QwtColorMap(3)                 Qwt User's Guide                 QwtColorMap(3)

NAME
       QwtColorMap - QwtColorMap is used to map values into colors.


SYNOPSIS
       #include <qwt_color_map.h>

       Inherited by QwtAlphaColorMap, QwtHueColorMap, QwtLinearColorMap, and
       QwtSaturationValueColorMap.

   Public Types
       enum Format { RGB, Indexed }

   Public Member Functions
       QwtColorMap (Format=QwtColorMap::RGB)
       virtual ~QwtColorMap ()
           Destructor.
       void setFormat (Format)
       virtual QRgb rgb (const QwtInterval &interval, double value) const =0
       virtual uint colorIndex (int numColors, const QwtInterval &interval,
           double value) const
           Map a value of a given interval into a color index.
       QColor color (const QwtInterval &, double value) const
       virtual QVector< QRgb > colorTable (int numColors) const
       virtual QVector< QRgb > colorTable256 () const

   Public Attributes
       Format 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:

       o QImage::Format_Indexed8


       o QImage::Format_ARGB32


       See also
           QwtPlotSpectrogram, QwtScaleWidget

       Definition at line 37 of file qwt_color_map.h.

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
              Map values into 8 bit values, that are used as indexes into the
              color table.

       Indexed color maps are used to generate QImage::Format_Indexed8 images.
       The calculation of the color index is usually faster and the resulting
       image has a lower memory footprint.

       See also
           colorIndex(), colorTable()

       Definition at line 45 of file qwt_color_map.h.

Constructor & Destructor Documentation
   QwtColorMap::QwtColorMap (Format format = QwtColorMap::RGB) [explicit]
       Constructor

       Parameters
           format Format of the color map

       Definition at line 249 of file qwt_color_map.cpp.

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

       Definition at line 248 of file qwt_color_map.h.

   uint QwtColorMap::colorIndex (int numColors, const QwtInterval & interval,
       double value) const [virtual]
       Map a value of a given interval into a color index.

       Parameters
           numColors Number of colors
           interval Range for all values
           value Value to map into a color index

       Returns
           Index, between 0 and numColors - 1, or -1 for an invalid value

       Reimplemented in QwtLinearColorMap.

       Definition at line 278 of file qwt_color_map.cpp.

   QVector< QRgb > QwtColorMap::colorTable (int numColors) const [virtual]
       Build and return a color map of arbitrary number of colors

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

       Parameters
           numColors Number of colors

       Returns
           A color table

       Definition at line 325 of file qwt_color_map.cpp.

   QVector< QRgb > QwtColorMap::colorTable256 () 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().

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

       Definition at line 304 of file qwt_color_map.cpp.

   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 QwtSaturationValueColorMap, QwtHueColorMap,
       QwtAlphaColorMap, and QwtLinearColorMap.

   void QwtColorMap::setFormat (Format format)
       Set the format of the color map

       Parameters
           format Format of the color map

       Definition at line 264 of file qwt_color_map.cpp.

Member Data Documentation
   QwtColorMap::Format QwtColorMap::const [inline]
       Initial value:

       {
           return m_format


       Returns
           Intended format of the color map

       See also
           Format

       Definition at line 67 of file qwt_color_map.h.


Author
       Generated automatically by Doxygen for Qwt User's Guide from the source
       code.

Version 6.2.0                   Sun Jul 18 2021                 QwtColorMap(3)