The Knob Widget. More...

#include <qwt_knob.h>

Inheritance diagram for QwtKnob:

Collaboration diagram for QwtKnob:

Classes
class	PrivateData
Public Types
enum	Symbol { Line, Dot }
Public Member Functions
	QwtKnob (QWidget *parent=NULL)
	QwtKnob (QWidget parent, const char name)
virtual	~QwtKnob ()
	Destructor.
void	setKnobWidth (int w)
	Change the knob's width.
int	knobWidth () const
void	setTotalAngle (double angle)
	Set the total angle by which the knob can be turned.
double	totalAngle () const
void	setBorderWidth (int bw)
	Set the knob's border width.
int	borderWidth () const
void	setSymbol (Symbol)
	Set the symbol of the knob.
Symbol	symbol () const
virtual QSize	sizeHint () const
virtual QSize	minimumSizeHint () const
	Return a minimum size hint.
void	setScaleDraw (QwtRoundScaleDraw *)
const QwtRoundScaleDraw *	scaleDraw () const
QwtRoundScaleDraw *	scaleDraw ()
Protected Member Functions
virtual void	paintEvent (QPaintEvent *e)
virtual void	resizeEvent (QResizeEvent *e)
void	draw (QPainter *p, const QRect &ur)
void	drawKnob (QPainter *p, const QRect &r)
	Draw the knob.
void	drawMarker (QPainter *p, double arc, const QColor &c)
	Draw the marker at the knob's front.
Properties
int	knobWidth
	Return the width of the knob.
int	borderWidth
	Return the border width.
double	totalAngle
	Return the total angle.
Symbol	symbol

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.

Definition at line 34 of file qwt_knob.h.

Member Enumeration Documentation

enum QwtKnob::Symbol

Symbol

See also:: QwtKnob::QwtKnob()

Enumerator:

Line
Dot

Definition at line 49 of file qwt_knob.h.

{ Line, Dot };

Constructor & Destructor Documentation

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

Constructor

Parameters:

parent Parent widget

Definition at line 56 of file qwt_knob.cpp.

                               : 
    QwtAbstractSlider(Qt::Horizontal, parent)
{
    initKnob();
}

QwtKnob::QwtKnob	(	QWidget *	parent,
		const char *	name
	)		`[explicit]`

Constructor

Parameters:

parent	Parent widget
name	Object name

Definition at line 68 of file qwt_knob.cpp.

                                                 : 
    QwtAbstractSlider(Qt::Horizontal, parent)
{
    setName(name);
    initKnob();
}

QwtKnob::~QwtKnob ( ) [virtual]

Destructor.

Definition at line 96 of file qwt_knob.cpp.

{
    delete d_data;
}

Member Function Documentation

int QwtKnob::borderWidth ( ) const

void QwtKnob::draw	(	QPainter *	painter,
		const QRect &	rect
	)		`[protected]`

Repaint the knob

Parameters:

painter	Painter
rect	Update rectangle

Definition at line 387 of file qwt_knob.cpp.

References QwtAbstractScaleDraw::draw(), QwtPainter::drawFocusRect(), drawKnob(), QwtKnob::PrivateData::knobRect, and scaleDraw().

Referenced by paintEvent().

{
    if ( !d_data->knobRect.contains( rect ) ) // event from valueChange()
    {
#if QT_VERSION < 0x040000
        scaleDraw()->draw( painter, colorGroup() );
#else
        scaleDraw()->draw( painter, palette() );
#endif
    }

    drawKnob( painter, d_data->knobRect );

    if ( hasFocus() )
        QwtPainter::drawFocusRect(painter, this);
}

void QwtKnob::drawKnob	(	QPainter *	painter,
		const QRect &	r
	)		`[protected]`

Draw the knob.

Parameters:

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

Definition at line 187 of file qwt_knob.cpp.

References QwtKnob::PrivateData::angle, QwtKnob::PrivateData::borderWidth, drawMarker(), QwtAbstractSlider::isValid(), and qwtMin.

Referenced by draw().

{
#if QT_VERSION < 0x040000
    const QBrush buttonBrush = colorGroup().brush(QColorGroup::Button);
    const QColor buttonTextColor = colorGroup().buttonText();
    const QColor lightColor = colorGroup().light();
    const QColor darkColor = colorGroup().dark();
#else
    const QBrush buttonBrush = palette().brush(QPalette::Button);
    const QColor buttonTextColor = palette().color(QPalette::ButtonText);
    const QColor lightColor = palette().color(QPalette::Light);
    const QColor darkColor = palette().color(QPalette::Dark);
#endif

    const int bw2 = d_data->borderWidth / 2;

    const int radius = (qwtMin(r.width(), r.height()) - bw2) / 2;

    const QRect aRect( 
        r.center().x() - radius, r.center().y() - radius,
        2 * radius, 2 * radius);

    //
    // draw button face
    //
    painter->setBrush(buttonBrush);
    painter->drawEllipse(aRect);

    //
    // draw button shades
    //
    QPen pn;
    pn.setWidth(d_data->borderWidth);

    pn.setColor(lightColor);
    painter->setPen(pn);
    painter->drawArc(aRect, 45*16, 180*16);

    pn.setColor(darkColor);
    painter->setPen(pn);
    painter->drawArc(aRect, 225*16, 180*16);

    //
    // draw marker
    //
    if ( isValid() )
        drawMarker(painter, d_data->angle, buttonTextColor);
}

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

Definition at line 410 of file qwt_knob.cpp.

References QwtKnob::PrivateData::borderWidth, Dot, QwtKnob::PrivateData::dotWidth, QwtKnob::PrivateData::knobRect, Line, M_PI, qwtMax, and QwtKnob::PrivateData::symbol.

Referenced by drawKnob().

{
    const double rarc = arc * M_PI / 180.0;
    const double ca = cos(rarc);
    const double sa = - sin(rarc);

    int radius = d_data->knobRect.width() / 2 - d_data->borderWidth;
    if (radius < 3) 
        radius = 3; 

    const int ym = d_data->knobRect.y() + radius + d_data->borderWidth;
    const int xm = d_data->knobRect.x() + radius + d_data->borderWidth;

    switch (d_data->symbol)
    {
        case Dot:
        {
            p->setBrush(c);
            p->setPen(Qt::NoPen);

            const double rb = double(qwtMax(radius - 4 - d_data->dotWidth / 2, 0));
            p->drawEllipse(xm - qRound(sa * rb) - d_data->dotWidth / 2,
                   ym - qRound(ca * rb) - d_data->dotWidth / 2,
                   d_data->dotWidth, d_data->dotWidth);
            break;
        }
        case Line:
        {
            p->setPen(QPen(c, 2));

            const double rb = qwtMax(double((radius - 4) / 3.0), 0.0);
            const double re = qwtMax(double(radius - 4), 0.0);
            
            p->drawLine ( xm - qRound(sa * rb), ym - qRound(ca * rb),
                xm - qRound(sa * re), ym - qRound(ca * re));
            
            break;
        }
    }
}

int QwtKnob::knobWidth ( ) const

QSize QwtKnob::minimumSizeHint ( ) const [virtual]

Return a minimum size hint.

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

Definition at line 541 of file qwt_knob.cpp.

References QwtRoundScaleDraw::extent(), QwtKnob::PrivateData::knobWidth, QwtKnob::PrivateData::scaleDist, and scaleDraw().

Referenced by sizeHint().

{
    // Add the scale radial thickness to the knobWidth
    const int sh = scaleDraw()->extent( QPen(), font() );
    const int d = 2 * sh + 2 * d_data->scaleDist + d_data->knobWidth;

    return QSize( d, d );
}

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

Repaint the knob

Parameters:

e	Paint event

Definition at line 365 of file qwt_knob.cpp.

References draw(), and QwtPaintBuffer::painter().

{
    const QRect &ur = e->rect();
    if ( ur.isValid() ) 
    {
#if QT_VERSION < 0x040000
        QwtPaintBuffer paintBuffer(this, ur);
        draw(paintBuffer.painter(), ur);
#else
        QPainter painter(this);
        painter.setRenderHint(QPainter::Antialiasing);
        draw(&painter, ur);
#endif
    }
}

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

Qt Resize Event

Definition at line 329 of file qwt_knob.cpp.

{
    layoutKnob( false );
}

const QwtRoundScaleDraw * QwtKnob::scaleDraw ( ) const

Returns:: the scale draw of the knob

See also:: setScaleDraw()

Definition at line 168 of file qwt_knob.cpp.

References QwtAbstractScale::abstractScaleDraw().

Referenced by draw(), minimumSizeHint(), and setTotalAngle().

{
    return (QwtRoundScaleDraw *)abstractScaleDraw();
}

QwtRoundScaleDraw * QwtKnob::scaleDraw ( )

Returns:: the scale draw of the knob

See also:: setScaleDraw()

Definition at line 177 of file qwt_knob.cpp.

References QwtAbstractScale::abstractScaleDraw().

{
    return (QwtRoundScaleDraw *)abstractScaleDraw();
}

void QwtKnob::setBorderWidth ( int bw )

Set the knob's border width.

Parameters:

bw	new border width

Definition at line 473 of file qwt_knob.cpp.

References QwtKnob::PrivateData::borderWidth, and qwtMax.

{
    d_data->borderWidth = qwtMax(bw, 0);
    layoutKnob();
}

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

Definition at line 457 of file qwt_knob.cpp.

References QwtKnob::PrivateData::knobWidth, and qwtMax.

{
    d_data->knobWidth = qwtMax(w,5);
    layoutKnob();
}

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()

Definition at line 158 of file qwt_knob.cpp.

References QwtAbstractScale::setAbstractScaleDraw(), setTotalAngle(), and QwtKnob::PrivateData::totalAngle.

{
    setAbstractScaleDraw(scaleDraw);
    setTotalAngle(d_data->totalAngle);
}

void QwtKnob::setSymbol ( QwtKnob::Symbol s )

Set the symbol of the knob.

See also:: symbol()

Definition at line 105 of file qwt_knob.cpp.

References QwtKnob::PrivateData::symbol.

{
    if ( d_data->symbol != s )
    {
        d_data->symbol = s;
        update();
    }
}

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.

Definition at line 131 of file qwt_knob.cpp.

References scaleDraw(), QwtRoundScaleDraw::setAngleRange(), and QwtKnob::PrivateData::totalAngle.

Referenced by setScaleDraw().

{
    if (angle < 10.0)
       d_data->totalAngle = 10.0;
    else
       d_data->totalAngle = angle;

    scaleDraw()->setAngleRange( -0.5 * d_data->totalAngle, 
        0.5 * d_data->totalAngle);
    layoutKnob();
}

QSize QwtKnob::sizeHint ( ) const [virtual]

Returns:: minimumSizeHint()

Definition at line 531 of file qwt_knob.cpp.

References minimumSizeHint().

{
    return minimumSizeHint();
}

Symbol QwtKnob::symbol ( ) const

double QwtKnob::totalAngle ( ) const

Property Documentation

int QwtKnob::borderWidth [read, write]

Return the border width.

Definition at line 39 of file qwt_knob.h.

int QwtKnob::knobWidth [read, write]

Return the width of the knob.

Definition at line 38 of file qwt_knob.h.

QwtKnob::Symbol QwtKnob::symbol [read, write]

Returns:: symbol of the knob

See also:: setSymbol()

Definition at line 41 of file qwt_knob.h.

double QwtKnob::totalAngle [read, write]

Return the total angle.

Definition at line 40 of file qwt_knob.h.

The documentation for this class was generated from the following files:

QwtKnob Class Reference

Classes

Public Types

Public Member Functions

Protected Member Functions

Properties

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Property Documentation