QwtDoubleRange(3) Qwt User's Guide QwtDoubleRange(3)NAMEQwtDoubleRange-
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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Version 5.2.3 Tue Nov 20 2012 QwtDoubleRange(3)
