QwtColorMap(3) Qwt User's Guide QwtColorMap(3)

QwtColorMap - QwtColorMap is used to map values into colors.

#include <qwt_color_map.h>

Inherited by QwtAlphaColorMap, QwtHueColorMap, QwtLinearColorMap, and QwtSaturationValueColorMap.


enum Format { RGB, Indexed }


QwtColorMap (Format=QwtColorMap::RGB)
virtual ~QwtColorMap ()
Destructor. void setFormat (Format)
virtual QRgb rgb (const QwtInterval &interval, double value) const =0
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
virtual QVector< QRgb > colorTable (int numColors) const
virtual QVector< QRgb > colorTable256 () const


Format const

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

Definition at line 37 of file qwt_color_map.h.

Format for color mapping

See also

rgb(), colorIndex(), colorTable()

Enumerator

The map is intended to map into RGB values.
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()

Definition at line 45 of file qwt_color_map.h.

Constructor

Parameters

format Format of the color map

Definition at line 249 of file qwt_color_map.cpp.

Map a value into a color

Parameters

interval Valid interval for values
value Value

Returns

Color corresponding to value

Definition at line 248 of file qwt_color_map.h.

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.

Definition at line 278 of file qwt_color_map.cpp.

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

Definition at line 325 of file qwt_color_map.cpp.

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

Definition at line 304 of file qwt_color_map.cpp.

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 QwtSaturationValueColorMap, QwtHueColorMap, QwtAlphaColorMap, and QwtLinearColorMap.

Set the format of the color map

Parameters

format Format of the color map

Definition at line 264 of file qwt_color_map.cpp.

QwtColorMap::Format QwtColorMap::const [inline]

Initial value:

{

return m_format

Returns

Intended format of the color map

See also

Format

Definition at line 67 of file qwt_color_map.h.

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Sun Jul 18 2021 Version 6.2.0