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=NULL)
	Constructor.

virtual	~QwtKnob ()
	Destructor.

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

Qt::Alignment	alignment () const

void	setKnobWidth (int)
	Change the knob's width.

int	knobWidth () const
	Return the width of the knob.

void	setNumTurns (int)
	Set the number of turns.

int	numTurns () const

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

double	totalAngle () const

void	setKnobStyle (KnobStyle)
	Set the knob type.

KnobStyle	knobStyle () const

void	setBorderWidth (int)
	Set the knob's border width.

int	borderWidth () const
	Return the border width.

void	setMarkerStyle (MarkerStyle)
	Set the marker type of the knob.

MarkerStyle	markerStyle () const

void	setMarkerSize (int)
	Set the size of the marker.

int	markerSize () const

virtual QSize	sizeHint () const QWT_OVERRIDE

virtual QSize	minimumSizeHint () const QWT_OVERRIDE

void	setScaleDraw (QwtRoundScaleDraw *)
	Change the scale draw of the knob.

const QwtRoundScaleDraw *	scaleDraw () const

QwtRoundScaleDraw *	scaleDraw ()

QRect	knobRect () const
	Calculate the bounding rectangle of the knob without the scale.

Public Member Functions inherited from QwtAbstractSlider
	QwtAbstractSlider (QWidget *parent=NULL)
	Constructor.

virtual	~QwtAbstractSlider ()
	Destructor.

void	setValid (bool)
	Set the value to be valid/invalid.

bool	isValid () const

double	value () const
	Returns the current value.

void	setWrapping (bool)
	If wrapping is true stepping up from upperBound() value will take you to the minimum() value and vice versa.

bool	wrapping () const

void	setTotalSteps (uint)
	Set the number of steps.

uint	totalSteps () const

void	setSingleSteps (uint)
	Set the number of steps for a single increment.

uint	singleSteps () const

void	setPageSteps (uint)
	Set the number of steps for a page increment.

uint	pageSteps () const

void	setStepAlignment (bool)
	Enable step alignment.

bool	stepAlignment () const

void	setTracking (bool)
	Enables or disables tracking.

bool	isTracking () const

void	setReadOnly (bool)
	En/Disable read only mode.

bool	isReadOnly () const
	In read only mode the slider can't be controlled by mouse or keyboard.

void	setInvertedControls (bool)
	Invert wheel and key events.

bool	invertedControls () const

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

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)
	Set the lower bound of the scale.

double	lowerBound () const

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

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
	Translate a scale value into a widget coordinate.

double	invTransform (int) const
	Translate a widget coordinate into a scale value.

bool	isInverted () const

double	minimum () const

double	maximum () const

const QwtScaleMap &	scaleMap () const

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

virtual void	changeEvent (QEvent *) QWT_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 QWT_OVERRIDE
	Determine the value for a new position of the mouse.

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

Protected Member Functions inherited from QwtAbstractSlider
virtual void	mousePressEvent (QMouseEvent *) QWT_OVERRIDE
	Mouse press event handler.

virtual void	mouseReleaseEvent (QMouseEvent *) QWT_OVERRIDE
	Mouse Release Event handler.

virtual void	mouseMoveEvent (QMouseEvent *) QWT_OVERRIDE
	Mouse Move Event handler.

virtual void	keyPressEvent (QKeyEvent *) QWT_OVERRIDE
	Handles key events.

virtual void	wheelEvent (QWheelEvent *) QWT_OVERRIDE
	Wheel Event handler.

void	incrementValue (int stepCount)
	Increment the slider.

virtual void	scaleChange () QWT_OVERRIDE
	Update the slider according to modifications of the scale.

virtual void	sliderChange ()
	Calling update()

double	incrementedValue (double value, int stepCount) const
	Increment a value.

Protected Member Functions inherited from QwtAbstractScale
void	rescale (double lowerBound, double upperBound, double stepSize)
	Recalculate the scale division and update the scale.

void	setAbstractScaleDraw (QwtAbstractScaleDraw *)
	Set a scale draw.

const QwtAbstractScaleDraw *	abstractScaleDraw () const

QwtAbstractScaleDraw *	abstractScaleDraw ()

void	updateScaleDraw ()
	Recalculate ticks and scale boundaries.

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 to the specified value.

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

void	sliderPressed ()
	This signal is emitted when the user presses the movable part of the slider.

void	sliderReleased ()
	This signal is emitted when the user releases the movable part of the slider.

void	sliderMoved (double value)
	This signal is 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 it is used for 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 build from QPalette::Light and QPalette::Mid.
Notch	Draw a sunken ellipse with a gradient build from QPalette::Light and QPalette::Mid.

Constructor & Destructor Documentation

◆ QwtKnob()

QwtKnob::QwtKnob ( QWidget * parent = NULL )

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

Returns: Alignment of the knob inside of contentsRect()

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

◆ changeEvent()

void QwtKnob::changeEvent ( QEvent * event )

protectedvirtual

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

protectedvirtual

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

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

Returns: Marker type of the knob

See also: setKnobStyle(), setBorderWidth()

◆ markerSize()

int QwtKnob::markerSize ( ) const

Returns: Marker size

See also: setMarkerSize()

◆ markerStyle()

QwtKnob::MarkerStyle QwtKnob::markerStyle ( ) const

Returns: Marker type of the knob

See also: setMarkerStyle(), setMarkerSize()

◆ minimumSizeHint()

QSize QwtKnob::minimumSizeHint ( ) const

virtual

Returns: Minimum size hint

See also: sizeHint()

◆ numTurns()

int QwtKnob::numTurns ( ) const

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 )

protectedvirtual

Repaint the knob.

Parameters

event Paint event

◆ scaleDraw() [1/2]

QwtRoundScaleDraw * QwtKnob::scaleDraw ( )

Returns: the scale draw of the knob

See also: setScaleDraw()

◆ scaleDraw() [2/2]

const QwtRoundScaleDraw * QwtKnob::scaleDraw ( ) const

Returns: the scale draw of the knob

See also: setScaleDraw()

◆ scrolledTo()

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

protectedvirtual

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 the alignment of the knob.

Similar to a 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 knob's border width.

Parameters

borderWidth new border width

◆ setKnobStyle()

void QwtKnob::setKnobStyle ( KnobStyle knobStyle )

Set the knob type.

Parameters

knobStyle Knob type

See also: knobStyle(), setBorderWidth()

◆ setKnobWidth()

void QwtKnob::setKnobWidth ( int width )

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 size of the marker.

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

See also: markerSize(), markerStyle()

◆ setMarkerStyle()

void QwtKnob::setMarkerStyle ( MarkerStyle markerStyle )

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.

When numTurns > 1 the knob can be turned several times around its axis

otherwise the total angle is floored to 360°.

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

◆ setScaleDraw()

void QwtKnob::setScaleDraw ( QwtRoundScaleDraw * scaleDraw )

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().

See also: scaleDraw()

◆ setTotalAngle()

void QwtKnob::setTotalAngle ( double angle )

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

Parameters

angle Angle in degrees.

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.

See also: totalAngle(), setNumTurns()

◆ sizeHint()

QSize QwtKnob::sizeHint ( ) const

virtual

Returns: sizeHint()

◆ totalAngle()

double QwtKnob::totalAngle ( ) const

Returns: the total angle

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

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

/home/runner/work/QWT/QWT/src/qwt_knob.h
/home/runner/work/QWT/QWT/src/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()

◆ markerSize()

◆ markerStyle()

◆ minimumSizeHint()

◆ numTurns()

◆ paintEvent()

◆ scaleDraw() [1/2]

◆ scaleDraw() [2/2]

◆ scrolledTo()

◆ setAlignment()

◆ setBorderWidth()

◆ setKnobStyle()

◆ setKnobWidth()

◆ setMarkerSize()

◆ setMarkerStyle()

◆ setNumTurns()

◆ setScaleDraw()

◆ setTotalAngle()

◆ sizeHint()

◆ totalAngle()