qwt_curve_fitter.cpp

/* -*- mode: C++ ; c-file-style: "stroustrup" -*- *****************************
 * 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
 *****************************************************************************/

#include "qwt_math.h"
#include "qwt_spline.h"
#include "qwt_curve_fitter.h"

//! Constructor
QwtCurveFitter::QwtCurveFitter()
{
}

//! Destructor
QwtCurveFitter::~QwtCurveFitter()
{
}

class QwtSplineCurveFitter::PrivateData
{
public:
    PrivateData():
        fitMode(QwtSplineCurveFitter::Auto),
        splineSize(250) {
    }

    QwtSpline spline;
    QwtSplineCurveFitter::FitMode fitMode;
    int splineSize;
};

QwtSplineCurveFitter::QwtSplineCurveFitter()
{
    d_data = new PrivateData;
}

QwtSplineCurveFitter::~QwtSplineCurveFitter()
{
    delete d_data;
}

void QwtSplineCurveFitter::setFitMode(FitMode mode)
{
    d_data->fitMode = mode;
}

QwtSplineCurveFitter::FitMode QwtSplineCurveFitter::fitMode() const
{
    return d_data->fitMode;
}

void QwtSplineCurveFitter::setSpline(const QwtSpline &spline)
{
    d_data->spline = spline;
    d_data->spline.reset();
}

const QwtSpline &QwtSplineCurveFitter::spline() const
{
    return d_data->spline;
}

QwtSpline &QwtSplineCurveFitter::spline()
{
    return d_data->spline;
}

void QwtSplineCurveFitter::setSplineSize(int splineSize)
{
    d_data->splineSize = qwtMax(splineSize, 10);
}

int QwtSplineCurveFitter::splineSize() const
{
    return d_data->splineSize;
}

#if QT_VERSION < 0x040000
QwtArray<QwtDoublePoint> QwtSplineCurveFitter::fitCurve(
    const QwtArray<QwtDoublePoint> & points) const
#else
QPolygonF QwtSplineCurveFitter::fitCurve(
    const QPolygonF &points) const
#endif
{
    const int size = (int)points.size();
    if ( size <= 2 )
        return points;

    FitMode fitMode = d_data->fitMode;
    if ( fitMode == Auto ) {
        fitMode = Spline;

        const QwtDoublePoint *p = points.data();
        for ( int i = 1; i < size; i++ ) {
            if ( p[i].x() <= p[i-1].x() ) {
                fitMode = ParametricSpline;
                break;
            }
        };
    }

    if ( fitMode == ParametricSpline )
        return fitParametric(points);
    else
        return fitSpline(points);
}

#if QT_VERSION < 0x040000
QwtArray<QwtDoublePoint> QwtSplineCurveFitter::fitSpline(
    const QwtArray<QwtDoublePoint> &points) const
#else
QPolygonF QwtSplineCurveFitter::fitSpline(
    const QPolygonF &points) const
#endif
{
    d_data->spline.setPoints(points);
    if ( !d_data->spline.isValid() )
        return points;

#if QT_VERSION < 0x040000
    QwtArray<QwtDoublePoint> fittedPoints(d_data->splineSize);
#else
    QPolygonF fittedPoints(d_data->splineSize);
#endif

    const double x1 = points[0].x();
    const double x2 = points[int(points.size() - 1)].x();
    const double dx = x2 - x1;
    const double delta = dx / (d_data->splineSize - 1);

    for (int i = 0; i < d_data->splineSize; i++) {
        QwtDoublePoint &p = fittedPoints[i];

        const double v = x1 + i * delta;
        const double sv = d_data->spline.value(v);

        p.setX(qRound(v));
        p.setY(qRound(sv));
    }
    d_data->spline.reset();

    return fittedPoints;
}

#if QT_VERSION < 0x040000
QwtArray<QwtDoublePoint> QwtSplineCurveFitter::fitParametric(
    const QwtArray<QwtDoublePoint> &points) const
#else
QPolygonF QwtSplineCurveFitter::fitParametric(
    const QPolygonF &points) const
#endif
{
    int i;
    const int size = points.size();

#if QT_VERSION < 0x040000
    QwtArray<QwtDoublePoint> fittedPoints(d_data->splineSize);
    QwtArray<QwtDoublePoint> splinePointsX(size);
    QwtArray<QwtDoublePoint> splinePointsY(size);
#else
    QPolygonF fittedPoints(d_data->splineSize);
    QPolygonF splinePointsX(size);
    QPolygonF splinePointsY(size);
#endif

    const QwtDoublePoint *p = points.data();
    QwtDoublePoint *spX = splinePointsX.data();
    QwtDoublePoint *spY = splinePointsY.data();

    double param = 0.0;
    for (i = 0; i < size; i++) {
        const double x = p[i].x();
        const double y = p[i].y();
        if ( i > 0 ) {
            const double delta = sqrt( qwtSqr(x - spX[i-1].y())
                                       + qwtSqr( y - spY[i-1].y() ) );
            param += qwtMax(delta, 1.0);
        }
        spX[i].setX(param);
        spX[i].setY(x);
        spY[i].setX(param);
        spY[i].setY(y);
    }

    d_data->spline.setPoints(splinePointsX);
    if ( !d_data->spline.isValid() )
        return points;

    const double deltaX =
        splinePointsX[size - 1].x() / (d_data->splineSize-1);
    for (i = 0; i < d_data->splineSize; i++) {
        const double dtmp = i * deltaX;
        fittedPoints[i].setX(qRound(d_data->spline.value(dtmp)));
    }

    d_data->spline.setPoints(splinePointsY);
    if ( !d_data->spline.isValid() )
        return points;

    const double deltaY =
        splinePointsY[size - 1].x() / (d_data->splineSize-1);
    for (i = 0; i < d_data->splineSize; i++) {
        const double dtmp = i * deltaY;
        fittedPoints[i].setY(qRound(d_data->spline.value(dtmp)));
    }

    return fittedPoints;
}