Main Pal labeling class. More...

#include <pal.h>

Public Types
typedef bool(*	FnIsCanceled) (void *ctx)

Public Member Functions
	Pal ()
	Create an new pal instance. More...

	Pal (const Pal &other)=delete
	Pal cannot be copied. More...

	~Pal ()

Layer *	addLayer (QgsAbstractLabelProvider *provider, const QString &layerName, QgsPalLayerSettings::Placement arrangement, double defaultPriority, bool active, bool toLabel, bool displayAll=false)
	add a new layer More...

std::unique_ptr< Problem >	extractProblem (const QgsRectangle &extent, const QgsGeometry &mapBoundary)
	Extracts the labeling problem for the specified map extent - only features within this extent will be considered. More...

int	getLineP ()
	Returns the number of candidates to generate for line features. More...

int	getPointP ()
	Returns the number of candidates to generate for point features. More...

int	getPolyP ()
	Returns the number of candidates to generate for polygon features. More...

bool	getShowPartial ()
	Returns whether partial labels should be allowed. More...

bool	isCanceled ()
	Check whether the job has been canceled. More...

Pal &	operator= (const Pal &other)=delete
	Pal cannot be copied. More...

void	registerCancellationCallback (FnIsCanceled fnCanceled, void *context)
	Register a function that returns whether this job has been canceled - PAL calls it during the computation. More...

void	removeLayer (Layer *layer)
	remove a layer More...

void	setLineP (int line_p)
	set maximum # candidates to generate for lines features Higher the value is, longer Pal::labeller will spend time More...

void	setPointP (int point_p)
	set # candidates to generate for points features Higher the value is, longer Pal::labeller will spend time More...

void	setPolyP (int poly_p)
	set maximum # candidates to generate for polygon features Higher the value is, longer Pal::labeller will spend time More...

void	setShowPartial (bool show)
	Set flag show partial label. More...

QList< LabelPosition * >	solveProblem (Problem prob, bool displayAll, QList< pal::LabelPosition > *unlabeled=nullptr)
	Solves the labeling problem, selecting the best candidate locations for all labels and returns a list of these calculated label positions. More...

Friends
class	FeaturePart

class	Layer

class	Problem

Detailed Description

Main Pal labeling class.

A pal object will contains layers and global information such as which search method will be used.

Note: not available in Python bindings

Definition at line 87 of file pal.h.

Member Typedef Documentation

◆ FnIsCanceled

typedef bool( * pal::Pal::FnIsCanceled) (void *ctx)

Definition at line 129 of file pal.h.

Constructor & Destructor Documentation

◆ Pal() [1/2]

Pal::Pal ( )

Create an new pal instance.

Definition at line 48 of file pal.cpp.

◆ ~Pal()

Pal::~Pal ( )

Definition at line 68 of file pal.cpp.

◆ Pal() [2/2]

pal::Pal::Pal ( const Pal & other )

delete

Pal cannot be copied.

Member Function Documentation

◆ addLayer()

Layer * Pal::addLayer	(	QgsAbstractLabelProvider *	provider,
		const QString &	layerName,
		QgsPalLayerSettings::Placement	arrangement,
		double	defaultPriority,
		bool	active,
		bool	toLabel,
		bool	displayAll = `false`
	)

add a new layer

Parameters

provider	Provider associated with the layer
layerName	layer's name
arrangement	Howto 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 only if toLablel is `true`
displayAll	if `true`, all features will be labelled even though overlaps occur

Exceptions

PalException::LayerExists

Definition at line 81 of file pal.cpp.

◆ extractProblem()

std::unique_ptr< Problem > Pal::extractProblem	(	const QgsRectangle &	extent,
		const QgsGeometry &	mapBoundary
	)

Extracts the labeling problem for the specified map extent - only features within this extent will be considered.

The mapBoundary argument specifies the actual geometry of the map boundary, which will be used to detect whether a label is visible (or partially visible) in the rendered map. This may differ from extent in the case of rotated or non-rectangular maps.

Definition at line 420 of file pal.cpp.

◆ getLineP()

int Pal::getLineP ( )

Returns the number of candidates to generate for line features.

Definition at line 507 of file pal.cpp.

◆ getPointP()

int Pal::getPointP ( )

Returns the number of candidates to generate for point features.

Definition at line 502 of file pal.cpp.

◆ getPolyP()

int Pal::getPolyP ( )

Returns the number of candidates to generate for polygon features.

Definition at line 512 of file pal.cpp.

◆ getShowPartial()

bool Pal::getShowPartial ( )

Returns whether partial labels should be allowed.

Definition at line 527 of file pal.cpp.

◆ isCanceled()

bool pal::Pal::isCanceled ( )

inline

Check whether the job has been canceled.

Definition at line 135 of file pal.h.

◆ operator=()

Pal& pal::Pal::operator= ( const Pal & other )

delete

Pal cannot be copied.

◆ registerCancellationCallback()

void Pal::registerCancellationCallback	(	Pal::FnIsCanceled	fnCanceled,
		void *	context
	)

Register a function that returns whether this job has been canceled - PAL calls it during the computation.

Definition at line 414 of file pal.cpp.

◆ removeLayer()

void Pal::removeLayer ( Layer * layer )

remove a layer

Parameters

layer layer to remove

Definition at line 54 of file pal.cpp.

◆ setLineP()

void Pal::setLineP ( int line_p )

set maximum # candidates to generate for lines features Higher the value is, longer Pal::labeller will spend time

Parameters

line_p maximum # candidates for a line

Definition at line 451 of file pal.cpp.

◆ setPointP()

void Pal::setPointP ( int point_p )

set # candidates to generate for points features Higher the value is, longer Pal::labeller will spend time

Parameters

point_p # candidates for a point

Definition at line 445 of file pal.cpp.

◆ setPolyP()

void Pal::setPolyP ( int poly_p )

set maximum # candidates to generate for polygon features Higher the value is, longer Pal::labeller will spend time

Parameters

poly_p maximum # candidate for a polygon

Definition at line 457 of file pal.cpp.

◆ setShowPartial()

void Pal::setShowPartial ( bool show )

Set flag show partial label.

Parameters

show	flag value

Definition at line 497 of file pal.cpp.

◆ solveProblem()

QList< LabelPosition * > Pal::solveProblem	(	Problem *	prob,
		bool	displayAll,
		QList< pal::LabelPosition >	unlabeled = `nullptr`
	)

Solves the labeling problem, selecting the best candidate locations for all labels and returns a list of these calculated label positions.

If displayAll is true, then the best positions for ALL labels will be returned, regardless of whether these labels overlap other labels.

If the optional unlabeled list is specified, it will be filled with a list of all feature labels which could not be placed in the returned solution (e.g. due to overlaps or other constraints).

Ownership of the returned labels is not transferred - it resides with the pal object.

Definition at line 425 of file pal.cpp.

Friends And Related Function Documentation

◆ FeaturePart

friend class FeaturePart

friend

Definition at line 90 of file pal.h.

◆ Layer

friend class Layer

friend

Definition at line 91 of file pal.h.

◆ Problem

friend class Problem

friend

Definition at line 89 of file pal.h.

The documentation for this class was generated from the following files:

/build/qgis-3.10.0+15buster/src/core/pal/pal.h
/build/qgis-3.10.0+15buster/src/core/pal/pal.cpp

Public Types

Public Member Functions

Friends

Detailed Description

Member Typedef Documentation

◆ FnIsCanceled

Constructor & Destructor Documentation

◆ Pal() [1/2]

◆ ~Pal()

◆ Pal() [2/2]

Member Function Documentation

◆ addLayer()

◆ extractProblem()

◆ getLineP()

◆ getPointP()

◆ getPolyP()

◆ getShowPartial()

◆ isCanceled()

◆ operator=()

◆ registerCancellationCallback()

◆ removeLayer()

◆ setLineP()

◆ setPointP()

◆ setPolyP()

◆ setShowPartial()

◆ solveProblem()

Friends And Related Function Documentation

◆ FeaturePart

◆ Layer

◆ Problem