QwtLinearScaleEngine Class Reference

A scale engine for linear scales. More...

#include <qwt_scale_engine.h>

Inheritance diagram for QwtLinearScaleEngine:

List of all members.

Public Types
enum	Attribute {   NoAttribute = 0,   IncludeReference = 1,   Symmetric = 2,   Floating = 4,   Inverted = 8 }
Public Member Functions
int	attributes () const
virtual void	autoScale (int maxSteps, double &x1, double &x2, double &stepSize) const
virtual QwtScaleDiv	divideScale (double x1, double x2, int numMajorSteps, int numMinorSteps, double stepSize=0.0) const
double	lowerMargin () const
double	reference () const
void	setAttribute (Attribute, bool on=true)
void	setAttributes (int)
void	setMargins (double lower, double upper)
void	setReference (double reference)
bool	testAttribute (Attribute) const
virtual QwtScaleTransformation *	transformation () const
double	upperMargin () const
Protected Member Functions
QwtDoubleInterval	align (const QwtDoubleInterval &, double stepSize) const
QwtDoubleInterval	buildInterval (double v) const
bool	contains (const QwtDoubleInterval &, double val) const
double	divideInterval (double interval, int numSteps) const
QwtValueList	strip (const QwtValueList &, const QwtDoubleInterval &) const

---

Detailed Description

A scale engine for linear scales.

The step size will fit into the pattern , where n is an integer.

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Member Enumeration Documentation

enum QwtScaleEngine::Attribute [inherited]

• 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.

See also:

setAttribute(), testAttribute(), reference(), lowerMargin(), upperMargin()

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Member Function Documentation

QwtDoubleInterval QwtLinearScaleEngine::align	(	const QwtDoubleInterval &	interval,
		double	stepSize
	)		const [protected]

Align an interval to a step size.

The limits of an interval are aligned that both are integer multiples of the step size.

Parameters:

interval	Interval
stepSize	Step size

Returns:

Aligned interval

int QwtScaleEngine::attributes

(

)

const [inherited]

Return the scale attributes

See also:

Attribute, setAttributes(), testAttribute()

void QwtLinearScaleEngine::autoScale	(	int	maxNumSteps,
		double &	x1,
		double &	x2,
		double &	stepSize
	)		const [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 (Out)

See also:

setAttribute()

Implements QwtScaleEngine.

QwtDoubleInterval QwtScaleEngine::buildInterval

(

double

v

)

const [protected, inherited]

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 QwtDoubleInterval &	interval,
		double	value
	)		const [protected, inherited]

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, inherited]

Calculate a step size for an interval size

Parameters:

intervalSize	Interval size
numSteps	Number of steps

Returns:

Step size

QwtScaleDiv QwtLinearScaleEngine::divideScale	(	double	x1,
		double	x2,
		int	maxMajSteps,
		int	maxMinSteps,
		double	stepSize = 0.0
	)		const [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, the scaleEngine calculates one.

See also:

QwtScaleEngine::stepSize(), QwtScaleEngine::subDivide()

Implements QwtScaleEngine.

double QwtScaleEngine::lowerMargin

(

)

const [inherited]

Returns:

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

See also:

setMargins()

double QwtScaleEngine::reference

(

)

const [inherited]

Returns:

the reference value

See also:

setReference(), setAttribute()

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

Change a scale attribute

Parameters:

attribute	Attribute to change
on	On/Off

See also:

Attribute, testAttribute()

void QwtScaleEngine::setAttributes

(

int

attributes

)

[inherited]

Change the scale attribute

Parameters:

attributes

Set scale attributes

See also:

Attribute, attributes()

void QwtScaleEngine::setMargins	(	double	lower,
		double	upper
	)		[inherited]

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

)

[inherited]

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

QwtValueList QwtScaleEngine::strip	(	const QwtValueList &	ticks,
		const QwtDoubleInterval &	interval
	)		const [protected, inherited]

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 [inherited]

Check if a attribute is set.

Parameters:

attribute

Attribute to be tested

See also:

Attribute, setAttribute()

QwtScaleTransformation * QwtLinearScaleEngine::transformation

(

)

const [virtual]

Return a transformation, for linear scales

Implements QwtScaleEngine.

double QwtScaleEngine::upperMargin

(

)

const [inherited]

Returns:

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

See also:

setMargins()