彻底改版2.0

third/3rd_qwt/qwt_curve_fitter.h

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