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 }
typedef QFlags< Attribute >	Attributes
	Layout attributes.
Public Member Functions
Attributes	attributes () const
virtual void	autoScale (int maxNumSteps, double &x1, double &x2, double &stepSize) const =0
uint	base () const
virtual QwtScaleDiv	divideScale (double x1, double x2, int maxMajorSteps, int maxMinorSteps, double stepSize=0.0) const =0
	Calculate a scale division.
double	lowerMargin () const
	QwtScaleEngine (uint base=10)
double	reference () const
void	setAttribute (Attribute, bool on=true)
void	setAttributes (Attributes)
void	setBase (uint base)
void	setMargins (double lower, double upper)
	Specify margins at the scale's endpoints.
void	setReference (double reference)
	Specify a reference point.
void	setTransformation (QwtTransform *)
bool	testAttribute (Attribute) const
QwtTransform *	transformation () const
double	upperMargin () const
virtual	~QwtScaleEngine ()
	Destructor.
Protected Member Functions
QwtInterval	buildInterval (double v) const
	Build an interval around a value.
bool	contains (const QwtInterval &, double val) const
double	divideInterval (double interval, int numSteps) const
QList< double >	strip (const QList< double > &, const QwtInterval &) const
Private Attributes
PrivateData *	d_data

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

typedef QFlags<Attribute> QwtScaleEngine::Attributes

Layout attributes.

Definition at line 79 of file qwt_scale_engine.h.

Member Enumeration Documentation

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 ( uint base = 10 ) [explicit]

Constructor

Parameters:

base	Base of the scale engine

See also:: setBase()

Definition at line 227 of file qwt_scale_engine.cpp.

QwtScaleEngine::~QwtScaleEngine ( ) [virtual]

Destructor.

Definition at line 235 of file qwt_scale_engine.cpp.

Member Function Documentation

QwtScaleEngine::Attributes QwtScaleEngine::attributes ( ) const

Returns:: Scale attributes

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

Definition at line 455 of file qwt_scale_engine.cpp.

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 QwtLogScaleEngine, QwtLinearScaleEngine, and QwtDateScaleEngine.

uint QwtScaleEngine::base ( ) const

Returns:: base Base of the scale engine

See also:: setBase()

Definition at line 504 of file qwt_scale_engine.cpp.

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], otherwide it is [0.5 * v, 1.5 * v]

Parameters:

value Initial value

Returns:: Calculated interval

Definition at line 400 of file qwt_scale_engine.cpp.

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 346 of file qwt_scale_engine.cpp.

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 331 of file qwt_scale_engine.cpp.

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 QwtLogScaleEngine, QwtLinearScaleEngine, and QwtDateScaleEngine.

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 285 of file qwt_scale_engine.cpp.

double QwtScaleEngine::reference ( ) const

Returns:: the reference value

See also:: setReference(), setAttribute()

Definition at line 478 of file qwt_scale_engine.cpp.

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 421 of file qwt_scale_engine.cpp.

void QwtScaleEngine::setAttributes ( Attributes attributes )

Change the scale attribute

Parameters:

attributes Set scale attributes

See also:: Attribute, attributes()

Definition at line 446 of file qwt_scale_engine.cpp.

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 495 of file qwt_scale_engine.cpp.

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 317 of file qwt_scale_engine.cpp.

void QwtScaleEngine::setReference ( double r )

Specify a reference point.

Parameters:

r	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 469 of file qwt_scale_engine.cpp.

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 253 of file qwt_scale_engine.cpp.

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 369 of file qwt_scale_engine.cpp.

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 435 of file qwt_scale_engine.cpp.

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 transfomation

See also:: setTransformation()

Definition at line 270 of file qwt_scale_engine.cpp.

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 296 of file qwt_scale_engine.cpp.

Member Data Documentation

PrivateData* QwtScaleEngine::d_data [private]

Reimplemented in QwtDateScaleEngine.

Definition at line 141 of file qwt_scale_engine.h.

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

Classes

Public Types

Public Member Functions

Protected Member Functions

Private Attributes

Detailed Description

Member Typedef Documentation

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation