QwtColorMap

Section: C Library Functions (3) Updated: 22 Mar 2009 Local index Up

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().