QwtSplineC1 - Man Page
Base class for spline interpolations providing a first order parametric continuity ( C1 ) between adjoining curves.
Synopsis
#include <qwt_spline.h>
Inherits QwtSplineG1.
Inherited by QwtSplineC2, and QwtSplineLocal.
Public Member Functions
QwtSplineC1 ()
Constructor.
virtual ~QwtSplineC1 ()
Destructor.
virtual QPainterPath painterPath (const QPolygonF &) const override
Calculate an interpolated painter path.
virtual QVector< QLineF > bezierControlLines (const QPolygonF &) const override
Interpolate a curve with Bezier curves.
virtual QPolygonF equidistantPolygon (const QPolygonF &, double distance, bool withNodes) const override
Find an interpolated polygon with 'equidistant' points.
virtual QVector< QwtSplinePolynomial > polynomials (const QPolygonF &) const
Calculate the interpolating polynomials for a non parametric spline.
virtual QVector< double > slopes (const QPolygonF &) const =0
Find the first derivative at the control points.
virtual double slopeAtBeginning (const QPolygonF &, double slopeNext) const
virtual double slopeAtEnd (const QPolygonF &, double slopeBefore) const
Additional Inherited Members
Detailed Description
Base class for spline interpolations providing a first order parametric continuity ( C1 ) between adjoining curves.
All interpolations with C1 continuity are based on rules for finding the 1. derivate at some control points.
In case of non parametric splines those points are the curve points, while for parametric splines the calculation is done twice using a parameter value t.
- See also
QwtSplineParametrization
Definition at line 235 of file qwt_spline.h.
Constructor & Destructor Documentation
QwtSplineC1::QwtSplineC1 ()
Constructor. The default setting is a non closing spline with no parametrization ( QwtSplineParametrization::ParameterX ).
- See also
QwtSpline::setParametrization(), QwtSpline::setBoundaryType()
Definition at line 962 of file qwt_spline.cpp.
Member Function Documentation
QVector< QLineF > QwtSplineC1::bezierControlLines (const QPolygonF & points) const [override], [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
Implements QwtSplineInterpolating.
Reimplemented in QwtSplineCubic, QwtSplineLocal, and QwtSplineC2.
Definition at line 1101 of file qwt_spline.cpp.
QPolygonF QwtSplineC1::equidistantPolygon (const QPolygonF & points, double distance, bool withNodes) const [override], [virtual]
Find an interpolated polygon with 'equidistant' points. The implementation is optimzed for non parametric curves ( QwtSplineParametrization::ParameterX ) and falls back to QwtSpline::equidistantPolygon() otherwise.
- 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
QwtSpline::equidistantPolygon()
Reimplemented from QwtSplineInterpolating.
Reimplemented in QwtSplineC2.
Definition at line 1167 of file qwt_spline.cpp.
QPainterPath QwtSplineC1::painterPath (const QPolygonF & points) const [override], [virtual]
Calculate an interpolated painter path. Interpolates a polygon piecewise into cubic Bezier curves and returns them as QPainterPath.
The implementation calculates the slopes at the control points and converts them into painter path elements in an additional loop.
- Parameters
points Control points
- Returns
QPainterPath 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
Reimplemented from QwtSplineInterpolating.
Reimplemented in QwtSplineLocal, QwtSplineCubic, and QwtSplineC2.
Definition at line 1043 of file qwt_spline.cpp.
QVector< QwtSplinePolynomial > QwtSplineC1::polynomials (const QPolygonF & points) const [virtual]
Calculate the interpolating polynomials for a non parametric spline. C1 spline interpolations are based on finding values for the first derivates at the control points. The interpolating polynomials can be calculated from the the first derivates using QwtSplinePolynomial::fromSlopes().
The default implementation is a two pass calculation. In derived classes it might be overloaded by a one pass implementation.
- Parameters
points Control points
- Returns
Interpolating polynomials
- Note
The x coordinates need to be increasing or decreasing
Reimplemented in QwtSplineLocal, QwtSplineCubic, and QwtSplineC2.
Definition at line 1201 of file qwt_spline.cpp.
double QwtSplineC1::slopeAtBeginning (const QPolygonF & points, double slopeNext) const [virtual]
- Parameters
points Control points
slopeNext Value of the first derivative at the second point- Returns
value of the first derivative at the first point
- See also
slopeAtEnd(), QwtSpline::boundaryCondition(), QwtSpline::boundaryValue()
Definition at line 979 of file qwt_spline.cpp.
double QwtSplineC1::slopeAtEnd (const QPolygonF & points, double slopeBefore) const [virtual]
- Parameters
points Control points
slopeBefore Value of the first derivative at the point before the last one- Returns
value of the first derivative at the last point
- See also
slopeAtBeginning(), QwtSpline::boundaryCondition(), QwtSpline::boundaryValue()
Definition at line 997 of file qwt_spline.cpp.
QVector< double > QwtSplineC1::slopes (const QPolygonF & points) const [pure virtual]
Find the first derivative at the control points.
- Parameters
points Control nodes of the spline
- Returns
Vector with the values of the 2nd derivate at the control points
- Note
The x coordinates need to be increasing or decreasing
Implemented in QwtSplineLocal, QwtSplineCubic, and QwtSplineC2.
Author
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