qwt_abstract_scale_draw.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_ABSTRACT_SCALE_DRAW_H
#define QWT_ABSTRACT_SCALE_DRAW_H

#include "qwt_global.h"
#include "qwt_scale_div.h"
#include "qwt_text.h"

class QPalette;
class QPainter;
class QFont;
class QwtTransform;
class QwtScaleMap;

/*!
  \brief A abstract base class for drawing scales

  QwtAbstractScaleDraw can be used to draw linear or logarithmic scales.

  After a scale division has been specified as a QwtScaleDiv object
  using setScaleDiv(), the scale can be drawn with the draw() member.
*/
class QWT_EXPORT QwtAbstractScaleDraw
{
public:

    /*!
       Components of a scale
       \sa enableComponent(), hasComponent
    */
    enum ScaleComponent
    {
        //! Backbone = the line where the ticks are located
        Backbone = 0x01,

        //! Ticks
        Ticks = 0x02,

        //! Labels
        Labels = 0x04
    };

    //! Scale components
    typedef QFlags<ScaleComponent> ScaleComponents;

    QwtAbstractScaleDraw();
    virtual ~QwtAbstractScaleDraw();

    void setScaleDiv( const QwtScaleDiv &s );
    const QwtScaleDiv& scaleDiv() const;

    void setTransformation( QwtTransform * );
    const QwtScaleMap &scaleMap() const;
    QwtScaleMap &scaleMap();

    void enableComponent( ScaleComponent, bool enable = true );
    bool hasComponent( ScaleComponent ) const;

    void setTickLength( QwtScaleDiv::TickType, double length );
    double tickLength( QwtScaleDiv::TickType ) const;
    double maxTickLength() const;

    void setSpacing( double margin );
    double spacing() const;

    void setPenWidth( int width );
    int penWidth() const;

    virtual void draw( QPainter *, const QPalette & ) const;

    virtual QwtText label( double ) const;

    /*!
      Calculate the extent

      The extent is the distance from the baseline to the outermost
      pixel of the scale draw in opposite to its orientation.
      It is at least minimumExtent() pixels.

      \param font Font used for drawing the tick labels
      \return Number of pixels

      \sa setMinimumExtent(), minimumExtent()
    */
    virtual double extent( const QFont &font ) const = 0;

    void setMinimumExtent( double );
    double minimumExtent() const;

protected:
    /*!
       Draw a tick

       \param painter Painter
       \param value Value of the tick
       \param len Length of the tick

       \sa drawBackbone(), drawLabel()
    */
    virtual void drawTick( QPainter *painter, double value, double len ) const = 0;

    /*!
      Draws the baseline of the scale
      \param painter Painter

      \sa drawTick(), drawLabel()
    */
    virtual void drawBackbone( QPainter *painter ) const = 0;

    /*!
        Draws the label for a major scale tick

        \param painter Painter
        \param value Value

        \sa drawTick(), drawBackbone()
    */
    virtual void drawLabel( QPainter *painter, double value ) const = 0;

    void invalidateCache();
    const QwtText &tickLabel( const QFont &, double value ) const;

private:
    QwtAbstractScaleDraw( const QwtAbstractScaleDraw & );
    QwtAbstractScaleDraw &operator=( const QwtAbstractScaleDraw & );

    class PrivateData;
    PrivateData *d_data;
};

Q_DECLARE_OPERATORS_FOR_FLAGS( QwtAbstractScaleDraw::ScaleComponents )

#endif