QwtScaleEngine Class Reference

Inheritance diagram for QwtScaleEngine:

[legend]List of all members.

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Detailed Description

Base class for scale engines.

A scale engine trys to find "reasonable" ranges and step sizes for scales.

The layout of the scale can be varied with setOptions().

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

Definition at line 50 of file qwt_scale_engine.h.

Public Types
enum	Attribute {   NoAttribute = 0,   IncludeReference = 1,   Symmetric = 2,   Floating = 4,   Inverted = 8 }
Public Member Functions
	QwtScaleEngine ()
virtual	~QwtScaleEngine ()
void	setAttribute (Attribute, bool on=true)
bool	testAttribute (Attribute) const
void	setAttributes (int)
int	attributes () const
void	setReference (double reference)
double	reference () const
void	setMargins (double m1, double m2)
double	loMargin () const
double	hiMargin () 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
virtual QwtScaleTransformation *	transformation () const =0
Protected Member Functions
bool	contains (const QwtDoubleInterval &, double val) const
QwtValueList	strip (const QwtValueList &, const QwtDoubleInterval &) const
double	divideInterval (double interval, int numSteps) const
QwtDoubleInterval	buildInterval (double v) const

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Member Enumeration Documentation

enum QwtScaleEngine::Attribute

see QwtScaleEngine::setOption, testOption Definition at line 54 of file qwt_scale_engine.h.

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Constructor & Destructor Documentation

QwtScaleEngine::QwtScaleEngine (   )  [explicit]

Ctor. Definition at line 169 of file qwt_scale_engine.cpp.

QwtScaleEngine::~QwtScaleEngine (   )  [virtual]

Dtor. Definition at line 176 of file qwt_scale_engine.cpp.

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Member Function Documentation

int QwtScaleEngine::attributes (   )  const

Return the scale attributes Definition at line 379 of file qwt_scale_engine.cpp. Referenced by QwtLog10ScaleEngine::divideScale().

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 QwtLinearScaleEngine, and QwtLog10ScaleEngine.

QwtDoubleInterval 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] Definition at line 309 of file qwt_scale_engine.cpp. Referenced by QwtLog10ScaleEngine::autoScale(), and QwtLinearScaleEngine::autoScale().

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

Check if an interval "contains" a value Parameters: interval  Interval value  Value See also: QwtScaleArithmetic::compareEps Definition at line 251 of file qwt_scale_engine.cpp. References QwtScaleArithmetic::compareEps(), QwtDoubleInterval::isValid(), QwtDoubleInterval::maxValue(), QwtDoubleInterval::minValue(), and QwtDoubleInterval::width(). Referenced by strip().

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 233 of file qwt_scale_engine.cpp. References QwtScaleArithmetic::ceil125(), and QwtScaleArithmetic::divideEps(). Referenced by QwtLog10ScaleEngine::autoScale(), QwtLinearScaleEngine::autoScale(), QwtLog10ScaleEngine::divideScale(), and QwtLinearScaleEngine::divideScale().

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 QwtLinearScaleEngine, and QwtLog10ScaleEngine.

double QwtScaleEngine::hiMargin (   )  const

Returns: the margin at the upper end of the scale The default margin is 0. See also: QwtScaleEngine::setMargins() Definition at line 198 of file qwt_scale_engine.cpp. Referenced by QwtLog10ScaleEngine::autoScale(), QwtLinearScaleEngine::autoScale(), and QwtLog10ScaleEngine::divideScale().

double QwtScaleEngine::loMargin (   )  const

Returns: the margin at the lower end of the scale The default margin is 0. See also: QwtScaleEngine::setMargins() Definition at line 187 of file qwt_scale_engine.cpp. Referenced by QwtLog10ScaleEngine::autoScale(), QwtLinearScaleEngine::autoScale(), and QwtLog10ScaleEngine::divideScale().

double QwtScaleEngine::reference (   )  const

Returns: the reference value See also: QwtScaleEngine::setReference(), QwtScaleEngine::setOptions() Definition at line 400 of file qwt_scale_engine.cpp. Referenced by QwtLog10ScaleEngine::autoScale(), QwtLinearScaleEngine::autoScale(), and QwtLog10ScaleEngine::divideScale().

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

Change a scale attribute Parameters: attribute  Attribute to change on  On/Off The behaviour of the scale engine can be changed with the following attributes: QwtAutoscale::IncludeReference Build a scale which includes the reference value. QwtScaleEngine::Symmetric Build a scale which is symmetric to the reference value. QwtScaleEngine::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. QwtScaleEngine::Inverted Turn the scale upside down. See also: QwtScaleEngine::testAttribute() Definition at line 346 of file qwt_scale_engine.cpp.

void QwtScaleEngine::setAttributes (  int  attributes  )

Change the scale attribute Parameters: attributes  Set scale attributes See also: QwtScaleEngine::attributes() Definition at line 371 of file qwt_scale_engine.cpp. Referenced by QwtLog10ScaleEngine::divideScale().

void QwtScaleEngine::setMargins (  double  mlo, double  mhi )

Specify margins at the scale's endpoints. Parameters: mlo  minimum distance between the scale's lower boundary and the smallest enclosed value mhi  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: QwtScaleEngine::hiMargin, QwtScaleEngine::loMargin Definition at line 219 of file qwt_scale_engine.cpp. Referenced by QwtLog10ScaleEngine::divideScale().

void QwtScaleEngine::setReference (  double  r  )

Specify a reference point. Parameters: r  new reference value The reference point is needed if options IncludeRef or Symmetric are active. Its default value is 0.0. Definition at line 391 of file qwt_scale_engine.cpp. Referenced by QwtLog10ScaleEngine::divideScale().

QwtValueList QwtScaleEngine::strip (  const QwtValueList &  ticks, const QwtDoubleInterval &  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 280 of file qwt_scale_engine.cpp. References contains(), and QwtDoubleInterval::isValid().

bool QwtScaleEngine::testAttribute (  Attribute  attribute  )  const

Check if a attribute is set. Parameters: attribute  Attribute to be tested See also: QwtScaleEngine::setAttribute() for a description of the possible options. Definition at line 360 of file qwt_scale_engine.cpp. Referenced by QwtLog10ScaleEngine::autoScale(), and QwtLinearScaleEngine::autoScale().

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

Returns: a transformation Implemented in QwtLinearScaleEngine, and QwtLog10ScaleEngine.

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