Base class for spline interpolations with C1 (first order parametric) continuity. More...

#include <qwt_spline.h>

Inheritance diagram for QwtSplineC1:

Public Member Functions
	QwtSplineC1 ()
	Constructor.

	~QwtSplineC1 () override
	Destructor.

virtual QPainterPath	painterPath (const QPolygonF &) const override
	Calculate an interpolated painter path.

virtual QVector< QLineF >	bezierControlLines (const QPolygonF &) const override
	Interpolate a curve with Bezier curves.

virtual QPolygonF	equidistantPolygon (const QPolygonF &, double distance, bool withNodes) const override
	Find an interpolated polygon with "equidistant" points.

virtual QVector< QwtSplinePolynomial >	polynomials (const QPolygonF &) const
	Calculate the interpolating polynomials for a non-parametric spline.

virtual QVector< double >	slopes (const QPolygonF &) const =0
	Find the first derivative at the control points.

virtual double	slopeAtBeginning (const QPolygonF &, double slopeNext) const
	Calculate the slope at the beginning of the spline.

virtual double	slopeAtEnd (const QPolygonF &, double slopeBefore) const
	Calculate the slope at the end of the spline.

Public Member Functions inherited from QwtSplineG1
	QwtSplineG1 ()
	Constructor.

	~QwtSplineG1 () override
	Destructor.

Public Member Functions inherited from QwtSplineInterpolating
	QwtSplineInterpolating ()
	Constructor.

	~QwtSplineInterpolating () override
	Destructor.

virtual QPolygonF	polygon (const QPolygonF &, double tolerance) const override
	Interpolate a curve by a polygon.

Public Member Functions inherited from QwtSpline
	QwtSpline ()
	Constructor.

virtual	~QwtSpline ()
	Destructor.

void	setParametrization (int type)
	Set parametrization by type.

void	setParametrization (QwtSplineParametrization *)
	Set parametrization object.

const QwtSplineParametrization *	parametrization () const
	Get parametrization.

void	setBoundaryType (BoundaryType)
	Set boundary type.

BoundaryType	boundaryType () const
	Get boundary type.

void	setBoundaryValue (BoundaryPosition, double value)
	Set boundary value.

double	boundaryValue (BoundaryPosition) const
	Get boundary value.

void	setBoundaryCondition (BoundaryPosition, int condition)
	Set boundary condition.

int	boundaryCondition (BoundaryPosition) const
	Get boundary condition.

void	setBoundaryConditions (int condition, double valueBegin=0.0, double valueEnd=0.0)
	Set boundary conditions for both ends.

virtual uint	locality () const
	Get locality (number of points used for calculation)

Additional Inherited Members
Public Types inherited from QwtSpline
enum	BoundaryType { ConditionalBoundaries , PeriodicPolygon , ClosedPolygon }
	Boundary type specifying the spline at its endpoints. More...

enum	BoundaryPosition { AtBeginning , AtEnd }
	position of a boundary condition More...

enum	BoundaryCondition { Clamped1 , Clamped2 , Clamped3 , LinearRunout }
	Boundary condition. More...

Detailed Description

Base class for spline interpolations with C1 (first order parametric) continuity.

All interpolations with C1 continuity are based on rules for finding the first derivative at some control points.

For non-parametric splines those points are the curve points, while for parametric splines the calculation is done twice using a parameter value t.

See also: QwtSplineParametrization

Constructor & Destructor Documentation

◆ QwtSplineC1()

QwtSplineC1::QwtSplineC1 ( )

Constructor.

The default setting is a non-closing spline with no parametrization (QwtSplineParametrization::ParameterX).

See also: QwtSpline::setParametrization(), QwtSpline::setBoundaryType()

Member Function Documentation

◆ bezierControlLines()

QVector< QLineF > QwtSplineC1::bezierControlLines ( const QPolygonF & points ) const

overridevirtual

Interpolate a curve with Bezier curves.

Interpolates a polygon piecewise with cubic Bezier curves and returns the 2 control points of each curve as QLineF.

Parameters

[in] points Control points

Returns: Control points of the interpolating Bezier curves

Implements QwtSplineInterpolating.

Reimplemented in QwtSplineC2, QwtSplineLocal, and QwtSplineCubic.

◆ equidistantPolygon()

QPolygonF QwtSplineC1::equidistantPolygon	(	const QPolygonF &	points,
		double	distance,
		bool	withNodes
	)		const

overridevirtual

Find an interpolated polygon with "equidistant" points.

The implementation is optimized for non-parametric curves (QwtSplineParametrization::ParameterX) and falls back to QwtSpline::equidistantPolygon() otherwise.

Parameters

[in]	points	Control nodes of the spline
[in]	distance	Distance between 2 points according to the parametrization
[in]	withNodes	When true, also add the control nodes (even if not being equidistant)

Returns: Interpolating polygon

See also: QwtSpline::equidistantPolygon()

Reimplemented from QwtSplineInterpolating.

Reimplemented in QwtSplineC2.

◆ painterPath()

QPainterPath QwtSplineC1::painterPath ( const QPolygonF & points ) const

overridevirtual

Calculate an interpolated painter path.

Interpolates a polygon piecewise into cubic Bezier curves and returns them as QPainterPath.

The implementation calculates the slopes at the control points and converts them into painter path elements in an additional loop.

Parameters

[in] points Control points

Returns: QPainterPath that can be rendered by QPainter

Note: Derived spline classes might overload painterPath() to avoid the extra loops for converting results into a QPainterPath

Reimplemented from QwtSplineInterpolating.

Reimplemented in QwtSplineC2, QwtSplineCubic, and QwtSplineLocal.

◆ polynomials()

QVector< QwtSplinePolynomial > QwtSplineC1::polynomials ( const QPolygonF & points ) const

virtual

Calculate the interpolating polynomials for a non-parametric spline.

C1 spline interpolations are based on finding values for the first derivatives at the control points. The interpolating polynomials can be calculated from the first derivatives using QwtSplinePolynomial::fromSlopes().

The default implementation is a two-pass calculation. In derived classes it might be overloaded by a one-pass implementation.

Parameters

[in] points Control points

Returns: Interpolating polynomials

Note: The x coordinates need to be increasing or decreasing

Reimplemented in QwtSplineC2, QwtSplineCubic, and QwtSplineLocal.

◆ slopeAtBeginning()

double QwtSplineC1::slopeAtBeginning	(	const QPolygonF &	points,
		double	slopeNext
	)		const

virtual

Calculate the slope at the beginning of the spline.

Parameters

[in]	points	Control points
[in]	slopeNext	Value of the first derivative at the second point

Returns: Value of the first derivative at the first point

See also: slopeAtEnd(), QwtSpline::boundaryCondition(), QwtSpline::boundaryValue()

◆ slopeAtEnd()

double QwtSplineC1::slopeAtEnd	(	const QPolygonF &	points,
		double	slopeBefore
	)		const

virtual

Calculate the slope at the end of the spline.

Parameters

[in]	points	Control points
[in]	slopeBefore	Value of the first derivative at the point before the last one

Returns: Value of the first derivative at the last point

See also: slopeAtBeginning(), QwtSpline::boundaryCondition(), QwtSpline::boundaryValue()

◆ slopes()

QVector< double > QwtSplineC1::slopes ( const QPolygonF & points ) const

pure virtual

Find the first derivative at the control points.

Parameters

points Control nodes of the spline

Returns: Vector with the values of the 2nd derivate at the control points

Note: The x coordinates need to be increasing or decreasing

Implemented in QwtSplineC2, QwtSplineCubic, and QwtSplineLocal.

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

/home/runner/work/QWT/QWT/src/plot/qwt_spline.h
/home/runner/work/QWT/QWT/src/plot/qwt_spline.cpp

Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ QwtSplineC1()

Member Function Documentation

◆ bezierControlLines()

◆ equidistantPolygon()

◆ painterPath()

◆ polynomials()

◆ slopeAtBeginning()

◆ slopeAtEnd()

◆ slopes()