qwt_double_interval.cpp

/* -*- 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
 *****************************************************************************/

#include <qglobal.h>
#if QT_VERSION >= 0x040000
#include <qalgorithms.h>
#else
#include <qtl.h>
#endif

#include "qwt_math.h"
#include "qwt_double_interval.h"

/*!
   \brief Normalize the limits of the interval

   If maxValue() < minValue() the limits will be inverted.
   \return Normalized interval

   \sa isValid, inverted
*/
QwtDoubleInterval QwtDoubleInterval::normalized() const
{
    if ( !isValid() )
    {
        return QwtDoubleInterval(d_maxValue, d_minValue);
    }
    else
        return *this;
}

/*!
   Invert the limits of the interval
   \return Inverted interval
   \sa normalized
*/
QwtDoubleInterval QwtDoubleInterval::inverted() const
{
    return QwtDoubleInterval(d_maxValue, d_minValue);
}

/*!
  Test if a value is inside an interval

  \param value Value
  \return true, if value >= minValue() && value <= maxValue()
*/
bool QwtDoubleInterval::contains(double value) const
{
    if ( !isValid() )
        return false;

    return (value >= d_minValue) && (value <= d_maxValue);
}

//! Unite 2 intervals
QwtDoubleInterval QwtDoubleInterval::unite(
    const QwtDoubleInterval &interval) const
{
    if ( !isValid() )
    {
        if ( !interval.isValid() )
            return QwtDoubleInterval();
        else
            return interval;
    }
    if ( !interval.isValid() )
        return *this;

    const double minValue = qwtMin(d_minValue, interval.minValue());
    const double maxValue = qwtMax(d_maxValue, interval.maxValue());

    return QwtDoubleInterval(minValue, maxValue);
}

//! Intersect 2 intervals
QwtDoubleInterval QwtDoubleInterval::intersect(
    const QwtDoubleInterval &interval) const
{
    if ( !interval.isValid() || !isValid() )
        return QwtDoubleInterval();

    QwtDoubleInterval i1 = *this;
    QwtDoubleInterval i2 = interval;

    if ( i1.minValue() > i2.minValue() )
        qSwap(i1, i2);

    if ( i1.maxValue() < i2.minValue() )
        return QwtDoubleInterval();

    return QwtDoubleInterval(i2.minValue(), 
                qwtMin(i1.maxValue(), i2.maxValue()));
}

QwtDoubleInterval& QwtDoubleInterval::operator|=(
    const QwtDoubleInterval &interval)
{
    *this = *this | interval;
    return *this;
}

QwtDoubleInterval& QwtDoubleInterval::operator&=(
    const QwtDoubleInterval &interval) 
{
    *this = *this & interval;
    return *this;
}

/*!
   Test if two intervals overlap
*/
bool QwtDoubleInterval::intersects(const QwtDoubleInterval &interval) const
{
    if ( !isValid() || !interval.isValid() )
        return false;

    QwtDoubleInterval i1 = *this;
    QwtDoubleInterval i2 = interval;

    if ( i1.minValue() > i2.minValue() )
        qSwap(i1, i2);

    return i1.maxValue() >= i2.minValue();
}

/*!
   Adjust the limit that is closer to value, so that value becomes
   the center of the interval.

   \param value Center
   \return Interval with value as center
*/
QwtDoubleInterval QwtDoubleInterval::symmetrize(double value) const
{
    if ( !isValid() )
        return *this;

    const double delta =
        qwtMax(qwtAbs(value - d_maxValue), qwtAbs(value - d_minValue));

    return QwtDoubleInterval(value - delta, value + delta);
}

/*!
   Limit the interval

   \param lBound Lower limit
   \param hBound Upper limit

   \return Limited interval
*/
QwtDoubleInterval QwtDoubleInterval::limited(
    double lBound, double hBound) const
{
    if ( !isValid() || lBound > hBound )
        return QwtDoubleInterval();

    double minValue = qwtMax(d_minValue, lBound);
    minValue = qwtMin(minValue, hBound);

    double maxValue = qwtMax(d_maxValue, lBound);
    maxValue = qwtMin(maxValue, hBound);

    return QwtDoubleInterval(minValue, maxValue);
}

/*!
   Extend the interval

   If value is below minValue, value becomes the lower limit.
   If value is above maxValue, value becomes the upper limit.

   extend has no effect for invalid intervals

   \param value Value
   \sa isValid
*/
QwtDoubleInterval QwtDoubleInterval::extend(double value) const
{
    if ( !isValid() )
        return *this;

    return QwtDoubleInterval(
        qwtMin(value, d_minValue), qwtMax(value, d_maxValue) );
}

QwtDoubleInterval& QwtDoubleInterval::operator|=(double value)
{
    *this = *this | value;
    return *this;
}