Abstract base class for curved geometry type. More...

#include <qgscurve.h>

Inheritance diagram for QgsCurve:

[legend]

Public Types
enum	Orientation { Clockwise , CounterClockwise }
	Curve orientation. More...

Public Types inherited from QgsAbstractGeometry
enum	AxisOrder { XY = 0 , YX }
	Axis order for GML generation. More...

enum	SegmentationToleranceType { MaximumAngle = 0 , MaximumDifference }
	Segmentation tolerance as maximum angle or maximum difference between approximation and circle. More...

enum	WkbFlag { FlagExportTrianglesAsPolygons = 1 << 0 }
	WKB export flags. More...

Public Member Functions
	QgsCurve ()=default
	Constructor for QgsCurve. More...

virtual void	addToPainterPath (QPainterPath &path) const =0
	Adds a curve to a painter path. More...

void	adjacentVertices (QgsVertexId vertex, QgsVertexId &previousVertex, QgsVertexId &nextVertex) const override
	Returns the vertices adjacent to a specified vertex within a geometry. More...

QString	asKml (int precision=17) const override
	Returns a KML representation of the geometry. More...

QPainterPath	asQPainterPath () const override
	Returns the geometry represented as a QPainterPath. More...

virtual QPolygonF	asQPolygonF () const
	Returns a QPolygonF representing the points. More...

QgsAbstractGeometry *	boundary () const override
	Returns the closure of the combinatorial boundary of the geometry (ie the topological boundary of the geometry). More...

QgsRectangle	boundingBox () const override
	Returns the minimal bounding box for the geometry. More...

QgsCurve *	clone () const override=0
	Clones the geometry by performing a deep copy. More...

QgsCoordinateSequence	coordinateSequence () const override
	Retrieves the sequence of geometries, rings and nodes. More...

virtual QgsCurve *	curveSubstring (double startDistance, double endDistance) const =0
	Returns a new curve representing a substring of this curve. More...

virtual QgsLineString *	curveToLine (double tolerance=M_PI_2/90, SegmentationToleranceType toleranceType=MaximumAngle) const =0
	Returns a new line string geometry corresponding to a segmentized approximation of the curve. More...

virtual void	drawAsPolygon (QPainter &p) const =0
	Draws the curve as a polygon on the specified QPainter. More...

virtual QgsPoint	endPoint () const =0
	Returns the end point of the curve. More...

virtual bool	equals (const QgsCurve &other) const =0
	Checks whether this curve exactly equals another curve. More...

virtual QgsPoint *	interpolatePoint (double distance) const =0
	Returns an interpolated point on the curve at the specified distance. More...

virtual bool	isClosed () const SIP_HOLDGIL
	Returns `true` if the curve is closed. More...

virtual bool	isRing () const SIP_HOLDGIL
	Returns `true` if the curve is a ring. More...

bool	isValid (QString &error, int flags=0) const override
	Checks validity of the geometry, and returns `true` if the geometry is valid. More...

bool	nextVertex (QgsVertexId &id, QgsPoint &vertex) const override
	Returns next vertex id and coordinates. More...

virtual int	numPoints () const =0
	Returns the number of points in the curve. More...

bool	operator!= (const QgsAbstractGeometry &other) const override

bool	operator== (const QgsAbstractGeometry &other) const override

Orientation	orientation () const
	Returns the curve's orientation, e.g. More...

int	partCount () const override
	Returns count of parts contained in the geometry. More...

virtual bool	pointAt (int node, QgsPoint &point, QgsVertexId::VertexType &type) const =0
	Returns the point and vertex id of a point within the curve. More...

virtual void	points (QgsPointSequence &pt) const =0
	Returns a list of points within the curve. More...

virtual QgsCurve *	reversed () const =0
	Returns a reversed copy of the curve, where the direction of the curve has been flipped. More...

int	ringCount (int part=0) const override
	Returns the number of rings of which this geometry is built. More...

QgsCurve *	segmentize (double tolerance=M_PI_2/90, SegmentationToleranceType toleranceType=MaximumAngle) const override
	Returns a geometry without curves. More...

double	sinuosity () const
	Returns the curve sinuosity, which is the ratio of the curve length() to curve straightDistance2d(). More...

virtual QgsPoint	startPoint () const =0
	Returns the starting point of the curve. More...

double	straightDistance2d () const
	Returns the straight distance of the curve, i.e. More...

virtual void	sumUpArea (double &sum) const =0
	Sums up the area of the curve by iterating over the vertices (shoelace formula). More...

QgsCurve *	toCurveType () const override
	Returns the geometry converted to the more generic curve type. More...

QgsPoint	vertexAt (QgsVertexId id) const override
	Returns the point corresponding to a specified vertex id. More...

int	vertexCount (int part=0, int ring=0) const override
	Returns the number of vertices of which this geometry is built. More...

int	vertexNumberFromVertexId (QgsVertexId id) const override
	Returns the vertex number corresponding to a vertex id. More...

virtual double	xAt (int index) const =0
	Returns the x-coordinate of the specified node in the line string. More...

virtual double	yAt (int index) const =0
	Returns the y-coordinate of the specified node in the line string. More...

Public Member Functions inherited from QgsAbstractGeometry
	QgsAbstractGeometry ()=default
	Constructor for QgsAbstractGeometry. More...

	QgsAbstractGeometry (const QgsAbstractGeometry &geom)

virtual	~QgsAbstractGeometry ()=default

virtual bool	addMValue (double mValue=0)=0
	Adds a measure to the geometry, initialized to a preset value. More...

virtual bool	addZValue (double zValue=0)=0
	Adds a z-dimension to the geometry, initialized to a preset value. More...

virtual double	area () const
	Returns the planar, 2-dimensional area of the geometry. More...

virtual QDomElement	asGml2 (QDomDocument &doc, int precision=17, const QString &ns="gml", AxisOrder axisOrder=QgsAbstractGeometry::AxisOrder::XY) const =0
	Returns a GML2 representation of the geometry. More...

virtual QDomElement	asGml3 (QDomDocument &doc, int precision=17, const QString &ns="gml", AxisOrder axisOrder=QgsAbstractGeometry::AxisOrder::XY) const =0
	Returns a GML3 representation of the geometry. More...

QString	asJson (int precision=17)
	Returns a GeoJSON representation of the geometry as a QString. More...

virtual json	asJsonObject (int precision=17) const
	Returns a json object representation of the geometry. More...

virtual QByteArray	asWkb (WkbFlags flags=QgsAbstractGeometry::WkbFlags()) const =0
	Returns a WKB representation of the geometry. More...

virtual QString	asWkt (int precision=17) const =0
	Returns a WKT representation of the geometry. More...

virtual QgsPoint	centroid () const
	Returns the centroid of the geometry. More...

virtual void	clear ()=0
	Clears the geometry, ie reset it to a null geometry. More...

virtual double	closestSegment (const QgsPoint &pt, QgsPoint &segmentPt, QgsVertexId &vertexAfter, int leftOf=nullptr, double epsilon=4 std::numeric_limits< double >::epsilon()) const =0
	Searches for the closest segment of the geometry to a given point. More...

const_part_iterator	const_parts_begin () const
	Returns STL-style iterator pointing to the const first part of the geometry. More...

const_part_iterator	const_parts_end () const
	Returns STL-style iterator pointing to the imaginary const part after the last part of the geometry. More...

virtual bool	convertTo (QgsWkbTypes::Type type)
	Converts the geometry to a specified type. More...

virtual QgsAbstractGeometry *	createEmptyWithSameType () const =0
	Creates a new geometry with the same class and same WKB type as the original and transfers ownership. More...

virtual bool	deleteVertex (QgsVertexId position)=0
	Deletes a vertex within the geometry. More...

virtual int	dimension () const =0
	Returns the inherent dimension of the geometry. More...

virtual void	draw (QPainter &p) const =0
	Draws the geometry using the specified QPainter. More...

virtual bool	dropMValue ()=0
	Drops any measure values which exist in the geometry. More...

virtual bool	dropZValue ()=0
	Drops any z-dimensions which exist in the geometry. More...

virtual void	filterVertices (const std::function< bool(const QgsPoint &) > &filter)
	Filters the vertices from the geometry in place, removing any which do not return `true` for the filter function check. More...

virtual bool	fromWkb (QgsConstWkbPtr &wkb)=0
	Sets the geometry from a WKB string. More...

virtual bool	fromWkt (const QString &wkt)=0
	Sets the geometry from a WKT string. More...

virtual QString	geometryType () const =0
	Returns a unique string representing the geometry type. More...

virtual bool	hasCurvedSegments () const
	Returns `true` if the geometry contains curved segments. More...

virtual bool	insertVertex (QgsVertexId position, const QgsPoint &vertex)=0
	Inserts a vertex into the geometry. More...

bool	is3D () const SIP_HOLDGIL
	Returns `true` if the geometry is 3D and contains a z-value. More...

virtual bool	isEmpty () const
	Returns `true` if the geometry is empty. More...

bool	isMeasure () const SIP_HOLDGIL
	Returns `true` if the geometry contains m values. More...

virtual double	length () const
	Returns the planar, 2-dimensional length of the geometry. More...

virtual bool	moveVertex (QgsVertexId position, const QgsPoint &newPos)=0
	Moves a vertex within the geometry. More...

virtual int	nCoordinates () const
	Returns the number of nodes contained in the geometry. More...

QgsAbstractGeometry &	operator= (const QgsAbstractGeometry &geom)

QgsGeometryPartIterator	parts ()
	Returns Java-style iterator for traversal of parts of the geometry. More...

QgsGeometryConstPartIterator	parts () const
	Returns Java-style iterator for traversal of parts of the geometry. More...

part_iterator	parts_begin ()
	Returns STL-style iterator pointing to the first part of the geometry. More...

part_iterator	parts_end ()
	Returns STL-style iterator pointing to the imaginary part after the last part of the geometry. More...

virtual double	perimeter () const
	Returns the planar, 2-dimensional perimeter of the geometry. More...

virtual bool	removeDuplicateNodes (double epsilon=4 *std::numeric_limits< double >::epsilon(), bool useZValues=false)=0
	Removes duplicate nodes from the geometry, wherever removing the nodes does not result in a degenerate geometry. More...

virtual double	segmentLength (QgsVertexId startVertex) const =0
	Returns the length of the segment of the geometry which begins at startVertex. More...

virtual QgsAbstractGeometry *	snappedToGrid (double hSpacing, double vSpacing, double dSpacing=0, double mSpacing=0) const =0
	Makes a new geometry with all the points or vertices snapped to the closest point of the grid. More...

virtual void	swapXy ()=0
	Swaps the x and y coordinates from the geometry. More...

virtual void	transform (const QgsCoordinateTransform &ct, QgsCoordinateTransform::TransformDirection d=QgsCoordinateTransform::ForwardTransform, bool transformZ=false) SIP_THROW(QgsCsException)=0
	Transforms the geometry using a coordinate transform. More...

virtual void	transform (const QTransform &t, double zTranslate=0.0, double zScale=1.0, double mTranslate=0.0, double mScale=1.0)=0
	Transforms the x and y components of the geometry using a QTransform object t. More...

virtual bool	transform (QgsAbstractGeometryTransformer transformer, QgsFeedback feedback=nullptr)=0
	Transforms the vertices from the geometry in place, using the specified geometry transformer object. More...

virtual void	transformVertices (const std::function< QgsPoint(const QgsPoint &) > &transform)
	Transforms the vertices from the geometry in place, applying the transform function to every vertex. More...

virtual double	vertexAngle (QgsVertexId vertex) const =0
	Returns approximate angle at a vertex. More...

QgsVertexIterator	vertices () const
	Returns a read-only, Java-style iterator for traversal of vertices of all the geometry, including all geometry parts and rings. More...

vertex_iterator	vertices_begin () const
	Returns STL-style iterator pointing to the first vertex of the geometry. More...

vertex_iterator	vertices_end () const
	Returns STL-style iterator pointing to the imaginary vertex after the last vertex of the geometry. More...

virtual int	wkbSize (QgsAbstractGeometry::WkbFlags flags=QgsAbstractGeometry::WkbFlags()) const =0
	Returns the length of the QByteArray returned by asWkb() More...

QgsWkbTypes::Type	wkbType () const SIP_HOLDGIL
	Returns the WKB type of the geometry. More...

QString	wktTypeStr () const
	Returns the WKT type string of the geometry. More...

Static Public Member Functions
static const QgsCurve *	cast (const QgsAbstractGeometry *geom)
	Cast the geom to a QgsCurve. More...

Protected Member Functions
int	childCount () const override
	Returns number of child geometries (for geometries with child geometries) or child points (for geometries without child geometries - i.e. More...

QgsPoint	childPoint (int index) const override
	Returns point at index (for geometries without child geometries - i.e. More...

void	clearCache () const override
	Clears any cached parameters associated with the geometry, e.g., bounding boxes. More...

bool	snapToGridPrivate (double hSpacing, double vSpacing, double dSpacing, double mSpacing, const QVector< double > &srcX, const QVector< double > &srcY, const QVector< double > &srcZ, const QVector< double > &srcM, QVector< double > &outX, QVector< double > &outY, QVector< double > &outZ, QVector< double > &outM) const
	Helper function for QgsCurve subclasses to snap to grids. More...

Protected Member Functions inherited from QgsAbstractGeometry
virtual QgsRectangle	calculateBoundingBox () const
	Default calculator for the minimal bounding box for the geometry. More...

virtual QgsAbstractGeometry *	childGeometry (int index) const
	Returns pointer to child geometry (for geometries with child geometries - i.e. More...

virtual bool	hasChildGeometries () const
	Returns whether the geometry has any child geometries (`false` for point / curve, `true` otherwise) More...

void	setZMTypeFromSubGeometry (const QgsAbstractGeometry *subggeom, QgsWkbTypes::Type baseGeomType)
	Updates the geometry type based on whether sub geometries contain z or m values. More...

Additional Inherited Members
Protected Attributes inherited from QgsAbstractGeometry
QgsWkbTypes::Type	mWkbType = QgsWkbTypes::Unknown

Detailed Description

Abstract base class for curved geometry type.

Since: QGIS 2.10

Definition at line 35 of file qgscurve.h.

Member Enumeration Documentation

◆ Orientation

enum QgsCurve::Orientation

Curve orientation.

Enumerator
Clockwise	Clockwise orientation.
CounterClockwise	Counter-clockwise orientation.

Definition at line 238 of file qgscurve.h.

Constructor & Destructor Documentation

◆ QgsCurve()

QgsCurve::QgsCurve ( )

default

Constructor for QgsCurve.

Member Function Documentation

◆ addToPainterPath()

virtual void QgsCurve::addToPainterPath ( QPainterPath & path ) const

pure virtual

Adds a curve to a painter path.

Implemented in QgsLineString, QgsCompoundCurve, and QgsCircularString.

◆ adjacentVertices()

void QgsCurve::adjacentVertices	(	QgsVertexId	vertex,
		QgsVertexId &	previousVertex,
		QgsVertexId &	nextVertex
	)		const

overridevirtual

Returns the vertices adjacent to a specified vertex within a geometry.

Since: QGIS 3.0

Implements QgsAbstractGeometry.

Definition at line 103 of file qgscurve.cpp.

◆ asKml()

QString QgsCurve::asKml ( int precision = 17 ) const

overridevirtual

Returns a KML representation of the geometry.

Since: QGIS 3.12

Implements QgsAbstractGeometry.

Reimplemented in QgsLineString.

Definition at line 155 of file qgscurve.cpp.

◆ asQPainterPath()

QPainterPath QgsCurve::asQPainterPath ( ) const

overridevirtual

Returns the geometry represented as a QPainterPath.

Warning: not all geometry subclasses can be represented by a QPainterPath, e.g. points and multipoint geometries will return an empty path.

Since: QGIS 3.16

Implements QgsAbstractGeometry.

Definition at line 61 of file qgscurve.cpp.

◆ asQPolygonF()

QPolygonF QgsCurve::asQPolygonF ( ) const

virtual

Returns a QPolygonF representing the points.

Reimplemented in QgsLineString.

Definition at line 230 of file qgscurve.cpp.

◆ boundary()

QgsAbstractGeometry * QgsCurve::boundary ( ) const

overridevirtual

Returns the closure of the combinatorial boundary of the geometry (ie the topological boundary of the geometry).

For instance, a polygon geometry will have a boundary consisting of the linestrings for each ring in the polygon.

Returns: boundary for geometry. May be nullptr for some geometry types.

Since: QGIS 3.0

Implements QgsAbstractGeometry.

Definition at line 140 of file qgscurve.cpp.

◆ boundingBox()

QgsRectangle QgsCurve::boundingBox ( ) const

overridevirtual

Returns the minimal bounding box for the geometry.

Implements QgsAbstractGeometry.

Definition at line 202 of file qgscurve.cpp.

◆ cast()

static const QgsCurve* QgsCurve::cast ( const QgsAbstractGeometry * geom )

inlinestatic

Cast the geom to a QgsCurve.

Should be used by qgsgeometry_cast<QgsCurve *>( geometry ).

Note: Not available in Python. Objects will be automatically be converted to the appropriate target type.

Since: QGIS 3.0

Definition at line 262 of file qgscurve.h.

◆ childCount()

int QgsCurve::childCount ( ) const

overrideprotectedvirtual

Returns number of child geometries (for geometries with child geometries) or child points (for geometries without child geometries - i.e.

curve / point)

Note: used for vertex_iterator implementation

Since: QGIS 3.0

Reimplemented from QgsAbstractGeometry.

Definition at line 265 of file qgscurve.cpp.

◆ childPoint()

QgsPoint QgsCurve::childPoint ( int index ) const

overrideprotectedvirtual

Returns point at index (for geometries without child geometries - i.e.

curve / point)

Note: used for vertex_iterator implementation

Since: QGIS 3.0

Reimplemented from QgsAbstractGeometry.

Definition at line 270 of file qgscurve.cpp.

◆ clearCache()

void QgsCurve::clearCache ( ) const

overrideprotectedvirtual

Clears any cached parameters associated with the geometry, e.g., bounding boxes.

Reimplemented from QgsAbstractGeometry.

Definition at line 257 of file qgscurve.cpp.

◆ clone()

QgsCurve* QgsCurve::clone ( ) const

overridepure virtual

Clones the geometry by performing a deep copy.

Implements QgsAbstractGeometry.

Implemented in QgsLineString, QgsCompoundCurve, and QgsCircularString.

◆ coordinateSequence()

QgsCoordinateSequence QgsCurve::coordinateSequence ( ) const

overridevirtual

Retrieves the sequence of geometries, rings and nodes.

Returns: coordinate sequence

Implements QgsAbstractGeometry.

Definition at line 68 of file qgscurve.cpp.

◆ curveSubstring()

virtual QgsCurve* QgsCurve::curveSubstring	(	double	startDistance,
		double	endDistance
	)		const

pure virtual

Returns a new curve representing a substring of this curve.

The startDistance and endDistance arguments specify the length along the curve which the substring should start and end at. If the endDistance is greater than the total length of the curve then any "extra" length will be ignored.

If z or m values are present, the output z and m will be interpolated using the existing vertices' z or m values.

Since: QGIS 3.4

Implemented in QgsLineString, QgsCompoundCurve, and QgsCircularString.

◆ curveToLine()

virtual QgsLineString* QgsCurve::curveToLine	(	double	tolerance = `M_PI_2/90`,
		SegmentationToleranceType	toleranceType = `MaximumAngle`
	)		const

pure virtual

Returns a new line string geometry corresponding to a segmentized approximation of the curve.

Parameters

tolerance	segmentation tolerance
toleranceType	maximum segmentation angle or maximum difference between approximation and curve

Uses a MaximumAngle tolerance of 1 degrees by default (360 segments in a full circle)

Implemented in QgsLineString, QgsCompoundCurve, and QgsCircularString.

◆ drawAsPolygon()

virtual void QgsCurve::drawAsPolygon ( QPainter & p ) const

pure virtual

Draws the curve as a polygon on the specified QPainter.

Parameters

p	destination QPainter

Implemented in QgsLineString, QgsCompoundCurve, and QgsCircularString.

◆ endPoint()

virtual QgsPoint QgsCurve::endPoint ( ) const

pure virtual

Returns the end point of the curve.

See also: startPoint

Implemented in QgsLineString, QgsCompoundCurve, and QgsCircularString.

◆ equals()

virtual bool QgsCurve::equals ( const QgsCurve & other ) const

pure virtual

Checks whether this curve exactly equals another curve.

Since: QGIS 3.0

Implemented in QgsLineString, QgsCompoundCurve, and QgsCircularString.

◆ interpolatePoint()

virtual QgsPoint* QgsCurve::interpolatePoint ( double distance ) const

pure virtual

Returns an interpolated point on the curve at the specified distance.

If z or m values are present, the output z and m will be interpolated using the existing vertices' z or m values.

If distance is negative, or is greater than the length of the curve, nullptr will be returned.

Since: QGIS 3.4

Implemented in QgsLineString, QgsCompoundCurve, and QgsCircularString.

◆ isClosed()

bool QgsCurve::isClosed ( ) const

virtual

Returns true if the curve is closed.

Definition at line 40 of file qgscurve.cpp.

◆ isRing()

bool QgsCurve::isRing ( ) const

virtual

Returns true if the curve is a ring.

Definition at line 56 of file qgscurve.cpp.

◆ isValid()

bool QgsCurve::isValid	(	QString &	error,
		int	flags = `0`
	)		const

overridevirtual

Checks validity of the geometry, and returns true if the geometry is valid.

Parameters

error	will be set to the validity error message
flags	indicates optional flags which control the type of validity checking performed (corresponding to QgsGeometry::ValidityFlags).

Returns: true if geometry is valid

Since: QGIS 3.8

Implements QgsAbstractGeometry.

Reimplemented in QgsLineString.

Definition at line 211 of file qgscurve.cpp.

◆ nextVertex()

bool QgsCurve::nextVertex	(	QgsVertexId &	id,
		QgsPoint &	vertex
	)		const

overridevirtual

Returns next vertex id and coordinates.

Parameters

id	initial value should be the starting vertex id. The next vertex id will be stored in this variable if found.
vertex	container for found node

Returns: false if at end

Implements QgsAbstractGeometry.

Definition at line 78 of file qgscurve.cpp.

◆ numPoints()

virtual int QgsCurve::numPoints ( ) const

pure virtual

Returns the number of points in the curve.

Implemented in QgsLineString, QgsCompoundCurve, and QgsCircularString.

◆ operator!=()

bool QgsCurve::operator!= ( const QgsAbstractGeometry & other ) const

overridevirtual

Implements QgsAbstractGeometry.

Definition at line 35 of file qgscurve.cpp.

◆ operator==()

bool QgsCurve::operator== ( const QgsAbstractGeometry & other ) const

overridevirtual

Implements QgsAbstractGeometry.

Definition at line 26 of file qgscurve.cpp.

◆ orientation()

QgsCurve::Orientation QgsCurve::orientation ( ) const

Returns the curve's orientation, e.g.

clockwise or counter-clockwise.

Warning: The result is not predictable for non-closed curves.

Since: QGIS 3.6

Definition at line 250 of file qgscurve.cpp.

◆ partCount()

int QgsCurve::partCount ( ) const

overridevirtual

Returns count of parts contained in the geometry.

See also: vertexCount; ringCount

Implements QgsAbstractGeometry.

Definition at line 184 of file qgscurve.cpp.

◆ pointAt()

virtual bool QgsCurve::pointAt	(	int	node,
		QgsPoint &	point,
		QgsVertexId::VertexType &	type
	)		const

pure virtual

Returns the point and vertex id of a point within the curve.

Parameters

node	node number, where the first node is 0
point	will be set to point at corresponding node in the curve
type	will be set to the vertex type of the node

Returns: true if node exists within the curve

Implemented in QgsLineString, QgsCompoundCurve, and QgsCircularString.

◆ points()

virtual void QgsCurve::points ( QgsPointSequence & pt ) const

pure virtual

Returns a list of points within the curve.

Implemented in QgsCompoundCurve, QgsCircularString, and QgsLineString.

◆ reversed()

virtual QgsCurve* QgsCurve::reversed ( ) const

pure virtual

Returns a reversed copy of the curve, where the direction of the curve has been flipped.

Since: QGIS 2.14

Implemented in QgsLineString, QgsCompoundCurve, and QgsCircularString.

◆ ringCount()

int QgsCurve::ringCount ( int part = 0 ) const

overridevirtual

Returns the number of rings of which this geometry is built.

Implements QgsAbstractGeometry.

Definition at line 178 of file qgscurve.cpp.

◆ segmentize()

QgsCurve * QgsCurve::segmentize	(	double	tolerance = `M_PI_2 / 90`,
		SegmentationToleranceType	toleranceType = `MaximumAngle`
	)		const

overridevirtual

Returns a geometry without curves.

Caller takes ownership

Parameters

tolerance	segmentation tolerance
toleranceType	maximum segmentation angle or maximum difference between approximation and curve

Reimplemented from QgsAbstractGeometry.

Definition at line 166 of file qgscurve.cpp.

◆ sinuosity()

double QgsCurve::sinuosity ( ) const

Returns the curve sinuosity, which is the ratio of the curve length() to curve straightDistance2d().

Larger numbers indicate a more "sinuous" curve (i.e. more "bendy"). The minimum value returned of 1.0 indicates a perfectly straight curve.

If a curve isClosed(), it has infinite sinuosity and will return NaN.

Since: QGIS 3.2

Definition at line 241 of file qgscurve.cpp.

◆ snapToGridPrivate()

bool QgsCurve::snapToGridPrivate	(	double	hSpacing,
		double	vSpacing,
		double	dSpacing,
		double	mSpacing,
		const QVector< double > &	srcX,
		const QVector< double > &	srcY,
		const QVector< double > &	srcZ,
		const QVector< double > &	srcM,
		QVector< double > &	outX,
		QVector< double > &	outY,
		QVector< double > &	outZ,
		QVector< double > &	outM
	)		const

protected

Helper function for QgsCurve subclasses to snap to grids.

Note: Not available in Python bindings.

Definition at line 280 of file qgscurve.cpp.

◆ startPoint()

virtual QgsPoint QgsCurve::startPoint ( ) const

pure virtual

Returns the starting point of the curve.

See also: endPoint

Implemented in QgsLineString, QgsCompoundCurve, and QgsCircularString.

◆ straightDistance2d()

double QgsCurve::straightDistance2d ( ) const

Returns the straight distance of the curve, i.e.

the direct/euclidean distance between the first and last vertex of the curve. (Also known as "as the crow flies" distance).

Since: QGIS 3.2

Definition at line 236 of file qgscurve.cpp.

◆ sumUpArea()

virtual void QgsCurve::sumUpArea ( double & sum ) const

pure virtual

Sums up the area of the curve by iterating over the vertices (shoelace formula).

Implemented in QgsLineString, QgsCompoundCurve, and QgsCircularString.

◆ toCurveType()

QgsCurve * QgsCurve::toCurveType ( ) const

overridevirtual

Returns the geometry converted to the more generic curve type.

E.g. QgsLineString -> QgsCompoundCurve, QgsPolygon -> QgsCurvePolygon, QgsMultiLineString -> QgsMultiCurve, QgsMultiPolygon -> QgsMultiSurface

Returns: the converted geometry. Caller takes ownership

Implements QgsAbstractGeometry.

Reimplemented in QgsLineString.

Definition at line 197 of file qgscurve.cpp.

◆ vertexAt()

QgsPoint QgsCurve::vertexAt ( QgsVertexId id ) const

overridevirtual

Returns the point corresponding to a specified vertex id.

Implements QgsAbstractGeometry.

Definition at line 189 of file qgscurve.cpp.

◆ vertexCount()

int QgsCurve::vertexCount	(	int	part = `0`,
		int	ring = `0`
	)		const

overridevirtual

Returns the number of vertices of which this geometry is built.

Implements QgsAbstractGeometry.

Definition at line 171 of file qgscurve.cpp.

◆ vertexNumberFromVertexId()

int QgsCurve::vertexNumberFromVertexId ( QgsVertexId id ) const

overridevirtual

Returns the vertex number corresponding to a vertex id.

The vertex numbers start at 0, so a return value of 0 corresponds to the first vertex.

Returns -1 if a corresponding vertex could not be found.

Since: QGIS 3.0

Implements QgsAbstractGeometry.

Definition at line 131 of file qgscurve.cpp.

◆ xAt()

virtual double QgsCurve::xAt ( int index ) const

pure virtual

Returns the x-coordinate of the specified node in the line string.

Parameters

index index of node, where the first node in the line is 0

Returns: x-coordinate of node, or 0.0 if index is out of bounds

Implemented in QgsCompoundCurve, QgsCircularString, and QgsLineString.

◆ yAt()

virtual double QgsCurve::yAt ( int index ) const

pure virtual

Returns the y-coordinate of the specified node in the line string.

Parameters

index index of node, where the first node in the line is 0

Returns: y-coordinate of node, or 0.0 if index is out of bounds

Implemented in QgsCompoundCurve, QgsCircularString, and QgsLineString.

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

/build/qgis-3.18.1+99unstable/src/core/geometry/qgscurve.h
/build/qgis-3.18.1+99unstable/src/core/geometry/qgscurve.cpp

Public Types

Public Member Functions

Static Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

◆ Orientation

Constructor & Destructor Documentation

◆ QgsCurve()

Member Function Documentation

◆ addToPainterPath()

◆ adjacentVertices()

◆ asKml()

◆ asQPainterPath()

◆ asQPolygonF()

◆ boundary()

◆ boundingBox()

◆ cast()

◆ childCount()

◆ childPoint()

◆ clearCache()

◆ clone()

◆ coordinateSequence()

◆ curveSubstring()

◆ curveToLine()

◆ drawAsPolygon()

◆ endPoint()

◆ equals()

◆ interpolatePoint()

◆ isClosed()

◆ isRing()

◆ isValid()

◆ nextVertex()

◆ numPoints()

◆ operator!=()

◆ operator==()

◆ orientation()

◆ partCount()

◆ pointAt()

◆ points()

◆ reversed()

◆ ringCount()

◆ segmentize()

◆ sinuosity()

◆ snapToGridPrivate()

◆ startPoint()

◆ straightDistance2d()

◆ sumUpArea()

◆ toCurveType()

◆ vertexAt()

◆ vertexCount()

◆ vertexNumberFromVertexId()

◆ xAt()

◆ yAt()