QwtKnob (3) - Linux Manuals

NAME

QwtKnob -

The Knob Widget.

SYNOPSIS

#include <qwt_knob.h>

Inherits QwtAbstractSlider.

Public Types

enum KnobStyle { Flat, Raised, Sunken, Styled }
Style of the knob surface.
enum MarkerStyle { NoMarker = -1, Tick, Triangle, Dot, Nub, Notch }
Marker type.

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 bw)
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

virtual QSize minimumSizeHint () const

void setScaleDraw (QwtRoundScaleDraw *)

const QwtRoundScaleDraw * scaleDraw () const

QwtRoundScaleDraw * scaleDraw ()

QRect knobRect () const

Protected Member Functions

virtual void paintEvent (QPaintEvent *)

virtual void changeEvent (QEvent *)

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

virtual void drawMarker (QPainter *, const QRectF &, double arc) const
Draw the marker at the knob's front.
virtual double scrolledTo (const QPoint &) const
Determine the value for a new position of the mouse.
virtual bool isScrollPosition (const QPoint &) const
Determine what to do when the user presses a mouse button.

Additional Inherited Members

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

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.

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 (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

Qt::Alignment QwtKnob::alignment () const

Returns:

Alignment of the knob inside of contentsRect()

See Also:

setAlignment(), knobWidth(), knobRect()

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

Handle QEvent::StyleChange and QEvent::FontChange;

Parameters:

event Change event

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

Draw the focus indicator

Parameters:

painter Painter

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)

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

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.

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()

QwtKnob::KnobStyle QwtKnob::knobStyle () const

Returns:

Marker type of the knob

See Also:

setKnobStyle(), setBorderWidth()

int QwtKnob::markerSize () const

Returns:

Marker size

See Also:

setMarkerSize()

QwtKnob::MarkerStyle QwtKnob::markerStyle () const

Returns:

Marker type of the knob

See Also:

setMarkerStyle(), setMarkerSize()

QSize QwtKnob::minimumSizeHint () const [virtual]

Returns:

Minimum size hint

See Also:

sizeHint()

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()

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

Repaint the knob

Parameters:

event Paint event

const QwtRoundScaleDraw * QwtKnob::scaleDraw () const

Returns:

the scale draw of the knob

See Also:

setScaleDraw()

QwtRoundScaleDraw * QwtKnob::scaleDraw ()

Returns:

the scale draw of the knob

See Also:

setScaleDraw()

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.

void QwtKnob::setAlignment (Qt::Alignmentalignment)

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()

void QwtKnob::setBorderWidth (intborderWidth)

Set the knob's border width.

Parameters:

borderWidth new border width

void QwtKnob::setKnobStyle (KnobStyleknobStyle)

Set the knob type.

Parameters:

knobStyle Knob type

See Also:

knobStyle(), setBorderWidth()

void QwtKnob::setKnobWidth (intwidth)

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()

void QwtKnob::setMarkerSize (intsize)

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()

void QwtKnob::setMarkerStyle (MarkerStylemarkerStyle)

Set the marker type of the knob.

Parameters:

markerStyle Marker type

See Also:

markerStyle(), setMarkerSize()

void QwtKnob::setNumTurns (intnumTurns)

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()

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()

void QwtKnob::setTotalAngle (doubleangle)

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()

QSize QwtKnob::sizeHint () const [virtual]

Returns:

sizeHint()

double QwtKnob::totalAngle () const

Returns:

the total angle

See Also:

setTotalAngle(), setNumTurns(), numTurns()

Author

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