qwt_spline_parametrization.h

/******************************************************************************
 * Qwt Widget Library
 * Copyright (C) 1997   Josef Wilgen
 * Copyright (C) 2002   Uwe Rathmann
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the Qwt License, Version 1.0
 *
 * Modified by ChenZongYan in 2024 <czy.t@163.com>
 *   Summary of major modifications (see ChangeLog.md for full history):
 *   1. CMake build system & C++11 throughout.
 *   2. Core panner/ zoomer refactored:
 *        - QwtPanner → QwtCachePanner (pixmap-cache version)
 *        - New real-time QwtPlotPanner derived from QwtPicker.
 *   3. Zoomer supports multi-axis.
 *   4. Parasite-plot framework:
 *        - QwtFigure, QwtPlotParasiteLayout, QwtPlotTransparentCanvas,
 *        - QwtPlotScaleEventDispatcher, built-in pan/zoom on axis.
 *   5. New picker: QwtPlotSeriesDataPicker (works with date axis).
 *   6. Raster & color-map extensions:
 *        - QwtGridRasterData (2-D table + interpolation)
 *        - QwtLinearColorMap::stopColors(), stopPos() API rename.
 *   7. Bar-chart: expose pen/brush control.
 *   8. Amalgamated build: single QwtPlot.h / QwtPlot.cpp pair in src-amalgamate.
 *****************************************************************************/
 
#ifndef QWT_SPLINE_PARAMETRIZATION_H
#define QWT_SPLINE_PARAMETRIZATION_H
 
#include "qwt_global.h"
#include "qwt_math.h"
 
#include <qpoint.h>
 
class QWT_EXPORT QwtSplineParametrization
{
  public:
    enum Type
    {
        ParameterX,
 
        ParameterY,
 
        ParameterUniform,
 
        ParameterChordal,
 
        ParameterCentripetal,
 
 
        ParameterManhattan
    };
 
    // Constructor with parametrization type
    explicit QwtSplineParametrization( int type );
    // Destructor
    virtual ~QwtSplineParametrization();
 
    // Get parametrization type
    int type() const;
 
    // Calculate parameter value increment for 2 points
    virtual double valueIncrement( const QPointF&, const QPointF& ) const;
 
    static double valueIncrementX( const QPointF&, const QPointF& );
    static double valueIncrementY( const QPointF&, const QPointF& );
    static double valueIncrementUniform( const QPointF&, const QPointF& );
    static double valueIncrementChordal( const QPointF&, const QPointF& );
    static double valueIncrementCentripetal( const QPointF&, const QPointF& );
    static double valueIncrementManhattan( const QPointF&, const QPointF& );
 
  private:
    const int m_type;
};
 
inline double QwtSplineParametrization::valueIncrementX(
    const QPointF& point1, const QPointF& point2 )
{
    return point2.x() - point1.x();
}
 
inline double QwtSplineParametrization::valueIncrementY(
    const QPointF& point1, const QPointF& point2 )
{
    return point2.y() - point1.y();
}
 
inline double QwtSplineParametrization::valueIncrementUniform(
    const QPointF& point1, const QPointF& point2 )
{
    Q_UNUSED( point1 )
    Q_UNUSED( point2 )
 
    return 1.0;
}
 
inline double QwtSplineParametrization::valueIncrementChordal(
    const QPointF& point1, const QPointF& point2 )
{
    const double dx = point2.x() - point1.x();
    const double dy = point2.y() - point1.y();
 
    return std::sqrt( dx * dx + dy * dy );
}
 
inline double QwtSplineParametrization::valueIncrementCentripetal(
    const QPointF& point1, const QPointF& point2 )
{
    return std::sqrt( valueIncrementChordal( point1, point2 ) );
}
 
inline double QwtSplineParametrization::valueIncrementManhattan(
    const QPointF& point1, const QPointF& point2 )
{
    return qAbs( point2.x() - point1.x() ) + qAbs( point2.y() - point1.y() );
}
 
#endif