QwtWeedingCurveFitter类 参考

A curve fitter implementing Douglas and Peucker algorithm 更多...

#include <qwt_weeding_curve_fitter.h>

类 QwtWeedingCurveFitter 继承关系图:

类
class	Line
class	PrivateData

Public 成员函数
	QwtWeedingCurveFitter (double tolerance=1.0)
	Constructor
void	setTolerance (double)
	Assign the tolerance
double	tolerance () const
void	setChunkSize (uint)
	Limit the number of points passed to a run of the algorithm
uint	chunkSize () const
virtual QPolygonF	fitCurve (const QPolygonF &) const override
virtual QPainterPath	fitCurvePath (const QPolygonF &) const override
Public 成员函数 继承自 QwtCurveFitter
virtual	~QwtCurveFitter ()
	Destructor
Mode	mode () const
	Get the preferred fitting mode

额外继承的成员函数
Public 类型 继承自 QwtCurveFitter
enum	Mode { Polygon , Path }
	Preferred mode of the fitting algorithm 更多...
Protected 成员函数 继承自 QwtCurveFitter
	QwtCurveFitter (Mode mode)
	Constructor

详细描述

A curve fitter implementing Douglas and Peucker algorithm

The purpose of the Douglas and Peucker algorithm is that given a 'curve' composed of line segments to find a curve not too dissimilar but that has fewer points. The algorithm defines 'too dissimilar' based on the maximum distance (tolerance) between the original curve and the smoothed curve.

The runtime of the algorithm increases non linear ( worst case O( n*n ) ) and might be very slow for huge polygons. To avoid performance issues it might be useful to split the polygon ( setChunkSize() ) and to run the algorithm for these smaller parts. The disadvantage of having no interpolation at the borders is for most use cases irrelevant.

The smoothed curve consists of a subset of the points that defined the original curve.

In opposite to QwtSplineCurveFitter the Douglas and Peucker algorithm reduces the number of points. By adjusting the tolerance parameter according to the axis scales QwtSplineCurveFitter can be used to implement different level of details to speed up painting of curves of many points.

构造及析构函数说明

QwtWeedingCurveFitter()

QwtWeedingCurveFitter::QwtWeedingCurveFitter ( double  tolerance = 1.0 )

explicit

Constructor

参数

tolerance

Tolerance

参见

setTolerance(), tolerance()

Destructor

成员函数说明

chunkSize()

uint QwtWeedingCurveFitter::chunkSize

(

)

const

返回

Maximum for the number of points passed to a run of the algorithm - or 0, when unlimited

参见

setChunkSize()

fitCurve()

QPolygonF QwtWeedingCurveFitter::fitCurve ( const QPolygonF &  points ) const

overridevirtual

参数

points

Series of data points

返回

Curve points

参见

fitCurvePath()

实现了 QwtCurveFitter.

fitCurvePath()

QPainterPath QwtWeedingCurveFitter::fitCurvePath ( const QPolygonF &  points ) const

overridevirtual

参数

points

Series of data points

返回

Curve path

参见

fitCurve()

实现了 QwtCurveFitter.

setChunkSize()

void QwtWeedingCurveFitter::setChunkSize

(

uint

numPoints

)

Limit the number of points passed to a run of the algorithm

The runtime of the Douglas Peucker algorithm increases non linear with the number of points. For a chunk size > 0 the polygon is split into pieces passed to the algorithm one by one.

参数

numPoints

Maximum for the number of points passed to the algorithm

参见

chunkSize()

setTolerance()

void QwtWeedingCurveFitter::setTolerance

(

double

tolerance

)

Assign the tolerance

The tolerance is the maximum distance, that is acceptable between the original curve and the smoothed curve.

Increasing the tolerance will reduce the number of the resulting points.

参数

tolerance

Tolerance

参见

tolerance()

tolerance()

double QwtWeedingCurveFitter::tolerance

(

)

const

返回

Tolerance

参见

setTolerance()

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该类的文档由以下文件生成:

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