QwtColorMap Class Reference

QwtColorMap is used to map values into colors. More...

#include <qwt_color_map.h>

Inheritance diagram for QwtColorMap:

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.