Extension of QgsTracer that provides extra functionality: More...

#include <qgsmapcanvastracer.h>

Inheritance diagram for QgsMapCanvasTracer:

[legend]

Public Member Functions
	QgsMapCanvasTracer (QgsMapCanvas canvas, QgsMessageBar messageBar=nullptr)
	Create tracer associated with a particular map canvas, optionally message bar for reporting.

	~QgsMapCanvasTracer () override

QAction *	actionEnableSnapping () const
	Access to action that user may use to toggle snapping on/off.

QAction *	actionEnableTracing () const
	Access to action that user may use to toggle tracing on/off. May be `nullptr` if no action was associated.

void	reportError (PathError err, bool addingVertex)
	Report a path finding error to the user.

void	setActionEnableSnapping (QAction *action)
	Assign "enable snapping" checkable action to the tracer.

void	setActionEnableTracing (QAction *action)
	Assign "enable tracing" checkable action to the tracer.

Public Member Functions inherited from QgsTracer
	QgsTracer ()
	Constructor for QgsTracer.

	~QgsTracer () override

QgsCoordinateReferenceSystem	destinationCrs () const
	Returns the CRS used for tracing.

QgsRectangle	extent () const
	Gets extent to which graph's features will be limited (empty extent means no limit)

QVector< QgsPointXY >	findShortestPath (const QgsPointXY &p1, const QgsPointXY &p2, PathError *error=nullptr)
	Given two points, find the shortest path and return points on the way.

bool	hasTopologyProblem () const
	Whether there was an error during graph creation due to noding exception, indicating some input data topology problems.

bool	init ()
	Build the internal data structures.

bool	isInitialized () const
	Whether the internal data structures have been initialized.

bool	isPointSnapped (const QgsPointXY &pt)
	Find out whether the point is snapped to a vertex or edge (i.e. it can be used for tracing start/stop)

QList< QgsVectorLayer * >	layers () const
	Gets layers used for tracing.

int	maxFeatureCount () const
	Gets maximum possible number of features in graph. If the number is exceeded, graph is not created.

double	offset () const
	Gets offset in map units that should be applied to the traced paths returned from findShortestPath().

void	offsetParameters (int &quadSegments, int &joinStyle, double &miterLimit)
	Gets extra parameters for offset curve algorithm (used when offset is non-zero)

void	setDestinationCrs (const QgsCoordinateReferenceSystem &crs, const QgsCoordinateTransformContext &context)
	Sets the crs and transform context used for tracing.

void	setExtent (const QgsRectangle &extent)
	Sets extent to which graph's features will be limited (empty extent means no limit)

void	setLayers (const QList< QgsVectorLayer * > &layers)
	Sets layers used for tracing.

void	setMaxFeatureCount (int count)
	Gets maximum possible number of features in graph. If the number is exceeded, graph is not created.

void	setOffset (double offset)
	Set offset in map units that should be applied to the traced paths returned from findShortestPath().

void	setOffsetParameters (int quadSegments, int joinStyle, double miterLimit)
	Set extra parameters for offset curve algorithm (used when offset is non-zero)

void	setRenderContext (const QgsRenderContext *renderContext)
	Sets the renderContext used for tracing only on visible features.

Static Public Member Functions
static QgsMapCanvasTracer *	tracerForCanvas (QgsMapCanvas *canvas)
	Retrieve instance of this class associated with given canvas (if any).

Protected Member Functions
void	configure () override
	Sets configuration from current snapping settings and canvas settings.

Additional Inherited Members
Public Types inherited from QgsTracer
enum	PathError { ErrNone , ErrTooManyFeatures , ErrPoint1 , ErrPoint2 , ErrNoPath }
	Possible errors that may happen when calling findShortestPath() More...

Protected Slots inherited from QgsTracer
void	invalidateGraph ()
	Destroy the existing graph structure if any (de-initialize)

Detailed Description

Extension of QgsTracer that provides extra functionality:

automatic updates of own configuration based on canvas settings
reporting of issues to the user via message bar
determines whether tracing is currently enabled by the user

A simple registry of tracer instances associated to map canvas instances is kept for convenience. (Map tools do not need to create their local tracer instances and map canvas API is not "polluted" by this optional functionality).

Definition at line 40 of file qgsmapcanvastracer.h.

Constructor & Destructor Documentation

◆ QgsMapCanvasTracer()

QgsMapCanvasTracer::QgsMapCanvasTracer	(	QgsMapCanvas *	canvas,
		QgsMessageBar *	messageBar = `nullptr`
	)

explicit

Create tracer associated with a particular map canvas, optionally message bar for reporting.

Definition at line 35 of file qgsmapcanvastracer.cpp.

◆ ~QgsMapCanvasTracer()

QgsMapCanvasTracer::~QgsMapCanvasTracer ( )

override

Definition at line 56 of file qgsmapcanvastracer.cpp.

Member Function Documentation

◆ actionEnableSnapping()

QAction * QgsMapCanvasTracer::actionEnableSnapping ( ) const

inline

Access to action that user may use to toggle snapping on/off.

May be nullptr if no action was associated.

Definition at line 61 of file qgsmapcanvastracer.h.

◆ actionEnableTracing()

QAction * QgsMapCanvasTracer::actionEnableTracing ( ) const

inline

Access to action that user may use to toggle tracing on/off. May be nullptr if no action was associated.

Definition at line 50 of file qgsmapcanvastracer.h.

◆ configure()

void QgsMapCanvasTracer::configure ( )

overrideprotectedvirtual

Sets configuration from current snapping settings and canvas settings.

Reimplemented from QgsTracer.

Definition at line 100 of file qgsmapcanvastracer.cpp.

◆ reportError()

void QgsMapCanvasTracer::reportError	(	QgsTracer::PathError	err,
		bool	addingVertex
	)

Report a path finding error to the user.

Definition at line 66 of file qgsmapcanvastracer.cpp.

◆ setActionEnableSnapping()

void QgsMapCanvasTracer::setActionEnableSnapping ( QAction * action )

inline

Assign "enable snapping" checkable action to the tracer.

The action is used to determine whether snapping is currently enabled by the user.

Definition at line 67 of file qgsmapcanvastracer.h.

◆ setActionEnableTracing()

void QgsMapCanvasTracer::setActionEnableTracing ( QAction * action )

inline

Assign "enable tracing" checkable action to the tracer.

The action is used to determine whether tracing is currently enabled by the user

Definition at line 56 of file qgsmapcanvastracer.h.

◆ tracerForCanvas()

QgsMapCanvasTracer * QgsMapCanvasTracer::tracerForCanvas ( QgsMapCanvas * canvas )

static

Retrieve instance of this class associated with given canvas (if any).

The class keeps a simple registry of tracers associated with map canvas instances for easier access to the common tracer by various map tools

Definition at line 61 of file qgsmapcanvastracer.cpp.

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

/home/fischer/src/qgis-3.38/src/gui/qgsmapcanvastracer.h
/home/fischer/src/qgis-3.38/src/gui/qgsmapcanvastracer.cpp

Public Member Functions

Static Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ QgsMapCanvasTracer()

◆ ~QgsMapCanvasTracer()

Member Function Documentation

◆ actionEnableSnapping()

◆ actionEnableTracing()

◆ configure()

◆ reportError()

◆ setActionEnableSnapping()

◆ setActionEnableTracing()

◆ tracerForCanvas()