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QwtDblRange Class Reference

Inheritance diagram for QwtDblRange:

QwtCounter QwtSliderBase QwtDial QwtKnob QwtSlider QwtWheel QwtAnalogClock QwtCompass List of all members.

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 QwtDblRange::setValue), or it can be fitted into a step raster (see QwtDblRange::fitValue and QwtDblRange::incValue).

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


Public Member Functions

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

Protected Member Functions

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


Constructor & Destructor Documentation

QwtDblRange::QwtDblRange  ) 
 

The range is initialized to [0.0, 100.0], the step size to 1.0, and the value to 0.0.

QwtDblRange::~QwtDblRange  )  [virtual]
 

Destroys the QwtDblRange.


Member Function Documentation

double QwtDblRange::exactPrevValue  )  const [protected]
 

Returns the exact previous value.

double QwtDblRange::exactValue  )  const [protected]
 

Returns the exact value.

The exact value is the value which QwtDblRange::value would return if the value were not adjusted to the step raster. It differs from the current value only if QwtDblRange::fitValue or QwtDblRange::incValue have been used before. This function is intended for internal use in derived classes.

void QwtDblRange::fitValue double  x  )  [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 QwtDblRange::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 QwtSliderBase.

void QwtDblRange::incPages int  nPages  )  [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 QwtDblRange::incValue int  nSteps  )  [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 QwtSliderBase.

bool QwtDblRange::isValid  )  const
 

Indicates if the value is valid.

Reimplemented in QwtSliderBase.

double QwtDblRange::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 QwtDblRange::setRange.

See also:
QwtDblRange::setRange()

double QwtDblRange::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:
QwtDblRange::setRange()

int QwtDblRange::pageSize  )  const
 

Returns the page size in steps.

bool QwtDblRange::periodic  )  const
 

Returns TRUE if the range is periodic.

See also:
QwtDblRange::setPeriodic()

double QwtDblRange::prevValue  )  const [protected]
 

Returns the previous value.

void QwtDblRange::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 QwtDblRange::setPeriodic bool  tf  ) 
 

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 

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 QwtDblRange::setRange double  vmin,
double  vmax,
double  vstep = 0.0,
int  pageSize = 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 QwtDblRange::setStep double  vstep  ) 
 

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 QwtDblRange::setValid bool   ) 
 

Set the value to be valid/invalid.

Reimplemented in QwtSliderBase.

void QwtDblRange::setValue double  x  )  [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 QwtDblRange::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 QwtSliderBase.

double QwtDblRange::step  )  const
 

Returns:
the step size
See also:
QwtDblRange::setStep, QwtDblRange::setRange

Reimplemented in QwtCounter.

void QwtDblRange::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 QwtDblRange::value  )  const
 

Returns the current value.

Reimplemented in QwtCounter.

void QwtDblRange::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, QwtSliderBase, QwtSlider, and QwtWheel.


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