qwt_scale_map.h

/* -*- 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_SCALE_MAP_H
#define QWT_SCALE_MAP_H

#include "qwt_global.h"
#include "qwt_transform.h"
#include <qrect.h>

#ifndef QT_NO_DEBUG_STREAM
#include <qdebug.h>
#endif

class QRectF;

/*!
   \brief A scale map

   QwtScaleMap offers transformations from the coordinate system
   of a scale into the linear coordinate system of a paint device 
   and vice versa.
*/
class QWT_EXPORT QwtScaleMap
{
public:
    QwtScaleMap();
    QwtScaleMap( const QwtScaleMap& );

    ~QwtScaleMap();

    QwtScaleMap &operator=( const QwtScaleMap & );

    void setTransformation( QwtTransform * );
    const QwtTransform *transformation() const;

    void setPaintInterval( double p1, double p2 );
    void setScaleInterval( double s1, double s2 );

    double transform( double s ) const;
    double invTransform( double p ) const;

    double p1() const;
    double p2() const;

    double s1() const;
    double s2() const;

    double pDist() const;
    double sDist() const;

    static QRectF transform( const QwtScaleMap &,
        const QwtScaleMap &, const QRectF & );
    static QRectF invTransform( const QwtScaleMap &,
        const QwtScaleMap &, const QRectF & );

    static QPointF transform( const QwtScaleMap &,
        const QwtScaleMap &, const QPointF & );
    static QPointF invTransform( const QwtScaleMap &,
        const QwtScaleMap &, const QPointF & );

    bool isInverting() const;

private:
    void updateFactor();

    double d_s1, d_s2;     // scale interval boundaries
    double d_p1, d_p2;     // paint device interval boundaries

    double d_cnv;       // conversion factor
    double d_ts1;

    QwtTransform *d_transform;
};

/*!
    \return First border of the scale interval
*/
inline double QwtScaleMap::s1() const
{
    return d_s1;
}

/*!
    \return Second border of the scale interval
*/
inline double QwtScaleMap::s2() const
{
    return d_s2;
}

/*!
    \return First border of the paint interval
*/
inline double QwtScaleMap::p1() const
{
    return d_p1;
}

/*!
    \return Second border of the paint interval
*/
inline double QwtScaleMap::p2() const
{
    return d_p2;
}

/*!
    \return qwtAbs(p2() - p1())
*/
inline double QwtScaleMap::pDist() const
{
    return qAbs( d_p2 - d_p1 );
}

/*!
    \return qwtAbs(s2() - s1())
*/
inline double QwtScaleMap::sDist() const
{
    return qAbs( d_s2 - d_s1 );
}

/*!
  Transform a point related to the scale interval into an point
  related to the interval of the paint device

  \param s Value relative to the coordinates of the scale
  \return Transformed value

  \sa invTransform()
*/
inline double QwtScaleMap::transform( double s ) const
{
    if ( d_transform )
        s = d_transform->transform( s );

    return d_p1 + ( s - d_ts1 ) * d_cnv;
}

/*!
  Transform an paint device value into a value in the
  interval of the scale.

  \param p Value relative to the coordinates of the paint device
  \return Transformed value

  \sa transform()
*/
inline double QwtScaleMap::invTransform( double p ) const
{
    double s = d_ts1 + ( p - d_p1 ) / d_cnv;
    if ( d_transform )
        s = d_transform->invTransform( s );

    return s;
}

//! \return True, when ( p1() < p2() ) != ( s1() < s2() )
inline bool QwtScaleMap::isInverting() const
{
    return ( ( d_p1 < d_p2 ) != ( d_s1 < d_s2 ) );
}

#ifndef QT_NO_DEBUG_STREAM
QWT_EXPORT QDebug operator<<( QDebug, const QwtScaleMap & );
#endif

#endif