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/* -*- mode: C++ ; c-file-style: "stroustrup" -*- *****************************
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* Copyright (C) 1997 Josef Wilgen
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* Copyright (C) 2002 Uwe Rathmann
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the Qwt License, Version 1.0
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*****************************************************************************/
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#include "qwt_double_range.h"
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static double MinRelStep = 1.0e-10;
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static double DefaultRelStep = 1.0e-2;
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static double MinEps = 1.0e-10;
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The range is initialized to [0.0, 100.0], the
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step size to 1.0, and the value to 0.0.
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QwtDoubleRange::QwtDoubleRange():
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d_exactPrevValue(0.0),
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//! Destroys the QwtDoubleRange
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QwtDoubleRange::~QwtDoubleRange()
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//! Set the value to be valid/invalid
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void QwtDoubleRange::setValid(bool isValid)
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if ( isValid != d_isValid )
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//! Indicates if the value is valid
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bool QwtDoubleRange::isValid() const
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void QwtDoubleRange::setNewValue(double x, bool align)
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d_prevValue = d_value;
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vmin = qwtMin(d_minValue, d_maxValue);
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vmax = qwtMax(d_minValue, d_maxValue);
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if ((d_periodic) && (vmin != vmax))
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d_value = x + ::ceil( (vmin - x) / (vmax - vmin ) )
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if ((d_periodic) && (vmin != vmax))
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d_value = x - ::ceil( ( x - vmax) / (vmax - vmin ))
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d_exactPrevValue = d_exactValue;
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d_exactValue = d_value;
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d_value = d_minValue +
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qwtRound((d_value - d_minValue) / d_step) * d_step;
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d_value = d_minValue;
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// correct rounding error at the border
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if (fabs(d_value - d_maxValue) < MinEps * qwtAbs(d_step))
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d_value = d_maxValue;
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// correct rounding error if value = 0
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if (::fabs(d_value) < MinEps * qwtAbs(d_step))
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if (!d_isValid || d_prevValue != d_value)
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\brief Adjust the value to the closest point in the step raster.
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\warning The value is clipped when it lies outside the range.
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When the range is QwtDoubleRange::periodic, it will
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be mapped to a point in the interval such that
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\verbatim new value := x + n * (max. value - min. value)\endverbatim
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with an integer number n.
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void QwtDoubleRange::fitValue(double x)
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setNewValue(x, true);
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\brief Set a new value without adjusting to the step raster
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\warning The value is clipped when it lies outside the range.
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When the range is QwtDoubleRange::periodic, it will
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be mapped to a point in the interval such that
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\verbatim new value := x + n * (max. value - min. value)\endverbatim
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with an integer number n.
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void QwtDoubleRange::setValue(double x)
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setNewValue(x, false);
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\brief Specify range and step size
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\param vmin lower boundary of the interval
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\param vmax higher boundary of the interval
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\param vstep step width
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\param pageSize page size in steps
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\li A change of the range changes the value if it lies outside the
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new range. The current value
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will *not* be adjusted to the new step raster.
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\li vmax < vmin is allowed.
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\li If the step size is left out or set to zero, it will be
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set to 1/100 of the interval length.
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\li If the step size has an absurd value, it will be corrected
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void QwtDoubleRange::setRange(double vmin, double vmax, double vstep, int pageSize)
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bool rchg = ((d_maxValue != vmax) || (d_minValue != vmin));
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// look if the step width has an acceptable
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// value or otherwise change it.
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d_pageSize = qwtLim(pageSize,0,
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int(qwtAbs((d_maxValue - d_minValue) / d_step)));
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// If the value lies out of the range, it
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// will be changed. Note that it will not be adjusted to
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// the new step width.
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setNewValue(d_value, false);
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// call notifier after the step width has been
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\brief Change the step raster
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\param vstep new step width
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\warning The value will \e not be adjusted to the new step raster.
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void QwtDoubleRange::setStep(double vstep)
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double intv = d_maxValue - d_minValue;
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newStep = intv * DefaultRelStep;
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if ((intv > 0) && (vstep < 0) || (intv < 0) && (vstep > 0))
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if ( fabs(newStep) < fabs(MinRelStep * intv) )
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newStep = MinRelStep * intv;
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if (newStep != d_step)
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\brief Make the range periodic
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When the range is periodic, the value will be set to a point
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inside the interval such that
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\verbatim point = value + n * width \endverbatim
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if the user tries to set a new value which is outside the range.
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If the range is nonperiodic (the default), values outside the
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range will be clipped.
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\param tf true for a periodic range
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void QwtDoubleRange::setPeriodic(bool tf)
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\brief Increment the value by a specified number of steps
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\param nSteps Number of steps to increment
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\warning As a result of this operation, the new value will always be
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adjusted to the step raster.
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void QwtDoubleRange::incValue(int nSteps)
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setNewValue(d_value + double(nSteps) * d_step, true);
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\brief Increment the value by a specified number of pages
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\param nPages Number of pages to increment.
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A negative number decrements the value.
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\warning The Page size is specified in the constructor.
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void QwtDoubleRange::incPages(int nPages)
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setNewValue(d_value + double(nPages) * double(d_pageSize) * d_step, true);
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\brief Notify a change of value
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This virtual function is called whenever the value changes.
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The default implementation does nothing.
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void QwtDoubleRange::valueChange()
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\brief Notify a change of the range
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This virtual function is called whenever the range changes.
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The default implementation does nothing.
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void QwtDoubleRange::rangeChange()
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\brief Notify a change of the step size
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This virtual function is called whenever the step size changes.
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The default implementation does nothing.
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void QwtDoubleRange::stepChange()
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\return the step size
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\sa setStep(), setRange()
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double QwtDoubleRange::step() const
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return qwtAbs(d_step);
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\brief Returns the value of the second border of the range
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maxValue returns the value which has been specified
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as the second parameter in QwtDoubleRange::setRange.
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double QwtDoubleRange::maxValue() const
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\brief Returns the value at the first border of the range
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minValue returns the value which has been specified
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as the first parameter in setRange().
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double QwtDoubleRange::minValue() const
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\brief Returns true if the range is periodic
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bool QwtDoubleRange::periodic() const
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//! Returns the page size in steps.
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int QwtDoubleRange::pageSize() const
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//! Returns the current value.
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double QwtDoubleRange::value() const
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\brief Returns the exact value
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The exact value is the value which QwtDoubleRange::value would return
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if the value were not adjusted to the step raster. It differs from
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the current value only if QwtDoubleRange::fitValue or
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QwtDoubleRange::incValue have been used before. This function
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is intended for internal use in derived classes.
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double QwtDoubleRange::exactValue() const
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//! Returns the exact previous value
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double QwtDoubleRange::exactPrevValue() const
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return d_exactPrevValue;
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//! Returns the previous value
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double QwtDoubleRange::prevValue() const
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qwt/src/qwt_double_range.cpp
