QwtBezier(3)                   Qwt User's Guide                   QwtBezier(3)

NAME
       QwtBezier - An implementation of the de Casteljau's Algorithm for
       interpolating Bezier curves.


SYNOPSIS
       #include <qwt_bezier.h>

   Public Member Functions
       QwtBezier (double tolerance=0.5)
           Constructor.
       ~QwtBezier ()
           Destructor.
       void setTolerance (double tolerance)
       double tolerance () const
       QPolygonF toPolygon (const QPointF &p1, const QPointF &cp1, const
           QPointF &cp2, const QPointF &p2) const
           Interpolate a Bezier curve by a polygon.
       void appendToPolygon (const QPointF &p1, const QPointF &cp1, const
           QPointF &cp2, const QPointF &p2, QPolygonF &polygon) const
           Interpolate a Bezier curve by a polygon.

   Static Public Member Functions
       static QPointF pointAt (const QPointF &p1, const QPointF &cp1, const
           QPointF &cp2, const QPointF &p2, double t)

Detailed Description
       An implementation of the de Casteljau's Algorithm for interpolating
       Bezier curves.

       The flatness criterion for terminating the subdivision is based on
       'Piecewise Linear Approximation of Bezier Curves' by Roger Willcocks (
       http://www.rops.org )

       This article explains the maths behind in a very nice way:
       https://jeremykun.com/2013/05/11/bezier-curves-and-picasso

       Definition at line 29 of file qwt_bezier.h.

Constructor & Destructor Documentation
   QwtBezier::QwtBezier (double tolerance = 0.5)
       Constructor.

       Parameters
           tolerance Termination criterion for the subdivision

       See also
           setTolerance()

       Definition at line 116 of file qwt_bezier.cpp.

Member Function Documentation
   void QwtBezier::appendToPolygon (const QPointF & p1, const QPointF & cp1,
       const QPointF & cp2, const QPointF & p2, QPolygonF & polygon) const
       Interpolate a Bezier curve by a polygon. appendToPolygon() is tailored
       for cumulating points from a sequence of bezier curves like being
       created by a spline interpolation.

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

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

       Definition at line 186 of file qwt_bezier.cpp.

   QPointF QwtBezier::pointAt (const QPointF & p1, const QPointF & cp1, const
       QPointF & cp2, const QPointF & p2, double t) [static]
       Find a point on a Bezier Curve

       Parameters
           p1 Start point
           cp1 First control point
           cp2 Second control point
           p2 End point
           t Parameter value, something between [0,1]

       Returns
           Point on the curve

       Definition at line 239 of file qwt_bezier.cpp.

   void QwtBezier::setTolerance (double tolerance)
       Set the tolerance

       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 ( f.e to screen ) a value of 0.5 of the pixel
       size is a good value for the tolerance.

       Parameters
           tolerance Termination criterion for the subdivision

       See also
           tolerance()

       Definition at line 141 of file qwt_bezier.cpp.

   double QwtBezier::tolerance () const [inline]
       Returns
           Tolerance, that is used as criterion for the subdivision

       See also
           setTolerance()

       Definition at line 56 of file qwt_bezier.h.

   QPolygonF QwtBezier::toPolygon (const QPointF & p1, const QPointF & cp1,
       const QPointF & cp2, const QPointF & p2) const
       Interpolate a Bezier curve by a polygon.

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

       Returns
           Interpolating polygon

       Definition at line 157 of file qwt_bezier.cpp.


Author
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       code.

Version 6.2.0                   Sun Jul 18 2021                   QwtBezier(3)