class qgis.core.QgsLayerTree[source]¶

Bases: QgsLayerTreeGroup

__init__(): Create a new empty layer tree

clear(self)[source]¶: Clear any information from this layer tree.

customLayerOrder(self) → List[QgsMapLayer]¶

The order in which layers will be rendered on the canvas. Will only be used if the property hasCustomLayerOrder is True. If you need the current layer order that is active, prefer using layerOrder().

See also

setCustomLayerOrder()

See also

layerOrder()

See also

hasCustomLayerOrder()

Return type:: List[QgsMapLayer]

signal customLayerOrderChanged[source]¶: Emitted when the custom layer order has changed.

hasCustomLayerOrder(self) → bool[source]¶

Determines if the layer order should be derived from the layer tree or if a custom override order shall be used instead.

See also

customLayerOrder()

Return type:: bool

signal hasCustomLayerOrderChanged(hasCustomLayerOrder: bool)[source]¶

Emitted when the hasCustomLayerOrder flag changes.

See also

hasCustomLayerOrder()

Parameters:: hasCustomLayerOrder (bool)

static isGroup(node: QgsLayerTreeNode | None) → bool[source]¶

Check whether the node is a valid group node

Parameters:: node (Optional[QgsLayerTreeNode])
Return type:: bool

static isLayer(node: QgsLayerTreeNode | None) → bool[source]¶

Check whether the node is a valid layer node

Parameters:: node (Optional[QgsLayerTreeNode])
Return type:: bool

layerOrder(self) → List[QgsMapLayer]¶

The order in which layers will be rendered on the canvas. Depending on hasCustomLayerOrder, this will return either the override customLayerOrder or the layer order derived from the tree. This property is read only.

See also

customLayerOrder()

Return type:: List[QgsMapLayer]

signal layerOrderChanged[source]¶: Emitted when the layer order has changed.

readLayerOrderFromXml(self, doc: QDomElement)[source]¶

Load the layer order from an XML element. Make sure that this is only called after the layers are loaded.

Parameters:: doc (QDomElement)

static readXml(element: QDomElement, context: QgsReadWriteContext) → QgsLayerTree | None[source]¶

Load the layer tree from an XML element. It is not required that layers are loaded at this point. resolveReferences() needs to be called after loading the layers and before using the tree.

Parameters:

element (QDomElement)
context (QgsReadWriteContext)

Return type:

Optional[QgsLayerTree]

setCustomLayerOrder(self, customLayerOrder: Iterable[QgsMapLayer])[source]¶

The order in which layers will be rendered on the canvas. Will only be used if the property hasCustomLayerOrder is True. If you need the current layer order that is active, prefer using layerOrder().

See also

customLayerOrder()

See also

layerOrder()

See also

hasCustomLayerOrder()

Parameters:: customLayerOrder (Iterable[QgsMapLayer])

setCustomLayerOrderByIds(self, customLayerOrder: Iterable[str | None])¶

The order in which layers will be rendered on the canvas. Will only be used if the property hasCustomLayerOrder is True. If you need the current layer order that is active, prefer using layerOrder().

See also

customLayerOrder()

See also

layerOrder()

See also

hasCustomLayerOrder()