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33fc476d89
* require qwt >=6.2 (and fallback to internal 6.3 if system's qwt doesn't suffice) * debian doesn't have qwt for Qt6 and won't have it for trixie
63 lines
2.2 KiB
C++
63 lines
2.2 KiB
C++
/******************************************************************************
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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_WEEDING_CURVE_FITTER_H
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#define QWT_WEEDING_CURVE_FITTER_H
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#include "qwt_curve_fitter.h"
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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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explicit 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 QWT_OVERRIDE;
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virtual QPainterPath fitCurvePath( const QPolygonF& ) const QWT_OVERRIDE;
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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* m_data;
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};
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#endif
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