Base class for scale engines. More...

#include <qwt_scale_engine.h>

Inheritance diagram for QwtScaleEngine:

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

typedef QFlags< Attribute >	Attributes

Public Member Functions
	QwtScaleEngine (uint base=10)

virtual	~QwtScaleEngine ()
	Destructor.

void	setBase (uint base)

uint	base () const

void	setAttribute (Attribute, bool on=true)

bool	testAttribute (Attribute) const

void	setAttributes (Attributes)

Attributes	attributes () const

void	setReference (double)
	Specify a reference point.

double	reference () const

void	setMargins (double lower, double upper)
	Specify margins at the scale's endpoints.

double	lowerMargin () const

double	upperMargin () const

virtual void	autoScale (int maxNumSteps, double &x1, double &x2, double &stepSize) const =0

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

void	setTransformation (QwtTransform *)

QwtTransform *	transformation () const

Protected Member Functions
bool	contains (const QwtInterval &, double value) const

QList< double >	strip (const QList< double > &, const QwtInterval &) const

double	divideInterval (double intervalSize, int numSteps) const

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.

Definition at line 45 of file qwt_scale_engine.h.

Member Typedef Documentation

◆ Attributes

typedef QFlags<Attribute > QwtScaleEngine::Attributes

An ORed combination of Attribute values.

Definition at line 78 of file qwt_scale_engine.h.

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.

Definition at line 54 of file qwt_scale_engine.h.

Constructor & Destructor Documentation

◆ QwtScaleEngine()

QwtScaleEngine::QwtScaleEngine ( uint base = 10 )

explicit

Constructor

Parameters

base	Base of the scale engine

See also: setBase()

Definition at line 222 of file qwt_scale_engine.cpp.

◆ ~QwtScaleEngine()

QwtScaleEngine::~QwtScaleEngine ( )

virtual

Destructor.

Definition at line 230 of file qwt_scale_engine.cpp.

Member Function Documentation

◆ attributes()

QwtScaleEngine::Attributes QwtScaleEngine::attributes ( ) const

Returns: Scale attributes

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

Definition at line 451 of file qwt_scale_engine.cpp.

◆ autoScale()

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

pure virtual

Align and divide an interval

Parameters

maxNumSteps	Max. number of steps
x1	First limit of the interval (In/Out)
x2	Second limit of the interval (In/Out)
stepSize	Step size (Return value)

Implemented in QwtDateScaleEngine, QwtLinearScaleEngine, and QwtLogScaleEngine.

◆ base()

uint QwtScaleEngine::base ( ) const

Returns: base Base of the scale engine

See also: setBase()

Definition at line 500 of file qwt_scale_engine.cpp.

◆ 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

Definition at line 395 of file qwt_scale_engine.cpp.

◆ contains()

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

protected

Check if an interval "contains" a value

Parameters

interval	Interval
value	Value

Returns: True, when the value is inside the interval

Definition at line 341 of file qwt_scale_engine.cpp.

◆ divideInterval()

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

protected

Calculate a step size for an interval size

Parameters

intervalSize	Interval size
numSteps	Number of steps

Returns: Step size

Definition at line 326 of file qwt_scale_engine.cpp.

◆ divideScale()

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

pure virtual

Calculate a scale division.

Parameters

x1	First interval limit
x2	Second interval limit
maxMajorSteps	Maximum for the number of major steps
maxMinorSteps	Maximum number of minor steps
stepSize	Step size. If stepSize == 0.0, the scaleEngine calculates one.

Returns: Calculated scale division

Implemented in QwtDateScaleEngine, QwtLinearScaleEngine, and QwtLogScaleEngine.

◆ lowerMargin()

double QwtScaleEngine::lowerMargin ( ) const

Returns: the margin at the lower end of the scale The default margin is 0.

See also: setMargins()

Definition at line 280 of file qwt_scale_engine.cpp.

◆ reference()

double QwtScaleEngine::reference ( ) const

Returns: the reference value

See also: setReference(), setAttribute()

Definition at line 474 of file qwt_scale_engine.cpp.

◆ setAttribute()

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

Change a scale attribute

Parameters

attribute	Attribute to change
on	On/Off

See also: Attribute, testAttribute()

Definition at line 417 of file qwt_scale_engine.cpp.

◆ setAttributes()

void QwtScaleEngine::setAttributes ( Attributes attributes )

Change the scale attribute

Parameters

attributes Set scale attributes

See also: Attribute, attributes()

Definition at line 442 of file qwt_scale_engine.cpp.

◆ setBase()

void QwtScaleEngine::setBase ( uint base )

Set the base of the scale 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

Parameters

base	Base of the engine

See also: base()

Definition at line 491 of file qwt_scale_engine.cpp.

◆ setMargins()

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

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()

Definition at line 312 of file qwt_scale_engine.cpp.

◆ setReference()

void QwtScaleEngine::setReference ( double reference )

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

Definition at line 465 of file qwt_scale_engine.cpp.

◆ setTransformation()

void QwtScaleEngine::setTransformation ( QwtTransform * transform )

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()

Definition at line 248 of file qwt_scale_engine.cpp.

◆ strip()

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

protected

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

Parameters

ticks	Tick list
interval	Interval

Returns: Stripped tick list

Definition at line 364 of file qwt_scale_engine.cpp.

◆ testAttribute()

bool QwtScaleEngine::testAttribute ( Attribute attribute ) const

Returns: True, if attribute is enabled.

Parameters

attribute Attribute to be tested

See also: Attribute, setAttribute()

Definition at line 431 of file qwt_scale_engine.cpp.

◆ transformation()

QwtTransform * QwtScaleEngine::transformation ( ) const

Create and return a clone of the transformation of the engine. When the engine has no special transformation NULL is returned, indicating no transformation.

Returns: A clone of the transformation

See also: setTransformation()

Definition at line 265 of file qwt_scale_engine.cpp.

◆ upperMargin()

double QwtScaleEngine::upperMargin ( ) const

Returns: the margin at the upper end of the scale The default margin is 0.

See also: setMargins()

Definition at line 291 of file qwt_scale_engine.cpp.

Public Types

Public Member Functions

Protected Member Functions

Detailed Description

Member Typedef Documentation

◆ Attributes

Member Enumeration Documentation

◆ Attribute

Constructor & Destructor Documentation

◆ QwtScaleEngine()

◆ ~QwtScaleEngine()

Member Function Documentation

◆ attributes()

◆ autoScale()

◆ base()

◆ buildInterval()

◆ contains()

◆ divideInterval()

◆ divideScale()

◆ lowerMargin()

◆ reference()

◆ setAttribute()

◆ setAttributes()

◆ setBase()

◆ setMargins()

◆ setReference()

◆ setTransformation()

◆ strip()

◆ testAttribute()

◆ transformation()

◆ upperMargin()