QGIS API Documentation
3.8.0Zanzibar (11aff65)

Circle geometry type. More...
#include <qgscircle.h>
Public Member Functions  
QgsCircle ()  
QgsCircle (const QgsPoint ¢er, double radius, double azimuth=0)  
Constructs a circle by defining all the members. More...  
double  area () const override 
The area of the ellipse. More...  
QgsRectangle  boundingBox () const override 
Returns the minimal bounding box for the ellipse. More...  
bool  contains (const QgsPoint &point, double epsilon=1E8) const 
Returns true if the circle contains the point. More...  
int  innerTangents (const QgsCircle &other, QgsPointXY &line1P1, QgsPointXY &line1P2, QgsPointXY &line2P1, QgsPointXY &line2P2) const 
Calculates the inner tangent points between this circle and an other circle. More...  
int  intersections (const QgsCircle &other, QgsPoint &intersection1, QgsPoint &intersection2, bool useZ=false) const 
Calculates the intersections points between this circle and an other circle. More...  
QVector< QgsPoint >  northQuadrant () const 
The four quadrants of the ellipse. More...  
int  outerTangents (const QgsCircle &other, QgsPointXY &line1P1, QgsPointXY &line1P2, QgsPointXY &line2P1, QgsPointXY &line2P2) const 
Calculates the outer tangent points between this circle and an other circle. More...  
double  perimeter () const override 
The circumference of the ellipse using first approximation of Ramanujan. More...  
double  radius () const 
Returns the radius of the circle. More...  
void  setRadius (double radius) 
Sets the radius of the circle. More...  
void  setSemiMajorAxis (double semiMajorAxis) override 
Inherited method. More...  
void  setSemiMinorAxis (double semiMinorAxis) override 
Inherited method. More...  
bool  tangentToPoint (const QgsPointXY &p, QgsPointXY &pt1, QgsPointXY &pt2) const 
Calculates the tangent points between this circle and the point p. More...  
QgsCircularString *  toCircularString (bool oriented=false) const 
Returns a circular string from the circle. More...  
QString  toString (int pointPrecision=17, int radiusPrecision=17, int azimuthPrecision=2) const override 
returns a string representation of the ellipse. More...  
Public Member Functions inherited from QgsEllipse  
QgsEllipse ()=default  
Constructor for QgsEllipse. More...  
QgsEllipse (const QgsPoint ¢er, double semiMajorAxis, double semiMinorAxis, double azimuth=90)  
Constructs an ellipse by defining all the members. More...  
virtual  ~QgsEllipse ()=default 
double  azimuth () const 
Returns the azimuth. More...  
QgsPoint  center () const 
Returns the center point. More...  
virtual double  eccentricity () const 
The eccentricity of the ellipse. More...  
virtual QVector< QgsPoint >  foci () const 
Two foci of the ellipse. More...  
virtual double  focusDistance () const 
The distance between the center and each foci. More...  
virtual bool  isEmpty () const 
An ellipse is empty if axes are equal to 0. More...  
virtual bool  operator!= (const QgsEllipse &elp) const 
virtual bool  operator== (const QgsEllipse &elp) const 
virtual QgsPolygon *  orientedBoundingBox () const 
Returns the oriented minimal bounding box for the ellipse. More...  
virtual QgsPointSequence  points (unsigned int segments=36) const 
Returns a list of points with segmentation from segments. More...  
virtual QVector< QgsPoint >  quadrant () const 
The four quadrants of the ellipse. More...  
QgsPoint &  rcenter () 
Returns a reference to the center point of this ellipse. More...  
double  semiMajorAxis () const 
Returns the semimajor axis. More...  
double  semiMinorAxis () const 
Returns the semiminor axis. More...  
void  setAzimuth (double azimuth) 
Sets the azimuth (orientation). More...  
void  setCenter (const QgsPoint ¢er) 
Sets the center point. More...  
virtual QgsLineString *  toLineString (unsigned int segments=36) const 
Returns a segmented linestring. More...  
virtual QgsPolygon *  toPolygon (unsigned int segments=36) const 
Returns a segmented polygon. More...  
Static Public Member Functions  
static QgsCircle  from2Points (const QgsPoint &pt1, const QgsPoint &pt2) 
Constructs a circle by 2 points on the circle. More...  
static QgsCircle  from3Points (const QgsPoint &pt1, const QgsPoint &pt2, const QgsPoint &pt3, double epsilon=1E8) 
Constructs a circle by 3 points on the circle. More...  
static QgsCircle  from3Tangents (const QgsPoint &pt1_tg1, const QgsPoint &pt2_tg1, const QgsPoint &pt1_tg2, const QgsPoint &pt2_tg2, const QgsPoint &pt1_tg3, const QgsPoint &pt2_tg3, double epsilon=1E8) 
Constructs a circle by 3 tangents on the circle (aka inscribed circle of a triangle). More...  
static QgsCircle  fromCenterDiameter (const QgsPoint ¢er, double diameter, double azimuth=0) 
Constructs a circle by a center point and a diameter. More...  
static QgsCircle  fromCenterPoint (const QgsPoint ¢er, const QgsPoint &pt1) 
Constructs a circle by a center point and another point. More...  
static QgsCircle  fromExtent (const QgsPoint &pt1, const QgsPoint &pt2) 
Constructs a circle by an extent (aka bounding box / QgsRectangle). More...  
static QgsCircle  minimalCircleFrom3Points (const QgsPoint &pt1, const QgsPoint &pt2, const QgsPoint &pt3, double epsilon=1E8) 
Constructs the smallest circle from 3 points. More...  
Static Public Member Functions inherited from QgsEllipse  
static QgsEllipse  fromCenter2Points (const QgsPoint &ptc, const QgsPoint &pt1, const QgsPoint &pt2) 
Constructs an ellipse by a central point and two other points. More...  
static QgsEllipse  fromCenterPoint (const QgsPoint &ptc, const QgsPoint &pt1) 
Constructs an ellipse by a center point and a another point. More...  
static QgsEllipse  fromExtent (const QgsPoint &pt1, const QgsPoint &pt2) 
Constructs an ellipse by an extent (aka bounding box / QgsRectangle). More...  
static QgsEllipse  fromFoci (const QgsPoint &pt1, const QgsPoint &pt2, const QgsPoint &pt3) 
Constructs an ellipse by foci (pt1 and pt2) and a point pt3. More...  
Additional Inherited Members  
Protected Attributes inherited from QgsEllipse  
double  mAzimuth = 90.0 
QgsPoint  mCenter 
double  mSemiMajorAxis = 0.0 
double  mSemiMinorAxis = 0.0 
Circle geometry type.
A circle is defined by a center point with a radius and an azimuth. The azimuth is the north angle to the semimajor axis, in degrees. By default, the semimajor axis is oriented to the north (0 degrees).
Definition at line 43 of file qgscircle.h.
QgsCircle::QgsCircle  (  ) 
Definition at line 25 of file qgscircle.cpp.
QgsCircle::QgsCircle  (  const QgsPoint &  center, 
double  radius,  
double  azimuth = 0 

) 
Constructs a circle by defining all the members.
center  The center of the circle. 
radius  The radius of the circle. 
azimuth  Angle in degrees started from the North to the first quadrant. 
Definition at line 31 of file qgscircle.cpp.

overridevirtual 
The area of the ellipse.
Reimplemented from QgsEllipse.
Definition at line 294 of file qgscircle.cpp.

overridevirtual 
Returns the minimal bounding box for the ellipse.
Reimplemented from QgsEllipse.
Definition at line 355 of file qgscircle.cpp.
bool QgsCircle::contains  (  const QgsPoint &  point, 
double  epsilon = 1E8 

)  const 
Returns true
if the circle contains the point.
Definition at line 350 of file qgscircle.cpp.
Constructs a circle by 2 points on the circle.
The center point can have m value which is the result from the midpoint operation between pt1 and pt2. Z dimension is also supported and is retrieved from the first 3D point amongst pt1 and pt2. The radius is calculated from the 2D distance between pt1 and pt2. The azimuth is the angle between pt1 and pt2.
pt1  First point. 
pt2  Second point. 
Definition at line 37 of file qgscircle.cpp.

static 
Constructs a circle by 3 points on the circle.
M value is dropped for the center point. Z dimension is supported and is retrieved from the first 3D point amongst pt1, pt2 and pt3. The azimuth always takes the default value. If the points are colinear an empty circle is returned.
pt1  First point. 
pt2  Second point. 
pt3  Third point. 
epsilon  Value used to compare point. 
Definition at line 83 of file qgscircle.cpp.

static 
Constructs a circle by 3 tangents on the circle (aka inscribed circle of a triangle).
Z and m values are dropped for the center point. The azimuth always takes the default value.
pt1_tg1  First point of the first tangent. 
pt2_tg1  Second point of the first tangent. 
pt1_tg2  First point of the second tangent. 
pt2_tg2  Second point of the second tangent. 
pt1_tg3  First point of the third tangent. 
pt2_tg3  Second point of the third tangent. 
epsilon  Value used to compare point. 
Definition at line 191 of file qgscircle.cpp.

static 
Constructs a circle by a center point and a diameter.
The center point keeps z and m values from center.
center  Center point. 
diameter  Diameter of the circle. 
azimuth  Azimuth of the circle. 
Definition at line 176 of file qgscircle.cpp.
Constructs a circle by a center point and another point.
The center point keeps z and m values from center. Axes are calculated from the 2D distance between center and pt1. The azimuth is the angle between center and pt1.
center  Center point. 
pt1  A point on the circle. 
Definition at line 181 of file qgscircle.cpp.
Constructs a circle by an extent (aka bounding box / QgsRectangle).
The center point can have m value which is the result from the midpoint operation between pt1 and pt2. Z dimension is also supported and is retrieved from the first 3D point amongst pt1 and pt2. Axes are calculated from the 2D distance between pt1 and pt2. The azimuth always takes the default value.
pt1  First corner. 
pt2  Second corner. 
Definition at line 279 of file qgscircle.cpp.
int QgsCircle::innerTangents  (  const QgsCircle &  other, 
QgsPointXY &  line1P1,  
QgsPointXY &  line1P2,  
QgsPointXY &  line2P1,  
QgsPointXY &  line2P2  
)  const 
Calculates the inner tangent points between this circle and an other circle.
The inner tangent points correspond to the points at which the two lines which are drawn so that they are tangential to both circles but on different sides, touching the circles and 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).
Note that this method is 2D only and does not consider the zvalue of the circle.
Definition at line 273 of file qgscircle.cpp.
int QgsCircle::intersections  (  const QgsCircle &  other, 
QgsPoint &  intersection1,  
QgsPoint &  intersection2,  
bool  useZ = false 

)  const 
Calculates the intersections points between this circle and an other circle.
If found, the intersection points will be stored in intersection1 and intersection2.
By default this method does not consider any z values and instead treats the circles as 2dimensional. If useZ is set to true
, then an intersection will only occur if the z values of both circles are equal. In this case the points returned for intersection1 and intersection2 will contain the z value of the circle intersections.
Definition at line 239 of file qgscircle.cpp.

static 
Constructs the smallest circle from 3 points.
Z and m values are dropped for the center point. The azimuth always takes the default value. If the points are colinear an empty circle is returned.
pt1  First point. 
pt2  Second point. 
pt3  Third point. 
epsilon  Value used to compare point. 
Definition at line 223 of file qgscircle.cpp.
QVector< QgsPoint > QgsCircle::northQuadrant  (  )  const 
The four quadrants of the ellipse.
They are oriented and started from North.
Definition at line 316 of file qgscircle.cpp.
int QgsCircle::outerTangents  (  const QgsCircle &  other, 
QgsPointXY &  line1P1,  
QgsPointXY &  line1P2,  
QgsPointXY &  line2P1,  
QgsPointXY &  line2P2  
)  const 
Calculates the outer tangent points between this circle and an other circle.
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).
Note that this method is 2D only and does not consider the zvalue of the circle.
Definition at line 267 of file qgscircle.cpp.

overridevirtual 
The circumference of the ellipse using first approximation of Ramanujan.
Reimplemented from QgsEllipse.
Definition at line 299 of file qgscircle.cpp.

inline 
Returns the radius of the circle.
Definition at line 247 of file qgscircle.h.

inline 
Sets the radius of the circle.
Definition at line 249 of file qgscircle.h.

overridevirtual 
Inherited method.
Use setRadius instead.
Reimplemented from QgsEllipse.
Definition at line 304 of file qgscircle.cpp.

overridevirtual 
Inherited method.
Use setRadius instead.
Reimplemented from QgsEllipse.
Definition at line 310 of file qgscircle.cpp.
bool QgsCircle::tangentToPoint  (  const QgsPointXY &  p, 
QgsPointXY &  pt1,  
QgsPointXY &  pt2  
)  const 
Calculates the tangent points between this circle and the point p.
If found, the tangent points will be stored in pt1 and pt2.
Note that this method is 2D only and does not consider the zvalue of the circle.
true
if tangent was found.Definition at line 262 of file qgscircle.cpp.
QgsCircularString * QgsCircle::toCircularString  (  bool  oriented = false  )  const 
Returns a circular string from the circle.
oriented  If oriented is true the start point is from azimuth instead from north. 
Definition at line 327 of file qgscircle.cpp.

overridevirtual 
returns a string representation of the ellipse.
Members will be truncated to the specified precision.
Reimplemented from QgsEllipse.
Definition at line 360 of file qgscircle.cpp.