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NAME

       QwtColorMap - QwtColorMap is used to map values into colors.

SYNOPSIS

       #include <qwt_color_map.h>

       Inherited by QwtAlphaColorMap, and QwtLinearColorMap.

   Public Types
       enum Format { RGB, Indexed }

   Public Member Functions
       QwtColorMap (Format=QwtColorMap::RGB)
       virtual ~QwtColorMap ()
       Format format () const
       virtual QwtColorMap * copy () const =0
       virtual QRgb rgb (const QwtDoubleInterval &interval, double value)
           const =0
       virtual unsigned char colorIndex (const QwtDoubleInterval &interval,
           double value) const =0
       QColor color (const QwtDoubleInterval &, double value) const
       virtual QVector< QRgb > colorTable (const QwtDoubleInterval &) const

Detailed Description

       QwtColorMap is used to map values into colors.

       For displaying 3D data on a 2D plane the 3rd dimension is often
       displayed using colors, like f.e in a spectrogram.

       Each color map is optimized to return colors for only one of the
       following image formats:

       · QImage::Format_Indexed8

       · QImage::Format_ARGB32

       See also:
           QwtPlotSpectrogram, QwtScaleWidget

Member Enumeration Documentation

   enum QwtColorMap::Format
       · RGB
          The map is intended to map into QRgb values.

       · Indexed
          The map is intended to map into 8 bit values, that are indices into
         the color table.

       See also:
           rgb(), colorIndex(), colorTable()

Constructor & Destructor Documentation

   QwtColorMap::QwtColorMap (Format format = QwtColorMap::RGB)
       Constructor.

   QwtColorMap::~QwtColorMap () [virtual]
       Destructor.

Member Function Documentation

   QColor QwtColorMap::color (const QwtDoubleInterval & interval, double
       value) const [inline]
       Map a value into a color

       Parameters:
           interval Valid interval for values
           value Value

       Returns:
           Color corresponding to value

       Warning:
           This method is slow for Indexed color maps. If it is necessary to
           map many values, its better to get the color table once and find
           the color using colorIndex().

   virtual unsigned char QwtColorMap::colorIndex (const QwtDoubleInterval &
       interval, double value) const [pure virtual]
       Map a value of a given interval into a color index

       Parameters:
           interval Range for the values
           value Value

       Returns:
           color index, corresponding to value

       Implemented in QwtLinearColorMap.

   QwtColorTable QwtColorMap::colorTable (const QwtDoubleInterval & interval)
       const [virtual]
       Build and return a color map of 256 colors

       The color table is needed for rendering indexed images in combination
       with using colorIndex().

       Parameters:
           interval Range for the values

       Returns:
           A color table, that can be used for a QImage

   virtual QwtColorMap* QwtColorMap::copy () const [pure virtual]
       Clone the color map.

       Implemented in QwtLinearColorMap, and QwtAlphaColorMap.

   QwtColorMap::Format QwtColorMap::format () const [inline]
       Returns:
           Intended format of the color map

       See also:
           Format

   virtual QRgb QwtColorMap::rgb (const QwtDoubleInterval & interval, double
       value) const [pure virtual]
       Map a value of a given interval into a rgb value.

       Parameters:
           interval Range for the values
           value Value

       Returns:
           rgb value, corresponding to value

       Implemented in QwtLinearColorMap, and QwtAlphaColorMap.

Author

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