---
name: "QwtScaleIf"
section: "3"
platform: "linux"
package: "libqwt-doc"
version: "4.2.0-6"
release: "Debian 6.0 (Squeeze)"
platforms: ["linux"]
url: "https://new.carta.tech/QwtScaleIf"
---

# QwtScaleIf(3)

## NAME

QwtScaleIf -

## SYNOPSIS

Inherited by **QwtKnob**, **QwtSlider**, and **QwtThermo**.

## Detailed Description

An interface class for widgets containing a scale.

This interface class is used to provide classes a **QwtScaleDraw** and an interface to access that scale.

Definition at line 40 of file qwt\_sclif.h.

### Public Member Functions

**QwtScaleIf** ()\
 virtual **~QwtScaleIf** ()\
 void **setScale** (double vmin, double vmax, int logarithmic=0)\
 void **setScale** (double vmin, double vmax, double step, int logarithmic=0)\
 void **setScale** (const **QwtScaleDiv** &s)\
 void **setScaleMaxMajor** (int ticks)\
 void **setScaleMaxMinor** (int ticks)\
 void **autoScale** ()\
 int **scaleMaxMinor** () const\
 int **scaleMaxMajor** () const\
 void **setScaleDraw** (**QwtScaleDraw** \*)\
 const **QwtScaleDraw** \* **scaleDraw** () const\

### Protected Member Functions

bool **hasUserScale** ()\
 virtual void **scaleChange** ()=0\
 **QwtScaleDraw** \* **scaleDraw** ()\

## Constructor & Destructor Documentation

### QwtScaleIf::QwtScaleIf ()

Constructor.

Definition at line 13 of file qwt\_sclif.cpp.

References QwtScaleDraw::setScale().

### QwtScaleIf::~QwtScaleIf ()` [virtual]`

Destructor.

Definition at line 24 of file qwt\_sclif.cpp.

## Member Function Documentation

### void QwtScaleIf::autoScale ()

Advise the widget to control the scale range internally.

Autoscaling is on by default.

**See also:**

**QwtScaleIf::setScale()**

Definition at line 99 of file qwt\_sclif.cpp.

References scaleChange().

### bool QwtScaleIf::hasUserScale ()` [protected]`

Check for user-defined scale.

Definition at line 62 of file qwt\_sclif.h.

Referenced by QwtSlider::rangeChange(), QwtSlider::scaleChange(), and QwtThermo::setRange().

### virtual void QwtScaleIf::scaleChange ()` [protected, pure virtual]`

Notify changed scale.

Implemented in **QwtSlider**, and **QwtThermo**.

Referenced by autoScale(), setScale(), setScaleMaxMajor(), and setScaleMaxMinor().

### QwtScaleDraw \* QwtScaleIf::scaleDraw ()` [protected]`

**Returns:**

scale draw

**See also:**

**QwtScaleIf::setScaleDraw**

Definition at line 168 of file qwt\_sclif.cpp.

### const QwtScaleDraw \* QwtScaleIf::scaleDraw () const

**Returns:**

scale draw

**See also:**

**QwtScaleIf::setScaleDraw**

Definition at line 177 of file qwt\_sclif.cpp.

Referenced by QwtThermo::draw(), QwtSlider::draw(), QwtKnob::draw(), QwtSlider::getScrollMode(), QwtSlider::getValue(), QwtSlider::layoutSlider(), QwtThermo::layoutThermo(), QwtThermo::minimumSizeHint(), QwtSlider::minimumSizeHint(), QwtKnob::minimumSizeHint(), QwtKnob::QwtKnob(), QwtSlider::QwtSlider(), QwtSlider::rangeChange(), QwtSlider::scaleChange(), QwtThermo::setRange(), QwtKnob::setTotalAngle(), QwtThermo::sizePolicy(), and QwtSlider::xyPosition().

### int QwtScaleIf::scaleMaxMajor () const

**Returns:**

max. number of major tick intervals

Definition at line 55 of file qwt\_sclif.h.

Referenced by QwtSlider::rangeChange(), QwtSlider::scaleChange(), and QwtThermo::setRange().

### int QwtScaleIf::scaleMaxMinor () const

**Returns:**

max. number of minor tick intervals

Definition at line 53 of file qwt\_sclif.h.

Referenced by QwtSlider::rangeChange(), QwtSlider::scaleChange(), and QwtThermo::setRange().

### void QwtScaleIf::setScale (const QwtScaleDiv & s)

Assign a user-defined scale division

**Parameters:**

*s* scale division

Definition at line 81 of file qwt\_sclif.cpp.

References QwtScaleDiv::majCnt(), QwtScaleDiv::minCnt(), scaleChange(), QwtScaleDraw::scaleDiv(), and QwtScaleDraw::setScale().

### void QwtScaleIf::setScale (double vmin, double vmax, double step, int logarithmic = `0`)

Specify a user-defined scale.

By default, the widget is supposed to control the range of its scale automatically, but sometimes it is desirable to have a user-defined scale which is not in sync with the widget's range, e.g. if a logarithmic scale is needed (sliders don't support that) or if the scale is required to have a fixed range (say 0...100%), independent of the widget's range.

**Parameters:**

*vmin* \
 *vmax* interval boundaries \
 *step* major step size \
 *logarithmic* If != 0, build a logarithmic scale

**See also:**

**QwtScaleIf::autoScale()**

Definition at line 66 of file qwt\_sclif.cpp.

References scaleChange(), QwtScaleDraw::scaleDiv(), and QwtScaleDraw::setScale().

### void QwtScaleIf::setScale (double vmin, double vmax, int logarithmic = `0`)

Specify a user-defined scale.

By default, the widget is supposed to control the range of its scale automatically, but sometimes it is desirable to have a user-defined scale which is not in sync with the widget's range, e.g. if a logarithmic scale is needed (sliders don't support that) or if the scale is required to have a fixed range (say 0...100%), independent of the widget's range.

**Parameters:**

*vmin* \
 *vmax* boundary values \
 *logarithmic* If != 0, Build a logarithmic scale

**See also:**

**QwtScaleIf::autoScale()**

Definition at line 44 of file qwt\_sclif.cpp.

### void QwtScaleIf::setScaleDraw (QwtScaleDraw \* sd)

Set a scale draw sd has to be created with new and will be deleted in **QwtScaleIf::~QwtScaleIf** or the next call of **QwtScaleIf::setScaleDraw**.

Definition at line 155 of file qwt\_sclif.cpp.

### void QwtScaleIf::setScaleMaxMajor (int ticks)

Set the maximum number of major tick intervals.

The scale's major ticks are calculated automatically such that the number of major intervals does not exceed ticks. The default value is 5.

**Parameters:**

*ticks* maximal number of major ticks.

**See also:**

**QwtScaleDraw**

Definition at line 117 of file qwt\_sclif.cpp.

References QwtScaleDiv::hBound(), QwtScaleDiv::lBound(), QwtScaleDiv::logScale(), scaleChange(), QwtScaleDraw::scaleDiv(), and QwtScaleDraw::setScale().

### void QwtScaleIf::setScaleMaxMinor (int ticks)

Set the maximum number of minor tick intervals.

The scale's minor ticks are calculated automatically such that the number of minor intervals does not exceed ticks. The default value is 3.

**Parameters:**

*ticks*

**See also:**

**QwtScaleDraw**

Definition at line 138 of file qwt\_sclif.cpp.

References QwtScaleDiv::hBound(), QwtScaleDiv::lBound(), QwtScaleDiv::logScale(), scaleChange(), QwtScaleDraw::scaleDiv(), and QwtScaleDraw::setScale().

## Author

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