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NAME

       QwtAbstractScaleDraw - A abstract base class for drawing scales.

SYNOPSIS

       #include <qwt_abstract_scale_draw.h>

       Inherited by QwtRoundScaleDraw, and QwtScaleDraw.

   Public Types
       enum ScaleComponent { Backbone = 0x01, Ticks = 0x02, Labels = 0x04 }
       typedef QFlags< ScaleComponent > ScaleComponents
           Scale components.

   Public Member Functions
       QwtAbstractScaleDraw ()
           Constructor.
       virtual ~QwtAbstractScaleDraw ()
           Destructor.
       void setScaleDiv (const QwtScaleDiv &)
       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)
           Set the spacing between tick and labels.
       double spacing () const
           Get the spacing.
       void setPenWidth (int width)
           Specify the width of the scale pen.
       int penWidth () const
       virtual void draw (QPainter *, const QPalette &) const
           Draw the scale.
       virtual QwtText label (double) const
           Convert a value into its representing label.
       virtual double extent (const QFont &font) const =0
       void setMinimumExtent (double)
           Set a minimum for the extent.
       double minimumExtent () const

   Protected Member Functions
       virtual void drawTick (QPainter *painter, double value, double len) const =0
       virtual void drawBackbone (QPainter *painter) const =0
       virtual void drawLabel (QPainter *painter, double value) const =0
       void invalidateCache ()
       const QwtText & tickLabel (const QFont &, double value) const
           Convert a value into its representing label and cache it.

Detailed Description

       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.

Member Enumeration Documentation

   enum QwtAbstractScaleDraw::ScaleComponent
       Components of a scale

       See also:
           enableComponent(), hasComponent

       Enumerator

       Backbone
              Backbone = the line where the ticks are located.

       Ticks  Ticks.

       Labels Labels.

Constructor & Destructor Documentation

   QwtAbstractScaleDraw::QwtAbstractScaleDraw ()
       Constructor. The range of the scale is initialized to [0, 100], The spacing (distance
       between ticks and labels) is set to 4, the tick lengths are set to 4,6 and 8 pixels

Member Function Documentation

   void QwtAbstractScaleDraw::draw (QPainter * painter, const QPalette & palette) const [virtual]
       Draw the scale.

       Parameters:
           painter The painter
           palette Palette, text color is used for the labels, foreground color for ticks and
           backbone

   virtual void QwtAbstractScaleDraw::drawBackbone (QPainter * painter) const [protected],  [pure
       virtual]
       Draws the baseline of the scale

       Parameters:
           painter Painter

       See also:
           drawTick(), drawLabel()

       Implemented in QwtScaleDraw, and QwtRoundScaleDraw.

   virtual void QwtAbstractScaleDraw::drawLabel (QPainter * painter, double value) const
       [protected],  [pure virtual]
       Draws the label for a major scale tick

       Parameters:
           painter Painter
           value Value

       See also:
           drawTick(), drawBackbone()

       Implemented in QwtScaleDraw, and QwtRoundScaleDraw.

   virtual void QwtAbstractScaleDraw::drawTick (QPainter * painter, double value, double len)
       const [protected],  [pure virtual]
       Draw a tick

       Parameters:
           painter Painter
           value Value of the tick
           len Length of the tick

       See also:
           drawBackbone(), drawLabel()

       Implemented in QwtScaleDraw, and QwtRoundScaleDraw.

   void QwtAbstractScaleDraw::enableComponent (ScaleComponent component, bool enable = true)
       En/Disable a component of the scale

       Parameters:
           component Scale component
           enable On/Off

       See also:
           hasComponent()

   virtual double QwtAbstractScaleDraw::extent (const QFont & font) const [pure virtual]
       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.

       Parameters:
           font Font used for drawing the tick labels

       Returns:
           Number of pixels

       See also:
           setMinimumExtent(), minimumExtent()

       Implemented in QwtScaleDraw, and QwtRoundScaleDraw.

   bool QwtAbstractScaleDraw::hasComponent (ScaleComponent component) const
       Check if a component is enabled

       Parameters:
           component Component type

       Returns:
           true, when component is enabled

       See also:
           enableComponent()

   void QwtAbstractScaleDraw::invalidateCache () [protected]
       Invalidate the cache used by tickLabel()

       The cache is invalidated, when a new QwtScaleDiv is set. If the labels need to be changed.
       while the same QwtScaleDiv is set, invalidateCache() needs to be called manually.

   QwtText QwtAbstractScaleDraw::label (double value) const [virtual]
       Convert a value into its representing label. The value is converted to a plain text using
       QLocale().toString(value). This method is often overloaded by applications to have
       individual labels.

       Parameters:
           value Value

       Returns:
           Label string.

       Reimplemented in QwtDateScaleDraw, and QwtCompassScaleDraw.

   double QwtAbstractScaleDraw::maxTickLength () const
       Returns:
           Length of the longest tick

       Useful for layout calculations

       See also:
           tickLength(), setTickLength()

   double QwtAbstractScaleDraw::minimumExtent () const
       Get the minimum extent

       Returns:
           Minimum extent

       See also:
           extent(), setMinimumExtent()

   int QwtAbstractScaleDraw::penWidth () const
       Returns:
           Scale pen width

       See also:
           setPenWidth()

   const QwtScaleDiv & QwtAbstractScaleDraw::scaleDiv () const
       Returns:
           scale division

   const QwtScaleMap & QwtAbstractScaleDraw::scaleMap () const
       Returns:
           Map how to translate between scale and pixel values

   QwtScaleMap & QwtAbstractScaleDraw::scaleMap ()
       Returns:
           Map how to translate between scale and pixel values

   void QwtAbstractScaleDraw::setMinimumExtent (double minExtent)
       Set a minimum for the extent. The extent is calculated from the components of the scale
       draw. In situations, where the labels are changing and the layout depends on the extent
       (f.e scrolling a scale), setting an upper limit as minimum extent will avoid jumps of the
       layout.

       Parameters:
           minExtent Minimum extent

       See also:
           extent(), minimumExtent()

   void QwtAbstractScaleDraw::setPenWidth (int width)
       Specify the width of the scale pen.

       Parameters:
           width Pen width

       See also:
           penWidth()

   void QwtAbstractScaleDraw::setScaleDiv (const QwtScaleDiv & scaleDiv)
       Change the scale division

       Parameters:
           scaleDiv New scale division

   void QwtAbstractScaleDraw::setSpacing (double spacing)
       Set the spacing between tick and labels. The spacing is the distance between ticks and
       labels. The default spacing is 4 pixels.

       Parameters:
           spacing Spacing

       See also:
           spacing()

   void QwtAbstractScaleDraw::setTickLength (QwtScaleDiv::TickType tickType, double length)
       Set the length of the ticks

       Parameters:
           tickType Tick type
           length New length

       Warning:
           the length is limited to [0..1000]

   void QwtAbstractScaleDraw::setTransformation (QwtTransform * transformation)
       Change the transformation of the scale

       Parameters:
           transformation New scale transformation

   double QwtAbstractScaleDraw::spacing () const
       Get the spacing. The spacing is the distance between ticks and labels. The default spacing
       is 4 pixels.

       Returns:
           Spacing

       See also:
           setSpacing()

   const QwtText & QwtAbstractScaleDraw::tickLabel (const QFont & font, double value) const
       [protected]
       Convert a value into its representing label and cache it. The conversion between value and
       label is called very often in the layout and painting code. Unfortunately the calculation
       of the label sizes might be slow (really slow for rich text in Qt4), so it's necessary to
       cache the labels.

       Parameters:
           font Font
           value Value

       Returns:
           Tick label

   double QwtAbstractScaleDraw::tickLength (QwtScaleDiv::TickType tickType) const
       Returns:
           Length of the ticks

       See also:
           setTickLength(), maxTickLength()

Author

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