Class: QgsPalLabeling

PAL labeling utilities.

Static Methods

geometryRequiresPreparation	Checks whether a geometry requires preparation before registration with PAL
prepareGeometry	Prepares a geometry for registration with PAL.
splitToGraphemes	Splits a text string to a list of graphemes, which are the smallest allowable character divisions in the string.
splitToLines	Splits a text string to a list of separate lines, using a specified wrap character (wrapCharacter).
staticWillUseLayer	Called to find out whether a specified layer is used for labeling.

class qgis.core.QgsPalLabeling

Bases: object

static geometryRequiresPreparation(geometry: QgsGeometry, context: QgsRenderContext, ct: QgsCoordinateTransform, clipGeometry: QgsGeometry = QgsGeometry(), mergeLines: bool = False) → bool

Checks whether a geometry requires preparation before registration with PAL

Parameters:

• geometry (QgsGeometry) – geometry to prepare

• context (QgsRenderContext) – render context

• ct (QgsCoordinateTransform) – coordinate transform, or invalid transform if no transformation required

• clipGeometry (QgsGeometry = QgsGeometry()) – geometry to clip features to, if applicable

• mergeLines (bool = False) – True if touching lines from this layer will be merged and treated as single features during labeling

Return type:

bool

Returns:

True if geometry requires preparation

static prepareGeometry(geometry: QgsGeometry, context: QgsRenderContext, ct: QgsCoordinateTransform, clipGeometry: QgsGeometry = QgsGeometry(), mergeLines: bool = False) → QgsGeometry

Prepares a geometry for registration with PAL. Handles reprojection, rotation, clipping, etc.

Parameters:

• geometry (QgsGeometry) – geometry to prepare

• context (QgsRenderContext) – render context

• ct (QgsCoordinateTransform) – coordinate transform, or invalid transform if no transformation required

• clipGeometry (QgsGeometry = QgsGeometry()) – geometry to clip features to, if applicable

• mergeLines (bool = False) – True if touching lines from this layer will be merged and treated as single features during labeling

Return type:

QgsGeometry

Returns:

prepared geometry

static splitToGraphemes(text: str | None) → List[str]

Splits a text string to a list of graphemes, which are the smallest allowable character divisions in the string. This accounts for scripts were individual characters are not allowed to be split apart (e.g., Arabic and Indic based scripts)

Parameters:

text (Optional[str]) – string to split

Return type:

List[str]

Returns:

list of graphemes

static splitToLines(text: str | None, wrapCharacter: str | None, autoWrapLength: int = 0, useMaxLineLengthWhenAutoWrapping: bool = True) → List[str]

Splits a text string to a list of separate lines, using a specified wrap character (wrapCharacter). The text string will be split on either newline characters or the wrap character.

Since QGIS 3.4 the autoWrapLength argument can be used to specify an ideal length of line to automatically wrap text to (automatic wrapping is disabled if autoWrapLength is 0). This automatic wrapping is performed after processing wrapping using wrapCharacter. When auto wrapping is enabled, the useMaxLineLengthWhenAutoWrapping argument controls whether the lines should be wrapped to an ideal maximum of autoWrapLength characters, or if False then the lines are wrapped to an ideal minimum length of autoWrapLength characters.

Parameters:

• text (Optional[str])

• wrapCharacter (Optional[str])

• autoWrapLength (int = 0)

• useMaxLineLengthWhenAutoWrapping (bool = True)

Return type:

List[str]

static staticWillUseLayer(layer: QgsMapLayer | None) → bool

Called to find out whether a specified layer is used for labeling.

Parameters:

layer (Optional[QgsMapLayer])

Return type:

bool