QwtAbstractScale - An abstract base class for widgets having a scale.

NAME

QwtAbstractScale − An abstract base class for widgets having a scale.

SYNOPSIS

#include <qwt_abstract_scale.h>

Inherits QWidget.

Inherited by QwtAbstractSlider, and QwtThermo.

Public Member Functions

QwtAbstractScale (QWidget *parent=NULL)
virtual ˜QwtAbstractScale ()
Destructor.
void setScale (double lowerBound, double upperBound)
Specify a scale.
void setScale (const QwtInterval &)
Specify a scale.
void setScale (const QwtScaleDiv &)
Specify a scale.
const QwtScaleDiv & scaleDiv () const
void setLowerBound (double value)
double lowerBound () const
void setUpperBound (double value)
double upperBound () const
void setScaleStepSize (double stepSize)
Set the step size used for calculating a scale division.
double scaleStepSize () const
void setScaleMaxMajor (int ticks)
Set the maximum number of major tick intervals.
int scaleMaxMinor () const
void setScaleMaxMinor (int ticks)
Set the maximum number of minor tick intervals.
int scaleMaxMajor () const
void setScaleEngine (QwtScaleEngine *)
Set a scale engine.
const QwtScaleEngine * scaleEngine () const
QwtScaleEngine * scaleEngine ()
int transform (double) const
double invTransform (int) const
bool isInverted () const
double minimum () const
double maximum () const
const QwtScaleMap & scaleMap () const

Protected Member Functions

virtual void changeEvent (QEvent *) override
void rescale (double lowerBound, double upperBound, double stepSize)
void setAbstractScaleDraw (QwtAbstractScaleDraw *)
Set a scale draw.
const QwtAbstractScaleDraw * abstractScaleDraw () const
QwtAbstractScaleDraw * abstractScaleDraw ()
void updateScaleDraw ()
virtual void scaleChange ()
Notify changed scale.

Detailed Description

An abstract base class for widgets having a scale.

The scale of an QwtAbstractScale is determined by a QwtScaleDiv definition, that contains the boundaries and the ticks of the scale. The scale is painted using a QwtScaleDraw object.

The scale division might be assigned explicitly - but usually it is calculated from the boundaries using a QwtScaleEngine.

The scale engine also decides the type of transformation of the scale ( linear, logarithmic ... ).

Definition at line 36 of file qwt_abstract_scale.h.

Constructor & Destructor Documentation

QwtAbstractScale::QwtAbstractScale (QWidget * parent = NULL) [explicit]

Constructor

Parameters

parent Parent widget

Creates a default QwtScaleDraw and a QwtLinearScaleEngine. The initial scale boundaries are set to [ 0.0, 100.0 ]

The scaleStepSize() is initialized to 0.0, scaleMaxMajor() to 5 and scaleMaxMajor to 3.

Definition at line 57 of file qwt_abstract_scale.cpp.

QwtAbstractScale::˜QwtAbstractScale () [virtual]

Destructor.

Definition at line 65 of file qwt_abstract_scale.cpp.

Member Function Documentation

QwtAbstractScaleDraw * QwtAbstractScale::abstractScaleDraw () [protected]

Returns

Scale draw

See also

setAbstractScaleDraw()

Definition at line 293 of file qwt_abstract_scale.cpp.

const QwtAbstractScaleDraw * QwtAbstractScale::abstractScaleDraw () const[protected]

Returns

Scale draw

See also

setAbstractScaleDraw()

Definition at line 302 of file qwt_abstract_scale.cpp.

void QwtAbstractScale::changeEvent (QEvent * event) [override],[protected], [virtual]

Change Event handler

Parameters

event Change event

Invalidates internal caches if necessary

Reimplemented in QwtDial, QwtKnob, QwtSlider, and QwtThermo.

Definition at line 453 of file qwt_abstract_scale.cpp.

double QwtAbstractScale::invTransform (int value) const

Translate a widget coordinate into a scale value

Parameters

value Widget coordinate

Returns

Corresponding scale coordinate for value

See also

scaleMap(), transform()

Definition at line 381 of file qwt_abstract_scale.cpp.

bool QwtAbstractScale::isInverted () const

Returns

True, when the scale is increasing in opposite direction to the widget coordinates

Definition at line 390 of file qwt_abstract_scale.cpp.

double QwtAbstractScale::lowerBound () const

Returns

Lower bound of the scale

See also

setLowerBound(), setScale(), upperBound()

Definition at line 88 of file qwt_abstract_scale.cpp.

double QwtAbstractScale::maximum () const

Returns

The boundary with the larger value

See also

minimum(), lowerBound(), upperBound()

Definition at line 409 of file qwt_abstract_scale.cpp.

double QwtAbstractScale::minimum () const

Returns

The boundary with the smaller value

See also

maximum(), lowerBound(), upperBound()

Definition at line 399 of file qwt_abstract_scale.cpp.

void QwtAbstractScale::rescale (double lowerBound, double upperBound,double stepSize) [protected]

Recalculate the scale division and update the scale.

Parameters

lowerBound Lower limit of the scale interval
upperBound Upper limit of the scale interval
stepSize Major step size

See also

scaleChange()

Definition at line 429 of file qwt_abstract_scale.cpp.

void QwtAbstractScale::scaleChange () [protected], [virtual]

Notify changed scale.

Reimplemented in QwtAbstractSlider, QwtDial, QwtSlider, and QwtThermo.

Definition at line 416 of file qwt_abstract_scale.cpp.

const QwtScaleDiv & QwtAbstractScale::scaleDiv () const

Returns

Scale boundaries and positions of the ticks

The scale division might have been assigned explicitly or calculated implicitly by rescale().

Definition at line 349 of file qwt_abstract_scale.cpp.

QwtScaleEngine * QwtAbstractScale::scaleEngine ()

Returns

Scale engine

See also

setScaleEngine()

Definition at line 338 of file qwt_abstract_scale.cpp.

const QwtScaleEngine * QwtAbstractScale::scaleEngine () const

Returns

Scale engine

See also

setScaleEngine()

Definition at line 329 of file qwt_abstract_scale.cpp.

const QwtScaleMap & QwtAbstractScale::scaleMap () const

Returns

Map to translate between scale and widget coordinates

Definition at line 357 of file qwt_abstract_scale.cpp.

int QwtAbstractScale::scaleMaxMajor () const

Returns

Maximal number of major tick intervals

See also

setScaleMaxMajor(), scaleMaxMinor()

Definition at line 202 of file qwt_abstract_scale.cpp.

int QwtAbstractScale::scaleMaxMinor () const

Returns

Maximal number of minor tick intervals

See also

setScaleMaxMinor(), scaleMaxMajor()

Definition at line 232 of file qwt_abstract_scale.cpp.

double QwtAbstractScale::scaleStepSize () const

Returns

Hint for the step size of the scale

See also

setScaleStepSize(), QwtScaleEngine::divideScale()

Definition at line 264 of file qwt_abstract_scale.cpp.

void QwtAbstractScale::setAbstractScaleDraw (QwtAbstractScaleDraw *scaleDraw) [protected]

Set a scale draw. scaleDraw has to be created with new and will be deleted in the destructor or the next call of setAbstractScaleDraw().

See also

abstractScaleDraw()

Definition at line 277 of file qwt_abstract_scale.cpp.

void QwtAbstractScale::setLowerBound (double value)

Set the lower bound of the scale

Parameters

value Lower bound

See also

lowerBound(), setScale(), setUpperBound()

Note

For inverted scales the lower bound is greater than the upper bound

Definition at line 79 of file qwt_abstract_scale.cpp.

void QwtAbstractScale::setScale (const QwtInterval & interval)

Specify a scale. Define a scale by an interval

The ticks are calculated using scaleMaxMinor(), scaleMaxMajor() and scaleStepSize().

Parameters

interval Interval

Definition at line 145 of file qwt_abstract_scale.cpp.

void QwtAbstractScale::setScale (const QwtScaleDiv & scaleDiv)

Specify a scale. scaleMaxMinor(), scaleMaxMajor() and scaleStepSize() and have no effect.

Parameters

scaleDiv Scale division

See also

setAutoScale()

Definition at line 158 of file qwt_abstract_scale.cpp.

void QwtAbstractScale::setScale (double lowerBound, double upperBound)

Specify a scale. Define a scale by an interval

The ticks are calculated using scaleMaxMinor(), scaleMaxMajor() and scaleStepSize().

Parameters

lowerBound lower limit of the scale interval
upperBound upper limit of the scale interval

Note

For inverted scales the lower bound is greater than the upper bound

Definition at line 130 of file qwt_abstract_scale.cpp.

void QwtAbstractScale::setScaleEngine (QwtScaleEngine * scaleEngine)

Set a scale engine. The scale engine is responsible for calculating the scale division and provides a transformation between scale and widget coordinates.

scaleEngine has to be created with new and will be deleted in the destructor or the next call of setScaleEngine.

Definition at line 316 of file qwt_abstract_scale.cpp.

void QwtAbstractScale::setScaleMaxMajor (int ticks)

Set the maximum number of major tick intervals. The scale’s major ticks are calculated automatically such that the number of major intervals does not exceed ticks.

The default value is 5.

Parameters

ticks Maximal number of major ticks.

See also

scaleMaxMajor(), setScaleMaxMinor(), setScaleStepSize(), QwtScaleEngine::divideInterval()

Definition at line 189 of file qwt_abstract_scale.cpp.

void QwtAbstractScale::setScaleMaxMinor (int ticks)

Set the maximum number of minor tick intervals. The scale’s minor ticks are calculated automatically such that the number of minor intervals does not exceed ticks. The default value is 3.

Parameters

ticks Maximal number of minor ticks.

See also

scaleMaxMajor(), setScaleMaxMinor(), setScaleStepSize(), QwtScaleEngine::divideInterval()

Definition at line 219 of file qwt_abstract_scale.cpp.

void QwtAbstractScale::setScaleStepSize (double stepSize)

Set the step size used for calculating a scale division. The step size is hint for calculating the intervals for the major ticks of the scale. A value of 0.0 is interpreted as no hint.

Parameters

stepSize Hint for the step size of the scale

See also

scaleStepSize(), QwtScaleEngine::divideScale()

Note

Position and distance between the major ticks also depends on scaleMaxMajor().

Definition at line 251 of file qwt_abstract_scale.cpp.

void QwtAbstractScale::setUpperBound (double value)

Set the upper bound of the scale

Parameters

value Upper bound

See also

upperBound(), setScale(), setLowerBound()

Note

For inverted scales the lower bound is greater than the upper bound

Definition at line 102 of file qwt_abstract_scale.cpp.

int QwtAbstractScale::transform (double value) const

Translate a scale value into a widget coordinate

Parameters

value Scale value

Returns

Corresponding widget coordinate for value

See also

scaleMap(), invTransform()

Definition at line 369 of file qwt_abstract_scale.cpp.

void QwtAbstractScale::updateScaleDraw () [protected]

Recalculate ticks and scale boundaries.

Definition at line 466 of file qwt_abstract_scale.cpp.

double QwtAbstractScale::upperBound () const

Returns

Upper bound of the scale

See also

setUpperBound(), setScale(), lowerBound()

Definition at line 111 of file qwt_abstract_scale.cpp.

Author

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Updated 2026-06-01 - jenkler.se | uex.se