Qwt User's Guide 5.2.3

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Public Types | Public Member Functions | Protected Member Functions
QwtKnob Class Reference

`#include <qwt_knob.h>`

Inheritance diagram for QwtKnob:
[legend]

List of all members.

## Public Types
enum | Symbol { Line, Dot }
Public Types inherited from QwtAbstractSlider
enum | ScrollMode { ScrNone, ScrMouse, ScrTimer, ScrDirect, ScrPage }

## Public Member Functions
| QwtKnob (QWidget *parent=NULL)
virtual | ~QwtKnob ()
int | borderWidth () const
int | knobWidth () const
virtual QSize | minimumSizeHint () const
const QwtRoundScaleDraw * | scaleDraw () const
QwtRoundScaleDraw * | scaleDraw ()
void | setBorderWidth (int bw)
void | setKnobWidth (int w)
void | setScaleDraw (QwtRoundScaleDraw *)
void | setSymbol (Symbol)
void | setTotalAngle (double angle)
virtual QSize | sizeHint () const
Symbol | symbol () const
double | totalAngle () const
Public Member Functions inherited from QwtAbstractSlider
| QwtAbstractSlider (Qt::Orientation, QWidget *parent=NULL)
virtual | ~QwtAbstractSlider ()
bool | isReadOnly () const
bool | isValid () const
virtual double | mass () const
Qt::Orientation | orientation () const
virtual void | setMass (double val)
virtual void | setOrientation (Qt::Orientation o)
void | setTracking (bool enable)
void | setUpdateTime (int t)
void | setValid (bool valid)
void | stopMoving ()
Public Member Functions inherited from QwtDoubleRange
| QwtDoubleRange ()
virtual | ~QwtDoubleRange ()
virtual void | incPages (int)
double | maxValue () const
double | minValue () const
int | pageSize () const
bool | periodic () const
void | setPeriodic (bool tf)
void | setRange (double vmin, double vmax, double vstep=0.0, int pagesize=1)
void | setStep (double)
double | step () const
double | value () const
Public Member Functions inherited from QwtAbstractScale
| QwtAbstractScale ()
virtual | ~QwtAbstractScale ()
bool | autoScale () const
const QwtScaleEngine * | scaleEngine () const
QwtScaleEngine * | scaleEngine ()
const QwtScaleMap & | scaleMap () const
int | scaleMaxMajor () const
int | scaleMaxMinor () const
void | setAutoScale ()
void | setScale (double vmin, double vmax, double step=0.0)
void | setScale (const QwtDoubleInterval &, double step=0.0)
void | setScale (const QwtScaleDiv &s)
void | setScaleEngine (QwtScaleEngine *)
void | setScaleMaxMajor (int ticks)
void | setScaleMaxMinor (int ticks)

## Protected Member Functions
void | draw (QPainter *p, const QRect &ur)
void | drawKnob (QPainter *p, const QRect &r)
void | drawMarker (QPainter *p, double arc, const QColor &c)
virtual void | paintEvent (QPaintEvent *e)
virtual void | resizeEvent (QResizeEvent *e)
Protected Member Functions inherited from QwtAbstractSlider
virtual void | keyPressEvent (QKeyEvent *e)
virtual void | mouseMoveEvent (QMouseEvent *e)
double | mouseOffset () const
virtual void | mousePressEvent (QMouseEvent *e)
virtual void | mouseReleaseEvent (QMouseEvent *e)
int | scrollMode () const
void | setMouseOffset (double)
virtual void | setPosition (const QPoint &)
virtual void | timerEvent (QTimerEvent *e)
virtual void | wheelEvent (QWheelEvent *e)
Protected Member Functions inherited from QwtDoubleRange
double | exactPrevValue () const
double | exactValue () const
double | prevValue () const
virtual void | stepChange ()
Protected Member Functions inherited from QwtAbstractScale
const QwtAbstractScaleDraw * | abstractScaleDraw () const
QwtAbstractScaleDraw * | abstractScaleDraw ()
void | rescale (double vmin, double vmax, double step=0.0)
void | setAbstractScaleDraw (QwtAbstractScaleDraw *)

## Additional Inherited Members
Public Slots inherited from QwtAbstractSlider
virtual void | fitValue (double val)
virtual void | incValue (int steps)
virtual void | setReadOnly (bool)
virtual void | setValue (double val)
Signals inherited from QwtAbstractSlider
void | sliderMoved (double value)
void | sliderPressed ()
void | sliderReleased ()
void | valueChanged (double value)

## Detailed Description

The Knob Widget.

The QwtKnob widget imitates look and behaviour of a volume knob on a radio. It contains a scale around the knob which is set up automatically or can be configured manually (see QwtAbstractScale). Automatic scrolling is enabled when the user presses a mouse button on the scale. For a description of signals, slots and other members, see QwtAbstractSlider.

See also:
  QwtAbstractSlider and QwtAbstractScale for the descriptions of the inherited members.

## Member Enumeration Documentation

enum QwtKnob::Symbol

Symbol

See also:
  QwtKnob::QwtKnob()

## Constructor & Destructor Documentation

QwtKnob::QwtKnob | ( | QWidget * | parent = `NULL` | ) |
| explicit

Constructor

Parameters:

  parent | Parent widget

## Member Function Documentation

void QwtKnob::draw | ( | QPainter * | painter,
|  | const QRect & | rect
| ) |  |
| protected

Repaint the knob

Parameters:

  painter | Painter
  rect | Update rectangle

void QwtKnob::drawKnob | ( | QPainter * | painter,
|  | const QRect & | r
| ) |  |
| protected

Draw the knob.

Parameters:

  painter | painter
  r | Bounding rectangle of the knob (without scale)

void QwtKnob::drawMarker | ( | QPainter * | p,
|  | double | arc,
|  | const QColor & | c
| ) |  |
| protected

Draw the marker at the knob's front.

Parameters:

  p | Painter
  arc | Angle of the marker
  c | Marker color

QSize QwtKnob::minimumSizeHint | ( |  | ) | const
| virtual

Return a minimum size hint.

Warning:
  The return value of QwtKnob::minimumSizeHint() depends on the font and the scale.

void QwtKnob::paintEvent | ( | QPaintEvent * | e | ) |
| protected virtual

Repaint the knob

Parameters:

  e | Paint event

void QwtKnob::resizeEvent | ( | QResizeEvent * | e | ) |
| protected virtual

Qt Resize 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()

void QwtKnob::setBorderWidth | ( | int | bw | ) |

Set the knob's border width.

Parameters:

  bw | new border width

void QwtKnob::setKnobWidth | ( | int | w | ) |

Change the knob's width.

The specified width must be >= 5, or it will be clipped.

Parameters:

  w | New width

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::setSymbol | ( | QwtKnob::Symbol | s | ) |

Set the symbol of the knob.

See also:
  symbol()

void QwtKnob::setTotalAngle | ( | double | angle | ) |

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

Parameters:

  angle | Angle in degrees.

The default angle is 270 degrees. It is possible to specify an angle of more than 360 degrees so that the knob can be turned several times around its axis.

QSize QwtKnob::sizeHint | ( |  | ) | const
| virtual

Returns:
  minimumSizeHint()

QwtKnob::Symbol QwtKnob::symbol | ( |  | ) | const

Returns:
  symbol of the knob

See also:
  setSymbol()