pal::FeaturePart class

Main class to handle feature.

Reference

Base classes

class PointSet

Constructors, destructors, conversion operators

FeaturePart(QgsLabelFeature* lf, const GEOSGeometry* geom): Creates a new generic feature.
~FeaturePart() override: Delete the feature.

Public functions

auto alwaysShow() const -> bool: Returns true if the feature's label should always been shown, even when it collides with other labels.
auto calculatePriority() const -> double: Calculates the priority for the feature.
auto createCandidates(QList<LabelPosition*>& lPos, const GEOSPreparedGeometry* mapBoundary, PointSet* mapShape, RTree<LabelPosition*, double, 2, double>* candidates) -> int: Generic method to generate label candidates for the feature.
auto createCandidatesAlongLine(QList<LabelPosition*>& lPos, PointSet* mapShape) -> int: Generate candidates for line feature.
auto createCandidatesAlongLineNearMidpoint(QList<LabelPosition*>& lPos, PointSet* mapShape, double initialCost = 0.0) -> int: Generate candidates for line feature, by trying to place candidates as close as possible to the line's midpoint.
auto createCandidatesAlongLineNearStraightSegments(QList<LabelPosition*>& lPos, PointSet* mapShape) -> int: Generate candidates for line feature, by trying to place candidates towards the middle of the longest straightish segments of the line.
auto createCandidatesAroundPoint(double x, double y, QList<LabelPosition*>& lPos, double angle) -> int: Generate candidates for point feature, located around a specified point.
auto createCandidatesAtOrderedPositionsOverPoint(double x, double y, QList<LabelPosition*>& lPos, double angle) -> int: Generates candidates following a prioritized list of predefined positions around a point.
auto createCandidatesForPolygon(QList<LabelPosition*>& lPos, PointSet* mapShape) -> int: Generate candidates for polygon features.
auto createCandidatesOverPoint(double x, double y, QList<LabelPosition*>& lPos, double angle) -> int: Generate one candidate over or offset the specified point.
auto createCurvedCandidatesAlongLine(QList<LabelPosition*>& lPos, PointSet* mapShape) -> int: Generate curved candidates for line features.
auto curvedPlacementAtOffset(PointSet* path_positions, double* path_distances, int& orientation, int index, double distance, bool& reversed, bool& flip) -> LabelPosition*: Returns the label position for a curved label at a specific offset along a path.
auto feature() -> QgsLabelFeature*: Returns the parent feature.
auto featureId() const -> QgsFeatureId: Returns the unique ID of the feature.
auto fixedAngle() const -> double: Returns the fixed angle for the feature's label.
auto getNumSelfObstacles() const -> int: Gets number of holes (inner rings) - they are considered as obstacles.
auto getSelfObstacle(int i) -> FeaturePart*: Gets hole (inner ring) - considered as obstacle.
auto hasFixedPosition() const -> bool: Returns true if the feature's label has a fixed position.
auto hasFixedRotation() const -> bool: Returns true if the feature's label has a fixed rotation.
auto hasSameLabelFeatureAs(FeaturePart* part) const -> bool: Tests whether this feature part belongs to the same QgsLabelFeature as another feature part.
auto isConnected(FeaturePart* p2) -> bool: Check whether this part is connected with some other part.
auto isObstacle() const -> bool: Returns true if the feature should act as an obstacle to labels.
auto layer() -> Layer*: Returns the layer that feature belongs to.
auto mergeWithFeaturePart(FeaturePart* other) -> bool: Merge other (connected) part with this one and save the result in this part (other is unchanged).
auto nextCharPosition(double charWidth, double segment_length, PointSet* path_positions, int& index, double& distance, double& start_x, double& start_y, double& end_x, double& end_y) const -> bool: Returns true if the next char position is found. The referenced parameters are updated.
auto obstacleFactor() const -> double: Returns the feature's obstacle factor, which represents the penalty incurred for a label to overlap the feature.
auto repeatDistance() const -> double: Returns the distance between repeating labels for this feature.
auto showUprightLabels() const -> bool: Returns true if feature's label must be displayed upright.

Protected functions

void extractCoords(const GEOSGeometry* geom): read coordinates from a GEOS geom

Function documentation

pal::FeaturePart::FeaturePart(QgsLabelFeature* lf, const GEOSGeometry* geom)

Creates a new generic feature.

Parameters
lf	a pointer for a feature which contains the spatial entites
geom	a pointer to a GEOS geometry

double pal::FeaturePart::calculatePriority() const

Calculates the priority for the feature.

This will be the feature's priority if set, otherwise the layer's default priority.

int pal::FeaturePart::createCandidates(QList<LabelPosition>& lPos, const GEOSPreparedGeometry mapBoundary, PointSet* mapShape, RTree<LabelPosition, double, 2, double> candidates)

Generic method to generate label candidates for the feature.

Parameters
lPos	pointer to an array of candidates, will be filled by generated candidates
mapBoundary	map boundary geometry
mapShape	generate candidates for this spatial entity
candidates	index for candidates
Returns	the number of candidates generated in lPos

int pal::FeaturePart::createCandidatesAlongLine(QList<LabelPosition>& lPos, PointSet mapShape)

Generate candidates for line feature.

Parameters
lPos	pointer to an array of candidates, will be filled by generated candidates
mapShape	a pointer to the line
Returns	the number of generated candidates

int pal::FeaturePart::createCandidatesAlongLineNearMidpoint(QList<LabelPosition>& lPos, PointSet mapShape, double initialCost = 0.0)

Generate candidates for line feature, by trying to place candidates as close as possible to the line's midpoint.

Parameters
lPos	pointer to an array of candidates, will be filled by generated candidates
mapShape	a pointer to the line
initialCost	initial cost for candidates generated using this method. If set, cost can be increased by a preset amount.
Returns	the number of generated candidates

Candidates can "cut corners" if it helps them place near this mid point.

int pal::FeaturePart::createCandidatesAlongLineNearStraightSegments(QList<LabelPosition>& lPos, PointSet mapShape)

Generate candidates for line feature, by trying to place candidates towards the middle of the longest straightish segments of the line.

Parameters
lPos	pointer to an array of candidates, will be filled by generated candidates
mapShape	a pointer to the line
Returns	the number of generated candidates

Segments closer to horizontal are preferred over vertical segments.

int pal::FeaturePart::createCandidatesAroundPoint(double x, double y, QList<LabelPosition*>& lPos, double angle)

Generate candidates for point feature, located around a specified point.

Parameters
x	x coordinate of the point
y	y coordinate of the point
lPos	pointer to an array of candidates, will be filled by generated candidates
angle	orientation of the label
Returns	the number of generated candidates

int pal::FeaturePart::createCandidatesAtOrderedPositionsOverPoint(double x, double y, QList<LabelPosition*>& lPos, double angle)

Generates candidates following a prioritized list of predefined positions around a point.

Parameters
x	x coordinate of the point
y	y coordinate of the point
lPos	pointer to an array of candidates, will be filled by generated candidate
angle	orientation of the label
Returns	the number of generated candidates

int pal::FeaturePart::createCandidatesForPolygon(QList<LabelPosition>& lPos, PointSet mapShape)

Generate candidates for polygon features.

Parameters
lPos	pointer to an array of candidates, will be filled by generated candidates
mapShape	a pointer to the polygon
Returns	the number of generated candidates

int pal::FeaturePart::createCandidatesOverPoint(double x, double y, QList<LabelPosition*>& lPos, double angle)

Generate one candidate over or offset the specified point.

Parameters
x	x coordinate of the point
y	y coordinate of the point
lPos	pointer to an array of candidates, will be filled by generated candidate
angle	orientation of the label
Returns	the number of generated candidates (always 1)

int pal::FeaturePart::createCurvedCandidatesAlongLine(QList<LabelPosition>& lPos, PointSet mapShape)

Generate curved candidates for line features.

Parameters
lPos	pointer to an array of candidates, will be filled by generated candidates
mapShape	a pointer to the line
Returns	the number of generated candidates

LabelPosition* pal::FeaturePart::curvedPlacementAtOffset(PointSet* path_positions, double* path_distances, int& orientation, int index, double distance, bool& reversed, bool& flip)

Returns the label position for a curved label at a specific offset along a path.

Parameters
path_positions	line path to place label on
path_distances	array of distances to each segment on path
orientation	can be 0 for automatic calculation of orientation, or -1/+1 for a specific label orientation
index
distance	distance to offset label along curve by
reversed	if true label is reversed from lefttoright to righttoleft
flip	if true label is placed on the other side of the line
Returns	calculated label position

bool pal::FeaturePart::hasSameLabelFeatureAs(FeaturePart* part) const

Tests whether this feature part belongs to the same QgsLabelFeature as another feature part.

Parameters
part	part to compare to
Returns	true if both parts belong to same QgsLabelFeature

bool pal::FeaturePart::mergeWithFeaturePart(FeaturePart* other)

Merge other (connected) part with this one and save the result in this part (other is unchanged).

Returns true on success, false if the feature wasn't modified