Qwt User's Guide 5.2.2
Public Types | Public Member Functions

QwtColorMap Class Reference

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

#include <qwt_color_map.h>

Inheritance diagram for QwtColorMap:
Inheritance graph
[legend]

List of all members.

Public Types

enum  Format {
  RGB,
  Indexed
}

Public Member Functions

QColor color (const QwtDoubleInterval &, double value) const
virtual unsigned char colorIndex (const QwtDoubleInterval &interval, double value) const =0
virtual QVector< QRgb > colorTable (const QwtDoubleInterval &) const
virtual QwtColorMapcopy () const =0
Format format () const
 QwtColorMap (Format=QwtColorMap::RGB)
virtual QRgb rgb (const QwtDoubleInterval &interval, double value) const =0
virtual ~QwtColorMap ()

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:

See also:
QwtPlotSpectrogram, QwtScaleWidget

Member Enumeration Documentation

  • RGB
    The map is intended to map into QRgb values.
  • Indexed
    The map is intended to map into 8 bit values, that are indices into the color table.
See also:
rgb(), colorIndex(), colorTable()

Constructor & Destructor Documentation

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

Constructor.

QwtColorMap::~QwtColorMap ( ) [virtual]

Destructor.


Member Function Documentation

QColor QwtColorMap::color ( const QwtDoubleInterval 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 QwtDoubleInterval 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.

QwtColorTable QwtColorMap::colorTable ( const QwtDoubleInterval 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
virtual QwtColorMap* QwtColorMap::copy ( ) const [pure virtual]

Clone the color map.

Implemented in QwtLinearColorMap, and QwtAlphaColorMap.

QwtColorMap::Format QwtColorMap::format ( ) const [inline]
Returns:
Intended format of the color map
See also:
Format
virtual QRgb QwtColorMap::rgb ( const QwtDoubleInterval 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 QwtLinearColorMap, and QwtAlphaColorMap.