Base class for spline interpolation. More...

#include <qwt_spline.h>

Inheritance diagram for QwtSplineInterpolating:

Public Member Functions
	QwtSplineInterpolating ()
	Constructor.

	~QwtSplineInterpolating () override
	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 override
	Interpolate a curve by a polygon.

virtual QPainterPath	painterPath (const QPolygonF &) const 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)
	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 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

[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: bezierControlLines()

Reimplemented in QwtSplineC1, and QwtSplineC2.

◆ painterPath()

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

overridevirtual

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

[in] 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

overridevirtual

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 Bezier Curves" by Roger Willcocks ( http://www.rops.org )

Parameters

[in]	points	Control points
[in]	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/plot/qwt_spline.h
/home/runner/work/QWT/QWT/src/plot/qwt_spline.cpp

Public Member Functions

Additional Inherited Members

Detailed Description

Member Function Documentation

◆ bezierControlLines()

◆ equidistantPolygon()

◆ painterPath()

◆ polygon()