Base class for a spline interpolation. More...

#include <qwt_spline.h>

Inheritance diagram for QwtSplineInterpolating:

Public Member Functions
	QwtSplineInterpolating ()
	Constructor.

virtual	~QwtSplineInterpolating ()
	Destructor.

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

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

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

virtual QVector< QLineF >	bezierControlLines (const QPolygonF &) const =0
	Interpolate a curve with Bezier curves.

Public Member Functions inherited from QwtSpline
	QwtSpline ()
	Constructor.

virtual	~QwtSpline ()
	Destructor.

void	setParametrization (int type)
	Define the parametrization for a parametric spline approximation The default setting is a chordal parametrization.

void	setParametrization (QwtSplineParametrization *)
	Define the parametrization for a parametric spline approximation The default setting is a chordal parametrization.

const QwtSplineParametrization *	parametrization () const

void	setBoundaryType (BoundaryType)
	Define the boundary type for the endpoints of the approximating spline.

BoundaryType	boundaryType () const

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

double	boundaryValue (BoundaryPosition) const

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

int	boundaryCondition (BoundaryPosition) const

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

virtual uint	locality () const
	The locality of an spline interpolation identifies how many adjacent polynomials are affected, when changing the position of one point.

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 a spline interpolation.

Spline interpolation is the process of interpolating a set of points piecewise with polynomials. The initial set of points is preserved.

Member Function Documentation

◆ bezierControlLines()

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

pure 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

Implemented in QwtSplineC1, QwtSplineC2, QwtSplineLocal, QwtSplinePleasing, and QwtSplineCubic.

◆ equidistantPolygon()

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

virtual

Find an interpolated polygon with "equidistant" points.

When withNodes is disabled all points of the resulting polygon will be equidistant according to the parametrization.

When withNodes is enabled the resulting polygon will also include the control points and the interpolated points are always aligned to the control point before ( points[i] + i * distance ).

The implementation calculates bezier curves first and calculates the interpolated points in a second run.

Parameters

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

Returns: Interpolating polygon

See also: bezierControlLines()

Reimplemented in QwtSplineC1, and QwtSplineC2.

◆ painterPath()

QPainterPath QwtSplineInterpolating::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.

The implementation calculates the Bezier control lines first and converts them into painter path elements in an additional loop.

Parameters

points Control points

Returns: Painter path, that can be rendered by QPainter

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

See also: bezierControlLines()

Implements QwtSpline.

Reimplemented in QwtSplineC1, QwtSplineC2, QwtSplineCubic, QwtSplineLocal, and QwtSplinePleasing.

◆ polygon()

QPolygonF QwtSplineInterpolating::polygon	(	const QPolygonF &	points,
		double	tolerance
	)		const

virtual

Interpolate a curve by a polygon.

Interpolates a polygon piecewise with Bezier curves approximating them by polygons.

The approximation is based on "Piecewise Linear Approximation of Bézier Curves" by Roger Willcocks ( http://www.rops.org )

Parameters

points	Control points
tolerance	Maximum for the accepted error of the approximation

Returns: polygon approximating the interpolating polynomials

See also: bezierControlLines(), QwtSplineBezier::toPolygon()

Reimplemented from QwtSpline.

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

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

Public Member Functions

Additional Inherited Members

Detailed Description

Member Function Documentation

◆ bezierControlLines()

◆ equidistantPolygon()

◆ painterPath()

◆ polygon()