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 }
	Format for color mapping. More...

Public Member Functions
	QwtColorMap (Format=QwtColorMap::RGB)
	Constructor.
virtual	~QwtColorMap ()
	Destructor.
void	setFormat (Format)
	Set the format of the color map.
Format	format () const
virtual QRgb	rgb (const QwtInterval &interval, double value) const =0
	Map a value of a given interval into a RGB value.
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
	Map a value into a color.
virtual QVector< QRgb >	colorTable (int numColors) const
	Build and return a color map of arbitrary number of colors.
virtual QVector< QRgb >	colorTable256 () const
	Build and return a color map of 256 colors.

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

Format

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()

Constructor & Destructor Documentation

QwtColorMap()

QwtColorMap::QwtColorMap ( Format  format = QwtColorMap::RGB )

explicit

Constructor.

Parameters

format

Format of the color map

Member Function Documentation

color()

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

colorIndex()

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.

colorTable()

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

colorTable256()

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

format()

QwtColorMap::Format QwtColorMap::format ( ) const

inline

Returns

Intended format of the color map

See also

Format

rgb()

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 QwtLinearColorMap, QwtAlphaColorMap, QwtHueColorMap, and QwtSaturationValueColorMap.

setFormat()

void QwtColorMap::setFormat

(

Format

format

)

Set the format of the color map.

Parameters

format

Format of the color map

---

The documentation for this class was generated from the following files:

• /home/runner/work/QWT/QWT/src/qwt_color_map.h
• /home/runner/work/QWT/QWT/src/qwt_color_map.cpp