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
Qt::Alignment	alignment () const
int	borderWidth () const
QRect	knobRect () const
KnobStyle	knobStyle () const
int	knobWidth () const
int	markerSize () const
MarkerStyle	markerStyle () const
virtual QSize	minimumSizeHint () const
int	numTurns () const
	QwtKnob (QWidget *parent=NULL)
	Constructor.
const QwtRoundScaleDraw *	scaleDraw () const
QwtRoundScaleDraw *	scaleDraw ()
void	setAlignment (Qt::Alignment)
	Set the alignment of the knob.
void	setBorderWidth (int bw)
	Set the knob's border width.
void	setKnobStyle (KnobStyle)
	Set the knob type.
void	setKnobWidth (int)
	Change the knob's width.
void	setMarkerSize (int)
	Set the size of the marker.
void	setMarkerStyle (MarkerStyle)
	Set the marker type of the knob.
void	setNumTurns (int)
	Set the number of turns.
void	setScaleDraw (QwtRoundScaleDraw *)
void	setTotalAngle (double angle)
	Set the total angle by which the knob can be turned.
virtual QSize	sizeHint () const
double	totalAngle () const
virtual	~QwtKnob ()
	Destructor.
Protected Member Functions
virtual void	changeEvent (QEvent *)
virtual void	drawFocusIndicator (QPainter *) const
virtual void	drawKnob (QPainter *, const QRectF &) const
	Draw the knob.
virtual void	drawMarker (QPainter *, const QRectF &, double arc) const
	Draw the marker at the knob's front.
virtual bool	isScrollPosition (const QPoint &) const
	Determine what to do when the user presses a mouse button.
virtual void	paintEvent (QPaintEvent *)
virtual double	scrolledTo (const QPoint &) const
	Determine the value for a new position of the mouse.
Properties
Qt::Alignment	alignment
int	borderWidth
	Return the border width.
KnobStyle	knobStyle
int	knobWidth
	Return the width of the knob.
int	markerSize
MarkerStyle	markerStyle
int	numTurns
double	totalAngle
Private Attributes
PrivateData *	d_data

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.

Definition at line 42 of file qwt_knob.h.

Member Enumeration Documentation

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.

Definition at line 66 of file qwt_knob.h.

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

Definition at line 95 of file qwt_knob.h.

Constructor & Destructor Documentation

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()

Definition at line 110 of file qwt_knob.cpp.

QwtKnob::~QwtKnob ( ) [virtual]

Destructor.

Definition at line 127 of file qwt_knob.cpp.

Member Function Documentation

Qt::Alignment QwtKnob::alignment ( ) const

int QwtKnob::borderWidth ( ) const

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

Handle QEvent::StyleChange and QEvent::FontChange;

Parameters:

event Change event

Reimplemented from QwtAbstractScale.

Definition at line 438 of file qwt_knob.cpp.

void QwtKnob::drawFocusIndicator ( QPainter * painter ) const [protected, virtual]

Draw the focus indicator

Parameters:

painter Painter

Definition at line 706 of file qwt_knob.cpp.

void QwtKnob::drawKnob	(	QPainter *	painter,
		const QRectF &	knobRect
	)		const `[protected, virtual]`

Draw the knob.

Parameters:

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

Definition at line 496 of file qwt_knob.cpp.

void QwtKnob::drawMarker	(	QPainter *	painter,
		const QRectF &	rect,
		double	angle
	)		const `[protected, virtual]`

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 )

Definition at line 583 of file qwt_knob.cpp.

bool QwtKnob::isScrollPosition ( const QPoint & pos ) const [protected, virtual]

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.

Definition at line 354 of file qwt_knob.cpp.

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()

Definition at line 299 of file qwt_knob.cpp.

KnobStyle QwtKnob::knobStyle ( ) const

int QwtKnob::knobWidth ( ) const

int QwtKnob::markerSize ( ) const

MarkerStyle QwtKnob::markerStyle ( ) const

QSize QwtKnob::minimumSizeHint ( ) const [virtual]

Returns:: Minimum size hint

See also:: sizeHint()

Definition at line 852 of file qwt_knob.cpp.

int QwtKnob::numTurns ( ) const

void QwtKnob::paintEvent ( QPaintEvent * event ) [protected, virtual]

Repaint the knob

Parameters:

event Paint event

Definition at line 458 of file qwt_knob.cpp.

const QwtRoundScaleDraw * QwtKnob::scaleDraw ( ) const

Returns:: the scale draw of the knob

See also:: setScaleDraw()

Definition at line 279 of file qwt_knob.cpp.

QwtRoundScaleDraw * QwtKnob::scaleDraw ( )

Returns:: the scale draw of the knob

See also:: setScaleDraw()

Definition at line 288 of file qwt_knob.cpp.

double QwtKnob::scrolledTo ( const QPoint & pos ) const [protected, virtual]

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.

Definition at line 380 of file qwt_knob.cpp.

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()

Definition at line 739 of file qwt_knob.cpp.

void QwtKnob::setBorderWidth ( int borderWidth )

Set the knob's border width.

Parameters:

borderWidth new border width

Definition at line 799 of file qwt_knob.cpp.

void QwtKnob::setKnobStyle ( KnobStyle knobStyle )

Set the knob type.

Parameters:

knobStyle Knob type

See also:: knobStyle(), setBorderWidth()

Definition at line 138 of file qwt_knob.cpp.

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()

Definition at line 768 of file qwt_knob.cpp.

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()

Definition at line 821 of file qwt_knob.cpp.

void QwtKnob::setMarkerStyle ( MarkerStyle markerStyle )

Set the marker type of the knob.

Parameters:

markerStyle Marker type

See also:: markerStyle(), setMarkerSize()

Definition at line 162 of file qwt_knob.cpp.

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()

Definition at line 226 of file qwt_knob.cpp.

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()

Definition at line 266 of file qwt_knob.cpp.

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.