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)
           Constructor.
       virtual ~QwtColorMap ()
           Destructor.
       Format format () const
       virtual QRgb rgb (const QwtInterval &interval, double value) const =0
       virtual unsigned char colorIndex (const QwtInterval &interval, double value) const =0
       QColor color (const QwtInterval &, double value) const
       virtual QVector< QRgb > colorTable (const QwtInterval &) 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
       Format for color mapping

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

       Enumerator

       RGB    The map is intended to map into RGB values.

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

Member Function Documentation

   QColor QwtColorMap::color (const QwtInterval & 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 QwtInterval & 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.

   QVector< QRgb > QwtColorMap::colorTable (const QwtInterval & 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

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

       See also:
           Format

   virtual QRgb QwtColorMap::rgb (const QwtInterval & 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 QwtAlphaColorMap, and QwtLinearColorMap.

Author

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