QwtDial - QwtDial class provides a rounded range control.

NAME

QwtDial − QwtDial class provides a rounded range control.

SYNOPSIS

#include <qwt_dial.h>

Inherits QwtAbstractSlider.

Inherited by QwtAnalogClock, and QwtCompass.

Public Types

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

Public Member Functions

QwtDial (QWidget *parent=NULL)
Constructor.
virtual ˜QwtDial ()
Destructor.
void setFrameShadow (Shadow)
Shadow frameShadow () const
void setLineWidth (int)
int lineWidth () const
void setMode (Mode)
Change the mode of the dial.
Mode mode () const
void setScaleArc (double minArc, double maxArc)
void setMinScaleArc (double)
double minScaleArc () const
void setMaxScaleArc (double)
double maxScaleArc () const
virtual void setOrigin (double)
Change the origin.
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 override
virtual QSize minimumSizeHint () const override
void setScaleDraw (QwtRoundScaleDraw *)
QwtRoundScaleDraw * scaleDraw ()
const QwtRoundScaleDraw * scaleDraw () const

Public Member Functions inherited from QwtAbstractSlider

QwtAbstractSlider (QWidget *parent=NULL)
Constructor.
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.
uint totalSteps () const
void setSingleSteps (uint)
Set the number of steps for a single increment.
uint singleSteps () const
void setPageSteps (uint)
Set the number of steps for a page increment.
uint pageSteps () const
void setStepAlignment (bool)
Enable step alignment.
bool stepAlignment () const
void setTracking (bool)
Enables or disables tracking.
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.
void setScale (const QwtInterval &)
Specify a scale.
void setScale (const QwtScaleDiv &)
Specify a scale.
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.
double scaleStepSize () const
void setScaleMaxMajor (int ticks)
Set the maximum number of major tick intervals.
int scaleMaxMinor () const
void setScaleMaxMinor (int ticks)
Set the maximum number of minor tick intervals.
int scaleMaxMajor () const
void setScaleEngine (QwtScaleEngine *)
Set a scale engine.
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 *) override
virtual void paintEvent (QPaintEvent *) override
virtual void changeEvent (QEvent *) override
virtual void drawFrame (QPainter *)
virtual void drawContents (QPainter *) const
Draw the contents inside the frame.
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 override
Determine the value for a new position of the slider handle.
virtual bool isScrollPosition (const QPoint &) const override
Determine what to do when the user presses a mouse button.
virtual void sliderChange () override
Calling update()
virtual void scaleChange () override

Protected Member Functions inherited from QwtAbstractSlider

virtual void mousePressEvent (QMouseEvent *) override
virtual void mouseReleaseEvent (QMouseEvent *) override
virtual void mouseMoveEvent (QMouseEvent *) override
virtual void keyPressEvent (QKeyEvent *) override
void incrementValue (int stepCount)
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.
const QwtAbstractScaleDraw * abstractScaleDraw () const
QwtAbstractScaleDraw * abstractScaleDraw ()
void updateScaleDraw ()

Additional Inherited Members

Public Slots inherited from QwtAbstractSlider

void setValue (double value)

Signals inherited from QwtAbstractSlider

void valueChanged (double value)
Notify a change of value.
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

Definition at line 50 of file qwt_dial.h.

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.

Definition at line 86 of file qwt_dial.h.

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.

Definition at line 73 of file qwt_dial.h.

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 90Â°,

The value is set to 0.0.

The default mode is QwtDial::RotateNeedle.

Definition at line 124 of file qwt_dial.cpp.

QwtDial::˜QwtDial () [virtual]

Destructor.

Definition at line 159 of file qwt_dial.cpp.

Member Function Documentation

QRect QwtDial::boundingRect () const

Returns

bounding rectangle of the dial including the frame

See also

setLineWidth(), scaleInnerRect(), innerRect()

Definition at line 234 of file qwt_dial.cpp.

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

Change Event handler

Parameters

event Change event

Invalidates internal paint caches if necessary

Reimplemented from QwtAbstractScale.

Definition at line 804 of file qwt_dial.cpp.

void QwtDial::drawContents (QPainter * painter) const [protected],[virtual]

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()

Definition at line 391 of file qwt_dial.cpp.

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

Draw the focus indicator

Parameters

painter Painter

Definition at line 362 of file qwt_dial.cpp.

void QwtDial::drawFrame (QPainter * painter) [protected], [virtual]

Draw the frame around the dial

Parameters

painter Painter

See also

lineWidth(), frameShadow()

Definition at line 373 of file qwt_dial.cpp.

void QwtDial::drawNeedle (QPainter * painter, const QPointF & center,double radius, double direction, QPalette::ColorGroup colorGroup) const[protected], [virtual]

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.

Definition at line 438 of file qwt_dial.cpp.

void QwtDial::drawScale (QPainter * painter, const QPointF & center, doubleradius) const [protected], [virtual]

Draw the scale

Parameters

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

Definition at line 475 of file qwt_dial.cpp.

void QwtDial::drawScaleContents (QPainter * painter, const QPointF &center, double radius) const [protected], [virtual]

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.

Definition at line 506 of file qwt_dial.cpp.

QwtDial::Shadow QwtDial::frameShadow () const

Returns

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

Definition at line 186 of file qwt_dial.cpp.

QRect QwtDial::innerRect () const

Returns

bounding rectangle of the circle inside the frame

See also

setLineWidth(), scaleInnerRect(), boundingRect()

Definition at line 224 of file qwt_dial.cpp.

void QwtDial::invalidateCache () [protected]

Invalidate the internal caches used to speed up repainting

Definition at line 301 of file qwt_dial.cpp.

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

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.

Definition at line 721 of file qwt_dial.cpp.

int QwtDial::lineWidth () const

Returns

Line width of the frame

See also

setLineWidth(), frameShadow(), lineWidth()

Definition at line 215 of file qwt_dial.cpp.

double QwtDial::maxScaleArc () const

Returns

Upper limit of the scale arc

See also

setScaleArc()

Definition at line 647 of file qwt_dial.cpp.

QSize QwtDial::minimumSizeHint () const [override], [virtual]

Returns

Minimum size hint

See also

sizeHint()

Definition at line 702 of file qwt_dial.cpp.

double QwtDial::minScaleArc () const

Returns

Lower limit of the scale arc

See also

setScaleArc()

Definition at line 627 of file qwt_dial.cpp.

QwtDial::Mode QwtDial::mode () const

Returns

Mode of the dial.

See also

setMode(), origin(), setScaleArc(), value()

Definition at line 293 of file qwt_dial.cpp.

QwtDialNeedle * QwtDial::needle ()

Returns

needle

See also

setNeedle()

Definition at line 547 of file qwt_dial.cpp.

const QwtDialNeedle * QwtDial::needle () const

Returns

needle

See also

setNeedle()

Definition at line 538 of file qwt_dial.cpp.

double QwtDial::origin () const

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

Returns

Origin of the dial

See also

setOrigin()

Definition at line 674 of file qwt_dial.cpp.

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

Paint the dial

Parameters

event Paint event

Definition at line 310 of file qwt_dial.cpp.

void QwtDial::scaleChange () [override], [protected], [virtual]

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

Reimplemented from QwtAbstractSlider.

Definition at line 855 of file qwt_dial.cpp.

QwtRoundScaleDraw * QwtDial::scaleDraw ()

Returns

the scale draw

Definition at line 553 of file qwt_dial.cpp.

const QwtRoundScaleDraw * QwtDial::scaleDraw () const

Returns

the scale draw

Definition at line 559 of file qwt_dial.cpp.

QRect QwtDial::scaleInnerRect () const [virtual]

Returns

rectangle inside the scale

See also

setLineWidth(), boundingRect(), innerRect()

Definition at line 250 of file qwt_dial.cpp.

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

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.

Definition at line 751 of file qwt_dial.cpp.

void QwtDial::setFrameShadow (Shadow shadow)

Sets the frame shadow value from the frame style.

Parameters

shadow Frame shadow

See also

setLineWidth(), QFrame::setFrameShadow()

Definition at line 170 of file qwt_dial.cpp.

void QwtDial::setLineWidth (int lineWidth)

Sets the line width of the frame

Parameters

lineWidth Line width

See also

setFrameShadow()

Definition at line 197 of file qwt_dial.cpp.

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()

Definition at line 638 of file qwt_dial.cpp.

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()

Definition at line 618 of file qwt_dial.cpp.

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()

Definition at line 278 of file qwt_dial.cpp.

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()

Definition at line 522 of file qwt_dial.cpp.

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()

Definition at line 660 of file qwt_dial.cpp.

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

Change the arc of the scale

Parameters

minArc Lower limit
maxArc Upper limit

See also

minScaleArc(), maxScaleArc()

Definition at line 588 of file qwt_dial.cpp.

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

Definition at line 574 of file qwt_dial.cpp.

QSize QwtDial::sizeHint () const [override], [virtual]

Returns

Size hint

See also

minimumSizeHint()

Definition at line 683 of file qwt_dial.cpp.

void QwtDial::sliderChange () [override], [protected], [virtual]

Calling update()

Reimplemented from QwtAbstractSlider.

Definition at line 861 of file qwt_dial.cpp.

void QwtDial::wheelEvent (QWheelEvent * event) [override], [protected],[virtual]

Wheel Event handler

Parameters

event Wheel event

Reimplemented from QwtAbstractSlider.

Definition at line 829 of file qwt_dial.cpp.

Author

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Updated 2026-06-01 - jenkler.se | uex.se