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

NAME
       QwtSplineInterpolating - Base class for a spline interpolation.


SYNOPSIS
       #include <qwt_spline.h>

       Inherits QwtSpline.

       Inherited by QwtSplineG1.

   Public Member Functions
       QwtSplineInterpolating ()
           Constructor.
       virtual ~QwtSplineInterpolating ()
           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.

   Additional Inherited Members

Detailed Description
       Base class for a spline interpolation.

       Spline interpolation is the process of interpolating a set of points
       piecewise with polynomials. The initial set of points is preserved.

       Definition at line 193 of file qwt_spline.h.

Member Function Documentation
   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 QwtSplineCubic, QwtSplinePleasing, QwtSplineLocal,
       QwtSplineC2, and QwtSplineC1.

   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
           points Control nodes of the spline
           distance Distance between 2 points according to the parametrization
           withNodes When true, also add the control nodes ( even if not being
           equidistant )

       Returns
           Interpolating polygon

       See also
           bezierControlLines()

       Reimplemented in QwtSplineC2, and QwtSplineC1.

       Definition at line 863 of file qwt_spline.cpp.

   QPainterPath QwtSplineInterpolating::painterPath (const QPolygonF & points)
       const [override],  [virtual]
       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
           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 QwtSplinePleasing, QwtSplineLocal, QwtSplineCubic,
       QwtSplineC2, and QwtSplineC1.

       Definition at line 748 of file qwt_spline.cpp.

   QPolygonF QwtSplineInterpolating::polygon (const QPolygonF & points, double
       tolerance) const [override],  [virtual]
       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
           points Control points
           tolerance Maximum for the accepted error of the approximation

       Returns
           polygon approximating the interpolating polynomials

       See also
           bezierControlLines(), QwtSplineBezier::toPolygon()

       Reimplemented from QwtSpline.

       Definition at line 805 of file qwt_spline.cpp.


Author
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Version 6.2.0                   Sun Jul 18 2021      QwtSplineInterpolating(3)