QwtKnob Class Reference

The Knob Widget. More...

#include <qwt_knob.h>

Inheritance diagram for QwtKnob:

Inheritance graph
[legend]

List of all members.

Public Types

enum  KnobStyle {
  NoStyle = -1,
  Raised,
  Sunken
}
enum  MarkerStyle {
  NoMarker = -1,
  Tick,
  Dot,
  Nub,
  Notch
}
enum  ScrollMode {
  ScrNone,
  ScrMouse,
  ScrTimer,
  ScrDirect,
  ScrPage
}

Public Slots

virtual void fitValue (double val)
virtual void incValue (int steps)
virtual void setReadOnly (bool)
virtual void setValue (double val)

Signals

void sliderMoved (double value)
void sliderPressed ()
void sliderReleased ()
void valueChanged (double value)

Public Member Functions

bool autoScale () const
int borderWidth () const
virtual void incPages (int)
bool isReadOnly () const
bool isValid () const
KnobStyle knobStyle () const
int knobWidth () const
int markerSize () const
MarkerStyle markerStyle () const
virtual double mass () const
double maxValue () const
virtual QSize minimumSizeHint () const
double minValue () const
Qt::Orientation orientation () const
int pageSize () const
bool periodic () const
 QwtKnob (QWidget *parent=NULL)
QwtRoundScaleDrawscaleDraw ()
const QwtRoundScaleDrawscaleDraw () const
QwtScaleEnginescaleEngine ()
const QwtScaleEnginescaleEngine () const
const QwtScaleMapscaleMap () const
int scaleMaxMajor () const
int scaleMaxMinor () const
void setAutoScale ()
void setBorderWidth (int bw)
void setKnobStyle (KnobStyle)
void setKnobWidth (int w)
void setMarkerSize (int)
void setMarkerStyle (MarkerStyle)
virtual void setMass (double val)
virtual void setOrientation (Qt::Orientation o)
void setPeriodic (bool tf)
void setRange (double vmin, double vmax, double vstep=0.0, int pagesize=1)
void setScale (const QwtScaleDiv &)
void setScale (const QwtInterval &, double step=0.0)
void setScale (double vmin, double vmax, double step=0.0)
void setScaleDraw (QwtRoundScaleDraw *)
void setScaleEngine (QwtScaleEngine *)
void setScaleMaxMajor (int ticks)
void setScaleMaxMinor (int ticks)
void setStep (double)
void setTotalAngle (double angle)
void setTracking (bool enable)
void setUpdateTime (int t)
void setValid (bool valid)
virtual QSize sizeHint () const
double step () const
void stopMoving ()
double totalAngle () const
double value () const
virtual ~QwtKnob ()

Protected Member Functions

QwtAbstractScaleDrawabstractScaleDraw ()
const QwtAbstractScaleDrawabstractScaleDraw () const
virtual void changeEvent (QEvent *)
virtual void drawKnob (QPainter *, const QRectF &) const
virtual void drawMarker (QPainter *, const QRectF &, double arc) const
double exactPrevValue () const
double exactValue () const
virtual void getScrollMode (const QPoint &, QwtAbstractSlider::ScrollMode &, int &direction) const
virtual double getValue (const QPoint &p)
virtual void keyPressEvent (QKeyEvent *e)
virtual void mouseMoveEvent (QMouseEvent *e)
double mouseOffset () const
virtual void mousePressEvent (QMouseEvent *e)
virtual void mouseReleaseEvent (QMouseEvent *e)
virtual void paintEvent (QPaintEvent *)
double prevValue () const
void rescale (double vmin, double vmax, double step=0.0)
virtual void resizeEvent (QResizeEvent *)
int scrollMode () const
void setAbstractScaleDraw (QwtAbstractScaleDraw *)
void setMouseOffset (double)
virtual void setPosition (const QPoint &)
virtual void stepChange ()
virtual void timerEvent (QTimerEvent *e)
virtual void wheelEvent (QWheelEvent *e)


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.

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

Member Enumeration Documentation

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:
NoStyle  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

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.
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

Scroll mode

See also:
getScrollMode()
Enumerator:
ScrNone  Scrolling switched off. Don't change the value.
ScrMouse  Change the value while the user keeps the button pressed and moves the mouse.
ScrTimer  Automatic scrolling. Increment the value in the specified direction as long as the user keeps the button pressed.
ScrPage  Automatic scrolling. Same as ScrTimer, but increment by page size.


Constructor & Destructor Documentation

QwtKnob::QwtKnob ( QWidget *  parent = NULL  )  [explicit]

Constructor

Parameters:
parent Parent widget

QwtKnob::~QwtKnob (  )  [virtual]

Destructor.


Member Function Documentation

QwtAbstractScaleDraw * QwtAbstractScale::abstractScaleDraw (  )  [protected, inherited]

Returns:
Scale draw
See also:
setAbstractScaleDraw()

const QwtAbstractScaleDraw * QwtAbstractScale::abstractScaleDraw (  )  const [protected, inherited]

Returns:
Scale draw
See also:
setAbstractScaleDraw()

bool QwtAbstractScale::autoScale (  )  const [inherited]

Returns:
true if autoscaling is enabled

int QwtKnob::borderWidth (  )  const

Return the border width.

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

Handle QEvent::StyleChange and QEvent::FontChange;

Parameters:
event Change event

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,
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

double QwtDoubleRange::exactPrevValue (  )  const [protected, inherited]

Returns the exact previous value.

double QwtDoubleRange::exactValue (  )  const [protected, inherited]

Returns the exact value.

The exact value is the value which QwtDoubleRange::value would return if the value were not adjusted to the step raster. It differs from the current value only if fitValue() or incValue() have been used before. This function is intended for internal use in derived classes.

void QwtAbstractSlider::fitValue ( double  value  )  [virtual, slot, inherited]

Set the slider's value to the nearest integer multiple of the step size.

Parameters:
value Value
See also:
setValue(), incValue()

Reimplemented from QwtDoubleRange.

void QwtKnob::getScrollMode ( const QPoint &  pos,
QwtAbstractSlider::ScrollMode scrollMode,
int &  direction 
) const [protected, virtual]

Set the scrolling mode and direction.

Called by QwtAbstractSlider

Parameters:
pos Point in question
scrollMode Scrolling mode
direction Direction

Implements QwtAbstractSlider.

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

Determine the value corresponding to a specified position.

Called by QwtAbstractSlider

Parameters:
pos point

Implements QwtAbstractSlider.

void QwtDoubleRange::incPages ( int  nPages  )  [virtual, inherited]

Increment the value by a specified number of pages.

Parameters:
nPages Number of pages to increment. A negative number decrements the value.
Warning:
The Page size is specified in the constructor.

void QwtAbstractSlider::incValue ( int  steps  )  [virtual, slot, inherited]

Increment the value by a specified number of steps.

Parameters:
steps number of steps
See also:
setValue()

Reimplemented from QwtDoubleRange.

bool QwtAbstractSlider::isReadOnly (  )  const [inherited]

In read only mode the slider can't be controlled by mouse or keyboard.

Returns:
true if read only
See also:
setReadOnly()

bool QwtAbstractSlider::isValid (  )  const [inline, inherited]

See also:
QwtDblRange::isValid()

Reimplemented from QwtDoubleRange.

void QwtAbstractSlider::keyPressEvent ( QKeyEvent *  e  )  [protected, virtual, inherited]

Handles key events

  • Key_Down, KeyLeft
    Decrement by 1
  • Key_Up, Key_Right
    Increment by 1

Parameters:
e Key event
See also:
isReadOnly()

Reimplemented in QwtCompass, and QwtDial.

QwtKnob::KnobStyle QwtKnob::knobStyle (  )  const

Returns:
Marker type of the knob
See also:
setKnobStyle(), setBorderWidth()

int QwtKnob::knobWidth (  )  const

Return the width of the knob.

int QwtKnob::markerSize (  )  const

Return the marker size.

QwtKnob::MarkerStyle QwtKnob::markerStyle (  )  const

Returns:
Marker type of the knob
See also:
setMarkerStyle(), setMarkerSize()

double QwtAbstractSlider::mass (  )  const [virtual, inherited]

Returns:
mass
See also:
setMass()

Reimplemented in QwtWheel.

double QwtDoubleRange::maxValue (  )  const [inherited]

Returns the value of the second border of the range.

maxValue returns the value which has been specified as the second parameter in QwtDoubleRange::setRange.

See also:
setRange()

Reimplemented in QwtCounter.

QSize QwtKnob::minimumSizeHint (  )  const [virtual]

Return a minimum size hint.

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

double QwtDoubleRange::minValue (  )  const [inherited]

Returns the value at the first border of the range.

minValue returns the value which has been specified as the first parameter in setRange().

See also:
setRange()

Reimplemented in QwtCounter.

void QwtAbstractSlider::mouseMoveEvent ( QMouseEvent *  e  )  [protected, virtual, inherited]

Mouse Move Event handler

Parameters:
e Mouse event

double QwtAbstractSlider::mouseOffset (  )  const [protected, inherited]

See also:
setMouseOffset()

void QwtAbstractSlider::mousePressEvent ( QMouseEvent *  e  )  [protected, virtual, inherited]

Mouse press event handler

Parameters:
e Mouse event

void QwtAbstractSlider::mouseReleaseEvent ( QMouseEvent *  e  )  [protected, virtual, inherited]

Mouse Release Event handler

Parameters:
e Mouse event

Qt::Orientation QwtAbstractSlider::orientation (  )  const [inherited]

Returns:
Orientation
See also:
setOrientation()

int QwtDoubleRange::pageSize (  )  const [inherited]

Returns the page size in steps.

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

Repaint the knob

Parameters:
event Paint event

bool QwtDoubleRange::periodic (  )  const [inherited]

Returns true if the range is periodic.

See also:
setPeriodic()

double QwtDoubleRange::prevValue (  )  const [protected, inherited]

Returns the previous value.

void QwtAbstractScale::rescale ( double  vmin,
double  vmax,
double  stepSize = 0.0 
) [protected, inherited]

Recalculate the scale division and update the scale draw.

Parameters:
vmin Lower limit of the scale interval
vmax Upper limit of the scale interval
stepSize Major step size
See also:
scaleChange()

void QwtKnob::resizeEvent ( QResizeEvent *  event  )  [protected, virtual]

Qt Resize Event

Parameters:
event Resize event

QwtRoundScaleDraw * QwtKnob::scaleDraw (  ) 

Returns:
the scale draw of the knob
See also:
setScaleDraw()

const QwtRoundScaleDraw * QwtKnob::scaleDraw (  )  const

Returns:
the scale draw of the knob
See also:
setScaleDraw()

QwtScaleEngine * QwtAbstractScale::scaleEngine (  )  [inherited]

Returns:
Scale engine
See also:
setScaleEngine()

const QwtScaleEngine * QwtAbstractScale::scaleEngine (  )  const [inherited]

Returns:
Scale engine
See also:
setScaleEngine()

const QwtScaleMap & QwtAbstractScale::scaleMap (  )  const [inherited]

int QwtAbstractScale::scaleMaxMajor (  )  const [inherited]

Returns:
Max. number of major tick intervals The default value is 5.

int QwtAbstractScale::scaleMaxMinor (  )  const [inherited]

Returns:
Max. number of minor tick intervals The default value is 3.

int QwtAbstractSlider::scrollMode (  )  const [protected, inherited]

sa ScrollMode

void QwtAbstractScale::setAbstractScaleDraw ( QwtAbstractScaleDraw scaleDraw  )  [protected, inherited]

Set a scale draw.

scaleDraw has to be created with new and will be deleted in ~QwtAbstractScale or the next call of setAbstractScaleDraw.

void QwtAbstractScale::setAutoScale (  )  [inherited]

Advise the widget to control the scale range internally.

Autoscaling is on by default.

See also:
setScale(), autoScale()

void QwtKnob::setBorderWidth ( int  borderWidth  ) 

Set the knob's border width.

Parameters:
borderWidth new border width

void QwtKnob::setKnobStyle ( KnobStyle  knobStyle  ) 

Set the knob type.

Parameters:
knobStyle Knob type
See also:
knobStyle(), setBorderWidth()

void QwtKnob::setKnobWidth ( int  width  ) 

Change the knob's width.

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

Parameters:
width New width

void QwtKnob::setMarkerSize ( int  size  ) 

Set the size of the marker.

See also:
markerSize(), markerStyle()

void QwtKnob::setMarkerStyle ( MarkerStyle  markerStyle  ) 

Set the marker type of the knob.

Parameters:
markerStyle Marker type
See also:
markerStyle(), setMarkerSize()

void QwtAbstractSlider::setMass ( double  val  )  [virtual, inherited]

Set the slider's mass for flywheel effect.

If the slider's mass is greater then 0, it will continue to move after the mouse button has been released. Its speed decreases with time at a rate depending on the slider's mass. A large mass means that it will continue to move for a long time.

Derived widgets may overload this function to make it public.

Parameters:
val New mass in kg
See also:
mass()

Reimplemented in QwtWheel.

void QwtAbstractSlider::setMouseOffset ( double  offset  )  [protected, inherited]

See also:
mouseOffset()

void QwtAbstractSlider::setOrientation ( Qt::Orientation  o  )  [virtual, inherited]

Set the orientation.

Parameters:
o Orientation. Allowed values are Qt::Horizontal and Qt::Vertical.

Reimplemented in QwtSlider, and QwtWheel.

void QwtDoubleRange::setPeriodic ( bool  tf  )  [inherited]

Make the range periodic.

When the range is periodic, the value will be set to a point inside the interval such that

point = value + n * width 

if the user tries to set a new value which is outside the range. If the range is nonperiodic (the default), values outside the range will be clipped.

Parameters:
tf true for a periodic range

void QwtAbstractSlider::setPosition ( const QPoint &  p  )  [protected, virtual, inherited]

Move the slider to a specified point, adjust the value and emit signals if necessary.

void QwtDoubleRange::setRange ( double  vmin,
double  vmax,
double  vstep = 0.0,
int  pageSize = 1 
) [inherited]

Specify range and step size.

Parameters:
vmin lower boundary of the interval
vmax higher boundary of the interval
vstep step width
pageSize page size in steps
Warning:
  • A change of the range changes the value if it lies outside the new range. The current value will *not* be adjusted to the new step raster.
  • vmax < vmin is allowed.
  • If the step size is left out or set to zero, it will be set to 1/100 of the interval length.
  • If the step size has an absurd value, it will be corrected to a better one.

void QwtAbstractSlider::setReadOnly ( bool  readOnly  )  [virtual, slot, inherited]

En/Disable read only mode

In read only mode the slider can't be controlled by mouse or keyboard.

Parameters:
readOnly Enables in case of true
See also:
isReadOnly()

void QwtAbstractScale::setScale ( const QwtScaleDiv scaleDiv  )  [inherited]

Specify a scale.

Disable autoscaling and define a scale by a scale division

Parameters:
scaleDiv Scale division
See also:
setAutoScale()

void QwtAbstractScale::setScale ( const QwtInterval interval,
double  stepSize = 0.0 
) [inherited]

Specify a scale.

Disable autoscaling and define a scale by an interval and a step size

Parameters:
interval Interval
stepSize major step size
See also:
setAutoScale()

void QwtAbstractScale::setScale ( double  vmin,
double  vmax,
double  stepSize = 0.0 
) [inherited]

Specify a scale.

Disable autoscaling and define a scale by an interval and a step size

Parameters:
vmin lower limit of the scale interval
vmax upper limit of the scale interval
stepSize major step size
See also:
setAutoScale()

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 QwtAbstractScale::setScaleEngine ( QwtScaleEngine scaleEngine  )  [inherited]

Set a scale engine.

The scale engine is responsible for calculating the scale division, and in case of auto scaling how to align the scale.

scaleEngine has to be created with new and will be deleted in ~QwtAbstractScale or the next call of setScaleEngine.

void QwtAbstractScale::setScaleMaxMajor ( int  ticks  )  [inherited]

Set the maximum number of major tick intervals.

The scale's major ticks are calculated automatically such that the number of major intervals does not exceed ticks. The default value is 5.

Parameters:
ticks maximal number of major ticks.
See also:
QwtAbstractScaleDraw

void QwtAbstractScale::setScaleMaxMinor ( int  ticks  )  [inherited]

Set the maximum number of minor tick intervals.

The scale's minor ticks are calculated automatically such that the number of minor intervals does not exceed ticks. The default value is 3.

Parameters:
ticks 
See also:
QwtAbstractScaleDraw

void QwtDoubleRange::setStep ( double  vstep  )  [inherited]

Change the step raster.

Parameters:
vstep new step width
Warning:
The value will not be adjusted to the new step raster.

Reimplemented in QwtCounter.

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.

void QwtAbstractSlider::setTracking ( bool  enable  )  [inherited]

Enables or disables tracking.

If tracking is enabled, the slider emits a valueChanged() signal whenever its value changes (the default behaviour). If tracking is disabled, the value changed() signal will only be emitted if:

  • the user releases the mouse button and the value has changed or
  • at the end of automatic scrolling.
Tracking is enabled by default.
Parameters:
enable true (enable) or false (disable) tracking.

void QwtAbstractSlider::setUpdateTime ( int  t  )  [inherited]

Specify the update interval for automatic scrolling.

Parameters:
t update interval in milliseconds
See also:
getScrollMode()

void QwtAbstractSlider::setValid ( bool  valid  )  [inline, inherited]

Parameters:
valid true/false
See also:
QwtDblRange::isValid()

Reimplemented from QwtDoubleRange.

void QwtAbstractSlider::setValue ( double  val  )  [virtual, slot, inherited]

Move the slider to a specified value.

This function can be used to move the slider to a value which is not an integer multiple of the step size.

Parameters:
val new value
See also:
fitValue()

Reimplemented from QwtDoubleRange.

QSize QwtKnob::sizeHint (  )  const [virtual]

void QwtAbstractSlider::sliderMoved ( double  value  )  [signal, inherited]

This signal is emitted when the user moves the slider with the mouse.

Parameters:
value new value

void QwtAbstractSlider::sliderPressed (  )  [signal, inherited]

This signal is emitted when the user presses the movable part of the slider (start ScrMouse Mode).

void QwtAbstractSlider::sliderReleased (  )  [signal, inherited]

This signal is emitted when the user releases the movable part of the slider.

double QwtDoubleRange::step (  )  const [inherited]

Returns:
the step size
See also:
setStep(), setRange()

Reimplemented in QwtCounter.

void QwtDoubleRange::stepChange (  )  [protected, virtual, inherited]

Notify a change of the step size.

This virtual function is called whenever the step size changes. The default implementation does nothing.

void QwtAbstractSlider::stopMoving (  )  [inherited]

Stop updating if automatic scrolling is active.

void QwtAbstractSlider::timerEvent ( QTimerEvent *  e  )  [protected, virtual, inherited]

Qt timer event

Parameters:
e Timer event

double QwtKnob::totalAngle (  )  const

Return the total angle.

double QwtDoubleRange::value (  )  const [inherited]

Returns the current value.

Reimplemented in QwtCounter.

void QwtAbstractSlider::valueChanged ( double  value  )  [signal, inherited]

Notify a change of value.

In the default setting (tracking enabled), this signal will be emitted every time the value changes ( see setTracking() ).

Parameters:
value new value

void QwtAbstractSlider::wheelEvent ( QWheelEvent *  e  )  [protected, virtual, inherited]

Wheel Event handler

Parameters:
e Whell event


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