---
name: "QwtCompassScaleDraw"
section: "3"
platform: "linux"
package: "libqwt-doc"
version: "6.1.4-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/QwtCompassScaleDraw"
---

# QwtCompassScaleDraw(3)

A special scale draw made for QwtCompass.

## NAME

QwtCompassScaleDraw - A special scale draw made for **QwtCompass**.

## SYNOPSIS

`#include <qwt_compass.h>`

Inherits **QwtRoundScaleDraw**.

### Public Member Functions

**QwtCompassScaleDraw** ()\
 Constructor.  **QwtCompassScaleDraw** (const QMap\< double, QString \> &map)\
 Constructor.  void **setLabelMap** (const QMap\< double, QString \> &map)\
 Set a map, mapping values to labels.  QMap\< double, QString \> **labelMap** () const\
 virtual **QwtText** **label** (double value) const\

### Additional Inherited Members

## Detailed Description

A special scale draw made for **QwtCompass**.

**QwtCompassScaleDraw** maps values to strings using a special map, that can be modified by the application

The default map consists of the labels N, NE, E, SE, S, SW, W, NW.

**See also:**

**QwtCompass**

## Constructor & Destructor Documentation

### QwtCompassScaleDraw::QwtCompassScaleDraw ()` [explicit]`

Constructor. Initializes a label map for multiples of 45 degrees

### QwtCompassScaleDraw::QwtCompassScaleDraw (const QMap\< double, QString \> & map)` [explicit]`

Constructor.

**Parameters:**

*map* Value to label map

## Member Function Documentation

### QwtText QwtCompassScaleDraw::label (double value) const` [virtual]`

Map a value to a corresponding label

**Parameters:**

*value* Value that will be mapped

**label()** looks in the **labelMap()** for a corresponding label for value or returns an null text.

**Returns:**

Label

**See also:**

**labelMap()**, **setLabelMap()**

Reimplemented from **QwtAbstractScaleDraw**.

### QMap\< double, QString \> QwtCompassScaleDraw::labelMap () const

**Returns:**

map, mapping values to labels

**See also:**

**setLabelMap()**

### void QwtCompassScaleDraw::setLabelMap (const QMap\< double, QString \> & map)

Set a map, mapping values to labels.

**Parameters:**

*map* Value to label map

The values of the major ticks are found by looking into this map. The default map consists of the labels N, NE, E, SE, S, SW, W, NW.

**Warning:**

The map will have no effect for values that are no major tick values. Major ticks can be changed by QwtScaleDraw::setScale

**See also:**

**labelMap()**, scaleDraw(), setScale()

## Author

Generated automatically by Doxygen for Qwt User's Guide from the source code.