QwtColorMap Class Reference

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

#include <qwt_colormap.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 (double vMin, double vMax, double value) const =0
	Map a value of a given interval into a RGB value.
virtual uint	colorIndex (int numColors, double vMin, double vMax, double value) const
	Map a value of a given interval into a color index.
QColor	color (double vMin, double vMax, double value) const
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

[in]

format

Format of the color map.

Member Function Documentation

colorIndex()

uint QwtColorMap::colorIndex ( int  numColors, double  vMin, double  vMax, double  value  ) const

virtual

Map a value of a given interval into a color index.

Parameters

[in]	numColors	Number of colors.
[in]	vMin	Minimum of the value interval.
[in]	vMax	Maximum of the value interval.
[in]	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

[in]

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.

rgb()

virtual QRgb QwtColorMap::rgb ( double  vMin, double  vMax, double  value  ) const

pure virtual

Map a value of a given interval into a RGB value.

Implemented in QwtLinearColorMap, QwtAlphaColorMap, QwtHueColorMap, and QwtSaturationValueColorMap.

setFormat()

void QwtColorMap::setFormat

(

Format

format

)

Set the format of the color map.

Parameters

[in]

format

Format of the color map.

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

• /home/runner/work/QWT/QWT/src/core/qwt_colormap.h
• /home/runner/work/QWT/QWT/src/core/qwt_colormap.cpp