QwtDoubleRange Class Reference
A class which controls a value within an interval. More...
#include <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 () |
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.
| QwtDoubleRange::~QwtDoubleRange | ( | ) | [virtual] |
Destroys the QwtDoubleRange.
Member Function Documentation
| double QwtDoubleRange::exactPrevValue | ( | ) | const [protected] |
Returns the exact previous value.
| 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 | ( | 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 with an integer number n.
new value := x + n * (max. value - min. value)
Reimplemented in QwtAbstractSlider.
| 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.
| 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.
| bool QwtDoubleRange::isValid | ( | ) | const |
Indicates if the value is valid.
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()
| int QwtDoubleRange::pageSize | ( | ) | const |
Returns the page size in steps.
| bool QwtDoubleRange::periodic | ( | ) | const |
Returns true if the range is periodic.
- See also:
- setPeriodic()
| double QwtDoubleRange::prevValue | ( | ) | const [protected] |
Returns the previous value.
| 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.
| 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
| 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.
| 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.
| void QwtDoubleRange::setValid | ( | bool | isValid | ) |
Set the value to be valid/invalid.
Reimplemented in QwtAbstractSlider.
| 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 with an integer number n.
new value := x + n * (max. value - min. value)
Reimplemented in QwtAbstractSlider, and QwtCounter.
| double QwtDoubleRange::step | ( | ) | const |
| 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.
| double QwtDoubleRange::value | ( | ) | const |
Returns the current value.
Reimplemented in QwtCounter.
| 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.
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