#include <qwt_scale_engine.h>

Inherited by QwtLinearScaleEngine, and QwtLog10ScaleEngine.

Public Types
enum	Attribute { NoAttribute = 0x00, IncludeReference = 0x01, Symmetric = 0x02, Floating = 0x04, Inverted = 0x08 }
typedef QFlags< Attribute >	Attributes
Public Member Functions
Attributes	attributes () const
virtual void	autoScale (int maxNumSteps, double &x1, double &x2, double &stepSize) const =0
virtual QwtScaleDiv	divideScale (double x1, double x2, int maxMajSteps, int maxMinSteps, double stepSize=0.0) const =0
double	lowerMargin () const
	QwtScaleEngine ()
double	reference () const
void	setAttribute (Attribute, bool on=true)
void	setAttributes (Attributes)
void	setMargins (double lower, double upper)
void	setReference (double reference)
bool	testAttribute (Attribute) const
virtual QwtScaleTransformation *	transformation () const =0
double	upperMargin () const
virtual	~QwtScaleEngine ()
Protected Member Functions
QwtInterval	buildInterval (double v) const
bool	contains (const QwtInterval &, double val) const
double	divideInterval (double interval, int numSteps) const
QList< double >	strip (const QList< double > &, const QwtInterval &) const

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 (log10) and linear scales. Contributions for other types of scale engines (date/time, log2 ... ) are welcome.

Member Typedef Documentation

typedef QFlags<Attribute> QwtScaleEngine::Attributes

Layout attributes.

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.

Constructor & Destructor Documentation

QwtScaleEngine::QwtScaleEngine ( ) [explicit]

Constructor.

QwtScaleEngine::~QwtScaleEngine ( ) [virtual]

Destructor.

Member Function Documentation

QwtScaleEngine::Attributes QwtScaleEngine::attributes ( ) const

Return the scale attributes

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

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 QwtLog10ScaleEngine, and QwtLinearScaleEngine.

QwtInterval QwtScaleEngine::buildInterval ( double v ) const [protected]

Build an interval for a value.

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

bool QwtScaleEngine::contains	(	const QwtInterval &	interval,
		double	value
	)		const `[protected]`

Check if an interval "contains" a value

Parameters:

interval	Interval
value	Value

See also:: QwtScaleArithmetic::compareEps()

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

virtual QwtScaleDiv QwtScaleEngine::divideScale	(	double	x1,
		double	x2,
		int	maxMajSteps,
		int	maxMinSteps,
		double	stepSize = `0.0`
	)		const `[pure virtual]`

Calculate a scale division.

Parameters:

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

Implemented in QwtLog10ScaleEngine, and QwtLinearScaleEngine.

double QwtScaleEngine::lowerMargin ( ) const

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

See also:: setMargins()

double QwtScaleEngine::reference ( ) const

Returns:: the reference value

See also:: setReference(), 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()

void QwtScaleEngine::setAttributes ( Attributes attributes )

Change the scale attribute

Parameters:

attributes Set scale attributes

See also:: Attribute, attributes()

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:

QwtLog10ScaleEngine measures the margins in decades.

See also:: upperMargin(), lowerMargin()

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

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

bool QwtScaleEngine::testAttribute ( Attribute attribute ) const

Check if a attribute is set.

Parameters:

attribute Attribute to be tested

See also:: Attribute, setAttribute()

virtual QwtScaleTransformation* QwtScaleEngine::transformation ( ) const [pure virtual]

Returns:: a transformation

Implemented in QwtLog10ScaleEngine, and QwtLinearScaleEngine.

double QwtScaleEngine::upperMargin ( ) const

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

See also:: setMargins()

Public Types

Public Member Functions

Protected Member Functions

Detailed Description

Member Typedef Documentation

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation