Base class for scale engines. More...

#include <qwt_scale_engine.h>

Inheritance diagram for QwtScaleEngine:

Classes
class	PrivateData

Public Types
enum	Attribute { NoAttribute = 0x00 , IncludeReference = 0x01 , Symmetric = 0x02 , Floating = 0x04 , Inverted = 0x08 }
	Layout attributes. More...

Public Member Functions
	QwtScaleEngine (uint base=10)
	Constructor.

void	setBase (uint base)
	Set the base.

uint	base () const
	Return base of the scale engine.

void	setAttribute (Attribute, bool on=true)
	Set an attribute.

bool	testAttribute (Attribute) const
	Test if an attribute is enabled.

void	setAttributes (Attributes)
	Set attributes.

Attributes	attributes () const
	Return scale attributes.

void	setReference (double)
	Set the reference value.

double	reference () const
	Return the reference value.

void	setMargins (double lower, double upper)
	Set the margins.

double	lowerMargin () const
	Return the margin at the lower end of the scale.

double	upperMargin () const
	Return the margin at the upper end of the scale.

virtual void	autoScale (int maxNumSteps, double &x1, double &x2, double &stepSize) const =0
	Align and divide an interval.

virtual QwtScaleDiv	divideScale (double x1, double x2, int maxMajorSteps, int maxMinorSteps, double stepSize=0.0) const =0
	Calculate a scale division.

void	setTransformation (QwtTransform *)
	Set the transformation.

QwtTransform *	transformation () const
	Create and return a clone of the transformation of the engine.

Protected Member Functions
bool	contains (const QwtInterval &, double value) const
	Check if an interval contains a value.

QList< double >	strip (const QList< double > &, const QwtInterval &) const
	Strip values outside an interval.

double	divideInterval (double intervalSize, int numSteps) const
	Divide an interval.

QwtInterval	buildInterval (double value) const
	Build an interval around a value.

Detailed Description

Base class for scale engines.

A scale engine tries to find "reasonable" ranges and step sizes for scales. The layout of the scale can be varied with setAttribute(). Qwt offers implementations for logarithmic and linear scales.

See also: QwtLinearScaleEngine, QwtLogScaleEngine

Member Enumeration Documentation

◆ Attribute

enum QwtScaleEngine::Attribute

Layout attributes.

See also: setAttribute(), testAttribute(), reference(), lowerMargin(), upperMargin()

Enumerator
NoAttribute	No attributes.
IncludeReference	Build a scale which includes the reference() value.
Symmetric	Build a scale which is symmetric to the reference() value.
Floating	The endpoints of the scale are supposed to be equal the outmost included values plus the specified margins (see setMargins()). If this attribute is not set, the endpoints of the scale will be integer multiples of the step size.
Inverted	Turn the scale upside down.

Constructor & Destructor Documentation

◆ QwtScaleEngine()

QwtScaleEngine::QwtScaleEngine ( uint base = 10 )

explicit

Constructor.

Parameters

base	Base of the scale engine

See also: setBase()

Member Function Documentation

◆ attributes()

QwtScaleEngine::Attributes QwtScaleEngine::attributes ( ) const

Return scale attributes.

Returns: the attributes; Scale attributes

See also: Attribute, setAttributes(), testAttribute()

◆ autoScale()

virtual void QwtScaleEngine::autoScale	(	int	maxNumSteps,
		double &	x1,
		double &	x2,
		double &	stepSize
	)		const

pure virtual

Align and divide an interval.

Implemented in QwtLinearScaleEngine, QwtLogScaleEngine, and QwtDateScaleEngine.

◆ base()

uint QwtScaleEngine::base ( ) const

Return base of the scale engine.

Returns: the base; Base of the scale engine

See also: setBase()

◆ buildInterval()

QwtInterval QwtScaleEngine::buildInterval ( double value ) const

protected

Build an interval around a value.

In case of v == 0.0 the interval is [-0.5, 0.5], otherwise it is [0.5 * v, 1.5 * v]

Parameters

value Initial value

Returns: Calculated interval

◆ contains()

bool QwtScaleEngine::contains	(	const QwtInterval &	interval,
		double	value
	)		const

protected

Check if an interval contains a value.

Check if an interval "contains" a value.

Parameters

interval	Interval
value	Value

Returns: True, when the value is inside the interval

◆ divideInterval()

double QwtScaleEngine::divideInterval	(	double	intervalSize,
		int	numSteps
	)		const

protected

Divide an interval.

Calculate a step size for an interval size.

Parameters

intervalSize	Interval size
numSteps	Number of steps

Returns: Step size

◆ divideScale()

virtual QwtScaleDiv QwtScaleEngine::divideScale	(	double	x1,
		double	x2,
		int	maxMajorSteps,
		int	maxMinorSteps,
		double	stepSize = `0.0`
	)		const

pure virtual

Calculate a scale division.

Implemented in QwtLinearScaleEngine, QwtLogScaleEngine, and QwtDateScaleEngine.

◆ lowerMargin()

double QwtScaleEngine::lowerMargin ( ) const

Return the margin at the lower end of the scale.

Returns: the lower margin; The margin at the lower end

The default margin is 0.

See also: setMargins()

◆ reference()

double QwtScaleEngine::reference ( ) const

Return the reference value.

Returns: the reference value; The reference value

See also: setReference(), setAttribute()

◆ setAttribute()

void QwtScaleEngine::setAttribute	(	Attribute	attribute,
		bool	on = `true`
	)

Set an attribute.

Change a scale attribute.

Parameters

attribute	Attribute to change
on	On/Off

See also: Attribute, testAttribute()

◆ setAttributes()

void QwtScaleEngine::setAttributes ( Attributes attributes )

Set attributes.

Change the scale attribute.

Parameters

attributes Set scale attributes

See also: Attribute, attributes()

◆ setBase()

void QwtScaleEngine::setBase ( uint base )

Set the base.

Set the base of the scale engine.

Parameters

base	Base of the engine

While a base of 10 is what 99.9% of all applications need, certain scales might need a different base: f.e 2. The default setting is 10.

See also: base()

◆ setMargins()

void QwtScaleEngine::setMargins	(	double	lower,
		double	upper
	)

Set the margins.

Specify margins at the scale's endpoints.

Parameters

lower	Minimum distance between the scale's lower boundary and the smallest enclosed value
upper	Minimum distance between the scale's upper boundary and the greatest enclosed value

Margins can be used to leave a minimum amount of space between the enclosed intervals and the boundaries of the scale.

Warning: QwtLogScaleEngine measures the margins in decades.

See also: upperMargin(), lowerMargin()

◆ setReference()

void QwtScaleEngine::setReference ( double reference )

Set the reference value.

Specify a reference point.

Parameters

reference New reference value

The reference point is needed if options IncludeReference or Symmetric are active. Its default value is 0.0.

See also: Attribute

◆ setTransformation()

void QwtScaleEngine::setTransformation ( QwtTransform * transform )

Set the transformation.

Assign a transformation.

Parameters

transform Transformation

The transformation object is used as factory for clones that are returned by transformation(). The scale engine takes ownership of the transformation.

See also: QwtTransform::copy(), transformation()

◆ strip()

QList< double > QwtScaleEngine::strip	(	const QList< double > &	ticks,
		const QwtInterval &	interval
	)		const

protected

Strip values outside an interval.

Remove ticks from a list, that are not inside an interval.

Parameters

ticks	Tick list
interval	Interval

Returns: Stripped tick list

◆ testAttribute()

bool QwtScaleEngine::testAttribute ( Attribute attribute ) const

Test if an attribute is enabled.

Returns: true if an attribute is set

Parameters

attribute Attribute to be tested

Returns: True, if attribute is enabled

See also: Attribute, setAttribute()

◆ transformation()

QwtTransform * QwtScaleEngine::transformation ( ) const

Create and return a clone of the transformation of the engine.

Returns: the transformation

When the engine has no special transformation nullptr is returned, indicating no transformation.

Returns: A clone of the transformation

See also: setTransformation()

◆ upperMargin()

double QwtScaleEngine::upperMargin ( ) const

Return the margin at the upper end of the scale.

Returns: the upper margin; The margin at the upper end

The default margin is 0.

See also: setMargins()

The documentation for this class was generated from the following files:

/home/runner/work/QWT/QWT/src/core/qwt_scale_engine.h
/home/runner/work/QWT/QWT/src/core/qwt_scale_engine.cpp

Classes

Public Types

Public Member Functions

Protected Member Functions

Detailed Description

Member Enumeration Documentation

◆ Attribute

Constructor & Destructor Documentation

◆ QwtScaleEngine()

Member Function Documentation

◆ attributes()

◆ autoScale()

◆ base()

◆ buildInterval()

◆ contains()

◆ divideInterval()

◆ divideScale()

◆ lowerMargin()

◆ reference()

◆ setAttribute()

◆ setAttributes()

◆ setBase()

◆ setMargins()

◆ setReference()

◆ setTransformation()

◆ strip()

◆ testAttribute()

◆ transformation()

◆ upperMargin()