Class: QgsLayerTreeModelLegendNode

The QgsLegendRendererItem class is abstract interface for legend items returned from QgsMapLayerLegend implementation.

The objects are used in QgsLayerTreeModel. Custom implementations may offer additional interactivity and customized look.

Class Hierarchy

Inheritance diagram of qgis.core.QgsLayerTreeModelLegendNode

Base classes

QObject

Subclasses

QgsColorRampLegendNode

A legend node which renders a color ramp.

QgsDataDefinedSizeLegendNode

Produces legend node with a marker symbol

QgsImageLegendNode

Implementation of legend node interface for displaying arbitrary raster

QgsRasterSymbolLegendNode

Implementation of legend node interface for displaying raster legend

QgsSimpleLegendNode

Implementation of legend node interface for displaying arbitrary label with icon.

QgsSymbolLegendNode

Implementation of legend node interface for displaying preview of vector symbols and their labels and allowing interaction with the symbol / renderer.

QgsVectorLabelLegendNode

Produces legend node for a labeling text symbol

QgsWmsLegendNode

Implementation of legend node interface for displaying WMS legend
class qgis.core.QgsLayerTreeModelLegendNode[source]

Bases: QObject

__init__(nodeL: QgsLayerTreeLayer | None, parent: QObject | None = None)

Construct the node with pointer to its parent layer node

Parameters:
ColorRampLegend = 7
class CustomRole(*values)

Bases: IntEnum

Legend node data roles

Note

Prior to QGIS 3.36 this was available as QgsLayerTreeModelLegendNode.LegendNodeRoles

Added in version 3.36.

  • RuleKey: Rule key of the node (QString)

    Available as QgsLayerTreeModelLegendNode.RuleKeyRole in older QGIS releases.

  • ParentRuleKey: Rule key of the parent legend node - for legends with tree hierarchy (QString). Added in 2.8

    Available as QgsLayerTreeModelLegendNode.ParentRuleKeyRole in older QGIS releases.

  • NodeType: Type of node. Added in 3.16

    Available as QgsLayerTreeModelLegendNode.NodeTypeRole in older QGIS releases.

  • IsDataDefinedSize: Set when a node is related to data defined size (title or separated legend items). Added in 3.38

    Available as QgsLayerTreeModelLegendNode.IsDataDefinedSizeRole in older QGIS releases.

DataDefinedSizeLegend = 5
EmbeddedWidget = 6
ImageLegend = 3
class ItemContext
class ItemContext(a0: QgsLayerTreeModelLegendNode.ItemContext)

Bases: object

columnLeft
columnRight
context
labelXOffset
maxSiblingSymbolWidth
painter
patchShape
patchSize
point
screenProperties
textDocument
textDocumentMetrics
top
class ItemMetrics
class ItemMetrics(a0: QgsLayerTreeModelLegendNode.ItemMetrics)

Bases: object

labelSize
symbolSize
LegendNodeRoles

alias of CustomRole

class NodeTypes

Bases: int

RasterSymbolLegend = 2
SimpleLegend = 0
SymbolLegend = 1
WmsLegend = 4
checkAllItems(self)[source]

Checks all checkable items belonging to the same layer as this node.

See also

uncheckAllItems()

See also

toggleAllItems()

Added in version 3.18.

columnBreak(self) → bool[source]

Returns whether a forced column break should occur before the node.

See also

setColumnBreak()

Added in version 3.14.

Return type:

bool

createTemporaryRenderContext(self) → QgsRenderContext | None[source]

Returns a temporary context or None if legendMapViewData are not valid

Return type:

Optional[QgsRenderContext]

data(self, role: int) → Any[source]

Returns data associated with the item. Must be implemented in derived class.

Parameters:

role (int)

Return type:

Any

signal dataChanged[source]

pyqtSignal(*types, name: str = …, revision: int = …, arguments: Sequence = …) -> PYQT_SIGNAL

types is normally a sequence of individual types. Each type is either a type object or a string that is the name of a C++ type. Alternatively each type could itself be a sequence of types each describing a different overloaded signal. name is the optional C++ name of the signal. If it is not specified then the name of the class attribute that is bound to the signal is used. revision is the optional revision of the signal that is exported to QML. If it is not specified then 0 is used. arguments is the optional sequence of the names of the signal’s arguments.

draw(self, settings: QgsLegendSettings, ctx: QgsLayerTreeModelLegendNode.ItemContext | None) → QgsLayerTreeModelLegendNode.ItemMetrics[source]

Entry point called from QgsLegendRenderer to do the rendering. Default implementation calls drawSymbol() and drawSymbolText() methods.

If ctx is None, this is just first stage when preparing layout - without actual rendering.

Parameters:
Return type:

QgsLayerTreeModelLegendNode.ItemMetrics

drawSymbol(self, settings: QgsLegendSettings, ctx: QgsLayerTreeModelLegendNode.ItemContext | None, itemHeight: float) → QSizeF[source]

Draws symbol on the left side of the item

Parameters:

  • settings (QgsLegendSettings) – Legend layout configuration

  • ctx (Optional[QgsLayerTreeModelLegendNode.ItemContext]) – Context for rendering - may be None if only doing layout without actual rendering

  • itemHeight (float) – Minimal height of the legend item - used for correct positioning when rendering

Return type:

QSizeF

Returns:

Real size of the symbol (may be bigger than “normal” symbol size from settings)

drawSymbolText(self, settings: QgsLegendSettings, ctx: QgsLayerTreeModelLegendNode.ItemContext | None, symbolSize: QSizeF) → QSizeF[source]

Draws label on the right side of the item

Parameters:

  • settings (QgsLegendSettings) – Legend layout configuration

  • ctx (Optional[QgsLayerTreeModelLegendNode.ItemContext]) – Context for rendering - may be None if only doing layout without actual rendering

  • symbolSize (QSizeF) – Real size of the associated symbol - used for correct positioning when rendering

Return type:

QSizeF

Returns:

Size of the label (may span multiple lines)

exportSymbolToJson(self, settings: QgsLegendSettings, context: QgsRenderContext) → Dict[str, QJsonValue][source]

Adds a symbol in base64 string within a JSON object with the key “icon”.

Parameters:

Added in version 3.8.

Return type:

Dict[str, QJsonValue]

exportToJson(self, settings: QgsLegendSettings, context: QgsRenderContext) → Dict[str, QJsonValue][source]

Entry point called from QgsLegendRenderer to do the rendering in a JSON object.

Parameters:

Added in version 3.8.

Return type:

Dict[str, QJsonValue]

flags(self) → Qt.ItemFlags[source]

Returns item flags associated with the item. Default implementation returns Qt.ItemIsEnabled.

Return type:

Qt.ItemFlags

invalidateMapBasedData(self)[source]

Notification from model that information from associated map view has changed. Default implementation does nothing.

isEmbeddedInParent(self) → bool[source]
Return type:

bool

isScaleOK(self, scale: float) → bool[source]
Parameters:

scale (float)

Return type:

bool

layerNode(self) → QgsLayerTreeLayer | None[source]

Returns pointer to the parent layer node

Return type:

Optional[QgsLayerTreeLayer]

model(self) → QgsLayerTreeModel | None[source]

Returns pointer to model owning this legend node

Return type:

Optional[QgsLayerTreeModel]

setColumnBreak(self, breakBeforeNode: bool)[source]

Sets whether a forced column break should occur before the node.

See also

columnBreak()

Added in version 3.14.

Parameters:

breakBeforeNode (bool)

setData(self, value: Any, role: int) → bool[source]

Sets some data associated with the item. Default implementation does nothing and returns False.

Parameters:

  • value (Any)

  • role (int)

Return type:

bool

setEmbeddedInParent(self, embedded: bool)[source]
Parameters:

embedded (bool)

setUserLabel(self, userLabel: str | None)[source]
Parameters:

userLabel (Optional[str])

setUserPatchSize(self, size: QSizeF)[source]

Sets the user (overridden) size for the legend node.

If either the width or height are non-zero, they will be used when rendering the legend node instead of the default symbol width or height from QgsLegendSettings.

See also

userPatchSize()

Added in version 3.14.

Parameters:

size (QSizeF)

signal sizeChanged[source]

pyqtSignal(*types, name: str = …, revision: int = …, arguments: Sequence = …) -> PYQT_SIGNAL

types is normally a sequence of individual types. Each type is either a type object or a string that is the name of a C++ type. Alternatively each type could itself be a sequence of types each describing a different overloaded signal. name is the optional C++ name of the signal. If it is not specified then the name of the class attribute that is bound to the signal is used. revision is the optional revision of the signal that is exported to QML. If it is not specified then 0 is used. arguments is the optional sequence of the names of the signal’s arguments.

toggleAllItems(self)[source]

Toggle all checkable items belonging to the same layer as this node.

See also

checkAllItems()

See also

uncheckAllItems()

Added in version 3.18.

uncheckAllItems(self)[source]

Unchecks all checkable items belonging to the same layer as this node.

See also

checkAllItems()

See also

toggleAllItems()

Added in version 3.18.

userLabel(self) → str[source]
Return type:

str

userPatchSize(self) → QSizeF[source]

Returns the user (overridden) size for the legend node.

If either the width or height are non-zero, they will be used when rendering the legend node instead of the default symbol width or height from QgsLegendSettings.

See also

setUserPatchSize()

Added in version 3.14.

Return type:

QSizeF