Does vector analysis using the geos library and handles import, export, exception handling*. More...

#include <qgsgeos.h>

Inheritance diagram for QgsGeos:

Public Member Functions
	QgsGeos (const QgsAbstractGeometry *geometry, double precision=0)
	GEOS geometry engine constructor. More...

double	area (QString *errorMsg=nullptr) const override

QgsAbstractGeometry *	buffer (double distance, int segments, QString *errorMsg=nullptr) const override

QgsAbstractGeometry *	buffer (double distance, int segments, int endCapStyle, int joinStyle, double miterLimit, QString *errorMsg=nullptr) const override

QgsPoint *	centroid (QString *errorMsg=nullptr) const override
	Calculates the centroid of this. More...

std::unique_ptr< QgsAbstractGeometry >	clip (const QgsRectangle &rectangle, QString *errorMsg=nullptr) const
	Performs a fast, non-robust intersection between the geometry and a rectangle. More...

QgsGeometry	closestPoint (const QgsGeometry &other, QString *errorMsg=nullptr) const
	Returns the closest point on the geometry to the other geometry. More...

QgsAbstractGeometry *	combine (const QgsAbstractGeometry geom, QString errorMsg=nullptr) const override
	Calculate the combination of this and geom. More...

QgsAbstractGeometry *	combine (const QVector< QgsAbstractGeometry > &geomList, QString errorMsg) const override
	Calculate the combination of this and geometries. More...

QgsAbstractGeometry *	combine (const QVector< QgsGeometry > &, QString *errorMsg=nullptr) const override
	Calculate the combination of this and geometries. More...

bool	contains (const QgsAbstractGeometry geom, QString errorMsg=nullptr) const override
	Checks if geom contains this. More...

QgsAbstractGeometry *	convexHull (QString *errorMsg=nullptr) const override
	Calculate the convex hull of this. More...

bool	crosses (const QgsAbstractGeometry geom, QString errorMsg=nullptr) const override
	Checks if geom crosses this. More...

QgsGeometry	delaunayTriangulation (double tolerance=0.0, bool edgesOnly=false, QString *errorMsg=nullptr) const
	Returns the Delaunay triangulation for the vertices of the geometry. More...

QgsAbstractGeometry *	difference (const QgsAbstractGeometry geom, QString errorMsg=nullptr) const override
	Calculate the difference of this and geom. More...

bool	disjoint (const QgsAbstractGeometry geom, QString errorMsg=nullptr) const override
	Checks if geom is disjoint from this. More...

double	distance (const QgsAbstractGeometry geom, QString errorMsg=nullptr) const override
	Calculates the distance between this and geom. More...

QgsAbstractGeometry *	envelope (QString *errorMsg=nullptr) const override

void	geometryChanged () override
	Should be called whenever the geometry associated with the engine has been modified and the engine must be updated to suit. More...

double	hausdorffDistance (const QgsAbstractGeometry geom, QString errorMsg=nullptr) const
	Returns the Hausdorff distance between this geometry and geom. More...

double	hausdorffDistanceDensify (const QgsAbstractGeometry geom, double densifyFraction, QString errorMsg=nullptr) const
	Returns the Hausdorff distance between this geometry and geom. More...

QgsAbstractGeometry *	interpolate (double distance, QString *errorMsg=nullptr) const override

QgsAbstractGeometry *	intersection (const QgsAbstractGeometry geom, QString errorMsg=nullptr) const override
	Calculate the intersection of this and geom. More...

bool	intersects (const QgsAbstractGeometry geom, QString errorMsg=nullptr) const override
	Checks if geom intersects this. More...

bool	isEmpty (QString *errorMsg=nullptr) const override

bool	isEqual (const QgsAbstractGeometry geom, QString errorMsg=nullptr) const override
	Checks if this is equal to geom. More...

bool	isSimple (QString *errorMsg=nullptr) const override
	Determines whether the geometry is simple (according to OGC definition). More...

bool	isValid (QString *errorMsg=nullptr) const override

double	length (QString *errorMsg=nullptr) const override

double	lineLocatePoint (const QgsPoint &point, QString *errorMsg=nullptr) const
	Returns a distance representing the location along this linestring of the closest point on this linestring geometry to the specified point. More...

QgsGeometry	mergeLines (QString *errorMsg=nullptr) const
	Merges any connected lines in a LineString/MultiLineString geometry and converts them to single line strings. More...

QgsAbstractGeometry *	offsetCurve (double distance, int segments, int joinStyle, double miterLimit, QString *errorMsg=nullptr) const override

bool	overlaps (const QgsAbstractGeometry geom, QString errorMsg=nullptr) const override
	Checks if geom overlaps this. More...

QgsPoint *	pointOnSurface (QString *errorMsg=nullptr) const override
	Calculate a point that is guaranteed to be on the surface of this. More...

void	prepareGeometry () override
	Prepares the geometry, so that subsequent calls to spatial relation methods are much faster. More...

QString	relate (const QgsAbstractGeometry geom, QString errorMsg=nullptr) const override
	Returns the Dimensional Extended 9 Intersection Model (DE-9IM) representation of the relationship between the geometries. More...

bool	relatePattern (const QgsAbstractGeometry geom, const QString &pattern, QString errorMsg=nullptr) const override
	Tests whether two geometries are related by a specified Dimensional Extended 9 Intersection Model (DE-9IM) pattern. More...

std::unique_ptr< QgsAbstractGeometry >	reshapeGeometry (const QgsLineString &reshapeWithLine, EngineOperationResult errorCode, QString errorMsg=nullptr) const
	Reshapes the geometry using a line. More...

QgsGeometry	shortestLine (const QgsGeometry &other, QString *errorMsg=nullptr) const
	Returns the shortest line joining this geometry to the other geometry. More...

QgsAbstractGeometry *	simplify (double tolerance, QString *errorMsg=nullptr) const override

std::unique_ptr< QgsAbstractGeometry >	singleSidedBuffer (double distance, int segments, int side, int joinStyle, double miterLimit, QString *errorMsg=nullptr) const
	Returns a single sided buffer for a geometry. More...

EngineOperationResult	splitGeometry (const QgsLineString &splitLine, QVector< QgsGeometry > &newGeometries, bool topological, QgsPointSequence &topologyTestPoints, QString *errorMsg=nullptr) const override
	Splits this geometry according to a given line. More...

std::unique_ptr< QgsAbstractGeometry >	subdivide (int maxNodes, QString *errorMsg=nullptr) const
	Subdivides the geometry. More...

QgsAbstractGeometry *	symDifference (const QgsAbstractGeometry geom, QString errorMsg=nullptr) const override
	Calculate the symmetric difference of this and geom. More...

bool	touches (const QgsAbstractGeometry geom, QString errorMsg=nullptr) const override
	Checks if geom touches this. More...

QgsGeometry	voronoiDiagram (const QgsAbstractGeometry extent=nullptr, double tolerance=0.0, bool edgesOnly=false, QString errorMsg=nullptr) const
	Creates a Voronoi diagram for the nodes contained within the geometry. More...

bool	within (const QgsAbstractGeometry geom, QString errorMsg=nullptr) const override
	Checks if geom is within this. More...

Public Member Functions inherited from QgsGeometryEngine
virtual	~QgsGeometryEngine ()=default

Static Public Member Functions
static QgsGeometry::OperationResult	addPart (QgsGeometry &geometry, GEOSGeometry *newPart)
	Adds a new island polygon to a multipolygon feature. More...

static geos::unique_ptr	asGeos (const QgsGeometry &geometry, double precision=0)
	Returns a geos geometry - caller takes ownership of the object (should be deleted with GEOSGeom_destroy_r) More...

static geos::unique_ptr	asGeos (const QgsAbstractGeometry *geometry, double precision=0)
	Returns a geos geometry - caller takes ownership of the object (should be deleted with GEOSGeom_destroy_r) More...

static QgsPoint	coordSeqPoint (const GEOSCoordSequence *cs, int i, bool hasZ, bool hasM)

static std::unique_ptr< QgsAbstractGeometry >	fromGeos (const GEOSGeometry *geos)
	Create a geometry from a GEOSGeometry. More...

static std::unique_ptr< QgsPolygon >	fromGeosPolygon (const GEOSGeometry *geos)

static QgsGeometry	geometryFromGeos (GEOSGeometry *geos)
	Creates a new QgsGeometry object, feeding in a geometry in GEOS format. More...

static QgsGeometry	geometryFromGeos (geos::unique_ptr geos)
	Creates a new QgsGeometry object, feeding in a geometry in GEOS format. More...

static GEOSContextHandle_t	getGEOSHandler ()

static QgsGeometry	polygonize (const QVector< const QgsAbstractGeometry > &geometries, QString errorMsg=nullptr)
	Creates a GeometryCollection geometry containing possible polygons formed from the constituent linework of a set of geometries. More...

Additional Inherited Members
Public Types inherited from QgsGeometryEngine
enum	EngineOperationResult { Success = 0, NothingHappened = 1000, MethodNotImplemented, EngineError, NodedGeometryError, InvalidBaseGeometry, InvalidInput, SplitCannotSplitPoint }
	Success or failure of a geometry operation. More...

Protected Member Functions inherited from QgsGeometryEngine
	QgsGeometryEngine (const QgsAbstractGeometry *geometry)

Protected Attributes inherited from QgsGeometryEngine
const QgsAbstractGeometry *	mGeometry = nullptr

Detailed Description

Does vector analysis using the geos library and handles import, export, exception handling*.

Note: not available in Python bindings

Definition at line 103 of file qgsgeos.h.

Constructor & Destructor Documentation

◆ QgsGeos()

QgsGeos::QgsGeos	(	const QgsAbstractGeometry *	geometry,
		double	precision = `0`
	)

GEOS geometry engine constructor.

Parameters

geometry	The geometry
precision	The precision of the grid to which to snap the geometry vertices. If 0, no snapping is performed.

Definition at line 145 of file qgsgeos.cpp.

Member Function Documentation

◆ addPart()

QgsGeometry::OperationResult QgsGeos::addPart	(	QgsGeometry &	geometry,
		GEOSGeometry *	newPart
	)

static

Adds a new island polygon to a multipolygon feature.

Parameters

geometry	geometry to add part to
newPart	part to add. Ownership is NOT transferred.

Returns: OperationResult a result code: success or reason of failure

Definition at line 176 of file qgsgeos.cpp.

◆ area()

double QgsGeos::area ( QString * errorMsg = nullptr ) const

overridevirtual

Implements QgsGeometryEngine.

Definition at line 586 of file qgsgeos.cpp.

◆ asGeos() [1/2]

geos::unique_ptr QgsGeos::asGeos	(	const QgsGeometry &	geometry,
		double	precision = `0`
	)

static

Returns a geos geometry - caller takes ownership of the object (should be deleted with GEOSGeom_destroy_r)

Parameters

geometry	geometry to convert to GEOS representation
precision	The precision of the grid to which to snap the geometry vertices. If 0, no snapping is performed.

Definition at line 166 of file qgsgeos.cpp.

◆ asGeos() [2/2]

geos::unique_ptr QgsGeos::asGeos	(	const QgsAbstractGeometry *	geometry,
		double	precision = `0`
	)

static

Returns a geos geometry - caller takes ownership of the object (should be deleted with GEOSGeom_destroy_r)

Parameters

geometry	geometry to convert to GEOS representation
precision	The precision of the grid to which to snap the geometry vertices. If 0, no snapping is performed.

Definition at line 1288 of file qgsgeos.cpp.

◆ buffer() [1/2]

QgsAbstractGeometry * QgsGeos::buffer	(	double	distance,
		int	segments,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Implements QgsGeometryEngine.

Definition at line 1512 of file qgsgeos.cpp.

◆ buffer() [2/2]

QgsAbstractGeometry * QgsGeos::buffer	(	double	distance,
		int	segments,
		int	endCapStyle,
		int	joinStyle,
		double	miterLimit,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Implements QgsGeometryEngine.

Definition at line 1528 of file qgsgeos.cpp.

◆ centroid()

QgsPoint * QgsGeos::centroid ( QString * errorMsg = nullptr ) const

overridevirtual

Calculates the centroid of this.

May return a nullptr.

Since: QGIS 3.0 the centroid is returned

Implements QgsGeometryEngine.

Definition at line 1574 of file qgsgeos.cpp.

◆ clip()

std::unique_ptr< QgsAbstractGeometry > QgsGeos::clip	(	const QgsRectangle &	rectangle,
		QString *	errorMsg = `nullptr`
	)		const

Performs a fast, non-robust intersection between the geometry and a rectangle.

The returned geometry may be invalid.

Definition at line 227 of file qgsgeos.cpp.

◆ closestPoint()

QgsGeometry QgsGeos::closestPoint	(	const QgsGeometry &	other,
		QString *	errorMsg = `nullptr`
	)		const

Returns the closest point on the geometry to the other geometry.

See also: shortestLine()

Since: QGIS 2.14

Definition at line 2112 of file qgsgeos.cpp.

◆ combine() [1/3]

QgsAbstractGeometry * QgsGeos::combine	(	const QgsAbstractGeometry *	geom,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Calculate the combination of this and geom.

Since: QGIS 3.0 geom is a pointer

Implements QgsGeometryEngine.

Definition at line 361 of file qgsgeos.cpp.

◆ combine() [2/3]

QgsAbstractGeometry * QgsGeos::combine	(	const QVector< QgsAbstractGeometry *> &	geomList,
		QString *	errorMsg
	)		const

overridevirtual

Calculate the combination of this and geometries.

Since: QGIS 3.0 geom is a pointer

Implements QgsGeometryEngine.

Definition at line 366 of file qgsgeos.cpp.

◆ combine() [3/3]

QgsAbstractGeometry * QgsGeos::combine	(	const QVector< QgsGeometry > &	geometries,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Calculate the combination of this and geometries.

Since: QGIS 3.0 geom is a pointer

Implements QgsGeometryEngine.

Definition at line 390 of file qgsgeos.cpp.

◆ contains()

bool QgsGeos::contains	(	const QgsAbstractGeometry *	geom,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Checks if geom contains this.

Since: QGIS 3.0 geom is a pointer

Implements QgsGeometryEngine.

Definition at line 513 of file qgsgeos.cpp.

◆ convexHull()

QgsAbstractGeometry * QgsGeos::convexHull ( QString * errorMsg = nullptr ) const

overridevirtual

Calculate the convex hull of this.

Implements QgsGeometryEngine.

Definition at line 1643 of file qgsgeos.cpp.

◆ coordSeqPoint()

QgsPoint QgsGeos::coordSeqPoint	(	const GEOSCoordSequence *	cs,
		int	i,
		bool	hasZ,
		bool	hasM
	)

static

Definition at line 1251 of file qgsgeos.cpp.

◆ crosses()

bool QgsGeos::crosses	(	const QgsAbstractGeometry *	geom,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Checks if geom crosses this.

Since: QGIS 3.0 geom is a pointer

Implements QgsGeometryEngine.

Definition at line 498 of file qgsgeos.cpp.

◆ delaunayTriangulation()

QgsGeometry QgsGeos::delaunayTriangulation	(	double	tolerance = `0.0`,
		bool	edgesOnly = `false`,
		QString *	errorMsg = `nullptr`
	)		const

Returns the Delaunay triangulation for the vertices of the geometry.

The tolerance parameter specifies an optional snapping tolerance which can be used to improve the robustness of the triangulation. If edgesOnly is true than line string boundary geometries will be returned instead of polygons. An empty geometry will be returned if the diagram could not be calculated.

Since: QGIS 3.0

Definition at line 2288 of file qgsgeos.cpp.

◆ difference()

QgsAbstractGeometry * QgsGeos::difference	(	const QgsAbstractGeometry *	geom,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Calculate the difference of this and geom.

Since: QGIS 3.0 geom is a pointer

Implements QgsGeometryEngine.

Definition at line 222 of file qgsgeos.cpp.

◆ disjoint()

bool QgsGeos::disjoint	(	const QgsAbstractGeometry *	geom,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Checks if geom is disjoint from this.

Since: QGIS 3.0 geom is a pointer

Implements QgsGeometryEngine.

Definition at line 518 of file qgsgeos.cpp.

◆ distance()

double QgsGeos::distance	(	const QgsAbstractGeometry *	geom,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Calculates the distance between this and geom.

Since: QGIS 3.0 geom is a pointer

Implements QgsGeometryEngine.

Definition at line 419 of file qgsgeos.cpp.

◆ envelope()

QgsAbstractGeometry * QgsGeos::envelope ( QString * errorMsg = nullptr ) const

overridevirtual

Implements QgsGeometryEngine.

Definition at line 1600 of file qgsgeos.cpp.

◆ fromGeos()

std::unique_ptr< QgsAbstractGeometry > QgsGeos::fromGeos ( const GEOSGeometry * geos )

static

Create a geometry from a GEOSGeometry.

Parameters

geos	GEOSGeometry. Ownership is NOT transferred.

Definition at line 1081 of file qgsgeos.cpp.

◆ fromGeosPolygon()

std::unique_ptr< QgsPolygon > QgsGeos::fromGeosPolygon ( const GEOSGeometry * geos )

static

Definition at line 1169 of file qgsgeos.cpp.

◆ geometryChanged()

void QgsGeos::geometryChanged ( )

overridevirtual

Should be called whenever the geometry associated with the engine has been modified and the engine must be updated to suit.

Implements QgsGeometryEngine.

Definition at line 191 of file qgsgeos.cpp.

◆ geometryFromGeos() [1/2]

QgsGeometry QgsGeos::geometryFromGeos ( GEOSGeometry * geos )

static

Creates a new QgsGeometry object, feeding in a geometry in GEOS format.

This class will take ownership of the buffer.

Definition at line 153 of file qgsgeos.cpp.

◆ geometryFromGeos() [2/2]

QgsGeometry QgsGeos::geometryFromGeos ( geos::unique_ptr geos )

static

Creates a new QgsGeometry object, feeding in a geometry in GEOS format.

Definition at line 160 of file qgsgeos.cpp.

◆ getGEOSHandler()

GEOSContextHandle_t QgsGeos::getGEOSHandler ( )

static

Definition at line 2775 of file qgsgeos.cpp.

◆ hausdorffDistance()

double QgsGeos::hausdorffDistance	(	const QgsAbstractGeometry *	geom,
		QString *	errorMsg = `nullptr`
	)		const

Returns the Hausdorff distance between this geometry and geom.

This is basically a measure of how similar or dissimilar 2 geometries are.

This algorithm is an approximation to the standard Hausdorff distance. This approximation is exact or close enough for a large subset of useful cases. Examples of these are:

computing distance between Linestrings that are roughly parallel to each other, and roughly equal in length. This occurs in matching linear networks.
Testing similarity of geometries.

If the default approximate provided by this method is insufficient, use hausdorffDistanceDensify() instead.

See also: hausdorffDistanceDensify()

Since: QGIS 3.0

Definition at line 442 of file qgsgeos.cpp.

◆ hausdorffDistanceDensify()

double QgsGeos::hausdorffDistanceDensify	(	const QgsAbstractGeometry *	geom,
		double	densifyFraction,
		QString *	errorMsg = `nullptr`
	)		const

Returns the Hausdorff distance between this geometry and geom.

This is basically a measure of how similar or dissimilar 2 geometries are.

This function accepts a densifyFraction argument. The function performs a segment densification before computing the discrete Hausdorff distance. The densifyFraction parameter sets the fraction by which to densify each segment. Each segment will be split into a number of equal-length subsegments, whose fraction of the total length is closest to the given fraction.

This method can be used when the default approximation provided by hausdorffDistance() is not sufficient. Decreasing the densifyFraction parameter will make the distance returned approach the true Hausdorff distance for the geometries.

See also: hausdorffDistance()

Since: QGIS 3.0

Definition at line 465 of file qgsgeos.cpp.

◆ interpolate()

QgsAbstractGeometry * QgsGeos::interpolate	(	double	distance,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Implements QgsGeometryEngine.

Definition at line 1559 of file qgsgeos.cpp.

◆ intersection()

QgsAbstractGeometry * QgsGeos::intersection	(	const QgsAbstractGeometry *	geom,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Calculate the intersection of this and geom.

Since: QGIS 3.0 geom is a pointer

Implements QgsGeometryEngine.

Definition at line 217 of file qgsgeos.cpp.

◆ intersects()

bool QgsGeos::intersects	(	const QgsAbstractGeometry *	geom,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Checks if geom intersects this.

Since: QGIS 3.0 geom is a pointer

Implements QgsGeometryEngine.

Definition at line 488 of file qgsgeos.cpp.

◆ isEmpty()

bool QgsGeos::isEmpty ( QString * errorMsg = nullptr ) const

overridevirtual

Implements QgsGeometryEngine.

Definition at line 1693 of file qgsgeos.cpp.

◆ isEqual()

bool QgsGeos::isEqual	(	const QgsAbstractGeometry *	geom,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Checks if this is equal to geom.

If both are Null geometries, false is returned.

Since: QGIS 3.0 geom is a pointer

Implements QgsGeometryEngine.

Definition at line 1673 of file qgsgeos.cpp.

◆ isSimple()

bool QgsGeos::isSimple ( QString * errorMsg = nullptr ) const

overridevirtual

Determines whether the geometry is simple (according to OGC definition).

Since: QGIS 3.0

Implements QgsGeometryEngine.

Definition at line 1707 of file qgsgeos.cpp.

◆ isValid()

bool QgsGeos::isValid ( QString * errorMsg = nullptr ) const

overridevirtual

Implements QgsGeometryEngine.

Definition at line 1659 of file qgsgeos.cpp.

◆ length()

double QgsGeos::length ( QString * errorMsg = nullptr ) const

overridevirtual

Implements QgsGeometryEngine.

Definition at line 603 of file qgsgeos.cpp.

◆ lineLocatePoint()

double QgsGeos::lineLocatePoint	(	const QgsPoint &	point,
		QString *	errorMsg = `nullptr`
	)		const

Returns a distance representing the location along this linestring of the closest point on this linestring geometry to the specified point.

Ie, the returned value indicates how far along this linestring you need to traverse to get to the closest location where this linestring comes to the specified point.

Parameters

point	point to seek proximity to
errorMsg	error messages emitted, if any

Returns: distance along line, or -1 on error

Note: only valid for linestring geometries

Definition at line 2187 of file qgsgeos.cpp.

◆ mergeLines()

QgsGeometry QgsGeos::mergeLines ( QString * errorMsg = nullptr ) const

Merges any connected lines in a LineString/MultiLineString geometry and converts them to single line strings.

Parameters

errorMsg if specified, will be set to any reported GEOS errors

Returns: a LineString or MultiLineString geometry, with any connected lines joined. An empty geometry will be returned if the input geometry was not a LineString/MultiLineString geometry.

Since: QGIS 3.0

Definition at line 2093 of file qgsgeos.cpp.

◆ offsetCurve()

QgsAbstractGeometry * QgsGeos::offsetCurve	(	double	distance,
		int	segments,
		int	joinStyle,
		double	miterLimit,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Implements QgsGeometryEngine.

Definition at line 1936 of file qgsgeos.cpp.

◆ overlaps()

bool QgsGeos::overlaps	(	const QgsAbstractGeometry *	geom,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Checks if geom overlaps this.

Since: QGIS 3.0 geom is a pointer

Implements QgsGeometryEngine.

Definition at line 508 of file qgsgeos.cpp.

◆ pointOnSurface()

QgsPoint * QgsGeos::pointOnSurface ( QString * errorMsg = nullptr ) const

overridevirtual

Calculate a point that is guaranteed to be on the surface of this.

May return a nullptr.

Since: QGIS 3.0 the centroid is returned

Implements QgsGeometryEngine.

Definition at line 1615 of file qgsgeos.cpp.

◆ polygonize()

QgsGeometry QgsGeos::polygonize	(	const QVector< const QgsAbstractGeometry *> &	geometries,
		QString *	errorMsg = `nullptr`
	)

static

Creates a GeometryCollection geometry containing possible polygons formed from the constituent linework of a set of geometries.

The input geometries must be fully noded (i.e. nodes exist at every common intersection of the geometries). The easiest way to ensure this is to first unary union these geometries by calling combine() on the set of input geometries and then pass the result to polygonize(). An empty geometry will be returned in the case of errors.

Since: QGIS 3.0

Definition at line 2217 of file qgsgeos.cpp.

◆ prepareGeometry()

void QgsGeos::prepareGeometry ( )

overridevirtual

Prepares the geometry, so that subsequent calls to spatial relation methods are much faster.

This should be called for any geometry which is used for multiple relation tests against other geometries.

See also: geometryChanged()

Implements QgsGeometryEngine.

Definition at line 198 of file qgsgeos.cpp.

◆ relate()

QString QgsGeos::relate	(	const QgsAbstractGeometry *	geom,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Returns the Dimensional Extended 9 Intersection Model (DE-9IM) representation of the relationship between the geometries.

Parameters

geom	geometry to relate to
errorMsg	destination storage for any error message

Returns: DE-9IM string for relationship, or an empty string if an error occurred

Since: QGIS 2.12

Implements QgsGeometryEngine.

Definition at line 523 of file qgsgeos.cpp.

◆ relatePattern()

bool QgsGeos::relatePattern	(	const QgsAbstractGeometry *	geom,
		const QString &	pattern,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Tests whether two geometries are related by a specified Dimensional Extended 9 Intersection Model (DE-9IM) pattern.

Parameters

geom	geometry to relate to
pattern	DE-9IM pattern for match
errorMsg	destination storage for any error message

Returns: true if geometry relationship matches with pattern

Since: QGIS 2.14

Implements QgsGeometryEngine.

Definition at line 557 of file qgsgeos.cpp.

◆ reshapeGeometry()

std::unique_ptr< QgsAbstractGeometry > QgsGeos::reshapeGeometry	(	const QgsLineString &	reshapeWithLine,
		EngineOperationResult *	errorCode,
		QString *	errorMsg = `nullptr`
	)		const

Reshapes the geometry using a line.

Parameters

reshapeWithLine	the line used to reshape lines or polygons
errorCode	if specified, provides result of operation (success or reason of failure)
errorMsg	if specified, provides more details about failure

Returns: the reshaped geometry

Definition at line 1977 of file qgsgeos.cpp.

◆ shortestLine()

QgsGeometry QgsGeos::shortestLine	(	const QgsGeometry &	other,
		QString *	errorMsg = `nullptr`
	)		const

Returns the shortest line joining this geometry to the other geometry.

See also: closestPoint()

Since: QGIS 2.14

Definition at line 2146 of file qgsgeos.cpp.

◆ simplify()

QgsAbstractGeometry * QgsGeos::simplify	(	double	tolerance,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Implements QgsGeometryEngine.

Definition at line 1544 of file qgsgeos.cpp.

◆ singleSidedBuffer()

std::unique_ptr< QgsAbstractGeometry > QgsGeos::singleSidedBuffer	(	double	distance,
		int	segments,
		int	side,
		int	joinStyle,
		double	miterLimit,
		QString *	errorMsg = `nullptr`
	)		const

Returns a single sided buffer for a geometry.

The buffer is only applied to one side of the geometry.

Parameters

distance	buffer distance
segments	for round joins, number of segments to approximate quarter-circle
side	side of geometry to buffer (0 = left, 1 = right)
joinStyle	join style for corners ( Round (1) / Miter (2) / Bevel (3) )
miterLimit	limit on the miter ratio used for very sharp corners
errorMsg	error messages emitted, if any

Returns: buffered geometry, or an nullptr if buffer could not be calculated

Since: QGIS 3.0

Definition at line 1951 of file qgsgeos.cpp.

◆ splitGeometry()

QgsGeometryEngine::EngineOperationResult QgsGeos::splitGeometry	(	const QgsLineString &	splitLine,
		QVector< QgsGeometry > &	newGeometries,
		bool	topological,
		QgsPointSequence &	topologyTestPoints,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Splits this geometry according to a given line.

Parameters

	splitLine	the line that splits the geometry
[out]	newGeometries	list of new geometries that have been created with the split
	topological	true if topological editing is enabled
[out]	topologyTestPoints	points that need to be tested for topological completeness in the dataset
[out]	errorMsg	error messages emitted, if any

Returns: 0 in case of success, 1 if geometry has not been split, error else

Reimplemented from QgsGeometryEngine.

Definition at line 619 of file qgsgeos.cpp.

◆ subdivide()

std::unique_ptr< QgsAbstractGeometry > QgsGeos::subdivide	(	int	maxNodes,
		QString *	errorMsg = `nullptr`
	)		const

Subdivides the geometry.

The returned geometry will be a collection containing subdivided parts from the original geometry, where no part has more then the specified maximum number of nodes (maxNodes).

This is useful for dividing a complex geometry into less complex parts, which are better able to be spatially indexed and faster to perform further operations such as intersects on. The returned geometry parts may not be valid and may contain self-intersections.

The minimum allowed value for maxNodes is 8.

Curved geometries are not supported.

Since: QGIS 3.0

Definition at line 341 of file qgsgeos.cpp.

◆ symDifference()

QgsAbstractGeometry * QgsGeos::symDifference	(	const QgsAbstractGeometry *	geom,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Calculate the symmetric difference of this and geom.

Since: QGIS 3.0 geom is a pointer

Implements QgsGeometryEngine.

Definition at line 414 of file qgsgeos.cpp.

◆ touches()

bool QgsGeos::touches	(	const QgsAbstractGeometry *	geom,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Checks if geom touches this.

Since: QGIS 3.0 geom is a pointer

Implements QgsGeometryEngine.

Definition at line 493 of file qgsgeos.cpp.

◆ voronoiDiagram()

QgsGeometry QgsGeos::voronoiDiagram	(	const QgsAbstractGeometry *	extent = `nullptr`,
		double	tolerance = `0.0`,
		bool	edgesOnly = `false`,
		QString *	errorMsg = `nullptr`
	)		const

Creates a Voronoi diagram for the nodes contained within the geometry.

Returns the Voronoi polygons for the nodes contained within the geometry. If extent is specified then it will be used as a clipping envelope for the diagram. If no extent is set then the clipping envelope will be automatically calculated. In either case the diagram will be clipped to the larger of the provided envelope OR the envelope surrounding all input nodes. The tolerance parameter specifies an optional snapping tolerance which can be used to improve the robustness of the diagram calculation. If edgesOnly is true than line string boundary geometries will be returned instead of polygons. An empty geometry will be returned if the diagram could not be calculated.

Since: QGIS 3.0

Definition at line 2256 of file qgsgeos.cpp.

◆ within()

bool QgsGeos::within	(	const QgsAbstractGeometry *	geom,
		QString *	errorMsg = `nullptr`
	)		const

overridevirtual

Checks if geom is within this.

Since: QGIS 3.0 geom is a pointer

Implements QgsGeometryEngine.

Definition at line 503 of file qgsgeos.cpp.

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

/tmp/buildd/qgis-3.2.0+99unstable/src/core/geometry/qgsgeos.h
/tmp/buildd/qgis-3.2.0+99unstable/src/core/geometry/qgsgeos.cpp

Public Member Functions

Static Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ QgsGeos()

Member Function Documentation

◆ addPart()

◆ area()

◆ asGeos() [1/2]

◆ asGeos() [2/2]

◆ buffer() [1/2]

◆ buffer() [2/2]

◆ centroid()

◆ clip()

◆ closestPoint()

◆ combine() [1/3]

◆ combine() [2/3]

◆ combine() [3/3]

◆ contains()

◆ convexHull()

◆ coordSeqPoint()

◆ crosses()

◆ delaunayTriangulation()

◆ difference()

◆ disjoint()

◆ distance()

◆ envelope()

◆ fromGeos()

◆ fromGeosPolygon()

◆ geometryChanged()

◆ geometryFromGeos() [1/2]

◆ geometryFromGeos() [2/2]

◆ getGEOSHandler()

◆ hausdorffDistance()

◆ hausdorffDistanceDensify()

◆ interpolate()

◆ intersection()

◆ intersects()

◆ isEmpty()

◆ isEqual()

◆ isSimple()

◆ isValid()

◆ length()

◆ lineLocatePoint()

◆ mergeLines()

◆ offsetCurve()

◆ overlaps()

◆ pointOnSurface()

◆ polygonize()

◆ prepareGeometry()

◆ relate()

◆ relatePattern()

◆ reshapeGeometry()

◆ shortestLine()

◆ simplify()

◆ singleSidedBuffer()

◆ splitGeometry()

◆ subdivide()

◆ symDifference()

◆ touches()

◆ voronoiDiagram()

◆ within()