A spline with C1 continuity. More...

#include <qwt_spline_local.h>

Inheritance diagram for QwtSplineLocal:

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Public Types
enum	Type { Cardinal, ParabolicBlending, Akima, PChip }
	Spline interpolation type. More...

Public Types inherited from QwtSpline
enum	BoundaryCondition { Clamped1, Clamped2, Clamped3, LinearRunout }
	Boundary condition. More...

enum	BoundaryPosition { AtBeginning, AtEnd }

enum	BoundaryType { ConditionalBoundaries, PeriodicPolygon, ClosedPolygon }

Public Member Functions
virtual QVector< QLineF >	bezierControlLines (const QPolygonF &) const
	Interpolate a curve with Bezier curves. More...

virtual uint	locality () const

virtual QPainterPath	painterPath (const QPolygonF &) const
	Interpolate a curve with Bezier curves. More...

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

	QwtSplineLocal (Type type)
	Constructor. More...

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

Type	type () const

virtual	~QwtSplineLocal ()
	Destructor. More...

Public Member Functions inherited from QwtSplineC1
virtual QPolygonF	equidistantPolygon (const QPolygonF &, double distance, bool withNodes) const
	Find an interpolated polygon with "equidistant" points. More...

	QwtSplineC1 ()
	Constructor. More...

virtual double	slopeAtBeginning (const QPolygonF &, double slopeNext) const

virtual double	slopeAtEnd (const QPolygonF &, double slopeBefore) const

virtual	~QwtSplineC1 ()
	Destructor. More...

Public Member Functions inherited from QwtSplineG1
	QwtSplineG1 ()
	Constructor. More...

virtual	~QwtSplineG1 ()
	Destructor. More...

Public Member Functions inherited from QwtSplineInterpolating
virtual QPolygonF	polygon (const QPolygonF &, double tolerance) const
	Interpolate a curve by a polygon. More...

	QwtSplineInterpolating ()
	Constructor. More...

virtual	~QwtSplineInterpolating ()
	Destructor. More...

Public Member Functions inherited from QwtSpline
int	boundaryCondition (BoundaryPosition) const

BoundaryType	boundaryType () const

double	boundaryValue (BoundaryPosition) const

const QwtSplineParametrization *	parametrization () const

	QwtSpline ()
	Constructor. More...

void	setBoundaryCondition (BoundaryPosition, int condition)
	Define the condition for an endpoint of the spline. More...

void	setBoundaryConditions (int condition, double valueBegin=0.0, double valueEnd=0.0)
	Define the condition at the endpoints of a spline. More...

void	setBoundaryType (BoundaryType)

void	setBoundaryValue (BoundaryPosition, double value)
	Define the boundary value. More...

void	setParametrization (int type)

void	setParametrization (QwtSplineParametrization *)

virtual	~QwtSpline ()
	Destructor. More...

Private Attributes
const Type	d_type

Detailed Description

A spline with C1 continuity.

QwtSplineLocal offers several standard algorithms for interpolating a curve with polynomials having C1 continuity at the control points. All algorithms are local in a sense, that changing one control point only few polynomials.

Definition at line 24 of file qwt_spline_local.h.

Member Enumeration Documentation

enum QwtSplineLocal::Type

Spline interpolation type.

All type of spline interpolations are lightweight algorithms calculating the slopes at a point by looking 1 or 2 points back and ahead.

Enumerator
Cardinal	A cardinal spline The cardinal spline interpolation is a very cheap calculation with a locality of 1.
ParabolicBlending	Parabolic blending is a cheap calculation with a locality of 1. Sometimes it is also called Cubic Bessel interpolation.
Akima	The algorithm of H.Akima is a calculation with a locality of 2.
PChip	Piecewise Cubic Hermite Interpolating Polynomial (PCHIP) is an algorithm that is popular because of being offered by MATLAB. It preserves the shape of the data and respects monotonicity. It has a locality of 1.

Definition at line 34 of file qwt_spline_local.h.

Constructor & Destructor Documentation

QwtSplineLocal::QwtSplineLocal ( Type type )

Constructor.

Parameters

type	Spline type, specifying the type of interpolation

See also: type()

Definition at line 448 of file qwt_spline_local.cpp.

QwtSplineLocal::~QwtSplineLocal ( )

virtual

Destructor.

Definition at line 459 of file qwt_spline_local.cpp.

Member Function Documentation

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

virtual

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

points Control points

Returns: Control points of the interpolating Bezier curves

Reimplemented from QwtSplineC1.

Definition at line 500 of file qwt_spline_local.cpp.

uint QwtSplineLocal::locality ( ) const

virtual

The locality of an spline interpolation identifies how many adjacent polynoms are affected, when changing the position of one point.

The Cardinal, ParabolicBlending and PChip algorithms have a locality of 1, while the Akima interpolation has a locality of 2.

Returns: 1 or 2.

Reimplemented from QwtSpline.

Definition at line 550 of file qwt_spline_local.cpp.

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

virtual

Interpolate a curve with Bezier curves.

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

Parameters

points Control points

Returns: Painter path, that can be rendered by QPainter

Reimplemented from QwtSplineC1.

Definition at line 480 of file qwt_spline_local.cpp.

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

virtual

Calculate the interpolating polynomials for a non parametric spline.

Parameters

points Control points

Returns: Interpolating polynomials

Note: The x coordinates need to be increasing or decreasing; The implementation simply calls QwtSplineC1::polynomials(), but is intended to be replaced by a one pass calculation some day.

Reimplemented from QwtSplineC1.

Definition at line 535 of file qwt_spline_local.cpp.

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

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

Implements QwtSplineC1.

Definition at line 519 of file qwt_spline_local.cpp.

QwtSplineLocal::Type QwtSplineLocal::type ( ) const

Returns: Spline type, specifying the type of interpolation

Definition at line 466 of file qwt_spline_local.cpp.

Member Data Documentation

const Type QwtSplineLocal::d_type

private

Definition at line 80 of file qwt_spline_local.h.

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

Public Types

Public Member Functions

Private Attributes

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation