Provided by: libqwt5-doc_5.2.3-1_all 
NAME
QwtDoubleRange -
SYNOPSIS
#include <qwt_double_range.h>
Inherited by QwtAbstractSlider, and QwtCounter.
Public Member Functions
QwtDoubleRange ()
virtual ~QwtDoubleRange ()
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
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
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.
Member Function Documentation
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.
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()
bool QwtDoubleRange::periodic () const
Returns true if the range is periodic. See also:
setPeriodic()
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 QwtDial, QwtCounter, 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:
• 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.
• vmax < vmin is allowed.
• If the step size is left out or set to zero, it will be set to 1/100 of the interval length.
• 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::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 QwtCounter, and QwtAbstractSlider.
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.
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 QwtDial, QwtAbstractSlider, QwtSlider, and QwtWheel.
Author
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