ground/gcs/src/libs/qwt/src/qwt_curve_fitter.h

   1 /* -*- mode: C++ ; c-file-style: "stroustrup" -*- *****************************
   2  * Qwt Widget Library
   3  * Copyright (C) 1997   Josef Wilgen
   4  * Copyright (C) 2002   Uwe Rathmann
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the Qwt License, Version 1.0
   8  *****************************************************************************/
   9
  10 #ifndef QWT_CURVE_FITTER_H
  11 #define QWT_CURVE_FITTER_H
  12
  13 #include "qwt_global.h"
  14 #include <qpolygon.h>
  15 #include <qrect.h>
  16
  17 class QwtSpline;
  18
  19 /*!
  20   \brief Abstract base class for a curve fitter
  21 */
  22 class QWT_EXPORT QwtCurveFitter
  23 {
  24 public:
  25     virtual ~QwtCurveFitter();
  26
  27     /*!
  28         Find a curve which has the best fit to a series of data points
  29
  30         \param polygon Series of data points
  31         \return Curve points
  32      */
  33     virtual QPolygonF fitCurve( const QPolygonF &polygon ) const = 0;
  34
  35 protected:
  36     QwtCurveFitter();
  37
  38 private:
  39     QwtCurveFitter( const QwtCurveFitter & );
  40     QwtCurveFitter &operator=( const QwtCurveFitter & );
  41 };
  42
  43 /*!
  44   \brief A curve fitter using cubic splines
  45 */
  46 class QWT_EXPORT QwtSplineCurveFitter: public QwtCurveFitter
  47 {
  48 public:
  49     /*!
  50       Spline type
  51       The default setting is Auto
  52       \sa setFitMode(), FitMode()
  53      */
  54     enum FitMode
  55     {
  56         /*!
  57           Use the default spline algorithm for polygons with
  58           increasing x values ( p[i-1] < p[i] ), otherwise use
  59           a parametric spline algorithm.
  60          */
  61         Auto,
  62
  63         //! Use a default spline algorithm
  64         Spline,
  65
  66         //! Use a parametric spline algorithm
  67         ParametricSpline
  68     };
  69
  70     QwtSplineCurveFitter();
  71     virtual ~QwtSplineCurveFitter();
  72
  73     void setFitMode( FitMode );
  74     FitMode fitMode() const;
  75
  76     void setSpline( const QwtSpline& );
  77     const QwtSpline &spline() const;
  78     QwtSpline &spline();
  79
  80     void setSplineSize( int size );
  81     int splineSize() const;
  82
  83     virtual QPolygonF fitCurve( const QPolygonF & ) const;
  84
  85 private:
  86     QPolygonF fitSpline( const QPolygonF & ) const;
  87     QPolygonF fitParametric( const QPolygonF & ) const;
  88
  89     class PrivateData;
  90     PrivateData *d_data;
  91 };
  92
  93 /*!
  94   \brief A curve fitter implementing Douglas and Peucker algorithm
  95
  96   The purpose of the Douglas and Peucker algorithm is that given a 'curve'
  97   composed of line segments to find a curve not too dissimilar but that
  98   has fewer points. The algorithm defines 'too dissimilar' based on the
  99   maximum distance (tolerance) between the original curve and the
 100   smoothed curve.
 101
 102   The runtime of the algorithm increases non linear ( worst case O( n*n ) )
 103   and might be very slow for huge polygons. To avoid performance issues
 104   it might be useful to split the polygon ( setChunkSize() ) and to run the algorithm
 105   for these smaller parts. The disadvantage of having no interpolation
 106   at the borders is for most use cases irrelevant.
 107
 108   The smoothed curve consists of a subset of the points that defined the
 109   original curve.
 110
 111   In opposite to QwtSplineCurveFitter the Douglas and Peucker algorithm reduces
 112   the number of points. By adjusting the tolerance parameter according to the
 113   axis scales QwtSplineCurveFitter can be used to implement different
 114   level of details to speed up painting of curves of many points.
 115 */
 116 class QWT_EXPORT QwtWeedingCurveFitter: public QwtCurveFitter
 117 {
 118 public:
 119     QwtWeedingCurveFitter( double tolerance = 1.0 );
 120     virtual ~QwtWeedingCurveFitter();
 121
 122     void setTolerance( double );
 123     double tolerance() const;
 124
 125     void setChunkSize( uint );
 126     uint chunkSize() const;
 127
 128     virtual QPolygonF fitCurve( const QPolygonF & ) const;
 129
 130 private:
 131     virtual QPolygonF simplify( const QPolygonF & ) const;
 132
 133     class Line;
 134
 135     class PrivateData;
 136     PrivateData *d_data;
 137 };
 138
 139 #endif