# QwtLinearColorMap Class Reference

QwtLinearColorMap builds a color map from color stops. More...

`#include <qwt_color_map.h>`

Inheritance diagram for QwtLinearColorMap:

[legend]

List of all members.

## Public Types
enum | Mode { FixedColors, ScaledColors }
## Public Member Functions
| QwtLinearColorMap (QwtColorMap::Format=QwtColorMap::RGB)
| QwtLinearColorMap (const QColor &from, const QColor &to, QwtColorMap::Format=QwtColorMap::RGB)
| QwtLinearColorMap (const QwtLinearColorMap &)
virtual | ~QwtLinearColorMap ()
QwtLinearColorMap & | operator= (const QwtLinearColorMap &)
virtual QwtColorMap * | copy () const
void | setMode (Mode)
Mode | mode () const
void | setColorInterval (const QColor &color1, const QColor &color2)
void | addColorStop (double value, const QColor &)
QwtArray< double > | colorStops () const
QColor | color1 () const
QColor | color2 () const
virtual QRgb | rgb (const QwtDoubleInterval &, double value) const
virtual unsigned char | colorIndex (const QwtDoubleInterval &, double value) const

## 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 QwtLinearColorMap::Mode

Mode of color map

See also:
  setMode(), mode()

## Constructor & Destructor Documentation

QwtLinearColorMap::QwtLinearColorMap | ( | QwtColorMap::Format | format = `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::Format | format = `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 | ( | double | value,
|  | 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 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,
|  | double | value |
| ) |  |  | 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

QwtColorMap * QwtLinearColorMap::copy | ( |  | ) | const`[virtual]`

Clone the color map.

Implements QwtColorMap.

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,
|  | double | value |
| ) |  |  | 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 | ( | Mode | mode | ) |

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()