qwt_transform.h

/******************************************************************************
 * 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
 *
 * Modified by ChenZongYan in 2024 <czy.t@163.com>
 *   Summary of major modifications (see ChangeLog.md for full history):
 *   1. CMake build system & C++11 throughout.
 *   2. Core panner/ zoomer refactored:
 *        - QwtPanner → QwtCachePanner (pixmap-cache version)
 *        - New real-time QwtPlotPanner derived from QwtPicker.
 *   3. Zoomer supports multi-axis.
 *   4. Parasite-plot framework:
 *        - QwtFigure, QwtPlotParasiteLayout, QwtPlotTransparentCanvas,
 *        - QwtPlotScaleEventDispatcher, built-in pan/zoom on axis.
 *   5. New picker: QwtPlotSeriesDataPicker (works with date axis).
 *   6. Raster & color-map extensions:
 *        - QwtGridRasterData (2-D table + interpolation)
 *        - QwtLinearColorMap::stopColors(), stopPos() API rename.
 *   7. Bar-chart: expose pen/brush control.
 *   8. Amalgamated build: single QwtPlot.h / QwtPlot.cpp pair in src-amalgamate.
 *****************************************************************************/
 
#ifndef QWT_TRANSFORM_H
#define QWT_TRANSFORM_H
 
#include "qwtcore_global.h"
 
class QWTCORE_EXPORT QwtTransform
{
public:
    QwtTransform();
    virtual ~QwtTransform();
 
    virtual double bounded(double value) const;
    virtual double transform(double value) const = 0;
    virtual double invTransform(double value) const = 0;
    virtual QwtTransform* copy() const = 0;
 
private:
    QwtTransform(const QwtTransform&)            = delete;
    QwtTransform& operator=(const QwtTransform&) = delete;
};
 
class QWTCORE_EXPORT QwtNullTransform : public QwtTransform
{
public:
    QwtNullTransform();
    ~QwtNullTransform() override;
 
    virtual double transform(double value) const override;
    virtual double invTransform(double value) const override;
    virtual QwtTransform* copy() const override;
};
class QWTCORE_EXPORT QwtLogTransform : public QwtTransform
{
public:
    QwtLogTransform();
    ~QwtLogTransform() override;
 
    virtual double transform(double value) const override;
    virtual double invTransform(double value) const override;
    virtual double bounded(double value) const override;
    virtual QwtTransform* copy() const override;
 
    static const double LogMin;
    static const double LogMax;
};
 
class QWTCORE_EXPORT QwtPowerTransform : public QwtTransform
{
public:
    explicit QwtPowerTransform(double exponent);
    ~QwtPowerTransform() override;
 
    virtual double transform(double value) const override;
    virtual double invTransform(double value) const override;
    virtual QwtTransform* copy() const override;
 
private:
    const double m_exponent;
};
 
#endif