qwt_dial_needle.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_DIAL_NEEDLE_H
#define QWT_DIAL_NEEDLE_H 1

#include "qwt_global.h"
#include <qpalette.h>

class QPainter;
class QPoint;

/*!
  \brief Base class for needles that can be used in a QwtDial.

  QwtDialNeedle is a pointer that indicates a value by pointing
  to a specific direction.

  \sa QwtDial, QwtCompass
*/

class QWT_EXPORT QwtDialNeedle
{
public:
    QwtDialNeedle();
    virtual ~QwtDialNeedle();

    virtual void setPalette( const QPalette & );
    const QPalette &palette() const;

    virtual void draw( QPainter *painter, const QPointF &center,
        double length, double direction, 
        QPalette::ColorGroup = QPalette::Active ) const;

protected:
    /*!
      \brief Draw the needle

      The origin of the needle is at position (0.0, 0.0 )
      pointing in direction 0.0 ( = east ). 

      The painter is already initialized with translation and 
      rotation.

      \param painter Painter
      \param length Length of the needle
      \param colorGroup Color group, used for painting

      \sa setPalette(), palette()
    */
    virtual void drawNeedle( QPainter *painter, 
        double length, QPalette::ColorGroup colorGroup ) const = 0;

    virtual void drawKnob( QPainter *, double width, 
        const QBrush &, bool sunken ) const;

private:
    QPalette d_palette;
};

/*!
  \brief A needle for dial widgets

  The following colors are used:

  - QPalette::Mid\n
    Pointer
  - QPalette::Base\n
    Knob

  \sa QwtDial, QwtCompass
*/

class QWT_EXPORT QwtDialSimpleNeedle: public QwtDialNeedle
{
public:
    //! Style of the needle
    enum Style
    {
        //! Arrow
        Arrow,

        //! A straight line from the center
        Ray
    };

    QwtDialSimpleNeedle( Style, bool hasKnob = true,
        const QColor &mid = Qt::gray, const QColor &base = Qt::darkGray );

    void setWidth( double width );
    double width() const;

protected:
    virtual void drawNeedle( QPainter *, double length,
        QPalette::ColorGroup ) const;

private:
    Style d_style;
    bool d_hasKnob;
    double d_width;
};

/*!
  \brief A magnet needle for compass widgets

  A magnet needle points to two opposite directions indicating
  north and south.

  The following colors are used:
  - QPalette::Light\n
    Used for pointing south
  - QPalette::Dark\n
    Used for pointing north
  - QPalette::Base\n
    Knob (ThinStyle only)

  \sa QwtDial, QwtCompass
*/

class QWT_EXPORT QwtCompassMagnetNeedle: public QwtDialNeedle
{
public:
    //! Style of the needle
    enum Style
    {
        //! A needle with a triangular shape
        TriangleStyle,

        //! A thin needle 
        ThinStyle
    };

    QwtCompassMagnetNeedle( Style = TriangleStyle,
        const QColor &light = Qt::white, const QColor &dark = Qt::red );

protected:
    virtual void drawNeedle( QPainter *, 
        double length, QPalette::ColorGroup ) const;

private:
    Style d_style;
};

/*!
  \brief An indicator for the wind direction

  QwtCompassWindArrow shows the direction where the wind comes from.

  - QPalette::Light\n
    Used for Style1, or the light half of Style2
  - QPalette::Dark\n
    Used for the dark half of Style2

  \sa QwtDial, QwtCompass
*/

class QWT_EXPORT QwtCompassWindArrow: public QwtDialNeedle
{
public:
    //! Style of the arrow
    enum Style
    {
        //! A needle pointing to the center
        Style1,

        //! A needle pointing to the center
        Style2
    };

    QwtCompassWindArrow( Style, const QColor &light = Qt::white,
        const QColor &dark = Qt::gray );

protected:
    virtual void drawNeedle( QPainter *, 
        double length, QPalette::ColorGroup ) const;

private:
    Style d_style;
};

#endif