Qwt User's Guide  6.1.1
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QwtColorMap Class Referenceabstract

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

#include <qwt_color_map.h>

Inheritance diagram for QwtColorMap:
Inheritance graph
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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:

Member Enumeration Documentation

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
intervalValid interval for values
valueValue
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
intervalRange for the values
valueValue
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
intervalRange 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
intervalRange for the values
valueValue
Returns
RGB value, corresponding to value

Implemented in QwtAlphaColorMap, and QwtLinearColorMap.