Contains various geometry utility functions. More...

#include <qgsgeometryutils.h>

Classes
struct	SelfIntersection

Public Types
enum	componentType { VERTEX, RING, PART }

Static Public Member Functions
static void	adjacentVertices (const QgsAbstractGeometryV2 &geom, QgsVertexId atVertex, QgsVertexId &beforeVertex, QgsVertexId &afterVertex)
	Returns vertices adjacent to a specified vertex within a geometry. More...

static bool	angleOnCircle (double angle, double angle1, double angle2, double angle3)
	Returns true if an angle is between angle1 and angle3 on a circle described by angle1, angle2 and angle3. More...

static double	averageAngle (double x1, double y1, double x2, double y2, double x3, double y3)
	Angle between two linear segments. More...

static double	averageAngle (double a1, double a2)
	Averages two angles, correctly handling negative angles and ensuring the result is between 0 and 2 pi. More...

static double	ccwAngle (double dy, double dx)
	Returns the counter clockwise angle between a line with components dx, dy and the line with dx > 0 and dy = 0. More...

static bool	circleAngleBetween (double angle, double angle1, double angle2, bool clockwise)
	Returns true if, in a circle, angle is between angle1 and angle2. More...

static void	circleCenterRadius (const QgsPointV2 &pt1, const QgsPointV2 &pt2, const QgsPointV2 &pt3, double &radius, double &centerX, double &centerY)
	Returns radius and center of the circle through pt1, pt2, pt3. More...

static bool	circleClockwise (double angle1, double angle2, double angle3)
	Returns true if circle is ordered clockwise. More...

static double	circleLength (double x1, double y1, double x2, double y2, double x3, double y3)
	Length of a circular string segment defined by pt1, pt2, pt3. More...

static double	circleTangentDirection (const QgsPointV2 &tangentPoint, const QgsPointV2 &cp1, const QgsPointV2 &cp2, const QgsPointV2 &cp3)
	Calculates the direction angle of a circle tangent (clockwise from north in radians) More...

template<class T >
static double	closestSegmentFromComponents (T &container, componentType ctype, const QgsPointV2 &pt, QgsPointV2 &segmentPt, QgsVertexId &vertexAfter, bool *leftOf, double epsilon)

static QgsPointV2	closestVertex (const QgsAbstractGeometryV2 &geom, const QgsPointV2 &pt, QgsVertexId &id)
	Returns the closest vertex to a geometry for a specified point. More...

static double	distanceToVertex (const QgsAbstractGeometryV2 &geom, const QgsVertexId &id)
	Returns the distance along a geometry from its first vertex to the specified vertex. More...

static QList< QgsLineStringV2 * >	extractLineStrings (const QgsAbstractGeometryV2 *geom)
	Returns list of linestrings extracted from the passed geometry. More...

static QList< SelfIntersection >	getSelfIntersections (const QgsAbstractGeometryV2 *geom, int part, int ring, double tolerance)
	Find self intersections in a polyline. More...

static double	leftOfLine (double x, double y, double x1, double y1, double x2, double y2)
	Returns < 0 if point(x/y) is left of the line x1,y1 -> x2,y2. More...

static double	lineAngle (double x1, double y1, double x2, double y2)
	Calculates the direction of line joining two points in radians, clockwise from the north direction. More...

static bool	lineIntersection (const QgsPointV2 &p1, QgsVector v, const QgsPointV2 &q1, QgsVector w, QgsPointV2 &inter)
	Compute the intersection between two lines. More...

static double	linePerpendicularAngle (double x1, double y1, double x2, double y2)
	Calculates the perpendicular angle to a line joining two points. More...

static double	normalizedAngle (double angle)
	Ensures that an angle is in the range 0 <= angle < 2 pi. More...

static QgsPointV2	pointOnLineWithDistance (const QgsPointV2 &startPoint, const QgsPointV2 &directionPoint, double distance)
	Returns a point a specified distance toward a second point. More...

static QgsPointSequenceV2	pointsFromWKT (const QString &wktCoordinateList, bool is3D, bool isMeasure)
	Returns a list of points contained in a WKT string. More...

static QDomElement	pointsToGML2 (const QgsPointSequenceV2 &points, QDomDocument &doc, int precision, const QString &ns)
	Returns a gml::coordinates DOM element. More...

static QDomElement	pointsToGML3 (const QgsPointSequenceV2 &points, QDomDocument &doc, int precision, const QString &ns, bool is3D)
	Returns a gml::posList DOM element. More...

static QString	pointsToJSON (const QgsPointSequenceV2 &points, int precision)
	Returns a geoJSON coordinates string. More...

static void	pointsToWKB (QgsWkbPtr &wkb, const QgsPointSequenceV2 &points, bool is3D, bool isMeasure)
	Returns a LinearRing { uint32 numPoints; Point points[numPoints]; }. More...

static QString	pointsToWKT (const QgsPointSequenceV2 &points, int precision, bool is3D, bool isMeasure)
	Returns a WKT coordinate list. More...

static QgsPointV2	projPointOnSegment (const QgsPointV2 &p, const QgsPointV2 &s1, const QgsPointV2 &s2)
	Project the point on a segment. More...

static bool	segmentIntersection (const QgsPointV2 &p1, const QgsPointV2 &p2, const QgsPointV2 &q1, const QgsPointV2 &q2, QgsPointV2 &inter, double tolerance)
	Compute the intersection between two segments. More...

static bool	segmentMidPoint (const QgsPointV2 &p1, const QgsPointV2 &p2, QgsPointV2 &result, double radius, const QgsPointV2 &mousePos)
	Calculates midpoint on circle passing through p1 and p2, closest to given coordinate. More...

static double	sqrDistance2D (const QgsPointV2 &pt1, const QgsPointV2 &pt2)
	Returns the squared 2D distance between two points. More...

static double	sqrDistToLine (double ptX, double ptY, double x1, double y1, double x2, double y2, double &minDistX, double &minDistY, double epsilon)
	Returns the squared distance between a point and a line. More...

static double	sweepAngle (double centerX, double centerY, double x1, double y1, double x2, double y2, double x3, double y3)
	Calculates angle of a circular string part defined by pt1, pt2, pt3. More...

static bool	verticesAtDistance (const QgsAbstractGeometryV2 &geometry, double distance, QgsVertexId &previousVertex, QgsVertexId &nextVertex)
	Retrieves the vertices which are before and after the interpolated point at a specified distance along a linestring (or polygon boundary). More...

static QStringList	wktGetChildBlocks (const QString &wkt, const QString &defaultType="")
	Parses a WKT string and returns of list of blocks contained in the WKT. More...

static QPair< QgsWKBTypes::Type, QString >	wktReadBlock (const QString &wkt)
	Parses a WKT block of the format "TYPE( contents )" and returns a pair of geometry type to contents ("Pair(wkbType, "contents")") More...

Detailed Description

Contains various geometry utility functions.

Note: added in QGIS 2.10; this API is not considered stable and may change for 2.12; not available in Python bindings

Definition at line 31 of file qgsgeometryutils.h.

Member Enumeration Documentation

◆ componentType

enum QgsGeometryUtils::componentType

Enumerator
VERTEX
RING
PART

Definition at line 233 of file qgsgeometryutils.h.

Member Function Documentation

◆ adjacentVertices()

void QgsGeometryUtils::adjacentVertices	(	const QgsAbstractGeometryV2 &	geom,
		QgsVertexId	atVertex,
		QgsVertexId &	beforeVertex,
		QgsVertexId &	afterVertex
	)

static

Returns vertices adjacent to a specified vertex within a geometry.

Definition at line 168 of file qgsgeometryutils.cpp.

◆ angleOnCircle()

bool QgsGeometryUtils::angleOnCircle	(	double	angle,
		double	angle1,
		double	angle2,
		double	angle3
	)

static

Returns true if an angle is between angle1 and angle3 on a circle described by angle1, angle2 and angle3.

Definition at line 499 of file qgsgeometryutils.cpp.

◆ averageAngle() [1/2]

double QgsGeometryUtils::averageAngle	(	double	x1,
		double	y1,
		double	x2,
		double	y2,
		double	x3,
		double	y3
	)

static

Angle between two linear segments.

Definition at line 844 of file qgsgeometryutils.cpp.

◆ averageAngle() [2/2]

double QgsGeometryUtils::averageAngle	(	double	a1,
		double	a2
	)

static

Averages two angles, correctly handling negative angles and ensuring the result is between 0 and 2 pi.

Parameters

a1	first angle (in radians)
a2	second angle (in radians)

Returns: average angle (in radians)

Definition at line 852 of file qgsgeometryutils.cpp.

◆ ccwAngle()

double QgsGeometryUtils::ccwAngle	(	double	dy,
		double	dx
	)

static

Returns the counter clockwise angle between a line with components dx, dy and the line with dx > 0 and dy = 0.

Definition at line 395 of file qgsgeometryutils.cpp.

◆ circleAngleBetween()

bool QgsGeometryUtils::circleAngleBetween	(	double	angle,
		double	angle1,
		double	angle2,
		bool	clockwise
	)

static

Returns true if, in a circle, angle is between angle1 and angle2.

Definition at line 473 of file qgsgeometryutils.cpp.

◆ circleCenterRadius()

void QgsGeometryUtils::circleCenterRadius	(	const QgsPointV2 &	pt1,
		const QgsPointV2 &	pt2,
		const QgsPointV2 &	pt3,
		double &	radius,
		double &	centerX,
		double &	centerY
	)

static

Returns radius and center of the circle through pt1, pt2, pt3.

Definition at line 409 of file qgsgeometryutils.cpp.

◆ circleClockwise()

bool QgsGeometryUtils::circleClockwise	(	double	angle1,
		double	angle2,
		double	angle3
	)

static

Returns true if circle is ordered clockwise.

Definition at line 447 of file qgsgeometryutils.cpp.

◆ circleLength()

double QgsGeometryUtils::circleLength	(	double	x1,
		double	y1,
		double	x2,
		double	y2,
		double	x3,
		double	y3
	)

static

Length of a circular string segment defined by pt1, pt2, pt3.

Definition at line 505 of file qgsgeometryutils.cpp.

◆ circleTangentDirection()

double QgsGeometryUtils::circleTangentDirection	(	const QgsPointV2 &	tangentPoint,
		const QgsPointV2 &	cp1,
		const QgsPointV2 &	cp2,
		const QgsPointV2 &	cp3
	)

static

Calculates the direction angle of a circle tangent (clockwise from north in radians)

Definition at line 590 of file qgsgeometryutils.cpp.

◆ closestSegmentFromComponents()

template<class T >

static double QgsGeometryUtils::closestSegmentFromComponents	(	T &	container,
		componentType	ctype,
		const QgsPointV2 &	pt,
		QgsPointV2 &	segmentPt,
		QgsVertexId &	vertexAfter,
		bool *	leftOf,
		double	epsilon
	)

inlinestatic

Definition at line 240 of file qgsgeometryutils.h.

◆ closestVertex()

QgsPointV2 QgsGeometryUtils::closestVertex	(	const QgsAbstractGeometryV2 &	geom,
		const QgsPointV2 &	pt,
		QgsVertexId &	id
	)

static

Returns the closest vertex to a geometry for a specified point.

On error null point will be returned and "id" argument will be invalid.

Definition at line 63 of file qgsgeometryutils.cpp.

◆ distanceToVertex()

double QgsGeometryUtils::distanceToVertex	(	const QgsAbstractGeometryV2 &	geom,
		const QgsVertexId &	id
	)

static

Returns the distance along a geometry from its first vertex to the specified vertex.

Parameters

geom	geometry
id	vertex id to find distance to

Returns: distance to vertex (following geometry)

Note: added in QGIS 2.16

Definition at line 94 of file qgsgeometryutils.cpp.

◆ extractLineStrings()

QList< QgsLineStringV2 * > QgsGeometryUtils::extractLineStrings ( const QgsAbstractGeometryV2 * geom )

static

Returns list of linestrings extracted from the passed geometry.

The returned objects have to be deleted by the caller.

Definition at line 27 of file qgsgeometryutils.cpp.

◆ getSelfIntersections()

QList< QgsGeometryUtils::SelfIntersection > QgsGeometryUtils::getSelfIntersections	(	const QgsAbstractGeometryV2 *	geom,
		int	part,
		int	ring,
		double	tolerance
	)

static

Find self intersections in a polyline.

Parameters

geom	The geometry to check
part	The part of the geometry to check
ring	The ring of the geometry part to check
tolerance	The tolerance to use

Returns: The list of self intersections

Note: added in QGIS 2.12

Definition at line 332 of file qgsgeometryutils.cpp.

◆ leftOfLine()

double QgsGeometryUtils::leftOfLine	(	double	x,
		double	y,
		double	x1,
		double	y1,
		double	x2,
		double	y2
	)

static

Returns < 0 if point(x/y) is left of the line x1,y1 -> x2,y2.

Definition at line 371 of file qgsgeometryutils.cpp.

◆ lineAngle()

double QgsGeometryUtils::lineAngle	(	double	x1,
		double	y1,
		double	x2,
		double	y2
	)

static

Calculates the direction of line joining two points in radians, clockwise from the north direction.

Parameters

x1	x-coordinate of line start
y1	y-coordinate of line start
x2	x-coordinate of line end
y2	y-coordinate of line end

Returns: angle in radians. Returned value is undefined if start and end point are the same.

Definition at line 830 of file qgsgeometryutils.cpp.

◆ lineIntersection()

bool QgsGeometryUtils::lineIntersection	(	const QgsPointV2 &	p1,
		QgsVector	v,
		const QgsPointV2 &	q1,
		QgsVector	w,
		QgsPointV2 &	inter
	)

static

Compute the intersection between two lines.

Parameters

p1	Point on the first line
v	Direction vector of the first line
q1	Point on the second line
w	Direction vector of the second line
inter	Output parameter, the intersection point

Returns: Whether the lines intersect

Definition at line 288 of file qgsgeometryutils.cpp.

◆ linePerpendicularAngle()

double QgsGeometryUtils::linePerpendicularAngle	(	double	x1,
		double	y1,
		double	x2,
		double	y2
	)

static

Calculates the perpendicular angle to a line joining two points.

Returned angle is in radians, clockwise from the north direction.

Parameters

x1	x-coordinate of line start
y1	y-coordinate of line start
x2	x-coordinate of line end
y2	y-coordinate of line end

Returns: angle in radians. Returned value is undefined if start and end point are the same.

Definition at line 837 of file qgsgeometryutils.cpp.

◆ normalizedAngle()

double QgsGeometryUtils::normalizedAngle ( double angle )

static

Ensures that an angle is in the range 0 <= angle < 2 pi.

Parameters

angle angle in radians

Returns: equivalent angle within the range [0, 2 pi)

Definition at line 771 of file qgsgeometryutils.cpp.

◆ pointOnLineWithDistance()

QgsPointV2 QgsGeometryUtils::pointOnLineWithDistance	(	const QgsPointV2 &	startPoint,
		const QgsPointV2 &	directionPoint,
		double	distance
	)

static

Returns a point a specified distance toward a second point.

Definition at line 380 of file qgsgeometryutils.cpp.

◆ pointsFromWKT()

QgsPointSequenceV2 QgsGeometryUtils::pointsFromWKT	(	const QString &	wktCoordinateList,
		bool	is3D,
		bool	isMeasure
	)

static

Returns a list of points contained in a WKT string.

Definition at line 610 of file qgsgeometryutils.cpp.

◆ pointsToGML2()

QDomElement QgsGeometryUtils::pointsToGML2	(	const QgsPointSequenceV2 &	points,
		QDomDocument &	doc,
		int	precision,
		const QString &	ns
	)

static

Returns a gml::coordinates DOM element.

Definition at line 713 of file qgsgeometryutils.cpp.

◆ pointsToGML3()

QDomElement QgsGeometryUtils::pointsToGML3	(	const QgsPointSequenceV2 &	points,
		QDomDocument &	doc,
		int	precision,
		const QString &	ns,
		bool	is3D
	)

static

Returns a gml::posList DOM element.

Definition at line 737 of file qgsgeometryutils.cpp.

◆ pointsToJSON()

QString QgsGeometryUtils::pointsToJSON	(	const QgsPointSequenceV2 &	points,
		int	precision
	)

static

Returns a geoJSON coordinates string.

Definition at line 756 of file qgsgeometryutils.cpp.

◆ pointsToWKB()

void QgsGeometryUtils::pointsToWKB	(	QgsWkbPtr &	wkb,
		const QgsPointSequenceV2 &	points,
		bool	is3D,
		bool	isMeasure
	)

static

Returns a LinearRing { uint32 numPoints; Point points[numPoints]; }.

Definition at line 677 of file qgsgeometryutils.cpp.

◆ pointsToWKT()

QString QgsGeometryUtils::pointsToWKT	(	const QgsPointSequenceV2 &	points,
		int	precision,
		bool	is3D,
		bool	isMeasure
	)

static

Returns a WKT coordinate list.

Definition at line 694 of file qgsgeometryutils.cpp.

◆ projPointOnSegment()

static QgsPointV2 QgsGeometryUtils::projPointOnSegment	(	const QgsPointV2 &	p,
		const QgsPointV2 &	s1,
		const QgsPointV2 &	s2
	)

inlinestatic

Project the point on a segment.

Parameters

p	The point
s1	The segment start point
s2	The segment end point

Returns: The projection of the point on the segment

Definition at line 110 of file qgsgeometryutils.h.

◆ segmentIntersection()

bool QgsGeometryUtils::segmentIntersection	(	const QgsPointV2 &	p1,
		const QgsPointV2 &	p2,
		const QgsPointV2 &	q1,
		const QgsPointV2 &	q2,
		QgsPointV2 &	inter,
		double	tolerance
	)

static

Compute the intersection between two segments.

Parameters

p1	First segment start point
p2	First segment end point
q1	Second segment start point
q2	Second segment end point
inter	Output parameter, the intersection point
tolerance	The tolerance to use

Returns: Whether the segments intersect

Definition at line 304 of file qgsgeometryutils.cpp.

◆ segmentMidPoint()

bool QgsGeometryUtils::segmentMidPoint	(	const QgsPointV2 &	p1,
		const QgsPointV2 &	p2,
		QgsPointV2 &	result,
		double	radius,
		const QgsPointV2 &	mousePos
	)

static

Calculates midpoint on circle passing through p1 and p2, closest to given coordinate.

Definition at line 547 of file qgsgeometryutils.cpp.

◆ sqrDistance2D()

double QgsGeometryUtils::sqrDistance2D	(	const QgsPointV2 &	pt1,
		const QgsPointV2 &	pt2
	)

static

Returns the squared 2D distance between two points.

Definition at line 244 of file qgsgeometryutils.cpp.

◆ sqrDistToLine()

double QgsGeometryUtils::sqrDistToLine	(	double	ptX,
		double	ptY,
		double	x1,
		double	y1,
		double	x2,
		double	y2,
		double &	minDistX,
		double &	minDistY,
		double	epsilon
	)

static

Returns the squared distance between a point and a line.

Definition at line 249 of file qgsgeometryutils.cpp.

◆ sweepAngle()

double QgsGeometryUtils::sweepAngle	(	double	centerX,
		double	centerY,
		double	x1,
		double	y1,
		double	x2,
		double	y2,
		double	x3,
		double	y3
	)

static

Calculates angle of a circular string part defined by pt1, pt2, pt3.

Definition at line 517 of file qgsgeometryutils.cpp.

◆ verticesAtDistance()

bool QgsGeometryUtils::verticesAtDistance	(	const QgsAbstractGeometryV2 &	geometry,
		double	distance,
		QgsVertexId &	previousVertex,
		QgsVertexId &	nextVertex
	)

static

Retrieves the vertices which are before and after the interpolated point at a specified distance along a linestring (or polygon boundary).

Parameters

geometry	line or polygon geometry
distance	distance to traverse along geometry
previousVertex	will be set to previous vertex ID
nextVertex	will be set to next vertex ID

Note: if the distance coincides exactly with a vertex, then both previousVertex and nextVertex will be set to this vertex

Returns: true if vertices were successfully retrieved

Note: added in QGIS 2.18

Definition at line 123 of file qgsgeometryutils.cpp.

◆ wktGetChildBlocks()

QStringList QgsGeometryUtils::wktGetChildBlocks	(	const QString &	wkt,
		const QString &	defaultType = `""`
	)

static

Parses a WKT string and returns of list of blocks contained in the WKT.

Parameters

wkt	WKT string in the format "TYPE1 (contents1), TYPE2 (TYPE3 (contents3), TYPE4 (contents4))"
defaultType	default geometry type for childen

Returns: list of WKT child block strings, eg List("TYPE1 (contents1)", "TYPE2 (TYPE3 (contents3), TYPE4 (contents4))")

Definition at line 794 of file qgsgeometryutils.cpp.

◆ wktReadBlock()

QPair< QgsWKBTypes::Type, QString > QgsGeometryUtils::wktReadBlock ( const QString & wkt )

static

Parses a WKT block of the format "TYPE( contents )" and returns a pair of geometry type to contents ("Pair(wkbType, "contents")")

Definition at line 785 of file qgsgeometryutils.cpp.

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

/tmp/buildd/qgis-2.18.21+99unstable/src/core/geometry/qgsgeometryutils.h
/tmp/buildd/qgis-2.18.21+99unstable/src/core/geometry/qgsgeometryutils.cpp

Classes

Public Types

Static Public Member Functions

Detailed Description

Member Enumeration Documentation

◆ componentType

Member Function Documentation

◆ adjacentVertices()

◆ angleOnCircle()

◆ averageAngle() [1/2]

◆ averageAngle() [2/2]

◆ ccwAngle()

◆ circleAngleBetween()

◆ circleCenterRadius()

◆ circleClockwise()

◆ circleLength()

◆ circleTangentDirection()

◆ closestSegmentFromComponents()

◆ closestVertex()

◆ distanceToVertex()

◆ extractLineStrings()

◆ getSelfIntersections()

◆ leftOfLine()

◆ lineAngle()

◆ lineIntersection()

◆ linePerpendicularAngle()

◆ normalizedAngle()

◆ pointOnLineWithDistance()

◆ pointsFromWKT()

◆ pointsToGML2()

◆ pointsToGML3()

◆ pointsToJSON()

◆ pointsToWKB()

◆ pointsToWKT()

◆ projPointOnSegment()

◆ segmentIntersection()

◆ segmentMidPoint()

◆ sqrDistance2D()

◆ sqrDistToLine()

◆ sweepAngle()

◆ verticesAtDistance()

◆ wktGetChildBlocks()

◆ wktReadBlock()