pal::Layer class

A set of features which influence the labeling process.

Reference

Constructors, destructors, conversion operators

Layer(QgsAbstractLabelProvider* provider, const QString& name, QgsPalLayerSettings::Placement arrangement, double defaultPriority, bool active, bool toLabel, Pal* pal, bool displayAll = false) protected: Create a new layer.

Public functions

auto active() const -> bool: Returns whether the layer is currently active.
auto arrangement() const -> QgsPalLayerSettings::Placement: Returns the layer's arrangement policy.
auto arrangementFlags() const -> LineArrangementFlags: Returns the layer's arrangement flags.
auto centroidInside() const -> bool: Returns whether labels placed at the centroid of features within the layer are forced to be placed inside the feature's geometry.
void chopFeaturesAtRepeatDistance(): Chop layer features at the repeat distance *.
auto connectedFeatureId(QgsFeatureId featureId) const -> int: Returns the connected feature ID for a label feature ID, which is unique for all features which have been joined as a result of joinConnectedFeatures()
auto featureCount() -> int: Returns the number of features in layer.
auto isCurved() const -> bool: Returns true if the layer has curved labels.
void joinConnectedFeatures(): Join connected features with the same label text.
auto labelLayer() const -> bool: Returns whether the layer will be labeled or not.
auto labelMode() const -> LabelMode: Returns the layer's labeling mode.
auto mergeConnectedLines() const -> bool: Returns whether connected lines will be merged before labeling.
auto name() const -> QString: Returns the layer's name.
auto obstacleType() const -> QgsPalLayerSettings::ObstacleType: Returns the obstacle type, which controls how features within the layer act as obstacles for labels.
auto priority() const -> double: Returns the layer's priority, between 0 and 1.
auto provider() const -> QgsAbstractLabelProvider*: Returns pointer to the associated provider.
auto registerFeature(QgsLabelFeature* label) -> bool: Register a feature in the layer.
void setActive(bool active): Sets whether the layer is currently active.
void setArrangement(QgsPalLayerSettings::Placement arrangement): Sets the layer's arrangement policy.
void setArrangementFlags(LineArrangementFlags flags): Sets the layer's arrangement flags.
void setCentroidInside(bool forceInside): Sets whether labels placed at the centroid of features within the layer are forced to be placed inside the feature's geometry.
void setLabelLayer(bool toLabel): Sets whether the layer will be labeled.
void setLabelMode(LabelMode mode): Sets the layer's labeling mode.
void setMergeConnectedLines(bool merge): Sets whether connected lines should be merged before labeling.
void setObstacleType(QgsPalLayerSettings::ObstacleType obstacleType): Sets the obstacle type, which controls how features within the layer act as obstacles for labels.
void setPriority(double priority): Sets the layer's priority.
void setUpsidedownLabels(UpsideDownLabels ud): Sets how upside down labels will be handled within the layer.
auto upsidedownLabels() const -> UpsideDownLabels: Returns how upside down labels are handled within the layer.

Protected functions

void addFeaturePart(FeaturePart* fpart, const QString& labelText = QString()): Add newly created feature part into r tree and to the list.
void addObstaclePart(FeaturePart* fpart): Add newly created obstacle part into r tree and to the list.

Protected variables

QgsPalLayerSettings::Placement mArrangement: Optional flags used for some placement methods.
QLinkedList<FeaturePart*> mFeatureParts: List of feature parts.
QHash<QgsFeatureId, QgsLabelFeature*> mHashtable: Lookup table of label features (owned by the label feature provider that created them)
QList<FeaturePart*> mObstacleParts: List of obstacle parts.

Function documentation

pal::Layer::Layer(QgsAbstractLabelProvider* provider, const QString& name, QgsPalLayerSettings::Placement arrangement, double defaultPriority, bool active, bool toLabel, Pal* pal, bool displayAll = false) protected

Create a new layer.

Parameters
provider	Associated provider
name	Name of the layer (for stats, debugging - does not need to be unique)
arrangement	Arrangement mode : how to place candidates
defaultPriority	layer's prioriry (0 is the best, 1 the worst)
active	is the layer is active (currently displayed)
toLabel	the layer will be labeled whether toLablel is true
pal	pointer to the pal object
displayAll	if true, all features will be labelled even though overlaps occur

bool pal::Layer::active() const

Returns whether the layer is currently active.

QgsPalLayerSettings::Placement pal::Layer::arrangement() const

Returns the layer's arrangement policy.

LineArrangementFlags pal::Layer::arrangementFlags() const

Returns the layer's arrangement flags.

bool pal::Layer::centroidInside() const

Returns whether labels placed at the centroid of features within the layer are forced to be placed inside the feature's geometry.

int pal::Layer::connectedFeatureId(QgsFeatureId featureId) const

Returns the connected feature ID for a label feature ID, which is unique for all features which have been joined as a result of joinConnectedFeatures()

Returns	connected feature ID, or -1 if feature was not joined

bool pal::Layer::labelLayer() const

Returns whether the layer will be labeled or not.

LabelMode pal::Layer::labelMode() const

Returns the layer's labeling mode.

bool pal::Layer::mergeConnectedLines() const

Returns whether connected lines will be merged before labeling.

QgsPalLayerSettings::ObstacleType pal::Layer::obstacleType() const

Returns the obstacle type, which controls how features within the layer act as obstacles for labels.

double pal::Layer::priority() const

Returns the layer's priority, between 0 and 1.

0 corresponds to highest priority, 1 to lowest priority.

bool pal::Layer::registerFeature(QgsLabelFeature* label)

Exceptions
Returns	true on success (i.e. valid geometry)
None

Does not take ownership of the label feature (it is owned by its provider).

void pal::Layer::setActive(bool active)

Sets whether the layer is currently active.

Parameters
active	set to true to make the layer active, or false to deactivate the layer

Active means "is currently displayed or used as obstacles". When a layer is deactivated then feature of this layer will not be used for either labeling or as obstacles.

void pal::Layer::setArrangement(QgsPalLayerSettings::Placement arrangement)

Sets the layer's arrangement policy.

Parameters
arrangement	arrangement policy

void pal::Layer::setArrangementFlags(LineArrangementFlags flags)

Sets the layer's arrangement flags.

Parameters
flags	arrangement flags

void pal::Layer::setCentroidInside(bool forceInside)

Sets whether labels placed at the centroid of features within the layer are forced to be placed inside the feature's geometry.

Parameters
forceInside	set to true to force centroid labels to be within the feature. If set to false then the centroid may fall outside the feature.

void pal::Layer::setLabelLayer(bool toLabel)

Sets whether the layer will be labeled.

Parameters
toLabel	set to false disable labeling this layer

void pal::Layer::setLabelMode(LabelMode mode)

Sets the layer's labeling mode.

Parameters
mode	label mode

void pal::Layer::setMergeConnectedLines(bool merge)

Sets whether connected lines should be merged before labeling.

Parameters
merge	set to true to merge connected lines

void pal::Layer::setObstacleType(QgsPalLayerSettings::ObstacleType obstacleType)

Sets the obstacle type, which controls how features within the layer act as obstacles for labels.

Parameters
obstacleType	new obstacle type

void pal::Layer::setPriority(double priority)

Sets the layer's priority.

Parameters
priority	layer priority, between 0 and 1. 0 corresponds to highest priority, 1 to lowest priority.

void pal::Layer::setUpsidedownLabels(UpsideDownLabels ud)

Sets how upside down labels will be handled within the layer.

Parameters
ud	upside down label handling mode

UpsideDownLabels pal::Layer::upsidedownLabels() const

Returns how upside down labels are handled within the layer.