QwtDoubleRange(3)						 Qwt User's Guide						 QwtDoubleRange(3)

NAME

       QwtDoubleRange -

       A class which controls a value within an interval.

SYNOPSIS

       #include <qwt_double_range.h>

       Inherited by QwtAbstractSlider, and QwtCounter.

   Public Member Functions
       virtual void fitValue (double)
       virtual void incPages (int)
       virtual void incValue (int)
       bool isValid () const
       double maxValue () const
       double minValue () const
       int pageSize () const
       bool periodic () const
       QwtDoubleRange ()
       void setPeriodic (bool tf)
       void setRange (double vmin, double vmax, double vstep=0.0, int pagesize=1)
       void setStep (double)
       void setValid (bool)
       virtual void setValue (double)
       double step () const
       double value () const
       virtual ~QwtDoubleRange ()

   Protected Member Functions
       double exactPrevValue () const
       double exactValue () const
       double prevValue () const
       virtual void rangeChange ()
       virtual void stepChange ()
       virtual void valueChange ()

Detailed Description
       A class which controls a value within an interval.

       This class is useful as a base class or a member for sliders. It represents an interval of type double within which a value can be moved.
       The value can be either an arbitrary point inside the interval (see QwtDoubleRange::setValue), or it can be fitted into a step raster (see
       QwtDoubleRange::fitValue and QwtDoubleRange::incValue).

       As a special case, a QwtDoubleRange can be periodic, which means that a value outside the interval will be mapped to a value inside the
       interval when QwtDoubleRange::setValue(), QwtDoubleRange::fitValue(), QwtDoubleRange::incValue() or QwtDoubleRange::incPages() are called.

Constructor &; Destructor Documentation
   QwtDoubleRange::QwtDoubleRange () The range is initialized to [0.0, 100.0], the step size to 1.0, and the value to 0.0.
   QwtDoubleRange::~QwtDoubleRange () [virtual]
       Destroys the QwtDoubleRange.

Member Function Documentation
   double QwtDoubleRange::exactPrevValue () const [protected]
       Returns the exact previous value.

   double QwtDoubleRange::exactValue () const [protected]
       Returns the exact value. The exact value is the value which QwtDoubleRange::value would return if the value were not adjusted to the step
       raster. It differs from the current value only if QwtDoubleRange::fitValue or QwtDoubleRange::incValue have been used before. This function
       is intended for internal use in derived classes.

   void QwtDoubleRange::fitValue (doublex) [virtual]
       Adjust the value to the closest point in the step raster. Parameters:
	   x value

       Warning:
	   The value is clipped when it lies outside the range. When the range is QwtDoubleRange::periodic, it will be mapped to a point in the
	   interval such that

	   new value := x + n * (max. value - min. value)

	    with an integer number n.

       Reimplemented in QwtAbstractSlider.

   void QwtDoubleRange::incPages (intnPages) [virtual]
       Increment the value by a specified number of pages. Parameters:
	   nPages Number of pages to increment. A negative number decrements the value.

       Warning:
	   The Page size is specified in the constructor.

   void QwtDoubleRange::incValue (intnSteps) [virtual]
       Increment the value by a specified number of steps. Parameters:
	   nSteps Number of steps to increment

       Warning:
	   As a result of this operation, the new value will always be adjusted to the step raster.

       Reimplemented in QwtAbstractSlider.

   bool QwtDoubleRange::isValid () const
       Indicates if the value is valid.

       Reimplemented in QwtAbstractSlider.

   double QwtDoubleRange::maxValue () const
       Returns the value of the second border of the range. maxValue returns the value which has been specified as the second parameter in
       QwtDoubleRange::setRange.

       See also:
	   setRange()

   double QwtDoubleRange::minValue () const
       Returns the value at the first border of the range. minValue returns the value which has been specified as the first parameter in
       setRange().

       See also:
	   setRange()

   int QwtDoubleRange::pageSize () const
       Returns the page size in steps.

   bool QwtDoubleRange::periodic () const
       Returns true if the range is periodic. See also:
	   setPeriodic()

   double QwtDoubleRange::prevValue () const [protected]
       Returns the previous value.

   void QwtDoubleRange::rangeChange () [protected, virtual]
       Notify a change of the range. This virtual function is called whenever the range changes. The default implementation does nothing.

       Reimplemented in QwtCounter, QwtDial, and QwtSlider.

   void QwtDoubleRange::setPeriodic (booltf)
       Make the range periodic. When the range is periodic, the value will be set to a point inside the interval such that

       point = value + n * width .fi

       if the user tries to set a new value which is outside the range. If the range is nonperiodic (the default), values outside the range will be clipped.

       Parameters:
	   tf true for a periodic range

   void QwtDoubleRange::setRange (doublevmin, doublevmax, doublevstep = 0.0, intpageSize = 1)
       Specify range and step size. Parameters:
	   vmin lower boundary of the interval
	   vmax higher boundary of the interval
	   vstep step width
	   pageSize page size in steps

       Warning:
	   o A change of the range changes the value if it lies outside the new range. The current value will *not* be adjusted to the new step
	     raster.
	   o vmax < vmin is allowed.
	   o If the step size is left out or set to zero, it will be set to 1/100 of the interval length.
	   o If the step size has an absurd value, it will be corrected to a better one.
   void QwtDoubleRange::setStep (doublevstep)
       Change the step raster. Parameters:
	   vstep new step width
       Warning:
	   The value will not be adjusted to the new step raster.
       Reimplemented in QwtCounter.
   void QwtDoubleRange::setValid (boolisValid)
       Set the value to be valid/invalid.
       Reimplemented in QwtAbstractSlider.
   void QwtDoubleRange::setValue (doublex) [virtual]
       Set a new value without adjusting to the step raster. Parameters:
	   x new value
       Warning:
	   The value is clipped when it lies outside the range. When the range is QwtDoubleRange::periodic, it will be mapped to a point in the
	   interval such that
	   new value := x + n * (max. value - min. value)
	    with an integer number n.
       Reimplemented in QwtAbstractSlider, and QwtCounter.
   double QwtDoubleRange::step () const Returns:
	   the step size
       See also:
	   setStep(), setRange()
       Reimplemented in QwtCounter.
   void QwtDoubleRange::stepChange () [protected, virtual]
       Notify a change of the step size. This virtual function is called whenever the step size changes. The default implementation does nothing.
   double QwtDoubleRange::value () const
       Returns the current value.
       Reimplemented in QwtCounter.
   void QwtDoubleRange::valueChange () [protected, virtual]
       Notify a change of value. This virtual function is called whenever the value changes. The default implementation does nothing.
       Reimplemented in QwtAbstractSlider, QwtDial, QwtSlider, and QwtWheel.

Author
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Version 5.2.2							  Mon Aug 1 2011						 QwtDoubleRange(3)