The Knob Widget. More...

#include <qwt_knob.h>

Inheritance diagram for QwtKnob:

Classes
class	PrivateData

Public Types
enum	KnobStyle { Flat , Raised , Sunken , Styled }
	Style of the knob surface. More...

enum	MarkerStyle { NoMarker = -1 , Tick , Triangle , Dot , Nub , Notch }
	Marker type. More...

Public Member Functions
	QwtKnob (QWidget *parent=nullptr)
	Constructor.

	~QwtKnob () override
	Destructor.

void	setAlignment (Qt::Alignment)
	Set alignment of the knob inside contentsRect()

Qt::Alignment	alignment () const
	Return alignment of the knob.

void	setKnobWidth (int)
	Set the knob's width (diameter)

int	knobWidth () const
	Return the knob's width.

void	setNumTurns (int)
	Set the number of turns for the knob.

int	numTurns () const
	Return the number of turns.

void	setTotalAngle (double angle)
	Set the total angle which the knob can be turned.

double	totalAngle () const
	Return the total angle.

void	setKnobStyle (KnobStyle)
	Set the knob style.

KnobStyle	knobStyle () const
	Return the knob style.

void	setBorderWidth (int)
	Set the border width.

int	borderWidth () const
	Return the border width.

void	setMarkerStyle (MarkerStyle)
	Set the marker style.

MarkerStyle	markerStyle () const
	Return the marker style.

void	setMarkerSize (int)
	Set the marker size.

int	markerSize () const
	Return the marker size.

virtual QSize	sizeHint () const override
	Return size hint.

virtual QSize	minimumSizeHint () const override
	Return minimum size hint.

void	setScaleDraw (QwtRoundScaleDraw *)
	Set the scale draw.

const QwtRoundScaleDraw *	scaleDraw () const
	Return the scale draw (const version)

QwtRoundScaleDraw *	scaleDraw ()
	Return the scale draw (non-const version)

QRect	knobRect () const
	Return the bounding rectangle of the knob.

Public Member Functions inherited from QwtAbstractSlider
	QwtAbstractSlider (QWidget *parent=nullptr)
	Constructor for QwtAbstractSlider (English only)

	~QwtAbstractSlider () override
	Destructor for QwtAbstractSlider (English only)

void	setValid (bool)
	Set whether the slider is valid (English only)

bool	isValid () const
	Return whether the slider is valid (English only)

double	value () const
	Return the current value (English only)

void	setWrapping (bool)
	Set whether wrapping is enabled (English only)

bool	wrapping () const
	Return whether wrapping is enabled (English only)

void	setTotalSteps (uint)
	Set the total number of steps (English only)

uint	totalSteps () const
	Return the total number of steps (English only)

void	setSingleSteps (uint)
	Set the number of single steps (English only)

uint	singleSteps () const
	Return the number of single steps (English only)

void	setPageSteps (uint)
	Set the number of page steps (English only)

uint	pageSteps () const
	Return the number of page steps (English only)

void	setStepAlignment (bool)
	Set whether step alignment is enabled (English only)

bool	stepAlignment () const
	Return whether step alignment is enabled (English only)

void	setTracking (bool)
	Set whether tracking is enabled (English only)

bool	isTracking () const
	Return whether tracking is enabled (English only)

void	setReadOnly (bool)
	Set whether the slider is read-only (English only)

bool	isReadOnly () const
	Return whether the slider is read-only (English only)

void	setInvertedControls (bool)
	Set whether controls are inverted (English only)

bool	invertedControls () const
	Return whether controls are inverted (English only)

Public Member Functions inherited from QwtAbstractScale
	QwtAbstractScale (QWidget *parent=nullptr)
	Constructor for QwtAbstractScale.

void	setScale (double lowerBound, double upperBound)
	Specify a scale by interval bounds.

void	setScale (const QwtInterval &)
	Specify a scale by interval.

void	setScale (const QwtScaleDiv &)
	Specify a scale by scale division.

const QwtScaleDiv &	scaleDiv () const
	Return the scale division.

void	setLowerBound (double value)
	Set the lower bound of the scale.

double	lowerBound () const
	Return the lower bound of the scale.

void	setUpperBound (double value)
	Set the upper bound of the scale.

double	upperBound () const
	Return the upper bound of the scale.

void	setScaleStepSize (double stepSize)
	Set the step size used for calculating scale division.

double	scaleStepSize () const
	Return the step size hint.

void	setScaleMaxMajor (int ticks)
	Set the maximum number of major tick intervals.

int	scaleMaxMinor () const
	Return the maximum number of minor tick intervals.

void	setScaleMaxMinor (int ticks)
	Set the maximum number of minor tick intervals.

int	scaleMaxMajor () const
	Return the maximum number of major tick intervals.

void	setScaleEngine (QwtScaleEngine *)
	Set the scale engine.

const QwtScaleEngine *	scaleEngine () const
	Return the scale engine (const version)

QwtScaleEngine *	scaleEngine ()
	Return the scale engine (non-const version)

int	transform (double) const
	Transform a scale value to widget coordinates.

double	invTransform (int) const
	Transform a widget coordinate to scale value.

bool	isInverted () const
	Check if scale is inverted.

double	minimum () const
	Return the minimum boundary.

double	maximum () const
	Return the maximum boundary.

const QwtScaleMap &	scaleMap () const
	Return the scale map.

Protected Member Functions
virtual void	paintEvent (QPaintEvent *) override
	Repaint the knob.

virtual void	changeEvent (QEvent *) override
	Handle QEvent::StyleChange and QEvent::FontChange;.

virtual void	drawKnob (QPainter *, const QRectF &) const
	Draw the knob.

virtual void	drawFocusIndicator (QPainter *) const
	Draw the focus indicator.

virtual void	drawMarker (QPainter *, const QRectF &, double angle) const
	Draw the marker at the knob's front.

virtual double	scrolledTo (const QPoint &) const override
	Determine the value for a new position of the mouse.

virtual bool	isScrollPosition (const QPoint &) const override
	Determine what to do when the user presses a mouse button.

Protected Member Functions inherited from QwtAbstractSlider
virtual void	mousePressEvent (QMouseEvent *) override
	Handle mouse press events (English only)

virtual void	mouseReleaseEvent (QMouseEvent *) override
	Handle mouse release events (English only)

virtual void	mouseMoveEvent (QMouseEvent *) override
	Handle mouse move events (English only)

virtual void	keyPressEvent (QKeyEvent *) override
	Handle key press events (English only)

virtual void	wheelEvent (QWheelEvent *) override
	Handle wheel events (English only)

void	incrementValue (int stepCount)
	Increment the value by a number of steps (English only)

virtual void	scaleChange () override
	Handle scale changes (English only)

virtual void	sliderChange ()
	Handle slider changes (English only)

double	incrementedValue (double value, int stepCount) const
	Calculate incremented value (English only)

Protected Member Functions inherited from QwtAbstractScale
void	rescale (double lowerBound, double upperBound, double stepSize)
	Recalculate scale and update scale draw (English only)

void	setAbstractScaleDraw (QwtAbstractScaleDraw *)
	Set the scale draw object (English only)

const QwtAbstractScaleDraw *	abstractScaleDraw () const
	Return the scale draw (const version) (English only)

QwtAbstractScaleDraw *	abstractScaleDraw ()
	Return the scale draw (non-const version) (English only)

void	updateScaleDraw ()
	Update the scale draw (English only)

Properties
KnobStyle	knobStyle

int	knobWidth

Qt::Alignment	alignment

double	totalAngle

int	numTurns

MarkerStyle	markerStyle

int	markerSize

int	borderWidth

Properties inherited from QwtAbstractSlider
double	value

uint	totalSteps

uint	singleSteps

uint	pageSteps

bool	stepAlignment

bool	readOnly

bool	tracking

bool	wrapping

bool	invertedControls

Properties inherited from QwtAbstractScale
double	lowerBound

double	upperBound

int	scaleMaxMajor

int	scaleMaxMinor

double	scaleStepSize

Additional Inherited Members
Public Slots inherited from QwtAbstractSlider
void	setValue (double value)
	Set the slider value (English only)

Signals inherited from QwtAbstractSlider
void	valueChanged (double value)
	Notify a change of value.

void	sliderPressed ()
	Signal emitted when the user presses the movable part of the slider.

void	sliderReleased ()
	Signal emitted when the user releases the movable part of the slider.

void	sliderMoved (double value)
	Signal emitted when the user moves the slider with the mouse.

Detailed Description

The Knob Widget.

The QwtKnob widget imitates look and behavior of a volume knob on a radio. It looks similar to QDial - not to QwtDial. The value range of a knob might be divided into several turns. The layout of the knob depends on the knobWidth():

width > 0: The diameter of the knob is fixed and the knob is aligned according to the alignment() flags inside of the contentsRect().
width <= 0: The knob is extended to the minimum of width/height of the contentsRect() and aligned in the other direction according to alignment(). Setting a fixed knobWidth() is helpful to align several knobs with different scale labels.

Member Enumeration Documentation

◆ KnobStyle

enum QwtKnob::KnobStyle

Style of the knob surface.

Depending on the KnobStyle the surface of the knob is filled from the brushes of the widget palette().

See also: setKnobStyle(), knobStyle()

Enumerator
Flat	Fill the knob with a brush from QPalette::Button.
Raised	Build a gradient from QPalette::Midlight and QPalette::Button.
Sunken	Build a gradient from QPalette::Midlight, QPalette::Button and QPalette::Midlight.
Styled	Build a radial gradient from QPalette::Button like QDial in various Qt styles.

◆ MarkerStyle

enum QwtKnob::MarkerStyle

Marker type.

The marker indicates the current value on the knob. The default setting is a Notch marker.

See also: setMarkerStyle(), setMarkerSize()

Enumerator
NoMarker	Don't paint any marker.
Tick	Paint a single tick in QPalette::ButtonText color.
Triangle	Paint a triangle in QPalette::ButtonText color.
Dot	Paint a circle in QPalette::ButtonText color.
Nub	Draw a raised ellipse with a gradient from QPalette::Light and QPalette::Mid.
Notch	Draw a sunken ellipse with a gradient from QPalette::Light and QPalette::Mid.

Constructor & Destructor Documentation

◆ QwtKnob()

QwtKnob::QwtKnob ( QWidget * parent = nullptr )

explicit

Constructor.

Construct a knob with an angle of 270°. The style is QwtKnob::Raised and the marker style is QwtKnob::Notch. The width of the knob is set to 50 pixels.

Parameters

parent Parent widget

See also: setTotalAngle()

Member Function Documentation

◆ alignment()

Qt::Alignment QwtKnob::alignment ( ) const

Return alignment of the knob.

Return alignment of the knob inside contentsRect()

Returns: Alignment flags

See also: setAlignment(), knobWidth(), knobRect()

◆ changeEvent()

void QwtKnob::changeEvent ( QEvent * event )

overrideprotectedvirtual

Handle QEvent::StyleChange and QEvent::FontChange;.

Parameters

event Change event

Reimplemented from QwtAbstractScale.

◆ drawFocusIndicator()

void QwtKnob::drawFocusIndicator ( QPainter * painter ) const

protectedvirtual

Draw the focus indicator.

Parameters

painter Painter

◆ drawKnob()

void QwtKnob::drawKnob	(	QPainter *	painter,
		const QRectF &	knobRect
	)		const

protectedvirtual

Draw the knob.

Parameters

painter	painter
knobRect	Bounding rectangle of the knob (without scale)

◆ drawMarker()

void QwtKnob::drawMarker	(	QPainter *	painter,
		const QRectF &	rect,
		double	angle
	)		const

protectedvirtual

Draw the marker at the knob's front.

Parameters

painter	Painter
rect	Bounding rectangle of the knob without scale
angle	Angle of the marker in degrees ( clockwise, 0 at the 12 o'clock position )

◆ isScrollPosition()

bool QwtKnob::isScrollPosition ( const QPoint & pos ) const

overrideprotectedvirtual

Determine what to do when the user presses a mouse button.

Parameters

pos	Mouse position

Return values

True,when pos is inside the circle of the knob.

See also: scrolledTo()

Implements QwtAbstractSlider.

◆ knobRect()

QRect QwtKnob::knobRect ( ) const

Return the bounding rectangle of the knob.

Calculate the bounding rectangle of the knob without the scale.

Returns: Bounding rectangle of the knob

See also: knobWidth(), alignment(), QWidget::contentsRect()

◆ knobStyle()

QwtKnob::KnobStyle QwtKnob::knobStyle ( ) const

Return the knob style.

Returns: Knob type

See also: setKnobStyle(), setBorderWidth()

◆ knobWidth()

int QwtKnob::knobWidth ( ) const

Return the knob's width.

Return the width of the knob.

◆ markerSize()

int QwtKnob::markerSize ( ) const

Return the marker size.

Returns: Marker size

See also: setMarkerSize()

◆ markerStyle()

QwtKnob::MarkerStyle QwtKnob::markerStyle ( ) const

Return the marker style.

Returns: Marker type of the knob

See also: setMarkerStyle(), setMarkerSize()

◆ minimumSizeHint()

QSize QwtKnob::minimumSizeHint ( ) const

overridevirtual

Return minimum size hint.

Return the minimum size hint.

Returns: Minimum size hint

See also: sizeHint()

◆ numTurns()

int QwtKnob::numTurns ( ) const

Return the number of turns.

Returns: Number of turns. When the total angle is below 360°, numTurns() is ceiled to 1.

See also: setNumTurns(), setTotalAngle(), totalAngle()

◆ paintEvent()

void QwtKnob::paintEvent ( QPaintEvent * event )

overrideprotectedvirtual

Repaint the knob.

Parameters

event Paint event

◆ scaleDraw() [1/2]

QwtRoundScaleDraw * QwtKnob::scaleDraw ( )

Return the scale draw (non-const version)

Return the scale draw of the knob (non-const version)

Returns: The scale draw

See also: setScaleDraw()

◆ scaleDraw() [2/2]

const QwtRoundScaleDraw * QwtKnob::scaleDraw ( ) const

Return the scale draw (const version)

Return the scale draw of the knob (const version)

Returns: The scale draw

See also: setScaleDraw()

◆ scrolledTo()

double QwtKnob::scrolledTo ( const QPoint & pos ) const

overrideprotectedvirtual

Determine the value for a new position of the mouse.

Parameters

pos	Mouse position

Returns: Value for the mouse position

See also: isScrollPosition()

Implements QwtAbstractSlider.

◆ setAlignment()

void QwtKnob::setAlignment ( Qt::Alignment alignment )

Set alignment of the knob inside contentsRect()

Set the alignment of the knob.

Similar to QLabel::alignment(), the flags decide how to align the knob inside of contentsRect(). The default setting is Qt::AlignCenter.

Parameters

alignment Or'd alignment flags

See also: alignment(), setKnobWidth(), knobRect()

◆ setBorderWidth()

void QwtKnob::setBorderWidth ( int borderWidth )

Set the border width.

Set the knob's border width.

Parameters

borderWidth New border width

◆ setKnobStyle()

void QwtKnob::setKnobStyle ( KnobStyle knobStyle )

Set the knob style.

Set the knob type.

Parameters

knobStyle Knob type

See also: knobStyle(), setBorderWidth()

◆ setKnobWidth()

void QwtKnob::setKnobWidth ( int width )

Set the knob's width (diameter)

Change the knob's width.

Setting a fixed value for the diameter of the knob is helpful for aligning several knobs in a row.

Parameters

width New width

See also: knobWidth(), setAlignment()

Note: Modifies the sizePolicy()

◆ setMarkerSize()

void QwtKnob::setMarkerSize ( int size )

Set the marker size.

Set the size of the marker.

When setting a size <= 0 the marker will automatically be scaled to 40% of the radius of the knob.

Parameters

size	Marker size

See also: markerSize(), markerStyle()

◆ setMarkerStyle()

void QwtKnob::setMarkerStyle ( MarkerStyle markerStyle )

Set the marker style.

Set the marker type of the knob.

Parameters

markerStyle Marker type

See also: markerStyle(), setMarkerSize()

◆ setNumTurns()

void QwtKnob::setNumTurns ( int numTurns )

Set the number of turns for the knob.

Set the number of turns.

When numTurns > 1 the knob can be turned several times around its axis. Otherwise the total angle is floored to 360°.

Parameters

numTurns Number of turns

See also: numTurns(), totalAngle(), setTotalAngle()

◆ setScaleDraw()

void QwtKnob::setScaleDraw ( QwtRoundScaleDraw * scaleDraw )

Set the scale draw.

Change the scale draw of the knob.

For changing the labels of the scales, it is necessary to derive from QwtRoundScaleDraw and overload QwtRoundScaleDraw::label().

Parameters

scaleDraw Scale draw object

See also: scaleDraw()

◆ setTotalAngle()

void QwtKnob::setTotalAngle ( double angle )

Set the total angle which the knob can be turned.

Set the total angle by which the knob can be turned.

The angle has to be between [10, 360] degrees. Angles above 360 (so that the knob can be turned several times around its axis) have to be set using setNumTurns(). The default angle is 270 degrees.

Parameters

angle Angle in degrees

See also: totalAngle(), setNumTurns()

◆ sizeHint()

QSize QwtKnob::sizeHint ( ) const

overridevirtual

Return size hint.

Return the size hint.

Returns: Size hint

◆ totalAngle()

double QwtKnob::totalAngle ( ) const

Return the total angle.

Returns: Total angle in degrees

See also: setTotalAngle(), setNumTurns(), numTurns()

The documentation for this class was generated from the following files:

/home/runner/work/QWT/QWT/src/plot/qwt_knob.h
/home/runner/work/QWT/QWT/src/plot/qwt_knob.cpp

Classes

Public Types

Public Member Functions

Protected Member Functions

Properties

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

◆ KnobStyle

◆ MarkerStyle

Constructor & Destructor Documentation

◆ QwtKnob()

Member Function Documentation

◆ alignment()

◆ changeEvent()

◆ drawFocusIndicator()

◆ drawKnob()

◆ drawMarker()

◆ isScrollPosition()

◆ knobRect()

◆ knobStyle()

◆ knobWidth()

◆ markerSize()

◆ markerStyle()

◆ minimumSizeHint()

◆ numTurns()

◆ paintEvent()

◆ scaleDraw() [1/2]

◆ scaleDraw() [2/2]

◆ scrolledTo()

◆ setAlignment()

◆ setBorderWidth()

◆ setKnobStyle()

◆ setKnobWidth()

◆ setMarkerSize()

◆ setMarkerStyle()

◆ setNumTurns()

◆ setScaleDraw()

◆ setTotalAngle()

◆ sizeHint()

◆ totalAngle()