QwtColorMap - Man Page
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
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 QwtColorMap * copy () 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:
- QImage::Format_Indexed8
- QImage::Format_ARGB32
See also:
QwtPlotSpectrogram, QwtScaleWidget
Member Enumeration Documentation
enum QwtColorMap::Format .IP · 2
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 (Formatformat = QwtColorMap::RGB)
Constructor.
QwtColorMap::~QwtColorMap () [virtual]
Destructor.
Member Function Documentation
QColor QwtColorMap::color (const QwtDoubleInterval &interval, doublevalue) 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 QwtDoubleInterval &interval, doublevalue) 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.
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:
interval Range 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, doublevalue) 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, and QwtAlphaColorMap.
Author
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