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# QwtDoubleRange Class Reference

Inheritance diagram for QwtDoubleRange:

[legend]
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 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.

Definition at line 31 of file qwt_double_range.h.

## Public Member Functions
| QwtDoubleRange ()
virtual | ~QwtDoubleRange ()
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

QwtDoubleRange::QwtDoubleRange | ( |  | ) |

| The range is initialized to [0.0, 100.0], the step size to 1.0, and the value to 0.0. Definition at line 21 of file qwt_double_range.cpp.

QwtDoubleRange::~QwtDoubleRange | ( |  | ) | `[virtual]`

| Destroys the QwtDoubleRange. Definition at line 36 of file qwt_double_range.cpp.

## Member Function Documentation

double QwtDoubleRange::exactPrevValue | ( |  | ) | const`[protected]`

| Returns the exact previous value. Definition at line 380 of file qwt_double_range.cpp. Referenced by QwtAbstractSlider::mouseMoveEvent().

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. Definition at line 374 of file qwt_double_range.cpp. Referenced by QwtAbstractSlider::mouseMoveEvent(), and QwtAbstractSlider::timerEvent().

void QwtDoubleRange::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 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. Definition at line 132 of file qwt_double_range.cpp. Referenced by QwtAbstractSlider::fitValue(), QwtAbstractSlider::mouseReleaseEvent(), QwtAbstractSlider::setPosition(), and QwtAbstractSlider::timerEvent().

void QwtDoubleRange::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. Definition at line 271 of file qwt_double_range.cpp. References isValid(). Referenced by QwtAbstractSlider::mouseReleaseEvent(), QwtAbstractSlider::timerEvent(), and QwtAbstractSlider::wheelEvent().

void QwtDoubleRange::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 QwtAbstractSlider. Definition at line 259 of file qwt_double_range.cpp. References isValid(). Referenced by QwtAbstractSlider::incValue(), QwtDial::keyPressEvent(), and QwtCounter::keyPressEvent().

bool QwtDoubleRange::isValid | ( |  | ) | const

| Indicates if the value is valid. Reimplemented in QwtAbstractSlider. Definition at line 51 of file qwt_double_range.cpp. Referenced by incPages(), incValue(), and QwtAbstractSlider::isValid().

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: QwtDoubleRange::setRange() Definition at line 326 of file qwt_double_range.cpp. Referenced by QwtDial::drawContents(), QwtWheel::drawWheel(), QwtWheel::getValue(), QwtDial::getValue(), QwtDial::keyPressEvent(), QwtCounter::keyPressEvent(), QwtCounter::maxVal(), QwtSlider::rangeChange(), QwtCounter::setMinValue(), QwtCounter::sizeHint(), and QwtDial::updateScale().

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: QwtDoubleRange::setRange() Definition at line 339 of file qwt_double_range.cpp. Referenced by QwtDial::drawContents(), QwtWheel::drawWheel(), QwtWheel::getValue(), QwtDial::getValue(), QwtDial::keyPressEvent(), QwtCounter::keyPressEvent(), QwtCounter::minVal(), QwtSlider::rangeChange(), QwtCounter::setMaxValue(), QwtCounter::sizeHint(), and QwtDial::updateScale().

int QwtDoubleRange::pageSize | ( |  | ) | const

| Returns the page size in steps. Definition at line 354 of file qwt_double_range.cpp. Referenced by QwtDial::keyPressEvent().

bool QwtDoubleRange::periodic | ( |  | ) | const

| Returns true if the range is periodic. See also: QwtDoubleRange::setPeriodic() Definition at line 348 of file qwt_double_range.cpp. Referenced by QwtDial::wrapping().

double QwtDoubleRange::prevValue | ( |  | ) | const`[protected]`

| Returns the previous value. Definition at line 386 of file qwt_double_range.cpp. Referenced by QwtDial::keyPressEvent(), QwtAbstractSlider::mouseMoveEvent(), and QwtAbstractSlider::wheelEvent().

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. Definition at line 294 of file qwt_double_range.cpp. Referenced by QwtSlider::rangeChange(), and setRange().

void QwtDoubleRange::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
Definition at line 248 of file qwt_double_range.cpp. Referenced by QwtDial::setWrapping().

void QwtDoubleRange::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. Definition at line 169 of file qwt_double_range.cpp. References rangeChange(), and setStep(). Referenced by QwtCounter::setMaxValue(), and QwtCounter::setMinValue().

void QwtDoubleRange::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. Definition at line 208 of file qwt_double_range.cpp. References stepChange(). Referenced by setRange(), and QwtCounter::setStep().

void QwtDoubleRange::setValid | ( | bool |  | ) |

| Set the value to be valid/invalid. Reimplemented in QwtAbstractSlider. Definition at line 41 of file qwt_double_range.cpp. References valueChange(). Referenced by QwtAbstractSlider::setValid().

void QwtDoubleRange::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 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. Definition at line 147 of file qwt_double_range.cpp. Referenced by QwtCounter::setValue(), and QwtAbstractSlider::setValue().

double QwtDoubleRange::step | ( |  | ) | const

| Returns: the step size See also: QwtDoubleRange::setStep, QwtDoubleRange::setRange Reimplemented in QwtCounter. Definition at line 313 of file qwt_double_range.cpp. Referenced by QwtAbstractSlider::mouseReleaseEvent(), QwtCounter::step(), and QwtAbstractSlider::timerEvent().

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. Definition at line 305 of file qwt_double_range.cpp. Referenced by setStep().

double QwtDoubleRange::value | ( |  | ) | const

| Returns the current value. Reimplemented in QwtCounter. Definition at line 360 of file qwt_double_range.cpp. Referenced by QwtDial::drawContents(), QwtAnalogClock::drawNeedle(), QwtCompass::drawScaleContents(), QwtSlider::drawSlider(), QwtWheel::drawWheel(), QwtDial::getValue(), QwtAbstractSlider::mouseMoveEvent(), QwtAbstractSlider::mousePressEvent(), QwtAbstractSlider::mouseReleaseEvent(), QwtAbstractSlider::timerEvent(), QwtCounter::value(), QwtAbstractSlider::valueChange(), and QwtAbstractSlider::wheelEvent().

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. Definition at line 283 of file qwt_double_range.cpp. Referenced by setValid().