QwtBezier类 参考

An implementation of the de Casteljau's Algorithm for interpolating Bézier curves 更多...

#include <qwt_bezier.h>

Public 成员函数
	QwtBezier (double tolerance=0.5)
	Constructor with tolerance parameter
	~QwtBezier ()
	Destructor
void	setTolerance (double tolerance)
	Set the tolerance for curve subdivision
double	tolerance () const
	Get the tolerance value
QPolygonF	toPolygon (const QPointF &p1, const QPointF &cp1, const QPointF &cp2, const QPointF &p2) const
	Interpolate a Bézier curve as a polygon
void	appendToPolygon (const QPointF &p1, const QPointF &cp1, const QPointF &cp2, const QPointF &p2, QPolygonF &polygon) const
	Append Bézier curve points to an existing polygon

静态 Public 成员函数
static QPointF	pointAt (const QPointF &p1, const QPointF &cp1, const QPointF &cp2, const QPointF &p2, double t)
	Find a point on a Bézier curve at parameter t

详细描述

An implementation of the de Casteljau's Algorithm for interpolating Bézier curves

The flatness criterion for terminating the subdivision is based on "Piecewise Linear Approximation of Bézier Curves" by Roger Willcocks. See: https://jeremykun.com/2013/05/11/bezier-curves-and-picasso

构造及析构函数说明

QwtBezier()

QwtBezier::QwtBezier

(

double

tolerance = 0.5

)

Constructor with tolerance parameter

Constructor

参数

tolerance

Termination criterion for the subdivision

参见

setTolerance()

成员函数说明

appendToPolygon()

void QwtBezier::appendToPolygon	(	const QPointF &	p1,
		const QPointF &	cp1,
		const QPointF &	cp2,
		const QPointF &	p2,
		QPolygonF &	polygon
	)		const

Append Bézier curve points to an existing polygon

Interpolate a Bézier curve by adding points to a polygon

appendToPolygon() is tailored for accumulating points from a sequence of Bézier curves, such as those created by spline interpolation.

参数

p1	Start point
cp1	First control point
cp2	Second control point
p2	End point
polygon	Polygon where the interpolating points are added

注解

If the last point of the incoming polygon matches p1, it won't be inserted a second time.

pointAt()

QPointF QwtBezier::pointAt ( const QPointF &  p1, const QPointF &  cp1, const QPointF &  cp2, const QPointF &  p2, double  t  )

static

Find a point on a Bézier curve at parameter t

Find a point on a Bézier curve

参数

p1	Start point
cp1	First control point
cp2	Second control point
p2	End point
t	Parameter value in range [0,1]

返回

Point on the curve

setTolerance()

void QwtBezier::setTolerance

(

double

tolerance

)

Set the tolerance for curve subdivision

The tolerance is a measurement for the flatness of a curve. A curve with a flatness below the tolerance is considered as being flat, terminating the subdivision algorithm. When interpolating a Bezier curve to render it as a sequence of lines to some sort of raster (e.g., to screen), a value of 0.5 of the pixel size is a good value for the tolerance.

参数

tolerance

Termination criterion for the subdivision

参见

tolerance()

tolerance()

double QwtBezier::tolerance ( ) const

inline

Get the tolerance value

返回

Tolerance value used for subdivision

toPolygon()

QPolygonF QwtBezier::toPolygon	(	const QPointF &	p1,
		const QPointF &	cp1,
		const QPointF &	cp2,
		const QPointF &	p2
	)		const

Interpolate a Bézier curve as a polygon

Interpolate a Bézier curve by a polygon

参数

p1	Start point
cp1	First control point
cp2	Second control point
p2	End point

返回

Interpolating polygon

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该类的文档由以下文件生成:

• /home/runner/work/QWT/QWT/src/core/qwt_bezier.h
• /home/runner/work/QWT/QWT/src/core/qwt_bezier.cpp