A spline with C1 continuity. More...

#include <qwt_spline_local.h>

Inheritance diagram for QwtSplineLocal:

Public Types
enum	Type { Cardinal, ParabolicBlending, Akima, PChip }
	Spline interpolation type. More...
Public Member Functions
virtual QVector< QLineF >	bezierControlLines (const QPolygonF &) const
	Interpolate a curve with Bezier curves.
virtual uint	locality () const
virtual QPainterPath	painterPath (const QPolygonF &) const
	Interpolate a curve with Bezier curves.
virtual QVector < QwtSplinePolynomial >	polynomials (const QPolygonF &) const
	Calculate the interpolating polynomials for a non parametric spline.
	QwtSplineLocal (Type type)
	Constructor.
virtual QVector< double >	slopes (const QPolygonF &) const
	Find the first derivative at the control points.
Type	type () const
virtual	~QwtSplineLocal ()
	Destructor.
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