--- name: "QwtDoubleRange" section: "3" platform: "linux" package: "libqwt5-doc" version: "5.2.3-1" release: "Debian 10 (Buster)" platforms: ["linux"] url: "https://new.carta.tech/QwtDoubleRange" --- # QwtDoubleRange(3) ## NAME QwtDoubleRange - ## SYNOPSIS `#include ` 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 Generated automatically by Doxygen for Qwt User's Guide from the source code.