Qwt User's Guide: QwtDial Class Reference

Qwt User's Guide 6.1.2

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QwtDial Class Reference

QwtDial class provides a rounded range control. More...

`#include <qwt_dial.h>`

Inheritance diagram for QwtDial:
[legend]

## Public Types
enum | Shadow { Plain = QFrame::Plain, Raised = QFrame::Raised, Sunken = QFrame::Sunken }
| Frame shadow. More...
enum | Mode { RotateNeedle, RotateScale }
| Mode controlling whether the needle or the scale is rotating. More...

## Public Member Functions
| QwtDial (QWidget *parent=NULL)
| Constructor. More...
virtual | ~QwtDial ()
| Destructor.
void | setFrameShadow (Shadow)
Shadow | frameShadow () const
void | setLineWidth (int)
int | lineWidth () const
void | setMode (Mode)
| Change the mode of the dial. More...
Mode | mode () const
void | setScaleArc (double min, double max)
void | setMinScaleArc (double min)
double | minScaleArc () const
void | setMaxScaleArc (double min)
double | maxScaleArc () const
virtual void | setOrigin (double)
| Change the origin. More...
double | origin () const
void | setNeedle (QwtDialNeedle *)
const QwtDialNeedle * | needle () const
QwtDialNeedle * | needle ()
QRect | boundingRect () const
QRect | innerRect () const
virtual QRect | scaleInnerRect () const
virtual QSize | sizeHint () const
virtual QSize | minimumSizeHint () const
void | setScaleDraw (QwtRoundScaleDraw *)
QwtRoundScaleDraw * | scaleDraw ()
const QwtRoundScaleDraw * | scaleDraw () const
Public Member Functions inherited from QwtAbstractSlider
| QwtAbstractSlider (QWidget *parent=NULL)
| Constructor. More...
virtual | ~QwtAbstractSlider ()
| Destructor.
void | setValid (bool)
bool | isValid () const
double | value () const
| Returns the current value.
void | setWrapping (bool)
bool | wrapping () const
void | setTotalSteps (uint)
| Set the number of steps. More...
uint | totalSteps () const
void | setSingleSteps (uint)
| Set the number of steps for a single increment. More...
uint | singleSteps () const
void | setPageSteps (uint)
| Set the number of steps for a page increment. More...
uint | pageSteps () const
void | setStepAlignment (bool)
| Enable step alignment. More...
bool | stepAlignment () const
void | setTracking (bool)
| Enables or disables tracking. More...
bool | isTracking () const
void | setReadOnly (bool)
bool | isReadOnly () const
void | setInvertedControls (bool)
bool | invertedControls () const
Public Member Functions inherited from QwtAbstractScale
| QwtAbstractScale (QWidget *parent=NULL)
virtual | ~QwtAbstractScale ()
| Destructor.
void | setScale (double lowerBound, double upperBound)
| Specify a scale. More...
void | setScale (const QwtInterval &)
| Specify a scale. More...
void | setScale (const QwtScaleDiv &)
| Specify a scale. More...
const QwtScaleDiv & | scaleDiv () const
void | setLowerBound (double value)
double | lowerBound () const
void | setUpperBound (double value)
double | upperBound () const
void | setScaleStepSize (double stepSize)
| Set the step size used for calculating a scale division. More...
double | scaleStepSize () const
void | setScaleMaxMajor (int ticks)
| Set the maximum number of major tick intervals. More...
int | scaleMaxMinor () const
void | setScaleMaxMinor (int ticks)
| Set the maximum number of minor tick intervals. More...
int | scaleMaxMajor () const
void | setScaleEngine (QwtScaleEngine *)
| Set a scale engine. More...
const QwtScaleEngine * | scaleEngine () const
QwtScaleEngine * | scaleEngine ()
int | transform (double) const
double | invTransform (int) const
bool | isInverted () const
double | minimum () const
double | maximum () const
const QwtScaleMap & | scaleMap () const

## Protected Member Functions
virtual void | wheelEvent (QWheelEvent *)
virtual void | paintEvent (QPaintEvent *)
virtual void | changeEvent (QEvent *)
virtual void | drawFrame (QPainter *p)
virtual void | drawContents (QPainter *) const
| Draw the contents inside the frame. More...
virtual void | drawFocusIndicator (QPainter *) const
void | invalidateCache ()
virtual void | drawScale (QPainter *, const QPointF &center, double radius) const
virtual void | drawScaleContents (QPainter *painter, const QPointF &center, double radius) const
virtual void | drawNeedle (QPainter *, const QPointF &, double radius, double direction, QPalette::ColorGroup) const
virtual double | scrolledTo (const QPoint &) const
| Determine the value for a new position of the slider handle. More...
virtual bool | isScrollPosition (const QPoint &) const
| Determine what to do when the user presses a mouse button. More...
virtual void | sliderChange ()
| Calling update()
virtual void | scaleChange ()
Protected Member Functions inherited from QwtAbstractSlider
virtual void | mousePressEvent (QMouseEvent *)
virtual void | mouseReleaseEvent (QMouseEvent *)
virtual void | mouseMoveEvent (QMouseEvent *)
virtual void | keyPressEvent (QKeyEvent *)
void | incrementValue (int numSteps)
double | incrementedValue (double value, int stepCount) const
Protected Member Functions inherited from QwtAbstractScale
void | rescale (double lowerBound, double upperBound, double stepSize)
void | setAbstractScaleDraw (QwtAbstractScaleDraw *)
| Set a scale draw. More...
const QwtAbstractScaleDraw * | abstractScaleDraw () const
QwtAbstractScaleDraw * | abstractScaleDraw ()

## Additional Inherited Members
Public Slots inherited from QwtAbstractSlider
void | setValue (double val)
Signals inherited from QwtAbstractSlider
void | valueChanged (double value)
| Notify a change of value. More...
void | sliderPressed ()
void | sliderReleased ()
void | sliderMoved (double value)

## Detailed Description

QwtDial class provides a rounded range control.

QwtDial is intended as base class for dial widgets like speedometers, compass widgets, clocks ...

A dial contains a scale and a needle indicating the current value of the dial. Depending on Mode one of them is fixed and the other is rotating. If not isReadOnly() the dial can be rotated by dragging the mouse or using keyboard inputs (see QwtAbstractSlider::keyPressEvent()). A dial might be wrapping, what means a rotation below/above one limit continues on the other limit (f.e compass). The scale might cover any arc of the dial, its values are related to the origin() of the dial.

Often dials have to be updated very often according to values from external devices. For these high refresh rates QwtDial caches as much as possible. For derived classes it might be necessary to clear these caches manually according to attribute changes using invalidateCache().

See Also
  QwtCompass, QwtAnalogClock, QwtDialNeedle

Note
  The controls and dials examples shows different types of dials.
  QDial is more similar to QwtKnob than to QwtDial

## Member Enumeration Documentation

enum QwtDial::Mode

Mode controlling whether the needle or the scale is rotating.

Enumerator
RotateNeedle | The needle is rotating.
RotateScale | The needle is fixed, the scales are rotating.

enum QwtDial::Shadow

Frame shadow.

Unfortunately it is not possible to use QFrame::Shadow as a property of a widget that is not derived from QFrame. The following enum is made for the designer only. It is safe to use QFrame::Shadow instead.

Enumerator
Plain | QFrame::Plain.
Raised | QFrame::Raised.
Sunken | QFrame::Sunken.

## Constructor & Destructor Documentation

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

Constructor.

Parameters

  parent | Parent widget

Create a dial widget with no needle. The scale is initialized to [ 0.0, 360.0 ] and 360 steps ( QwtAbstractSlider::setTotalSteps() ). The origin of the scale is at 90°,

The value is set to 0.0.

The default mode is QwtDial::RotateNeedle.

## Member Function Documentation

QRect QwtDial::boundingRect | ( |  | ) | const

Returns
  bounding rectangle of the dial including the frame

See Also
  setLineWidth(), scaleInnerRect(), innerRect()

void QwtDial::changeEvent | ( | QEvent * | event | ) |
| protectedvirtual

Change Event handler

Parameters

  event | Change event

Invalidates internal paint caches if necessary

void QwtDial::drawContents | ( | QPainter * | painter | ) | const
| protectedvirtual

Draw the contents inside the frame.

QPalette::Window is the background color outside of the frame. QPalette::Base is the background color inside the frame. QPalette::WindowText is the background color inside the scale.

Parameters

  painter | Painter

See Also
  boundingRect(), innerRect(), scaleInnerRect(), QWidget::setPalette()

void QwtDial::drawFocusIndicator | ( | QPainter * | painter | ) | const
| protectedvirtual

Draw the focus indicator

Parameters

  painter | Painter

void QwtDial::drawFrame | ( | QPainter * | painter | ) |
| protectedvirtual

Draw the frame around the dial

Parameters

  painter | Painter

See Also
  lineWidth(), frameShadow()

void QwtDial::drawNeedle | ( | QPainter * | painter,
|  | const QPointF & | center,
|  | double | radius,
|  | double | direction,
|  | QPalette::ColorGroup | colorGroup
| ) |  | const
| protectedvirtual

Draw the needle

Parameters

  painter | Painter
  center | Center of the dial
  radius | Length for the needle
  direction | Direction of the needle in degrees, counter clockwise
  colorGroup | ColorGroup

Reimplemented in QwtAnalogClock.

void QwtDial::drawScale | ( | QPainter * | painter,
|  | const QPointF & | center,
|  | double | radius
| ) |  | const
| protectedvirtual

Draw the scale

Parameters

  painter | Painter
  center | Center of the dial
  radius | Radius of the scale

void QwtDial::drawScaleContents | ( | QPainter * | painter,
|  | const QPointF & | center,
|  | double | radius
| ) |  | const
| protectedvirtual

Draw the contents inside the scale

Paints nothing.

Parameters

  painter | Painter
  center | Center of the contents circle
  radius | Radius of the contents circle

Reimplemented in QwtCompass.

QwtDial::Shadow QwtDial::frameShadow | ( |  | ) | const

Returns
  Frame shadow /sa setFrameShadow(), lineWidth(), QFrame::frameShadow()

QRect QwtDial::innerRect | ( |  | ) | const

Returns
  bounding rectangle of the circle inside the frame

See Also
  setLineWidth(), scaleInnerRect(), boundingRect()

void QwtDial::invalidateCache | ( |  | ) |
| protected

Invalidate the internal caches used to speed up repainting

bool QwtDial::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 | the inner circle contains pos

See Also
  scrolledTo()

Implements QwtAbstractSlider.

int QwtDial::lineWidth | ( |  | ) | const

Returns
  Line width of the frame

See Also
  setLineWidth(), frameShadow(), lineWidth()

double QwtDial::maxScaleArc | ( |  | ) | const

Returns
  Upper limit of the scale arc

See Also
  setScaleArc()

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

Returns
  Minimum size hint

See Also
  sizeHint()

double QwtDial::minScaleArc | ( |  | ) | const

Returns
  Lower limit of the scale arc

See Also
  setScaleArc()

QwtDial::Mode QwtDial::mode | ( |  | ) | const

Returns
  Mode of the dial.

See Also
  setMode(), origin(), setScaleArc(), value()

const QwtDialNeedle * QwtDial::needle | ( |  | ) | const

Returns
  needle

See Also
  setNeedle()

QwtDialNeedle * QwtDial::needle | ( |  | ) |

Returns
  needle

See Also
  setNeedle()

double QwtDial::origin | ( |  | ) | const

The origin is the angle where scale and needle is relative to.

Returns
  Origin of the dial

See Also
  setOrigin()

void QwtDial::paintEvent | ( | QPaintEvent * | event | ) |
| protectedvirtual

Paint the dial

Parameters

  event | Paint event

void QwtDial::scaleChange | ( |  | ) |
| protectedvirtual

Invalidate the internal caches and call QwtAbstractSlider::scaleChange()

Reimplemented from QwtAbstractSlider.

QwtRoundScaleDraw * QwtDial::scaleDraw | ( |  | ) |

Returns
  the scale draw

const QwtRoundScaleDraw * QwtDial::scaleDraw | ( |  | ) | const

Returns
  the scale draw

QRect QwtDial::scaleInnerRect | ( |  | ) | const
| virtual

Returns
  rectangle inside the scale

See Also
  setLineWidth(), boundingRect(), innerRect()

double QwtDial::scrolledTo | ( | const QPoint & | pos | ) | const
| protectedvirtual

Determine the value for a new position of the slider handle.

Parameters

  pos | Mouse position

Returns
  Value for the mouse position

See Also
  isScrollPosition()

Implements QwtAbstractSlider.

void QwtDial::setFrameShadow | ( | Shadow | shadow | ) |

Sets the frame shadow value from the frame style.

Parameters

  shadow | Frame shadow

See Also
  setLineWidth(), QFrame::setFrameShadow()

void QwtDial::setLineWidth | ( | int | lineWidth | ) |

Sets the line width of the frame

Parameters

  lineWidth | Line width

See Also
  setFrameShadow()

void QwtDial::setMaxScaleArc | ( | double | max | ) |

Set the upper limit for the scale arc

Parameters

  max | Upper limit of the scale arc

See Also
  setScaleArc(), setMinScaleArc()

void QwtDial::setMinScaleArc | ( | double | min | ) |

Set the lower limit for the scale arc

Parameters

  min | Lower limit of the scale arc

See Also
  setScaleArc(), setMaxScaleArc()

void QwtDial::setMode | ( | Mode | mode | ) |

Change the mode of the dial.

Parameters

  mode | New mode

In case of QwtDial::RotateNeedle the needle is rotating, in case of QwtDial::RotateScale, the needle points to origin() and the scale is rotating.

The default mode is QwtDial::RotateNeedle.

See Also
  mode(), setValue(), setOrigin()

void QwtDial::setNeedle | ( | QwtDialNeedle * | needle | ) |

Set a needle for the dial

Parameters

  needle | Needle

Warning
  The needle will be deleted, when a different needle is set or in ~QwtDial()

void QwtDial::setOrigin | ( | double | origin | ) |
| virtual

Change the origin.

The origin is the angle where scale and needle is relative to.

Parameters

  origin | New origin

See Also
  origin()

void QwtDial::setScaleArc | ( | double | minArc,
|  | double | maxArc
| ) |  |

Change the arc of the scale

Parameters

  minArc | Lower limit
  maxArc | Upper limit

See Also
  minScaleArc(), maxScaleArc()

void QwtDial::setScaleDraw | ( | QwtRoundScaleDraw * | scaleDraw | ) |

Set an individual scale draw

The motivation for setting a scale draw is often to overload QwtRoundScaleDraw::label() to return individual tick labels.

Parameters

  scaleDraw | Scale draw

Warning
  The previous scale draw is deleted

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

Returns
  Size hint

See Also
  minimumSizeHint()

void QwtDial::wheelEvent | ( | QWheelEvent * | event | ) |
| protectedvirtual

Wheel Event handler

Parameters

  event | Wheel event

Reimplemented from QwtAbstractSlider.