QwtSplineParametrization类 参考

Curve parametrization used for a spline interpolation 更多...

#include <qwt_spline_parametrization.h>

Public 类型
enum	Type {   ParameterX , ParameterY , ParameterUniform , ParameterChordal ,   ParameterCentripetal , ParameterManhattan }
	Parametrization type 更多...

Public 成员函数
	QwtSplineParametrization (int type)
	Constructor
virtual	~QwtSplineParametrization ()
	Destructor
int	type () const
	Get the parametrization type
virtual double	valueIncrement (const QPointF &, const QPointF &) const
	Calculate the parameter value increment for 2 points

静态 Public 成员函数
static double	valueIncrementX (const QPointF &, const QPointF &)
	Calculate the ParameterX value increment for 2 points
static double	valueIncrementY (const QPointF &, const QPointF &)
	Calculate the ParameterY value increment for 2 points
static double	valueIncrementUniform (const QPointF &, const QPointF &)
	Calculate the ParameterUniform value increment
static double	valueIncrementChordal (const QPointF &, const QPointF &)
	Calculate the ParameterChordal value increment for 2 points
static double	valueIncrementCentripetal (const QPointF &, const QPointF &)
	Calculate the ParameterCentripetal value increment for 2 points
static double	valueIncrementManhattan (const QPointF &, const QPointF &)
	Calculate the ParameterManhattan value increment for 2 points

详细描述

Curve parametrization used for a spline interpolation

Parametrization is the process of finding a parameter value for each curve point - usually related to some physical quantity ( distance, time ... ).

Often accumulating the curve length is the intended way of parametrization, but as the interpolated curve is not known in advance an approximation needs to be used.

The values are calculated by cumulating increments, that are provided by QwtSplineParametrization. As the curve parameters need to be montonically increasing, each increment need to be positive.

• t[0] = 0;
• t[i] = t[i-1] + valueIncrement( point[i-1], p[i] );

QwtSplineParametrization provides the most common used type of parametrizations and offers an interface to inject custom implementations.

注解

The most relevant types of parametrization are trying to provide an approximation of the curve length.

参见

QwtSpline::setParametrization()

成员枚举类型说明

Type

enum QwtSplineParametrization::Type

Parametrization type

枚举值
ParameterX	No parametrization: t[i] = x[i] 参见 valueIncrementX()
ParameterY	No parametrization: t[i] = y[i] 参见 valueIncrementY()
ParameterUniform	Uniform parametrization: t[i] = i; A very fast parametrization, with good results, when the geometry of the control points is somehow "equidistant". F.e. when recording the position of a body, that is moving with constant speed every n seconds. 参见 valueIncrementUniform()
ParameterChordal	Parametrization using the chordal length between two control points The chordal length is the most commonly used approximation for the curve length. 参见 valueIncrementChordal()
ParameterCentripetal	Centripetal parametrization Based on the square root of the chordal length. Its name stems from the physical observations regarding the centripetal force, of a body moving along the curve. 参见 valueIncrementCentripetal()
ParameterManhattan	Parametrization using the manhattan length between two control points Approximating the curve length by the manhattan length is faster than the chordal length, but usually gives worse results. 参见 valueIncrementManhattan()

构造及析构函数说明

QwtSplineParametrization()

QwtSplineParametrization::QwtSplineParametrization ( int  type )

explicit

Constructor

Creates a spline parametrization with the specified type.

参数

[in]

type

Parametrization type

参见

type()

成员函数说明

type()

int QwtSplineParametrization::type

(

)

const

Get the parametrization type

返回

Parametrization type

valueIncrement()

double QwtSplineParametrization::valueIncrement ( const QPointF &  point1, const QPointF &  point2  ) const

virtual

Calculate the parameter value increment for 2 points

参数

[in]	point1	First point
[in]	point2	Second point

返回

Value increment

valueIncrementCentripetal()

double QwtSplineParametrization::valueIncrementCentripetal ( const QPointF &  point1, const QPointF &  point2  )

inlinestatic

Calculate the ParameterCentripetal value increment for 2 points

参数

[in]	point1	First point
[in]	point2	Second point

返回

The square root of a chordal increment

valueIncrementChordal()

double QwtSplineParametrization::valueIncrementChordal ( const QPointF &  point1, const QPointF &  point2  )

inlinestatic

Calculate the ParameterChordal value increment for 2 points

参数

[in]	point1	First point
[in]	point2	Second point

返回

qSqrt( dx * dx + dy * dy )

valueIncrementManhattan()

double QwtSplineParametrization::valueIncrementManhattan ( const QPointF &  point1, const QPointF &  point2  )

inlinestatic

Calculate the ParameterManhattan value increment for 2 points

参数

[in]	point1	First point
[in]	point2	Second point

返回

| point2.x() - point1.x() | + | point2.y() - point1.y() |

valueIncrementUniform()

double QwtSplineParametrization::valueIncrementUniform ( const QPointF &  point1, const QPointF &  point2  )

inlinestatic

Calculate the ParameterUniform value increment

参数

[in]	point1	First point
[in]	point2	Second point

返回

1.0

valueIncrementX()

double QwtSplineParametrization::valueIncrementX ( const QPointF &  point1, const QPointF &  point2  )

inlinestatic

Calculate the ParameterX value increment for 2 points

参数

[in]	point1	First point
[in]	point2	Second point

返回

point2.x() - point1.x()

valueIncrementY()

double QwtSplineParametrization::valueIncrementY ( const QPointF &  point1, const QPointF &  point2  )

inlinestatic

Calculate the ParameterY value increment for 2 points

参数

[in]	point1	First point
[in]	point2	Second point

返回

point2.y() - point1.y()

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该类的文档由以下文件生成:

• /home/runner/work/QWT/QWT/src/plot/qwt_spline_parametrization.h
• /home/runner/work/QWT/QWT/src/plot/qwt_spline_parametrization.cpp