QwtLinearColorMap man page

QwtLinearColorMap —

QwtLinearColorMap builds a color map from color stops.

Synopsis

#include <qwt_color_map.h>

Inherits QwtColorMap.

Public Types

enum Format { RGB, Indexed }

enum Mode { FixedColors, ScaledColors }

Public Member Functions

void addColorStop (double value, const QColor &)

QColor color (const QwtDoubleInterval &, double value) const

QColor color1 () const

QColor color2 () const

virtual unsigned char colorIndex (const QwtDoubleInterval &, double value) const

QwtArray< double > colorStops () const

virtual QVector< QRgb > colorTable (const QwtDoubleInterval &) const

virtual QwtColorMap * copy () const

Format format () const

Mode mode () const

QwtLinearColorMap & operator= (const QwtLinearColorMap &)

QwtLinearColorMap (const QColor &from, const QColor &to, QwtColorMap::Format=QwtColorMap::RGB)

QwtLinearColorMap (QwtColorMap::Format=QwtColorMap::RGB)

QwtLinearColorMap (const QwtLinearColorMap &)

virtual QRgb rgb (const QwtDoubleInterval &, double value) const

void setColorInterval (const QColor &color1, const QColor &color2)

void setMode (Mode)

virtual ~QwtLinearColorMap ()

Detailed Description

QwtLinearColorMap builds a color map from color stops.

A color stop is a color at a specific position. The valid range for the positions is [0.0, 1.0]. When mapping a value into a color it is translated into this interval. If mode() == FixedColors the color is calculated from the next lower color stop. If mode() == ScaledColors the color is calculated by interpolating the colors of the adjacent stops.

Member Enumeration Documentation

enum QwtColorMap::Format [inherited] .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()

enum QwtLinearColorMap::Mode Mode of color map

See also:

setMode(), mode()

Constructor & Destructor Documentation

QwtLinearColorMap::QwtLinearColorMap (QwtColorMap::Formatformat = QwtColorMap::RGB) Build a color map with two stops at 0.0 and 1.0. The color at 0.0 is Qt::blue, at 1.0 it is Qt::yellow.

Parameters:

format Preferred format of the color map

QwtLinearColorMap::QwtLinearColorMap (const QColor &color1, const QColor &color2, QwtColorMap::Formatformat = QwtColorMap::RGB) Build a color map with two stops at 0.0 and 1.0.

Parameters:

color1 Color used for the minimum value of the value interval
color2 Color used for the maximum value of the value interval
format Preferred format of the coor map

QwtLinearColorMap::QwtLinearColorMap (const QwtLinearColorMap &other)

Copy constructor.

QwtLinearColorMap::~QwtLinearColorMap () [virtual]

Destructor.

Member Function Documentation

void QwtLinearColorMap::addColorStop (doublevalue, const QColor &color) Add a color stop

The value has to be in the range [0.0, 1.0]. F.e. a stop at position 17.0 for a range [10.0,20.0] must be passed as: (17.0 - 10.0) / (20.0 - 10.0)

Parameters:

value Value between [0.0, 1.0]
color Color stop

QColor QwtColorMap::color (const QwtDoubleInterval &interval, doublevalue) const [inline, inherited] 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().

QColor QwtLinearColorMap::color1 () const Returns

the first color of the color range

See also:

setColorInterval()

QColor QwtLinearColorMap::color2 () const Returns

the second color of the color range

See also:

setColorInterval()

unsigned char QwtLinearColorMap::colorIndex (const QwtDoubleInterval &interval, doublevalue) const [virtual] Map a value of a given interval into a color index, between 0 and 255

Parameters:

interval Range for all values
value Value to map into a color index

Implements QwtColorMap.

QwtArray< double > QwtLinearColorMap::colorStops () const Return all positions of color stops in increasing order

QwtColorTable QwtColorMap::colorTable (const QwtDoubleInterval &interval) const [virtual, inherited] 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 * QwtLinearColorMap::copy () const [virtual]

Clone the color map.

Implements QwtColorMap.

QwtColorMap::Format QwtColorMap::format () const [inline, inherited] Returns

Intended format of the color map

See also:

Format

QwtLinearColorMap::Mode QwtLinearColorMap::mode () const Returns

Mode of the color map

See also:

setMode()

QwtLinearColorMap & QwtLinearColorMap::operator= (const QwtLinearColorMap &other)

Assignment operator.

QRgb QwtLinearColorMap::rgb (const QwtDoubleInterval &interval, doublevalue) const [virtual] Map a value of a given interval into a rgb value

Parameters:

interval Range for all values
value Value to map into a rgb value

Implements QwtColorMap.

void QwtLinearColorMap::setColorInterval (const QColor &color1, const QColor &color2) Set the color range

Add stops at 0.0 and 1.0.

Parameters:

color1 Color used for the minimum value of the value interval
color2 Color used for the maximum value of the value interval

See also:

color1(), color2()

void QwtLinearColorMap::setMode (Modemode)

Set the mode of the color map. FixedColors means the color is calculated from the next lower color stop. ScaledColors means the color is calculated by interpolating the colors of the adjacent stops.

See also:

mode()

Author

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Info

Mon Aug 1 2011 Version 5.2.2 Qwt User's Guide