Class: QgsCallout

class qgis.core.QgsCallout

Bases: sip.wrapper

Constructor for QgsCallout.

QgsCallout(QgsCallout)

Abstract base class for callout renderers.

Implementations of QgsCallout are responsible for performing the actual render of callouts, including determining the desired shape of the callout and using any relevant symbology elements to render them.

New in version 3.10: Enums

Methods

anchorPoint

Returns the feature’s anchor point position.

clone

Duplicates a callout by creating a deep copy of the callout.

dataDefinedProperties

Returns a reference to the callout’s property collection, used for data defined overrides.

decodeAnchorPoint

Attempts to decode a string representation of an anchor point name to the corresponding anchor point.

draw

Performs the actual rendering of the callout implementation onto the specified render context.

drawOrder

Returns the desired drawing order (stacking) to use while rendering this callout.

enabled

Returns True if the the callout is enabled.

encodeAnchorPoint

Encodes an anchor point to its string representation.

properties

Returns the properties describing the callout encoded in a string format.

propertyDefinitions

Returns the definitions for data defined properties available for use in callouts.

readProperties

Reads a string map of an callout’s properties and restores the callout to the state described by the properties map.

referencedFields

Returns the set of attributes referenced by the callout.

render

Renders the callout onto the specified render context.

restoreProperties

Restores the callout’s properties from a DOM element.

saveProperties

Saves the current state of the callout to a DOM element.

setAnchorPoint

Sets the feature’s anchor point position.

setDataDefinedProperties

Sets the callout’s property collection, used for data defined overrides.

setEnabled

Sets whether the callout is enabled.

startRender

Prepares the callout for rendering on the specified render context.

stopRender

Finalises the callout after a set of rendering operations on the specified render context.

type

Returns a unique string representing the callout type.

Signals

Attributes

AnchorPointPosition

Centroid

DrawCalloutToAllParts

MinimumCalloutLength

OffsetFromAnchor

OffsetFromLabel

OrderBelowAllLabels

OrderBelowIndividualLabels

PointOnExterior

PointOnSurface

PoleOfInaccessibility

class AnchorPoint

Bases: int

AnchorPointPosition = 4
Centroid = 3
DrawCalloutToAllParts = 3
class DrawOrder

Bases: int

MinimumCalloutLength = 0
OffsetFromAnchor = 1
OffsetFromLabel = 2
OrderBelowAllLabels = 0
OrderBelowIndividualLabels = 1
PointOnExterior = 1
PointOnSurface = 2
PoleOfInaccessibility = 0
class Property

Bases: int

class QgsCalloutContext

Bases: sip.wrapper

QgsCallout.QgsCalloutContext(QgsCallout.QgsCalloutContext)

allFeaturePartsLabeled
anchorPoint(self) → QgsCallout.AnchorPoint

Returns the feature’s anchor point position.

See also

setAnchorPoint()

clone(self) → QgsCallout

Duplicates a callout by creating a deep copy of the callout.

Caller takes ownership of the returned object.

dataDefinedProperties(self) → QgsPropertyCollection

Returns a reference to the callout’s property collection, used for data defined overrides.

decodeAnchorPoint(name: str) → Tuple[QgsCallout.AnchorPoint, bool]

Attempts to decode a string representation of an anchor point name to the corresponding anchor point.

Parameters
  • name – encoded anchor point name

  • ok – if specified, will be set to True if the anchor point was successfully decoded

Returns

decoded name

draw(self, context: QgsRenderContext, bodyBoundingBox: QRectF, angle: float, anchor: QgsGeometry, calloutContext: QgsCallout.QgsCalloutContext)

Performs the actual rendering of the callout implementation onto the specified render context.

The bodyBoundingBox argument gives the desired size and position of the body of the callout (e.g. the actual label geometry). The angle argument specifies the rotation of the callout body (in degrees clockwise from horizontal). It is assumed that angle rotation specified via angle is applied around the center of rect.

The anchor argument dictates the geometry which the callout should connect to. Depending on the callout subclass and anchor geometry type, the actual shape of the rendered callout may vary. E.g. a subclass may prefer to attach to the centroid of the anchor, while another subclass may prefer to attach to the closest point on anchor instead.

Both rect and anchor are specified in painter coordinates (i.e. pixels).

The calloutContext argument is used to specify additional contextual information about how a callout is being rendered.

drawOrder(self) → QgsCallout.DrawOrder

Returns the desired drawing order (stacking) to use while rendering this callout.

The default order is QgsCallout.OrderBelowIndividualLabels.

enabled(self) → bool

Returns True if the the callout is enabled.

See also

setEnabled()

encodeAnchorPoint(anchor: QgsCallout.AnchorPoint) → str

Encodes an anchor point to its string representation.

Returns

encoded string

properties(self, context: QgsReadWriteContext) → Dict[str, Any]

Returns the properties describing the callout encoded in a string format.

Subclasses must ensure that they include the base class’ properties() in their returned value.

See also

readProperties()

See also

saveProperties()

propertyDefinitions() → Dict[int, QgsPropertyDefinition]

Returns the definitions for data defined properties available for use in callouts.

readProperties(self, props: Dict[str, Any], context: QgsReadWriteContext)

Reads a string map of an callout’s properties and restores the callout to the state described by the properties map.

Subclasses must ensure that they call the base class’ readProperties() method.

See also

properties()

referencedFields(self, context: QgsRenderContext) → Set[str]

Returns the set of attributes referenced by the callout. This includes attributes required by any data defined properties associated with the callout.

Warning

This must only be called after a corresponding call to startRender() with the same render context.

render(self, context: QgsRenderContext, rect: QRectF, angle: float, anchor: QgsGeometry, calloutContext: QgsCallout.QgsCalloutContext)

Renders the callout onto the specified render context.

The rect argument gives the desired size and position of the body of the callout (e.g. the actual label geometry). The angle argument specifies the rotation of the callout body (in degrees clockwise from horizontal). It is assumed that angle rotation specified via angle is applied around the center of rect.

The anchor argument dictates the geometry which the callout should connect to. Depending on the callout subclass and anchor geometry type, the actual shape of the rendered callout may vary. E.g. a subclass may prefer to attach to the centroid of the anchor, while another subclass may prefer to attach to the closest point on anchor instead.

Both rect and anchor must be specified in painter coordinates (i.e. pixels).

The calloutContext argument is used to specify additional contextual information about how a callout is being rendered.

Warning

A prior call to startRender() must have been made before calling this method, and after all render() operations are complete a call to stopRender() must be made.

restoreProperties(self, element: QDomElement, context: QgsReadWriteContext)

Restores the callout’s properties from a DOM element.

The default behavior is the read the DOM contents and call readProperties() on the subclass.

See also

readProperties()

saveProperties(self, doc: QDomDocument, element: QDomElement, context: QgsReadWriteContext) → bool

Saves the current state of the callout to a DOM element. The default behavior is to save the properties string map returned by properties().

Returns

True if save was successful

See also

readProperties()

setAnchorPoint(self, anchor: QgsCallout.AnchorPoint)

Sets the feature’s anchor point position.

See also

anchorPoint()

setDataDefinedProperties(self, collection: QgsPropertyCollection)

Sets the callout’s property collection, used for data defined overrides.

Any existing properties will be discarded.

See also

Property

setEnabled(self, enabled: bool)

Sets whether the callout is enabled.

See also

enabled()

startRender(self, context: QgsRenderContext)

Prepares the callout for rendering on the specified render context.

Warning

This MUST be called prior to calling render() on the callout, and must always be accompanied by a corresponding call to stopRender().

See also

stopRender()

stopRender(self, context: QgsRenderContext)

Finalises the callout after a set of rendering operations on the specified render context.

Warning

This MUST be called after to after render() operations on the callout, and must always be accompanied by a corresponding prior call to startRender().

See also

startRender()

type(self) → str

Returns a unique string representing the callout type.