140 lines
3.7 KiB
C++
140 lines
3.7 KiB
C++
/* -*- mode: C++ ; c-file-style: "stroustrup" -*- *****************************
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* Qwt Widget Library
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* Copyright (C) 1997 Josef Wilgen
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* Copyright (C) 2002 Uwe Rathmann
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the Qwt License, Version 1.0
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*****************************************************************************/
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#ifndef QWT_CURVE_FITTER_H
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#define QWT_CURVE_FITTER_H
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#include "qwt_global.h"
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#include <qpolygon.h>
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#include <qrect.h>
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class QwtSpline;
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/*!
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\brief Abstract base class for a curve fitter
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*/
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class QWT_EXPORT QwtCurveFitter
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{
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public:
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virtual ~QwtCurveFitter();
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/*!
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Find a curve which has the best fit to a series of data points
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\param polygon Series of data points
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\return Curve points
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*/
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virtual QPolygonF fitCurve( const QPolygonF &polygon ) const = 0;
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protected:
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QwtCurveFitter();
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private:
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QwtCurveFitter( const QwtCurveFitter & );
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QwtCurveFitter &operator=( const QwtCurveFitter & );
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};
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/*!
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\brief A curve fitter using cubic splines
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*/
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class QWT_EXPORT QwtSplineCurveFitter: public QwtCurveFitter
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{
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public:
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/*!
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Spline type
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The default setting is Auto
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\sa setFitMode(), FitMode()
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*/
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enum FitMode
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{
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/*!
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Use the default spline algorithm for polygons with
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increasing x values ( p[i-1] < p[i] ), otherwise use
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a parametric spline algorithm.
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*/
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Auto,
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//! Use a default spline algorithm
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Spline,
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//! Use a parametric spline algorithm
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ParametricSpline
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};
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QwtSplineCurveFitter();
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virtual ~QwtSplineCurveFitter();
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void setFitMode( FitMode );
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FitMode fitMode() const;
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void setSpline( const QwtSpline& );
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const QwtSpline &spline() const;
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QwtSpline &spline();
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void setSplineSize( int );
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int splineSize() const;
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virtual QPolygonF fitCurve( const QPolygonF & ) const;
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private:
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QPolygonF fitSpline( const QPolygonF & ) const;
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QPolygonF fitParametric( const QPolygonF & ) const;
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class PrivateData;
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PrivateData *d_data;
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};
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/*!
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\brief A curve fitter implementing Douglas and Peucker algorithm
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The purpose of the Douglas and Peucker algorithm is that given a 'curve'
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composed of line segments to find a curve not too dissimilar but that
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has fewer points. The algorithm defines 'too dissimilar' based on the
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maximum distance (tolerance) between the original curve and the
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smoothed curve.
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The runtime of the algorithm increases non linear ( worst case O( n*n ) )
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and might be very slow for huge polygons. To avoid performance issues
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it might be useful to split the polygon ( setChunkSize() ) and to run the algorithm
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for these smaller parts. The disadvantage of having no interpolation
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at the borders is for most use cases irrelevant.
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The smoothed curve consists of a subset of the points that defined the
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original curve.
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In opposite to QwtSplineCurveFitter the Douglas and Peucker algorithm reduces
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the number of points. By adjusting the tolerance parameter according to the
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axis scales QwtSplineCurveFitter can be used to implement different
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level of details to speed up painting of curves of many points.
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*/
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class QWT_EXPORT QwtWeedingCurveFitter: public QwtCurveFitter
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{
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public:
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QwtWeedingCurveFitter( double tolerance = 1.0 );
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virtual ~QwtWeedingCurveFitter();
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void setTolerance( double );
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double tolerance() const;
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void setChunkSize( uint );
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uint chunkSize() const;
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virtual QPolygonF fitCurve( const QPolygonF & ) const;
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private:
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virtual QPolygonF simplify( const QPolygonF & ) const;
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class Line;
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class PrivateData;
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PrivateData *d_data;
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};
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#endif
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