QwtColorMap Class Reference

#include <qwt_color_map.h>

Inheritance diagram for QwtColorMap:

List of all members.

Public Types
enum	Format {   RGB,   Indexed }

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

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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

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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()

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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

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 QwtAlphaColorMap, and QwtLinearColorMap.