QGIS API Documentation  3.17.0-Master (8af46bc54f)
Classes | Public Types | Static Public Member Functions | List of all members
QgsGeometryUtils Class Reference

Contains various geometry utility functions. More...

#include <qgsgeometryutils.h>

Classes

struct  SelfIntersection
 

Public Types

enum  ComponentType { Vertex, Ring, Part }
 

Static Public Member Functions

static double angleBetweenThreePoints (double x1, double y1, double x2, double y2, double x3, double y3) SIP_HOLDGIL
 Calculates the angle between the lines AB and BC, where AB and BC described by points a, b and b, c. More...
 
static bool angleOnCircle (double angle, double angle1, double angle2, double angle3) SIP_HOLDGIL
 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) SIP_HOLDGIL
 Calculates the average angle (in radians) between the two linear segments from (x1, y1) to (x2, y2) and (x2, y2) to (x3, y3). More...
 
static double averageAngle (double a1, double a2) SIP_HOLDGIL
 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) SIP_HOLDGIL
 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) SIP_HOLDGIL
 Returns true if, in a circle, angle is between angle1 and angle2. More...
 
static void circleCenterRadius (const QgsPoint &pt1, const QgsPoint &pt2, const QgsPoint &pt3, double &radius, double &centerX, double &centerY) SIP_HOLDGIL
 Returns radius and center of the circle through pt1, pt2, pt3. More...
 
static int circleCircleInnerTangents (const QgsPointXY &center1, double radius1, const QgsPointXY &center2, double radius2, QgsPointXY &line1P1, QgsPointXY &line1P2, QgsPointXY &line2P1, QgsPointXY &line2P2) SIP_HOLDGIL
 Calculates the inner tangent points for two circles, centered at center1 and center2 and with radii of radius1 and radius2 respectively. More...
 
static int circleCircleIntersections (QgsPointXY center1, double radius1, QgsPointXY center2, double radius2, QgsPointXY &intersection1, QgsPointXY &intersection2) SIP_HOLDGIL
 Calculates the intersections points between the circle with center center1 and radius radius1 and the circle with center center2 and radius radius2. More...
 
static int circleCircleOuterTangents (const QgsPointXY &center1, double radius1, const QgsPointXY &center2, double radius2, QgsPointXY &line1P1, QgsPointXY &line1P2, QgsPointXY &line2P1, QgsPointXY &line2P2) SIP_HOLDGIL
 Calculates the outer tangent points for two circles, centered at center1 and center2 and with radii of radius1 and radius2 respectively. More...
 
static bool circleClockwise (double angle1, double angle2, double angle3) SIP_HOLDGIL
 Returns true if the circle defined by three angles is ordered clockwise. More...
 
static double circleLength (double x1, double y1, double x2, double y2, double x3, double y3) SIP_HOLDGIL
 Length of a circular string segment defined by pt1, pt2, pt3. More...
 
static double circleTangentDirection (const QgsPoint &tangentPoint, const QgsPoint &cp1, const QgsPoint &cp2, const QgsPoint &cp3) SIP_HOLDGIL
 Calculates the direction angle of a circle tangent (clockwise from north in radians) More...
 
static QgsPoint closestPoint (const QgsAbstractGeometry &geometry, const QgsPoint &point)
 Returns the nearest point on a segment of a geometry for the specified point. More...
 
template<class T >
static double closestSegmentFromComponents (T &container, ComponentType ctype, const QgsPoint &pt, QgsPoint &segmentPt, QgsVertexId &vertexAfter, int *leftOf, double epsilon)
 
static QgsPoint closestVertex (const QgsAbstractGeometry &geom, const QgsPoint &pt, QgsVertexId &id)
 Returns the closest vertex to a geometry for a specified point. More...
 
static void coefficients (const QgsPoint &pt1, const QgsPoint &pt2, double &a, double &b, double &c) SIP_HOLDGIL
 Returns the coefficients (a, b, c for equation "ax + by + c = 0") of a line defined by points pt1 and pt2. More...
 
static double distanceToVertex (const QgsAbstractGeometry &geom, QgsVertexId id)
 Returns the distance along a geometry from its first vertex to the specified vertex. More...
 
static QVector< QgsLineString * > extractLineStrings (const QgsAbstractGeometry *geom)
 Returns list of linestrings extracted from the passed geometry. More...
 
static double gradient (const QgsPoint &pt1, const QgsPoint &pt2) SIP_HOLDGIL
 Returns the gradient of a line defined by points pt1 and pt2. More...
 
static double interpolateArcValue (double angle, double a1, double a2, double a3, double zm1, double zm2, double zm3) SIP_HOLDGIL
 Interpolate a value at given angle on circular arc given values (zm1, zm2, zm3) at three different angles (a1, a2, a3). More...
 
static QgsPoint interpolatePointOnArc (const QgsPoint &pt1, const QgsPoint &pt2, const QgsPoint &pt3, double distance) SIP_HOLDGIL
 Interpolates a point on an arc defined by three points, pt1, pt2 and pt3. More...
 
static QgsPointXY interpolatePointOnLine (double x1, double y1, double x2, double y2, double fraction) SIP_HOLDGIL
 Interpolates the position of a point a fraction of the way along the line from (x1, y1) to (x2, y2). More...
 
static QgsPoint interpolatePointOnLine (const QgsPoint &p1, const QgsPoint &p2, double fraction) SIP_HOLDGIL
 Interpolates the position of a point a fraction of the way along the line from p1 to p2. More...
 
static QgsPointXY interpolatePointOnLineByValue (double x1, double y1, double v1, double x2, double y2, double v2, double value) SIP_HOLDGIL
 Interpolates the position of a point along the line from (x1, y1) to (x2, y2). More...
 
static int leftOfLine (const double x, const double y, const double x1, const double y1, const double x2, const double y2) SIP_HOLDGIL
 Returns a value < 0 if the point (x, y) is left of the line from (x1, y1) -> (x2, y2). More...
 
static int leftOfLine (const QgsPoint &point, const QgsPoint &p1, const QgsPoint &p2) SIP_HOLDGIL
 Returns a value < 0 if the point point is left of the line from p1 -> p2. More...
 
static double lineAngle (double x1, double y1, double x2, double y2) SIP_HOLDGIL
 Calculates the direction of line joining two points in radians, clockwise from the north direction. More...
 
static bool lineCircleIntersection (const QgsPointXY &center, double radius, const QgsPointXY &linePoint1, const QgsPointXY &linePoint2, QgsPointXY &intersection) SIP_HOLDGIL
 Compute the intersection of a line and a circle. More...
 
static bool lineIntersection (const QgsPoint &p1, QgsVector v1, const QgsPoint &p2, QgsVector v2, QgsPoint &intersection) SIP_HOLDGIL
 Computes the intersection between two lines. More...
 
static double linePerpendicularAngle (double x1, double y1, double x2, double y2) SIP_HOLDGIL
 Calculates the perpendicular angle to a line joining two points. More...
 
static bool linesIntersection3D (const QgsVector3D &La1, const QgsVector3D &La2, const QgsVector3D &Lb1, const QgsVector3D &Lb2, QgsVector3D &intersection) SIP_HOLDGIL
 An algorithm to calculate an (approximate) intersection of two lines in 3D. More...
 
static QgsPoint midpoint (const QgsPoint &pt1, const QgsPoint &pt2) SIP_HOLDGIL
 Returns a middle point between points pt1 and pt2. More...
 
static double normalizedAngle (double angle) SIP_HOLDGIL
 Ensures that an angle is in the range 0 <= angle < 2 pi. More...
 
static QgsLineString perpendicularSegment (const QgsPoint &p, const QgsPoint &s1, const QgsPoint &s2) SIP_HOLDGIL
 Create a perpendicular line segment from p to segment [s1, s2]. More...
 
static bool pointContinuesArc (const QgsPoint &a1, const QgsPoint &a2, const QgsPoint &a3, const QgsPoint &b, double distanceTolerance, double pointSpacingAngleTolerance) SIP_HOLDGIL
 Returns true if point b is on the arc formed by points a1, a2, and a3, but not within that arc portion already described by a1, a2 and a3. More...
 
static QgsPoint pointOnLineWithDistance (const QgsPoint &startPoint, const QgsPoint &directionPoint, double distance) SIP_HOLDGIL
 Returns a point a specified distance toward a second point. More...
 
static void pointOnLineWithDistance (double x1, double y1, double x2, double y2, double distance, double &x, double &y, double *z1=nullptr, double *z2=nullptr, double *z=nullptr, double *m1=nullptr, double *m2=nullptr, double *m=nullptr)
 Calculates the point a specified distance from (x1, y1) toward a second point (x2, y2). More...
 
static QgsPointSequence pointsFromWKT (const QString &wktCoordinateList, bool is3D, bool isMeasure)
 Returns a list of points contained in a WKT string. More...
 
static QDomElement pointsToGML2 (const QgsPointSequence &points, QDomDocument &doc, int precision, const QString &ns, QgsAbstractGeometry::AxisOrder axisOrder=QgsAbstractGeometry::AxisOrder::XY)
 Returns a gml::coordinates DOM element. More...
 
static QDomElement pointsToGML3 (const QgsPointSequence &points, QDomDocument &doc, int precision, const QString &ns, bool is3D, QgsAbstractGeometry::AxisOrder axisOrder=QgsAbstractGeometry::AxisOrder::XY)
 Returns a gml::posList DOM element. More...
 
static QString pointsToJSON (const QgsPointSequence &points, int precision)
 Returns a geoJSON coordinates string. More...
 
static json pointsToJson (const QgsPointSequence &points, int precision)
 Returns coordinates as json object. More...
 
static void pointsToWKB (QgsWkbPtr &wkb, const QgsPointSequence &points, bool is3D, bool isMeasure)
 Returns a LinearRing { uint32 numPoints; Point points[numPoints]; }. More...
 
static QString pointsToWKT (const QgsPointSequence &points, int precision, bool is3D, bool isMeasure)
 Returns a WKT coordinate list. More...
 
static QgsPoint projectPointOnSegment (const QgsPoint &p, const QgsPoint &s1, const QgsPoint &s2) SIP_HOLDGIL
 Project the point on a segment. More...
 
static bool segmentIntersection (const QgsPoint &p1, const QgsPoint &p2, const QgsPoint &q1, const QgsPoint &q2, QgsPoint &intersectionPoint, bool &isIntersection, double tolerance=1e-8, bool acceptImproperIntersection=false) SIP_HOLDGIL
 Compute the intersection between two segments. More...
 
static void segmentizeArc (const QgsPoint &p1, const QgsPoint &p2, const QgsPoint &p3, QgsPointSequence &points, double tolerance=M_PI_2/90, QgsAbstractGeometry::SegmentationToleranceType toleranceType=QgsAbstractGeometry::MaximumAngle, bool hasZ=false, bool hasM=false)
 Convert circular arc defined by p1, p2, p3 (p1/p3 being start resp. More...
 
static bool segmentMidPoint (const QgsPoint &p1, const QgsPoint &p2, QgsPoint &result, double radius, const QgsPoint &mousePos) SIP_HOLDGIL
 Calculates midpoint on circle passing through p1 and p2, closest to the given coordinate mousePos. More...
 
static QgsPoint segmentMidPointFromCenter (const QgsPoint &p1, const QgsPoint &p2, const QgsPoint &center, bool useShortestArc=true) SIP_HOLDGIL
 Calculates the midpoint on the circle passing through p1 and p2, with the specified center coordinate. More...
 
static int segmentSide (const QgsPoint &pt1, const QgsPoint &pt3, const QgsPoint &pt2) SIP_HOLDGIL
 For line defined by points pt1 and pt3, find out on which side of the line is point pt3. More...
 
static QVector< SelfIntersectionselfIntersections (const QgsAbstractGeometry *geom, int part, int ring, double tolerance)
 Find self intersections in a polyline. More...
 
static bool setZValueFromPoints (const QgsPointSequence &points, QgsPoint &point)
 A Z dimension is added to point if one of the point in the list points is in 3D. More...
 
static double skewLinesDistance (const QgsVector3D &P1, const QgsVector3D &P12, const QgsVector3D &P2, const QgsVector3D &P22) SIP_HOLDGIL
 An algorithm to calculate the shortest distance between two skew lines. More...
 
static bool skewLinesProjection (const QgsVector3D &P1, const QgsVector3D &P12, const QgsVector3D &P2, const QgsVector3D &P22, QgsVector3D &X1, double epsilon=0.0001) SIP_HOLDGIL
 A method to project one skew line onto another. More...
 
static double sqrDistance2D (const QgsPoint &pt1, const QgsPoint &pt2) SIP_HOLDGIL
 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) SIP_HOLDGIL
 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) SIP_HOLDGIL
 Calculates angle of a circular string part defined by pt1, pt2, pt3. More...
 
static bool tangentPointAndCircle (const QgsPointXY &center, double radius, const QgsPointXY &p, QgsPointXY &pt1, QgsPointXY &pt2) SIP_HOLDGIL
 Calculates the tangent points between the circle with the specified center and radius and the point p. More...
 
static double triangleArea (double aX, double aY, double bX, double bY, double cX, double cY) SIP_HOLDGIL
 Returns the area of the triangle denoted by the points (aX, aY), (bX, bY) and (cX, cY). More...
 
static bool verticesAtDistance (const QgsAbstractGeometry &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 void weightedPointInTriangle (double aX, double aY, double bX, double bY, double cX, double cY, double weightB, double weightC, double &pointX, double &pointY) SIP_HOLDGIL
 Returns a weighted point inside the triangle denoted by the points (aX, aY), (bX, bY) and (cX, cY). More...
 
static QStringList wktGetChildBlocks (const QString &wkt, const QString &defaultType=QString())
 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.

Since
QGIS 2.10

Definition at line 37 of file qgsgeometryutils.h.

Member Enumeration Documentation

◆ ComponentType

Note
not available in Python bindings
Enumerator
Vertex 
Ring 
Part 

Definition at line 731 of file qgsgeometryutils.h.

Member Function Documentation

◆ angleBetweenThreePoints()

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

Calculates the angle between the lines AB and BC, where AB and BC described by points a, b and b, c.

Parameters
x1x-coordinate of point a
y1y-coordinate of point a
x2x-coordinate of point b
y2y-coordinate of point b
x3x-coordinate of point c
y3y-coordinate of point c
Returns
angle between lines in radians. Returned value is undefined if two or more points are equal.

Definition at line 1507 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 749 of file qgsgeometryutils.cpp.

◆ averageAngle() [1/2]

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

Calculates the average angle (in radians) between the two linear segments from (x1, y1) to (x2, y2) and (x2, y2) to (x3, y3).

Definition at line 1521 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
a1first angle (in radians)
a2second angle (in radians)
Returns
average angle (in radians)

Definition at line 1529 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 659 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 723 of file qgsgeometryutils.cpp.

◆ circleCenterRadius()

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

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

Definition at line 673 of file qgsgeometryutils.cpp.

◆ circleCircleInnerTangents()

int QgsGeometryUtils::circleCircleInnerTangents ( const QgsPointXY center1,
double  radius1,
const QgsPointXY center2,
double  radius2,
QgsPointXY line1P1,
QgsPointXY line1P2,
QgsPointXY line2P1,
QgsPointXY line2P2 
)
static

Calculates the inner tangent points for two circles, centered at center1 and center2 and with radii of radius1 and radius2 respectively.

The inner tangent points correspond to the points at which the two lines which are drawn so that they are tangential to both circles and are crossing each other.

The first tangent line is described by the points stored in line1P1 and line1P2, and the second line is described by the points stored in line2P1 and line2P2.

Returns the number of tangents (either 0 or 2).

Since
QGIS 3.6

Definition at line 499 of file qgsgeometryutils.cpp.

◆ circleCircleIntersections()

int QgsGeometryUtils::circleCircleIntersections ( QgsPointXY  center1,
double  radius1,
QgsPointXY  center2,
double  radius2,
QgsPointXY intersection1,
QgsPointXY intersection2 
)
static

Calculates the intersections points between the circle with center center1 and radius radius1 and the circle with center center2 and radius radius2.

If found, the intersection points will be stored in intersection1 and intersection2.

Returns
number of intersection points found.
Since
QGIS 3.2

Definition at line 375 of file qgsgeometryutils.cpp.

◆ circleCircleOuterTangents()

int QgsGeometryUtils::circleCircleOuterTangents ( const QgsPointXY center1,
double  radius1,
const QgsPointXY center2,
double  radius2,
QgsPointXY line1P1,
QgsPointXY line1P2,
QgsPointXY line2P1,
QgsPointXY line2P2 
)
static

Calculates the outer tangent points for two circles, centered at center1 and center2 and with radii of radius1 and radius2 respectively.

The outer tangent points correspond to the points at which the two lines which are drawn so that they are tangential to both circles touch the circles.

The first tangent line is described by the points stored in line1P1 and line1P2, and the second line is described by the points stored in line2P1 and line2P2.

Returns the number of tangents (either 0 or 2).

Since
QGIS 3.2

Definition at line 463 of file qgsgeometryutils.cpp.

◆ circleClockwise()

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

Returns true if the circle defined by three angles is ordered clockwise.

The angles are defined counter-clockwise from the origin, i.e. using Euclidean angles as opposed to geographic "North up" angles.

Definition at line 711 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 755 of file qgsgeometryutils.cpp.

◆ circleTangentDirection()

double QgsGeometryUtils::circleTangentDirection ( const QgsPoint tangentPoint,
const QgsPoint cp1,
const QgsPoint cp2,
const QgsPoint cp3 
)
static

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

Definition at line 853 of file qgsgeometryutils.cpp.

◆ closestPoint()

QgsPoint QgsGeometryUtils::closestPoint ( const QgsAbstractGeometry geometry,
const QgsPoint point 
)
static

Returns the nearest point on a segment of a geometry for the specified point.

The z and m values will be linearly interpolated between the two neighbouring vertices.

Definition at line 101 of file qgsgeometryutils.cpp.

◆ closestSegmentFromComponents()

template<class T >
static double QgsGeometryUtils::closestSegmentFromComponents ( T &  container,
ComponentType  ctype,
const QgsPoint pt,
QgsPoint segmentPt,
QgsVertexId vertexAfter,
int *  leftOf,
double  epsilon 
)
inlinestatic
Note
not available in Python bindings

Definition at line 739 of file qgsgeometryutils.h.

◆ closestVertex()

QgsPoint QgsGeometryUtils::closestVertex ( const QgsAbstractGeometry geom,
const QgsPoint 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 67 of file qgsgeometryutils.cpp.

◆ coefficients()

void QgsGeometryUtils::coefficients ( const QgsPoint pt1,
const QgsPoint pt2,
double &  a,
double &  b,
double &  c 
)
static

Returns the coefficients (a, b, c for equation "ax + by + c = 0") of a line defined by points pt1 and pt2.

Parameters
pt1first point.
pt2second point.
aOutput parameter, a coefficient of the equation.
bOutput parameter, b coefficient of the equation.
cOutput parameter, c coefficient of the equation.
Since
QGIS 3.0

Definition at line 1439 of file qgsgeometryutils.cpp.

◆ distanceToVertex()

double QgsGeometryUtils::distanceToVertex ( const QgsAbstractGeometry geom,
QgsVertexId  id 
)
static

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

Parameters
geomgeometry
idvertex id to find distance to
Returns
distance to vertex (following geometry)
Since
QGIS 2.16

Definition at line 134 of file qgsgeometryutils.cpp.

◆ extractLineStrings()

QVector< QgsLineString * > QgsGeometryUtils::extractLineStrings ( const QgsAbstractGeometry geom)
static

Returns list of linestrings extracted from the passed geometry.

The returned objects have to be deleted by the caller.

Definition at line 31 of file qgsgeometryutils.cpp.

◆ gradient()

double QgsGeometryUtils::gradient ( const QgsPoint pt1,
const QgsPoint pt2 
)
static

Returns the gradient of a line defined by points pt1 and pt2.

Parameters
pt1first point.
pt2second point.
Returns
The gradient of this linear entity, or infinity if vertical
Since
QGIS 3.0

Definition at line 1427 of file qgsgeometryutils.cpp.

◆ interpolateArcValue()

double QgsGeometryUtils::interpolateArcValue ( double  angle,
double  a1,
double  a2,
double  a3,
double  zm1,
double  zm2,
double  zm3 
)
static

Interpolate a value at given angle on circular arc given values (zm1, zm2, zm3) at three different angles (a1, a2, a3).

Since
3.0

Definition at line 1079 of file qgsgeometryutils.cpp.

◆ interpolatePointOnArc()

QgsPoint QgsGeometryUtils::interpolatePointOnArc ( const QgsPoint pt1,
const QgsPoint pt2,
const QgsPoint pt3,
double  distance 
)
static

Interpolates a point on an arc defined by three points, pt1, pt2 and pt3.

The arc will be interpolated by the specified distance from pt1.

Any z or m values present in the points will also be linearly interpolated in the output.

Since
QGIS 3.4

Definition at line 634 of file qgsgeometryutils.cpp.

◆ interpolatePointOnLine() [1/2]

QgsPointXY QgsGeometryUtils::interpolatePointOnLine ( double  x1,
double  y1,
double  x2,
double  y2,
double  fraction 
)
static

Interpolates the position of a point a fraction of the way along the line from (x1, y1) to (x2, y2).

Usually the fraction should be between 0 and 1, where 0 represents the point at the start of the line (x1, y1) and 1 represents the end of the line (x2, y2). However, it is possible to use a fraction < 0 or > 1, in which case the returned point is extrapolated from the supplied line.

See also
interpolatePointOnLineByValue()
Since
QGIS 3.0.2

Definition at line 1411 of file qgsgeometryutils.cpp.

◆ interpolatePointOnLine() [2/2]

QgsPoint QgsGeometryUtils::interpolatePointOnLine ( const QgsPoint p1,
const QgsPoint p2,
double  fraction 
)
static

Interpolates the position of a point a fraction of the way along the line from p1 to p2.

Usually the fraction should be between 0 and 1, where 0 represents the point at the start of the line (p1) and 1 represents the end of the line (p2). However, it is possible to use a fraction < 0 or > 1, in which case the returned point is extrapolated from the supplied line.

Any Z or M values present in the input points will also be interpolated and present in the returned point.

See also
interpolatePointOnLineByValue()
Since
QGIS 3.0.2

Definition at line 1401 of file qgsgeometryutils.cpp.

◆ interpolatePointOnLineByValue()

QgsPointXY QgsGeometryUtils::interpolatePointOnLineByValue ( double  x1,
double  y1,
double  v1,
double  x2,
double  y2,
double  v2,
double  value 
)
static

Interpolates the position of a point along the line from (x1, y1) to (x2, y2).

The position is interpolated using a supplied target value and the value at the start of the line (v1) and end of the line (v2). The returned point will be linearly interpolated to match position corresponding to the target value.

See also
interpolatePointOnLine()
Since
QGIS 3.0.2

Definition at line 1418 of file qgsgeometryutils.cpp.

◆ leftOfLine() [1/2]

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

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

A positive return value indicates the point is to the right of the line.

If the return value is 0, then the test was unsuccessful (e.g. due to testing a point exactly on the line, or exactly in line with the segment) and the result is undefined.

Definition at line 589 of file qgsgeometryutils.cpp.

◆ leftOfLine() [2/2]

int QgsGeometryUtils::leftOfLine ( const QgsPoint point,
const QgsPoint p1,
const QgsPoint p2 
)
static

Returns a value < 0 if the point point is left of the line from p1 -> p2.

A positive return value indicates the point is to the right of the line.

If the return value is 0, then the test was unsuccessful (e.g. due to testing a point exactly on the line, or exactly in line with the segment) and the result is undefined.

Since
QGIS 3.6

Definition at line 584 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
x1x-coordinate of line start
y1y-coordinate of line start
x2x-coordinate of line end
y2y-coordinate of line end
Returns
angle in radians. Returned value is undefined if start and end point are the same.

Definition at line 1500 of file qgsgeometryutils.cpp.

◆ lineCircleIntersection()

bool QgsGeometryUtils::lineCircleIntersection ( const QgsPointXY center,
double  radius,
const QgsPointXY linePoint1,
const QgsPointXY linePoint2,
QgsPointXY intersection 
)
static

Compute the intersection of a line and a circle.

If the intersection has two solutions (points), the closest point to the initial intersection point is returned.

Parameters
centerthe center of the circle
radiusthe radius of the circle
linePoint1a first point on the line
linePoint2a second point on the line
intersectionthe initial point and the returned intersection point
Returns
true if an intersection has been found

Definition at line 321 of file qgsgeometryutils.cpp.

◆ lineIntersection()

bool QgsGeometryUtils::lineIntersection ( const QgsPoint p1,
QgsVector  v1,
const QgsPoint p2,
QgsVector  v2,
QgsPoint intersection 
)
static

Computes the intersection between two lines.

Z dimension is supported and is retrieved from the first 3D point amongst p1 and p2.

Parameters
p1Point on the first line
v1Direction vector of the first line
p2Point on the second line
v2Direction vector of the second line
intersectionOutput parameter, the intersection point
Returns
Whether the lines intersect

Definition at line 242 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
x1x-coordinate of line start
y1y-coordinate of line start
x2x-coordinate of line end
y2y-coordinate of line end
Returns
angle in radians. Returned value is undefined if start and end point are the same.

Definition at line 1514 of file qgsgeometryutils.cpp.

◆ linesIntersection3D()

bool QgsGeometryUtils::linesIntersection3D ( const QgsVector3D La1,
const QgsVector3D La2,
const QgsVector3D Lb1,
const QgsVector3D Lb2,
QgsVector3D intersection 
)
static

An algorithm to calculate an (approximate) intersection of two lines in 3D.

Parameters
La1is the first point on the first line,
La2is the second point on the first line,
Lb1is the first point on the second line,
Lb2is the second point on the second line,
intersectionis the result intersection, of it can be found.
Returns
true if the intersection can be found, false - otherwise.

Example

# (True, PyQt5.QtGui.QgsVector3D(2.0, 0.0, 0.0))
# (True, PyQt5.QtGui.QgsVector3D(2.0, 0.0, 0.0))
# (True, PyQt5.QtGui.QgsVector3D(0.0, 0.0, 0.0))
# (True, PyQt5.QtGui.QgsVector3D(0.0, 0.0, 0.0))
# (False, PyQt5.QtGui.QgsVector3D(0.0, 0.0, 0.0))
# (False, PyQt5.QtGui.QgsVector3D(0.0, 0.0, 0.0))
# (True, PyQt5.QtGui.QgsVector3D(3.0, 3.0, 0.0))
# (True, PyQt5.QtGui.QgsVector3D(3.0, 3.0, 0.0))
# (True, PyQt5.QtGui.QgsVector3D(2.5, 2.5, 2.5))
# (True, PyQt5.QtGui.QgsVector3D(2.5, 2.5, 2.5))
# (True, PyQt5.QtGui.QgsVector3D(0.0, 5.0, 5.0))

Definition at line 1610 of file qgsgeometryutils.cpp.

◆ midpoint()

QgsPoint QgsGeometryUtils::midpoint ( const QgsPoint pt1,
const QgsPoint pt2 
)
static

Returns a middle point between points pt1 and pt2.

Z value is computed if one of this point have Z. M value is computed if one of this point have M.

Parameters
pt1first point.
pt2second point.
Returns
New point at middle between points pt1 and pt2.

Example

p = QgsPoint( 4, 6 ) # 2D point
pr = midpoint ( p, QgsPoint( 2, 2 ) )
# pr is a 2D point: 'Point (3 4)'
pr = midpoint ( p, QgsPoint( QgsWkbTypes.PointZ, 2, 2, 2 ) )
# pr is a 3D point: 'PointZ (3 4 1)'
pr = midpoint ( p, QgsPoint( QgsWkbTypes.PointM, 2, 2, 0, 2 ) )
# pr is a 3D point: 'PointM (3 4 1)'
pr = midpoint ( p, QgsPoint( QgsWkbTypes.PointZM, 2, 2, 2, 2 ) )
# pr is a 3D point: 'PointZM (3 4 1 1)'
Since
QGIS 3.0

Definition at line 1376 of file qgsgeometryutils.cpp.

◆ normalizedAngle()

double QgsGeometryUtils::normalizedAngle ( double  angle)
static

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

Parameters
angleangle in radians
Returns
equivalent angle within the range [0, 2 pi)

Definition at line 1292 of file qgsgeometryutils.cpp.

◆ perpendicularSegment()

QgsLineString QgsGeometryUtils::perpendicularSegment ( const QgsPoint p,
const QgsPoint s1,
const QgsPoint s2 
)
static

Create a perpendicular line segment from p to segment [s1, s2].

Parameters
pThe point
s1The segment start point
s2The segment end point
Returns
A line (segment) from p to perpendicular point on segment [s1, s2]

Definition at line 1462 of file qgsgeometryutils.cpp.

◆ pointContinuesArc()

bool QgsGeometryUtils::pointContinuesArc ( const QgsPoint a1,
const QgsPoint a2,
const QgsPoint a3,
const QgsPoint b,
double  distanceTolerance,
double  pointSpacingAngleTolerance 
)
static

Returns true if point b is on the arc formed by points a1, a2, and a3, but not within that arc portion already described by a1, a2 and a3.

The distanceTolerance specifies the maximum deviation allowed between the original location of point and where it would fall on the candidate arc.

This method only consider a segments as continuing an arc if the points are all regularly spaced on the candidate arc. The pointSpacingAngleTolerance parameter specifies the maximum angular deviation (in radians) allowed when testing for regular point spacing.

Note
The API is considered EXPERIMENTAL and can be changed without a notice
Since
QGIS 3.14

Definition at line 878 of file qgsgeometryutils.cpp.

◆ pointOnLineWithDistance() [1/2]

QgsPoint QgsGeometryUtils::pointOnLineWithDistance ( const QgsPoint startPoint,
const QgsPoint directionPoint,
double  distance 
)
static

Returns a point a specified distance toward a second point.

Definition at line 600 of file qgsgeometryutils.cpp.

◆ pointOnLineWithDistance() [2/2]

void QgsGeometryUtils::pointOnLineWithDistance ( double  x1,
double  y1,
double  x2,
double  y2,
double  distance,
double &  x,
double &  y,
double *  z1 = nullptr,
double *  z2 = nullptr,
double *  z = nullptr,
double *  m1 = nullptr,
double *  m2 = nullptr,
double *  m = nullptr 
)
static

Calculates the point a specified distance from (x1, y1) toward a second point (x2, y2).

Optionally, interpolated z and m values can be obtained by specifying the z1, z2 and z arguments and/or the m1, m2, m arguments.

Note
Not available in Python bindings
Since
QGIS 3.4

Definition at line 607 of file qgsgeometryutils.cpp.

◆ pointsFromWKT()

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

Returns a list of points contained in a WKT string.

Note
not available in Python bindings

Definition at line 1099 of file qgsgeometryutils.cpp.

◆ pointsToGML2()

QDomElement QgsGeometryUtils::pointsToGML2 ( const QgsPointSequence points,
QDomDocument &  doc,
int  precision,
const QString &  ns,
QgsAbstractGeometry::AxisOrder  axisOrder = QgsAbstractGeometry::AxisOrder::XY 
)
static

Returns a gml::coordinates DOM element.

Note
not available in Python bindings

Definition at line 1210 of file qgsgeometryutils.cpp.

◆ pointsToGML3()

QDomElement QgsGeometryUtils::pointsToGML3 ( const QgsPointSequence points,
QDomDocument &  doc,
int  precision,
const QString &  ns,
bool  is3D,
QgsAbstractGeometry::AxisOrder  axisOrder = QgsAbstractGeometry::AxisOrder::XY 
)
static

Returns a gml::posList DOM element.

Note
not available in Python bindings

Definition at line 1237 of file qgsgeometryutils.cpp.

◆ pointsToJSON()

QString QgsGeometryUtils::pointsToJSON ( const QgsPointSequence points,
int  precision 
)
static

Returns a geoJSON coordinates string.

Note
not available in Python bindings

Definition at line 1259 of file qgsgeometryutils.cpp.

◆ pointsToJson()

json QgsGeometryUtils::pointsToJson ( const QgsPointSequence points,
int  precision 
)
static

Returns coordinates as json object.

Note
not available in Python bindings

Definition at line 1275 of file qgsgeometryutils.cpp.

◆ pointsToWKB()

void QgsGeometryUtils::pointsToWKB ( QgsWkbPtr wkb,
const QgsPointSequence points,
bool  is3D,
bool  isMeasure 
)
static

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

Note
not available in Python bindings

Definition at line 1174 of file qgsgeometryutils.cpp.

◆ pointsToWKT()

QString QgsGeometryUtils::pointsToWKT ( const QgsPointSequence points,
int  precision,
bool  is3D,
bool  isMeasure 
)
static

Returns a WKT coordinate list.

Note
not available in Python bindings

Definition at line 1191 of file qgsgeometryutils.cpp.

◆ projectPointOnSegment()

static QgsPoint QgsGeometryUtils::projectPointOnSegment ( const QgsPoint p,
const QgsPoint s1,
const QgsPoint s2 
)
inlinestatic

Project the point on a segment.

Parameters
pThe point
s1The segment start point
s2The segment end point
Returns
The projection of the point on the segment

Definition at line 238 of file qgsgeometryutils.h.

◆ segmentIntersection()

bool QgsGeometryUtils::segmentIntersection ( const QgsPoint p1,
const QgsPoint p2,
const QgsPoint q1,
const QgsPoint q2,
QgsPoint intersectionPoint,
bool &  isIntersection,
double  tolerance = 1e-8,
bool  acceptImproperIntersection = false 
)
static

Compute the intersection between two segments.

Parameters
p1First segment start point
p2First segment end point
q1Second segment start point
q2Second segment end point
intersectionPointOutput parameter, the intersection point
isIntersectionOutput parameter, return true if an intersection is found
toleranceThe tolerance to use
acceptImproperIntersectionBy default, this method returns true only if segments have proper intersection. If set true, returns also TRUE if segments have improper intersection (end of one segment on other segment ; continuous segments).
Returns
Whether the segments intersect

Example

ret = QgsGeometryUtils.segmentIntersection( QgsPoint( 0, 0 ), QgsPoint( 0, 1 ), QgsPoint( 1, 1 ), QgsPoint( 1, 0 ) )
ret[0], ret[1].asWkt(), ret[2]
# Whether the segments intersect, the intersection point, is intersect
# (False, 'Point (0 0)', False)
ret = QgsGeometryUtils.segmentIntersection( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 0, 5 ), QgsPoint( 1, 5 ) )
ret[0], ret[1].asWkt(), ret[2]
# (False, 'Point (0 5)', True)
ret = QgsGeometryUtils.segmentIntersection( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 0, 5 ), QgsPoint( 1, 5 ), acceptImproperIntersection=True )
ret[0], ret[1].asWkt(), ret[2]
# (True, 'Point (0 5)', True)
ret = QgsGeometryUtils.segmentIntersection( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 0, 2 ), QgsPoint( 1, 5 ) )
ret[0], ret[1].asWkt(), ret[2]
# (False, 'Point (0 2)', True)
ret = QgsGeometryUtils.segmentIntersection( QgsPoint( 0, 0 ), QgsPoint( 0, 5 ), QgsPoint( 0, 2 ), QgsPoint( 1, 5 ), acceptImproperIntersection=True )
ret[0], ret[1].asWkt(), ret[2]
# (True, 'Point (0 2)', True)
ret = QgsGeometryUtils.segmentIntersection( QgsPoint( 0, -5 ), QgsPoint( 0, 5 ), QgsPoint( 2, 0 ), QgsPoint( -1, 0 ) )
ret[0], ret[1].asWkt(), ret[2]
# (True, 'Point (0 0)', True)

Definition at line 261 of file qgsgeometryutils.cpp.

◆ segmentizeArc()

void QgsGeometryUtils::segmentizeArc ( const QgsPoint p1,
const QgsPoint p2,
const QgsPoint p3,
QgsPointSequence points,
double  tolerance = M_PI_2 / 90,
QgsAbstractGeometry::SegmentationToleranceType  toleranceType = QgsAbstractGeometry::MaximumAngle,
bool  hasZ = false,
bool  hasM = false 
)
static

Convert circular arc defined by p1, p2, p3 (p1/p3 being start resp.

end point, p2 lies on the arc) into a sequence of points.

Since
3.0

Definition at line 937 of file qgsgeometryutils.cpp.

◆ segmentMidPoint()

bool QgsGeometryUtils::segmentMidPoint ( const QgsPoint p1,
const QgsPoint p2,
QgsPoint result,
double  radius,
const QgsPoint mousePos 
)
static

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

Z dimension is supported and is retrieved from the first 3D point amongst p1 and p2.

See also
segmentMidPointFromCenter()

Definition at line 797 of file qgsgeometryutils.cpp.

◆ segmentMidPointFromCenter()

QgsPoint QgsGeometryUtils::segmentMidPointFromCenter ( const QgsPoint p1,
const QgsPoint p2,
const QgsPoint center,
bool  useShortestArc = true 
)
static

Calculates the midpoint on the circle passing through p1 and p2, with the specified center coordinate.

If useShortestArc is true, then the midpoint returned will be that corresponding to the shorter arc from p1 to p2. If it is false, the longer arc from p1 to p2 will be used (i.e. winding the other way around the circle).

See also
segmentMidPoint()
Since
QGIS 3.2

Definition at line 844 of file qgsgeometryutils.cpp.

◆ segmentSide()

int QgsGeometryUtils::segmentSide ( const QgsPoint pt1,
const QgsPoint pt3,
const QgsPoint pt2 
)
static

For line defined by points pt1 and pt3, find out on which side of the line is point pt3.

Returns -1 if pt3 on the left side, 1 if pt3 is on the right side or 0 if pt3 lies on the line.

Since
3.0

Definition at line 1058 of file qgsgeometryutils.cpp.

◆ selfIntersections()

QVector< QgsGeometryUtils::SelfIntersection > QgsGeometryUtils::selfIntersections ( const QgsAbstractGeometry geom,
int  part,
int  ring,
double  tolerance 
)
static

Find self intersections in a polyline.

Parameters
geomThe geometry to check
partThe part of the geometry to check
ringThe ring of the geometry part to check
toleranceThe tolerance to use
Returns
The list of self intersections
Note
not available in Python bindings
Since
QGIS 2.12

Definition at line 544 of file qgsgeometryutils.cpp.

◆ setZValueFromPoints()

bool QgsGeometryUtils::setZValueFromPoints ( const QgsPointSequence points,
QgsPoint point 
)
static

A Z dimension is added to point if one of the point in the list points is in 3D.

Moreover, the Z value of point is updated with.

Parameters
pointsList of points in which a 3D point is searched.
pointThe point to update with Z dimension and value.
Returns
true if the point is updated, false otherwise
Since
QGIS 3.0

Definition at line 1703 of file qgsgeometryutils.cpp.

◆ skewLinesDistance()

double QgsGeometryUtils::skewLinesDistance ( const QgsVector3D P1,
const QgsVector3D P12,
const QgsVector3D P2,
const QgsVector3D P22 
)
static

An algorithm to calculate the shortest distance between two skew lines.

Parameters
P1is the first point of the first line,
P12is the second point on the first line,
P2is the first point on the second line,
P22is the second point on the second line.
Returns
the shortest distance

Definition at line 1556 of file qgsgeometryutils.cpp.

◆ skewLinesProjection()

bool QgsGeometryUtils::skewLinesProjection ( const QgsVector3D P1,
const QgsVector3D P12,
const QgsVector3D P2,
const QgsVector3D P22,
QgsVector3D X1,
double  epsilon = 0.0001 
)
static

A method to project one skew line onto another.

Parameters
P1is a first point that belonds to first skew line,
P12is the second point that belongs to first skew line,
P2is the first point that belongs to second skew line,
P22is the second point that belongs to second skew line,
X1is the result projection point of line P2P22 onto line P1P12,
epsilonthe tolerance to use.
Returns
true if such point exists, false - otherwise.

Definition at line 1568 of file qgsgeometryutils.cpp.

◆ sqrDistance2D()

double QgsGeometryUtils::sqrDistance2D ( const QgsPoint pt1,
const QgsPoint pt2 
)
static

Returns the squared 2D distance between two points.

Definition at line 198 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 203 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 767 of file qgsgeometryutils.cpp.

◆ tangentPointAndCircle()

bool QgsGeometryUtils::tangentPointAndCircle ( const QgsPointXY center,
double  radius,
const QgsPointXY p,
QgsPointXY pt1,
QgsPointXY pt2 
)
static

Calculates the tangent points between the circle with the specified center and radius and the point p.

If found, the tangent points will be stored in pt1 and pt2.

Since
QGIS 3.2

Definition at line 439 of file qgsgeometryutils.cpp.

◆ triangleArea()

double QgsGeometryUtils::triangleArea ( double  aX,
double  aY,
double  bX,
double  bY,
double  cX,
double  cY 
)
static

Returns the area of the triangle denoted by the points (aX, aY), (bX, bY) and (cX, cY).

Since
QGIS 3.10

Definition at line 1679 of file qgsgeometryutils.cpp.

◆ verticesAtDistance()

bool QgsGeometryUtils::verticesAtDistance ( const QgsAbstractGeometry 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
geometryline or polygon geometry
distancedistance to traverse along geometry
previousVertexwill be set to previous vertex ID
nextVertexwill be set to next vertex ID
Returns
true if vertices were successfully retrieved
Note
if the distance coincides exactly with a vertex, then both previousVertex and nextVertex will be set to this vertex
Since
QGIS 3.0

Definition at line 153 of file qgsgeometryutils.cpp.

◆ weightedPointInTriangle()

void QgsGeometryUtils::weightedPointInTriangle ( double  aX,
double  aY,
double  bX,
double  bY,
double  cX,
double  cY,
double  weightB,
double  weightC,
double &  pointX,
double &  pointY 
)
static

Returns a weighted point inside the triangle denoted by the points (aX, aY), (bX, bY) and (cX, cY).

Parameters
aXx-coordinate of first vertex in triangle
aYy-coordinate of first vertex in triangle
bXx-coordinate of second vertex in triangle
bYy-coordinate of second vertex in triangle
cXx-coordinate of third vertex in triangle
cYy-coordinate of third vertex in triangle
weightBweighting factor along axis A-B (between 0 and 1)
weightCweighting factor along axis A-C (between 0 and 1)
pointXx-coordinate of generated point
pointYy-coordinate of generated point
Since
QGIS 3.10

Definition at line 1684 of file qgsgeometryutils.cpp.

◆ wktGetChildBlocks()

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

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

Parameters
wktWKT string in the format "TYPE1 (contents1), TYPE2 (TYPE3 (contents3), TYPE4 (contents4))"
defaultTypedefault geometry type for children
Returns
list of WKT child block strings, e.g., List("TYPE1 (contents1)", "TYPE2 (TYPE3 (contents3), TYPE4 (contents4))")
Note
not available in Python bindings

Definition at line 1340 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")")

Note
not available in Python bindings

Definition at line 1306 of file qgsgeometryutils.cpp.


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