Man page - qwtcolormap(3)

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Manual

QwtColorMap

NAME
SYNOPSIS
Public Types
Public Member Functions
Detailed Description
Member Enumeration Documentation
enum QwtColorMap::Format
Member Function Documentation
QColor QwtColorMap::color (const QwtInterval & interval, double value)const [inline]
virtual unsigned char QwtColorMap::colorIndex (const QwtInterval &interval, double value) const [pure virtual]
QVector< QRgb > QwtColorMap::colorTable (const QwtInterval & interval)const [virtual]
QwtColorMap::Format QwtColorMap::format () const [inline]
virtual QRgb QwtColorMap::rgb (const QwtInterval & interval, double value)const [pure virtual]
Author

NAME

QwtColorMap - QwtColorMap is used to map values into colors.

SYNOPSIS

#include <qwt_color_map.h>

Inherited by QwtAlphaColorMap , and QwtLinearColorMap .

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 .

Author

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