qwt_knob.h

/* -*- mode: C++ ; c-file-style: "stroustrup" -*- *****************************
 * Qwt Widget Library
 * Copyright (C) 1997   Josef Wilgen
 * Copyright (C) 2002   Uwe Rathmann
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the Qwt License, Version 1.0
 *****************************************************************************/

#ifndef QWT_KNOB_H
#define QWT_KNOB_H

#include "qwt_global.h"
#include "qwt_abstract_slider.h"

class QwtRoundScaleDraw;

/*!
  \brief The Knob Widget

  The QwtKnob widget imitates look and behavior of a volume knob on a radio.
  It looks similar to QDial - not to QwtDial.

  The value range of a knob might be divided into several turns.

  The layout of the knob depends on the knobWidth().

  - width > 0 
    The diameter of the knob is fixed and the knob is aligned
    according to the alignment() flags inside of the contentsRect(). 

  - width <= 0
    The knob is extended to the minimum of width/height of the contentsRect()
    and aligned in the other direction according to alignment().

  Setting a fixed knobWidth() is helpful to align several knobs with different
  scale labels.
  
  \image html knob.png
*/

class QWT_EXPORT QwtKnob: public QwtAbstractSlider
{
    Q_OBJECT

    Q_ENUMS ( KnobStyle MarkerStyle )

    Q_PROPERTY( KnobStyle knobStyle READ knobStyle WRITE setKnobStyle )
    Q_PROPERTY( int knobWidth READ knobWidth WRITE setKnobWidth )
    Q_PROPERTY( Qt::Alignment alignment READ alignment WRITE setAlignment )
    Q_PROPERTY( double totalAngle READ totalAngle WRITE setTotalAngle )
    Q_PROPERTY( int numTurns READ numTurns WRITE setNumTurns )
    Q_PROPERTY( MarkerStyle markerStyle READ markerStyle WRITE setMarkerStyle )
    Q_PROPERTY( int markerSize READ markerSize WRITE setMarkerSize )
    Q_PROPERTY( int borderWidth READ borderWidth WRITE setBorderWidth )

public:
    /*! 
       \brief Style of the knob surface

       Depending on the KnobStyle the surface of the knob is
       filled from the brushes of the widget palette().

       \sa setKnobStyle(), knobStyle()
     */
    enum KnobStyle
    {
        //! Fill the knob with a brush from QPalette::Button.
        Flat,

        //! Build a gradient from QPalette::Midlight and QPalette::Button
        Raised,

        /*! 
          Build a gradient from QPalette::Midlight, QPalette::Button
          and QPalette::Midlight
         */
        Sunken,

        /*! 
          Build a radial gradient from QPalette::Button
          like it is used for QDial in various Qt styles.
         */
        Styled
    };

    /*!
        \brief Marker type
 
        The marker indicates the current value on the knob
        The default setting is a Notch marker.

        \sa setMarkerStyle(), setMarkerSize()
    */
    enum MarkerStyle 
    { 
        //! Don't paint any marker
        NoMarker = -1,

        //! Paint a single tick in QPalette::ButtonText color
        Tick, 

        //! Paint a triangle in QPalette::ButtonText color
        Triangle, 

        //! Paint a circle in QPalette::ButtonText color
        Dot, 

        /*! 
          Draw a raised ellipse with a gradient build from
          QPalette::Light and QPalette::Mid
         */ 
        Nub, 

        /*! 
          Draw a sunken ellipse with a gradient build from
          QPalette::Light and QPalette::Mid
         */ 
        Notch 
    };

    explicit QwtKnob( QWidget* parent = NULL );
    virtual ~QwtKnob();

    void setAlignment( Qt::Alignment );
    Qt::Alignment alignment() const;

    void setKnobWidth( int );
    int knobWidth() const;

    void setNumTurns( int );
    int numTurns() const;

    void setTotalAngle ( double angle );
    double totalAngle() const;

    void setKnobStyle( KnobStyle );
    KnobStyle knobStyle() const;

    void setBorderWidth( int bw );
    int borderWidth() const;

    void setMarkerStyle( MarkerStyle );
    MarkerStyle markerStyle() const;

    void setMarkerSize( int );
    int markerSize() const;

    virtual QSize sizeHint() const;
    virtual QSize minimumSizeHint() const;

    void setScaleDraw( QwtRoundScaleDraw * );

    const QwtRoundScaleDraw *scaleDraw() const;
    QwtRoundScaleDraw *scaleDraw();

    QRect knobRect() const;

protected:
    virtual void paintEvent( QPaintEvent * );
    virtual void changeEvent( QEvent * );

    virtual void drawKnob( QPainter *, const QRectF & ) const;

    virtual void drawFocusIndicator( QPainter * ) const;

    virtual void drawMarker( QPainter *, 
        const QRectF &, double arc ) const;

    virtual double scrolledTo( const QPoint & ) const;
    virtual bool isScrollPosition( const QPoint & ) const;

private:
    class PrivateData;
    PrivateData *d_data;
};

#endif